Silica Aerogel: Synthesis, Characterization, Applications, and Recent Advancements

Abstract

Silica aerogels have drawn considerable attention due to their low density (almost 95% of the total volume is composed of air), hydrophobicity, optical transparency, low conductivity of heat, and large surface to volume ratio. Sol–gel processing is used to prepare aerogels from molecular precursors. To replace the pore fluid with air while retaining the solid network, a supercritical drying process (the most frequent approach) is used. However, recent technologies use atmospheric pressure to allow for liquid removal followed by chemical alteration of the gel's internal layer, which leaves only a silica network with a porous structure filled with air. This study discusses the sol–gel method for preparing silica aerogels and their various drying processes. Furthermore, various areas of applications of silica aerogels, including electronics, construction, aerospace, purification of water and air, sensing, catalyst, biomedical, absorbent, food packing, textile, etc., are also discussed. Lastly, this review provides a perception of the recent scientific progress along with the futuristic development of silica aerogel.