Bio-derived NiO nanoparticles from Colocasia esculenta leaf extract with enhanced antibacterial activity and efficient photocatalytic degradation of methylene blue

Abstract

Colocasia esculenta leaf extract was utilized for the green synthesis of nickel oxide nanoparticles (NiO NPs) through an easy, phytochemical-mediated, environmentally friendly reduction method. Fourier transform infrared (FTIR) spectroscopic analysis of the nanoparticles revealed that the phytochemicals served as both capping and reducing agents, and the morphology of these nanoparticles was studied using scanning electron microscopy (SEM). The surface plasmon resonance (SPR) peak was observed at 348 nm, the optical band gap was 3.45 eV based on UV-visible analysis, and the crystallite size of the synthesized NPs was 26.89 nm, as evidenced by X-ray diffraction (XRD) analysis. Strong antimicrobial potential was demonstrated against Staphylococcus aureus, Salmonella typhi and Candida albcans, producing inhibition zones of 19.00 ± 0.94 mm, 17.33 ± 0.62 mm and 20.67 ± 0.58 mm, respectively. Additionally, under optimal conditions (30 mg catalyst, 10 mg L⁻¹ dye, pH 8, 80 min), NiO NPs demonstrated effective photocatalytic degradation of methylene blue under natural sun irradiation, attaining up to 96% degradation. Interestingly, after three consecutive cycles, the nanoparticles retained 85% of their photocatalytic activity, demonstrating exceptional stability and reusability. These results demonstrate the promise of Colocasia esculenta-mediated NiO NPs as multipurpose, biocompatible, and reasonably priced nanomaterials for biomedical and environmental remediation applications.