Asymmetric high-coordination Co-NSP single-atom catalysts with tailored d-p-orbital electron structure for efficient bifunctional catalyst of rechargeable Zn-air battery cathodes

Precise manipulation of the multiple heteroatoms coordination environment is crucial to maximize the catalytic performance of single atoms catalysts (SACs). However, the mechanisms regulating the relationship between the coordination environment and catalytic performance remain inadequately validated. Here, we synthesized a N,P,S co-coordinated hollow porous single-atom cobalt catalyst (Co-NSP-HPC) and proposed a facile strategy to fine-tune the first coordination shell to construct asymmetric high-coordination structures. Co-NSP-HPC exhibits a higher half-wave potential (0.898 V) and enhanced kinetic current density (33 mA cm−2), outperforming commercial Pt/C catalysts. Theoretical calculations indicate that the interaction between the first coordination shell (N3S) and axial P leads to robust, well-distributed Co sites with optimized electronic structures, promoting d-p orbital hybridization between Co and O atoms and the negative shift of the d-band center, which optimizes the adsorption free energy of oxygen reduction reaction (ORR) intermediates. Furthermore, the hollow porous structure modulates the local environment, effectively exposing active sites and enhancing ORR kinetics. Zinc-air batteries (ZABs) based on Co-NSP-HPC cathodes exhibit high and stable open-circuit voltages (1.49 V) and maximum power densities (183.07 mW cm−2). This work will enrich the design philosophy of modulating the coordination environment of electrocatalysts for advanced Zinc-air batteries and beyond. [Display omitted] •Synthesis of uniform hollow Co-NSP via one-step pyrolysis that preserves morphology during multi-heteroatom coordination.•Systematically investigate the impact of different coordination environments on single-atom catalyst performance.•The P, S coordination enhances the hybridization of the d-p orbital between the single Co atoms and the O atoms.•Zn-air batteries with Co-NSP-HPC cathodes show maximum power density (183.07 mW cm−2).