Pyrochlore-type Bi₂Sn₂O₇ oxide as an electrocatalyst for carbon dioxide reduction

Abstract

Pyrochlore-type A₂B₂O_7−z (A = Pb, Bi; B = Nb, Ru, Sn, Ir) oxide fine powders were synthesized by a wet-chemical method. The electrochemical reduction properties of carbon dioxide were investigated with carbon-based gas-diffusion-type electrodes loaded with various pyrochlore-type oxide catalysts. The current–voltage curves under pure CO₂ gas flow showed that the Sn-based pyrochlore-type oxides gave high electrocatalytic activities for the electrochemical CO₂ reduction. Among the pyrochlore-type oxides tested, Bi₂Sn₂O₇ showed the highest CO₂ reduction reaction which gave CO as a main product at very high concentration. XPS analyses showed that the high performance for the electrochemical CO₂ reduction of Bi₂Sn₂O₇ was come from the valence state of Sn and/or oxygen adsorption–desorption properties of the pyrochlore-type oxide.