Development And Study Of Co/Ni/Cu Based Water Oxidation Catalysts

Transitional metal substituted polyoxometalates represent a group of promising water oxidation catalyst (WOC), especially when using as stable homogeneous molecular catalysts for mechanism studies. They are all inorganic complexes, which are robust enough to survive in the harsh oxidation environment. Moreover, the incorporated transitional metals are endowed with some unique physical and chemical features, because of the influenced of the inorganic POM ligand. On the other hand, although the exploration of WOCs remains at a fundamental stage, much effort has been made on the developing of WOC devices. This paper was divided into three parts including developing of Co/Ni/Cu substituted POMs as photo-catalytic WOCs and preparation of Co3O4 based anode for electro-catalytic water oxidation.1. A series of mono-substituted POMs and two reported POM-based WOCs were synthesized and characterized. Their water oxidation catalytic activities were evaluated with a Ru(bpy)32+/visible light/Na2S2O8 photo-catalytic water oxidation system. Multiple experimental results demonstrate that POM-1 is an efficient and robust WOC. The mono-substitution feature and unique complex environment of POM-1 make it a fascinating candidate for further exploration.2. Nine Ni-substituted and five Cu-substituted POMs were synthesized, characterized and used as photo-catalytic water oxidation catalysts. Unfortunately, none of them appeared active in the Ru(bpy)32+/visible light/Na2S2O8 system.3. A hydrothermal route was used for the preparation of Pt nanoparticle doped Co3O4 nano-arrays on conductive FTO glass substrates. Electrochemical water oxidation experiments with these anodes revealed that there was no difference between doped and non-doped samples. Characterization of these samples found that the failure of the doping process was the main reason.