Direct synthesis of barium titanium oxyhydride promising for electrode material with hydrogen permeability

Barium titanium oxyhydride BaTiO3–xHx is a promising functional material that exhibits H–/e– mixed conduction and catalytic activity. Here we firstly report a direct synthesis of BaTiO3–xHx by mechanochemical method. The prepared polycrystalline sample was able to work as electrodes exhibiting hydrogen pearmeability

Systematic Study of Descriptors for Oxygen Evolution Reaction Catalysis in Perovskite Oxides

Ever-proposed descriptors of catalytic activity for the oxygen evolution reaction (OER) were systematically investigated. A wide variety of stoichiometric perovskite oxides ABO3 (A = Ca, Sr, Y, La; B = Ti, V, Cr, Mn, Fe, Co, Ni, Cu) were examined as OER catalysts. The simplest descriptor, eg, electron number of transition-metal ions at the B-site, was not applicable for OER overpotentials (η) of the compounds tested in this study. Another descriptor, oxygen 2p band center relative to Fermi energy (ε2p), was not necessarily adequate for the most part of perovskite oxides. Eventually, a recently proposed descriptor, charge-transfer energy (Δ), displayed a linear relationship with η most reasonably. Because Δ values were obtained from theoretical calculations, not only by spectroscopic experiments, systematic exploration for a wide range of compounds including hypothetical ones could be allowed. This finding proposes the charge-transfer energy as the most helpful descriptor for the design of perovskite oxide catalysts for the OER