Aloe vera assisted green synthesis of Ag and Cu co-doped ZnO nanoparticles and a comprehensive analysis of their structural, morphological, optical, electrical and antibacterial properties

Abstract

This study investigates the potential of utilizing Aloe vera-assisted green synthesis with transition metal dopants of Ag and Cu for greater efficiency and sustainability in advanced scientific applications utilizing ZnO nanoparticles. Samples were prepared using the co-precipitation method, maintaining a basic pH media of 10. Aloe vera gel extract was chosen for its acclaimed role as a stabilizing and reducing agent and its proven antioxidant, antibacterial, and anticancer properties. The XRD report revealed the hexagonal Wurtzite crystal structure of nanoparticles, exhibiting a crystallite size range of 17–23 nm with substantial alterations in lattice parameters, dislocation density, and bond lengths when dopants were added. Additionally, EDX analysis confirmed the perfect doping of Ag and Cu in ZnO without any impurities. SEM analysis indicated a reduction in agglomeration, accompanied by a transition in particle morphology from columnar to globular. Additionally, the optical study showed a band gap range of 3.18–3.27 eV, confirming it to be a wide band gap semiconductor. The effect of dopants resulted in an increase in transparency and band gap, while a decrease in absorption coefficient in the visible wavelength region. With increasing temperature, a decline in electrical resistivity was noted, with co-doped nanoparticles consistently exhibiting the lowest resistivity, affirming semiconductor characteristics. Most importantly, A remarkable antibacterial efficacy was noticed at low concentrations against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. The zone of inhibition produced by nanoparticles exhibited values akin to the antibiotic control, even at substantially lower doses. This research offers a comprehensive analysis of the effects of Ag and Cu in Aloe vera-assisted green-synthesized ZnO nanoparticles, concurrently addressing their potential applications in biomedical, energy storage, and optoelectronic devices.