Photocatalytic Water Oxidation Using Manganese Compounds Immobilized in Nafion Polymer Membranes

Robust water oxidation catalysts using earth abundant metals are required as part of an overall scheme to convert sunlight into fuels. Here, we report the immobilization of [(Mn4O5)-O-IV(terpy)(4)(H2O)(2)](ClO4)(6) (terpy=2,2'; 6',2 ''-terpyridine), [Mn4O6(tacn)(4)](ClO4)(4) (tacn=1,4,7-triazacyclononane), and manganese dioxide nanoparticles in Nafion on fluorine-doped tin oxide conducting glass electrodes. The electrodes are illuminated with white light in the presence of an applied potential and the resulting photocurrent is assigned to the oxidation of solvent water. Photodecomposition of the tetrameric complexes results in a material that is more active for light-driven electrooxidation of water. The reactivity, wavelength dependence, and stability of the compounds in Nafion under illumination are discussed.