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چکیده
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The research community is investigating fuel producing reactions under electrochemical, photocatlytic, photoelectrochemical, and thermal conditions [1]. The development of effective water oxidation catalysts (WOCs) is of central importance to multiple green energy technologies [2]. As a consequence, a seminal aspect of successful WOC design is a catalyst that can be oxidized or reduced by several electrons with all oxidation states remaining viable under turnover conditions. This is functionally analogous to O2 production in the oxygen evolving center (OEC) of photosystem (II) [3]. Cobalt substituted polyoxometalate, Na12[WCo3(H2O)2(CoW9O34)2] (1) has been shown to catalyze water oxidation to dioxygen with high turnover number and turnover frequency. The catalyst is comprehensively characterized by FT-IR, UV-Vis, X-RD, E.A., TGA, XPS, GC-Mass, etc. All data suggest that the Copolyanion (1) could be an efficient catalyst to oxidize water to dioxygen. To prove this hypothesis we used a visible-light driven system with [Ru(bpy)3]3+ as a photosensitizer and persulfate as a sacrificial electron acceptor. Indeed, we have observed the evolution of dioxygen from water in this system. A very high TON up to 1200 and TOF up to 10 s-1 and quantum efficiency ~18.5% were achieved. To our best knowledge, the complex (1) is the first example of stable and efficient all inorganic homogeneous catalyst based on abundant and cheap transition metals, Co- and W, for photo-driven water oxidation with TON up to 1050
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