Boosting acidic hydrogen peroxide electrosynthesis on 2D metal-organic framework nanosheets based on cobalt porphyrins

Abstract

The 2-electron electrocatalytic oxygen reduction reaction (2e⁻ ORR) to hydrogen peroxide (H₂O₂) represents a promising strategy to resolve the high energy consumption and increasing environmental concerns inherent in the traditional anthraquinone process. The acidic 2e⁻ ORR has emerged as an exciting alternative for industrial-level H₂O₂ production, whereas is hampered by the inferior H₂O₂ selectivity due to the uncontrollable proton-coupled electron transfer processes in an acidic environment. Herein, an ultrathin 2D metal–organic frameworks (MOFs) nanosheet based on cobalt tetra(4-carboxyphenyl) porphine (Co-TCPP NSs) is designed to promote H₂O₂ selectivity up to 96.5 %, accompanied with a remarkable H₂O₂ generation rate of 4677.42 mg·L⁻¹·h⁻¹. Of note, the Co-TCPP NSs also demonstrate its potential for the electro-Fenton process with a cumulative H₂O₂ concentration of 1.21 wt%, highlighting its practical potential in portable H₂O₂ generation electrochemical devices for distributed applications. Our findings demonstrated that the efficient H₂O₂ electrosynthesis could be attributed to the attenuated *OOH adsorption over Co-N₄ moiety on the Co-TCPP NSs, which consequently suppresses its further reduction to form H₂O. This work highlights the potential of 2D MOF architecture for the 2e⁻ ORR and provides an atomic-level insight into the enhanced H₂O₂ selectivity.