Adepu Ajay Kumar, Goskula Srinath, Chirra Suman, Siliveri Suresh, Gujjula Sripal Reddy, Narayanan Venkatathri
Department of Chemistry, National Institute of Technology Warangal 506 004 Telangana India
RSC Adv. 2019 Aug 6;9(42):24368-24376. doi: 10.1039/c9ra03866c. eCollection 2019 Aug 2.
In the present study, we synthesized several high-surface area VO/TiO-SiO catalysts (vanado titanium silicate, VTS). The synthesized materials were characterized by PXRD, FE-SEM/EDAX, TEM, FTIR, UV-Vis, XPS, fluorescence and photocatalytic activity studies. The small-angle powder X-ray diffraction pattern shows that the 110 and 200 planes are merged to become a single broad peak. Field-emission scanning electron microscopy shows that the titanosilicate is spherical in shape and VO has a hexagonal rod-shaped morphology. The presence of various metal ions, such as V, Ti, Si and O, was observed by energy dispersive X-ray analysis and X-ray photoelectron spectroscopy. The transmission electron microscopy image shows clear hexagonal mesoporous fringes with VO distribution. The BET surface area analysis shows that the VTS catalysts have higher surface areas than pure VO. Fourier transform infrared spectroscopic analysis shows the presence of Ti ions connected to the silanol groups. The bandwidths of pure titanosilicate, VO and their composites were calculated from their diffuse reflectance ultraviolet-visible spectra. The bandwidth was tuned by heterojunctions in the studied catalysts. The photoluminescence spectra of the VTS catalysts show a distinct behaviour as compared to those of the pure components. The photocatalytic activity of methylene blue degradation was determined with pure constituents and catalysts. VTS-1 (TS and VO weight ratio 2 : 1) shows higher conversion than other catalysts, pure titanosilicate and VO. This is probably due to the heterojunctions and higher surface area in VTS-1. Kinetic studies reveal that direct sunlight shows higher activity than pure visible light. A plausible physical and chemical mechanism for the photocatalytic activity is proposed.
在本研究中，我们合成了几种高比表面积的VO/TiO-SiO催化剂（钒钛硅酸盐，VTS）。通过粉末X射线衍射（PXRD）、场发射扫描电子显微镜/能谱分析（FE-SEM/EDAX）、透射电子显微镜（TEM）、傅里叶变换红外光谱（FTIR）、紫外-可见光谱（UV-Vis）、X射线光电子能谱（XPS）、荧光和光催化活性研究对合成材料进行了表征。小角粉末X射线衍射图谱表明，110和200晶面合并成一个单一的宽峰。场发射扫描电子显微镜表明，钛硅酸盐呈球形，VO具有六方棒状形态。通过能量色散X射线分析和X射线光电子能谱观察到了各种金属离子（如V、Ti、Si和O）的存在。透射电子显微镜图像显示出清晰的六方介孔条纹以及VO的分布。BET比表面积分析表明，VTS催化剂的比表面积高于纯VO。傅里叶变换红外光谱分析表明存在与硅醇基团相连的Ti离子。根据其漫反射紫外-可见光谱计算了纯钛硅酸盐、VO及其复合材料的带宽。通过研究催化剂中的异质结来调节带宽。与纯组分相比，VTS催化剂的光致发光光谱表现出明显不同的行为。用纯组分和催化剂测定了亚甲基蓝降解的光催化活性。VTS-1（TS与VO重量比为2∶1）显示出比其他催化剂、纯钛硅酸盐和VO更高的转化率。这可能是由于VTS-1中的异质结和更高的比表面积。动力学研究表明，直射阳光的活性高于纯可见光。提出了一种合理的光催化活性物理和化学机理。
