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On the Operando Structure of Ruthenium Oxides during the Oxygen Evolution Reaction in Acidic Media
ACS Catalysis ( IF 12.9 ) Pub Date : 2023-05-19 , DOI: 10.1021/acscatal.3c01607
Nipon Deka, Travis E. Jones, Lorenz J. Falling, Luis-Ernesto Sandoval-Diaz, Thomas Lunkenbein, Juan-Jesus Velasco-Velez, Ting-Shan Chan, Cheng-Hao Chuang, Axel Knop-Gericke, Rik V. Mom

In the search for rational design strategies for oxygen evolution reaction (OER) catalysts, linking the catalyst structure to activity and stability is key. However, highly active catalysts such as IrOx and RuOx undergo structural changes under OER conditions, and hence, structure–activity–stability relationships need to take into account the operando structure of the catalyst. Under the highly anodic conditions of the oxygen evolution reaction (OER), electrocatalysts are often converted into an active form. Here, we studied this activation for amorphous and crystalline ruthenium oxide using X-ray absorption spectroscopy (XAS) and electrochemical scanning electron microscopy (EC-SEM). We tracked the evolution of surface oxygen species in ruthenium oxides while in parallel mapping the oxidation state of the Ru atoms to draw a complete picture of the oxidation events that lead to the OER active structure. Our data show that a large fraction of the OH groups in the oxide are deprotonated under OER conditions, leading to a highly oxidized active material. The oxidation is centered not only on the Ru atoms but also on the oxygen lattice. This oxygen lattice activation is particularly strong for amorphous RuOx. We propose that this property is key for the high activity and low stability observed for amorphous ruthenium oxide.

中文翻译:

酸性介质中析氧反应过程中氧化钌的原位结构

在寻找析氧反应 (OER) 催化剂的合理设计策略时,将催化剂结构与活性和稳定性联系起来是关键。然而,IrO x和 RuO x等高活性催化剂在 OER 条件下发生结构变化,因此,结构-活性-稳定性关系需要考虑催化剂的原位结构。在析氧反应 (OER) 的高阳极条件下,电催化剂通常会转化为活性形式。在这里,我们使用 X 射线吸收光谱 (XAS) 和电化学扫描电子显微镜 (EC-SEM) 研究了非晶和结晶氧化钌的这种活化。我们跟踪了氧化钌中表面氧物种的演变,同时绘制了 Ru 原子的氧化态图,以绘制导致 OER 活性结构的氧化事件的完整图景。我们的数据表明,氧化物中的大部分 OH 基团在 OER 条件下被去质子化,导致高度氧化的活性材料。氧化不仅集中在 Ru 原子上,而且集中在氧晶格上。这种氧晶格活化对于无定形 RuO 特别强×。我们认为,这种特性是观察到无定形氧化钌的高活性和低稳定性的关键。
更新日期:2023-05-19
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