Eco-Friendly Fabrication of Hematite–ZnO/Chitosan Nanocomposite for Visible-Light-Driven Photocatalytic and Antibacterial Efficacy

Waterborne pathogens are intrinsically hazardous and accumulate within living organisms, leading to health risks. Hybrid materials combining metal oxides and polymers provide synergistic adsorption properties, facilitate the degradation process, and have strong antimicrobial activity against pathogenic microorganisms. To enhance the functions of polymer-based photocatalysis, we synthesized psidium guajava leaf extract- mediated single- phase Fe2O3 (Hematite)-ZnO/Chitosan (HZC) biopolymeric nanocomposite, demonstrating improved photocatalytic activity and potent antibacterial efficacy. The synergistic interactions within the HZC matrix revealed through the characterization analyses (XRD, FTIR, and SEM) confirms a cubic phase structure with space group of Fd-3m possessing an average crystallite size of 28.5 nm, a wide spectrum of abundant amine groups in chitosan results spherical morphology that facilitates effective HZC conjugation. The optical bandgap observed at UV-Vis spectroscopy is 2.0 eV, while XPS analysis demonstrated that oxygen vacancies in chitosan transform the Fe2O3-ZnO nanoparticles from passive candidates into highly active functional materials. The increase in adsorption and surface contact resulted in considerably high dye degradation efficiencies of 91% for methylene blue (MB) and 93% for Rhodamine B for 180 minutes. A gradual increase in the concentration of the HZC nanocomposites demonstrated progressively stronger inhibitory effects against the waterborne bacterial pathogens including S. pneumoniae (23 mm), B. subtilis (24 mm), K. pneumoniae (20 mm), and S. dysenteriae (22 mm) at a concentration of 60 µg/mL. The dual nature of HZC biopolymeric NCs underscores the multifunctional material with promising applications in both photocatalytic and antibacterial applications supported by effective charge separation, surface reactivity, and metal ion release.