Highly Solar-Reflective Litchis-Like Core-Shell HGM/TiO 2 Microspheres Synthesized by Controllable Heterogeneous Precipitation Method

Hollow glass microsphere (HGM)/TiO 2 core-shell structural composites have promising applications in the field of energy efficient solar-reflective paints. In this work, after pretreated with saturated Ca(OH) 2 solutions, litchis-like TiO 2 shells have been successfully synthesized on HGMs via a controllably heterogeneous precipitation method with Titanium (IV) sulfate (Ti(SO[Formula: see text] and urea as reaction precursors. It is emphasized that the use of urea as the precipitating agent is essential for the heterogeneous nucleation and growth of Ti(OH) 4 on HGMs, while the Ca(OH) 2 pretreatment provides the heterogeneous nucleation sites on HGMs which promotes the nucleation and growth of Ti(OH) 4 , and gives rise to large secondary Ti(OH) 4 particles, leading to the formation of litchis-like TiO 2 shells. The resulted core-shell structural HGM/TiO 2 microspheres exhibited highest solar reflectance of [Formula: see text]83%.