Single crystalline rhabdophane-type CePO4 nanoparticles as efficient UV filters

Cerium-based materials have shown good results when applied as inorganic UV filters, either absorbing and/or scattering light. Although most papers report the use of Ce(IV), Ce(III) has shown better results for UV protection applications, confirmed by photocatalysis involving the degradation of castor oil, and UV vis reflectance and absorbance spectroscopies. Reverse microemulsions have been widely employed to obtain nanosized particles with controlled morphology, thus water-in-oil microemulsion syntheses of cerium(III) orthophosphates using cetyltrimethylammonium bromide and 1-butanol as surfactant and co-surfactant are reported. Cerium(IV) oxide particles have been synthesized by the same way for concrete comparisons. The variations in the microemulsion compositions and their effects in the morphology and UV filter efficiency have been investigated. Electron micrographs evidence the formation of well dispersed and singly crystalline rhabdophane-type CePO4 nanorods, which display longer lengths as the surfactant amount decreases. The observation of D-2 <- F-2(5/2) Ce3+ transitions, ideal optical band gap energies (2.7-2.8 eV) and, the formation of nanosized particles support the applicability of CePO4 for UV protection. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved. (AU)