Structure, Property, and Functionality of 2D ZnO Microplatelets with Low Photocatalytic Activity for Application as UV Filters in Sunscreens for Photoprotection

This study focuses on the synthesis and characterization of 2D polygonic ZnO microplatelets for application as UV filters in sunscreens. ZnO microplatelets are obtained via a simple method involving chemical precipitation, aging, and calcination. XRD, SEM, and TEM analyses confirm the successful formation of ZnO microplatelets. DRUV-Vis studies indicate that the ZnO microplatelets have a band gap energy value of 3.2 eV and exhibit good UV radiation absorption, similar to a commercial ZnO reference sample. Furthermore, in methylene blue photodegradation studies, the ZnO microplatelets show significantly lower photocatalytic activity than the ZnO reference sample. Under UV irradiation of 254 nm and 365 nm wavelengths, the dye in contact with ZnO microplatelets is photodegraded by only 38 % and 69 % after 5 h, compared to the reference sample, which photodegraded the dye by 87 % and 97 %, respectively. The performance of a sunscreen formulation containing the ZnO microplatelets (at 10 wt %), in terms of the photoprotection factors and photostability, is on par with that of a formulation containing the ZnO reference sample. Due to their microplatelet structure, good UVR absorption capacity, and relatively lower photocatalytic activity, the ZnO microplatelets show potential for application as UV filters in sunscreen products.