NiCu alloy-modified N-doped carbon nanofiber networks for efficient ammonia electrooxidation

Developing earth-abundant electrocatalysts for the sluggish ammonia oxidation reaction (AOR) is critical for sustainable ammonia energy utilization and wastewater treatment. Herein, three-dimensionally interconnected N-doped carbon nanofiber-supported NiCu alloy electrocatalysts are synthesized via electrospinning and pyrolysis using ZIF-8 as the nitrogen source. The structure-activity relationship toward the AOR is investigated by adjusting the ZIF-8 dosage and Ni/Cu molar ratio. The optimized Ni₃Cu₁/N-CNFs-200 catalyst (200 mg ZIF-8, Ni/Cu = 3 : 1) achieves improved AOR activity, with an onset potential of 0.45 V vs. Hg/HgO and a 5.2-fold larger electrochemically active surface area (ECSA) than the ZIF-8-free control catalyst. Electrochemical analyses indicate that N doping enlarges the electrochemically active surface area and promotes surface reconstruction toward active oxyhydroxide species, thereby enhancing the catalytic activity. These results demonstrate a geometric-effect-dominated enhancement strategy for non-noble metal AOR electrocatalysts via MOF-derived nitrogen doping, offering insights into the rational design of high-surface-area catalyst supports.