7722-84-1

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• Kinetics and mechanism of O-O bond cleavage in the reaction of [Ru III(edta)(H2O)]- with hydroperoxides in aqueous solution
• The reactions of [RuIII(edta)(H2O)]- (1) (edta = ethylenediaminetetraacetate) with tert-butylhydroperoxide ( tBuOOH) and potassium hydrogenpersulfate (KHSO5) were studied kinetically as a function of oxidant concentration and temperature (10-30 °C) at a fixed pH of 6.1 using stopped-flow techniques. Kinetic results were analyzed by using global kinetic analysis techniques. The reaction was found to consist of two steps involving the rapid formation of a [Ru III(edta)(OOR)]2- intermediate, which subsequently undergoes heterolytic cleavage to form [(edta)RuV=O]-. Since [(edta)RuV=O]- was produced almost quantitatively in the reaction of 1 with the hydroperoxides tBuOOH and KHSO 5, the common mechanism is one of heterolytic scission of the O-O bond. The water soluble and easy to oxidize substrate 2,2′-azobis(3- ethylbenzithiazoline-6-sulfonate (ABTS), was employed to substantiate the mechanistic proposal. Reactions were carried out under pseudo-first order conditions for [ABTS] [hydroperoxide] ? [1], and were monitored as a function of time for the formation of the one-electron oxidation product ABTS+. The detailed suggested mechanism is consistent with the reported rate and activation parameters, and discussed in reference to the results reported for the reaction of [RuII(edta)(H 2O)]- with H2O2.
• Chatterjee, Debabrata,Sikdar, Anindita,Patnam, Vidya R.,Theodoridis, Alexander,Van Eldik, Rudi

• p. 3851 - 3856

  (2008)
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• Synergistic Cocatalytic Effect of Carbon Nanodots and Co3O4 Nanoclusters for the Photoelectrochemical Water Oxidation on Hematite
• Cocatalysis plays an important role in enhancing the activity of semiconductor photocatalysts for solar water splitting. Compared to a single cocatalyst configuration, a cocatalytic system consisting of multiple components with different functions may realize outstanding enhancement through their interactions, yet limited research has been reported. Herein we describe the synergistic cocatalytic effect between carbon nanodots (CDots) and Co3O4, which promotes the photoelectrochemical water oxidation activity of the Fe2O3 photoanode with a 60 mV cathodically shifted onset potential. The C/Co3O4-Fe2O3 photoanode exhibits a photocurrent density of 1.48 mA cm-2 at 1.23 V (vs. reversible hydrogen electrode), 78 % higher than that of the bare Fe2O3 photoanode. The slow reaction process on the single CoIII-OH site of the Co3O4 cocatalyst, oxidizing H2O to H2O2 with two photogenerated holes, could be accelerated by the timely H2O2 oxidation to O2 catalyzed on CDots.
• Zhang, Peng,Wang, Tuo,Chang, Xiaoxia,Zhang, Lei,Gong, Jinlong

• p. 5851 - 5855

  (2016)
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• Evidence for urate hydroperoxide as an intermediate in the urate oxidase reaction [14]
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• Sarma,Tipton

• p. 11252 - 11253

  (2000)
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• Oxygen reduction reaction on carbon-supported CoSe2 nanoparticles in an acidic medium
• We investigated the effect of CoSe2/C nanoparticle loading rate on oxygen reduction reaction (ORR) activity and H2O2 production using the rotating disk electrode and the rotating ring-disk electrode techniques. We prepared
• Feng, Yongjun,He, Ting,Alonso-Vante, Nicolas

• p. 5252 - 5256

  (2009)
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• Hierarchically porous few-layer porphyrinic carbon nanosheets formed by a VO: X-templating method for high-efficiency oxygen electroreduction
• A new vanadium oxide-templating synthesis strategy is used to synthesize porous few-layer porphyrinic carbon nanosheets (PPCNs) with highly efficient electrocatalytic activity for oxygen reduction reaction (ORR). Fe-porphyrin precursors were intercalated into V2O5 layers and directly transformed to carbon nanosheets after pyrolysis. Highly accessible porphyrinic Fe-N4 moieties embedded within few-layer carbon nanosheets with hierarchical porosity and high surface area (1600 m2 g-1) were obtained. The PPCNs were demonstrated as excellent non-precious metal catalysts for ORR in both alkaline and acidic media. Specifically, the PPCNs exhibited a more positive half-wave potential than commercial Pt/C (20 wt%) in an alkaline medium at a lower catalyst loading. Moreover through further pyrolysis treatment, the catalytic activity and durability of PPCNs for ORR in both media could be further improved. The novel synthesis method presented here opens up a new route to creating novel carbon nanomaterials for various applications.
• Kong,Mao,Wang,Lin,Bu,Feng

• p. 7305 - 7312

  (2016)
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• Production of hydrogen peroxide from carbon monoxide, water and oxygen over alumina-supported Ni catalysts
• Novel amorphous Ni-B catalysts supported on alumina have been developed for the production of hydrogen peroxide from carbon monoxide, water and oxygen. The experimental investigation confirmed that the promoter/Ni ratio and the preparation conditions have a significant effect on the activity and lifetime of the catalyst. Among all the catalysts tested, the Ni-La-B/γ-Al 2O3 catalyst with a 1:15 atomic ratio of La/Ni, dried at 120°C, shows the best activity and lifetime for the production of hydrogen peroxide. The deactivation of the alumina-supported Ni-B amorphous catalyst was also studied. According to the characterizations of the fresh and used catalysts by SEM, XRD and XPS, no sintering of the active component and crystallization of the amorphous species were observed. However, it is water poisoning that leads to the deactivation of the catalyst. The catalyst characterization demonstrated that the active component had changed (i.e., amorphous NiO to amorphous Ni(OH)2) and then salt was formed in the reaction conditions. Water promoted the deactivation because the surface transformation of the active Ni species was accelerated by forming Ni(OH) 2 in the presence of water. The formed Ni(OH)2 would partially change to Ni3(PO4)2.
• Ma, Zhong-Long,Jia, Rong-Li,Liu, Chang-Jun

• p. 157 - 163

  (2004)
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• Structural studies on manganese(III) and manganese(IV) complexes of tetrachlorocatechol and the catalytic reduction of dioxygen to hydrogen peroxide
• The mononuclear complexes (Bu4N)[Mn(Cl4Cat) 2(H2O)(EtOH)] and (Bu4N)2[Mn(Cl 4Cat)3] (H2Cat=1,2-dihydroxybenzene) have been synthesised and characterised by X-ray diffraction. This work provides a direct, independent, synthesis of these complexes and an interesting example of how solvent effects can promote the formation of either a manganese(III) or manganese(IV) complex of the same ligand. The characterisation of (Bu 4N)[Mn(Cl4Cat)2(H2O)(EtOH)] supports previous work that manganese(III) is extremely reluctant to form tris (catecholato) complexes due to the short 'bite distance' of catecholate oxygen atoms (2.79 ?) which are unable to span the elongated coordination axes of the Jahn-Teller distorted Mn(III) ion and explains the 2:1 and 3:1 tetrachlorocatechol:manganese ratios in the Mn(III) and Mn(IV) complexes, respectively. Hydrogen peroxide production using dioxygen and hydroxylamine as substrates in acetonitrile/water mixtures, under ambient conditions, can be demonstrated with both complexes, suggesting that neither labile coordination sites nor the oxidation state of the manganese are important to the catalytic system. Turn over frequencies (TOF, moles of H2O2 per moles of manganese per hour) of ～10000 h-1 are obtained and this compares very favourably with the commercial production of hydrogen peroxide by the autoxidation of 2-ethylanthrahydroquinone (AO process).
• Sheriff, Tippu S.,Carr, Pamela,Coles, Simon J.,Hursthouse, Michael B.,Lesin, Jocelyne,Light, Mark E.

• p. 2494 - 2502

  (2004)
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• Porous Carbon-Hosted Atomically Dispersed Iron–Nitrogen Moiety as Enhanced Electrocatalysts for Oxygen Reduction Reaction in a Wide Range of pH
• As one of the alternatives to replace precious metal catalysts, transition-metal–nitrogen–carbon (M–N–C) electrocatalysts have attracted great research interest due to their low cost and good catalytic activities. Despite nanostructured M–N–C catalysts can achieve good electrochemical performances, they are vulnerable to aggregation and insufficient catalytic sites upon continuous catalytic reaction. In this work, metal–organic frameworks derived porous single-atom electrocatalysts (SAEs) were successfully prepared by simple pyrolysis procedure without any further posttreatment. Combining the X-ray absorption near-edge spectroscopy and electrochemical measurements, the SAEs have been identified with superior oxygen reduction reaction (ORR) activity and stability compared with Pt/C catalysts in alkaline condition. More impressively, the SAEs also show excellent ORR electrocatalytic performance in both acid and neutral media. This study of nonprecious catalysts provides new insights on nanoengineering catalytically active sites and porous structures for nonprecious metal ORR catalysis in a wide range of pH.
• Fu, Shaofang,Zhu, Chengzhou,Su, Dong,Song, Junhua,Yao, Siyu,Feng, Shuo,Engelhard, Mark H.,Du, Dan,Lin, Yuehe

• (2018)
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• Crystalline-Water/Coordination Induced Formation of 3D Highly Porous Heteroatom-Doped Ultrathin Carbon Nanosheet Networks for Oxygen Reduction Reaction
• Development of highly efficient electrocatalysts with low cost for oxygen reduction reaction (ORR) is crucial for their application in fuel cells and metal-air batteries. In this work, we report a synthesis of 3D heteroatom-doped ultrathin carbon nanosheet networks directly starting from solid raw materials. This method represents an operationally simple, general, and sustainable strategy to various ultrathin carbon nanosheet networks. Evaporation of crystalline water and coordination interaction are proposed to be responsible for the formation of the 3D carbon nanosheet networks. The carbon nanosheet networks possess high surface area with micro- and macropores, large pore volume, ultrathin nanosheet structure, and effective N/S-co-doping. The as-prepared materials show outstanding electrocatalytic ORR performance with more positive onset potential and half-wave potential, good methanol tolerance, and excellent stability, compared with those of the porous carbons derived from the ZIF counterpart and commercial Pt/C. This work not only provides highly active ORR electrocatalysts via an operationally simple and green process and also demonstrates a general method to prepare 3D ultrathin carbon nanosheet networks without any additional template and solvent.
• Liu, Tingting,Feng, Shi,Huo, Jia,Li, Qiling,Xie, Chao,Wang, Shuangyin

• p. 4562 - 4568

  (2018)
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• Synthesis of hydrogen peroxide in a proton exchange membrane electrochemical reactor
• Humidified oxygen was reduced to hydrogen peroxide at the cathode in a proton exchange membrane electrochemical flow reactor. The optimum conditions for peroxide generation were determined as a function of the applied voltage, electrode materials (gold, graphite, and activated carbon powders), catalyst loadings, reactant flowrates, and pressure. Measured and calculated quantities included cell current, peroxide concentrations, and current efficiencies.
• Tatapudi,Fenton

• p. L55-L57

  (1993)
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• Changes induced by transition metal oxides in Pt nanoparticles unveil the effects of electronic properties on oxygen reduction activity
• Although the relevance of electronic effects in the electrocatalysis of the oxygen reduction reaction has been recognized, the impossibility of separating the effects of composition and particle size for Pt-based materials has hindered establishing clear activity-property relationships. Herein, we report a systematic study based on induced changes via the interactions of pure Pt nanoparticles with transition metal oxide/carbon supports (Pt/MOx/C catalysts, MOx = CeO2, SnO2, TiO2, ZrO2 and WO3). A thorough analysis of aberration-corrected HR-STEM images demonstrated that Pt particles are similar in size and shape for all catalysts, while the direct probing of electronic properties by in situ X-ray absorption spectroscopy evidenced charge transfer between Pt and the supports. This approach allowed ascribing the changes in electrocatalytic activity for oxygen reduction solely to the variations in the electronic vacancy of the Pt 5d band resulting from the interactions between the metal nanoparticles and the supports containing different transition metal oxides. Oxygen reduction was studied in acid and in alkaline solutions, and linear correlations between the kinetic current densities and the Pt 5d band vacancy of pure Pt nanoparticles were found in both media. Possible first steps of the reduction of oxygen are discussed to explain the trends observed. The results, evidencing that enhanced ORR activity on Pt particles is promoted by a lower 5d band vacancy in acid solutions and by a higher one in alkaline medium, provide new insights on the fundamental aspects of oxygen reduction, and open up new possibilities to develop catalysts with enhanced activity for fuel cell cathodes by tuning their electronic properties.
• Ometto, Felipe B.,Carbonio, Emilia A.,Teixeira-Neto, érico,Villullas, Hebe M.

• p. 2075 - 2086

  (2019)
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• Homogeneous Catalysis of the Electrochemical Reduction of Dioxygen by a Macrocyclic Cobalt(III) Complex
• The rotating ring-disk electrode was used to examine the reduction of dioxygen to hydrogen peroxide as catalyzed by the macrocyclic cobalt complex, trans-aneN4)(OH2)2>3+.Two different mechanisms were identified that depended on the ratio of dioxygen to cobalt.With excess cobalt, a well-characterized μ-peroxo complex, trans-aneN4)(OH2))2O2>4+, is formed at potentials where the initial Co(III) complex is reduced.At more negative potentials the μ-peroxo complex is reduced to H2O2 and aneN4)(OH2)2>2+ which re-enters the catalytic cycle.With excess dioxygen, the initial product of the reaction between the Co(II) complex and dioxygen is very rapidly further reduced to form a new complex thought to be trans-aneN4)(OH2)(O2H)>2+, a new, end-bonded, hydroperoxide complex.The hydroperoxide complex is further reduced at more negative potentials to yield H2O2 and aneN4)(OH2)2>2+.The rate of reaction of aneN4)(OH2)2>2+ with dioxygen proved too fast to measure with the rotating ring-disk electrode.The related complex, 4,11-diene N4)(OH2)2>3+, also catalyzes the reduction of dioxygen and at a much more positive potential but at a somewhat lower rate.
• Geiger, Thomas,Anson, Fred C.

• p. 7489 - 7496

  (1981)
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• Spinel CoMn2O4 nanoparticles supported on a nitrogen and phosphorus dual doped graphene aerogel as efficient electrocatalysts for the oxygen reduction reaction
• In this work, we present a novel hybrid composed of spinel CoMn2O4 nanoparticles and a N, P dual-doped graphene aerogel (CoMn2O4/NPGA). The CoMn2O4/NPGA is characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The electrocatalytic activity of the CoMn2O4/NPGA composite towards the ORR was assessed using a linear sweep voltammetry method. Rotating disk electrode (RDE) measurements show that the as-obtained CoMn2O4/NPGA shows excellent ORR activity in an alkaline medium comparable to the benchmark Pt/C catalyst. Electrochemical measurements reveal that the ORR on CoMn2O4/NPGA proceeds through an almost four-electron pathway. Simultaneously, the methanol tolerance and operational stability of CoMn2O4/NPGA toward the ORR are prominently higher than those of commercial Pt/C. All these conspicuous properties suggest that our proposed CoMn2O4/NPGA may be used as a prospective Pt-free catalyst in alkaline direct methanol fuel cells.
• Guo, Wenhui,Ma, Xiuxiu,Zhang, Xianlei,Zhang, Yaqing,Yu, Dingling,He, Xingquan

• p. 96436 - 96444

  (2016)
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• Temperature Dependence of the Reaction HO2+HO2 at Low Pressures
• The temperature dependence of the self-reaction of HO2, HO2+HO2->H2O2+O2 (k1) (1), was investigated by detecting HO2 with laser magnetic resonance in a low-pressure flow tube coated with halocarbon wax.Two independent chemical reactions (CH2OH+O2 and F+H2O2) were used to produce HO2 and two calibration procedures were used to determine the concentration of HO2.With 95percent confidence limits, k1(T)=(2.0+/-0.6)*10-13exp cm3 molecule-1 s-1 for the pressure-independent bimolecular channel of reaction 1 from 253 to 390 K, where -d/dt=2k12.
• Takacs, Gerard A.,Howard, Carleton J.

• p. 687 - 690

  (1986)
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• Room-Temperature Rate Constant for the HO2 + HO2 Reaction at Low Pressures
• The rate constant, k1, for the self-reaction of HO2, HO2 + HO2 -> H2O2 + O2, was investigated in a discharge-flow system at room temperature and low pressures (1-7 torr) of He carrier gas by laser magnetic resonance detection of HO2, OH, and NO2.Three different chemical reactions, F + H2O2, Cl + H2O2, and CH2OH + O2, were used as sources of HO2.Absolute concentrations of HO2 were determined by converting HO2 to OH and NO2, by reaction with NO, and calibrating the system with known concentrations of OH or NO2.The average values for k1 in a phosphoric acid and halocarbon wax-coated flow tube were (1.90 +/- ? = 0.05)E-12 and (1.54 +/- ? = 0.07)E-12 cm3 molecule-1 s-1, respectively, at 295 +/- 2 K, where the errors represent one standard deviation of the mean.These results indicate some effect from reactor surface coating.The recommended rate constant from this study is k1 = (1.5 +/- 0.3)E-12 cm3 molecule-1 s-1, where the error is at the 95percent confidence level and includes an estimate of systematic errors.This result combined with other recent studies indicates that the reaction has both pressure-independent and pressure-dependent mechanisms.
• Takacs, Gerald A.,Howard, Carleton J.

• p. 2110 - 2116

  (1984)
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• Oxygen Reduction with Hydroxy-1,4-naphthoquinones immobilized at Carbon Electrodes
• Oxygen reduction with naphthazarin (5,8-dihydroxy-1,4-naphthoquinone) has been studied by cyclic voltammetry and by flow-through electrolysis.The mechanisms of oxygen reduction were studied thermodynamically.At pH 7 the semiquinone anion is the most likel
• Nagaoka, Tsutomu,Sakai, Toshiaki,Ogura, Kotaro,Yoshino, Takashi

• (1987)
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• Electrocatalytic reduction of dioxygen by Mn(iii): Meso -tetra(N -methylpyridinium-4-yl)porphyrin in universal buffer
• The electrochemical characterization of manganese(iii) meso-tetra(N-methylpyridinium-4-yl)porphyrin pentachloride ([Mn(TMPyP)Cl][Cl]4) via cyclic voltammetry (CV) and UV-vis spectroelectrochemistry (UV-vis SEC) was performed across the entire p
• Lieske, Lauren E.,Hooe, Shelby L.,Nichols, Asa W.,MacHan, Charles W.

• p. 8633 - 8641

  (2019)
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• Calmagite dye oxidation using in situ generated hydrogen peroxide catalysed by manganese(ii) ions
• Hydrogen peroxide (H2O2) generated from the manganese(ii) catalysed reduction of dioxygen has been shown to efficiently oxidize Calmagite (3-hydroxy-4-(2-hydroxy-5-methylphenylazo)naphthalene-1- sulfonic acid) in aqueous solution at
• Sheriff, Tippu S.,Cope, Steven,Ekwegh, Mmaezi

• p. 5119 - 5122

  (2007)
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• Key Single-Atom Electrocatalysis in Metal—Organic Framework (MOF)-Derived Bifunctional Catalysts
• Metal–organic framework (MOF)-derived materials have attracted increasing interest and show promising catalytic performances in many fields. Intensive efforts have been focused on the structure design and metal-site integration in MOF-derived catalysts. However, the key catalytic processes related with the metal sites in MOF-derived catalysts that dominate the electrocatalytic performance still remain obscure. Herein, we show a neglected but critical issue in the pyrolytic synthesis of MOF-derived catalysts: the coupled evolution of dual sites, that is, metallic sites and single-atom metal sites. The identification of active sites of single-atom sites from the visible particles has been elucidated through the combined X-ray spectroscopic, electron microscopic, and electrochemical studies. Interestingly, after a total removal of metallic cobalt sites, catalysts with purified single-atom metal sites show no faltering activity for either the oxygen reduction reaction (ORR) or hydrogen evolution reaction (HER), while significantly enhanced ORR selectivity is achieved; this reveals the dominant activity and selectivity contribution from single-atom electrocatalysis. The insight of the coupled evolution of dual sites and the as-demonstrated dual-site decoupling strategies open up a new routine for the design and synthesis of MOF-derived catalysts with the optimized single-atom electrocatalysis towards various electrochemical reactions.
• Zhao, Wanpeng,Wan, Gang,Peng, Chunlei,Sheng, Huaping,Wen, Jianguo,Chen, Hangrong

• p. 3473 - 3479

  (2018)
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• Application of chemiluminescent probe to monitoring superoxide radicals and hydrogen peroxide in TiO2 photocatalysis
• A chemiluminescent probe, luminol, was successfully applied to monitoring Superoxide ions (O2?-) and hydrogen peroxide (H2O2) produced on photocatalytic reaction in aqueous TiO2 suspension. Two chemiluminescent reactions were distinguished from the decay profile after the end of the irradiation, and the reaction mechanism was analyzed. The fast decay component gives information about O2?- and the slow one provides the amount of H2O2. The rate constant for the reaction of O2?- with luminol was found to be 1 x 104 M-1 s-1. The amount of O2?- during the irradiation on TiO2 in alkaline solution could be estimated to be on the order of 10-13 M. Detection of H2O2 in concentrations as small as 10-9 M was demonstrated in the photocatalytic water oxidation.
• Nosaka, Yoshio,Yamashita, Yoshifumi,Fukuyama, Hiroshi

• p. 5822 - 5827

  (1997)
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• Tris(2,2'-bipyridine)ruthenium(II)-photosensitized Reductions of Methyl Viologen and Molecular Oxygen in a Network of Water-swollen Cation-exchange Resin
• The visible-light-induced reduction of methyl viologen was found to occur in water-swollen cation-exchange resin, which adsorbed both Ru(bpy)32+ and methyl viologen (RMCA resin) with the aid of triethanolamine (TEA) as a donor.With illumination, the generation of hydrogen peroxide procceds in an oxygenated TEA solution containing RMCA resin.Hydrogen peroxide is produced via the superoxide ion, which is itself formed by the reaction of methyl viologen radical in the resin with the oxygen molecule in the bulk of the solution.The Ru(bpy)32+-photosensitized reaction processes leading to the generation of methyl viologen radical and hydrogen peroxide in the heterogeneous systems are discussed on the basis of the results obtained.
• Kurimura, Yoshimi,Katsumata, Kimiyo

• p. 2560 - 2563

  (1982)
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• Evidence for the role of colloidal palladium in the catalytic formation of H2O2 from H2 and O2
• The direct production of H2O2 from H2 and O2 (O2/H2 = 2) at 25°C and 760 Torr occurs in an aqueous phase over colloidal palladium that may be introduced either via PdCl2 or via Pd supported on silica gel (Pd/SiO2). In the latter case, aqueous HCl facilitates the dissolution of the supported Pd. The presence of colloidal palladium was confirmed by electron microscopy. When the solution was either 0.1 M or 1.0 M in HCl, removal of the silica, along with any remaining supported Pd, did not affect the rate of H2O2 formation because the amount of active colloidal Pd remained unchanged. The specific activity of the supported Pd is only 3% of that for colloidal Pd, probably because of transport limitations within the pores of the silica.
• Dissanayake, Dhammike P.,Lunsford, Jack H.

• p. 173 - 176

  (2002)
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• Factors that control catalytic two-versus four-electron reduction of dioxygen by copper complexes
• The selective two-electron reduction of O2 by one-electron reductants such as decamethylferrocene (Fc*) and octamethylferrocene (Me8Fc) is efficiently catalyzed by a binuclear Cu(II) complex [CuII2(LO)(OH)]2+ (D1) {LO is a binucleating ligand with copper-bridging phenolate moiety} in the presence of trifluoroacetic acid (HOTF) in acetone. The protonation of the hydroxide group of [CuII2(LO)(OH)]2+ with HOTF to produce [CuII2(LO)(OTF)]2+ (D1-OTF) makes it possible for this to be reduced by 2 equiv of Fc* via a two-step electron-transfer sequence. Reactions of the fully reduced complex [Cu I2(LO)]+ (D3) with O2 in the presence of HOTF led to the low-temperature detection of the absorption spectra due to the peroxo complex [CuII2(LO)(OO)] (D) and the protonated hydroperoxo complex [CuII2(LO)(OOH)] 2+ (D4). No further Fc* reduction of D4 occurs, and it is instead further protonated by HOTF to yield H2O2 accompanied by regeneration of [CuII2(LO)(OTF)] 2+ (D1-OTF), thus completing the catalytic cycle for the two-electron reduction of O2 by Fc*. Kinetic studies on the formation of Fc*+ under catalytic conditions as well as for separate examination of the electron transfer from Fc* to D1-OTF reveal there are two important reaction pathways operating. One is a rate-determining second reduction of D1-OTF, thus electron transfer from Fc * to a mixed-valent intermediate [CuIICu I(LO)]2+ (D2), which leads to [CuI 2(LO)]+ that is coupled with O2 binding to produce [CuII2(LO)(OO)]+ (D). The other involves direct reaction of O2 with the mixed-valent compound D2 followed by rapid Fc* reduction of a putative superoxo-dicopper(II) species thus formed, producing D.
• Fukuzumi, Shunichi,Tahsini, Laleh,Lee, Yong-Min,Ohkubo, Kei,Nam, Wonwoo,Karlin, Kenneth D.

• p. 7025 - 7035

  (2012)
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• Electrocatalytic dioxygen reduction on underpotentially deposited Pb on Au(111) studied by an active site blocking strategy
• Electrochemical measurements and in situ scanning tunneling microscopy (STM) were carried out to establish a structure-reactivity correlation for peroxide or dioxygen reduction on underpotentially deposited (upd) Pb on Au(111) in 0.1 M HClO4. STM imaging revealed the presence of Pb islands with height of 0.25 ± 0.05 nm at the potential of highest catalytic activity toward the O2 and H2O2 reduction. The full Pb monolayer formed at - 0.03 v vs. NHE showed about half the activity of the Pb islands. Ethanethiol (EtSH) considerably, but not completely, inhibited H2O2 reduction activity of the Pb island structure. EtSH introduction resulted in the formation of a 0.13-nm-high terrace along the edges of the Pb islands, which was assigned to EtSH bound to the Au surface near the Pb islands with the alkyl chain oriented roughly perpendicular to the surface. These results showed that edge sites around the Pb island were the active site of catalysis, though the sites atop the Pb islands might also take part in catalytic O2 reduction by Pb upd on Au(111).
• Oh, Ilwhan,Gewirth, Andrew A.,Kwak, Juhyoun

• p. 17 - 22

  (2003)
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• Photoassisted Construction of Holey Defective g-C3N4 Photocatalysts for Efficient Visible-Light-Driven H2O2 Production
• Holey defective g-C3N4 photocatalysts, which are easily prepared via a novel photoassisted heating process, are reported. The photoassisted treatment not only helps to create abundant holes, endowing g-C3N4 with more exposed catalytic active sites and crossplane diffusion channels to shorten the diffusion distance of both reactants from the surface to bulk and charge carriers from the bulk to surface, but also introduces nitrogen vacancies in the tri-s-triazine repeating units of g-C3N4, inducing the narrowing of intrinsic bandgap and the formation of defect states within bandgap to extend the visible-light absorption range and suppress the radiative electron–hole recombination. As a result, the holey defective g-C3N4 photocatalysts show much higher photocatalytic activity for H2O2 production with optimized enhancement up to ten times higher than pristine bulk g-C3N4. The newly developed synthetic strategy adopted here enables the sufficient utilization of solar energy and shows rather promising for the modification of other materials for efficient energy-related applications.
• Shi, Li,Yang, Liuqing,Zhou, Wei,Liu, Yanyu,Yin, Lisha,Hai, Xiao,Song, Hui,Ye, Jinhua

• (2018)
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• Rate constant measurements for the reaction of HO2 with O3 from 200 to 300 K using a turbulent flow reactor
• The rate constant for the reaction of HO2 with O3 was measured using a turbulent flow reactor with tunable diode laser absorption detection of HO2. Two separate methods were used to determine k1 from the pseudo-first-order decay of HO2 in excess O3. The isotopic labeling method used H18O2 in excess 16O3 to avoid reformation of the reactant. The OH scavenger method used trifluorochloroethylene to remove the OH product and prevent re-formation of HO2. The turbulent flow reactor allowed measurements at temperatures between 297 and 197 K at total pressures from 80 to 175 Torr, spanning a wide range of stratospheric conditions. The temperature-dependent rate constant is given by the three-term expression k1(T) = {(103 ± 57) exp[-(1323 ± 160)77] + 0.88} × 10-15 cm3 molecule-1 s-1, reflecting its non-Arrhenius behavior at low temperatures. These results demonstrate that the catalytic destruction of lower stratospheric O3 by HOx radicals (OH and HO2) may proceed faster than current models predict. The rate constant at 295 K is (2.0 ± 0.2) × 10-15 cm3 molecule-1 s-1.
• Herndon, Scott C.,Villalta, Peter W.,Nelson, David D.,Jayne, John T.,Zahniser, Mark S.

• p. 1583 - 1591

  (2001)
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• The screening of metal ion inhibitors for glucose oxidase based on the peroxidase-like activity of nano-Fe3O4
• In this study, a colorimetric method is proposed based on the peroxidase-like activity of Fe3O4 magnetic nanoparticles for screening metal ion inhibitors for glucose oxidase activity. First, the glucose oxidase was typically used as a specific enzyme to catalyze the oxidation of β-d-glucose resulting in the generation of hydrogen peroxide. Next, having an inherent peroxidase-like activity, Fe3O4 magnetic nanoparticles were adopted as the catalyst. Then, the generated H2O2 was capable of participating in the oxidation of 3,3′,5,5′-tetramethylbenzidine to yield a blue colored product. Based on the above results, an in vitro screen model of metal ion inhibitors of glucose oxidase was thus established. Metal ions including Ca2+, Pb2+, Mn2+, Ag+, Al3+, Cu2+, Mg2+ and Zn2+ have been tested. Herein, towards the glucose oxidase activity, Ca2+, Pb2+, Mg2+ and Mn2+ showed no effect while Al3+ and Zn2+ displayed a slight activation, while of Ag+ and Cu2+ expressed a strong inhibition. The further detection of Ag+ and Cu2+ manifested that their IC50 were 0.662 μmol L-1 and 12.619 μmol L-1, respectively. The entire detection process could be accomplished within 15 min. This assay is economical, time-saving and highly-effective with definitely significant reference for the screening of metal ions as glucose oxidase inhibitors.
• Wu, Yao-Hui,Chu, Lei,Liu, Wen,Jiang, Lun,Chen, Xiao-Yong,Wang, Yong-Hong,Zhao, Yun-Lin

• p. 47309 - 47315

  (2017)
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• Direct formation of H2O2 from H2 and O2 over a Pd/SiO2 catalyst: The roles of the acid and the liquid phase
• The direct formation of H2O2 from H2 and O2 was carried out over a Pd/SiO2 catalyst in a medium of ethanol or water acidified with either H2SO4 or HCl. The H2SO4/ethanol system is the most favorable for peroxide formation. Both the proton and the anion, in the case of Cl-, promote the net formation of the peroxide. Protons inhibit the reduction of H 2O2 by H2, and chloride ions limit the direct reduction of O2 to water, presumably by blocking Pd ensembles. Sulfate ions, being noncoordinating ligands, do not serve this function; therefore the H2SO4/water system is a poor medium for producing the peroxide. By contrast, the H2SO4/ethanol system is believed to be effective because in the presence of O2, acetate ions are formed from ethanol, and these ions block Pd ensembles in the same manner as chloride ions.
• Han, Yi-Fan,Lunsford, Jack H.

• p. 313 - 316

  (2005)
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• Theoretical Modelling and Facile Synthesis of a Highly Active Boron-Doped Palladium Catalyst for the Oxygen Reduction Reaction
• A highly active alternative to Pt electrocatalysts for the oxygen reduction reaction (ORR), which is the cathode-electrode reaction of fuel cells, is sought for higher fuel-cell performance. Our theoretical modelling reveals that B-doped Pd (Pd-B) weakens the absorption of ORR intermediates with nearly optimal binding energy by lowering the barrier associated with O2dissociation, suggesting Pd-B should be highly active for ORR. In fact, Pd-B, facile synthesized by an electroless deposition process, exhibits 2.2times and 8.8times higher specific activity and 14times and 35times less costly than commercial pure Pd and Pt catalysts, respectively. Another computational result is that the surface core level of Pd is negatively shifted by B doping, as confirmed by XPS, and implies that filling the density of states related to the anti-bonding of oxygen to Pd surfaces with excess electrons from B doping, weakens the O bonding to Pd and boosts the catalytic activity. Better with a B in its bonnet: Theoretical modelling shows that B doping negatively shifts the surface core level of Pd and lowers the barrier to O2dissociation for the oxygen reduction reaction (ORR). A B-doped Pd nanoparticle catalyst was then rationally designed, synthesized in a facile manner by electroless deposition, and shown to be a highly active ORR catalyst compared to commercial Pd and Pt catalysts.
• Vo Doan, Tat Thang,Wang, Jingbo,Poon, Kee Chun,Tan, Desmond C. L.,Khezri, Bahareh,Webster, Richard D.,Su, Haibin,Sato, Hirotaka

• p. 6842 - 6847

  (2016)
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• Electrocatalytic O2 Reduction by [Fe-Fe]-hydrogenase active site models
• The instability of [Fe-Fe]-hydrogenase and its synthetic models under aerobic conditions is an inherent challenge in their development as practical H2 producing electrodes. The electrochemical oxygen reduction reaction of a series of synthetic model complexes of the [Fe-Fe] hydrogenase is investigated, and a dominant role of the bridgehead nitrogen in reducing the amount of partially reduced oxygen species (PROS), which is detrimental to the stability of these complexes, is discovered.
• Dey, Subal,Rana, Atanu,Crouthers, Danielle,Mondal, Biswajit,Das, Pradip Kumar,Darensbourg, Marcetta Y.,Dey, Abhishek

• p. 8847 - 8850

  (2014)
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• Activation of O2 by Organosilicon Reagents Yields Quantitative Amounts of H2O2 or (Me3Si)2O2 for Efficient O-Transfer Reactions
• Molecular oxygen is kinetically inert and rarely used as a primary oxidant for low temperature selective oxygenation reactions. Here, we show that O2 is converted into H2O2 in almost quantitative yields (98 %) at ambient temperature and atmospheric pressure in the presence of bis(trimethylsilyl)-1,4-cyclohexadiene 1. Similarly, the reaction of O2 with dihydro-bis(trimethylsilyl) viologen 2 and pyrazine 3 yields bis(trimethylsilyl) peroxide (BTSP) in excellent yields (up to 99 %) at low temperature. Both processes demonstrate that readily available organosilicon reagents enable chemistry typically observed with mono-oxygenase co-enzymes, such as FADH2 and FMNH2, in biological systems, or at higher pressure via the industrial anthraquinone process. This efficient synthesis of H2O2 and BTSP directly from O2 is particularly attractive for the preparation of the corresponding O-17 and O-18 labeled reagents without the need of large excess amounts of O2. These are showcased in O-atom transfer reactions to various organic or inorganic substrates, in a two-step one-pot process, making the rapid and on-demand synthesis of large libraries of O-labeled compounds readily possible.
• Yamamoto, Keishi,Tanaka, Shinji,Hosoya, Hiromu,Tsurugi, Hayato,Mashima, Kazushi,Copéret, Christophe

• (2018)
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• Effect of copper ions on the formation of hydrogen peroxide from photocatalytic titanium dioxide particles
• Reactive radicals such as hydroxyl radical (OH.), hydrogen peroxide (H2O2), and superoxide anion (O2 -) are the main power driving titanium dioxide (TiO2) photocatalytic reactions, for example, photokilling of biological cells. Here, the effect of copper ions on the formation of H2O2 over photocatalytic TiO2 was investigated. Under an oxygen-purged solution, formation of H2O2 was increased dramatically up to 20 times by the addition of a small amount of copper ions. By using the Fenton reaction, the H2O2 formed can be converted into OH., a highly reactive radical. In contrast, under nitrogen-purged solution, no H2O2 was formed even in the presence of an electron acceptor, silver ion (Ag+). These results clearly show that H2O2 was generated from the reduction site of the photoexcited TiO2 and indicate an effective way to increase the photocatalytic efficiency.
• Cai, Ruxiong,Kubota, Yoshinobu,Fujishima, Akira

• p. 214 - 218

  (2003)
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• Production of Hydrogen Peroxide from Dioxygen and Hydroxylamine or Hydrazine catalysed by Manganese Complexes
• Manganese(II) catecholate complexes efficiently catalyse the production of H2O2 from dioxygen in the range pH 7.5-8.6 using hydroxylamine or hydrazine as substrates: concentrations of hydrogen peroxide >0.2 mol dm-3 and turnover numbers /II> > 104 can be obtained.The rate of production and yields are very sensitive to the electronic effect of the substituents on the catecholate ring with the best results being achieved using 4,5-dihydroxybenzene-1,3-disulfonate.Deuteriation studies (using ND2OD) indicated that the reduction of O2 occurs via an electron trans fer from the substrate and a mechanism is proposed whereby both O2 and thec substarte become bound to manganese and the electron transfer is mediated through the manganese catecholate complex.
• Sheriff, Tippu S.

• p. 1051 - 1058

  (1992)
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• Oscillatory reactions Am(VI) ? Am(V) under ozonation of Am(OH) 3 suspension in bicarbonate solution
• During prolonged ozonation of Am(III) hydroxide in bicarbonate solutions, oscillatory Am(VI) ? Am(IV) reactions were observed. Substitution of 241Am with 243Am, which is characterized by substantially lower specific radioactivity, does not change the character and parameters of the oscillatory process: the yields of 241Am and 243Am, and the oscillation period of about 2 min do not differ noticeably. The results suggest that the reductants in the system mainly originate from the ozone decomposition products; the arising hydroperoxy radicals and hydrogen peroxide partially reduce Am(VI) in the solution. The Am(VI) yield in ozonation of the Am(OH)3 suspension in a bicarbonate solution substantially decreases with increasing the initial americium content.
• Nikonov,Gogolev,Tananaev,Myasoedov

• p. 246 - 248

  (2004)
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• The Solid-Phase Synthesis of an Fe-N-C Electrocatalyst for High-Power Proton-Exchange Membrane Fuel Cells
• The environmentally friendly synthesis of highly active Fe-N-C electrocatalysts for proton-exchange membrane fuel cells (PEMFCs) is desirable but remains challenging. A simple and scalable method is presented to fabricate FeII-doped ZIF-8, which can be further pyrolyzed into Fe-N-C with 3 wt % of Fe exclusively in Fe-N4 active moieties. Significantly, this Fe-N-C derived acidic PEMFC exhibits an unprecedented current density of 1.65 A cm?2 at 0.6 V and the highest power density of 1.14 W cm?2 compared with previously reported NPMCs. The excellent PEMFC performance can be attributed to the densely and atomically dispersed Fe-N4 active moieties on the small and uniform catalyst nanoparticles.
• Liu, Qingtao,Liu, Xiaofang,Zheng, Lirong,Shui, Jianglan

• p. 1204 - 1208

  (2018)
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• Control of Electrons' Spin Eliminates Hydrogen Peroxide Formation during Water Splitting
• The production of hydrogen through water splitting in a photoelectrochemical cell suffers from an overpotential that limits the efficiencies. In addition, hydrogen-peroxide formation is identified as a competing process affecting the oxidative stability of photoelectrodes. We impose spin-selectivity by coating the anode with chiral organic semiconductors from helically aggregated dyes as sensitizers; Zn-porphyrins and triarylamines. Hydrogen peroxide formation is dramatically suppressed, while the overall current through the cell, correlating with the water splitting process, is enhanced. Evidence for a strong spin-selection in the chiral semiconductors is presented by magnetic conducting (mc-)AFM measurements, in which chiral and achiral Zn-porphyrins are compared. These findings contribute to our understanding of the underlying mechanism of spin selectivity in multiple electron-transfer reactions and pave the way toward better chiral dye-sensitized photoelectrochemical cells.
• Mtangi, Wilbert,Tassinari, Francesco,Vankayala, Kiran,Vargas Jentzsch, Andreas,Adelizzi, Beatrice,Palmans, Anja R. A.,Fontanesi, Claudio,Meijer,Naaman, Ron

• p. 2794 - 2798

  (2017)
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• Effect of acid-leaching on carbon-supported copper phthalocyanine tetrasulfonic acid tetrasodium salt (CuTSPc/C) for oxygen reduction reaction in alkaline electrolyte: Active site studies
• Although non-precious metal catalysts (NPMCs) have been extensively studied as low-cost catalyst alternatives to Pt, in particular for the oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells (PEMFCs), the nature of the active ORR catalytic sites is still a subject of controversy. In this work, using carbon-supported copper phthalocyanine tetrasulfonic acid tetrasodium salt (CuTSPc/C) nanoparticles as the target catalyst, the effects of the transition metal Cu on the ORR active sites are systematically studied using both rotating disk electrode (RDE) and rotating ring disk electrode (RRDE) techniques in alkaline electrolyte. The results show that acid-leaching can significantly decrease the ORR activity of the CuTSPc/C catalyst, with the half-wave potential negatively shifted by more than 50 mV compared to the catalyst before acid-leaching. The electron transfer number of the ORR process catalyzed by the catalyst before acid-leaching remained at about 3.85 over the whole tested potential range from -0.6 to -0.1 V, while this number greatly decreased from 3.82 at -0.55 V to 3.53 at -0.1 V after acid-leaching. The H2O2 produced accordingly increased sharply from 7.8% to 22%. XRD and TEM results indicate that acid-leaching is an effective method to remove metal-Cu. XPS analysis reveals that metal-Cu is essential in the ORR active site structure, and also plays a key part in the stabilization of the active N and S species.
• Zhang, Qing,Zhu, Taishan,Qing, Xin,Qiao, Jinli,Sun, Shuhui

• p. 50344 - 50352

  (2015)
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• Oxygen reduction on nanocrystalline ruthenia-local structure effects
• Nanocrystalline ruthenium dioxide and doped ruthenia of the composition Ru1-xMxO2 (M = Co, Ni, Zn) with 0 ≤ x ≤ 0.2 were prepared by the spray-freezing freeze-drying technique. The oxygen reduction activity and selectivity of the prepared materials were evaluated in alkaline media using the RRDE methodology. All ruthenium based oxides show a strong preference for a 2-electron oxygen reduction pathway at low overpotentials. The catalysts' selectivity shifts towards the 4-electron reduction pathway at high overpotentials (i.e. at potentials below 0.4 V vs. RHE). This trend is particularly noticeable on non-doped and Zn-doped catalysts; the materials containing Ni and Co produce a significant fraction of hydrogen peroxide even at high overpotentials. The suppression of the 4-electron reduction pathway on Ni and Co-doped catalysts can be accounted for by the presence of the Ni and Co cations in the cus binding sites as shown by the DFT-based analyses on non-doped and doped catalysts. This journal is
• Abbott, Daniel F.,Mukerjee, Sanjeev,Petrykin, Valery,Bastl, Zdenk,Halck, Niels Bendtsen,Rossmeisl, Jan,Krtil, Petr

• p. 1235 - 1243

  (2015)
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• Enhancement of H2O2 production and AYR degradation using a synergetic effect of photo-electrocatalysis for carbon nanotube/g-C3N4 electrodes
• In this work, a new gas diffusion electrode (GDE) of carbon nanotube/graphitic carbon nitride (CNT/g-C3N4) was prepared, which enables the substantially improved production of H2O2 (up to 1083.54 mg L-1) compared to generation without g-C3N4 (400 mg L-1). Characterized by TEM, XRD and XPS, the synthesized g-C3N4 was proved to be a thin layer sheet with low defects. Important cathode manufacturing parameters including the mass ratio of CNTs to g-C3N4 were optimized, and the dependence of H2O2 generation on pH, current density, aeration rate and performance stability were investigated. Further explored by linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) analysis, the presence of g-C3N4 was found to accelerate the electron transfer rate, benefit the oxygen surface reaction, which contributed to the enhanced performance for H2O2 production. Finally, such a CNT/g-C3N4 cathode demonstrated effectiveness for the degradation of alizarin yellow R (AYR) by electro-Fenton (EF), photo-Fenton (PF) and photoelectron-Fenton (PEF) processes. AYR was degraded completely, and 94.8% of the organic carbon was removed, which is more than 5 times the amount removed using PF degradation only. And during the PEF degradation process of AYR, electro- and photocatalysis support and optimize each other, which produces a substantial synergistic effect, proving great potential for practical application in organic wastewater treatment.
• Yu, Fangke,Wang, Yi,Ma, Hongrui,Chen, Yang

• p. 16703 - 16708

  (2018)
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• Photochemistry of Solid Ozone
• Samples of neat solid ozone and ozone trapped in excess ice have been subjected to laser photolysis at 308 nm.Cross sections for photoabsorption and photodestruction of the ozone are reported.The quantum yield decreases from 1.5 +/- 0.2 in pure ozone to 0.4 +/- 0.2 for ozone in excess ice.These yields are consistent with a reaction mechanism in which electronically excited O(1D) atoms are responsible for the photochemistry.In neat ozone, the atoms react with a neighboring ozone molecule to form two oxygen molecules.In water, O(1D) reacts to form hydrogen peroxide, HCOOH.Ground-state oxygen atoms produced in the initial photolysis of ozone most likely undergo recombination with O2 to regenerate O3.
• Sedlacek, Arthur J.,Wight, Charles A.

• p. 509 - 511

  (1989)
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• Surface Reorganization on Electrochemically-Induced Zn–Ni–Co Spinel Oxides for Enhanced Oxygen Electrocatalysis
• Herein, we highlight redox-inert Zn2+ in spinel-type oxide (ZnXNi1?XCo2O4) to synergistically optimize physical pore structure and increase the formation of active species on the catalyst surface. The presence of Zn2+ segregation has been identified experimentally and theoretically under oxygen-evolving condition, the newly formed VZn?O?Co allows more suitable binding interaction between the active center Co and the oxygenated species, resulting in superior ORR performance. Moreover, a liquid flow Zn–air battery is constituted employing the structurally optimized Zn0.4Ni0.6Co2O4 nanoparticles supported on N-doped carbon nanotube (ZNCO/NCNTs) as an efficient air cathode, which presents remarkable power density (109.1 mW cm?2), high open circuit potential (1.48 V vs. Zn), excellent durability, and high-rate performance. This finding could elucidate the experimentally observed enhancement in the ORR activity of ZnXNi1?XCo2O4 oxides after the OER test.
• Liu, Zhao-Qing,Ouyang, Ting,Wang, Ling,Wang, Xiao-Tong,Zhong, Jia-Huan

• p. 6492 - 6499

  (2020)
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• Hydrogen Abstraction and One-Electron Oxidation in Nickel(II)-Iminodiacetate Complexes
• Reactions of nickel(II) iminodiacetates with OH radicals in aqueous solutions were studied by means of steady-state and pulse radiolysis.Radiolytic degradation of the complexes led to the formation of glycine and carbonyl compounds with similar yields.The OH radical attacks the metal complexes at the ligand rather than at the metal center, the product being a metal-coordinated radical.This carbon-centered radical undergoes disproponation into products.It may be also oxidized by O2 and Fe(CN)63-.In the presence of N2O the radical initiates a chain reaction in the case of the 1:1 complex but not with the 1:2 complex or the free ligand.Unlike OH, Br2- attacks the metal center rather than the ligand and oxidizes it to the NiIII complexes.This reaction is followed by oxidation of the carboxyl group of the ligby the NiIII to result in decarboxylation and production of formaldehyde.
• Bhattacharyya, S. N.,Saha, N. C.,Neta, P.

• p. 300 - 305

  (1981)
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• Nitrogen-Doped Porous Carbon Cages for Electrocatalytic Reduction of Oxygen: Enhanced Performance with Iron and Cobalt Dual Metal Centers
• Heteroatom-doped carbon materials are promising electrocatalysts towards the oxygen reduction reaction (ORR). In this study, dual metals (Fe an Co) and nitrogen-codoped porous carbon cages (CHS?FeCo) were synthesized by controlled pyrolysis of silica nanoparticle-supported melamine-formaldehyde resin embedded with iron and cobalt precursors, followed by acid etching. Transmission electron microscopy measurements confirmed the formation of hollow carbon cages, and the absence of metal (oxide) nanoparticles suggested atomic dispersion of the metal species within the mesoporous carbon skeletons. X-ray photoelectron spectroscopic analysis revealed a composition of mostly carbon, oxygen, and nitrogen, with ca. 1 % metals. Electrochemically, the dual-metal ones showed a significant enhancement of the catalytic performance towards ORR in alkaline media, as compared to samples with single or no metal dopants. This was accounted for by the synergistic interaction between the Fe and Co centers in the carbon samples, as evidenced in X-ray absorption spectroscopic studies. Remarkably, the CHS?FeCo sample exhibited apparent resistance against KSCN poisoning, where XPS analysis revealed oxidation of KSCN and no metal-sulfur interaction, in sharp contrast to the Fe counterpart which was easily poisoned. Results from this study suggest that the synergistic interactions between dual metal centers may be exploited for enhanced ORR performance of carbon-based nanocomposite catalysts.
• Mercado, Rene,Wahl, Carolin,En Lu, Jia,Zhang, Tianjun,Lu, Bingzhang,Zhang, Peng,Lu, Jennifer Q.,Allen, A'Lester,Zhang, Jin Z.,Chen, Shaowei

• p. 3230 - 3239

  (2020)
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• Direct fabrication of tri-metallic PtPdCu tripods with branched exteriors for the oxygen reduction reaction
• Design of multi-metallic nanocrystals with branched structures is very important for catalytic applications. Herein, a one-step synthesis of unique tri-metallic PtPdCu tripods with branched exteriors (PtPdCu TPs) in an aqueous solution is presented. Benefiting from their spatially and locally separated branches and tri-metallic compositions, the PtPdCu TPs exhibit superior activity and durability for the oxygen reduction reaction. The newly designed PtPdCu TPs are quite different from previous tripods in their branched exteriors. The developed one-step method is very feasible for the preparation of Pt-based multi-metallic tripods with designed compositions and desired performances.
• Wang, Hongjing,Yin, Shuli,Xu, You,Li, Xiaonian,Alshehri, Abdulmohsen Ali,Yamauchi, Yusuke,Xue, Hairong,Kaneti, Yusuf Valentino,Wang, Liang

• p. 8662 - 8668

  (2018)
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• Direct synthesis of hydrogen peroxide from H2 and O2 using TiO2-supported Au-Pd catalysts
• The direct synthesis of H2O2 at low temperature (2 °C) from H2 and O2 using TiO2-supported Au, Pd, and Au-Pd catalysts is discussed. The Au-Pd catalysts performed significantly better than the pure Pd/TiO2 and Au/TiO2 materials. Au-Pd particles were found with a core-shell structure, with Pd concentrated on the surface. The highest yields of H2O2 were observed with uncalcined catalysts, but these were particularly unstable, losing both metals during use. In contrast, samples calcined at 400 °C were stable and could be reused several times without loss of performance. These catalysts exhibited low activity for CO oxidation at 25 °C; conversely, catalysts effective for low-temperature CO oxidation were inactive for H 2 oxidation to H2O2. This anticorrelation is explored in terms of the mechanism by which the catalysts function and the design of catalysts for the selective oxidation of one of these substrates in the presence of the other.
• Edwards, Jennifer K.,Solsona, Benjamin E.,Landon, Philip,Carley, Albert F.,Herzing, Andrew,Kiely, Christopher J.,Hutchings, Graham J.

• p. 69 - 79

  (2005)
• Read Online

• A sol-gel pretreatment combined strategy for constructing cobalt-embedded and nitrogen-doped carbon matrix with high-density active sites as bifunctional oxygen reduction and evolution electrocatalysts
• Developing highly efficient bifunctional oxygen electrocatalysts via cost-effective methods is of great significance for energy storage and conversion systems but still full of challenges. In this work, a simple and eco-friendly method which involves a sol-gel pretreatment on multiple precursors and subsequent pyrolysis is designed to synthesize Co nanoparticles embedded and nitrogen-doped porous carbon (Co@NC). The sol-gel pretreatment ensures the high dispersion of all precursors, which is beneficial to the formation of uniform and highly dense active sites. After pyrolysis, acid treatment removes the unencapsulated Co nanoparticles on the surface to form porous structure and increase the mass activity. Benefiting from the synthetic strategy, the porous Co@NC-850 with large surface area, high density of active sites (graphitic N, pyridinic N and Co-Nx) exhibits comparable oxygen reduction performance (E1/2 = 0.85 V vs. reversible hydrogen electrode) to that of commercial Pt/C and better oxygen evolution activity (with an overpotential of 350 mV at 10 mA cm?2) with respect to RuO2. The potential gap ΔE (between the oxygen evolution potential at 10 mA cm?2 and oxygen reduction E1/2) for Co@NC-850 is only 0.73 V. Compared with the state-of-the-art bifunctional oxygen electrocatalysts, Co@NC-850 shows obvious advantages in bifunctional activity and durability. The results in the present work will shed light on the development of other carbonaceous materials as the bifunctional oxygen electrocatalysts for energy storage and electrochemical devices.
• Liu, Huiling,Wang, Cheng,Wang, Depeng,Zuo, Xintao

• (2021)
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• Copper(I)/O2 chemistry with imidazole containing tripodal tetradentate ligands leading to μ-1,2-peroxo-dicopper(II) species
• Cuprous and cupric complexes with the new imidazolyl containing tripodal tetradentate ligands {LMlm, (1 H-imidazol4-yl)-N,N-bis((pyridin-2-yl) methyl)methanamine, and LElm, 2-(1 H-imidazol-4-yl)-N,N-bis((pyridin- 2-yl)methyl)ethanami

• p. 11297 - 11309

  (2009)
• Read Online

• Biphenyl appended non-noble metal complexes as electrocatalysts for the electrochemical oxygen reduction reaction
• The oxygen reduction reaction (ORR) is one of the most important reactions in many electrochemical processes. There has been a growing interest in the replacement of noble metal electrocatalysts for oxygen reduction reaction (ORR). In continuation of these efforts herein we report the design and synthesis of biphenyl appended non-noble transition metal and Zn(II) complexes as electrocatalysts in the aforementioned reaction. In this regard nitrogen-based bidentate ligand, 6-(quinolin-8-yl)-6,7-dihydro-5H-dibenzo[c,e]azepine as Ligand, L was synthesized and used for the preparation of a series of mononuclear Ni(II) and Zn(II) complexes, [ML(X)2] which differ only by the halide ion attached to the respective metal center. All complexes of this series showed tetrahedral geometry regardless of the halide ion and metal center (Ni/Zn). The complexes were characterized by different spectroscopic techniques. The triflate (OTf) complexes of Fe(II) and Cu(II) were also synthesized to evaluate their ORR activity. All the complexes were investigated for their electrocatalytic activity in oxygen reduction reaction (ORR) in which complex 1, [NiL(Cl)2] showed the highest activity with an onset potential of 0.75 V. The remaining complexes also showed significant ORR performance with onset potentials close to that of complex 1.
• Ganesan, Vellaichamy,Junaid, Qazi Mohammad,Sabiah, Shahulhameed,Singh, Devesh Kumar
• supporting information

  (2022/01/31)
• 

• Tailoring the Electronic Structure of an Atomically Dispersed Zinc Electrocatalyst: Coordination Environment Regulation for High Selectivity Oxygen Reduction
• Accurately regulating the selectivity of the oxygen reduction reaction (ORR) is crucial to renewable energy storage and utilization, but challenging. A flexible alteration of ORR pathways on atomically dispersed Zn sites towards high selectivity ORR can be achieved by tailoring the coordination environment of the catalytic centers. The atomically dispersed Zn catalysts with unique O- and C-coordination structure (ZnO3C) or N-coordination structure (ZnN4) can be prepared by varying the functional groups of corresponding MOF precursors. The coordination environment of as-prepared atomically dispersed Zn catalysts was confirmed by X-ray absorption fine structure (XAFs). Notably, the ZnN4 catalyst processes a 4 e? ORR pathway to generate H2O. However, controllably tailoring the coordination environment of atomically dispersed Zn sites, ZnO3C catalyst processes a 2 e? ORR pathway to generate H2O2 with a near zero overpotential and high selectivity in 0.1 M KOH. Calculations reveal that decreased electron density around Zn in ZnO3C lowers the d-band center of Zn, thus changing the intermediate adsorption and contributing to the high selectivity towards 2 e? ORR.
• Jia, Yaling,Li, Guangqin,Liu, Qinghua,Liu, Qinglin,Sun, Yamei,Xian, Jiahui,Xue, Ziqian,Yang, Jun,Yao, Daoxin,Zhang, Xiuxiu,Zhong, Yicheng
• supporting information

  (2021/12/09)
• 

• An Iron(III) Superoxide Corrole from Iron(II) and Dioxygen
• A new structurally characterized ferrous corrole [FeII(ttppc)]? (1) binds one equivalent of dioxygen to form [FeIII(O2?.)(ttppc)]? (2). This complex exhibits a 16/18O2-isotope sensitive ν(O-O) stretch at 1128 cm?1 concomitantly with a single ν(Fe-O2) at 555 cm?1, indicating it is an η1-superoxo (“end-on”) iron(III) complex. Complex 2 is the first well characterized Fe-O2 corrole, and mediates the following biologically relevant oxidation reactions: dioxygenation of an indole derivative, and H-atom abstraction from an activated O?H bond.
• Albert, Therese,Goldberg, David P.,Mo?nne-Loccoz, Pierre,Sacramento, Jireh Joy D.,Siegler, Maxime

• (2021/12/03)
• 

• Cobalt ion redox and conductive polymers boosted the photocatalytic activity of the graphite carbon nitride-Co3O4Z-scheme heterostructure
• The enhanced photocatalytic hydrogen evolution performance of g-C3N4-Co3O4 2D-1D Z-scheme heterojunctions was achieved by employing the cobalt ion redox and conductive polymers (polyaniline, PANi) for the first time. Specifically, a Co3O4 1D nanobelt acting as the Z-scheme heterostructure component could promote the separation of photo-excited charge carriers and increased the redox capacity, and the conductive PANi brought about the boosted transport efficiency of the charge carriers. Notably, cobalt ions were adopted as the intermediate of the electron transfer between two components for boosting the carrier transport and utilization efficiency. Consequently, the Co3O4 nanobelt, PANi and cobalt ions exhibited a synergistic effect on facilitating the photocatalytic HER performance of the g-C3N4-based heterostructure, and the optimal ternary heterostructure (g-C3N4-PANi-Co3O4) exhibited a photocatalytic H2-evolution rate of 4.61 μmol h-1 under visible light, which further increased to 9.95 μmol h-1 by adding Co2+ solution owing to the further facilitated transport of charge carriers through the redox reaction of cobalt ions. Moreover, even in the absence of sacrificial agents, this Z-scheme system exhibited a photocatalytic hydrogen production activity of 3.35 μmol h-1 in the Co2+ aqueous solution under UV-visible light.
• Li, Tao,Cui, Jiandong,Lin, Yezhan,Liu, Kecheng,Li, Rui,Wang, Bo,Xie, Haiquan,Li, Kui
• supporting information

  p. 162 - 168

  (2021/01/11)
• 

• Ultrathin Porous Carbon Nitride Bundles with an Adjustable Energy Band Structure toward Simultaneous Solar Photocatalytic Water Splitting and Selective Phenylcarbinol Oxidation
• Actiniae-like carbon nitride (ACN) bundles were synthesized by the pyrolysis of an asymmetric supramolecular precursor prepared from L-arginine (L-Arg) and melamine. ACN has adjustable band gaps (2.25 eV–2.75 eV) and hollow microtubes with ultrathin pore
• Wu, Baogang,Zhang, Liping,Jiang, Baojiang,Li, Qi,Tian, Chungui,Xie, Ying,Li, Weizuo,Fu, Honggang
• supporting information

  p. 4815 - 4822

  (2021/01/20)
• 

• Single-atom nickel terminating sp2and sp3nitride in polymeric carbon nitride for visible-light photocatalytic overall water splitting
• Polymeric carbon nitride (PCN) has been widely used as a metal-free photocatalyst for solar hydrogen generation from water. However, rapid charge carrier recombination and sluggish water catalysis kinetics have greatly limited its photocatalytic performance for overall water splitting. Herein, a single-atom Ni terminating agent was introduced to coordinate with the heptazine units of PCN to create new hybrid orbitals. Both theoretical calculation and experimental evidence revealed that the new hybrid orbitals synergistically broadened visible light absorptionviaa metal-to-ligand charge transfer (MLCT) process, and accelerated the separation and transfer of photoexcited electrons and holes. The obtained single-atom Ni terminated PCN (PCNNi), without an additional cocatalyst loading, realized efficient photocatalytic overall water splitting into easily-separated gas-product H2and liquid-product H2O2under visible light, with evolution rates reaching 26.6 and 24.0 μmol g?1h?1, respectively. It was indicated that single-atom Ni and the neighboring C atom served as water oxidation and reduction active sites, respectively, for overall water splittingviaa two-electron reaction pathway.
• Li, Yanrui,Wang, Yiqing,Dong, Chung-Li,Huang, Yu-Cheng,Chen, Jie,Zhang, Zhen,Meng, Fanqi,Zhang, Qinghua,Huangfu, Yiliang,Zhao, Daming,Gu, Lin,Shen, Shaohua

• p. 3633 - 3643

  (2021/03/24)
• 

• Overall Oxygen Electrocatalysis on Nitrogen-Modified Carbon Catalysts: Identification of Active Sites and In Situ Observation of Reactive Intermediates
• The recent mechanistic understanding of active sites, adsorbed intermediate products, and rate-determining steps (RDS) of nitrogen (N)-modified carbon catalysts in electrocatalytic oxygen reduction (ORR) and oxygen evolution reaction (OER) are still rife with controversy because of the inevitable coexistence of diverse N configurations and the technical limitations for the observation of formed intermediates. Herein, seven kinds of aromatic molecules with designated single N species are used as model structures to investigate the explicit role of each common N group in both ORR and OER. Specifically, dynamic evolution of active sites and key adsorbed intermediate products including O2 (ads), superoxide anion O2?*, and OOH* are monitored with in situ spectroscopy. We propose that the formation of *OOH species from O2?* (O2?*+H2O→OOH*+OH?) is a possible RDS during the ORR process, whereas the generation of O2 from OOH* species is the most likely RDS during the OER process.
• Lin, Yangming,Liu, Zigeng,Yu, Linhui,Zhang, Gui-Rong,Tan, Hao,Wu, Kuang-Hsu,Song, Feihong,Mechler, Anna K.,Schleker, P. Philipp M.,Lu, Qing,Zhang, Bingsen,Heumann, Saskia
• supporting information

  p. 3299 - 3306

  (2020/12/11)
• 

• Bimetallic zeolite-imidazole framework-based heterostructure with enhanced photocatalytic hydrogen production activity
• Bimetallic zeolite-imidazole frameworks with controllable flat band position, band gap and hydrogen evolution reaction characteristics were adopted as a photocatalytic hydrogen production catalyst. Furthermore, the g-C3N4-MoS22D-2D surface heterostructure was introduced to the ZnM-ZIF to facilitate the separation as well as utilization efficiency of the photo-exited charge carriers in the ZnM-ZIFs. On the other hand, the ZnM-ZIFs not only inhibited the aggregation of the g-C3N4-MoS2heterostructure, but also improved the separation and transport efficiency of charge carriers in g-C3N4-MoS2. Consequently, the optimal g-C3N4-MoS2-ZnNi-ZIF exhibited an extraordinary photocatalytic hydrogen evolution activity 214.4, 37.5, and 3.7 times larger than that of the pristine g-C3N4, g-C3N4-ZnNi-ZIF and g-C3N4-MoS2, respectively, and exhibited a H2-evolution performance of 77.8 μmol h?1g?1under UV-Vis light irradiation coupled with oxidation of H2O into H2O2. This work will furnish a new MOF candidate for photocatalysis and provide insight into better utilization of porous MOF-based heterostructures for hydrogen production from pure water.
• Arif, Nayab,Lin, Ye-Zhan,Wang, Kai,Dou, Yi-Chuan,Zhang, Yu,Li, Kui,Liu, Shiquan,Liu, Fu-Tian

• p. 9048 - 9056

  (2021/03/16)
• 

• Isolated single iron atoms anchored on a N, S-codoped hierarchically ordered porous carbon framework for highly efficient oxygen reduction
• Atomically dispersed metal catalysts are promising candidates for the oxygen reduction reaction (ORR) and for achieving efficient energy conversion. However, rational design of single atom catalysts (SACs) with high-efficiency ORR catalytic activity and superior stability is still crucial yet challenging. Herein, anin situgas-foaming methodology is presented for constructing single Fe atoms dispersed on a N, S-codoped (FeSA/NSC) hierarchically ordered porous carbon (HOPC) frameworkviaone-step pyrolysis of dopamine (DA)/Fe3+complexes and thiourea in SBA-15 channels. HOPC structures (facilitating active site access and mass transfer) and optimized FeN4S2catalytic centers make FeSA/NSC exhibit high ORR activity with a half-wave potential (E1/2) of 0.91 V, fuel selectivity and long-term stability (3 mV negative shift after 5000 potential cycles) in 0.1 M KOH. It even shows comparable ORR catalytic activity (E1/2= 0.78 V) to the Pt/C catalyst in acidic electrolytes. As the air electrode in zinc-air batteries, FeSA/NSC demonstrates superior power density, long-term discharge stability and specific capacity to the commercial Pt/C catalyst. Thus, FeSA/NSC is a promising non-platinum-group metal ORR catalyst for the ORR and application in zinc-air batteries.
• Liu, Xinghuan,Zhai, Xingwu,Sheng, Wenbo,Tu, Juan,Zhao, Zeyu,Shi, Yulin,Xu, Caixia,Ge, Guixian,Jia, Xin

• p. 10110 - 10119

  (2021/05/04)
• 

• Highly efficient photosynthesis of hydrogen peroxide in ambient conditions
• Photosynthesis of hydrogen peroxide (H2O2) in ambient conditions remains neither cost effective nor environmentally friendly enough because of the rapid charge recombination. Here, a photocatalytic rate of as high as 114 μmol·g?1·h?1 for the production of H2O2 in pure water and open air is achieved by using a Z-scheme heterojunction, which outperforms almost all reported photocatalysts under the same conditions. An extensive study at the atomic level demonstrates that Z-scheme electron transfer is realized by improving the photoresponse of the oxidation semiconductor under visible light, when the difference between the Fermi levels of the two constituent semiconductors is not sufficiently large. Moreover, it is verified that a type II electron transfer pathway can be converted to the desired Z-scheme pathway by tuning the excitation wavelengths. This study demonstrates a feasible strategy for developing efficient Z-scheme photocatalysts by regulating photoresponses.
• Ye, Yu-Xin,Pan, Jinhui,Xie, Fangyan,Gong, Li,Huang, Siming,Ke, Zhuofeng,Zhu, Fang,Xu, Jianqiao,Ouyang, Gangfeng

• (2021/04/30)
• 

• Pharmaceutical Excipients Enhance Iron-Dependent Photo-Degradation in Pharmaceutical Buffers by near UV and Visible Light: Tyrosine Modification by Reactions of the Antioxidant Methionine in Citrate Buffer
• Purpose: To evaluate the effect of excipients, including sugars and amino acids, on photo-degradation reactions in pharmaceutical buffers induced by near UV and visible light. Methods: Solutions of citrate or acetate buffers, containing 1 or 50?μM Fe3+, the model peptides methionine enkephalin (MEn), leucine enkephalin (LEn) or proctolin peptide (ProP), in the presence of commonly used amino acids or sugars, were photo-irradiated with near UV or visible light. The oxidation products were analyzed by reverse-phase HPLC and HPLC-MS/MS. Results: The sugars mannitol, sucrose and trehalose, and the amino acids Arg, Lys, and His significantly promote the oxidation of peptide Met to peptide Met sulfoxide. These excipients do not increase the yields of hydrogen peroxide, suggesting that other oxidants such as peroxyl radicals are responsible for the oxidation of peptide Met. The addition of free Met reduces the oxidation of peptide Met, but, in citrate buffer, causes the addition of Met oxidation products to Tyr residues of the target peptides. Conclusions: Commonly used excipients enhance the light-induced oxidation of amino acids in model peptides.
• Subelzu, Natalia,Sch?neich, Christian

• p. 915 - 930

  (2021/05/05)
• 

• Sustainable plasma-catalytic bubbles for hydrogen peroxide synthesis
• Hydrogen peroxide (H2O2) is a green oxidant widely used in various fields, from water treatment to rocket propellant. Currently, H2O2is predominantly manufacturedviathe anthraquinone process, which requires large infrastructure investments and high energy consumption. In this study, an argon plasma-catalytic bubble process was designed to generate underwater plasma bubbles for efficient delivery of reactive species for H2O2synthesis, using only water as a reactant and solar radiation as the renewable energy source. The process demonstrates unprecedented energy efficiency by employing a plasma-bubble catalytic reactor capable of operation in two discharge modes,i.e., glow and spark discharges, and using dual reactors within a single AC-circuit to mitigate energy losses around the ground electrode. The results suggest that the principal route of H2O2generation is from the combination of dissolved ˙OH radicals at the plasma-liquid interface (PLI) of the forming bubbles. The dissolution of H2O2formed in the gas phase also contributes to aqueous H2O2generation, especially when employing humid argon. By employing a secondary reactor to utilise the lost energy around the low-voltage electrode and integrating a strongly interfacial-coupled 2D-TiO2/2D-g-C3N4photocatalyst in the glow discharge area, the achieved H2O2production rate and energy efficiency of the system are 164.6 mg h?1and 9.0 g kW h?1, respectively. This study provides new insights for sustainable and decentralised H2O2production, and the proposed strategy can be further developed as a stand-alone or auxiliary technology in green and sustainable chemistry.
• Cullen, Patrick J.,Fang, Zhi,Mai-Prochnow, Anne,Mei, Danhua,Ostrikov, Kostya,Wang, Sen,Weerasinghe, Janith,Zhang, Tianqi,Zhou, Renwu,Zhou, Rusen
• supporting information

  p. 2977 - 2985

  (2021/05/05)
• 

• Role of an Inorganic Phosphate in the Photogeneration of Hydrogen Peroxide in Aqueous Solutions of Adenine Derivatives at 77 K
• Abstract: A comparative study is performed of the effect an inorganic phosphate (Pi) has on the formation of hydrogen peroxide in aqueous solutions of 2 × 10?4 M adenine derivatives (AX), such as adenine, adenosine, and adenosine-5'-diphosphate, irradiated at 77 K by near-UV in the wavelength range λ = 260–400 and 290–460 nm. It is found that the yield of H2O2 in irradiated samples grows upon adding 5 × 10?4 M Pi. The yield of H2O2 is normally increased in the presence of NaCl, while a tenfold increase in [Pi] results in only a moderate rise in [H2O2]. It is shown that the effect irradiation has on the yield of H2O2 depends on both AX and the [NaCl] and [Pi] ratio. The obtained data are compared to the results from measuring the EPR spectra of irradiated solutions before defrosting. Possible mechanisms of photoinitiated processes of H2O2 formation in the studied systems are discussed.
• Brzhevskaya, O. N.,Degtyarev, E. N.,Lander, A. V.,Lobanov, A. V.,Lozinova, T. A.

• p. 1591 - 1600

  (2021/08/24)
• 

• H2O2-Induced Oxidative Dissolution of UO2 in Saline Solutions
• H2O2 is one of the oxidants responsible for driving the process of radiation-induced dissolution of spent nuclear fuel in geological repositories for spent nuclear fuel. As the groundwater composition will vary depending on geographi
• El Jamal, Ghada,Li, Junyi,Jonsson, Mats

• p. 4175 - 4182

  (2021/10/14)
• 

• Efficient electrochemical water oxidation to hydrogen peroxide over intrinsic carbon defect-rich carbon nanofibers
• The two-electron water oxidation reaction (2e-WOR) provides a promising route to produce hydrogen peroxide (H2O2) from water; but it is currently hampered by low H2O2 partial current. Here, intrinsic carbon defect-rich carbon nanofibers are demonstrated to be highly effective for electrochemical 2e-water oxidation. A H2O2 current density of 72.6 mA cm-2 is achieved at 2.9 V vs. RHE which is among the highest values reported for the 2e-WOR. XPS and NEXAFS studies indicate that pentagonal and octagonal ring defects are dominant in the optimal sample. A combination of DFT calculations and a methanol competitive oxidation experiment reveals that ring defects effectively reduce the adsorption strength of OH?, which ultimately promotes the 2e-WOR for valuable H2O2 production. Our study makes a helpful attempt in exploring carbon-based materials for efficient 2e-WOR electrocatalysts. This journal is
• Chen, Xin,Cui, Jiwei,Liu, Lequan,Ning, Shangbo,Sun, Yanhui,Wang, Defa,Yang, Zhongshan,Ye, Jinhua,Zhou, Wei

• p. 23994 - 24001

  (2021/11/16)
• 

• Visible-Light-Driven Sonophotocatalysis for the Rapid Reduction of Aqueous Cr(VI) Based on Zirconium-Porphyrin Metal-Organic Frameworks with csq Topology
• Photochemical treatment of highly toxic Cr(VI) is a desirable and ecofriendly method to protect the environment and human beings. In this study, a MOF-based sonophotocatalytic system is established, in which visible-light-driven sonophotocatalytic reduction of toxic Cr(VI) to Cr(III) in water is investigated using zirconium-porphyrin metal-organic frameworks (MOFs) structured as PCN-222(M) [M = H2, Zn(II), Fe(III), Co(II)]. In the view of the synergistic effect of sonochemistry and photocatalysis, PCN-222(M) exhibited enhanced activities for Cr(VI) reduction compared with the photocatalytic process. Kinetic studies showed that apparent reaction rate constants in the sonophotocatalytic system of PCN-222(M) are 1.5-3.3 times higher than those in photocatalysis. Fluorescence and UV-vis absorption spectra measurements demonstrate that the sonophotocatalytic process promotes the transfer of photoinduced electrons from PCN-222(M) to Cr(VI), thus enhancing the catalytic performance. The innovative combination of porous MOFs and sonophotocatalytic technology might become a feasible strategy to improve the existing MOF-based photocatalytic systems.
• Chen, Dashu,Liu, Wenhao,Guo, Zhifen,Jin, Zhi,Li, Bin,Xing, Hongzhu
• supporting information

  p. 18133 - 18140

  (2021/11/23)
• 

• Photo-charge regulation of metal-free photocatalyst by carbon dots for efficient and stable hydrogen peroxide production
• Solar-driven water splitting for hydrogen peroxide (H2O2) production is a sustainable and ultra-clean method. It is difficult for a single-component photocatalyst to meet all the requirements for efficient and stable photoproduction of H2O2. Meanwhile, for multiple-component catalysts, a huge and urgent challenge is to adjust the photo-charge between the multiple components and interfaces of catalysts. Herein, we report a metal-free photocatalyst CN1.8/ICT/CDs composed of CN1.8, organic small molecules (ICT) and N, S-doped carbon dots (CDs) to produce H2O2 efficiently and stably through a dual-channel process. In this catalyst system, CDs are first reported as the active site of water oxidation reaction (WOR) and ICT as the active site of oxygen reduction reaction (ORR), with greatly improved efficiency of the use of photo-charge, and the poisoning of CN1.8/ICT/CDs by H2O2 was prevented. In situ transient photovoltage measurements (TPV) further revealed the photo-charge regulation function of CDs in this multiple-component metal-free photocatalyst. As a result, the CN1.8/ICT/CDs catalyst exhibits a prominent H2O2 production rate of 2202.81 μmol h-1 g-1 (λ ≥ 420 nm), which represents the most efficient H2O2 production rate from a metal-free photocatalyst in air atmosphere without sacrificial agents. This work also provides a valid TPV-based method for a deep understanding of complex photocatalytic systems.
• Han, Yidong,Huang, Hui,Kang, Zhenhui,Li, Yi,Liu, Yang,Wu, Jie,Zhao, Yu
• supporting information

  p. 25453 - 25462

  (2021/12/04)
• 

• Pendent Relay Enhances H2O2Selectivity during Dioxygen Reduction Mediated by Bipyridine-Based Co-N2O2Complexes
• Generally, cobalt-N2O2 complexes show selectivity for hydrogen peroxide during electrochemical dioxygen (O2) reduction. We recently reported a Co(III)-N2O2 complex with a 2,2′-bipyridine-based ligand backbone which showed alternative selectivity: H2O was observed as the primary reduction product from O2 (71 ± 5%) with decamethylferrocene as a chemical reductant and acetic acid as a proton donor in methanol solution. We hypothesized that the key selectivity difference in this case arises in part from increased favorability of protonation at the distal O position of the key intermediate Co(III)-hydroperoxide species. To interrogate this hypothesis, we have prepared a new Co(III) compound that contains pendent -OMe groups poised to direct protonation toward the proximal O atom of this hydroperoxo intermediate. Mechanistic studies in acetonitrile (MeCN) solution reveal two regimes are possible in the catalytic response, dependent on added acid strength and the presence of the pendent proton donor relay. In the presence of stronger acids, the activity of the complex containing pendent relays becomes O2 dependent, implying a shift to Co(III)-superoxide protonation as the rate-determining step. Interestingly, the inclusion of the relay results in primarily H2O2 production in MeCN, despite minimal difference between the standard reduction potentials of the three complexes tested. EPR spectroscopic studies indicate the formation of Co(III)-superoxide species in the presence of exogenous base, with greater O2 reactivity observed in the presence of the pendent -OMe groups.
• Cook, Emma N.,Dickie, Diane A.,Dressel, Julia M.,Gan, Yunqiao J.,Machan, Charles W.,Miedaner, Peter R.,Nichols, Asa W.,Shafaat, Hannah S.
• supporting information

  p. 13065 - 13073

  (2021/09/03)
• 

• Metal–Organic-Framework-Supported Molecular Electrocatalysis for the Oxygen Reduction Reaction
• Synthesizing molecule@support hybrids is appealing to improve molecular electrocatalysis. We report herein metal–organic framework (MOF)-supported Co porphyrins for the oxygen reduction reaction (ORR) with improved activity and selectivity. Co porphyrins can be grafted on MOF surfaces through ligand exchange. A variety of porphyrin@MOF hybrids were made using this method. Grafted Co porphyrins showed boosted ORR activity with large (>70 mV) anodic shift of the half-wave potential compared to ungrafted porphyrins. By using active MOFs for peroxide reduction, the number of electrons transferred per O2 increased from 2.65 to 3.70, showing significantly improved selectivity for the 4e ORR. It is demonstrated that H2O2 generated from O2 reduction at Co porphyrins is further reduced at MOF surfaces, leading to improved 4e ORR. As a practical demonstration, these hybrids were used as air electrode catalysts in Zn-air batteries, which exhibited equal performance to that with Pt-based materials.
• Liang, Zuozhong,Guo, Hongbo,Zhou, Guojun,Guo, Kai,Wang, Bin,Lei, Haitao,Zhang, Wei,Zheng, Haoquan,Apfel, Ulf-Peter,Cao, Rui
• supporting information

  p. 8472 - 8476

  (2021/03/08)
• 

• Unifying Concepts in Electro- And Thermocatalysis toward Hydrogen Peroxide Production
• We examine relationships between H2O2 and H2O formation on metal nanoparticles by the electrochemical oxygen reduction reaction (ORR) and the thermochemical direct synthesis of H2O2. The similar mechanisms of such reactions suggest that these catalysts should exhibit similar reaction rates and selectivities at equivalent electrochemical potentials (μˉ i), determined by reactant activities, electrode potential, and temperature. We quantitatively compare the kinetic parameters for 12 nanoparticle catalysts obtained in a thermocatalytic fixed-bed reactor and a ring-disk electrode cell. Koutecky-Levich and Butler-Volmer analyses yield electrochemical rate constants and transfer coefficients, which informed mixed-potential models that treat each nanoparticle as a short-circuited electrochemical cell. These models require that the hydrogen oxidation reaction (HOR) and ORR occur at equal rates to conserve the charge on nanoparticles. These kinetic relationships predict that nanoparticle catalysts operate at potentials that depend on reactant activities (H2, O2), H2O2 selectivity, and rate constants for the HOR and ORR, as confirmed by measurements of the operating potential during the direct synthesis of H2O2. The selectivities and rates of H2O2 formation during thermocatalysis and electrocatalysis correlate across all catalysts when operating at equivalent μˉ i values. This analysis provides quantitative relationships that guide the optimization of H2O2 formation rates and selectivities. Catalysts achieve the greatest H2O2 selectivities when they operate at high H atom coverages, low temperatures, and potentials that maximize electron transfer toward stable OOH? and H2O2? while preventing excessive occupation of O-O antibonding states that lead to H2O formation. These findings guide the design and operation of catalysts that maximize H2O2 formation, and these concepts may inform other liquid-phase chemistries.
• Adams, Jason S.,Flaherty, David W.,Kromer, Matthew L.,Rodríguez-López, Joaquín

• p. 7940 - 7957

  (2021/06/27)
• 

• Atomic-Level Modulation of Electronic Density at Cobalt Single-Atom Sites Derived from Metal–Organic Frameworks: Enhanced Oxygen Reduction Performance
• Demonstrated here is the correlation between atomic configuration induced electronic density of single-atom Co active sites and oxygen reduction reaction (ORR) performance by combining density-functional theory (DFT) calculations and electrochemical analysis. Guided by DFT calculations, a MOF-derived Co single-atom catalyst with the optimal Co1-N3PS active moiety incorporated in a hollow carbon polyhedron (Co1-N3PS/HC) was designed and synthesized. Co1-N3PS/HC exhibits outstanding alkaline ORR activity with a half-wave potential of 0.920 V and superior ORR kinetics with record-level kinetic current density and an ultralow Tafel slope of 31 mV dec?1, exceeding that of Pt/C and almost all non-precious ORR electrocatalysts. In acidic media the ORR kinetics of Co1-N3PS/HC still surpasses that of Pt/C. This work offers atomic-level insight into the relationship between electronic density of the active site and catalytic properties, promoting rational design of efficient catalysts.
• Chen, Yuanjun,Gao, Rui,Ji, Shufang,Li, Haijing,Tang, Kun,Jiang, Peng,Hu, Haibo,Zhang, Zedong,Hao, Haigang,Qu, Qingyun,Liang, Xiao,Chen, Wenxing,Dong, Juncai,Wang, Dingsheng,Li, Yadong

• p. 3212 - 3221

  (2020/12/14)
• 

• Electrocatalytic hydrogen peroxide production in acidic media enabled by NiS2nanosheets
• The selective two-electron O2reduction reaction (2e?ORR) represents a green, mild, and on-site means of synthesizing H2O2. However, its practical feasibility depends on the development of advanced electrocatalysts, and limited experimental work has been done on non-precious-metal-based materials for the H2O2electrogeneration in acids. Our study here introduces NiS2nanosheets for the first time as an efficient electrocatalyst for the 2e?ORR under acidic conditions. In 0.05 M H2SO4, the NiS2catalyst shows an onset overpotential of ～130 mV and offers high selectivity (H2O2percentage up to 99%). Moreover, the NiS2catalyst attains the largest faradaic efficiency of 98% and the highest H2O2yield rate of 109 ppm h?1at 0.456 V and 0.156 V in the H-cell testing, respectively. The catalytic mechanism is revealed by theoretical calculations.
• Liang, Jie,Wang, Yuanyuan,Liu, Qian,Luo, Yonglan,Li, Tingshuai,Zhao, Haitao,Lu, Siyu,Zhang, Fang,Asiri, Abdullah M.,Liu, Fenggang,Ma, Dongwei,Sun, Xuping

• p. 6117 - 6122

  (2021/03/22)
• 

• Selective Electrocatalytic Reduction of Oxygen to Hydroxyl Radicals via 3-Electron Pathway with FeCo Alloy Encapsulated Carbon Aerogel for Fast and Complete Removing Pollutants
• We reported the selective electrochemical reduction of oxygen (O2) to hydroxyl radicals (.OH) via 3-electron pathway with FeCo alloy encapsulated by carbon aerogel (FeCoC). The graphite shell with exposed -COOH is conducive to the 2-
• Xiao, Fan,Wang, Zining,Fan, Jiaqi,Majima, Tetsuro,Zhao, Hongying,Zhao, Guohua
• supporting information

  p. 10375 - 10383

  (2021/03/24)
• 

• Dynamically Unveiling Metal–Nitrogen Coordination during Thermal Activation to Design High-Efficient Atomically Dispersed CoN4 Active Sites
• We elucidate the structural evolution of CoN4 sites during thermal activation by developing a zeolitic imidazolate framework (ZIF)-8-derived carbon host as an ideal model for Co2+ ion adsorption. Subsequent in situ X-ray absorption spectroscopy analysis can dynamically track the conversion from inactive Co?OH and Co?O species into active CoN4 sites. The critical transition occurs at 700 °C and becomes optimal at 900 °C, generating the highest intrinsic activity and four-electron selectivity for the oxygen reduction reaction (ORR). DFT calculations elucidate that the ORR is kinetically favored by the thermal-induced compressive strain of Co?N bonds in CoN4 active sites formed at 900 °C. Further, we developed a two-step (i.e., Co ion doping and adsorption) Co-N-C catalyst with increased CoN4 site density and optimized porosity for mass transport, and demonstrated its outstanding fuel cell performance and durability.
• He, Yanghua,Shi, Qiurong,Shan, Weitao,Li, Xing,Kropf, A. Jeremy,Wegener, Evan C.,Wright, Joshua,Karakalos, Stavros,Su, Dong,Cullen, David A.,Wang, Guofeng,Myers, Deborah J.,Wu, Gang
• supporting information

  p. 9516 - 9526

  (2021/03/16)
• 

• Strongly Coupled Cobalt Diselenide Monolayers for Selective Electrocatalytic Oxygen Reduction to H2O2 under Acidic Conditions
• Electrosynthesis of hydrogen peroxide (H2O2) in the acidic environment could largely prevent its decomposition to water, but efficient catalysts that constitute entirely earth-abundant elements are lacking. Here we report the experimental demonstration of narrowing the interlayer gap of metallic cobalt diselenide (CoSe2), which creates high-performance catalyst to selectively drive two-electron oxygen reduction toward H2O2 in an acidic electrolyte. The enhancement of the interlayer coupling between CoSe2 atomic layers offers a favorable surface electronic structure that weakens the critical *OOH adsorption, promoting the energetics for H2O2 production. Consequently, on the strongly coupled CoSe2 catalyst, we achieved Faradaic efficiency of 96.7 %, current density of 50.04 milliamperes per square centimeter, and product rate of 30.60 mg cm?2 h?1. Moreover, this catalyst shows no sign of degradation when operating at ?63 milliamperes per square centimeter over 100 hours.
• Duan, Yu,Gao, Fei-Yue,Gao, Min-Rui,Gu, Chao,Hu, Shao-Jin,Niu, Zhuang-Zhuang,Qin, Shuai,Shi, Lei,Su, Xiaozhi,Wu, Rui,Wu, Zhi-Zheng,Yang, Peng-Peng,Zhang, Xiao-Long,Zheng, Xu-Sheng,Zheng, Ya-Rong,Zhu, Jun-Fa

• p. 26922 - 26931

  (2021/10/23)
• 

• Hydrogen peroxide production from oxygen and formic acid by homogeneous Ir-Ni catalyst
• Hydrogen peroxide was directly produced from oxygen and formic acid, catalysed by a hetero-dinuclear Ir-Ni complex with two adjacent sites, at ambient temperature. Synergistic catalysis derived from the hetero-dinuclear Ir and Ni centres was demonstrated by comparing its activity to those of the component mononuclear Ir and Ni complexes. A reaction intermediate of Ir-hydrido was detected by UV-vis, ESI-TOF-MS, and1H NMR spectroscopies. It was revealed that the Ir moiety serves as an active species of Ir-hydrido, reacting with oxygen to afford an Ir-hydroperoxide species through O2insertion, which is the rate-determining step for H2O2production. Meanwhile, the Ni moiety promotes H2O2formation by activating solvents as proton sources. We also found that H2O2production is strongly affected by the solvent dielectric constants (DE); the highest H2O2concentration was obtained in ethylene glycol with a moderate DE. The catalytic mechanism of H2O2production by the Ir-Ni complex was discussed, based on kinetic analysis, isotope labelling experiments, and theoretical DFT calculations.
• Hong, Dachao,Kon, Yoshihiro,Ohgomori, Yuji,Shimoyama, Yoshihiro
• supporting information

  p. 9410 - 9416

  (2021/07/17)
• 

• Maximizing the Catalytic Performance of Pd@AuxPd1?x Nanocubes in H2O2 Production by Reducing Shell Thickness to Increase Compositional Stability
• We report a simple route based upon seed-mediated growth to the synthesis of Pd@AuxPd1?x (0.8≤x≤1) core–shell nanocubes. Benefiting from the well-defined {100} facets and an optimal Au/Pd ratio for the surface, the nanocubes bearing a shell made of Au0.95Pd0.05 work as an efficient electrocatalyst toward H2O2 production, with high selectivity of 93–100 % in the low-overpotential region of 0.4–0.7 V. When the Au0.95Pd0.05 alloy is confined to a shell of only three atomic layers in thickness, the electrocatalyst is able to maintain its surface structure and elemental composition, endowing continuous and stable production of H2O2 during oxygen reduction at a high rate of 1.62 mol g(Pd+Au)?1 h?1. This work demonstrates a versatile route to the rational development of active and durable electrocatalysts based upon alloy nanocrystals.
• Chen, Ruhui,Chen, Zitao,Chi, Miaofang,Lyu, Zhiheng,Shao, Minhua,Shi, Yifeng,Xia, Younan,Xie, Minghao,Yao, Yao,Zhang, Yu,Zhu, Shangqian
• supporting information

  p. 19643 - 19647

  (2021/08/06)
• 

• Dynamic Control of Sacrificial Bond Transformation in the Fe?N?C Single-Atom Catalyst for Molecular Oxygen Reduction
• Atomically dispersed metal-nitrogen sites show great prospect for the oxygen reduction reaction (ORR), whereas the unsatisfactory adsorption-desorption behaviors of oxygenated intermediates on the metal centers impede improvement of the ORR performance. We propose a new conceptual strategy of introducing sacrificial bonds to remold the local coordination of Fe?Nx sites, via controlling the dynamic transformation of the Fe?S bonds in the Fe?N?C single-atom catalyst. Spectroscopic and theoretical results reveal that the selective cleavage of the sacrificial Fe?S bonds induces the incorporation of the electron-withdrawing oxidized sulfur on the Fe centers. The newly functionalized moieties endow the catalyst with superior ORR activity and remarkable stability, owing to the reduced electron localization around the Fe centers facilitating the desorption of ORR intermediates. These findings provide a unique perspective for precisely controlling the coordination structure of single-atom materials to optimize their activity.
• Li, Yuchan,Ruan, Yuefei,Yu, Li
• supporting information

  p. 25296 - 25301

  (2021/10/25)
• 

• Resolving the Dilemma of Fe-N-C Catalysts by the Selective Synthesis of Tetrapyrrolic Active Sites via an Imprinting Strategy
• Combining the abundance and inexpensiveness of their constituent elements with their atomic dispersion, atomically dispersed Fe-N-C catalysts represent the most promising alternative to precious-metal-based materials in proton exchange membrane (PEM) fuel cells. Due to the high temperatures involved in their synthesis and the sensitivity of Fe ions toward carbothermal reduction, current synthetic methods are intrinsically limited in type and amount of the desired, catalytically active Fe-N4 sites, and high active site densities have been out of reach (dilemma of Fe-N-C catalysts). We herein identify a paradigm change in the synthesis of Fe-N-C catalysts arising from the developments of other M-N-C single-atom catalysts. Supported by DFT calculations we propose fundamental principles for the synthesis of M-N-C materials. We further exploit the proposed principles in a novel synthetic strategy to surpass the dilemma of Fe-N-C catalysts. The selective formation of tetrapyrrolic Zn-N4 sites in a tailor-made Zn-N-C material is utilized as an active-site imprint for the preparation of a corresponding Fe-N-C catalyst. By successive low- and high-temperature ion exchange reactions, we obtain a phase-pure Fe-N-C catalyst, with a high loading of atomically dispersed Fe (>3 wt %). Moreover, the catalyst is entirely composed of tetrapyrrolic Fe-N4 sites. The density of tetrapyrrolic Fe-N4 sites is more than six times as high as for previously reported tetrapyrrolic single-site Fe-N-C fuel cell catalysts.
• Ar?on, Iztok,Fellinger, Tim-Patrick,Gaber??ek, Miran,Koyutürk, Burak,Li, Yan-Sheng,Low, Jian Liang,Menga, Davide,Paulus, Beate,Ruiz-Zepeda, Francisco,Wagner, Friedrich
• supporting information

  p. 18010 - 18019

  (2021/11/12)
• 

• KNO3-Assisted incorporation of K dopants and N defects into g-C3N4with enhanced visible light driven photocatalytic H2O2production
• Doping with heteroatoms and introducing defects are efficient protocols to enhance the photocatalytic performance of graphitic carbon nitride (g-C3N4) for H2O2 production. Herein, a facile one-pot KNO3-assisted thermal polymerization of thiourea and urea was reported for the modification of g-C3N4 with K dopants and N defects (denoted as M-CN-K-1). As a visible light photocatalyst with isopropanol as an electron donor, the obtained M-CN-K-1 sample exhibited an excellent H2O2 production activity of 2.92 mmol g-1 g-C3N4 h-1, which was 15.6, 5.8 and 2.2 times that of pristine g-C3N4 samples derived from urea, thiourea, and a mixture of thiourea and urea, respectively. The outstanding performance of the KNO3-modified g-C3N4 is attributed to the controllable introduction of cyano groups on the opened s-triazine heterocycle and K insertion into the g-C3N4 layers, which are conducive to regulating the morphology, electronic structure, and electron withdrawing and transfer capability. The KNO3-modified g-C3N4 possesses a lamellar structure with a high surface area, smaller energy gap for broadened visible light absorption, more negative conduction band position with stronger reduction ability, suppressed recombination of electron-hole pairs, and enhanced electron transfer, which exert a synergistic effect on the photocatalytic H2O2 production. The H2O2 formation in M-CN-K-1 undergoes the pathway of two-step one-electron indirect O2 reduction (O2 → O-2→ H2O2). This study provides a facile and promising strategy for the modification of g-C3N4 to boost the photocatalytic H2O2 production activity. This journal is
• Qian, Xiaorong,Yang, Haihua,Zhang, Li,Zhang, Na,Zhou, Minjie

• p. 22591 - 22601

  (2021/12/24)
• 

• Rapid Controllable Synthesis of Atomically Dispersed Co on Carbon under High Voltage within One Minute
• Developing a rapid and low cost approach to access atomically dispersed metal catalysts (ADMCs) supported by carbon is important but still challenging. Here, an electric flash strategy using high voltage for the rapid fabrication of carbon-supported ADMCs within 1?min is reported. Continuous plasma arc results in nitrogen-doped carbon ultrathin nanosheets, while an intermittent spark pulse constructs carbon hollow nanospheres via blasting effect, and both structures are decorated with atomically dispersed cobalt. The latter catalyst shows a half-wave potential of 0.887?V versus RHE (47?mV higher than commercial Pt/C) in an oxygen reduction reaction (ORR) in alkaline media. The authors’ work paves the way to rapid synthesis of carbon-supported ADMCs at both low cost and mass production.
• Du, Junyi,Wu, Geng,Liang, Kuang,Yang, Jia,Zhang, Yida,Lin, Yue,Zheng, Xusheng,Yu, Zhen-Qiang,Wu, Yuen,Hong, Xun

• (2021/01/25)
• 

• Phase control of ultrafine FeSe nanocrystals in a N-doped carbon matrix for highly efficient and stable oxygen reduction reaction
• Transition metal chalcogenides have been known as cost-effective and energy-efficient electrocatalysts for the oxygen reduction reaction (ORR). Crystal phase control is vital for tailoring their ORR performances. Herein, hexagonal (h-FeSe) and tetragonal FeSe (t-FeSe) ultrafine nanocrystals are jointly encapsulated in a N-doped carbon matrix without agglomeration. Their phase evolution at different pyrolysis temperatures is explicitly elucidated. The resultant material that contains the highest amount of h-FeSe nanocrystals exhibits remarkable performances with a positive onset potential of 0.97 V, large limiting current density of 5.4 mA cm?2and low H2O2yield of 6.6%. The material also delivers outstanding catalytic stability and methanol crossover tolerance. Theoretical studies confirm that h-FeSe outperforms t-FeSe in O2adsorption and O-O bond dissociation of *OOH intermediates on active Fe-sites. Thus, h-FeSe is more efficient than t-FeSe towards alkaline ORR. We believe it will provide great inspiration for designing other ORR-efficient transition metal-based electrocatalysts by controlling crystal phases.
• Cao, Yangfei,Huang, Senchuan,Peng, Zhangquan,Yao, Fen,Li, Xiaohui,Liu, Yan,Huang, Haitao,Wu, Mingmei
• supporting information

  p. 3464 - 3471

  (2021/02/26)
• 

• Bottom-up fabrication of triazine-based frameworks as metal-free materials for supercapacitors and oxygen reduction reaction
• Doping porous carbon materials with heteroatoms is an effective approach to enhance the performance in the areas of supercapacitors and the oxygen reduction reaction (ORR). However, most traditional heteroatom-doped metal-free porous carbon materials have random structures and pore distributions with high uncertainty, which is harmful for a deep understanding of supercapacitors and the ORR mechanism. Basing on the molecular design, a series of N, O co-doped porous carbon frameworks (p-PYPZs) has been prepared through the template-free trimerization of cyano groups from our designed and synthesized 2,8-bis(4-isocyanophenyl)-2,3,7,8-tetrahydropyridazino[4,5-g]phthalazine-1,4,6,9-tetraone (PYPZ) monomer and subsequent ionothermal synthesis, which has the advantage that the type, position, content of the heteroatom and the pore structure in the porous carbon material can be regulated. Nitrogen and oxygen atoms introducedviacovalent bond and the hierarchically porous structure endow the material with excellent cycling stability, and 110% capacitance retention after 35?000 cycles in 1 M H2SO4. A symmetric supercapacitor was assembled with the material and shows an energy density of 32 W h kg?1. The material can be applied to the area of oxygen reduction reaction as a metal-free catalyst with an onset potential of 0.85 VversusRHE, indicating the good catalytic ability. The material exhibits excellent methanol crossover resistance and a four-electron pathway mechanism. Results also indicate a positive correlation between the N-Q content and the selectivity of the four-electron pathway. In this paper, the electrochemical properties of materials are regulated at the molecular level, which provides a new idea for further understanding the electrochemical mechanism of energy storage devices.
• Cao, Ronghan,Hu, Fangyuan,Zhang, Tianpeng,Shao, Wenlong,Liu, Siyang,Jian, Xigao

• p. 8384 - 8393

  (2021/03/03)
• 

• Phosphorus modification of cobalt-iron nanoparticles embedded in a nitrogen-doped carbon network for oxygen reduction reaction
• For the electrochemical reduction of oxygen the development of heteroatom-doped carbon-based transition metal catalysts has become a recognized strategy to replace traditional noble metal catalysts. In this work a catalyst consisting of CoFe nanoparticles encapsulated in N-doped carbon-based materials (NC) supported by carbon nanotubes (CNTs),i.e.Fe3Co1@NC/CNTs, was modifiedviatreatment with a phosphate salt to synthesize a P-Fe3Co1@NC/CNTs catalyst. The P-Fe3Co1@NC/CNTs exhibits with 5.29 mA cm?2an enhanced current density which is comparable to a Pt/C catalyst. In addition, a stability and methanol resistance better than the Pt/C catalyst were observed which is ascribed to the carbon encapsulation and the synergies between the two transition metals. Finally, the reaction mechanism of P-doping was studied and discussed. These results provide possible directions for carbon-based catalysts and doping with heteroatoms for the improvement of catalytic activity. Moreover, the zinc-air battery assembled with P-Fe3Co1@NC/CNTs as the air-cathode exhibited a high-power density of 73 mW cm?2, which is comparable to that of Pt/C (71 mW cm?2) and a specific capacity of 763 mA h g?1. The prepared catalyst could potentially serve to take the place of precious metal catalysts in rechargeable Zn-air batteries.
• Zhang, Rui,Wang, Zheng,Zhu, Lin,Lv, Weixin,Wang, Wei

• p. 9450 - 9458

  (2021/03/16)
• 

• Novel cobalt-doped molybdenum oxynitride quantum dot@N-doped carbon nanosheets with abundant oxygen vacancies for long-life rechargeable zinc-air batteries
• Rechargeable zinc-air batteries (ZABs) have emerged as promising alternatives for conventional Li-ion batteries due to their high energy density and low manufacturing cost. However, Pt/C and RuO2-based conventional rechargeable ZABs are mainly constrained by the sluggish kinetics of oxygen reduction/oxygen evolution reactions (ORR/OER), limiting commercialization possibilities. Herein, a new type of oxygen vacancies enriched cobalt-doped molybdenum oxynitride quantum dot-anchored N-doped carbon nanosheets (VO-CMON@NCNs) was demonstrated as an advanced air-cathode for long-life rechargeable ZABs. Such VO-CMON@NCN catalyst has an exceptional ORR performance with a high half-wave potential of 0.857 V and tremendous OER performance with an ultrasmall overpotential of 240 mV at a current density of 10 mA cm?2, outperforming conventional Pt/C and RuO2catalysts. As proof of concept, rechargeable ZABs with an optimal VO-CMON@NCN-800 air-cathode showed an ultrahigh specific capacity of 721.2 mA h gZn?1at a current density of 5 mA cm?2, a tremendous peak power density of 143.7 mW cm?2, and ultralong cycling life of 500 h. These consequences suggest that the oxygen vacancies enriched VO-CMON@NCN can serve as promising bifunctional catalysts for next-generation metal-air batteries and other energy-related applications.
• Nguyen, Thanh Tuan,Balamurugan, Jayaraman,Lau, Kin-Tak,Kim, Nam Hoon,Lee, Joong Hee

• p. 9092 - 9104

  (2021/04/16)
• 

• A simple method for the preparation of a nickel selenide and cobalt selenide mixed catalyst to enhance bifunctional oxygen activity for Zn-air batteries
• Developing a low-cost, simple, and efficient method to prepare excellent bifunctional electrocatalysts toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critical in rechargeable zinc-air batteries. Non-stoichiometric M0.85Se (M = Ni or Co) nanoparticles are synthesized and modified on nitrogen-doped hollow carbon sphere (NHCS). The NHCS loaded Ni0.85Se (Ni0.85Se-NHCS) with rich Ni3+ presents higher OER activity, whereas the NHCS-loaded Co0.85Se (Co0.85Se-NHCS) with abundant Co2+ displays better ORR activity, respectively. When Co0.85Se-NHCS is mixed with Ni0.85Se-NHCS in a mass ratio of 1?:?1, the resulting mixture (Ni0.85Se/Co0.85Se-NHCS-2) shows better ORR and OER dual catalytic functions than a single selenide. Moreover, zinc-air batteries equipped with Ni0.85Se/Co0.85Se-NHCS-2 as the oxygen electrode catalyst exhibit excellent charge and discharge performance as well as improved stability over precious metals. This work has developed a simple and effective method to prepare excellent bifunctional electrocatalysts for ORR and OER, which is beneficial for the practical large-scale application of zinc-air batteries. This journal is
• Huang, Jie-Ping,Li, Nan,Liang, Ying,Pan, Qiu-Ren,Peng, Li-Juan,Xu, Hang-Chang,Yin, Na

• p. 19406 - 19416

  (2021/06/16)
• 

• Bifunctional oxygen electrocatalysis on ultra-thin Co9S8/MnS carbon nanosheets for all-solid-state zinc-air batteries
• The development of high-efficiency and durable bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts as air cathodes is still a challenge in energy storage and conversion. In this work, we report two-dimensional (2D) ultra-thin Co9S8/MnS sulfur/nitrogen co-doped carbon nanosheets (Co9S8/MnS-USNC) with outstanding ORR and OER activities as well as remarkable stability in alkaline media. Benefiting from the accessible functional surface and active sites of the 2D structure and adjustment of the electronic structure by the synergetic effect, Co9S8/MnS-USNC possesses a half-wave potential of 0.90 V for the ORR and a low overpotential of 360 mV for the OER at a current density of 10 mA cm?2. The aqueous zinc-air batteries displayed a maximum power density of 146 mW cm?2and superior durability of 600 hours, and those of all-solid-state zinc-air batteries are 79 mW cm?2and 18 hours respectively. The reaction mechanism of the Co9S8/MnS-USNC catalyst as the air cathode was also verified byin situRaman spectroscopy.
• Deng, Libo,He, Chuanxin,Li, Jiacheng,Li, Wanqing,Li, Yongliang,Mi, Hongwei,Ren, Xiangzhong,Zhang, Qianling
• supporting information

  p. 22635 - 22642

  (2021/10/19)
• 

• MOF Structure Engineering to Synthesize Co-N-C Catalyst with Richer Accessible Active Sites for Enhanced Oxygen Reduction
• Single-atom cobalt-based Co-N-C are promising low-cost electrocatalysts for oxygen reduction reaction (ORR). However, further increasing the single cobalt-based active sites and the ORR activity remain a major challenge. Herein, an acetate (OAc) assisted metal–organic framework (MOF) structure-engineering strategy is developed to synthesize hierarchical accordion-like MOF with higher loading amount and better spatial isolation of Co and much higher yield when compared with widely reported polyhedron MOF. After pyrolysis, the accordion-structured Co-N-C (Co-N-C (A)) is loaded with denser Co-N4 active sites (Co: 2.88?wt%), approximately twice that of Co in the Co-N-C reported. The presence of OAc in MOF also induces the generation of big pores (5–50?nm) for improving the accessibility of active sites and mass transfer during catalytic reactions. Consequently, the Co-N-C (A) catalyst shows an admirable ORR activity with a E1/2 of 0.89?V (40?mV better than Pt/C) in alkaline electrolytes, outstanding durability, and absolute tolerance to methanol in both alkaline and acidic media. The Co-N-C-based Zn-air battery exhibits a high specific capacity (976 mAh g?1Zn),?power density (158?mW cm?2), rate capability, and long-term stability. This work demonstrates a reliable approach to construct single atom doped carbon catalysts with denser accessible active sites through MOF structure engineering.
• Gao, Jiaojiao,Hu, Yixuan,Wang, Yu,Lin, Xiaorong,Hu, Kailong,Lin, Xi,Xie, Guoqiang,Liu, Xingjun,Reddy, Kolan Madhav,Yuan, Qunhui,Qiu, Hua-Jun

• (2021/11/09)
• 

• Effect of Nitro Derivatives of 1,2,4-Triazole on the Radiation-Induced Oxidation of Ethanol
• Abstract: The effect of 1,2,4-triazole and its nitro derivatives on the formation of final molecular products of radiation-induced transformations of oxygen-saturated ethanol has been studied. It has been found that the test compounds are almost not decomposed in the course of radiolysis, whereas they insignificantly decrease or do not affect the radiation-chemical yields of H2O2 and acetaldehyde. The experimental data indicate that the nitro derivatives of 1,2,4-triazole cannot compete with oxygen for α-hydroxyethyl radicals, and they do not interact with oxygen-centered radicals formed in the system. The reaction rate constant of the oxidation of α-hydroxyethyl radicals by the nitro derivatives of 1,2,4-triazole was found to be k ≤ 4.6 × 109 L mol?1 s?1 by calculation using the method of competing reactions.
• Brinkevich,Maliborskii, A. Ya.,Kapusto,Sverdlov,Grigor’ev, Yu. V.,Shadyro

• p. 59 - 64

  (2021/02/27)
• 

• Photocatalytic H2O2 production using Ti3C2 MXene as a non-noble metal cocatalyst
• Photocatalytic H2O2 production by O2 reduction is an environmental-friendly process for solar light conversion to chemical energy. In this work, Ti3C2 MXene was used as a non-noble metal cocatalyst to load on P25 as Ti3C2/TiO2 (TC/TO) photocatalysts for photocatalytic H2O2 synthesis. A H2O2 formation rate (179.7 μmol L?1 h?1) of the optimized 10 %-TC/TO composite was obtained to be over 21 folds as high as that of P25 under UV light. Radical quenching experiments and superoxide radical detection confirmed the superoxide radical as the primary intermediate, suggesting the O2 reduction in two-step single-electron indirect reaction. The higher activity of TC/TO can be attributed to the functions of Ti3C2 MXene in accelerating the separation and transfer of photogenerated electron-hole pairs, suppressing their recombination, and blocking the surface Ti–OOH formation. This work proves the promising roles of Ti3C2 MXene in the photocatalytic reaction and further expands their new applications in photocatalysis.
• Chen, Yiming,Gu, Wenquan,Tan, Li,Ao, Zhimin,An, Taicheng,Wang, Shaobin

• (2021/04/12)
• 

• Growth of narrow-bandgap Cl-doped carbon nitride nanofibers on carbon nitride nanosheets for high-efficiency photocatalytic H2O2generation
• Heterojunction construction has been proved to be an effective way to enhance photocatalysis performance. In this work, Cl-doped carbon nitride nanofibers (Cl-CNF) with broadband light harvesting capacity were in situ grown on carbon nitride nanosheets (CNS) by a facile hydrothermal method to construct a type II heterojunction. Benefiting from the joint effect of the improved charge carriers separation efficiency and a broadened visible light absorption range, the optimal heterostructure of Cl-CNF/CNS exhibits a H2O2 evolution rate of 247.5 μmol g-1 h-1 under visible light irradiation, which is 3.4 and 3.1 times as much as those of Cl-CNF (72.2 μmol g-1 h-1) and CNS (80.2 μmol g-1 h-1), respectively. Particularly, the heterojunction nanostructure displays an apparent quantum efficiency of 23.67% at 420 nm. Photoluminescence spectra and photocurrent measurements both verified the enhanced charge carriers separation ability. Our work provides a green and environmentally friendly strategy for H2O2 production by elaborate nanostructure design.
• Chang, Binbin,Guo, Yanzhen,Ji, Tingshuo,Liu, Huili,Wei, Xuefeng,Yang, Baocheng

• p. 31385 - 31394

  (2021/11/30)
• 

• Hemin-based conjugated effect synthesis of Fe-N/CNT catalysts for enhanced oxygen reduction
• Metal-nitrogen codoped cathode catalysts, such as M-N-C (M = Fe, Co, Mn,etc.) are considered most promising non-platinum group ORR catalysts, and have received widespread attention. However, the problem involving the high oxygen reduction performance and stability of the catalyst remains to be solved. The unique olefin oxidation polymerization and π-π stacking effect induced hemin to be evenly coated on polypyrrole nanotubes (PPy). Subsequent carbonization produces the Fe-NCNT catalyst with a monodispersed, uniform diameter and large inner cavity. The PPy not only serves as a template for the formation of the hemin polymer, but also provides C, N source to further improve the catalytic activity. The material exhibits excellent ORR activity attributed to the promotion of the π-π stacking effect between hemin and PPy, and the abundant active site of Fe-NXderived from hemin. Results show that the Fe-NCNT-800 catalyst with high performance exhibits a maximum onset potential (Eonset= 0.93 V) and half-wave potential (E1/2= 0.79 V). The RRDE measures points out the complete four-electron transfer pathway of the Fe-NCNT-800 catalyst. The Fe-NCNT catalysts have higher durability of a negligible negative shift (10 mV) ofE1/2after a 5000 cycle ADT, and a remarkable methanol tolerance capability that is superior to that of the Pt/C catalyst. The synergy between the PPy-derived N-doped carbon nanotubes and Fe-NXfacilitates oxygen reduction and electron conduction.
• Lu, Yue,Zhang, Han,Liu, Shaojun,Li, Chenglong,Li, Lixiang,An, Baigang,Sun, Chengguo
• supporting information

  p. 6940 - 6949

  (2021/04/22)
• 

• Activity manifestationviaarchitectural manipulation by cubic silica-derived Co3O4electrocatalysts towards bifunctional oxygen electrode performance
• Electrocatalytic water splitting reaction utilizing non-renewable energy resources significantly leads to a sustainable energy infrastructure. Highly efficient bifunctional catalysts for oxygen reduction and oxygen evolution reactions (ORR/OER) are essential for the replacement of platinum, ruthenium and iridium metals. We used four different silica templates to create excellent mesoporous cobalt oxide (Co3O4) electrocatalysts in crystalline form. Various advanced techniques confirm the spinel structure composed of both Co3+and Co2+sites, which lead to an enhanced surface area, mesoporosity, and a rod morphology with a cubic-like network structure. Among these replicas, the Mobil composition of matter (MCM)-48-derived Co3O4(Co3O4-M8) material demonstrates remarkable OER activity with an observed potential of 1.76 V, a Tafel slope of 107 mV dec?1and a lower charge transfer resistance. Such a high performance is observed due to assistance of the Co3+to Co4+transition during the oxygen evolution reaction. The ORR was more active on the Korea advanced institute of science and technology (KIT)-6-derived Co3O4(Co3O4-K6) material, which displayed a more positive onset potential of 0.85 V, a half-wave potential of 0.56 V and a better current density in alkaline medium. In addition, we found that the stabilization of Co2+active sites in the Co3O4-K6 material is the reason for the enhanced oxygen reduction reaction. The observed bifunctional activity (ΔE=EOER@10 mA cm?2? ORR@E1/2) for the Co3O4-K6 catalyst is 1.22 V, which shows significant performance among all the catalysts prepared in this work. Such an earth-abundant mesoporous Co3O4catalyst obtainedviaan environmentally benign process is anticipated to revolutionize electrochemical energy conversion and storage devices.
• Duraisamy, Velu,Selvakumar, Karuppiah,Senthil Kumar, Sakkarapalayam Murugesan
• supporting information

  p. 16913 - 16925

  (2021/09/27)
• 

• Synthesis, characterization, and application of hollow ceramic microsphere based Pd catalyst for hydrogenation of 2-ethylanthraquinone
• Palladium metal has been used extensively in the hydrogenation reactions due to their great affinity towards hydrogen atoms. In the present study, the catalyst preparation attempted with Pd supported Hollow Ceramic Microspheres using wet impregnation method and its use as catalysts is explored in the hydrogenation of 2-ethylanthraquinone studing the effect of the reaction time, temperature, volume of working solution and the catalyst dosages on the conversion of 2-ethylanthraquinone and yield of hydrogen peroxide. The hydrogenation reaction of 2-ethylanthraquinone is the key step in the anthraquinone method for the industrial production of the hydrogen peroxide. The Pd supported catalyst was characterized by XRF, FTIR, and BET to confirm the composition of the prepared catalyst, Pd deposition, and the surface area. The highest catalyst activity was found to be 9.42 ?g/L with the maximum conversion of 96% at 70°C, 0.3 ?MPa. The kinetics of the heterogeneous hydrogenation reaction of 2-ethylanthraquinone with Pd supported on Hollow Ceramic Microspheres as catalyst was also investigated. This paper is in contribution of our earlier publication.
• Ingle, Anjali A.,Shende, Diwakar Z.,Wasewar, Kailas L.

• (2021/11/13)
• 

• Study on the Simple Surface Treatments of N, P Dual-doped Carbon as Metal-free Catalyst for Metal-air Batteries
• N, P dual-doped porous carbon with high specific surface area of ～2000 m2 g?1 was prepared via foaming-carbonization process. It was demonstrated that the simple surface treatment and modification can conveniently further improve the catalytic performance of oxygen reduction reaction (ORR). The results showed that chemisorbed phosphorus can promote the surface treatment of sodium borohydride (NaBH4). The modified novel sites, adsorbing water molecules of a semi-free state, promoted the offensive key steps of H2O molecules in ORR. After post-treatment, the limit current density increased from 5.0 to 6.1 mA cm?2 with a decreased Tafel slope and the onset potential positively shifted. This surface-modified catalyst was applied to Zn-air battery and Al-air battery, and had exhibited good applicability and excellent performances. This work illustrates that the simple post-treatments can conveniently and effectively improve the ORR performance of metal-free carbon catalysts.
• Yu, Heping,Zhang, Hui,Zhang, Zhongyi

• p. 397 - 406

  (2020/12/07)
• 

• Controlling Oxygen Reduction Selectivity through Steric Effects: Electrocatalytic Two-Electron and Four-Electron Oxygen Reduction with Cobalt Porphyrin Atropisomers
• Achieving a selective 2 e? or 4 e? oxygen reduction reaction (ORR) is critical but challenging. Herein, we report controlling ORR selectivity of Co porphyrins by tuning only steric effects. We designed Co porphyrin 1 with meso-phenyls each bearing a bulky ortho-amido group. Due to the resulted steric hinderance, 1 has four atropisomers with similar electronic structures but dissimilar steric effects. Isomers αβαβ and αααα catalyze ORR with n=2.10 and 3.75 (n is the electron number transferred per O2), respectively, but ααββ and αααβ show poor selectivity with n=2.89–3.10. Isomer αβαβ catalyzes 2 e? ORR by preventing a bimolecular O2 activation path, while αααα improves 4 e? ORR selectivity by improving O2 binding at its pocket, a feature confirmed by spectroscopy methods, including O K-edge near-edge X-ray absorption fine structure. This work represents an unparalleled example to improve 2 e? and 4 e? ORR by tuning only steric effects without changing molecular and electronic structures.
• Apfel, Ulf-Peter,Cao, Rui,Guo, Kai,Jin, Xiaotong,Lei, Haitao,Li, Xialiang,Long, Ran,Lv, Bin,Ma, Jun,Wang, Fang,Wang, Yanzhi,Xiong, Yujie,Zhang, Qingxin,Zhang, Wei
• supporting information

  p. 12742 - 12746

  (2021/04/22)
• 

• High-performance AEM unitized regenerative fuel cell using Pt-pyrochlore as bifunctional oxygen electrocatalyst
• The performance of fixed-gas unitized regenerative fuel cells (FG-URFCs) are limited by the bifunctional activity of the oxygen electrocatalyst. It is essential to have a good bifunctional oxygen electrocatalyst which can exhibit high activity for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). In this regard, Pt-Pb2Ru2O7-x is synthesized by depositing Pt on Pb2Ru2O7-x wherein Pt individually exhibits high ORR while Pb2Ru2O7-x shows high OER and moderate ORR activity. Pt-Pb2Ru2O7-x exhibits higher OER (η@10mAcm-2 = 0.25 ± 0.01 V) and ORR (η@-3mAcm-2 = -0.31 ± 0.02 V) activity in comparison to benchmark OER (IrO2, η@10mAcm-2 = 0.35 ± 0.02 V) and ORR (Pt/C, η@-3mAcm-2 = -0.33 ± 0.02 V) electrocatalysts, respectively. Pt-Pb2Ru2O7-x shows a lower bifunctionality index (η@10mAcm-2, OER? η@-3mAcm-2, ORR) of 0.56 V with more symmetric OER–ORR activity profile than both Pt (>1.0 V) and Pb2Ru2O7-x (0.69 V) making it more useful for the AEM (anion exchange membrane) URFC or metal-air battery applications. FG-URFC tested with Pt-Pb2Ru2O7-x and Pt/C as bifunctional oxygen electrocatalyst and bifunctional hydrogen electrocatalyst, respectively, yields a mass-specific current density of 715 ± 11 A/gcat-1 at 1.8 V and 56 ± 2 A/gcat-1 at 0.9 V under electrolyzer mode and fuel-cell mode, respectively. The FG-URFC shows a round-trip efficiency of 75% at 0.1 A/cm?2, underlying improvement in AEM FG-URFC electrocatalyst design.
• Gayen, Pralay,Saha, Sulay,Liu, Xinquan,Sharma, Kritika,Ramani, Vijay K.

• (2021/10/07)
• 

• Insight into facet-dependent photocatalytic H2O2production on BiOCl nanosheets
• Hydrogen peroxide is an important high-energy product widely used in various fields. Highly efficient semiconductor photocatalysts, especially those that can produce H2O2both from water oxidation and O2reduction, are eagerly desired. In this work, BiOCl nanosheets with preferentially exposed (001) and (010) facets were synthesizedviaa simple hydrothermal method. The facet-dependent photocatalytic H2O2generation activities of these BiOCl nanosheets were assessed. The hydrogen peroxide evolution rate of BiOCl(001) is about 2-fold higher than that of BiOCl(010), which is assigned to the higher separation efficiency of photogenerated charge carriers. Interestingly, both the EPR study and active species trapping experiments demonstrate that the generation of H2O2on the BiOCl(001) photocatalyst mostly originates from sequential two step single-electron O2reduction, while there are two pathways for photocatalytic H2O2production on BiOCl(010), from both oxygen reduction and water oxidation. This work offers a new strategy to pursue highly efficient semiconductor photocatalysts with two pathways for H2O2production from both water oxidation and O2reduction.
• Xu, Yating,Fu, Hanping,Zhao, Ling,Jian, Lishan,Liang, Qingshuang,Xiao, Xiufeng

• p. 3335 - 3342

  (2021/02/26)
• 

• Effect of Pd Coordination and Isolation on the Catalytic Reduction of O2to H2O2over PdAu Bimetallic Nanoparticles
• The direct synthesis of hydrogen peroxide (H2 + O2 → H2O2) may enable low-cost H2O2 production and reduce environmental impacts of chemical oxidations. Here, we synthesize a series of Pd1Aux nanoparticles (where 0 ≤ x ≤ 220, μ10 nm) and show that, in pure water solvent, H2O2 selectivity increases with the Au to Pd ratio and approaches 100% for Pd1Au220. Analysis of in situ XAS and ex situ FTIR of adsorbed 12CO and 13CO show that materials with Au to Pd ratios of μ40 and greater expose only monomeric Pd species during catalysis and that the average distance between Pd monomers increases with further dilution. Ab initio quantum chemical simulations and experimental rate measurements indicate that both H2O2 and H2O form by reduction of a common OOH? intermediate by proton-electron transfer steps mediated by water molecules over Pd and Pd1Aux nanoparticles. Measured apparent activation enthalpies and calculated activation barriers for H2O2 and H2O formation both increase as Pd is diluted by Au, even beyond the complete loss of Pd-Pd coordination. These effects impact H2O formation more significantly, indicating preferential destabilization of transition states that cleave O-O bonds reflected by increasing H2O2 selectivities (19% on Pd; 95% on PdAu220) but with only a 3-fold reduction in H2O2 formation rates. The data imply that the transition states for H2O2 and H2O formation pathways differ in their coordination to the metal surface, and such differences in site requirements require that we consider second coordination shells during the design of bimetallic catalysts.
• Ricciardulli, Tomas,Gorthy, Sahithi,Adams, Jason S.,Thompson, Coogan,Karim, Ayman M.,Neurock, Matthew,Flaherty, David W.
• supporting information

  p. 5445 - 5464

  (2021/05/04)
•