Conductive Two-Dimensional Magnesium Metal-Organic Frameworks for High-Efficiency O2 Electroreduction to H2O2

Abstract

Direct electrosynthesis of H2O2 via a two-electron oxygen reduction reaction (2e- ORR) under ambient conditions is emerging as a promising solution toward on-site applications for the replacement of the energy-consuming, waste-intensive, and indirect anthraquinone process. To date, state-of-the-art 2e- ORR catalysis is mostly performed with transition-metal-based materials, while main-group element-based catalysts are much less established, for which there is an urgent need of proper understanding. Herein, we report a conductive two-dimensionally layered Mg3(hexaiminotriphenylene)2 electrocatalyst for selective hydrogenation of O2 to synthesize H2O2 (selectivity >90%) with a robust high catalytic efficiency. In situ spectroscopic monitoring of the catalytic reactions and kinetic studies not only illustrate the reaction mechanisms on Mg3(hexaiminotriphenylene)2 but confirm that the Mg2+ center serving as the real active site is responsible for the critical intermediate OOH* forming event. Additionally, in-depth density functional theory calculations further discuss the excellent activity and selectivity of Mg3(hexaiminotriphenylene)2 for H2O2 production.