Conversion of CO2 to defective porous carbons in one electro-redox cycle for boosting electrocatalytic H2O2 production

Conversion of CO2 to catalytically active carbons for electrochemical synthesis of hydroxide peroxide (H2O2) is highly desirable to replace the energy-intensive anthraquinone process, and achieve carbon utilization and emission reduction. Here, we develop an electrochemical reduction-reoxidation strategy in the in-situ conversion of absorbed CO2 to defective porous carbons (DPCs) for boosting H2O2 production. By rationally varying oxidation conditions, hole and edge defects were controllably created on CO2-derived carbons. Moreover, the defects dramatically enhanced the activity and selectivity toward the 2e- oxygen reduction reaction (ORR). DPC0.5–5 obtained by electro-oxidizing the CO2-derived carbon has edge and hole defects, delivering the H2O2 selectivity greater than 90%. By means of density functional theory calculations, the essential role of defects is demonstrated, and the types of defects with high activity are identified. The approach presented here not only sheds light on the value-added utilization of CO2, but also develops the defect engineering of carbon materials. [Display omitted] Defective carbon catalysts are in-situ synthesized from CO23-/CO2(absorbed) in one electro-redox cycle. Through the synergistic process of electrochemical and chemical reactions, a CO2 cycle is realized. Moreover, the defect densities can be reasonably controlled by the reoxidation time, and the as-obtained defects demonstrate high activity towards the 2e- ORR. •An electrochemical reduction-reoxidation method was used for in-situ conversion of CO2 to defective porous carbons (DPCs).•The defect densities can be controlled by rationally varying reoxidation conditions.•The edge and hole defects in DPCs enhanced both adsorption and activation of O2 molecules.•Theoretical calculations revealed the role of defects and the types of defects with high activity.