Bimetal Organic Framework Derived CoM@N-C Composites As Bifunctional Oxygen Catalysts for Zn-air Batteries

Metal-loaded nitrogen-doped carbon (M@N-C) catalysts have shown promise as electrocatalysts for replacing noble metal catalysts in industrial processes. To study the influence on structural and performance caused by different bimetal doping, a family of bimetals CoM@N-C (M=Cu/Ni/Fe) composites with porous surface and abundant C defects were well-designed. After bimetallic doping, more defects are introduced into the carbon frameworks, and the Metal-N species are fixed. As such, efficient utilization of active sites and rapid mass transfer make the reaction kinetics process more favorable and stable. Density functional theory (DFT) calculations indicate that Cu/Ni doping optimizes the electronic environment of the Co-N, resulting in the balanced adsorption and dissociation of oxygen intermediates. While the synergy of FeCo activates the O=O, which promotes the sharp decrease in free energy of *OOH to *O, shifting the rate-determining step for ORR. This indicates the adsorption site transfer of CoFe0.05@N-C in oxygen reduction and oxygen evolution reactions. The CoFe0.05@N-C catalyst exhibits superior bifunctional catalytic activity than that of Pt catalysts (E1/2=0.85V, Ej=10=1.65V). This work presents a simple strategy to fabricate well-defined bimetals doping in bifunctional oxygen electrocatalysts and it is expected to inspire future work on the role of electronic structure modulation and interface engineering.