Insight into the role of Mg/B and Mg/Cu dual dopant on the properties of ZnO nanoparticles prepared by facile one-step combustion route for photocatalytic and antibacterial application

Abstract

ZnO semiconductors are widely known to have benefits in photocatalytic and antibacterial applications. In this study, (Mg/B)–ZnO and (Mg/Cu)–ZnO were synthesized using the combustion method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), UV–Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The XRD results confirmed a decrease in the crystal size and an increase in the crystallinity of the doped ZnO samples. SEM analysis confirmed the morphological changes in the structure from rod-shaped to spherical, and the particle size decreased in the doped ZnO samples. EDS analysis validated the nanoparticle composition of Zn, O, Mg, B, and Cu without impurities. Raman spectra confirmed the formation of defects due to the substitution of dopants in the ZnO lattice. All samples for FTIR analysis showed functional chemical group vibrations from Zn–O, C–H, and O–H stretching. The existence of dopant bonds with oxygen was also validated from this analysis. The change in band gap energy was observed from 3.13 to 3.10 eV in Mg/Cu–ZnO and 3.12 eV in Mg/B–ZnO sample due to the influence of the addition of dopant ions. The XPS spectra show the chemical composition of the nanoparticle samples and the oxidation numbers that correlate with the results of EDS and XRD analyses. A decrease in the emission intensity in the PL measurement was observed in the green emission region in the Mg/B–ZnO sample, which correlated with the decrease in electron recombination. The Photocatalytic application was performed by measuring its ability to degrade methyl violet dye under visible-light irradiation. The maximum deterioration after 120 min of irradiation was obtained for the Mg/Cu–ZnO, Mg/B–ZnO, and ZnO samples at 92.62 %, 92.20 %, and 80.89 %, respectively. Antibacterial activity increased against S. aureus bacteria in co-doped ZnO samples with inhibition zones of 12.15 mm, 8.15 mm, and 6.45 mm for Mg/B–ZnO, Mg/Cu–ZnO, and ZnO samples, respectively.