Tungsten oxide (WO3) and boron oxide (B2O3) were irreversibly encapsulated into the nanocages of the Zr-based metal organic framework UiO-66, affording a hybrid material B2O3-WO3/UiO-66 by a simple microwave-assisted deposition method. The novel B2O3-WO3/UiO-66 material was systematically characterized by X-ray diffraction, Fourier transform infrared spectroscopy, N2adsorption, ultraviolet–visible diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray phosphorescence, and Fourier transform infrared (FTIR)-CO adsorption methods. It was found that WO3and B2O3were highly dispersed in the nanocages of UiO-66, and the morphology and crystal structure of UiO-66 were well preserved. The B2O3species are wrapped by WO3species, thus increasing the polymeric degree of the WO3species, which are mainly located in low-condensed oligomeric environments. Moreover, when compared with WO3/UiO-66, the B2O3-WO3/UiO-66 material has a little weaker acidity, which decreased by 10% upon the B2O3introduction. The as-obtained novel material exhibits higher catalytic performance in the cyclopentene selective oxidation to glutaraldehyde than WO3/UiO-66. The high catalytic performance was attributed to a proper amount of B2O3and WO3with an appropriate acidity, their high dispersion, and the synergistic effects between them. In addition, these oxide species hardly leached in the reaction solution, endowing the catalyst with a good stability. The catalyst could be used for six reaction cycles without an obvious loss of catalytic activity.Keywords:UiO-66;WO3;B2O3;metal organic frameworks;cyclopentene;glutaraldehyde
A novel nanocomposite (WO 3 /UiO-66) was successfully synthesized by the microwave hydrothermal method. The influence of the W:Zr molar ratio on the WO 3 /UiO-66 structure was explored in detail, and the photocatalytic activity of the nanocomposite for photodegradation of rhodamine B (RhB) was evaluated. The WO 3 /UiO-66 with a W:Zr molar ratio of 1:5 (WO 3 /UiO-66–5) exerted the most excellent photocatalytic performance, and the photocatalytic efficiency reached 96.6% after 100 min of simulated sunlight irradiation, thereby showing a higher photocatalytic performance than pure UiO-66 or pure WO 3 . In addition, the stability and reusability of the nanocomposite were studied by cyclic experiments, and the degradation rate of WO 3 /UiO-66–5 still reached 86.6% after 5 cycles. The mechanism underlying the photocatalytic degradation of WO 3 /UiO-66 was finally studied by quenching tests, and the crucial factor in the RhB degradation was hole (h + ), and the existence of the n–n heterojunction also promotes the degradation of RhB by nanocomposites. In this work, an effective method is provided for the preparation of photocatalysts that degrade organic dyes.
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