Single-atom palladium anchored N-doped carbon towards oxygen electrocatalysis for rechargeable Zn–air batteries

Abstract

Herein, an atomically dispersed palladium catalyst on a hierarchical porous structure of N-doped carbon (Pd₁/N–C) is prepared using a facile freeze-drying-assisted strategy. Freeze-drying methods not only suppress the aggregation of Pd atoms but also successfully produce abundant nanopores. HAADF-STEM confirms that Pd single atoms are uniformly anchored on the N–C surface. The Pd₁/N–C electrocatalyst enhances the ORR and OER activity and durability compared to N–C and Pd–NPs/N–C. Rechargeable Zn–air batteries (ZABs) based on novel Pd₁/N–C exhibit a peak power density of 113.7 mW cm⁻² and maintain a voltage efficiency of 64.0% after 495 cycles at a discharge current density of 5 mA cm⁻². Besides, two ZABs in series can supply an LED light for at least 170 h.