Mass Production of Multishell Hollow SiO<sub>2</sub> Spheres With Adjustable Void Ratios and Pore Structures.

Geng, Yuqi; Guo, Xiaojun; Yue, Fen; Xiang, Maoqiao; Zhu, Qingshan · Adv Mater · 2024

basic_science · Level V

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Abstract

SiO<sub>2</sub> 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<sub>2</sub> 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<sub>2</sub> 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<sub>2</sub> and SnO<sub>2</sub> hollow spheres (HSs). In particular, an NH<sub>4</sub>Cl precipitation-pyrolysis strategy is developed to tune the pore diameters and pore distributions of SiO<sub>2</sub> MHSs with different void ratios. SiO<sub>2</sub> MHSs with varying void ratios and pore distributions have the broadest controlling release time ranges (30-430 h). The precursor hydrolysis method and NH<sub>4</sub>Cl precipitation-pyrolysis strategy offer adequate stimulus to push forward SiO<sub>2</sub> MHSs from laboratory-scale to industry-scale applications.