Water Oxidation by Cobalt Centers on Various Oxide Surfaces: The Effects of Oxide Surface Acidity and Oxygen Atom Affinity on Catalysis

Single-atom cobalt centers on various oxide surfaces (TiO2, MgO, SBA-15, AlPO, and Y-Zeolite) were prepared and evaluated as water oxidation catalysts by photochemical water oxidation experiments. Superior catalytic rates were observed for cobalt sites on basic supporting oxides (TiO2 and MgO) relative to those on acidic oxides (Y-Zeolite, AlPO, and SiO2). Per-atom turnover frequencies of ca. 0.04 s-1 were achieved, giving initial rates 100 times greater than that of a surface atom of a Co3O4 nanoparticle. Contrary to expectations based on theoretical work, no apparent correlation was observed between the catalytic rates and the oxygen atom affinities of the supporting oxides. (Graph Presented).