Breaking Trade-Off between Selectivity and Activity of 2e – ORR to Boost Hydrogen Peroxide Production and In Situ Utilization for Water Treatment

The electrochemical 2e– oxygen reduction reaction (ORR) offers a promising pathway for on-site hydrogen peroxide (H2O2) production as an alternative to the anthraquinone process. However, challenges remain for low selectivity and a trade-off between selectivity and activity (TOSA). This study develops a novel thermodynamic regulation strategy to improve the selectivity toward 2e– ORR by suppressing competitive 4e– ORR. With the decoupled decisive factors, the selectivity and activity of 2e– ORR can be independently tuned to boost H2O2 production aiming to break the TOSA. Based on density functional theory predictions and experimental validations, a vanadium single atom electrocatalyst with an axially coordinated −NO2 ligand exhibits 98.06% selectivity toward 2e– ORR while the activity approaches the theoretical limit. The H2O2 yield rate reaches up to 7.47 mol gcat–1 h–1 in a neutral electrolyte at 0.30 V vs RHE in a flow cell. Moreover, on-site production and in situ utilization of H2O2 for degrading typical recalcitrant organic pollutants are demonstrated in a dual-cathode electron–Fenton system. Tetracycline and phenol (20 mg L–1) can be degraded with an efficiency up to 100% in 120 min. This study provides a proof-of-concept demonstration of a thermodynamic regulation strategy to promote H2O2 production by addressing low selectivity and TOSA of 2e– ORR, and on-site production and in situ utilization of H2O2 have broader implications in environmental scenarios.