Constructing Fe single atoms via a novel dual-MOF strategy as highly efficient oxygen reduction/evolution catalyst

The sluggish oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) kinetics at the air cathode impede the performance of zinc-air batteries (ZABs). Although single-atom catalysts obtained from metal-organic frameworks (MOFs) exhibit impressive catalytic activities, metal species tend to aggregate during the pyrolysis, making it difficult to achieve highly dispersed atomic active sites. To address this issue, a dual-MOF strategy was employed to successfully synthesize Fe single-atom catalyst (Fe/NC-920) from ZIF-8@MIL-101(Fe)#20. During the pyrolysis, Zn volatilization from ZIF-8 generated anchoring sites, while Fe atoms from MIL-101(Fe) were stabilized at these sites, forming stable Fe-N 4 coordination. Due to the rich porous structure and the highly dispersed active sites, Fe/NC-920 exhibited superior OER (an overpotential of 310 mV at 10 mA cm −2 ) and ORR (a half-wave potential of 0.90 V) activities. Besides, the ZAB based on Fe/NC-920 demonstrated superior stability than the ZAB based on Pt/C + RuO 2 . This strategy provides a feasible approach for the development of effective ZAB catalysts.