Jin Mao,Qi Zhang,Peiwu Li,Liangxiao Zhang,Wen Zhang
Geometric architecture of composite photocatalytic system creates a favorable chance for enhanced photocatalytic activity, which is a challenging and rewarding direction in this area. Here, a novel and highly efficient three-components composite consisting of dispersive WO 3 nanowires, g-C 3 N 4 nanosheets and RGO as solid electron mediator was successfully designed, synthesized and characterized. The WO 3 /RGO/g-C 3 N 4 composite exhibited markedly enhanced activity for the photocatalytic degradation of aflatoxin B 1 under visible-light irradiation compared with single and binary catalysts. It was found that the synergistic effects coexisted in this ternary composites that depended on the geometric architecture and interface combination of components. The Z-scheme system formed when RGO was as an interlayer between WO 3 and g-C 3 N 4 , while the mechanism was the heterojunction-type in absence of RGO. It was found that the O 2 − , h + and OH were main active radicals during photodegradation of AFB 1 over ternary composites, which was proved by the radical trapping tests and ESR detection. Finally, a probable enhanced photocatalytic degradation mechanism of ternary composites and the degradation products were also proposed. This work may not only provide beneficial information to design and synthesis of effective composites system, but also present a new way to remove the refractory natural pollutant.
Jun Zhang,Jiang-ping Tu,Xin-hui Xia,Xiu-li Wang,Chang-dong Gu
A hexagonal WO3 nanowire array film is obtained using a template-free hydrothermal method by adding ammonium sulfate as a capping agent. The WO3 nanowires grown vertically on a FTO-coated glass substrate are woven together at the surface of the film, forming well-aligned arrays at the bottom part and a porous surface morphology. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) reveal that each nanowire is a hexagonal single crystal and their long axes are oriented toward the [0001] direction. Due to the highly porous surface, good contact with the conductive substrate and large tunnels of the hexagonal-structured WO3, a fast switching speed of 7.6 and 4.2 s for coloration and bleaching, respectively, and a high coloration efficiency of 102.8 cm2C−1 are achieved for the WO3 nanowire array film.
The demand for advanced energy storage devices such as supercapacitors and lithium-ion batteries has been increasing to meet the application requirements of hybrid vehicles and renewable energy systems. Here, high energy density aqueous asymmetric supercapacitor (ASC) is assembled based on chestnut shell-based activated carbon (CAC)/PANI composite positive electrode and tungsten trioxide (WO 3 ) nanowires negative electrode. The CAC/PANI composite and WO 3 nanowires were synthesized through an interfacial polymerization method and a simple sodium sulfate assisted hydrothermal process, respectively. The CAC/PANI//WO 3 ASC device operates with a voltage of 1.5 V in 1 M H 2 SO 4 electrolyte and achieved a high energy density of 15.4 Wh kg −1 at a power density of 252 W kg −1 . Furthermore, the device shows an excellent cycling performance with capacitance retention of 83% after 1500 cycles.
The oxidative desulfurization (ODS) of fuel oils is of great significance for environmental protection, and the development of efficient ODS heterogeneous catalysts is highly desired. Herein, we have designed and synthesized a novel material of amorphous Cr2WO6-modified WO3 (a-Cr2WO6/WO3) nanowires (3–6 nm) with a large specific surface area of 289.5 m2·g–1 and rich Lewis acid sites. The formation of such a unique nanowire is attributed to the adsorption of Cr3+ cations on non-(001) planes of WO3. In the ODS process, the a-Cr2WO6/WO3 nanowires can efficiently oxidize benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) to their corresponding sulfones in a quasi-microemulsion reaction system and possess the highest activity (Ea = 55.4 kJ/mol) for DBT: 99.0% of 15,000 ppm DBT with 2600 ppm S can be removed (70 °C, H2O2 as the oxidant). The improvement in ODS activity from most of WO3 catalysts is owing to the sufficient active sites and enhanced adsorption of DBT on the basis of structural features of a-Cr2WO6/WO3 nanowires. Combined with free radical capture experiments, a possible ODS mechanism of W(O2) peroxotungstate route based on surface −OH groups is reasonably proposed. Moreover, the a-Cr2WO6/WO3 nanowires have good stability and can be synthesized on a large scale, suggesting its potential applications as an efficient heterogeneous catalyst.
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