Zn₂SnO₄ ternary metal oxide for ultraviolet radiation filter application: a comparative study with TiO₂ and ZnO

Ultraviolet (UV) radiation causes serious health risks. Inorganic metal oxides, such as titanium dioxide (TiO₂) and zinc oxide (ZnO), have long been recognized for their effectiveness as UV radiation filters/blockers in sunscreen formulations. TiO₂ and ZnO as UV-blocking materials have some limitations and issues such as producing harmful radicals and toxicity, respectively. As a result, there is a growing need to develop efficient and safe UV-blocking materials to overcome these limitations associated with the conventional TiO₂ and ZnO materials. Zinc stannate (Zn₂SnO₄), as a ternary metal oxide, is expected to be a promising candidate due to its optical properties and potential for UV-blocking capability. This study presents a comprehensive investigation into the development and characterization of Zn₂SnO₄ as a potential alternative UV filter to TiO₂ and ZnO. The fundamental characteristics, including structural, optical, and photocatalytic characteristics, as well as cell viability, were investigated for two Zn₂SnO₄ morphologies: cubic aggregate Zn₂SnO₄ nanoparticles (ZTO CANP) and Zn₂SnO₄ nanoparticles (ZTO NP), which were compared with the performance of TiO₂ nanoparticles (TiO₂ NP) and ZnO nanoparticles (ZnO NP). Interestingly, in addition to their promising UVB and partial UVA blocking properties, ZTO CANP and ZTO NP were found to be relativity photocatalytically inactive materials, which means they produce less free radical species as in the case of TiO₂ NP, and they cannot be considered as toxic materials as in the case of ZnO NP. To the best of our knowledge, this is the first direct comparison study examining the performance of Zn₂SnO₄ ternary metal oxide for its potential use as a UV filter. Further research and optimization need to be conducted on these materials, particularly on ZTO CANP as a promising alternative UV filter.