Mesoporous gadolinium doped titania photocatalyst through an aqueous sol–gel method

Abstract

A surfactant-free, aqueous sol–gel synthetic route to a thermally stable gadolinium doped mesoporous nanocrystalline titania is reported for the first time. The mesoporosity was revealed using BET surface area measurements and the pores are stable at temperatures as high as 800 °C. The 2 mol% gadolinium doped titania calcined at 800 °C, displayed a specific surface area of 22 m 2 g −1and a total pore volume 0.142 cm 3 g −1, whereas undoped titania is non-porous and has a surface area value as low as 0.3364 m 2 g −1 and total pore volume of 0.00096 cm 3 g −1. The thermal stability of the anatase phase up to 800 °C was achieved due to the reduction of crystallite size as a result of gadolinium doping in the titania lattice. Transmission electron micrographs showed that the crystallite size of 2 mol% gadolinium doped titania is 20 nm at 800 °C, whereas undoped titania had a crystallite size of 43 nm at the same temperature. The Bronsted acidity of doped titania was further studied using 2,6-dimethyl pyridine adsorption studies. Finally the photocatalytic performance of this mesoporous TiO 2 was analysed using methylene blue degradation and revealed a significantly higher activity than the undoped titania, a factor attributed to the mesoporosity, higher surface area and thermal stability of anatase phase.