Synthesis of copper oxide nanoparticles by chemical and biogenic methods: photocatalytic degradation and in vitro antioxidant activity

Copper oxide nanoparticles (CuO-NPs) were synthesized using two different methods (chemical and biosynthesis) to study the influence of the preparation method on the structural, optical, morphological, photocatalyst, antibacterial and in vitro antioxidant of these nanoparticles. The synthesized nanoparticles were analysed by XRD, UV–Vis, HR-TEM, DLS, ZE, PL and FT-IR spectroscopy. The X-ray diffraction spectra showed the single-phase monoclinic structure of copper oxide, with an average crystallite size of 2.05–3.00 nm. HR-TEM analysis confirmed the spherical morphology of the synthesized CuO-NPs using chemical and biological methods with an average size of 32 nm and 25 nm, respectively. The synthesized CuO-NPs exhibited potential photocatalytic activity towards the degradation of methylene blue dye on exposing to sunlight irradiation. The degradation effectiveness against methylene blue dye was found to be 85 and 97% for chemical and biosynthesized CuO-NPs, respectively. Furthermore, antibacterial and antioxidant activities were evaluated. The biogenic method showed a significant antibacterial activity against Gram-negative bacteria E. coli and B. subtilis than Gram-positive bacteria and also DPPH assay.