Highly Efficient Metal-Free Coal-Based Carbon Aerogel Catalyst for Oxygen Reduction to Produce Hydrogen Peroxide

Abstract

In this study, a highly efficient metal-free catalyst derived supported on coal-based carbon aerogel was successfully synthesized for the two-electron transfer oxygen reduction reaction (2e^– ORR) to produce hydrogen peroxide (H₂O₂). The catalyst, with its high specific surface area and hierarchical porous structure, demonstrated exceptional selectivity for H₂O₂ under alkaline conditions. By optimization of the synthesis and drying conditions, particularly through the use of supercritical drying technology, the physicochemical properties and selectivity of the catalyst were significantly enhanced. Notably, the coal-based carbon gel obtained through supercritical drying with CO₂ exhibited the superior specific surface area over 1311 m²·g^–1. The H₂O₂ selectivity over 95% at a potential of 0.5 V vs SHE was obtained using the catalyst material synthesized from this study. It was also revealed that the high selectivity was attributed to the layered edge active sites, which are rich in carbonyl (C=O) and carboxyl (COOH) groups. In situ FTIR and Raman spectroscopic analyses confirmed the two-electron-transfer ORR reaction mechanism from this study.