RESUMO
Heterojunction nanocomposites (ZnO:NiO:CuO) were synthesized via a hydrothermal method and annealed at three different temperatures (400 °C, 600 °C, and 800 °C). The structural, optical, and electrical properties were examined by employing XRD, SEM, UV-Vis, FTIR, and LCR meter techniques to investigate the effects of annealing. Increasing the annealing temperature resulted in the nanocomposites (NCPs) exhibiting enhanced crystallinity, purity, optical properties, and improved electrical and dielectric behavior. The calculated crystalline sizes (Debye-Scherrer method) of the NCPs were determined to be 21, 26 and 34 nm for annealing temperature 400 °C, 600 °C, and 800 °C, respectively. The calculated bandgaps of synthesized samples were found in the range of 2.92-2.55 eV. This temperature-dependent annealing process notably influenced particle size, morphology, band-gap characteristics, and photocatalytic efficiency. EDX analysis affirmed the sample purity, with elemental peaks of Zn, Cu, Ni, and O. These NCPs demonstrated exceptional photocatalytic activity against various dyes solutions (Methyl orange (MO), Methylene Blue (MB), and mixed solution of dyes) under sunlight and also showed good antibacterial properties assessed by the disc diffusion method. Notably, the nanocomposite annealed at 400 °C exhibited a particularly high degradation efficiency by degrading 96% MB and 91% MO in just 90 min under sunlight.
RESUMO
In this article, ZnO:NiO:CuO nanocomposites (NCPs) were synthesized using a hydrothermal method, with different Zn : Ni : Cu molar ratios (1 : 1 : 1, 2 : 1 : 1, 1 : 2 : 1, and 1 : 1 : 1). The PXRD confirmed the formation of a NCP consisting of ZnO (hexagonal), NiO (cubic), and CuO (monoclinic) structures. The crystallite sizes of NCPs were calculated using Debye Scherrer and Williamson-Hall methods. The calculated crystalline sizes (Scherrer method) of the NCPs were determined to be 21, 27, 23, and 20 nm for the molar ratios 1 : 1 : 1, 2 : 1 : 1, 1 : 2 : 1, and 1 : 1 : 2, respectively. FTIR spectra confirmed the successful formation of heterojunction NCPs via the presence of metal-oxygen bonds. The UV-vis spectroscopy was used to calculate the bandgap of synthesized samples and was found in the range of 2.99-2.17 eV. SEM images showed the mixed morphology of NCPs i.e., irregular spherical and rod-like structures. The dielectric properties, including AC conductivity, dielectric constant, impedance, and dielectric loss parameters were measured using an LCR meter. The DC electrical measurements revealed that NCPs have a high electrical conductivity. All the NCPs were evaluated for the photocatalytic degradation of Methylene blue (MB), methyl orange (MO), and a mixture of both of these dyes. The NCPs with a molar ratio 1 : 1 : 2 (Zn : Ni : Cu) displayed outstanding photocatalytic activity under sunlight, achieving the degradation efficiency of 98% for methylene blue (MB), 92% for methyl orange (MO) and more than 87% in the case of a mixture of dyes within just 90 minutes of illumination. The antibacterial activity results showed the more noxious nature of NCPs against Gram-negative bacteria with a maximum zone of inhibition revealed by the NCPs of molar ratio 1 : 2 : 1 (Zn : Ni : Cu). On the basis of these observations, it can be anticipated that the NCPs can be successfully employed for the purification of contaminated water by the degradation of hazardous organic compounds and in antibacterial ointments.
