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 ofH₂O₂ production over Co SAC could reach 1 mA=cm²_disk 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.  © 2019 Published by Elsevier Inc.