ABSTRACT
In the present work, we investigate the potential of modified barium titanate (BaTiO3), an inexpensive perovskite oxide derived from earth-abundant precursors, for developing efficient water oxidation electrocatalysts using first-principles calculations. Based on our calculations, Rh doping is a way of making BaTiO3 absorb more light and have less overpotential needed for water to oxidize. It has been shown that a TiO2-terminated BaTiO3 (001) surface is more promising from the point of view of its use as a catalyst. Rh doping expands the spectrum of absorbed light to the entire visible range. The aqueous environment significantly affects the ability of Rh-doped BaTiO3 to absorb solar radiation. After TiâRh replacement, the doping ion can take over part of the electron density from neighboring oxygen ions. As a result, during the water oxidation reaction, rhodium ions can be in an intermediate oxidation state between 3+ and 4+. This affects the adsorption energy of reaction intermediates on the catalyst's surface, reducing the overpotential value.
ABSTRACT
Based on density functional theory and the crystal structure prediction methods, USPEX and AIRSS, stable intermediate compounds in the Ni-X (X = B, C, and N) systems and their structures were determined in the pressure range of 0-400 GPa. It was found that in the Ni-B system, in addition to the known ambient-pressure phases, the new nickel boride, Ni2B3-Immm, stabilizes above 202 GPa. In the Ni-C system, Ni3C-Pnma was shown to be the only stable nickel carbide which stabilizes above 53 GPa. In the Ni-N system, four new phases, Ni6N-R3Ì, Ni3N-Cmcm, Ni7N3-Pbca, and NiN2-Pa3Ì, were predicted. For the new predicted phases enriched by a light-element, Ni2B3-Immm and NiN2-Pa3Ì, mechanical and electronic properties have been studied.