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
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 gcatalyst–1 h–1 for electrochemical H2O2 generation is achieved by the Br-confined Ni MOF catalyst.