7722-84-1Relevant articles and documents
Kinetics and mechanism of O-O bond cleavage in the reaction of [Ru III(edta)(H2O)]- with hydroperoxides in aqueous solution
Chatterjee, Debabrata,Sikdar, Anindita,Patnam, Vidya R.,Theodoridis, Alexander,Van Eldik, Rudi
, p. 3851 - 3856 (2008)
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.
Evidence for urate hydroperoxide as an intermediate in the urate oxidase reaction [14]
Sarma,Tipton
, p. 11252 - 11253 (2000)
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Hierarchically porous few-layer porphyrinic carbon nanosheets formed by a VO: X-templating method for high-efficiency oxygen electroreduction
Kong,Mao,Wang,Lin,Bu,Feng
, p. 7305 - 7312 (2016)
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.
Structural studies on manganese(III) and manganese(IV) complexes of tetrachlorocatechol and the catalytic reduction of dioxygen to hydrogen peroxide
Sheriff, Tippu S.,Carr, Pamela,Coles, Simon J.,Hursthouse, Michael B.,Lesin, Jocelyne,Light, Mark E.
, p. 2494 - 2502 (2004)
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).
Crystalline-Water/Coordination Induced Formation of 3D Highly Porous Heteroatom-Doped Ultrathin Carbon Nanosheet Networks for Oxygen Reduction Reaction
Liu, Tingting,Feng, Shi,Huo, Jia,Li, Qiling,Xie, Chao,Wang, Shuangyin
, p. 4562 - 4568 (2018)
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.
Changes induced by transition metal oxides in Pt nanoparticles unveil the effects of electronic properties on oxygen reduction activity
Ometto, Felipe B.,Carbonio, Emilia A.,Teixeira-Neto, érico,Villullas, Hebe M.
, p. 2075 - 2086 (2019)
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.
Spinel CoMn2O4 nanoparticles supported on a nitrogen and phosphorus dual doped graphene aerogel as efficient electrocatalysts for the oxygen reduction reaction
Guo, Wenhui,Ma, Xiuxiu,Zhang, Xianlei,Zhang, Yaqing,Yu, Dingling,He, Xingquan
, p. 96436 - 96444 (2016)
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.
Room-Temperature Rate Constant for the HO2 + HO2 Reaction at Low Pressures
Takacs, Gerald A.,Howard, Carleton J.
, p. 2110 - 2116 (1984)
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.
Electrocatalytic reduction of dioxygen by Mn(iii): Meso -tetra(N -methylpyridinium-4-yl)porphyrin in universal buffer
Lieske, Lauren E.,Hooe, Shelby L.,Nichols, Asa W.,MacHan, Charles W.
, p. 8633 - 8641 (2019)
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
Key Single-Atom Electrocatalysis in Metal—Organic Framework (MOF)-Derived Bifunctional Catalysts
Zhao, Wanpeng,Wan, Gang,Peng, Chunlei,Sheng, Huaping,Wen, Jianguo,Chen, Hangrong
, p. 3473 - 3479 (2018)
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.
Tris(2,2'-bipyridine)ruthenium(II)-photosensitized Reductions of Methyl Viologen and Molecular Oxygen in a Network of Water-swollen Cation-exchange Resin
Kurimura, Yoshimi,Katsumata, Kimiyo
, p. 2560 - 2563 (1982)
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.
Evidence for the role of colloidal palladium in the catalytic formation of H2O2 from H2 and O2
Dissanayake, Dhammike P.,Lunsford, Jack H.
, p. 173 - 176 (2002)
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.
Electrocatalytic dioxygen reduction on underpotentially deposited Pb on Au(111) studied by an active site blocking strategy
Oh, Ilwhan,Gewirth, Andrew A.,Kwak, Juhyoun
, p. 17 - 22 (2003)
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).
Photoassisted Construction of Holey Defective g-C3N4 Photocatalysts for Efficient Visible-Light-Driven H2O2 Production
Shi, Li,Yang, Liuqing,Zhou, Wei,Liu, Yanyu,Yin, Lisha,Hai, Xiao,Song, Hui,Ye, Jinhua
, (2018)
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.
The screening of metal ion inhibitors for glucose oxidase based on the peroxidase-like activity of nano-Fe3O4
Wu, Yao-Hui,Chu, Lei,Liu, Wen,Jiang, Lun,Chen, Xiao-Yong,Wang, Yong-Hong,Zhao, Yun-Lin
, p. 47309 - 47315 (2017)
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.
Theoretical Modelling and Facile Synthesis of a Highly Active Boron-Doped Palladium Catalyst for the Oxygen Reduction Reaction
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)
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.
Activation of O2 by Organosilicon Reagents Yields Quantitative Amounts of H2O2 or (Me3Si)2O2 for Efficient O-Transfer Reactions
Yamamoto, Keishi,Tanaka, Shinji,Hosoya, Hiromu,Tsurugi, Hayato,Mashima, Kazushi,Copéret, Christophe
, (2018)
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.
Production of Hydrogen Peroxide from Dioxygen and Hydroxylamine or Hydrazine catalysed by Manganese Complexes
Sheriff, Tippu S.
, p. 1051 - 1058 (1992)
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.
Carrington, A.,Symons, M. C. R.
, p. 443 - 460 (1963)
Control of Electrons' Spin Eliminates Hydrogen Peroxide Formation during Water Splitting
Mtangi, Wilbert,Tassinari, Francesco,Vankayala, Kiran,Vargas Jentzsch, Andreas,Adelizzi, Beatrice,Palmans, Anja R. A.,Fontanesi, Claudio,Meijer,Naaman, Ron
, p. 2794 - 2798 (2017)
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.
Oxygen reduction on nanocrystalline ruthenia-local structure effects
Abbott, Daniel F.,Mukerjee, Sanjeev,Petrykin, Valery,Bastl, Zdenk,Halck, Niels Bendtsen,Rossmeisl, Jan,Krtil, Petr
, p. 1235 - 1243 (2015)
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
Photochemistry of Solid Ozone
Sedlacek, Arthur J.,Wight, Charles A.
, p. 509 - 511 (1989)
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.
Hydrogen Abstraction and One-Electron Oxidation in Nickel(II)-Iminodiacetate Complexes
Bhattacharyya, S. N.,Saha, N. C.,Neta, P.
, p. 300 - 305 (1981)
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.
Direct fabrication of tri-metallic PtPdCu tripods with branched exteriors for the oxygen reduction reaction
Wang, Hongjing,Yin, Shuli,Xu, You,Li, Xiaonian,Alshehri, Abdulmohsen Ali,Yamauchi, Yusuke,Xue, Hairong,Kaneti, Yusuf Valentino,Wang, Liang
, p. 8662 - 8668 (2018)
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.
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
Liu, Huiling,Wang, Cheng,Wang, Depeng,Zuo, Xintao
, (2021)
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.
Biphenyl appended non-noble metal complexes as electrocatalysts for the electrochemical oxygen reduction reaction
Ganesan, Vellaichamy,Junaid, Qazi Mohammad,Sabiah, Shahulhameed,Singh, Devesh Kumar
supporting information, (2022/01/31)
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.
An Iron(III) Superoxide Corrole from Iron(II) and Dioxygen
Albert, Therese,Goldberg, David P.,Mo?nne-Loccoz, Pierre,Sacramento, Jireh Joy D.,Siegler, Maxime
, (2021/12/03)
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.
Bimetallic zeolite-imidazole framework-based heterostructure with enhanced photocatalytic hydrogen production activity
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)
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.