Cascade protection strategy for anchoring atomic FeN3 sites within defect-rich wood carbon aerogel for high-performance Zn-air batteries and versatile application

• MPWC-FeSA was developed via a multi-substrate cascade protection strategy. • Attaining the dispersion of metal at an atomic level and securely anchoring it to the carbonized wood support. • MPWC-FeSA exhibit remarkable ORR activity in Zn-air batteries. • MPWC-FeSA can be used as a self-supported air cathode without the need for bonding agents or carbon cloths. The emergence of metal-nitrogen-carbon single atom catalysts (M-N-C SACs) has revolutionized the field of cathode materials in zinc-air battery (ZAB) devices. Nevertheless, accurately regulating the metal–carbon support interactions and the metal coordination centers at the atomic scale remains pivotal scientific challenges for enhancing their intrinsic catalytic activity. Besides, the carbon substrate materials commonly in the powder form entail essential dependence on extra binders or carbon cloths, hindering the development of self-supported M-N-C SACs for practical electrochemical devices. In this study, we employed the natural wood and implemented an effective cascade protection strategy to achieve a multi-level porous wood-derived carbon-supported Fe single atom catalyst (MPWC-FeSA) with atomically dispersed Fe-N 3 sites, abundant defects, hierarchical porous network structure, and robust mechanical properties. Density functional theory calculations confirm that vacancy defects improve the electronic environment surrounding the FeN 3 active sites in MPWC-FeSA, resulting in a low overpotential for the oxygen reduction reaction (ORR). The MPWC-FeSA exhibited exceptional ORR performance when utilized in the assembled liquid-state Zinc Air Batteries (LZABs) and quasi-solid-state devices for diverse application scenarios. This study offers novel prospects for transforming wood biomass into the self-supported electrode materials, as well as opens up effective avenues in achieving atomic economy.