Direct cathodic polarization preparation of ambient CO2-derived oxygen-functionalized carbons for electro-production of H2O2

Electro-generation hydrogen peroxide (H 2 O 2 ) via a two-electron oxygen reduction reaction (2e - ORR) is an effective and feasible strategy for industrial H 2 O 2 production and will likely supersede the traditional anthraquinone oxidation method. However, maintaining high 2e - ORR performance at a wide voltage window and directly identifying real active sites on carbon catalyst surfaces are still challenging. Herein, we propose a method involving the cathodic polarization reduction of ambient CO 2 to control the oxygen functional groups (OFGs) and edge defects on mesoporous and 3D-ordered carbon catalysts (oxygen-functionalized carbons, OFCs). Chemical titrations confirmed that the -COOH species are the most active sites, and in-situ Raman uncovered that edge defects can also act as the active sites for 2e - ORR. The optimized OFC650 with primary -COOH groups and rational defects exhibit the highest selectivity of 94.5 %, a wide voltage window of 0.2–0.75 V vs. RHE (V RHE ) for high H 2 O 2 selectivity, and an enhanced H 2 O 2 production rate of 141.1 mmol g catalyst −1 h −1 cm −2 , outperforming many reported carbons. Oxygen-functionalized carbon prepared from ambient CO 2 achieved 94.5 % H 2 O 2 selectivity with a wide potential window of 0.2–0.75 V RHE . Chemical titration, in-situ Raman, and DFT identified COOH at graphene edge defects as the primary active site for 2e - ORR. • In-situ conversion of CO 2 to oxygen-functionalized carbon. • The oxygen and defects are regulated by varying polarization temperatures. • -COOH and edge defects in OFCs confirmed as active sites via chemical titration and in-situ Raman. • DFT shows -COOH on defected graphene basal plane excels in 2e ORR.