Photo-coupled electrocatalytic oxygen reduction to hydrogen peroxide using metal-free CNT-threaded oxidized g-C3N4

Abstract

Hydrogen peroxide (H2O2) has been widely used in environmental cleaning, hospital disinfecting and chemical engineering. Compared to the traditional anthraquinone oxidation method, the electrocatalytic two-electron oxygen reduction reaction (2e-ORR) to produce H2O2 has become a promising alternative due to its green, safety and reliability. However, its industrial application is still limited by the slow reaction kinetics and low selectivity due to the competitive reaction of the 4e-ORR to H2O. Herein, we prepare a novel photoresponsive metal-free electrocatalyst based on oxidized g-C3N4/carbon nanotubes (OCN/CNTs) and introduce an external light field to realize the high-performance electrocatalytic 2e-ORR to produce H2O2. Impressively, the OCN/CNT electrocatalyst exhibits an outstanding H2O2 productivity of 30.7 mmol/gcat/h with a high faradaic H2O2 efficiency of 95%. The oxygen-containing groups of the OCN/CNTs promote the adsorption of oxygen intermediates and the photo-coupled electrocatalysis simultaneously improves the electron transport efficiency and enhances the electrocatalytic selectivity.