Morphological and Structural Evolution of Co3O4 Nanoparticles Revealed by in Situ Electrochemical Transmission Electron Microscopy during Electrocatalytic Water Oxidation
Morphological and Structural Evolution of Co3O4 Nanoparticles Revealed by in Situ Electrochemical Transmission Electron Microscopy during Electrocatalytic Water Oxidation
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DOI：
10.1021/acsnano.9b04745
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发表时间：
2019-10-01
期刊：
影响因子：
17.1
通讯作者：
Ersen, Ovidiu
中科院分区：
文献类型：
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作者：
Pena, Nathaly Ortiz;Ihiawakrim, Dris;Ersen, Ovidiu
揭示电催化过程的机理是寻找更高效、更稳定的清洁能源转换装置电极材料的基础。虽然现在有几种原位技术可用于跟踪电催化过程中的结构变化，特别是水的氧化，但在真实的空间中，纳米结构电催化剂的形态变化的直接观察是缺失的。在这里，我们实现了原位电化学透射电子显微镜（在原位EC-TEM）的方法，用于研究在操作过程中的析氧反应（OER）的电催化剂，通过使用模型钴氧化物Co 3 O 4纳米粒子。的观察条件进行了优化，以模仿标准的电化学实验中的一个定期的电化学电池，允许循环伏安法和计时电位法进行原位和非原位在类似的条件。这种原位EC-TEM方法使我们能够观察暴露于不同水性电解质和OER条件下的初始纳米颗粒基电极中发生的化学、形态和结构演变。结果表明，表面发生非晶化，产生纳米钴（羟基）氧化物在OER相。这个过程是不可逆的，并且发生到以前没有描述过的程度。此外，我们表明，pH值和抗衡离子的电解质的影响这种重构，揭示了中性磷酸盐电解质中的材料性能。除了在电化学测量过程中的结构变化，这项研究表明，它是可以依靠在原位电化学TEM揭示过程中的电催化剂，同时保持良好的相关性与非原位常规电化学。
Unveiling the mechanism of electrocatalytic processes is fundamental for the search of more efficient and stable electrode materials for clean energy conversion devices. Although several in situ techniques are now available to track structural changes during electrocatalysis, especially of water oxidation, a direct observation, in real space, of morphological changes of nanostructured electrocatalysts is missing. Herein, we implement an in situ electrochemical Transmission Electron Microscopy (in situ EC-TEM) methodology for studying electrocatalysts of the oxygen evolution reaction (OER) during operation, by using model cobalt oxide Co3O4 nanoparticles. The observation conditions were optimized to mimic standard electrochemistry experiments in a regular electrochemical cell, allowing cyclic voltammetry and chronopotentiometry to be performed in similar conditions in situ and ex situ. This in situ EC-TEM method enables us to observe the chemical, morphological, and structural evolutions occurring in the initial nanoparticle-based electrode exposed to different aqueous electrolytes and under OER conditions. The results show that surface amorphization occurs, yielding a nanometric cobalt (oxyhydr)oxide-like phase during OER. This process is irreversible and occurs to an extent that has not been described before. Furthermore, we show that the pH and counterions of the electrolytes impact this restructuration, shedding light on the materials properties in neutral phosphate electrolytes. In addition to the structural changes followed in situ during the electrochemical measurements, this study demonstrates that it is possible to rely on in situ electrochemical TEM to reveal processes in electrocatalysts while preserving a good correlation with ex situ regular electrochemistry.