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Liu J.-Q.,Hefei University of Technology | Liu J.-Q.,Anhui Key Laboratory of Advanced Functional Materials and Devices | Wu Y.-C.,Anhui Key Laboratory of Advanced Functional Materials and Devices
Wuji Cailiao Xuebao/Journal of Inorganic Materials | Year: 2015

Bismuth-based semiconductor of BiOX (X=Cl, Br, I) has proved to be a new promising photocatalytic material due to its unique layered crystal structure and suitable band gaps, which exhibits superior photocatalytic performance and high stability. In this review, some key scientific topics in terms of photocatalysis of BiOX (X=Cl, Br, I) were firstly addressed, then the effective modification methods were comprehensively summarized, including microstructure adjustment, heterojunction construction, noble-metal deposition, doping, surface sensitization, etc. In addition, the research progress in catalyst immobilization by loading nano-structured BiOX (X=Cl, Br, I) onto appropriate carriers were also reviewed. Generally, this review presents the most recent advances of high performance of the BiOX (X=Cl, Br, I) based photocatalysts in depth and also prospects the research trend of the BiOX (X=Cl, Br, I) catalyst. ©, 2015, Science Press. All right reserved.

Yan W.-Y.,Hefei University of Technology | Zhou Q.,Hefei University of Technology | Chen X.,Hefei University of Technology | Chen X.,Chinese Academy of Sciences | And 5 more authors.
Journal of Hazardous Materials | Year: 2016

Photocatalytic degradation is one of the most promising methods for removal of fulvic acids (FA), which is a typical category of natural organic contamination in groundwater. In this paper, TiO2/graphene nanocomposites (N-RGO/TiO2) were prepared via simple chemical functionalization and one-step hydrothermal method for efficient photodegradation of FA under illumination of a xenon lamp as light source. Here, p-phenylenediamine was used as not only the linkage chemical agent between TiO2 nanocrystals and graphene, but also the nitrogen dopant for TiO2 nanocrystals and graphene. During the hydrothermal process, facets of TiO2 nanocrystals were modulated with addition of HF, and sizes of TiO2 nanocrystals were controlled by the contents of graphene oxide functionalized with p-phenylenediamine (RGO-NH2). The obtained N-RGO/TiO2 nanocomposites exhibited a much higher photocatalytic activity and stability for degradation of methyl blue (MB) and FA compared with other TiO2 samples under xenon lamp irradiation. For the third cycle, the 10wt%N-RGO/TiO2 catalyst maintains high photoactivity (87%) for the degradation of FA, which is much better than the TiO2-N/F (61%) in 3 h. This approach supplies a new strategy to design and synthesize metal oxide and graphene oxide nanocomposites with highly efficient photocatalytic performance. © 2016 Elsevier B.V.

Zhong Y.-H.,Hefei University of Technology | Zhong Y.-H.,Anhui Key Laboratory of Advanced Functional Materials and Devices | Zhou Q.,Hefei University of Technology | Liu J.-Q.,Hefei University of Technology | And 6 more authors.
Chinese Journal of Inorganic Chemistry | Year: 2013

Using tetrabutyl orthotitanate as Ti source, hydrofluoric acid as F source and ethanol as solvent, well crystallized anatase-phase F-modified TiO2 hollow microspheres have been synthesized via a solvothermal process. The structure and properties of the resulting samples were characterized by XRD, SEM, FTIR, XPS. The results indicated that the fluorizated TiO2 hollow microspheres had an anatase phase, the fluorine atoms were mainly distributed on the surface of TiO2, and existed in forms of chemical-adsorption. Hollow anatase TiO2 microspheres were achieved by stwald ripening under solvothermal conditions. Compared to pure titania, the fluorizated TiO2 hollow microspheres showed a much higher degradation efficiency, and degradation rate of which can be up to 98 during the photodegradation of methyl orange with the initial concentration of 20 mg · L-1 for 30 minutes. The mechanism for the great improvement for photocatalytic activity can be attributed to the unique structure of hollow microsphere and the fluorine modification, because the strong electron withdrawing ability of the surface ≡ Ti-F groups reduces the recombination of photogenerated electrons and holes, and enhances the formation of free OH radicals.

Liu J.,Hefei University of Technology | Liu J.,Anhui Key Laboratory of Advanced Functional Materials and Devices | Ruan L.,Hefei University of Technology | Adeloju S.B.,Monash University | And 2 more authors.
Dalton Transactions | Year: 2014

A series of unique flake-tube structured p-n heterojunctions of BiOI/TiO2 nanotube arrays (TNTAs) were successfully prepared by loading large amounts of BiOI nanoflakes onto both the outer and inner walls of well-separated TiO2 nanotubes using anodization followed by the sequential chemical bath deposition (S-CBD) method. The as-prepared BiOI/TNTAs samples were characterized by X-ray diffraction, electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy and nitrogen sorption. The photoelectrocatalytic (PEC) activity and stability of the BiOI/TNTAs samples toward degradation of methyl orange (MO) solutions under visible-light irradiation (λ > 420 nm) were evaluated. The visible-light PEC performance of BiOI/TNTAs samples was further confirmed by the transient photocurrent response test. The results from the current study revealed that the 5-BiOI/TNTAs sample exhibited the best PEC activity, favourable stability, and the highest photocurrent density among all the BiOI/TNTAs heterostructured samples. The combined effects of several factors may contribute to the remarkable visible-light PEC performance for the 5-BiOI/TNTAs sample including a 3D connected intertube spacing system and an open tube-mouth structure, strong visible-light absorption by BiOI, the formation of a p-n junction, larger specific surface area, and the impact of the applied external electrostatic field. This journal is © The Royal Society of Chemistry.

Yan W.-Y.,Hefei University of Technology | Zhou Q.,Hefei University of Technology | Chen X.,Hefei University of Technology | Chen X.,Chinese Academy of Sciences | And 3 more authors.
Sensors and Actuators, B: Chemical | Year: 2016

Element doping and controllably facet exposing are efficient solutions for enhancing gas sensing performances of TiO2 nanomaterials. In this study, C-doped and N-doped reduced graphene oxide/TiO2 composites with special exposed facets C-RGO/TiO2 (with HF) and N-RGO/TiO2 (with HF) were controllably synthesized via a hydrothermal method using HF as the morphology-controlling agent at 180°C for 12 h. The as-prepared composites were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and other measurements. Their gas sensing results demonstrate that the gas sensing performance of N-RGO/TiO2 (with HF) is much better than that of C-RGO/TiO2 (with HF), such as higher sensitivity, and shorter response and recovery time. The sensor based on N-RGO/TiO2 (with HF) exhibits the highest gas response toward isopropanol, ethanol, and acetone at a working temperature of 210, 240, and 270°C, respectively. The lowest detection of these gases was 1 ppm. The gas sensing mechanism was also carefully analyzed. The TiO2 particles of composite with exposed facets generate electron-hole pairs efficiently. The N element dopant plays the roles of narrowing the band gap of TiO2 based composite, and strengthening the chemical binding between N-RGO and TiO2, which is of benefit to charge separation and electron mobility. © 2016 Elsevier B.V.

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