Synergistic cooperation between atomically dispersed Zn and Fe on porous nitrogen-doped carbon for boosting oxygen reduction reaction

A dual-atom catalyst (Zn/Fe-NC) is synthesized through pyrolyzing polyvinylpyrrolidone (PVP) coated on Fe-doped ZIF-8. Benefiting from a proper architecture and a synergistic effect between Zn and Fe sites, the Zn/Fe-NC catalyst provides an outstanding oxygen reduction reaction (ORR) activity, featuring a high half-wave (E1/2) of 0.875 V versus reversible hydrogen electrode (RHE), excellent long-term stability with a negligible shift of E1/2 (8 mV) after 10,000 cycles, and notable resistance to methanol in alkaline media. Density functional theory (DFT) calculation showed that the overpotential of ORR catalyzed by Zn/Fe-NC is only 0.282 V, and a slightly down-shifted d band center of active Fe affected by Zn significantly alleviates the adsorption of OH* intermediates, thus promoting the overall ORR electrocatalytic activity. Moreover, zinc-air batteries (ZABs) with Zn/Fe-NC catalyst as oxygen cathode display remarkable power density (186 mW cm−2) and specific capacity (815 mAh g−1), demonstrating great prospects for practical applications.