Highly efficient electrosynthesis of hydrogen peroxide through reversible transformation between catechol and o-benzoquinone on polydopamine modified carbon black

[Display omitted] •Transformation between catechol and o-benzoquinone on polydopamine promoted 2e−-ORR.•Polydopamine-modified carbon black improved H2O2 selectivity from 75.5 % to 97.0 %.•The gas diffusion system utilized the oxygen from nature air without extra aeration.•A rapid disinfection efficiency of 8 log cells was achieved in 10 min. Carbon-based materials are more promising catalysts for H2O2 electrochemical production. However, the common method for modifying carbon-based materials is surface functionalization with harsh and uncontrollable reaction conditions, hindering the precise regulation of the active sites. Herein, we proposed a carbon-based material modified by polydopamine (CB-PDA) that was easily prepared and used in air diffusion electrode system for H2O2 production. The rapid and reversible transformation between catechol and o-benzoquinone on PDA could improve the H2O2 selectivity from 75.5 % to 97.0 % during the electrocatalytic process. The detection of adsorbed *HOOH and *OOH in oxygen reduction reaction proved the preference of CB-PDA for the two-electron pathway. The H2O2 formation rate constant of CB-PDA increased significantly from 25.85 to 60.82 mM h−1. The highest cumulative H2O2 concentration could reach 10200 mg L−1 in 9 h. Long-term operation tests proved the good operational stability. Furthermore, this system was cost-effective without additional aeration energy consumption and could achieve rapid disinfection in 10 min, which would have great potential to be used in environmental remediation.