Synthesis of Monolithic TiO2 Aerogels With Relatively Low Shrinkage and Improved Formability Assisted by CTAB

Monolithic TiO 2 aerogels without severe shrink were obtained by the sol-gel method with the addition of the surfactant cetyltrimethylammonium bromide (CTAB) to control the hydrolysis and polycondensation process and acetonitrile solvent as the solvent to improve the crystallinity. After CO 2 supercritical drying, the shrinkage ratio of monolithic TiO 2 aerogels modified by CTAB decreased by up to ∼26.9%, compared with the pure TiO 2 aerogel. Their apparent densities were all lower than 300 g/cm 3 . X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform infrared spectroscopy (FTIR) and BET Specific Surface Area Analysis were used to analyze the as-synthesized samples. The results revealed that all the samples were anatase-TiO 2 phase with nanoporous network structures. The specific surface areas reached 250.2 m 2 /g confirmed by the BET (Brunaur–Emmett–Teller method) analysis. However, TiO 2 aerogels without the addition of CTAB showed evident agglomeration and collapse of the network in comparison with CTAB-added samples. To further study the structure-property relationship, the photocatalysis performance of as-synthesized and 300°C-calcined aerogels was carried out contrastively. Interestingly, the influences of the CTAB adding amount of as-synthesized and calcined TiO 2 aerogels are negative and positive, respectively, which is probably due to the synergistic effect of CTAB hindrance and grain refinement. Potentially, This kind of TiO 2 aerogels assisted by CATB with low density, small shrinkage, improved formability, high specific surface area and fine crystalline grain may be applied in various applications, such as electrochemistry, photocatalysis, etc.