铱
析氧
氧气
光谱学
化学计量学
红外光谱学
化学
催化作用
物理化学
电化学
有机化学
物理
电极
生物化学
量子力学
作者
Na Li,Liang Cai,Guoping Gao,Yue Lin,Chao Wang,Hengjie Liu,Yuying Liu,Hengli Duan,Qianqian Ji,Wei Hu,Hao Tan,Zeming Qi,Lin‐Wang Wang,Wensheng Yan
出处
期刊:Nano Letters
[American Chemical Society]
日期:2022-08-25
卷期号:22 (17): 6988-6996
被引量:20
标识
DOI:10.1021/acs.nanolett.2c01777
摘要
We report Ca2-xIrO4 nanocrystals exhibit record stability of 300 h continuous operation and high iridium mass activity (248 A gIr-1 at 1.5 VRHE) that is about 62 times that of benchmark IrO2. Lattice-resolution images and surface-sensitive spectroscopies demonstrate the Ir-rich surface layer (evolved from one-dimensional connected edge-sharing [IrO6] octahedrons) with high relative content of Ir5+ sites, which is responsible for the high activity and long-term stability. Combining operando infrared spectroscopy with X-ray absorption spectroscopy, we report the first direct observation of key intermediates absorbing at 946 cm-1 (Ir6+═O site) and absorbing at 870 cm-1 (Ir6+OO- site) on iridium-based oxides electrocatalysts, and further discover the Ir6+═O and Ir6+OO- intermediates are stable even just from 1.3 VRHE. Density functional theory calculations indicate the catalytic activity of Ca2IrO4 is enhanced remarkably after surface Ca leaching, and suggest IrOO- and Ir═O intermediates can be stabilized on positive charged active sites of Ir-rich surface layer.
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