La-based Perovskite-type Oxide Catalysts for Electrochemical Reduction of Oxygen in Alkaline Solution

Poly (tetrafluoroethylene) (PTFE) -bounded carbon electrode loaded with La-based perovskite-type oxides (La_1- _xA_xBO_3) were systematically investigated for developing high performance electrodes for electrochemical reduction of oxygen. The electrode performance was largely affected by the kind of A, B, -site elements as well as x of the oxide compound, and the best results, were obrained with the compounds La_<0.8>Sr_<0.2>MO_3 (M=Co,Mn). The electrode activity was found to be roughly determined by the ability of the perovskite oxide to decompose the HO_2^- intermediate. Based on these results high performance gas diffusion electrodes could be fabricated, the reaction layer which contained as much as 60 wt% oxide catalysts