Atomic Engineering Modulates Oxygen Reduction of Hollow Carbon Matrix Confined Single Metal‐Nitrogen Sites for Zinc‐Air Batteries

Abstract The systematical understanding of metal‐dependent activity in electrocatalyzing oxygen reduction reaction (ORR), a vital reaction with sluggish kinetics for zinc‐air batteries, remains quite unclear. An atomic and spatial engineering modulating ORR activity over hollow carbon quasi‐sphere (HCS) confined in a series of single M‐N (M = Cu, Mn, Ni) sites is reported here. Based on the theoretical prediction and experimental validation, Cu‐N 4 site with the lowest overpotential shows a better ORR kinetics than Mn‐N 4 and Ni‐N 4 . The ORR activity of single‐atom Cu center can be further improved by decreasing the coordination number of N to two, namely Cu‐N 2 , due to the enhancement of electrons with lower coordination structure. Benefitting from the unique spatial confinement effect of the HCS structure in modulating electronic feature of active sites, the Cu‐N 2 site confined in HCS also delivers highly improved ORR kinetics and activity relative to that on planner graphene. Additionally, the best catalyst holds excellent promise in the application of zinc‐air batteries. The findings will pave a new way to atomically and electronically tune active sites with high efficiency for other single‐atom catalysts.