Effects of Oxygen Vacancies and Reaction Conditions on Oxygen Reduction Reaction on Pyrochlore-Type Lead-Ruthenium Oxide

Abstract

© The Author(s) 2014. A series of pyrochlore-type lead-ruthenium oxide (Pb2Ru2O7-δ) containing various amounts of oxygen vacancies was prepared by varying the heat-treatment temperature, and the oxygen reduction reaction (ORR) activity as well as the electrochemical redox property in acid and alkaline solution was evaluated using rotating disk electrode. The specific ORR activity was increased with increasing the amount of oxygen vacancies, and linearly correlated to the charge amount of electrochemical redox of Pb2Ru2O7-δboth in acid and alkaline solution. We concluded that the surface oxygen vacancy participates in the electrochemical redox of Pb2Ru2O7-δ, and at the same time, behaves as the active site for ORR. The ORR activity in alkaline solution was much higher than that in acid solution, possibly because of the difference of the facility of electrochemical desorption of adsorbed oxygen species in the ORR process. Additionally, the effect of humidity on the ORR activity was investigated by single cell test. It was revealed that Pb2Ru2O7-δshows absolutely high ORR activity in dry condition.