Electrospun Trimetallic NiCoCu/CNF Electrocatalyst with Synergistic Electronic Coupling for Enhanced Methanol Electrooxidation

The development of efficient, low-cost electrocatalysts to replace platinum-based materials remains a major challenge for direct methanol fuel cells (DMFCs). In this study, a trimetallic NiCoCu catalyst was prepared on electrospun carbon nanofibers (NiCoCu/CNF) by electrospinning followed by stabilization and carbonization. X-ray diffraction (XRD) analysis revealed an fcc metallic NiCoCu-type crystalline phase, with an average crystallite size of approximately 13.13 nm. Scanning electron microscopy (SEM) showed a continuous, bead-free fibrous morphology with an average fiber diameter of approximately 271 nm, while transmission electron microscopy (TEM) revealed well-dispersed nanoparticles with diameters of approximately 33–98 nm. The electrochemical behavior was evaluated by cyclic voltammetry, linear sweep voltammetry, chronoamperometry, and electrochemical impedance spectroscopy in an alkaline methanol electrolyte. The current density at 0.8 V increased from 21 mA cm−2 for NiCo/CNF to 111 mA cm−2 for NiCoCu/CNF, while the Tafel slope decreased from 248 to 125 mV dec−1. The NiCoCu/CNF electrode also exhibited a charge-transfer resistance of 14.63 Ω at 2 M methanol, the lowest value among the investigated methanol concentrations. The enhanced electrochemical response is associated with the combined effects of the Ni–Co–Cu composition, nanoscale structure, nanoparticle dispersion, and conductive CNF architecture. Overall, NiCoCu/CNF demonstrates promising platinum-free electrocatalytic performance for methanol oxidation under the investigated alkaline three-electrode conditions and merits further evaluation for alkaline DMFC applications.