Metal oxide complexes are well known for their potential applications as catalysts in many processes. Manganese-based oxide complexes are studied extensively in development of catalysts for the photochemical water splitting reaction. The doping of manganese oxide complexes with calcium has become popular to mimic the natural water splitting catalyst: the oxygen-evolving complex (OEC) in photosystem II (PS II). Herein, density functional theory (DFT) calculations were performed to study water oxidation processes on fully saturated CaxMn2-xO4-x (x=0,1) complexes. All calculations were performed at the PBE/ATZP level of theory and the geometrical structures and reaction energies of pure and Ca-doped systems were compared. In a catalytic cycle, four proton–coupled electron transfer (PCET) or hydrogen atom transfer (HAT) reactions, a molecular oxygen evolving reaction and two water adsorption reactions were considered. The overall energy required for the dehydrogenation processes is higher than that of oxygen generation and water adsorption processes. The oxygen generation is the highest reaction energy step on Mn2O4 and it is reduced when the complex is doped with a Ca ion.

Theoretical investigation of water oxidation processes on small pure and Ca-doped MnO2 complexes

249th National Meeting (2015)

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