Modulating the textural properties and photocatalytic hydrogen production activity of TiO2 by high temperature supercritical drying

We report a facile method for the synthesis of TiO2 aerogels by a single step high temperature supercritical drying (HTSCD) of sol-gel derived TiO2. The morphological and structural features of the resultant materials were determined by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, Diffuse Reflectance (DR) spectra, and Fourier Transform infra-Red spectroscopy (FT-IR) measurements. The materials exhibited enhanced solar hydrogen production from water using methanol as sacrificial reagent under Ultra-Violet (UV) light in the absence of Pt as a co-catalyst. Among the TiO2 aerogel samples synthesized, TiO2-M-6h evolved 390 μmol g−1 of H2 after 4 h of irradiation, whereas TiO2-M-2h produced 217 μmol g−1 of H2 after 4 h of irradiation under identical conditions, indicating the importance of aging the gels prior to HTSCD step. The enhancement was credited to increase in surface area, and decrease in particle size in TiO2-M-6h as evidenced from N2-sorption and DRS studies respectively. Upon comparison with a room temperature synthesized TiO2-xerogel, the aerogel materials exhibited enhanced hydrogen production. The results validate the superior performance of TiO2 aerogel materials over TiO2 xerogels and indicate the potential of HTSCD method for the preparation of titania aerogels for solar energy applications.