SCI和EI收录∣中国化工学会会刊

中国化学工程学报 ›› 2023, Vol. 54 ›› Issue (2): 173-179.DOI: 10.1016/j.cjche.2022.04.012

• Full Length Article • 上一篇    下一篇

Understanding the hydroxyl adsorption behavior at Pt electrode surface in high-temperature alkaline solutions

Bo Pan1, Biao Liu1, Shaona Wang1, Yeqing Lv1, Hao Du1,2, Yi Zhang1,2   

  1. 1. National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China;
    2. University of Chinese Academy of Sciences, Beijing 100190, China
  • 收稿日期:2021-07-12 修回日期:2022-04-05 出版日期:2023-02-28 发布日期:2023-05-11
  • 通讯作者: Hao Du,E-mail:bopan@ipe.ac.cn
  • 基金资助:
    The authors gratefully acknowledge the National Key Research and Development Program of China (2020YFC1909703), S&T Program of Hebei Province (21284402Z), Fangchenggang Key Research and Development (AB20014008), and Lvliang Key Research and Development Program (2020GXZDYF7).

Understanding the hydroxyl adsorption behavior at Pt electrode surface in high-temperature alkaline solutions

Bo Pan1, Biao Liu1, Shaona Wang1, Yeqing Lv1, Hao Du1,2, Yi Zhang1,2   

  1. 1. National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China;
    2. University of Chinese Academy of Sciences, Beijing 100190, China
  • Received:2021-07-12 Revised:2022-04-05 Online:2023-02-28 Published:2023-05-11
  • Contact: Hao Du,E-mail:bopan@ipe.ac.cn
  • Supported by:
    The authors gratefully acknowledge the National Key Research and Development Program of China (2020YFC1909703), S&T Program of Hebei Province (21284402Z), Fangchenggang Key Research and Development (AB20014008), and Lvliang Key Research and Development Program (2020GXZDYF7).

摘要: Since the application in fuel cell, the electrochemical adsorption of hydroxyl has received considerable attention in recent years. While most research mainly focus on the room temperature, in this paper, the electrochemical adsorption of hydroxyl in alkaline solution at high temperature was investigated. An unusual oxidation peak was observed at -0.27 V, suggesting new behavior of hydroxyl adsorption occurred. As is known two kinds of cation hydrated clusters exist in alkaline solution, (H2O)x-1M+-H2O-OadH and (H2O)xM+-OadH. For K+ and Cs+, the cluster shows unstable structure due to the weak interaction between hydrated cation and OH- especially at high temperature. However, For Li+, Na+ the cluster structure would be stable, as the interaction force between the hydrated cation and OH- is so strong. It was revealed that the unusual oxidation peak has some relationship with the (H2O)x-1M+-H2O-OadH cluster (K+ and Cs+) absorbed at Pt electrode surface. When the temperature was raised, (H2O)x-1M+-H2O- and -OadH was disconnected, then the OadH absorbed at Pt surface got oxidated. Based on the SEM observation, it was showed the unusual electrochemical oxidation reaction would generate platinum oxides, blocking the reactive sites at Pt electrode surface, thus reducing the electrochemical reactivity of Pt electrode. Accordingly, parameters of alkaline concentration and temperature were systematically studied, it was found that increase temperature or alkaline concentration was in favor of the unusual oxidation reaction. This study provides more understanding of hydroxyl adsorption behavior at Pt electrode surface for the high temperature water solution environment.

关键词: Alkaline solution, Hydroxyl adsorption, Cationic species, High temperature, Cationic hydrated clusters

Abstract: Since the application in fuel cell, the electrochemical adsorption of hydroxyl has received considerable attention in recent years. While most research mainly focus on the room temperature, in this paper, the electrochemical adsorption of hydroxyl in alkaline solution at high temperature was investigated. An unusual oxidation peak was observed at -0.27 V, suggesting new behavior of hydroxyl adsorption occurred. As is known two kinds of cation hydrated clusters exist in alkaline solution, (H2O)x-1M+-H2O-OadH and (H2O)xM+-OadH. For K+ and Cs+, the cluster shows unstable structure due to the weak interaction between hydrated cation and OH- especially at high temperature. However, For Li+, Na+ the cluster structure would be stable, as the interaction force between the hydrated cation and OH- is so strong. It was revealed that the unusual oxidation peak has some relationship with the (H2O)x-1M+-H2O-OadH cluster (K+ and Cs+) absorbed at Pt electrode surface. When the temperature was raised, (H2O)x-1M+-H2O- and -OadH was disconnected, then the OadH absorbed at Pt surface got oxidated. Based on the SEM observation, it was showed the unusual electrochemical oxidation reaction would generate platinum oxides, blocking the reactive sites at Pt electrode surface, thus reducing the electrochemical reactivity of Pt electrode. Accordingly, parameters of alkaline concentration and temperature were systematically studied, it was found that increase temperature or alkaline concentration was in favor of the unusual oxidation reaction. This study provides more understanding of hydroxyl adsorption behavior at Pt electrode surface for the high temperature water solution environment.

Key words: Alkaline solution, Hydroxyl adsorption, Cationic species, High temperature, Cationic hydrated clusters