TiO2 supported on silica nanolayers derived from vermiculite for efficient photocatalysis

Abstract

Various TiO2 composite photocatalysts were synthesized by immobilizing TiO2 nanoparticles onto the surface of silica nanolayers (SNLs) derived from vermiculite via a simple reaction between titanium hydrate and SNLs by varying Ti/SNLs ratios and using different acidic media (HCl, HNO3 and H2SO4). As-obtained composites were characterized by means of XRD, SEM and BET analytical techniques. The photocatalytic activities of photocatalysts were evaluated using methylene blue (MB) as a model pollutant in aqueous solution. It was found that the acidic media HCl and HNO3 favored the formation of tri-crystalline and flat spongy-like thin layers of TiO2 nanoparticles with large specific surface area giving excellent photocatalytic activity; while H2SO4 medium resulted in the single-phase of anatase TiO2 with ball-like aggregates on the TiO2 thin layer, giving relatively low photocatalytic activity. The excellent performance of the composites obtained using proper SNLs content and suitable acidic medium can be mainly ascribed to the mixed-phase structures with an optimum ratio and large specific surface area, as well as the facile immobilization of TiO2 on the support, which will be beneficial to their separation from water treatment system in practical application.