Eco-friendly synthesis of Nb-doped Fe2O3 nanoparticles using Acacia nilotica leaf extract for photocatalytic and antibacterial applications

Abstract

In this study, Fe₂O₃ nanoparticles (NPs) were synthesized using Acacia nilotica (kiker) leaf extract, which acted as a stabilizing agent. The nanoparticles were then doped with niobium at concentrations of 5 %, 10 %, and 15 % through hydrothermal process. The goal of the work was to evaluate the effect of doping concentrations on both photocatalytic performance, specifically in the degradation of methyl orange (MO) and methylene blue (MB), and antibacterial activity against two Gram-negative bacteria (P. denitrificans, P. maltophilia) and two Gram-positive bacteria (P. streptococcus, B. subtilis). The structural and functional properties of the undoped and Nb-doped Fe₂O₃ NPs were examined through various characterization techniques. These included Fourier Transform Infrared Spectroscopy (FTIR) for vibrational and rotational properties, X-ray Diffraction (XRD) for structural analysis, Dynamic Light Scattering (DLS) for particle size distribution, zeta potential for surface charge, and UV–visible spectroscopy for optical properties. PL spectroscopy showed that the band edge emission occurred at around 1.76 eV. SEM and EDX showed the morphology and element composition of the NPs. SEM showed the hexagonal shapes. Photocatalytic studies under sunlight revealed that the 15 % Nb-doped Fe₂O₃-NPs exhibited the highest degradation efficiency, achieving 70 % methylene blue (MB) and 55 % methyl orange (MO) degradation in 150 and 180 minutes, respectively. Among the undoped samples, the 5 % Nb-doped Fe₂O₃-NPs displayed the most potent antibacterial activity, particularly against Paracoccus denitrificans (P. denitrificans).