Tuning Proton Affinity on Co−N−C Atomic Interface to Disentangle Activity‐Selectivity Trade‐off in Acidic Oxygen Reduction to H 2 O 2

Abstract In oxygen reduction reaction to H 2 O 2 via two‐electron pathway (2e − ORR), adsorption strength of oxygen‐containing intermediates determines both catalytic activity and selectivity. However, it also causes activity‐selectivity trade‐off. Herein, we propose a novel strategy through modulating the interaction between protons and *OOH intermediates to break the activity‐selectivity trade‐off for highly active and selective 2e − ORR. Taking the typical cobalt–nitrogen–carbon single‐atom catalyst as an example, boron heteroatoms doped into second coordination sphere of CoN 4 (Co 1 ‐NBC) increase proton affinity on catalyst surface, facilitating proton attack on the former oxygen of *OOH and thereby promoting H 2 O 2 formation. As a result, Co 1 ‐NBC simultaneously achieves prominent 2e − ORR activity and selectivity in acid with onset potential of 0.724 V vs . RHE and H 2 O 2 selectivity of 94 %, surpassing most reported catalysts. Furthermore, Co 1 ‐NBC exhibits a remarkable H 2 O 2 productivity of 202.7 mg cm −2 h −1 and a remarkable stability of 60 h at 200 mA cm −2 in flow cell. This work provides new insights into resolving activity‐selectivity trade‐off in electrocatalysis.