Continuous On-Site H₂O₂ Electrosynthesis via Two-Electron Oxygen Reduction Enabled by an Oxygen-Doped Single-Cobalt Atom Catalyst with Nitrogen Coordination

Single-Co atom catalysts are suggested as an efficientplatinummetal group-free catalyst for promoting the oxygen reduction intowater or hydrogen peroxide, while the relevance of the catalyst structureand selectivity is still ambiguous. Here, we propose a thermal evaporationmethod for modulating the chemical environment of single-Co atom catalystsand unveil the effect on the selectivity and activity. It disclosesthat nitrogen functional groups prefer to proceed the oxygen reductionvia a 4e(-) pathway and notably improve the intrinsicactivity, especially when being coordinated with the Co center, whileoxygen doping tempts the electron delocalization around cobalt sitesand decreases the binding force toward HOO* intermediates, therebyincreasing the 2e(-) selectivity. Consequently, thewell-designed oxygen-doped single-Co atom catalysts with nitrogencoordination deliver an impressive 2e(-) oxygen reductionperformance, approaching the onset potential of 0.78 V vs RHE andselectivity of >90%. As an impressive cathode catalyst of an electrochemicalflow cell, it generates H2O2 at a rate of 880mmol g(cat) (-1) h(-1) andfaradaic efficiency of 95.2%, in combination with an efficient nickel-ironoxygen evolution anode.