Solvent, Catalyst, and Precursor: Parameters of Ge(OR)₄ Hydrolysis for GeO₂ Aerogels Production

The parameters of gel synthesis affect the kinetics and mechanism of hydrolysis and condensation processes, thereby determining the three-dimensional porous structure. In this work, the characteristics of germanium dioxide aerogels were investigated depending on the conditions of preparation. Acetonitrile was chosen as the optimal solvent, and hydrochloric acid was chosen as a catalyst. The concentrational ranges of stable gel existence during the hydrolysis of germanium(IV) tetraethoxide and tetraisopropoxide were determined. The effect of the choice of precursor and water content on the textural characteristics of the aerogel was shown. Mesoporous materials with a specific surface area of 50 m²/g with a wide pore size distribution were obtained. The phase composition of the obtained aerogels in all cases corresponded to the hexagonal modification of germanium dioxide.