Polyacrylonitrile nanofibers with hollow NiCu, Ni, and Cu nanospheres: Boosting electrocatalysis via enhanced interfacial charge transport and storage

Multifunctional catalytic materials combining polymers with nanoparticles (NPs) lie in advancing their long-term stability, scalability, and predictable performance under real-world operating conditions. In this study, polyacrylonitrile (PAN) nanofibers loaded with hollow nickel (Ni), copper (Cu), and nickel–copper (NiCu) nanoparticles were fabricated. X-ray diffraction confirmed crystalline metal phases in the amorphous PAN matrix while indicating that ∼25 % of Cu as CuO. Spectroscopic analysis revealed alterations in the nitrile and aliphatic stretching bands resulting from NP incorporation. Cu/PAN exhibited a more than twofold increase in the –C–H to –C≡N bond area, attributed to oxygen-containing functional groups from CuO formation. UV–Vis spectra demonstrated tunable absorbance: NiCu/PAN exhibited the broadest and most intense absorption across 250–500 nm, reflecting strong plasmonic coupling between alloyed particles. Electron microscopy illustrated uniform dispersion of NPs on PAN surface, with all three nanofibers showing continuous and bead-free morphology, while NiCu composites displayed reduced NP agglomeration compared to monometallic counterparts. Electrochemical impedance spectroscopy in 0.1 M LiClO4/ACN highlighted that NiCu/PAN possessed the lowest charge transfer resistance (Rct ≈ 9.13 × 102 Ω cm2) and highest double-layer capacitance (Cdl ≈ 43.6 μF cm−2), surpassing Ni/PAN and Cu/PAN analogues. Furthermore, the smallest overpotential at 1 mA cm−2 (−197 mV) and Tafel curve (∼286 mV dec−1) were obtained for NiCu/PAN in 1 M KOH. The main objective of this research was to demonstrate that bimetallic interactions in hollow NiCu particles synergistically enhance interfacial charge transport and storage, thereby showing how metal composition and PAN nanofiber integration can optimize polymer-based nanocomposites for energy and environmental applications.