Influence of gamma‐irradiation on the photocatalytic activity of undoped and Cu doped titania nanoparticles

Abstract

Copper doped and undoped TiO 2 powders have been prepared by sol‐gel technique and annealed at 400 °C. The powders were gamma irradiated at ambient temperature and doses between 14 and 60 KGy. The objective of the proposed work is to study the effect of gamma irradiation on the physical properties of undoped and Cu doped TiO 2 photocatalyst. The structural, morphological and optical properties of initial undoped and doped TiO 2 powders have been investigated. The performance of such a system strikingly depends on the insertion of impurities in the TiO 2 structure sublattice and of the disruption brought about. Consequently, this work is mainly focused on a nanoscale electron energy loss spectroscopy (EELS) study, which has been performed on samples with various Cu to Ti molar ratios (0‐12at.%). This study is an attempt to identify at the atomic level, the nature of the dopant insertion in the structure. It also allows evaluation of the composition of the studied TiO 2 powders throughout individual crystallites. In Cu doped TiO 2 sol gel powders, Cu 2+ ion has been found to substitute to Ti 4+ ions. Gamma irradiated samples present a crystalline core and a disordered shell structures (see Figure 2) as a result of the formation of oxygen vacancies. Such oxygen vacancies at the surface of TiO 2 nanocrystals lead to a remarkable enhancement of the photocatalytic activity of Cu doped TiO 2 nanocrystals (see Figure 3). This preparation method by gamma treatement could be potentially used for large‐scale production of high‐surface‐area anatase titania nanoparticles with trapped electrons on oxygen vacancies. Such catalysts show remarkable enhancement in the visible light absorption and photocatalytic activity. The doping and gamma irradiation doses impacts on the structural, optical and photocatalytic efficiencies will be thus highlighted and correlated.