Enhanced catalytic performance of CoN4 single atom catalysts by engineering the first coordination spheres

Abstract

Single-atom catalysts (SACs) exhibit significant potential as high-efficiency catalysts with enhanced energy density in aprotic Li-O₂ battery. In this study, we investigated the influence of the coordination environment of CoN₄ SACs on the electrochemical performance of Li-O₂ battery using density functional theory (DFT) calculations. Our findings indicate that CoN₄ SACs preferentially adsorb O₂, while C-coordinated CoN_4-xC_x (x = 1–4) SACs demonstrate a tendency to adsorb Li in the initial step of the reaction. The computed Gibbs free energies for each reaction step suggest that CoN_4-xC_x (x = 0–4) SACs are promising candidates for cathode electrocatalysts in Li-O₂ batteries. Notably, the calculated overpotentials for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) reveal that CoN₃C (η_ORR/η_OER = 0.14/0.23 V) and CoNC₃ (η_ORR/η_OER = 0.22/0.14 V) SACs exhibit significantly low values, highlighting their potential as high-performance cathode electrocatalysts. Additionally, the adsorption free energy of *Li₃O₂ serves as a simple activity descriptor for CoN_4-xC_x (x = 0–4) SACs. These insights suggest that CoN_4-xC_x (x = 0–4) SACs may have promising applications in facilitating efficient ORR and/or OER, providing guidance for the design of advanced aprotic Li-O₂ batteries.