Orbital Stabilization in Sb-Based Single-Atom Catalyst

The construction of cathode catalysts that combine high activity and stability is essential for improving the energy conversion efficiency of metal-air batteries and fuel cells. Single-atom catalysts (SACs) provide a novel solution to the challenge of slow oxygen reduction reaction (ORR) kinetics by atomic-level active sites and precisely tunable electronic configurations. Unlike transition metals, the relatively inert Sb centers can be precisely tuned by coordination engineering to exhibit strong affinity. However, the strength of the Sb-N bond is a fundamental determinant of stability. This new study, led by Professor We Zhang in the School of Materials Science and Engineering, has successfully achieved precise tuning of the first coordination shell environment of Sb centres in Sb_AC-NC-x catalysts after varying degrees of NH₄Cl gas-phase etching. Remarkably, the catalyst with an encapsulated SbN₅ stereoconfiguration exhibited an extremely high half-wave potential (E_1/2 = 0.908 V) in an alkaline medium, and the E_1/2 decreased by only 11 mV after accelerated durability tests (150,000 cycles), which demonstrated that the catalyst possessed excellent long-term durability. Combining in-situ techniques and theoretical calculations, they fully verified that the orbital stabilisation effect of the SbN₅ stereoconfiguration mitigated the *OH steric hindrance on the Sb centres. This phenomenon promoted the activation of the *OH state by preventing the interaction between the Sb centres and intermediates, thus accelerating the formation of *OOH. This study was supported by the National Natural Science Foundation of China.