Pure BiFeO3, Bi2Fe4O9, and BiFeO3/Bi2Fe4O9 heterostructure nanofibers were successfully synthesized by a facile wet chemical process followed by an electrospinning technique. Compared with the pure BiFeO3 and Bi2Fe4O9 nanofibers, the introduction of Bi2Fe4O9 in the BiFeO3 makes its absorption edge red shift to absorb much more visible light, and improves its separation efficiency of photogenerated carrier. Besides, the as-obtained BiFeO3/Bi2Fe4O9 nanofibers exhibit higher photocatalytic activity in both the degradation of Rhodamine B and H2 evolution from water under visible-light irradiation. The BiFeO3/Bi2Fe4O9 nanofibers exhibited about 2.7 times and 2.0 times higher H2 evolution than that of pure BiFeO3 and pure Bi2Fe4O9 samples, respectively. The possible photoreactive mechanism of the BiFeO3/Bi2Fe4O9 nanofibers was carefully investigated according to the results of photocatalytic and photoelectric performance, and a Z-scheme mechanism was proposed. Such BiFeO3/Bi2Fe4O9 heterostructure and its composing strategy may bring new insight into the designing of highly efficient visible-light-responsible photocatalysts.Keywords: BiFeO3/Bi2Fe4O9 heterojunction nanofiber; Photoelectric performance; Water splitting Z-scheme mechanism;

In this study, C3N4@Ag-Bi2WO6 with flower-like architecture was successfully prepared through a facile process. The C3N4@Ag-Bi2WO6 particles with 2–4 μm diameters present remarkable enhanced visible light absorption and electron–hole separation efficiency. Compared with Bi2WO6, Ag-Bi2WO6, and C3N4@Bi2WO6 systems, the C3N4@Ag-Bi2WO6 system exhibits optimal photocatalytic activities in both the degradation of RhB and hydrogen production out of water under visible light irradiation. We propose that these results are attributed to the synergy effects of Ag, g-C3N4, and Bi2WO6 nanophase structures in the C3N4@Ag-Bi2WO6 composites, which results in a fast electron–hole separation and slow charge recombination by a Z-scheme mechanism and ultimately in a higher photocatalytic activity.Keywords: Bi2WO6; C3N4-based nanocomposite; photocatalysis; silver; Z-scheme mechanism

One-dimensional BiFeO3/TiO2 heterostructure nanofibers with high visible-light photocatalytic activity have been successfully obtained via a facile hydrothermal process followed by an electrospinning technique. The results show that the BiFeO3/TiO2 nanofibers are as long as dozens of micrometers with the diameters of about 100–300 nm, where BiFeO3 nanoparticles are surrounded by anatase-type TiO2 nanocrystals. Compared with the corresponding pure BiFeO3 nanoparticles, and TiO2 nanofibers, the as-prepared BiFeO3/TiO2 nanofibers exhibit a markedly enhanced photocatalytic activity in the degradation of methyl blue under visible light irradiation. The enhanced photocatalytic activity is attributed to the formed p–n heterojunction between BiFeO3 and TiO2, which results in synergistic enhancement. Notably, the BiFeO3/TiO2 nanofibers could be easily recycled without the decrease in the photocatalytic activity because of their one-dimensional nanostructural property. With their high degradation efficiency and fine recyclability, the BiFeO3/TiO2 heterostructure nanofibers will have wide application in photodegradation of various organic pollutants.

In this work, a novel photocatalyst, polypyrrole (PPy)-decorated Ag-TiO2 nanofibers (PPy-Ag-TiO2) with core–shell structure, was successfully synthesized using an electrospinning technique, followed by a surfactant-directed in situ chemical polymerization method. The results show that a PPy layer was formed on the surface of Ag-TiO2 nanofiber, which is beneficial for protecting Ag nanoparticles from being oxidized. Meanwhile, the PPy-Ag-TiO2 system exhibits remarkable light absorption in the visible region and high photocurrent. Among them, the 1%-PPy-Ag-TiO2 sample shows the highest photoactivity, which is far exceeds that of the single- and two-component systems. This result may be due to the synergistic effect of Ag, PPy, and TiO2 nanostructures in the ternary system.Keywords: conducting polymer; core−shell structures; nanofibers; photocatalysis; silver; TiO2-based nanocomposites;

Polyaniline (PANI)–TiO2 nanocomposites possessing both nano and microscale structures were prepared through a facile hydrothermal route in the presence of PANI. The nanopapilla particles were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, X-ray photoelectron spectra, X-ray diffraction, FTIR spectra, UV–Vis spectroscopy, and N2 adsorption analysis, etc. The results show that the composites possess both nano and microscale structures. The TiO2 nanorods are dispersed on PANI with one end fixed to the surface. The photocatalytic properties of the powders were verified by the photodegradation of gaseous acetone under UV (λ = 254 nm) and visible-light irradiation (λ > 400 nm). In fact, the photocatalytic effects exhibited by the composite particles were superior to that of pure TiO2 and P25 samples. This excellent behavior is attributed to the structural features of PANI–TiO2 microspheres and the synergistic effect between PANI and TiO2 which facilitates a larger amount of surface active sites. This in turn causes a faster charge separation and slower charge recombination which results in a more efficient decomposition of gaseous pollutants.

Aimed at the increasement of ER effects, a novel composite, urea doped-TiO2 particles (TU) were prepared by using a modified sol–gel method. The structure and morphology of the TU particles were observed and analyzed by scanning electron micrpscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometry(FT-IR) and X-ray photoelectron spectrum (XPS). The dielectric properties of the TU particles and the ER effects based on the TU particles were investigated. The influence of wettability on the ER performance between the particles and silicone oil was examined.

Urea-doped BaxSr1−xTiO3 particles (BSTU) were prepared by a modified sol–gel method. The structure and morphology of the BSTU particles were characterized. The dielectric properties of the BSTU particles and the electrorheological (ER) effects of the ER fluids based on these particles were investigated. The results show that the ER performance of those fluids is much higher than that of pure BaxSr1−xTiO3(BST)-based ER fluids. The shear stress of the BSTU (doped with 3 wt.% urea) based ER fluids (with a volume fraction of 30%) reaches 17.2 kPa at E = 4 kV/mm.