Dual Mechanisms: Hydrogen Transfer during Water Oxidation Catalysis of Pure and Fe-Doped Nickel Oxyhydroxide

Metal oxides are often used as catalysts for the oxygen evolution reaction which is of significant importance for water splitting as an alternative energy source. One of the best performing catalysts reported to date for water oxidation under alkaline conditions is nickel oxyhydroxide (NiOOH) doped with iron. However, NiOOH has hydrogen atoms whose positions are not known and may transfer through the material. In order to understand how hydrogen transfer affects catalytic efficiency, we use density functional theory+U (DFT+U) calculations that model oxygen evolution reaction catalysis for pure and Fe-doped NiOOH. Our calculations reveal that hydrogen transfer is possible in the Fe-doped case but is less probable in the pure case. The duality of proton and charge transfer at the surface of reactive materials provides further evidence to the effectiveness of doping for improving catalysis.