Facile method to synthesize water oxidation catalyst from polyoxometalate for solar energy storage system

Abstract

Water oxidation is the key to efficient conversion of solar energy to chemical fuels in artificial photosynthesis since it can provide electrons and protons for further chemical reactions. To promote electron transfer across the solid-electrolyte interface (SEI), water oxidation catalysts (WOCs) are often introduced on semiconducting photoanodes to facilitate the four-electron water oxidation reaction. Here, we report a simple method to synthesize efficient and stable WOCs through simple heat treatment of polyoxometalates (POMs). Amorphous and crystalline transition metal tungstate nanoparticles were readily formed by heat treatment of transition metal substituted polyoxometalate at 400 and 500 oC, respectively. It was found that amorphous metal tungstates have a higher catalytic activity than crystalline ones and can be readily deposited on a photoelectrode by simple annealing process. We believe that this results provide a simple and universal method to synthesize and deposit WOCs on photoelectrode for stable and improved water oxidation reaction.