Unravelling Hydrogen Adsorption Kinetics on Ir(111) Electrode in Acid Solutions by Impedance Spectroscopy

• 作者: Yan-li Tang Wei Chen Mian-le Xu Zhen Wei Jun Cai Yan-xia Chen
• 来源期刊: 化学物理学报（英文版）
• 年，卷（期）: 2021,（2）
• 所属期刊栏目: ARTICLE
• 页码范围: 179-187
• 页数: 9页
• 语种: 英文
• DOI: 10.1063/1674-0068/cjcp2006105

摘要

The kinetics for hydrogen (H) adsorption on Ir(111) electrode has been studied in both HClO4 and H2SO4 solutions by impedance spectroscopy.In HClO4,the adsorption rate for H adsorption on Ir(111) increases from 1.74× 10-8 mol.cm-2·s-1 to 3.47× 10-7 mol·cm-2·s-1 with the decrease of the applied potential from 0.2 V to 0.1 V (vs.RHE),which is ca.one to two orders of magnitude slower than that on Pt(111) under otherwise identical condition.This is explained by the stronger binding of water to Ir(111),which needs a higher barrier to reorient during the under potential deposition of H from hydronium within the hydrogen bonded water network.In H2SO4,the adsorption potential is ca.200 mV negatively shifted,accompanied by a decrease of adsorption rate by up to one order of magnitude,which is explained by the hindrance of the strongly adsorbed sulfate/bisulfate on Ir(111).Our results demonstrate that under electrochemical environment,H adsorption is strongly affected by the accompanying displacement and reorientation of water molecules that initially stay close to the electrode surface.