Polyethylene glycol in sol-gel precursor to prepare porous Gd2Ti2O7: Enhanced photocatalytic activity on Reactive Brilliant Red X-3B degradation

摘要

Polyethylene glycol (PEG1000, molecular weight 1000) was used to prepare porous gadolinium titanate via a solgel route. The effects of PEG1000 on the properties of gadolinium titanate photocatalysts were studied. PEG1000 could prohibit crystal growth of pyrochlore structured Gd2Ti2O7 in the materials. The addition of PEG1000 led to a blue shift of the absorption edge of the porous Gd2Ti2O7 (n) samples, whose bandgap energies were between 3.48 eV and 3.75 eV. The surface area and pore volume of the porous Gd2Ti2O7 (n) samples were obviously enlarged from 5.08 m(2)/g and 0.0024 cm(3)/g to 21.55 m(2)/g and 0.0090 cm(3)/g. Both the adsorption capacity and photocatalytic activity of the Gd2Ti2O7 (n) samples had a close correlation to the surface area of the materials. The photocatalytic activity of the Gd2Ti2O7 (n) samples was in accordance with the produced hydroxyl radicals. All the porous Gd2Ti2O7 (n) samples had much improved activity on RBR X-3B degradation, and the Gd2Ti2O7 (1.5) sample had the maximum photocatalytic activity. The reaction rate constants for Gd2Ti2O7 (1.5), Gd2Ti2O7 (4.0) and Gd2Ti2O7 (0) were 0.03055, 0.01656 and 0.00347 min(-1), respectively. Photocatalytic oxidation led to degradation of RBR-X3B molecule, which was proven by the reduced absorption intensities of the organic groups.