物理化学学报 >> 2023, Vol. 39 >> Issue (2): 2207035.doi: 10.3866/PKU.WHXB202207035

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微秒时间分辨的工况电化学紫外可见吸收光谱测量系统

尉瑞芳1,2, 李东峰2,3, 尹恒2, 王秀丽2,*(), 李灿1,2,3,*()   

  1. 1 中国科学技术大学化学物理系, 合肥 230026
    2 中国科学院大连化学物理研究所催化基础国家重点实验室, 辽宁 大连 116023
    3 中国科学院大学, 北京 100049
  • 收稿日期:2022-07-15 录用日期:2022-09-05 发布日期:2022-09-08
  • 通讯作者: 王秀丽,李灿 E-mail:xiuliwang@dicp.ac.cn;canli@dicp.ac.cn
  • 基金资助:
    国家重点研发计划(2021YFA1500600);大连化学物理研究所创新基金(DICP I202122)

Operando Electrochemical UV-Vis Absorption Spectroscopy with Microsecond Time Resolution

Ruifang Wei1,2, Dongfeng Li2,3, Heng Yin2, Xiuli Wang2,*(), Can Li1,2,3,*()   

  1. 1 Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
    2 State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning Province, China
    3 University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2022-07-15 Accepted:2022-09-05 Published:2022-09-08
  • Contact: Xiuli Wang,Can Li E-mail:xiuliwang@dicp.ac.cn;canli@dicp.ac.cn
  • About author:Email: canli@dicp.ac.cn (C.L.). +86-411-84379070 (C.L.)
    Email: xiuliwang@dicp.ac.cn (X.W.); Tel.: +86-411-84379027 (X.W.)
  • Supported by:
    the National Key R & D Program of China(2021YFA1500600);the DICP Foundation of Innovative Research(DICP I202122)

摘要:

工况光谱表征技术是深入理解电催化反应机理的有效手段,但是目前所使用的大多数工况表征技术都是基于(准)稳态的光谱技术,对发生在毫微秒时间尺度的瞬态变化过程很难直接进行观测。本研究通过在时间分辨紫外可见吸收光谱系统中引入电压脉冲,并在时间上同步电脉冲信号与光谱信号,实现了时间分辨率高达3 μs的工况电化学紫外可见吸收光谱测量系统。利用此光谱系统和方法研究了水合铁等电催化剂的水氧化动力学机理,直接揭示了电催化剂表面水氧化中间物种在毫微秒时间尺度的形成、转化和反应动力学。微秒时间分辨的工况电化学紫外可见吸收光谱,可以促进电催化反应动力学机理的研究和认识,指导新型高效电催化剂的设计合成。

关键词: 电催化, 工况电化学, 紫外可见吸收光谱, 电脉冲, 时间分辨

Abstract:

Operando spectroscopic characterization is effective for examining electrocatalytic reaction mechanisms. However, most operando characterization techniques currently used are based on (quasi-)steady-state spectroscopy, which often cannot directly measure transient changes occurring on the micro-millisecond time scale. Herein, an operando electrochemical UV-Vis absorption spectroscopy with 3 μs time resolution was realized by introducing bias pulses and synchronizing the bias pulse and spectral signals. Comparing the time-dependence curves of the bias pulse, collected spectral curve, and controlling voltage, a good time consistence for the three signals was observed, demonstrating the time-resolved ability of the novel apparatus. More importantly, two oxidation reactions, water oxidation reaction and hole sacrifice reagent oxidation reaction, showed distinct dynamics, verifying the reliability of the time-resolved kinetics. The water oxidation kinetics on a ferrihydrite (Fh) electrocatalyst were studied by this novel operando spectroscopic system. Different water oxidation steps were decoupled by analyzing the accumulation and decay dynamics of the operando time-resolved UV-Vis absorption data with various pulse widths and magnitudes of applied bias. A long bias pulse with width above 1s enabled the continuous accumulation of reaction intermediates in Fh electrocatalyst to reach a quasi-equilibrium state with electron extraction into the external circuit. In addition, a fast decay for water oxidation was observed after the applied bias was turned off. Importantly, when a short bias pulse with tens of ms width was applied, an abnormal intermediate accumulation process was observed after the applied bias was shut off, revealing a spontaneous species transformation process. These results confirm the validity of this novel method for examining species transformation kinetics at a fast timescale. The formation, transformation, and reaction kinetics of water oxidation reaction intermediates were directly studied on a µs to s time scale. Therefore, operando electrochemical UV-Vis absorption spectroscopy with µs time resolution can promote the understanding of various electrocatalytic reaction mechanisms and be used to guide the design and synthesis of novel high-efficiency electrocatalysts.

Key words: Electrocatalysis, Operando electrochemistry, UV-Vis absorption spectroscopy, Bias pulse, Time-resolved

MSC2000: 

  • O643