Cobalt-atom electrocatalytic framework on CO2-derived defective carbon for enhanced H2O2 production across pH levels

The increasing demand for hydrogen peroxide (H2O2) has highlighted the importance of developing sustainable production methods. Electrochemical H2O2 synthesis via the two-electron oxygen reduction reaction (2e− ORR) has gained attention as a promising alternative to the conventional anthraquinone process. This study introduces a cobalt single-atom catalyst supported on oxygen-functionalized defective CO2-derived porous carbon (Co/O-d-CPC) for 2e− ORR. The electronic structure of the cobalt atoms in the molecular catalysts is modulated due to oxygen dopants in the carbon matrix, enabling them to serve as effective active sites for the 2e− ORR. Density functional theory (DFT) calculations and structural characterizations revealed the critical role of specific oxygen functionalities, specifically, triple-coordinated oxygen groups, in optimizing the cobalt single atoms. The synergistic effect between cobalt and these oxygen groups significantly enhanced the 2e− ORR catalytic performance. The electrocatalyst was evaluated under a wide range of pH conditions and demonstrated an average H2O2 selectivity of 93% within the voltage range of 0.2–0.45 V vs. RHE in neutral media, with significant performance improvements also observed in acidic and alkaline electrolytes. Notably, in flow cell tests with neutral electrolytes, Co/O-d-CPC achieved an exceptional H2O2 production rate of 14.4 mol g−1 h−1 at a constant current of 300 mA cm−2.