Heterojunction photocatalysts have attracted a significant amount of attention due to their advantages over a single photocatalyst and, particularly, their superior spatial charge separation. Herein, the BiVO4/Bi2S3/SnS2 heterojunction was synthesized via solvothermal synthesis with different ratios of BiVO4 to SnS2. The photodegradation rate of the 0.03 BiVO4/SnS2 sample for rhodamine B removal is 2.3 times or 2.9 times greater than that of a single SnS2 or BiVO4, respectively. The chemical bond between photocatalysts is confirmed by X-ray photoelectron spectroscopy (XPS), and the synchronized shift observed in binding energies strongly indicates the electron screening effect at the heterojunction. A Z-scheme model is proposed to explain charge transfer pathway in the system, in which the formation of Bi2S3 plays a crucial role in the enhanced photocatalytic performance of the heterojunction.
The monoclinic BiVO4 in a powder state was prepared via a hydrothermal method, with the addition of KCl as a structure-directing agent. The as-prepared sample was calcined at different temperatures (400–600 °C), either in the air or in Ar gas. It is found that, though the morphology and crystal structure mostly remain unchanged, the bandgap properties are modified during calcination. A detailed analysis of the surface chemical states and optical absorption properties reveals the involvement of tetravalent vanadium ions and oxygen vacancies as the cause of the band modification. The bandgap properties are to be found tunable via changing the calcination condition, as well as the KCl concentration in the precursor. The photocatalytic properties of BiVO4 samples are greatly enhanced with the addition of KCl in the precursor, but degraded by post-annealing, where the residual Cl in the calcined sample may act as an inhibitor. The enhanced photoactivity is explained in terms of favorable faceting, bandgap modification, and heterojunction of BiVO4/BiOCl.
Recently, many researchers focus on the nanoscale fillers to enhance electrical properties of composite due to the uniqueness of material. In this study, polyimide/barium titanate (BaTiO3) nanofibers films were prepared by incorporating electrospun BaTiO3 nanofibers with polyimide derived from 2,2-Bis [4-(4-aminophenoxy) phenyl] propane (BAPP) and 3,3',4,4'-Biphenyl tetracarboxylic dianhydride (BPDA). The obtained nanofibers were modified with (3-Glycidyloxypropyl) trimethoxysilane as coupling agent before integrating into the polyimide matrix. Microstructure and dielectric properties of BaTiO3 nanocomposites were investigated. The results showed BaTiO3 nanofibers were successfully produced at nanoscale regime and well dispersed in the hybrid film after modification and ultrasonication method. Dielectric constant of the nanofibers films were improved and increased with increasing of BaTiO3 nanofibers concentration while dielectric loss remains relative low.
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