Concerted Proton–Electron Transfer Reaction for ORR on Au in Acid Solution: An ATR-SEIRAS Investigation

摘要

The oxygen reduction reaction (ORR) is important in electrochemical (EC) energy conversion devices such as fuel cells. ORR is challenging due to a complex mechanism and kinetics by electron transfer (ET) and proton transfer (PT) reactions on heterogeneous metallic surfaces in alkaline and acidic solutions. Bard and coworkers confirmed that the formation of O_2~– was the first elementary step of ORR by EC methods in strong basic solution. Spectroscopic evidence of O_2~– has been reported in basic or aprotic electrolyte solutions on Pt by ATR-SEIRAS. However, little spectroscopic evidence exists for ORR intermediates in acidic solutions, primarily due to the fast protonation and short lifetime of O_2~–. The observation of a proton donor appears to be even more challenging on EC interfaces in the PT process which is another important feature of ORR. In this presentation, we will discuss the first spectroscopic evidence of a concerted PT-ET reaction (CPETR) on Au in acidic solution.