Microstructure, optical, photoluminescence properties and the intrinsic mechanism of photoluminescence and photocatalysis for the BaTiO3, BaTiO3/TiO2 and BaTiO3/TiO2/CeO2 smart composites

Abstract

The BaTiO 3 /TiO 2 /CeO 2 smart composites with double type II band arrangement structures were synthesized by a hydrothermal synthesis method. This study attempted to improve the photoluminescence performance and photocatalytic activity by introducing anatase TiO 2 or two kinds of metal species, cubic CeO 2 and anatase TiO 2 , fabricated as BaTiO 3 /TiO 2 or BaTiO 3 /TiO 2 /CeO 2 smart composites. Rietveld refinement analysis revealed a typical tetragonal structure with P4mm(99) space group of pure BaTiO 3 smart materials and BaTiO 3 /TiO 2 /CeO 2 smart composites consist of tetragonal BaTiO 3 , cubic CeO 2 and anatase TiO 2 . The surface morphology, color, optical absorption coefficient, photoluminescence performance and photocatalytic activity showed strong CeO 2 content - dependent behavior. For the pure BaTiO 3 smart materials, three obvious emission peaks at 420, 460 and 470 nm can be observed when the excitation wavelength is 295 nm. The introduction of TiO 2 into the pure BaTiO 3 smart materials to construct BaTiO 3 /TiO 2 smart composites resulted in redshift of emission peak. When TiO 2 and CeO 2 were introduced into the pure BaTiO 3 smart materials, the intrinsic fluorescence emission peak of BaTiO 3 was almost quenched. Oxygen vacancy, Ce-4f level and impurity level promote the electron hole pair recombination, which is beneficial to enhance the photoluminescence of the system, but unfavorable to their photocatalytic activity. The BaTiO 3 /(15 wt%) TiO 2 /(15 wt%) CeO 2 smart composites exhibit a highest photocatalytic activity for the photocatalytic degradation of methylene blue under ultraviolet light irradiation. • A hydrothermal synthesis method have been used to synthesize the BaTiO 3 /TiO 2 /CeO 2 smart composites. • The optical, photoluminescence properties and photocatalytic activity of BaTiO 3 /TiO 2 /CeO 2 smart composites were compared. • Possible photoluminescence and photocatalysis mechanisms have been proposed.