Self-Nanocavity-Confined Halogen Anions Boosting the High Selectivity of the Two-Electron Oxygen Reduction Pathway over Ni-Based MOFs

Meihuan Liu; Yuanli Li; Zeming Qi; Hui Su; Weiren Cheng; Wanlin Zhou; Hui Zhang; Xuan Sun; Xiuxiu Zhang; Yanzhi Xu; Yong Jiang; Qinghua Liu; Shiqiang Wei

doi:10.1021/acs.jpclett.1c01981

Self-Nanocavity-Confined Halogen Anions Boosting the High Selectivity of the Two-Electron Oxygen Reduction Pathway over Ni-Based MOFs

J Phys Chem Lett. 2021 Sep 16;12(36):8706-8712. doi: 10.1021/acs.jpclett.1c01981. Epub 2021 Sep 2.

Authors

Meihuan Liu¹, Yuanli Li^{1

2}, Zeming Qi¹, Hui Su¹, Weiren Cheng¹, Wanlin Zhou¹, Hui Zhang¹, Xuan Sun¹, Xiuxiu Zhang¹, Yanzhi Xu¹, Yong Jiang³, Qinghua Liu¹, Shiqiang Wei¹

Affiliations

¹ National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, P. R. China.
² Fundamental Science on Nuclear Wasters and Environmental Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010, Sichuan, P. R. China.
³ Shanghai Synchrotron Radiation Facility, Zhangjiang National Lab, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China.

PMID: 34472867
DOI: 10.1021/acs.jpclett.1c01981

Abstract

We present a strategy of self-nanocavity confinement for substantially boosting the superior electrochemical hydrogen peroxide (H₂O₂) selectivity for conductive metal-organic framework (MOF) materials. By using operando synchrotron radiation X-ray adsorption fine structure and Fourier transform infrared spectroscopy analyses, the dissociation of key *OOH intermediates during the oxygen reduction reaction (ORR) is effectively suppressed over the self-nanocavity-confined X-Ni MOF (X = F, Cl, Br, or I) catalysts, contributing to a favorable two-electron ORR pathway for highly efficient H₂O₂ production. As a result, the as-prepared Br-confined Ni MOF catalyst significantly promotes H₂O₂ selectivity up to 90% in an alkaline solution, evidently outperforming the pristine Ni MOF catalyst (40%). Moreover, a maximal faradic efficiency of 86% with a high cumulative H₂O₂ yield rate of 596 mmol g_catalyst^-1 h^-1 for electrochemical H₂O₂ generation is achieved by the Br-confined Ni MOF catalyst.