W-Ag共掺杂SrTiO_(3)的制备及其光催化性能

Preparation and photocatalytic properties of W-Ag co-doped SrTiO_(3)

本研究采用溶胶-凝胶法制备W-Ag共掺杂SrTiO_(3),以亚甲基蓝(MB)为目标污染物,研究W-Ag共掺杂SrTiO_(3)的光催化活性及其效率提升的机制.通过X射线衍射(XRD)、扫描电镜(SEM)、光致发光光谱分析(PL)、紫外-可见漫反射光谱(UV-vis DRS)、比表面积测试(BET)和X射线光电子能谱(XPS)对样品结构、组成和光学性能进行表征.结果表明,W和Ag成功掺入SrTiO_(3)晶体结构中,并引起SrTiO_(3)产生晶格畸变,粒径尺寸减小.相比纯SrTiO_(3)比表面积15.200 m^(2)·g^(-1),W-Ag共掺杂SrTiO_(3)比表面积增大到16.523 m^(2)·g^(-1),有利于活性位点的暴露. W和Ag的掺杂增加了SrTiO_(3)晶格内氧空位和表面吸附氧含量,有效抑制电子-空穴对的复合.此外,在SrTiO_(3)价带上方产生了缺陷能级,提高SrTiO_(3)的可见光响应.因此,与纯SrTiO_(3)相比,W-Ag共掺杂SrTiO_(3)显示出了更强的光催化活性.在模拟太阳光条件下,相比纯SrTiO_(3)在6 h内54.8%的降解效率,W-Ag共掺杂SrTiO_(3)的降解效率可达到90.5%,而降解速率常数由0.0861 h-1增加到0.3895 h-1,几乎是纯SrTiO_(3)的5倍.

In this paper, the novel W-Ag co-doped SrTiO_(3)samples were prepared by sol-gel method, the photocatalytic activity has been investigated for methylene blue degradation. Structure,composition and morphology of the as-prepared catalysts were characterized using several techniques including X-ray diffraction(XRD)、 Scanning electron microscope(SEM)、 Photoluminescence spectroscopy(PL)、Uv-visible diffuse reflectance(UV-vis DRS)、Specific surface area(BET) and X-ray photoelectron spectroscopy(XPS). The results show that the successful doping of W and Ag into SrTiO_(3)crystal lattice was achieved, and the dopants, and the distortion of SrTiO_(3)crystal lattice caused by doping resulted in the decrease of crystallite size of SrTiO_(3). W-Ag co-doped SrTiO_(3)sample has a surface area of about 16.523 m^(2)·g^(-1), which is larger than that of pure SrTiO_(3)(15.200 m^(2)·g^(-1)). The relatively large specific surface area of W-Ag co-doped SrTiO_(3)sample provides a greater number of reactive sites for the photocatalytic process. Doping of W and Ag increases the oxygen vacancy concentration and surface absorbed oxygen, which suppress recombination rate of the photogenerated electron-hole pairs. Besides, the defect energy level is generated above valence band of SrTiO_(3), which improves its visible light response. So, W-Ag co-doped SrTiO_(3)show higher photocatalytic activity compared with pure SrTiO_(3). The photocatalytic degradation efficiency of WAg co-doped SrTiO_(3)to MB reaches 90.5% after 6 h under the simulated sunlight illumination, much higher than that of pure SrTiO_(3)(54.8%), and the degradation rate constant of MB for W-Ag co-doped SrTiO_(3)is 0.3895 h-1, which was almost 5 times as much as pure SrTiO_(3).