Controlled synthesis of FeNi colloidal nanoparticles over NiO/Fe2O3 matrix for the catalytic reduction of 4-nitrophenol

Abstract

This study reports the controlled synthesis of ultrafine FeNi colloidal nanoparticles (2–5 nm) uniformly dispersed over a NiO/Fe₂O₃ matrix, developed as an efficient nanocatalyst for the reduction of 4-nitrophenol to 4-aminophenol. Comprehensive characterization was performed using XRD (X-ray diffraction), FTIR (Fourier transform infrared spectroscopy), UV-Vis DRS (ultraviolet-visible diffuse reflectance spectroscopy), HRTEM (high-resolution transmission electron microscopy), and XPS (X-ray photoelectron spectroscopy). XRD and FTIR confirmed the coexistence of α-Fe₂O₃ and NiO phases, while UV-Vis DRS revealed distinct electronic transitions attributed to Fe and Ni species. TEM and HRTEM images demonstrated a uniform nanorod morphology with clear lattice fringes, and the SAED pattern verified the crystalline nature of the catalyst. The synergistic interaction between Fe and Ni was found to enhance catalytic performance, while computational studies provided mechanistic insight into the reduction pathway, supporting the observed high efficiency of the FeNi CNPs/NiO/Fe₂O₃ system.