Fabrication of a monoclinic/hexagonal junction in WO3 and its enhanced photocatalytic degradation of rhodamine B
Fabrication of a monoclinic/hexagonal junction in WO3 and its enhanced photocatalytic degradation of rhodamine B
复制标题
WO3 中单斜/六方结的制备及其增强的罗丹明 B 光催化降解
DOI：
10.1016/s1872-2067(15)61023-3
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发表时间：
2016-03-01
影响因子：
16.5
通讯作者：
Li, Zhi
中科院分区：
文献类型：
--
作者：
Lu, Yuanyuan;Liu, Guo;Li, Zhi
以水合钨酸铵为原料，采用热分解法制备了一系列不同晶相的WO 3样品。采用X射线衍射（XRD）、扫描电子显微镜（SEM）、高分辨透射电子显微镜（HRTEM）、X射线光电子能谱（XPS）和N-2吸附-脱附等手段对样品的晶相、形貌、粒径、化学组成和比表面积进行了表征。XRD分析表明，在不同温度和不同时间下，WO 3分别形成了六方（h-WO 3）和单斜（m-WO 3）晶体结构。m-WO 3在600 ℃形成，而m-WO 3在800 ℃开始转化为h-WO 3。然而，在800 ℃下形成的h-WO 3可以通过将煅烧温度提高到1000 ℃而转化为m-WO 3。SEM结果表明，m-WO 3颗粒表现出笨重的形状与重聚集体，而h-WO 3颗粒表现出棒状形状。此外，m-WO 3晶体零星地修补在h-WO 3棒状颗粒的表面上，导致m-WO 3和h-WO 3都暴露在表面上。通过调节煅烧温度和煅烧时间，可以制备出单斜相（m-WO 3）/六方相（h-WO 3）结。相结中m-WO 3和h-WO 3之间的相对比率可以容易地通过控制煅烧时间来定制。以罗丹明B为模型污染物，考察了不同晶相的WO 3的光催化活性。具有m-WO 3/h-WO 3结的WO 3样品比仅具有m-WO 3的样品具有更高的光催化活性。光催化活性的提高可以归因于由于相结的形成而降低的电子-空穴复合速率，其存在已被HRTEM和光致发光光谱证实。(C)2016年，中国科学院大连化学物理研究所。Elsevier B. V.出版，保留所有权利。
A series of WO3 samples with different crystalline phases were prepared by the thermal decomposition method from ammonium tungstate hydrate. X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy, and N-2 adsorption-desorption were used to characterize the crystalline phase, morphology, particle size, chemical composition, and surface area of the WO3 samples. The formation of hexagonal (h-WO3) and monoclinic (m-WO3) crystal structures of WO3 at different temperatures or different times was confirmed by XRD. m-WO3 is formed at 600 degrees C, while m-WO3 starts to transform into h-WO3 at 800 degrees C. However, h-WO3, which forms at 800 degrees C, may transform into m-WO3 by increasing the calcination temperature to 1000 degrees C. SEM results indicate that m-WO3 particles exhibit a bulky shape with heavy aggregates, while h-WO3 particles exhibit a rod-like shape. Moreover, m-WO3 crystals are sporadically patched on the surface of the h-WO3 rod-like particles, resulting in the exposure of both m-WO3 and h-WO3 on the surface. It is observed that the monoclinic phase (m-WO3)/hexagonal phase (h-WO3) junction was fabricated by tuning the calcination temperature and calcination time. The relative ratios between m-WO3 and h-WO3 in the phase junction can readily be tailored by control of the calcination time. The photocatalytic activities of WO3 with different crystalline phases were evaluated by the photocatalytic degradation of rhodamine B as a model pollutant. A higher photocatalytic activity was observed in the WO3 sample with the m-WO3/h-WO3 junction as compared with the sample with only m-WO3. The improvement of photocatalytic activity can be attributed to the reduction of the electron-hole recombination rate owing to the formation of the phase junction, whose presence has been confirmed by HRTEM and photoluminescence spectra. (C) 2016, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.