Surface oxygen coverage-mediated *OOH modulation enables highly selective H2O2 electrosynthesis

The electrochemical synthesis of hydrogen peroxide (H 2 O 2 ) suffers from low selectivity toward the 2e − oxygen reduction reaction (ORR) pathway over the competing 4e − pathway. The key to this selectivity lies in precisely controlling the adsorption strength of the critical intermediate *OOH. In this work, we address this challenge through a local micro-environment engineering approach that modulates the surface coverage of active oxygen species (*O) to optimize *OOH adsorption behavior through cobalt-doped zinc oxide catalyst post-treated by ozone (Co-ZnO-O 3 ). The incorporation of Co improves the ratio of oxygen vacancies and enhances the concentration of *O from 28.1 % in pristine ZnO to 39.4 %, and then ozone treatment further increases the surface *O concentration to 52.6 %. The regulatory mechanism via ozone activation on the *O concentration of ZnO and Co-ZnO and further demonstrate that high *O concentration is more favorable for the 2e − ORR. As a result, Co-ZnO-O 3 achieves a remarkable H 2 O 2 selectivity of up to 96 % due to the moderate *OOH adsorption determined optimized by Co-doping and ozone activation. A flow-cell electrolyzer equipped with Co-ZnO-O 3 can deliver an industrial-scale current density of over 300 mA cm −2 at 0.2 V and a record-high H 2 O 2 yield rate of 58.56 mol g −1  h −1 , maintaining a Faradaic efficiency of over 90 % for 50 h. Furthermore, its practical applicability is demonstrated in the degradation of organic pollutants, such as methylene blue and rhodamine B, highlighting its potential application in various fields.