Fine Engineering of d-Orbital Vacancies of ZnN4 via High-Shell Metal and Nonmetal Single-Atoms for Efficient and Poisoning-Resistant ORR

Atomically dispersed metal–nitrogen–carbon (M–N–C) materials are active oxygen reduction reaction (ORR) catalysts. Among M–N–C catalysts, ZnN4 single-atom catalysts (SACs) due to a nearly full 3d10 electronic configuration insufficiently activate oxygen and display low ORR activity. To finely engineer d-orbital vacancies of ZnN4, we combine high-shell metal and nonmetal SAs as electronic regulators that are ZnN4Cl and carbon vacancy-hosted −Cl motifs, which show complementary electron-withdrawing capacities versus the ZnN4. Under that, the ZnN4 exhibits significantly enhanced ORR activity with a half-wave potential (E1/2) of 0.912 VRHE relative to the unmodified ZnN4 (E1/2 = 0.822 VRHE) and simultaneously robust durability (negligible activity loss after 10,000 potential cycles). Particularly, the engineered ZnN4 possesses high resistance to SCN– poisoning, which is rarely achieved among M–N–C SACs. Our works show that combining high-shell metal and nonmetal SAs can finely engineer d-orbital vacancies of metal centers to an optimal state, thereby intrinsically enhancing their catalytic performance.