Enabling Direct H2O2 Production in Acidic Media through Rational Design of Transition Metal Single Atom Catalyst

The electrochemical oxygen reduction reaction in acidic media offers an attractive route for direct hydrogen peroxide (H2O2) generation and on-site applications. Unfortunately there is still a lack of cost-effective electrocatalysts with high catalytic performance. Here, we theoretically designed and experimentally demonstrated that a cobalt single-atom catalyst (Co SAC) anchored in nitrogen-doped graphene, with optimized adsorption energy of the *OOH intermediate, exhibited a high H2O2 production rate, which even slightly outperformed the state-of-the-art noble-metal-based electrocatalysts. The kinetic current of H2O2 production over Co SAC could reach 1 mA/cmdisk2 at 0.6 V versus reversible hydrogen electrode in 0.1 M HClO4 with H2O2 faraday efficiency > 90%, and these performance measures could be sustained for 10 h without decay. Further kinetic analysis and operando X-ray absorption study combined with density functional theory (DFT) calculation demonstrated that the nitrogen-coordinated single Co atom was the active site and the reaction was rate-limited by the first electron transfer step.