Preparation of mesoporous titania xerogels under controlled synthesis conditions. Effects of processing in the textural, adsorption and photocatalytic properties

Abstract

A straightforward and potentially scalable procedure based in the Evaporation-Induced Self-Assembly (EISA) method has been used in order to synthesize mesoporous titania (TiO2) xerogels. The structural, textural and photocatalytic properties of the synthesized materials were determined. The variation of synthesis parameters relative humidity (RH) and temperature, allowed controlling the textural properties of materials that exhibited mesopores with controllable pore and neck diameter distributions in the range of 3?12 nm, large surface area (125?161 m2 g−1) and pore volume values between 0.17 and 0.38 cm3 g−1. Selected area electron diffraction (SAED) and X-ray diffraction (XRD) patterns indicated the presence of anatase phase. The uptake of gallic acid (GA) on these mesoporous powders and Evonik Degussa P25 was measured using Fourier Transform IR (FTIR) spectroscopy. The photocatalytic degradation rates of GA adsorbed on TiO2 were measured and followed by FTIR. The mesoporous materials showed interesting features including efficient trapping of the adsorbate and good photolytic response. The catalysts were exposed to successive cycles of adsorption/photolysis of GA and a very good performance was observed for the mesoporous anatase samples, leading to efficient, recoverable and reusable photocatalysts.