Comparative Study on Solvothermal and Sonochemical Synthesis of Zinc Oxide Nanomaterials and Unraveling the Efficacy in Sunscreen Formulations for Enhanced UV Protection

Abstract As the demand for highly efficient UV‐protective sunscreens continues to rise, the exploration of advanced materials becomes imperative. This paper introduces a novel approach to synthesizing zinc oxide (ZnO) nanomaterials through one‐step solvothermal (ZnO−A) and sonochemical (ZnO−B) methods, eliminating the need for stabilizers or capping agents. The materials have undergone rigorous characterization, focusing on structural and optical properties, and are subsequently evaluated for their UV shielding efficacy. The synthesized ZnO nanomaterials are seamlessly incorporated into a pure cream matrix at varying concentrations (5, 10 and 15 wt. %), offering a versatile application for skin protection against UVA/UVB irradiation. Remarkably, the cream with 15 wt. % ZnO−A emerges as a standout performer, demonstrating immense UV blocking efficacy with 96.44 % for UVA and 97.22 % for UVB. The in vitro sun protection factor (SPF) value of 30.76 further underscores its exceptional performance. This research not only establishes a comprehensive comparative analysis of ZnO−A and ZnO−B nanomaterials but also emphasizes their potential as active ingredients in next‐generation skin care sunscreen formulations. The findings contribute to the ongoing efforts in advancing UV protection technologies, addressing both efficacy and safety considerations.