Halloysite-Doped Zinc Oxide for Enhanced Sunscreening Performance

Halloysite (Hal) has already been proposed as a support for zinc oxide nanoparticles synthesis due to the possibility of adsorbing ZnO on its internal and external tubular surface, but no attention has been devoted to evaluate the effect of this support on radiation screening capabilities. In this paper, zinc oxide nanoparticles were obtained by three different methods in the presence of Hal. Adsorption, solvent evaporation, and solvothermal methods were used. Quantitative Zn was determined by inductively coupled plasma optical emission spectrometry (ICP-OES), and nanocomposites were characterized by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). This characterization elucidated that three different nanocomposites were obtained. In particular, when the adsorption method was used, small and quite uniform sized (10–30 nm) zinc oxide nanoparticles confined inside the Hal nanotubules were obtained. The UV–vis spectra of these nanocomposites revealed their ability to interact with a wide portion of UV–vis radiation which leads to enhanced sun screening performance.