Development of titanium-dioxide-based aerogel catalyst with tunable nanoporosity and photocatalytic activity

Nanostructured highly porous TiO2/WO3/Fe3+ aerogel composite photocatalysts are prepared, characterized and tested for model photocatalytic reactions. The catalyst structure is tailored to capture environmental pollutants and enable their decomposition in situ under both ultraviolet (UV) and visible light through oxidation to smaller benign molecules. A novel and green method is utilized to prepare the unique surfactant-templated aerogel composite photocatalyst that has a highly accessible porous nanostructure with high surface area and tailored pore size distribution. The sol–gel process is combined with supercritical extraction and drying. Supercritical drying with heat treatment results in titanium dioxide with anatase crystal form. Templates used further enable retention and tuning of the nanopore structure and surface properties. The synthesized catalysts were characterized using SEM, FIB, XRD and porosimetry prior to post-evaluation in model reactions. The bandgap of the catalyst particles was also determined using diffuse reflectance. The resulting aerogel TiO2/WO3/Fe3+ has similar photocatalytic capability compared to highly optimized commercial Degussa P25 under UV exposure and offers much superior photocatalytic capability under visible light exposure. The model reaction utilized employed methylene blue (MB) photooxidation under visible and UV light. (paper)