Optimizing the electronic structure of carbon-based NiFe nanoparticles via a vanadium mediated strategy for efficient oxygen reduction catalysts in Zn–air batteries†

To improve the catalytic activity of oxygen reduction reaction (ORR) catalysts, optimizing their electronic structure for active sites to reduce electrochemical reaction energy barriers is an effective strategy. Herein, we fabricated vanadium (V)-doped NiFe alloy NPs embedded in an N-doped carbon matrix (V-NiFe@NC) as an electrocatalyst through a Joule heating-assisted MOF derived route. The resulting catalyst exhibits good ORR activity (E_1/2 = 0.882 V) and stability, better than its undoped counterpart (NiFe@NC) and commercial Pt/C, confirming the effectiveness of V-doping in enhancing catalytic activity. Electrochemical tests disclose the enhanced intrinsic catalytic activity and kinetic process of V-NiFe@NC, benefiting from its optimized electronic configuration regulated by the incorporation of V atoms. Meanwhile, DFT calculations reveal that the outer N-carbon layer, serving as the primary active site, can be effectively activated by the V-doped NiFe substrate in V-NiFe@NC, thereby reducing the ORR energy barrier and boosting its catalytic activity. This electrocatalyst further demonstrates high peak power densities (178.8 mW cm⁻²), specific capacity and durability in alkaline Zn–air batteries, indicating its practicality in electrochemical energy conversion devices.