Mass Production of Multishell Hollow SiO Spheres With Adjustable Void Ratios and Pore Structures.

SiO multishell hollow spheres (MHSs) as supports have multiple porous layers and internal voids, which present notable advantages in regulating mass transport and chemical reactions. However, practical applications of SiO MHSs are severely hindered because of their high costs and low production efficiency issues. Herein, it is overcome these obstacles by developing a precursor hydrolysis method and demonstrate a cost-effective production of void-ratio tunable SiO MHSs on a large scale, which has a much lower cavitation temperature (25 °C) and one order of magnitude decrease in cost. In addition, the new method can also be applied to fabricate TiO and SnO hollow spheres (HSs). In particular, an NHCl precipitation-pyrolysis strategy is developed to tune the pore diameters and pore distributions of SiO MHSs with different void ratios. SiO MHSs with varying void ratios and pore distributions have the broadest controlling release time ranges (30-430 h). The precursor hydrolysis method and NHCl precipitation-pyrolysis strategy offer adequate stimulus to push forward SiO MHSs from laboratory-scale to industry-scale applications.