Lithium-oxygen batteries (LOBs) are renowned for their ultrahigh theoretical energy densities. However, their practical applications are significantly limited by sluggish oxidation kinetics and elevated charge overpotentials. Most single-atom catalysts (SACs) utilized in LOBs are predominantly based on transition metals, which feature unsaturated d-orbital coordination. In contrast, the rare-earth element samarium (Sm) possesses a rich array of 4f-orbital electrons. Recent studies have demonstrated that Sm SACs can effectively enhance the conversion of polysulfides in lithium-sulfur batteries (LSBs) and achieve remarkable cycling stability in full-cell experiments. Inspired by the work, we systematically design and optimize 17 configurations of Sm SACs for LOBs by using first-principles calculations, which are denoted as SmNxCy (x + y = 4 or 6). Through comprehensive screening for stability and catalytic activity, we identify the SmN3C3-1 catalyst as an optimal candidate for LOBs. The catalytic mechanism of the SmN3C3-1 SAC over the oxygen evolution reaction of the Li2O2 molecule is investigated. The Gibbs free energy of the two-electron dissociation process indicates that the second step of the reaction is the rate-determining step (RDS). At the equilibrium potential, the charge overpotential is 0.52 V. Furthermore, mechanistic analysis reveals that the d-f-p orbital hybridization in SmN3C3-1 effectivelyreduces the shielding effect on the Sm 4f orbitals, facilitates interfacial charge transfer, and significantly improves the catalytic performance of the Li2O2 oxidation. This study provides novel insights into the potential of rare-earth-based SACs for improving the performance of LOBs.
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