Nanosheet coated dual-shell TiO2 sphere with high solar reflectance for thermal-shield materials

Abstract

A dual-shell TiO2 sphere, composed of a TiO2 sphere (TS) core and SiO2 layer (SL)/TiO2 nanosheet (TNS) double shell, was prepared as a novel thermal-shield material. The high reflective rutile TiO2 core was easily synthesized via a solvothermal reaction, and then SL/TNS double shell was sequentially coated on the TiO2 core via two-step coating. This multilayer structure enhanced the solar reflectance via constructive interference between the high- and low-refractive index layers, suggesting a positive impact on potential applications as a thermal-shielding material. Moreover, the multi-faceted reflection derived from vertical growth TNS outer layer can lead to improvement in the solar reflectance caused by maximization of light scattering. As a result, it showed outstanding near infraredand visible-reflectance value of approximately 87% and 91%, respectively, which are higher than those of neat TS and commercial TiO2.