Background: Novel photocatalytic materials with promising activity are always the most
important research focus. The preparation of Sm2Ti2O7 by sol-gel method is hardly found in the literature.
Modification of Sm2Ti2O7 by PEG template is interesting for the purpose of synthesizing
porous Sm2Ti2O7 material.
Methods: Sm2Ti2O7 photocatalyst was synthesized by sol-gel method using PEG4000 as a template.
The samples were characterized by XRD, SEM, FT-IR/FIR, UV-Vis DRS, N2 desorption-adsorption,
TG and PLS methods. Adsorption and photocatalytic decolorization of RBR X-3B were examined.
Results: Pyrochlore phase Sm2Ti2O7 in the Fd3m lattice of cubic crystal system begins to form at
800 °C. Crystallite size and cell volume of Sm2Ti2O7 are enlarged with increasing calcination temperature.
The bandgap energies of the samples calcined at 800, 900 and 1000 °C are 3.36, 3.41 and
3.48 eV, respectively. The increase in calcination temperature leads to enlarging pore size and reducing
surface area and pore volume. The maximum •OH radicals are produced on the Sm2Ti2O7 sample
calcined at 900 °C, accompanied with the optimal photocatalytic activity.
Conclusion: High temperature thermal treatment is favorable for crystallization and crystal growing
of pyrochlore phase Sm2Ti2O7. The bandgap energies of the Sm2Ti2O7 samples are enlarged with
rising calcination temperature. The increase in calcination temperature leads to enlarging pore size
and reducing surface area and pore volume. The production efficiency of hydroxyl radical is proportional
to photocatalytic activity of the materials. The Sm2Ti2O7 calcined at 900 °C has the maximum