Ni Doping‐Induced Synergistic Enhancement of Antimicrobial Activity in Biogenically Synthesized ZnO Nanosheets

ABSTRACT In the present study, Ni‐doped ZnO nanosheets (NS) were successfully synthesized via biogenic route, utilizing Azadirachta indica (neem) leaf extract. This plant is commonly known for its medicinal uses, served as a sustainable reducing and stabilizing agent in the biogenic synthesis process. The synthesized Ni‐doped ZnO NS were systematically characterized to evaluate their structural, optical, morphological, and thermal properties using a range of analytical techniques, including powder‐XRD, HR‐TEM, SEM, FTIR, UV‐visible absorption spectroscopy, photoluminescence spectroscopy, and thermogravimetric analysis. Biogenically synthesized samples showed nanosheet‐like morphology in HR‐TEM and SEM analyses, leading to an increased surface area. The incorporation of Ni 2+ ions into ZnO NS, confirmed by analytical techniques, resulted in a synergistic effect that significantly enhanced the NS’ antimicrobial performance. Antibacterial activity was evaluated against Escherichia coli and Staphylococcus aureus to assess broad‐spectrum efficiency. The Ni doping was found to improve reactive oxygen species (ROS) generation and increase surface positive charge, resulting in greater bacterial membrane interaction—particularly against E. coli . The antimicrobial performance of the biogenically synthesized Ni‐doped ZnO NS closely matched that of its chemically synthesized Ni‐doped ZnO NPs, demonstrating the potential of eco‐friendly synthesis routes in developing effective antibacterial nanomaterials.