The Photoluminescence Of H_1.77 [Sr_0.8 Bi_0.21Ta₂ O₇] Nano-layers Annealing Under Different Temperatures And The Effect Of The Cu₂O Addition On Its Photocatalytic Activity

Bi₂SrTa₂O₉ (BST) is a traditional ferroelectric material. It has attracted much attention since its excellent ferroelectric properties in the form of thin film. BST could be protonated into H1.77[Sr_0.8Bi_0.21Ta₂O₇] through an acid treatment because its layer distance is relatively large and interlayer ion is feasibly removable. Thus, it exhibited interesting properties, such as effective water splitting ability under UV light irradiation and emission of blue light under the excitation of near 305 nm. The layered perovskite microstructural and physical properties has just begun to be studied. In the thesis, we discussed two parts, one is the effect of annealing on the photoluminescence of layered perovskite H1.77[Sr_0.8Bi_0.21Ta₂O₇] powders. The other is to have a try to enhance its photocatalytic efficiencies using the combination of Cu₂O.Firstly, the synthesis of BST powder was conducted by a conventional solid-state procedure. H1.77[Sr_0.8Bi_0.21Ta₂O₇] could be obtained by an HCl treatment. The microstructural and luminescent properties of H1.77[Sr_0.8Bi_0.21Ta₂O₇] powders under different dehydrating conditions were investigated. A new study was as follows: (1) The thermogravimetric analysis showed that there is an obvious dehydration temperature range from 200 to 400 0C. (2) The excitation and emission peaks were shifted to longer wavelength while its intensity is getting stronger with the increasing of the annealing temperature from 200 to 400 0C. The peaks intensity is getting strongest when the annealing temperatures was 400 0C. (3) The changing of excitation peak position is consistent with the changing of microstructure during the dehydration. This work was published in Materials Research Bulletin. Secondly, it was reported the p-type semiconductor Cu₂O with a band gap about 2.0 eV to be a very good sensitizer to improve the photocatalytic activity of TiO₂ in solar energy utilization. TiO₂/Cu₂O heterostructures effectively inhibits the recombination of electron-hole pairs, and the absorption to visible light was greatly extended. H1.77[Sr_0.8Bi_0.21Ta₂O₇] is an n-type semiconductor with wide energy band gaps, so the photocatalytic activity of the photocatalyst could only be existed under UV light irradiation. Thus, in this thesis, the photocatalytic efficiency of the Cu₂O/H1.77[Sr_0.8Bi_0.21Ta₂O₇] heterostructures with the Cu₂O different concentrations was studied by degradation of Rhodamine B under visible light irradiation. The result showed that the Cu₂O/H1.77[Sr_0.8Bi_0.21Ta₂O₇] heterostructures with the Cu₂O 10% concentrations has the best photocatalytic efficiencies.