Catalytic activity for electrochemical reduction of oxygen of lanthanum nickel oxide and related oxides

Abstract

The catalytic activity for oxygen reduction of lanthanum nickel oxide was affected by the kind and amount of the substituted transition metal M to give LaNi 1− x M x O 3, where M is either one of Fe, Co or V. It was found that the catalytic activity was definitely influenced by the overlap integral between the e g orbital of the transition metal and the sp σ orbital of oxygen, and that the larger the overlap integral is, the higher the electrocatalytic activity. The plausible rate determining step in a low polarization region is MO 2H+ e→MO 2H −, and in a high polarization region the step of oxygen adsorption. Importance of the overlap integral to electrocatalysis is discussed by applying the theory of σ * band formation of the oxide to interaction between the e g orbital of the transition metal of the oxide and the molecular orbital of an oxygen molecule adsorbed on the electrode surface.