In-situ spectroscopic observation of dynamic-coupling oxygen on atomically dispersed iridium electrocatalyst for acidic water oxidation

Hui Su; Wanlin Zhou; Wu Zhou; Yuanli Li; Lirong Zheng; Hui Zhang; Meihuan Liu; Xiuxiu Zhang; Xuan Sun; Yanzhi Xu; Fengchun Hu; Jing Zhang; Tiandou Hu; Qinghua Liu; Shiqiang Wei

doi:10.1038/s41467-021-26416-3

In-situ spectroscopic observation of dynamic-coupling oxygen on atomically dispersed iridium electrocatalyst for acidic water oxidation

Nat Commun. 2021 Oct 21;12(1):6118. doi: 10.1038/s41467-021-26416-3.

Authors

Hui Su^#¹, Wanlin Zhou^#¹, Wu Zhou², Yuanli Li¹, Lirong Zheng³, Hui Zhang¹, Meihuan Liu¹, Xiuxiu Zhang¹, Xuan Sun¹, Yanzhi Xu¹, Fengchun Hu¹, Jing Zhang³, Tiandou Hu³, Qinghua Liu⁴, Shiqiang Wei⁵

Affiliations

¹ National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, Anhui, P. R. China.
² School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University, Shihezi, 832003, China.
³ Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China.
⁴ National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, Anhui, P. R. China. qhliu@ustc.edu.cn.
⁵ National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, Anhui, P. R. China. sqwei@ustc.edu.cn.

^# Contributed equally.

Abstract

Uncovering the dynamics of active sites in the working conditions is crucial to realizing increased activity, enhanced stability and reduced cost of oxygen evolution reaction (OER) electrocatalysts in proton exchange membrane electrolytes. Herein, we identify at the atomic level potential-driven dynamic-coupling oxygen on atomically dispersed hetero-nitrogen-configured Ir sites (AD-HN-Ir) in the OER working conditions to successfully provide the atomically dispersed Ir electrocatalyst with ultrahigh electrochemical acidic OER activity. Using in-situ synchrotron radiation infrared and X-ray absorption spectroscopies, we directly observe that one oxygen atom is formed at the Ir active site with an O-hetero-Ir-N₄ structure as a more electrophilic active centre in the experiment, which effectively promotes the generation of key *OOH intermediates under working potentials; this process is favourable for the dissociation of H₂O over Ir active sites and resistance to over-oxidation and dissolution of the active sites. The optimal AD-HN-Ir electrocatalyst delivers a large mass activity of 2860 A g_metal^-1 and a large turnover frequency of 5110 h^-1 at a low overpotential of 216 mV (10 mA cm^-2), 480-510 times larger than those of the commercial IrO₂. More importantly, the AD-HN-Ir electrocatalyst shows no evident deactivation after continuous 100 h OER operation in an acidic medium.