Structural Dynamics of Ultrathin Cobalt Oxide Nanoislands under Potential Control
Structural Dynamics of Ultrathin Cobalt Oxide Nanoislands under Potential Control
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DOI：
10.1002/adfm.202009923
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发表时间：
2021-01
影响因子：
19
通讯作者：
Corinna Stumm;M. Bertram;Maximilian Kastenmeier;F. Speck;Zhaozong Sun;J. Rodrı́guez-Fernández;J. Laurits
中科院分区：
文献类型：
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作者：
Corinna Stumm;M. Bertram;Maximilian Kastenmeier;F. Speck;Zhaozong Sun;J. Rodrı́guez-Fernández;J. Laurits
钴氧化物是一种极具应用前景的电催化剂，也是电催化领域研究最多的氧化物之一。在这项研究中，在电位控制下原位研究了Au（111）上轮廓分明的钴氧化物纳米岛（NI）的结构动力学。样品在超高真空中制备，并使用扫描隧道显微镜（STM）对系统进行表征。转移到电化学环境中后，通过原位电化学（EC）STM、循环伏安法和EC在线电感耦合等离子体质谱法研究其结构、迁移率和溶解。Au（111）上的氧化钴形成双层（BL）和双双层NI（DL），其在开路电位（0.8 VRHE）下稳定。在阴极扫描中，钴氧化物BL岛在0.5 VRHE的电势下变得移动的，并且在低于0.5 VRHE的电势下开始溶解。与BL岛形成鲜明对比的是，DL岛在低得多的电位下仍保持其形态。观察到Co聚集体的再沉积接近于Co2+至Co3+的还原电位。在阳极扫描中，BL岛和DL岛都保持其形态直到1.5 VRHE。即使在这些条件下，岛在析氧反应（OER）期间也不显示溶解，同时保持其高OER活性。
Cobalt oxide is a promising earth abundant electrocatalyst and one of the most intensively studied oxides in electrocatalysis. In this study, the structural dynamics of well‐defined cobalt oxide nanoislands (NIs) on Au(111) are investigated in situ under potential control. The samples are prepared in ultra‐high vacuum and the system is characterized using scanning tunneling microscopy (STM). After transfer into the electrochemical environment, the structure, mobility, and dissolution is studied via in situ electrochemical (EC) STM, cyclic voltammetry, and EC on‐line inductively coupled plasma mass spectrometry. Cobalt oxide on Au(111) forms bilayer (BL) and double‐bilayer NIs (DL), which are stable at the open circuit potential (0.8 VRHE). In the cathodic scan, the cobalt oxide BL islands become mobile at potentials of 0.5 VRHE and start dissolving at potentials below. In sharp contrast to the BL islands, the DL islands retain their morphology up to much lower potential. The re‐deposition of Co aggregates is observed close to the reduction potential of Co2+ to Co3+. In the anodic scan, both the BL and DL islands retain their morphology up to 1.5 VRHE. Even under these conditions, the islands do not show dissolution during the oxygen evolution reaction (OER) while maintaining their high OER activity.