Structural Modulation of Covalent Organic Frameworks for Efficient Hydrogen Peroxide Electrocatalysis

Abstract

The electrochemical production of hydrogen peroxide (H2O2) via metal-free catalysts has garnered attention as a viable and sustainable alternative to the conventional anthraquinone process. The precise architectural design of these electrocatalysts poses a significant challenge, requiring intricate structural engineering to optimize the electron transfer during the oxygen reduction reaction (ORR). Herein, our study introduces a novel design of covalent organic frameworks (COFs) that effectively shift the ORR from a four-electron to a more advantageous two-electron pathway. Notably, the JUC-660 COF, with strategically charge-modified benzyl moieties, achieved a continuous high H2O2 yield of over 1200 mmol g-1 h-1 for an impressive more than 85 hours duration in a flow cell setting, marking it as one of the most efficient metal-free and non-pyrolyzed H2O2 electrocatalysts to be reported. Theoretical computations alongside in-situ infrared spectroscopy indicated that JUC-660 markedly diminishes the adsorption of the OOH* intermediate, thereby steering the ORR towards a desired pathway. Furthermore, the versatility of JUC-660 was showcased through its application in the electro-Fenton reaction, where it efficiently and rapidly removed aqueous contaminants. This work delineates a pioneering approach to altering the ORR pathway, ultimately paving the way for the development of highly effective metal-free H2O2 electrocatalysts.