CeO2-based nanocomposites: An advanced alternative to TiO2 and ZnO in sunscreens

To encounter the increasing risk of melanoma as well as sunburns and premature ageing, tremendous efforts are being put forwarded by the researchers to improve the existing sunscreen materials used in cosmetics. Skin irritation and photoinstability issues of the organic filters motivate researchers to develop suitable alternatives based on inorganic oxides such as titanium dioxide (TiO2) and zinc oxide (ZnO). Though these inorganic oxide-based UV filters are commonly used in sunscreens, their high oxidation catalytic activity, photocatalytic ability, toxicity, and unaesthetic formulations further encourage researchers to recognize other inorganic alternatives. In this direction, cerium oxide (CeO2)-based nanocomposites including CeO2 are considered to be attractive. However, catalytic oxidation is the prime limitation of such composites toward their applicability in commercial sunscreens. A thorough review of the attempts made by the researchers to understand such bottleneck of CeO2-based nanocomposites is thus essential. In this review article, the UV shielding ability of CeO2-based nanocomposites and CeO2 is primarily focused. In particular, the approaches taken so far to maximize the usefulness in terms of UV shielding, photostability, oxidation stability, and toxicity issues of CeO2-based nanocomposites as potential inorganic UV filters in commercial sunscreens over most common inorganic counterparts, i.e., TiO2 and ZnO are highlighted and emphasized.