Visible light photocatalytic activity enhancing of MTiO3 perovskites by M cation (M = Co, Cu, and Ni) substitution and Gadolinium doping

Abstract

The photocatalytic activity of the undoped and Gadolinium-doped MTiO3 perovskites (M = Co, Cu, and Ni) was investigated via degradation of methylene blue as a model organic pollutant under Xenon lamp as a visible light source. For this object, undoped and Gd-doped MTiO3 (M = Ni and Cu) perovskites were synthesized through the facile Pechini method, and an ethylene glycol-mediated route was used for the synthesis of undoped and Gd-doped CoTiO3. Synthesized perovskites were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), N2 adsorption/desorption and photoluminescence (PL) analysis. The results indicated that the photocatalytic activity of the MTiO3 perovskites (M = Co, Cu, and Ni) was improved by introducing 2% of Gd3+ ions into crystallite lattice of perovskites. The observed improvement can be attributed to the size decrease of perovskites, specific surface area enhancement, and decrement in the recombination rate of photogenerated electrons and holes resulted from doping Gd ions. 2% Gd-doped NiTiO3 represented the best photocatalytic activity. Moreover, the results demonstrated that methylene blue molecules are mainly degraded by photogenerated holes and superoxide anion radicals.