Effect of organic capping agents on the optical and photocatalytic activity of mesoporous TiO2 nanoparticles by sol–gel method

Abstract

In this work, the effect of capping agent effects on the structural, morphological, optical properties and photocatalytic removal of Rhodamine B (RhB) dye has been investigated. TiO2 nanoparticles were synthesized by a simple, fast and eco-friendly sol–gel method, in the presence of various capping agents, including ethylenediamine, polyvinyl alcohol (PVA), ethylene glycol, glucose and valine. The obtained TiO2 nanoparticles have been characterized by X-ray diffraction (XRD), energy dispersive X-ray analysis, high resolution scanning electron microscopy and transmission electron microscopy, UV–visible absorption and photoluminescence (PL) spectroscopy. XRD pattern reveals the polycrystalline nature of TiO2 with anatase structure. The results revealed that the optical absorption band of TiO2 nanoparticles varied by capping agents. PL spectra exhibited visible emissions due to the formation of defects in the band gap region of TiO2 nanoparticles. The photocatalytic degradation of RhB dye by synthesized TiO2 nanoparticles using different capping agents was investigated under UV irradiation and the results demonstrated that TiO2 nanoparticles have appreciable photocatalytic activity for decomposing RhB dye when PVA was used as a capping agent. The results explained that the preparation of TiO2 nanoparticles showed a high efficiency in the removal of organic dyes.