The Polymer Society of Korea

Abstract

Titanium dioxide (TiO₂, bandgap ~3.2 eV) is extensively used as a UV-blocking agent in sunscreens but suffers from a narrow spectral coverage (~3.2 eV bandgap) and high photochemical reactivity, resulting in undesired reactive oxygen species (ROS). Here, we developed a heterostructure composed of mesoporous SiO₂, N-doped TiO₂, and metal-phenolic networks (MPNs) to achieve comprehensive protection from ultraviolet (UV) to high-energy visible (HEV) light (400–500 nm). Nitrogen doping significantly extended the absorption range into the HEV range while simultaneously serving as recombination sites for photogenerated charges, effectively reducing ROS formation. Furthermore, the incorporation of MPN coatings improved UV-to-HEV protection via ligand-to-metal charge transfer mechanisms and demonstrated intrinsic antioxidant properties, suppressing ROS generation by up to 99%. This multifunctional inorganic-organic heterostructure addresses critical limitations of conventional inorganic UV filters, providing enhanced photoprotection and reduced phototoxicity for advanced sunscreen applications. This research was funded by the Korea Technology and Information Promotion Agency for SMEs (TIPA) (Grant RS-2025-02306912).