Green route synthesis of ZnO/Al₂O₃/TiO₂/MgO nanocomposite with enhanced performance in sunscreen formulations and photocatalysis

BACKGROUND: In order to protect human skin from UV radiation, which may lead to sunburn, early aging, and skin cancer, sunscreen formulas are essential. Semiconductor metal oxides are also widely used in photocatalysis for degrading organic pollutants under light irradiation. To maintain effectiveness, as well as environmental friendliness, the development of non-toxic and environmentally friendly UV filters has attracted a lot of attention. In this context, green synthesis approaches offer a sustainable route for producing advanced nanomaterials with improved safety and performance. RESULTS: In this study, ZnO/Al₂O₃/TiO₂/MgO nanocomposites were synthesized via a green route using neem extract as a natural reducing and stabilizing agent. The composite was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). FTIR confirmed bioactive functional groups from the extract, XRD revealed crystalline metal oxide phases, SEM showed uniform nanoscale morphology, and EDX verified the presence of Zn, Al, Ti, Mg, and O. The sunscreen efficacy was evaluated through UV absorbance (290–320 nm) and sun protection factor (SPF) determination using the Mansur equation. The nanocomposite exhibited excellent UV-blocking capability with an SPF of 29.60 and good photostability. It also demonstrated good photostability and achieved 95% degradation of methylene blue at an optimal dosage of 0.035 g under sunlight irradiation, indicating excellent photocatalytic activity. CONCLUSION: This enhanced performance is accredited to synergistic interactions among the metal oxides, leading to improved charge separation. The green-synthesized ZnO/Al₂O₃/TiO₂/MgO nanocomposite demonstrates strong potential as a sustainable multifunctional material for sunscreen and environmental photocatalysis applications.