P-Orbital Bismuth Single-Atom Catalyst for Highly Effective Oxygen Electroreduction in Quasi-Solid Zinc-Air Batteries

P-block metals have gradually been utilized to synthesize non-noble-metal catalysts for oxygen reduction reaction (ORR) due to the easily tunable localized p-orbitals and resulted versatile electronic structures. The high-density single-atom bismuth sites (Bi-NC) anchored onto nitrogen-doped three-dimensional porous carbon are proved to possess significant electrocatalytic ORR performance. Theoretical calculations unveil positively charged bismuth centers prominently improved the adsorption capacity of N-doped carbon to O₂ . The p orbitals of Bi sites within Bi-NC easily generate hybrid states with p orbitals of O₂ , thus promoting charge transfer and ultimately reducing the energy barrier of ORR. Benefiting from p-orbital electrons regulation of bismuth atoms, Bi-NC exhibit ORR half-wave potential of 0.86 V (vs RHE). Additionally, both liquid and quasi-solid zinc-air batteries with Bi-NC as air-cathodes achieve higher power density and specific capacity than 20 wt% Pt/C, and comparable stability and round-trip efficiency with 20 wt% Pt/C. The discovery sheds light on the theoretical and practical guidance for p-block metallic single-atom catalysts.