32767-18-3Relevant academic research and scientific papers
Oxysulfide photocatalyst for visible-light-driven overall water splitting
Wang, Qian,Nakabayashi, Mamiko,Hisatomi, Takashi,Sun, Song,Akiyama, Seiji,Wang, Zheng,Pan, Zhenhua,Xiao, Xiong,Watanabe, Tomoaki,Yamada, Taro,Shibata, Naoya,Takata, Tsuyoshi,Domen, Kazunari
, p. 827 - 832 (2019)
Oxysulfide semiconductors have narrow bandgaps suitable for water splitting under visible-light irradiation, because the electronegative sulfide ions negatively shift the valence band edges of the corresponding oxides1,2. However, the instability of sulfide ions during the water oxidation is a critical obstacle to simultaneous evolution of hydrogen and oxygen3. Here, we demonstrate the activation and stabilization of Y2Ti2O5S2, with a bandgap of 1.9 eV, as a photocatalyst for overall water splitting. On loading of IrO2 and Rh/Cr2O3 as oxygen and hydrogen evolution co-catalysts, respectively, and fine-tuning of the reaction conditions, simultaneous production of stoichiometric amounts of hydrogen and oxygen was achieved on Y2Ti2O5S2 during a 20 h reaction. The discovery of the overall water splitting capabilities of Y2Ti2O5S2 extends the range of promising materials for solar hydrogen production.
An artificial model of photosynthetic photosystem II: Visible-light-derived O2 production from water by a di-μ-oxo-bridged manganese dimer as an oxygen evolving center
Yagi, Masayuki,Toda, Mayuu,Yamada, Satoshi,Yamazaki, Hirosato
, p. 8594 - 8596 (2010)
Visible-light-derived O2 production was yielded by conjugating water oxidation catalysis by [(OH2)(terpy)Mn(μ-O) 2Mn(terpy)(OH2)]3+ as an oxygen evolving center model and photo-sensitization of [Ru(bpy)3]2+ as a photoexcitation center model at an interlayer of mica.
Photoinduced catalytic reaction by a fluorescent active cryptand containing an anthracene fragment
Hao, Hong-Guo,Zheng, Xiao-Dan,Lu, Tong-Bu
, p. 8148 - 8151 (2010)
Tripping the light fantastic: A fluorescently active cryptand containing an anthracene fragment catalyzes the photoinduced reduction of CuII to CuI with simultaneous oxidation of water to oxygen (see scheme).
3d-4f {CoII3Ln(OR)4} Cubanes as Bio-Inspired Water Oxidation Catalysts
Evangelisti, Fabio,Moré, René,Hodel, Florian,Luber, Sandra,Patzke, Greta Ricarda
, p. 11076 - 11084 (2015)
Although the {CaMn4O5} oxygen evolving complex (OEC) of photosystem II is a major paradigm for water oxidation catalyst (WOC) development, the comprehensive translation of its key features into active molecular WOCs remains challenging. The [CoII3Ln(hmp)4(OAc)5H2O] ({CoII3Ln(OR)4}; Ln = Ho-Yb, hmp = 2-(hydroxymethyl)pyridine) cubane WOC series is introduced as a new springboard to address crucial design parameters, ranging from nuclearity and redox-inactive promoters to operational stability and ligand exchange properties. The {CoII3Ln(OR)4} cubanes promote bioinspired WOC design by newly combining Ln3+ centers as redox-inactive Ca2+ analogues with flexible aqua-/acetate ligands into active and stable WOCs (max. TON/TOF values of 211/9 s-1). Furthermore, they open up the important family of 3d-4f complexes for photocatalytic applications. The stability of the {CoII3Ln(OR)4} WOCs under photocatalytic conditions is demonstrated with a comprehensive analytical strategy including trace metal analyses and solution-based X-ray absorption spectroscopy (XAS) investigations. The productive influence of the Ln3+ centers is linked to favorable ligand mobility, and the experimental trends are substantiated with Born-Oppenheimer molecular dynamics studies. (Chemical Equation Presented).
Oxygen Vacancy Structure Associated Photocatalytic Water Oxidation of BiOCl
Li, Hao,Shang, Jian,Zhu, Huijun,Yang, Zhiping,Ai, Zhihui,Zhang, Lizhi
, p. 8276 - 8285 (2016)
A central issue in understanding photocatalytic water splitting on a stoichiometric or defective nanostructured oxide surface is its adsorption mode and related reactivity. More than just improving the adsorption of water on oxide surfaces, we demonstrate in this work that surface oxygen vacancies (OVs) also offer a possibility of activating water toward thermodynamically enhanced photocatalytic water oxidation, while the water activation state, as reflected by its capability to trap holes, strongly depends on the structures of OVs. Utilizing well-ordered BiOCl single-crystalline surfaces, we reveal that dissociatively adsorbed water on the OV of the (010) surface exhibits higher tendency to be oxidized than the molecularly adsorbed water on the OV of the (001) surface. Analysis of the geometric atom arrangement shows that the OV of the BiOCl (010) surface can facilitate barrierless O-H bond breaking in the first proton removal reaction, which is sterically hindered on the OV of the BiOCl (001) surface, and also allow more localized electrons transfer from the OV to the dissociatively adsorbed water, leading to its higher water activation level for hole trapping. These findings highlight the indispensable role of crystalline surface structure on water oxidation and may open up avenues for the rational design of highly efficient photocatalysts via surface engineering. (Chemical Equation Presented).
Catalytic water oxidation based on Ag(i)-substituted Keggin polyoxotungstophosphate
Cui, Ying,Shi, Lei,Yang, Yanyi,You, Wansheng,Zhang, Lancui,Zhu, Zaiming,Liu, Meiying,Sun, Licheng
, p. 17406 - 17415 (2014)
A 1D chain-like Ag(i)-substituted Keggin polyoxotungstophosphate, K3[H3AgIPW11O39]·12H2O, has been synthesized in a high yield and characterized by single-crystal X-ray diffraction, XRD, IR, TG/DTA and elemental analysis. When the polyoxotungstophosphate is dissolved in aqueous solutions, 31P NMR, MS and conductivity analyses indicate that a Ag(i) anion-complex formulated as [H3AgI(H2O)PW11O39]3- is formed and is stable in a solution of pH 3.5-7.0. The oxidation of [H3AgI(H2O)PW11O39]3- by S2O82- has been studied by ESR, UV-Visible spectroscopy, 31P NMR and UV-Raman spectroscopy. It was found that [H3AgI(H2O)PW11O39]3- can be oxidized to dominantly generate a dark green Ag(ii) anion-complex [H3AgII(H2O)PW11O39]2- and a small amount of Ag(iii) complex [H3AgIIIOPW11O39]3-, simultaneously evolving O2. Compared with [AgI(2,2′-bpy)NO3] and AgNO3, [H3AgI(H2O)PW11O39]3- has the higher activity in chemical water oxidation. This illustrates that the [PW11O39]7- ligand plays important roles in both the transmission of electrons and protons, and in the improvement of the redox performance of silver ions. The rate of O2 evolution is a first-order law with respect to the concentrations of [H3AgI(H2O)PW11O39]3- and S2O82-, respectively. A possible catalytic water oxidation mechanism of [H3AgI(H2O)PW11O39]3- is proposed, in which the [H3AgII(H2O)PW11O39]2- and [H3AgIIIOPW11O39]3- intermediates are determined and the rate-determining step is [H3AgIIIOPW11O39]3- oxidizing water into H2O2. This journal is
Mechanisms of water oxidation catalyzed by the cis,cis-[(bpy) 2Ru(OH2)]2O4+ ion
Yamada, Hiroshi,Siems, William F.,Koike, Tohru,Hurst, James K.
, p. 9786 - 9795 (2004)
The cis,cis-[(bpy)2RuIII(OH2)] 2O4+ μ-oxo dimeric coordination complex is an efficient catalyst for water oxidation by strong oxidants that proceeds via intermediary formation of cis,cis-[(bpy)2RuV(O)]2O 4+ (hereafter, {5,5}). Repetitive mass spectrometric measurement of the isotopic distribution of O2 formed in reactions catalyzed by 18O-labeled catalyst established the existence of two reaction pathways characterized by products containing either one atom each from a ruthenyl O and solvent H2O or both O atoms from solvent molecules. The apparent activation parameters for μ-oxo ion-catalyzed water oxidation by Ce4+ and for {5,5} decay were nearly identical, with ΔH? = 7.6 (±1.2) kcal/mol, ΔS? = -43 (±4) cal/deg mol (23 °C) and ΔH? = 7.9 (±1.1) kcal/mol, ΔS? = -44 (±4) cal/deg mol, respectively, in 0.5 M CF3SO3H. An apparent solvent deuterium kinetic isotope effect (KIE) of 1.7 was measured for O2 evolution at 23 °C; the corresponding KIE for {5,5} decay was 1.6. The 32O2/ 34O2 isotope distribution was also insensitive to solvent deuteration. On the basis of these results and previously established chemical properties of this class of compounds, mechanisms are proposed that feature as critical reaction steps H2O addition to the complex to form covalent hydrates. For the first pathway, the elements of H2O are added as OH and H to the adjacent terminal ruthenyl O atoms, and for the second pathway, OH is added to a bipyridine ring and H is added to one of the ruthenyl O atoms.
Cerium(IV)-driven water oxidation catalyzed by a manganese(V)-nitrido complex
Ma, Li,Wang, Qian,Man, Wai-Lun,Kwong, Hoi-Ki,Ko, Chi-Chiu,Lau, Tai-Chu
, p. 5246 - 5249 (2015)
The study of manganese complexes as water-oxidation catalysts (WOCs) is of great interest because they can serve as models for the oxygen-evolving complex of photosystem II. In most of the reported Mn-based WOCs, manganese exists in the oxidation states III or IV, and the catalysts generally give low turnovers, especially with one-electron oxidants such as CeIV. Now, a different class of Mn-based catalysts, namely manganese(V)-nitrido complexes, were explored. The complex [MnV(N)(CN)4]2- turned out to be an active homogeneous WOC using (NH4)2[Ce(NO3)6] as the terminal oxidant, with a turnover number of higher than 180 and a maximum turnover frequency of 6 min-1. The study suggests that active WOCs may be constructed based on the MnV(N) platform. High turnover: The study of manganese complexes as catalysts for the oxidation of water is of great interest as they can serve as models for the oxygen-evolving complex of photosystem II. The manganese(V)-nitrido complex [Mn(N)(CN)4]2- was now shown to catalyze the oxidation of water by cerium(IV) with a turnover number (TON) of higher than 180.
Mechanistic interpretation of CO oxidation turnover rates on supported Au clusters
Ojeda, Manuel,Zhan, Bi-Zeng,Iglesia, Enrique
, p. 92 - 102 (2012)
Kinetic and isotopic data are used to interpret the mechanistic role of gaseous H2O molecules and of non-reducible (Al2O 3) and reducible (TiO2, Fe2O3) supports on CO oxidation turnovers catalyzed by small Au clusters (2O acts as a co-catalyst essential for O2 activation and for catalyst stability in CO oxidation at near-ambient temperatures, but also inhibits rates via competitive adsorption at higher H2O pressures. The effects of CO, O2, and H2O pressures on CO oxidation turnover rates, the absence of 16O2/18O 2 and 16O2/H218O exchange, and the small H2O/D2O kinetic isotope effects are consistent with quasi-equilibrated molecular adsorption of CO, O 2, and H2O on Au clusters with the kinetic relevance of H2O-mediated O2 activation via the formation of hydroperoxy intermediates (OOH), which account for the remarkable reactivity and H2O effects on Au clusters. These elementary steps proceed on Au clusters without detectable requirements for support interface sites, which are no longer required when H2O is present and mediates O2 activation steps. Rate enhancements by H2O were also observed for CO oxidation on Pt clusters (1.3 nm), which is also limited by O2 activation steps, suggesting H2O-aided O2 activation and OOH species in oxidations involving kinetically-relevant O2 activation. These intermediates have also been proposed to account for the ability of O2/H2O mixtures to act as reactants in alkene epoxidation on Au-based catalysts.
Mechanistic studies of the oxygen evolution reaction by a cobalt-phosphate catalyst at neutral pH
Surendranath, Yogesh,Kanan, Matthew W.,Nocera, Daniel G.
, p. 16501 - 16509 (2010)
The mechanism of the oxygen evolution reaction (OER) by catalysts prepared by electrodepositions from Co2+ solutions in phosphate electrolytes (Co-Pi) was studied at neutral pH by electrokinetic and 18O isotope experiments. Low-potential electrodepositions enabled the controlled preparation of ultrathin Co-Pi catalyst films (III-OH and CoIV-O in which a phosphate species is the proton acceptor, followed by a chemical turnover-limiting process involving oxygen-oxygen bond coupling.
