摘要/Abstract

通过高温煅烧和油浴的方法构筑二维/三维(2D/3D) ZnIn₂S₄/TiO₂异质结, 应用于光催化降解罗丹明B (RhB)和四环素(TC), 来研究异质结的构筑对TiO₂可见光响应范围和光生载流子对分离效率的影响. 结果表明, TiO₂维持了MOFs的形貌, 显示窄的可见光响应范围和高的光生电荷复合率, 与ZnIn₂S₄纳米片复合后, TiO₂的比表面积增大, 光催化活性位点增多. 带隙宽度也由TiO₂的3.23 eV减小到ZnIn₂S₄/TiO₂-II的2.52 eV, 从而获得了更宽的可见光响应范围. 能带结构表明ZnIn₂S₄/TiO₂是type II型异质结, 提高了光生载流子对的分离与转移效率. 在可见光照射下, ZnIn₂S₄/TiO₂-II显示了最高的RhB光催化降解效率(93%), 分别是TiO₂和ZnIn₂S₄的18和2倍. 同时, ZnIn₂S₄/TiO₂-II也显示出比TiO₂和ZnIn₂S₄更高的TC降解效率(90%). 循环实验表明ZnIn₂S₄/TiO₂-II能保持良好的稳定性, 经5次循环实验后仍能降解83%的RhB. 研究表明基于MOFs衍生的TiO₂构筑2D/3D ZnIn₂S₄/TiO₂异质结是提高TiO₂光催化性能的一条有效途径.
关键词: 光催化, 二氧化钛, 金属有机框架材料, 异质结, 可见光响应
To study the influence of the construction of heterojunction on the visible-light response range and the photo-generated charge carriers separation efficiency of TiO₂, two dimensional/three dimensional (2D/3D) ZnIn₂S₄/TiO₂ heterojunctions were synthesized by high-temperature calcination followed by a facile oil bath method, and were investigated for the photodegradation of Rhodamine B (RhB) and tetracycline (TC). X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were applied to investigate the composition, crystal structure, and morphology of the as-prepared specimens. UV-visible diffuse reflectance spectra (UV-vis DRS), electrochemical impedance spectroscopy (EIS), photocurrent measurement, photoluminescence (PL) spectra, and first-principles calculation were also performed to investigate the photoelectric property. The results showed TiO₂ maintains the morphology of metal-organic frameworks (MOFs) with narrow visible-light response range and high photo-generated charge recombination efficiency. After coupling with ZnIn₂S₄ nanosheets, a larger specific surface area was obtained with offering more active sites for photocatalytic reaction. The band gap of the composite was reduced from 3.23 eV of TiO₂ to 2.52 eV of ZnIn₂S₄/TiO₂-II, and thus obtaining an extended visible-light response range and enhancing visible light utilization rate. The energy band structure acquired from the UV-vis DRS and XPS valence band spectra indicated a construction of type II heterojunction in the ZnIn₂S₄/TiO₂ composite, and thus improving the separation and transfer efficiency of photo-generated carrier pairs, which was confirmed by the PL, EIS and photocurrent test results. Under the visible light, ZnIn₂S₄/TiO₂ displayed significantly enhanced photocatalytic activity than bare TiO₂ and ZnIn₂S₄. Among of ZnIn₂S₄/TiO₂ photocatalysts, ZnIn₂S₄/TiO₂-II possessed the highest photocatalytic degradation efficiency (93%) of RhB solution within 60 min, which was nearly 18 and 2 times higher than pristine TiO₂ and ZnIn₂S₄, respectively. Besides, the ZnIn₂S₄/TiO₂-II photocatalyst also showed enhanced photocatalytic activity for TC degradation than pure TiO₂ and ZnIn₂S₄. The cycle experiment showed that the ZnIn₂S₄/TiO₂-II photocatalyst could maintain good reusability, and it could still photodegrade 83% RhB after 5-cycle test. This work demonstrates that constructing 2D/3D ZnIn₂S₄/TiO₂ heterojunction based on MOFs-derived TiO₂ is an efficient strategy for significantly enhancing the photocatalytic activity of TiO₂.
Key words: photocatalysis, titanium dioxide, metal-organic frameworks, heterojunction, visible-light response


PDF全文下载地址:

点我下载PDF