Photocatalytic activity of Acid-Catalyst-modified Sol-Gel processed nanocrystalline Titania: On dual-role of active surface-sites

Abstract

Stabilizing anatase-phase in pure and doped nanocrystalline titania (TiO2) with enhanced photocatalytic activity has been a challenging task. In this report, we synthesize nanocrystalline anatase-TiO2 via the conventional and acid-catalyst-modified sol–gel processes. Three different types of acid-catalysts, HNO3, CH3COOH, and H3PO4, have been utilized for this purpose. The effect of acid-catalyst on the morphological, chemical, and structural evolution of samples has been analyzed using the different analytical techniques. The photocatalytic activity has been measured under the ultraviolet (UV)-radiation exposure by varying the acid-catalyst used, initial dye-concentration, and initial concentration of H3PO4. The maximum photocatalytic activity has been exhibited by the sample processed using the H3PO4 as an acid-catalyst which has been attributed to the ability of PO3− 4 anions to bind strongly with the surface of anatase-TiO2 and their dual-role in the dark and under the UV-radiation exposure leading to the largest amount of dye-adsorption on the surface and highest dye-degradation kinetics