Vacancy-Enhanced Sb-N₄ Sites for the Oxygen Reduction Reaction and Zn-Air Battery

With the advantages of a Fenton-inactive characteristic and unique p electrons that can hybridize with O₂ molecules, p-block metal-based single-atom catalysts (SACs) for the oxygen reduction reaction (ORR) have tremendous potential. Nevertheless, their undesirable intrinsic activity caused by the closed d¹⁰ electronic configuration remains a major challenge. Herein, an Sb-based SAC featuring carbon vacancy-enhanced Sb-N₄ active centers, corroborated by the results of high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine structure, has been developed for an incredibly effective ORR. The obtained Sb_SA-N-C demonstrates a positive half-wave potential of 0.905 V and excellent structural stability in alkaline environments. Density functional theory calculations reveal that the carbon vacancies weaken the adsorption between Sb atoms and the OH* intermediate, thus promoting the ORR performance. Practically, the Sb_SA-N-C-based Zn-air batteries achieve impressive outcomes, such as a high power density of 181 mW cm^-2, showing great potential in real-world applications.