Visible Light-induced Ce (Ⅳ) Oxidation Kinetics Of Oxygen Water Discharge

Ce（Ⅳ） ions are commonly used as an oxidant to oxidize water into O₂. It is significantacademically for understanding of mechanism of catalytic water oxidation of Ce（Ⅳ） and fordevoleping highly efficient catalysts of water oxidation.In this paper, we have found that visible light can induce the water oxidation of Ce（Ⅳ）availably. The rates of O₂evolution increase with the increase of reaction temperatures. Therate is a first order with respect to concentrations of Ce（Ⅳ） ions, namely,4d[O₂]/dt=-d[Ce（Ⅳ）]/dt=k[Ce（Ⅳ）], where k=2.19×10^-2h^-1at25（±0.5）℃. By means of EIS-MS、UV-vis、ESR et., mechanism of Ce（Ⅳ） oxidation of water is deduced. When [CeⅣ（NO3）5]-solution is irradiated by visible light, NO3radicals may be produced, and then oxygenatewater.Two polyoxotungstate-templated Mo/V-oxide-based organic–inorganic hybridcompounds,[Mo₂V₂O₉（bpy）₆][SiW₁₂O₄₀]1and [Mo₂V₂O₉（bpy）₆][PW₁₁VO₄₀]2, have beensynthsized and characterized. They are isomorphic and consist of classical Kegginpolyoxotungstate anions and a novel Mo/V-oxide-based cationic species,[Mo₂V₂O₉（bpy）₆]4+.Electrochemical measurement of1and2shows three pairs of semi-reversible centers, redoxpeaks II–II`and III–III`correspond to processes of W centers and peak I–I`corresponds toprocess of Mo center.1and2were found to be active in the benzene hydroxylation usingoxygen as the oxidant, with TEMPO. Both1and2exhibit good catalytic activities with above99%selectivity for phenol. The yields of phenol can reach up to6.13%and6.33%（entry1and2）, respectively.[Mo₂V₂O₉（bpy）₆]⁴⁺should be truly reactive parts.