Synthesis of ZnO and Cu-doped ZnO Nanoparticles using Aloe Vera leaf extracts and evaluation of their antibacterial and photocatalytic activities

Abstract

In recent years, nanoparticles synthesis by biological method has gained extensive attention due to its low cost, simplicity, non-toxic and environmentally-friendly nature, compared with chemical and physical synthesis methods. The aim of this study is to fabricate Aloe vera leaf extract supported ZnO and Cu-doped ZnO nanoparticles for their photocatalytic and antibacterial activities evaluation. ZnO and Cu-doped ZnO nanoparticles were prepared from zinc nitrate hexahydrate and copper nitrate trihydrate using the plant extract. The synthesized nanoparticles were characterized by using UV-Vis, FT-IR, XRD, and SEM spectroscopic techniques, and tested as antibacterial and photocatalysts. The UV-Visible spectra showed absorbance peaks at 358 nm, 365 nm, and 379 nm, which correspond to the characteristic band of ZnO, 1% Cudoped ZnO, and 4 % Cu-doped ZnO nanoparticles respectively. FT-IR confirmed the nature of bonds and functional groups in the leaf extract, ZnO and Cu-doped nanoparticles. The XRD analysis reveals all the synthesized particles have a crystalline nature with a particle size of 19.24 nm, 23.74 nm, and 24.91 nm of ZnO, 1% Cu-doped ZnO and 4% Cu-doped ZnO NPs respectively. SEM image showed irregular, crushed-ice, and spherical shapes of the NPs. The antibacterial activity studies of the synthesized 1% Cu- doped ZnO and 4 % Cu-doped ZnO Nps against Staphylococcus aureus, Bacillus cereus, Escherichia. Coli and salmonella typhi showed good potential with the reference to the selected standards Gentamicin and DMSO. The maximum zone inhibition activities were found against gram-positive (B. cereus and S. aureus) for 4% Cu-doped ZnO NPs followed by 1% Cu-doped ZnO NPs, whereas minimum inhibition zone were seen against gram-negative (E.coli and S.typhi). 1% Cu-doped ZnO and 4% Cu-doped ZnO NPs displayed good degradation efficiency, 78.48% and 88.07% respectively after 180 min of irradiation, 4% Cu-doped ZnO NPs showing better photocatalytic efficiency.