酸化物電極触媒の計算予測

抄録

Defective oxide electrocatalysts are gaining attention as a platinum substitute for the hydrogen fuel cell. Oxygen reduction reaction (ORR) catalyzed at the surface is predicted using an exhaustive first-principles approach. After investigating the equilibrium distribution of the oxygen vacancies and nitrogen impurities at a tetragonal ZrO₂(101), adsorption energy of the ORR intermediates was calculated. The free energy profile depends on the defect configuration. The profile obtained for stable configurations showed that the rate-determining step is the removal of OH and the heat of the reaction is comparable to that of the defect-free surface. It is thus suggested that the role of the defects in enhancing the current density observed experimentally is possibly due to enhanced carrier supply through a defect-induced gap state.