Identification of the Active-Layer Structures for Acidic Oxygen Evolution from 9R-BaIrO3 Electrocatalyst with Enhanced Iridium Mass Activity

• DOI: 10.1021/jacs.1c04087
• Publication Date: 2021-10-25T15:32:04Z
• Authors: 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
• Keywords: Overpotential; Oxygen evolution; Nanomaterial-based catalyst

Iridium-based perovskites show promising catalytic activity for oxygen evolution reaction (OER) in acid media, but the iridium mass remains low and active-layer structures have not been identified. Here, we report highly active 1 nm IrOx particles anchored on 9R-BaIrO3 (IrOx/9R-BaIrO3) that are directly synthesized by solution calcination followed strong treatment first time. The developed IrOx/9R-BaIrO3 catalyst delivers a high (168 A gIr-1), about 16 times higher than of benchmark acidic OER electrocatalyst IrO2 (10 only requires overpotential 230 mV to reach current density 10 mA cm-2geo. Careful scanning transmission electron microscopy, synchrotron radiation-based X-ray absorption spectroscopy, photoelectron spectroscopy analyses reveal that, during electrocatalytic process, initial nanoparticles/9R-BaIrO3 evolve into amorphous Ir4+OxHy/IrO6 octahedrons then Ir5+Ox/IrO6 surface. Such relative content Ir5+Ox species derived from trimers face-sharing IrO6 enhanced metallic conductivity Ir5+Ox/9R-BaIrO3 responsible excellent activity. Our results provide new insights surface structure perovskite electrocatalysts demonstrate approaches engineering nanocatalysts.