Tuning proton affinity on Co–N–C atomic interface to disentangle activity‐selectivity trade‐off in acidic oxygen reduction to H2O2

Abstract

In oxygen reduction reaction to H2O2via 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 CoN4 (Co1‐NBC) increase proton affinity on catalyst surface, facilitating proton attack on the former oxygen of *OOH and thereby promoting H2O2 formation. As a result, Co1‐NBC simultaneously achieves prominent 2e‐ ORR activity and selectivity in acid with onset potential of 0.724 V vs. RHE and H2O2 selectivity of 94%, surpassing most reported catalysts. Furthermore, Co1‐NBC exhibits a record‐high H2O2 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.