Nano–Confinement Construction of FeCo@NCNTs nanocomposite for pH–Universal Oxygen Reduction Catalysis and High–power Zn–air battery

The sluggish kinetics of the oxygen reduction reaction (ORR) pose a critical bottleneck in the energy conversion efficiency of fuel cells and metal–air batteries. Developing non-precious metal catalysts with pH-universal adaptability and high cost-effectiveness is an urgent need in the field. In this study, we introduce an innovative biomass pyrolysis-driven nano-confinement strategy. Expired milk powder and g-C 3 N 4 are utilized as dual-function carbon sources to successfully construct a composite structure of nitrogen-doped carbon nanotubes (NCNTs) encapsulating FeCo alloy nanoparticles (FeCo@NCNT). During high-temperature pyrolysis, the decomposition products of milk powder deposit onto the molten FeCo particles, forming carbon nanotubes, while the decomposition of g-C 3 N 4 provides nitrogen doping and induces periodic distortions in the carbon lattice, resulting in nanoconfined morphology of FeCo@NCNT. This structure formed by N-doped carbon nanotubes encapsulating FeCo alloy enables the catalyst to achieve half-wave potentials of 0.83 V, 0.71 V, and 0.60 V in 0.1 mol·L −1 KOH, 0.5 mol·L −1 H 2 SO 4 , and 0.1 mol·L −1 PBS electrolytes, respectively. The assembled zinc–air battery exhibits an open-circuit voltage of 1.51 V and a peak power density of 169 mW∙cm –2 . This approach provides a new paradigm for biomass waste resource utilization and the design of energy catalysts for pH-universal applications.