氧还原反应
氧还原
电化学
化学
氧气
氧化还原
铂金
无机化学
氧化物
催化作用
电极
还原(数学)
电催化剂
电解
材料科学
循环伏安法
作者
Oliver Rodríguez,Guy Denuault
标识
DOI:10.1002/celc.202100710
摘要
Abstract In this study, we employed microelectrodes and scanning electrochemical microscopy (SECM) to investigate the role of molecular oxygen and local pH changes on the electrochemistry of Pt oxide. We show that in acidic media and alkaline conditions, the impact of O 2 is negligible, while in unbuffered neutral media, O 2 strongly affects the formation of Pt oxides. Experiments carried under hindered diffusion reveal that this is due to a high local pH arising from the oxygen reduction reaction. This is evidenced by the appearance, at very positive potentials, of a diffusion controlled wave consistent with the oxidation of OH − . The ORR produces a sufficiently alkaline environment near the electrode to promote the formation of oxide at much more negative potentials than anticipated from the bulk pH. As a result, the onset of oxide formation overlaps the onset of oxygen reduction and it is impossible to obtain a Pt surface free from oxide at potentials positive of the onset of the ORR. Thus, prior exposure of the Pt surface to dissolved oxygen does not leave irreversibly adsorbed oxygen species as previously reported by our group; instead, the ORR induces a coverage of oxide at much lower potentials than determined by the bulk pH.
科研通智能强力驱动
Strongly Powered by AbleSci AI