Green synthesis of TiO2/ZnO heterostructure using Urtica Smensis leaf extract for antibacterial activity

An environmentally friendly and low-cost green approach currently gets great attention in medicinal fields. In the present work, we have successfully synthesized TiO₂/ZnO heterostructure (TZH) by using the aqueous extract of Urtica Simensis (U. Simensis) leaf as a reducing and capping agent for the first time. The synthesized TiO₂ and ZnO nanoparticles (NPs) and TZH were characterized by different characterization techniques. The XRD analysis verified the crystallinity and nanoscale crystallite size (12 nm) of the TZH. The TEM/HRTEM analysis verified the nanoscale particle size (36 nm) and formation of TiO₂/ZnO interface within TZH. From the nitrogen adsorption–desorption isotherm analysis, the specific surface area, pore size, and pore volume of TZH were found to be 89.6 m²/g, 6.8  nm, and 0.054 cm³/g, respectively. The antibacterial potential of TiO₂/ZnO was found to be the highest compared to both pristine TiO₂ and ZnO for all four bacterial strains of S. aureus, S. pyogenes, P. aeruginosa, and E. coli. The maximum zones of inhibition of TZH were found to be 20.1, 21.3, 19.4, and 18.5 mm for S. pyogenes, S. aureus, E. coli, and P. aeruginosa, respectively. With this result, the green synthesis approach has a great future outlook for an antimicrobial application.