Green synthesis of gallium-doped zinc oxide nanoparticles using piper betle extract for antibacterial applications

This report investigates the green synthesis of gallium (Ga)-doped zinc oxide (ZnO) nanoparticles, utilizing Piper betle leaf extract as a plant-based reducing and stabilizing agent, along with various characterizations. Undoped ZnO and Ga-doped ZnO at concentrations of 0.5 %, 1 %, and 2 % (ZO, GZO 0.5 %, GZO 1 % and GZO 2 %) were fabricated applying a co-precipitation method. The successful substitution of Ga³ ⁺ ions within the ZnO lattice was confirmed through structural characterization via X-ray diffraction (XRD), showing the formation of the hexagonal wurtzite structure without any secondary phases. As the doping concentration increased, the XRD analysis indicated a reduction in crystallite size, while scanning electron microscopy (SEM) illustrated smaller grain sizes and enhanced homogeneity, which were attributed to the suppression of crystal growth. Using energy-dispersive X-ray spectroscopy (EDX), the elemental composition and successful incorporation of Ga were confirmed. The obtained bandgap of ZO is 3.95 eV, increases to 4.02 eV for GZO 0.5 %, and then slightly decreases to 3.99 eV and 3.96 eV for GZO 1 % and GZO 2 %, respectively. Antibacterial screening against Escherichia coli and Staphylococcus aureus bacterium confirmed that Ga-doped ZnO had larger inhibition zones, particularly at higher doses. The results demonstrate the feasibility of using Ga-doped ZnO nanoparticles made using environmentally friendly techniques for antimicrobial therapy and environmental cleanup, in accordance with the principles of green chemistry.