Light-Driven Water Splitting with a Molecular Electroassembly-Based Core/Shell Photoanode

An electrochemical procedure for preparing chromophore-catalyst assemblies on oxide electrode surfaces by reductive vinyl coupling is described. On core/shell SnO2/TiO2 nanoparticle oxide films, excitation of the assembly with 1 sun (100 mW cm(-2)) illumination in 0.1 M H2PO4-/HPO42- at pH 7 with an applied bias of 0.4 V versus SCE leads to water splitting in a DSPEC with a Pt cathode. Over a 5 min photolysis period, the core/shell photoanode produced O-2 with a faradaic efficiency of 22%. Instability of the surface bound chromophore in its oxidized state in the phosphate buffer leads to a gradual decrease in photocurrent and to the relatively modest faradaic efficiencies.