Identification of the Active-Layer Structures for Acidic Oxygen Evolution from 9R-BaIrO 3 Electrocatalyst with Enhanced Iridium Mass Activity

作者：Na Li, Liang Cai, Chao Wang, Yue Lin, Jinzhen Huang, Hongyuan Sheng, Haibin Pan, Wei Zhang, Qianqian Ji, Hengli Duan, Wei Hu, Wenhua Zhang, Fengchun Hu, Hao Tan, Zhihu Sun, Bo Song, Song Jin, Wensheng Yan · 发表于：Journal of the American Chemical Society · 年份：2021 · DOI：10.1021/jacs.1c04087 · 被引用次数：166 · 研究领域：Electrocatalysts for Energy Conversion、Fuel Cells and Related Materials、Perovskite Materials and Applications

Iridium-based perovskites show promising catalytic activity for oxygen evolution reaction (OER) in acid media, but the iridium mass activity remains low and the active-layer structures have not been identified. Here, we report highly active 1 nm IrO x particles anchored on 9R-BaIrO 3 (IrO x /9R-BaIrO 3 ) that are directly synthesized by solution calcination followed by strong acid treatment for the first time. The developed IrO x /9R-BaIrO 3 catalyst delivers a high iridium mass activity (168 A g Ir –1 ), about 16 times higher than that of the benchmark acidic OER electrocatalyst IrO 2 (10 A g Ir –1 ), and only requires a low overpotential of 230 mV to reach a catalytic current density of 10 mA cm –2 geo . Careful scanning transmission electron microscopy, synchrotron radiation-based X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy analyses reveal that, during the electrocatalytic process, the initial 1 nm IrO x nanoparticles/9R-BaIrO 3 evolve into amorphous Ir 4+ O x H y /IrO 6 octahedrons and then to amorphous Ir 5+ O x /IrO 6 octahedrons on the surface. Such high relative content of amorphous Ir 5+ O x species derived from trimers of face-sharing IrO 6 octahedrons in 9R-BaIrO3 and the enhanced metallic conductivity of the Ir 5+ O x /9R-BaIrO 3 catalyst are responsible for the excellent acidic OER activity. Our results provide new insights into the surface active-layer structure evolution in perovskite electrocatalysts and demonstrate new approaches for e...