Copper Oxide-Nickel oxide nanocomposites synthesized via Allium cepa peel extract for photocatalytic degradation of methylene blue

Abstract

Phyto-mediated synthesis of nanomaterials is attractive for its simplicity, non-toxicity, and eco-friendliness. This study focused on synthesizing copper oxide/nickel oxide nanocomposites (Cu-NiO NCs) using Allium cepa peel extract and their efficacy was evaluated against methylene blue (MB) dye degradation. Phytochemical investigation of the plant extract exposed the existence of alkaloids, flavonoids, tannins, phenols, and saponins, which aided in nanoparticle synthesis. Characterization using Ultraviolet Visible (UV–Vis), Fourier transform infra-red (FT-IR), X-ray diffraction (XRD) spectroscopies, and scanning electroscope microscopy (SEM) revealed band gaps of 3.55, 3.38, and 3.02 eV and particle sizes of 6.15, 6.89, and 7.73 nm for NiO NPs, 2 % Cu-NiO NCs, and 5 % Cu-NiO NCs, respectively. Besides, the degradation efficiencies of MB were 86.48 %, 94.92 %, and 97.36 %, using the most optimum catalyst under visible light source in 70 min. Finally, the reusability of the photocatalysts was evaluated in three consecutive cycles, which showed a decrease in degradation efficiency of only 21.58 %, 7.17 %, and 7.95 % for NiO NPs, 2 % Cu-NiO NCs, and 5 % Cu-NiO NCs catalysts, respectively indicating good reusability of the catalysts. The study highlights Cu-NiO NCs as promising photocatalysts for MB dye degradation.