Evaluation of Chromophore and Assembly Design in Light-Driven Water Splitting with a Molecular Water Oxidation Catalyst

The water oxidation catalyst [Ru(bda)(4-O(CH2)(3)P-(O3H2)(2)-pyr)(2)], 1, (pyr = pyridine; bda = 2,2'-bipyridine-6,6'-dicarboxylate) was investigated as the catalyst part of a series of chromophore-catalyst assemblies for light-driven water splitting in dye-sensitized photoelectrosynthesis cells (DSPECs). Both co-loaded and layer-by-layer assemblies with phosphonate-Zr(IV) bridging were investigated on SnO2/TiO2 core-shell electrodes. Device performance was evaluated by both photocurrent and direct O-2 measurements in collector-generator cells. The photoelectrodes displayed impressive photocurrents (0.72-1.5 mA/cm(2)) and Faradaic efficiencies for O-2 generation (71-97%) under 1 sun illumination in pH 5.7, 0.1 M acetate buffer solutions and provided important mechanistic insights into the microscopic details for DSPEC water splitting.