Computational Screening of Doped α-MnO₂ Catalysts for the Oxygen Evolution Reaction

Minimizing energy and materials costs for driving the oxygen evolution reaction (OER) is paramount for the commercialization of water electrolysis cells and rechargeable metal-air batteries. Structural stability, catalytic activity, and electronic conductivity of pure and doped α-MnO₂ for the OER are studied using density functional theory calculations. As model surfaces, we investigate the (110) and (100) facets, on which three possible active sites are identified: a coordination unsaturated, a bridge, and a bulk site. For pure and Cr-, Fe-, Co-, Ni-, Cu-, Zn-, Cd-, Mg-, Al-, Ga-, In-, Sc-, Ru-, Rh-, Ir-, Pd-, Pt-, Ti-, Zr-, Nb-, and Sn-doped α-MnO₂ , the preferred valence at each site is imposed by adding/subtracting electron donors (hydrogen atoms) and electron acceptors (hydroxy groups). From a subset of stable dopants, Pd-doped α-MnO₂ is identified as the best catalyst and the only material that can outperform pristine α-MnO₂ . Different approaches to increase the bulk electron conductivity of semiconducting α-MnO₂ are discussed.