X射线吸收光谱法
化学
氧烷
循环伏安法
价(化学)
双金属片
催化作用
氧化物
电化学
氧化态
吸收光谱法
氧气
无机化学
扩展X射线吸收精细结构
X射线光电子能谱
同步加速器
分析化学(期刊)
氧化还原
光谱学
吸收(声学)
物理化学
电极
化学工程
材料科学
工程类
复合材料
物理
量子力学
有机化学
核物理学
生物化学
色谱法
作者
Yao Yang,Ying Wang,Yin Xiong,Xin Huang,Luxi Shen,Rong Huang,Hongsen Wang,James Pastore,Seung‐Ho Yu,Li Xiao,J. D. Brock,Héctor D. Abruña
摘要
Identifying the catalytically active site(s) in the oxygen reduction reaction (ORR), under real-time electrochemical conditions, is critical to the development of fuel cells and other technologies. We have employed in situ synchrotron-based X-ray absorption spectroscopy (XAS) to investigate the synergistic interaction of a Co–Mn oxide catalyst which exhibits impressive ORR activity in alkaline fuel cells. X-ray absorption near edge structure (XANES) was used to track the dynamic structural changes of Co and Mn under both steady state (constant applied potential) and nonsteady state (potentiodynamic cyclic voltammetry, CV). Under steady state conditions, both Mn and Co valences decreased at lower potentials, indicating the conversion from Mn(III,IV) and Co(III) to Mn(II,III) and Co(II), respectively. Rapid X-ray data acquisition, combined with a slow sweep rate in CV, enabled a 3 mV resolution in the applied potential, approaching a nonsteady (potentiodynamic) state. Changes in the Co and Mn valence states were simultaneous and exhibited periodic patterns that tracked the cyclic potential sweeps. To the best of our knowledge, this represents the first study, using in situ XAS, to resolve the synergistic catalytic mechanism of a bimetallic oxide. Strategies developed/described herein can provide a promising approach to unveil the reaction mechanism for other multimetallic electrocatalysts.
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