Grain Boundaries Boost Oxygen Evolution Reaction in NiFe Electrocatalysts,Small Methods

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Grain Boundaries Boost Oxygen Evolution Reaction in NiFe Electrocatalysts
Small Methods ( IF 10.7 ) Pub Date : 2020-11-03 , DOI: 10.1002/smtd.202000755
Hoon Kee Park ₁ , Hehsang Ahn ₁ , Tae Hyung Lee ₁ , Jae Yoon Lee ₂ , Mi Gyoung Lee ₁ , Sol A Lee ₁ , Jin Wook Yang ₁ , Sang Jun Kim ₁ , Sang Hyun Ahn ₃ , Soo Young Kim ₄ , Chul-Ho Lee ₂ , Eun Soo Park ₁ , Ho Won Jang ₁

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In a polycrystalline material, the grain boundaries (GBs) can be effective active sites for catalytic reactions by providing an electrodynamically favorable surface. Previous studies have shown that grain boundary density is related to the catalytic activity of the carbon dioxide reduction reaction, but there is still no convincing evidence that the GBs provide surfaces with enhanced activity for oxygen evolution reaction (OER). Combination of various electrochemical measurements and chemical analysis reveals the GB density at surface of NiFe electrocatalysts directly affects the overall OER. In situ electrochemical microscopy vividly shows that the OER occurs mainly at the GB during overall reaction. It is observed that the reaction determining steps are altered by grain boundary densities and the meaningful work function difference between the inside of grain and GBs exists. High‐resolution transmission electron microscopy shows that extremely high index planes are exposed at the GBs, enhancing the oxygen evolution activity. The specific nature of GBs and its effects on the OER demonstrated in this study can be applied to the various polycrystalline electrocatalysts.

中文翻译：

晶界促进 NiFe 电催化剂中的析氧反应

在多晶材料中，晶界 (GB) 可以通过提供电动力学有利的表面成为催化反应的有效活性位点。先前的研究表明，晶界密度与二氧化碳还原反应的催化活性有关，但仍然没有令人信服的证据表明 GB 为表面提供了增强的析氧反应 (OER) 活性。各种电化学测量和化学分析的结合揭示了 NiFe 电催化剂表面的 GB 密度直接影响整体 OER。原位电化学显微镜生动地表明，在整个反应过程中，OER 主要发生在 GB 上。观察到反应决定步骤因晶界密度而改变，并且晶粒内部和 GB 之间存在有意义的功函数差异。高分辨率透射电子显微镜显示极高指数平面暴露在 GB 处，增强了析氧活性。本研究中证明的 GB 的特定性质及其对 OER 的影响可应用于各种多晶电催化剂。

更新日期：2020-11-03

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