p-Block metal boosted oxygen electrocatalysis of Fe-N-C for alkaline seawater electrolyte-based zinc-air batteries.

Seawater electrolyte-based zinc-air batteries (SZABs) offer advantages such as high theoretical energy density, safety, and environmental friendliness. However, their commercial application is limited by sluggish oxygen reduction reaction (ORR) kinetics and Cl- adsorption-induced corrosion of the catalysts in seawater. Herein, we propose the construction of a typical p-d orbital hybridization structure between p-block and d-block metal atoms, which enables the simultaneous enhancement of ORR kinetics and inhibition of Cl--induced poisoning of the active sites. First, Fe-based p-d orbital hybrid catalysts are screened via theoretical calculations, and FeSn dual single-atom catalysts (FeSn-DSACs) are identified as the optimal choice, attributed to their ideal adsorption free energy profiles for both *OH and Cl-. The resultant FeSn-DSACs demonstrate desirable ORR performance in an alkaline seawater. When assembled into SZABs, they deliver a peak power density of 255.6 mW cm-2 and exhibit stable operation for over 500 h. Theoretical calculations and in-situ characterizations suggest that p-d hybridization in the FeSn-DSACs weakens the strong adsorption energy of traditional Fe sites towards *OH intermediates, while the high electron cloud density of Sn sites in-situ constructs a locally negatively charged interface to inhibit the adsorption and corrosion of Cl-, collectively significantly enhancing the seawater ORR catalytic activity and stability.