Lattice confined Ru single sites in hollow Co₉S₈ polyhedron triggering Co-S-Ru catalytic centers for rechargeable Zn-air battery

Single-atom catalysts with precise structure and tunable coordination nature provide opportunities for developing novel catalytic centers and understanding reaction mechanisms. Herein, hollow Co₉S₈ polyhedrons with lattice-confined Ru single atoms (Ru-Co₉S₈) are fabricated. Aberration-corrected scanning transmission electron microscopy and X-ray absorption spectroscopy verify the isolated Ru atoms are confined in Co₉S₈ to form Co-S-Ru catalytic centers. Theoretical calculations indicate that the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) energy barriers are extensively reduced, and the d-band center of Co₉S₈ downshifts from the Fermi level, therefore boosting the desorption of O-containing intermediates. Consequently, the Ru-Co₉S₈ exhibits an ultralow overpotential of 163 mV at 10 mA·cm⁻² for OER and could catalyze a rechargeable Zn-air battery with a high-power density of 92.0 mW·cm⁻². This work provides a promising approach for designing novel bifunctional catalytic active centers for energy conversion.