Metal‐Free Electrocatalysts for H2O2 Electrosynthesis: From Sites Identification to Electrochemical Advanced Oxidation Process

Carbonaceous materials especially the metal‐free carbons have attracted widespread attentions owing to their risk free with metal dissolving during the electrocatalysis process, but their further developments are still hindered by missing a suitable scenario on practical applications. Herein, we demonstrate a successful case of using the oxygen‐containing‐groups modified carbons for the H2O2 electrosynthesis and the derivate electrochemical advanced oxidation process. The active sites with the more C‐O rather than C=O groups are easily obtained by controlling the temperature and time in the wet chemical treatment. Identified by theoretical calculations and electrochemical testing, the modified carbons with the highest ratio of C‐O/C=O groups exhibit the high activity with the above 90% H2O2 selectivity over the entire potential during 2e‐transfer oxygen reduction reaction, attributing to their enlarged charge delocalization. In addition, the corresponding gas diffusion electrodes with the high‐speed and high‐stability H2O2 electrosynthesis (2.78 μg s‐1 cm‐2 with the above 80% current efficiency) are applied for the electro‐peroxone process on the simulant and practical phenolic wastewater, where the chemical oxygen demand removal reaches above 90%. The long‐term operation in the harsh electrochemical environment for over 200 h also confirms its great potential on practical electrochemical applications.