Constructing Fe single-atoms decorated by carbon-coated FeCo ultrathin nanoparticles as high-efficient ORR/OER...

Single-atom catalysts have attracted extensive attention for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) because of their notable advantages. However, despite their high atomic utilization efficiency, these catalysts often suffer from limited activity and inadequate stability, highlighting the need for strategies to enhance their performance. In this work, Fe single atoms decorated by carbon-coated FeCo ultrathin nanoparticles (FeCo/Fe-NC) were fabricated by pyrolyzing the ZnCoFe-ZIF precursor. The introduction of FeCo alloy nanoparticles effectively tuned the electronic structure of Fe single atoms, enabling the optimal adsorption of oxygen intermediates. Furthermore, the hierarchical pore architectures and diverse nitrogen configurations improved the active site exposure and facilitated the mass transport. As a result, FeCo/Fe-NC exhibited outstanding bifunctional performance, with a high half-wave potential of 0.91 V for ORR and a low overpotential of 344 mV at 10 mA cm^-2 for OER, surpassing the commercial catalyst benchmarks. In Zn-air battery (ZAB) test, the catalyst delivered a high open-circuit voltage of 1.485 V, a superior power density of 185.8 mW cm^-2, an excellent specific capacity of 806.6 mAh g^-1, and stable cycling about 800 h. These results demonstrated the potential of FeCo/Fe-NC as a highly efficient bifunctional ORR/OER catalyst for ZAB applications.