2D/3D ZnIn_(2)S4/TiO_(2)复合物的原位构筑及其提高的光催化性能

In-situ Construction of 2D/3D Zn In_(2)S_(4)/TiO_(2)with Enhanced Photocatalytic Performance

通过高温煅烧和油浴的方法构筑二维/三维(2D/3D)ZnIn_(2)S_(4)/TiO_(2)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TiO_(2)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,TiO_(2)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ZnIn_(2)S_(4)纳米片复合后,TiO_(2)的比表面积增大,光催化活性位点增多.带隙宽度也由TiO_(2)的3.23 eV减小到ZnIn_(2)S_(4)/TiO_(2)-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ZnIn_(2)S_(4)/TiO_(2)是typeⅡ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,ZnIn_(2)S_(4)/TiO_(2)-Ⅱ显示了最高的RhB光催化降解效率(93%),分别是TiO_(2)和ZnIn_(2)S_(4)的18和2倍.同时,ZnIn_(2)S_(4)/TiO_(2)-Ⅱ也显示出比TiO_(2)和ZnIn_(2)S_(4)更高的TC降解效率(90%).循环实验表明ZnIn_(2)S_(4)/TiO_(2)-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TiO_(2)构筑2D/3D ZnIn_(2)S_(4)/TiO_(2)异质结是提高TiO_(2)光催化性能的一条有效途径.

To study the influence of the construction of heterojunction on the visible-light response range and the photo-generated charge carriers separation efficiency of TiO_(2),two dimensional/three dimensional(2D/3D)ZnIn_(2)S_(4)/TiO_(2)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 TiO_(2)maintains the morphology of metal-organic frameworks(MOFs)with narrow visible-light response range and high photo-generated charge recombination efficiency.After coupling with ZnIn_(2)S_(4)nano sheets,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 TiO_(2)to2.52 eV of ZnIn_(2)S_(4)/TiO_(2)-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 typeⅡheterojunction in the ZnIn_(2)S_(4)/TiO_(2)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,ZnIn_(2)S_(4)/TiO_(2)displayed significantly enhanced photocatalytic activity than bare TiO_(2)and ZnIn_(2)S_(4).Among of ZnIn_(2)S_(4)/TiO_(2)photocatalysts,ZnIn_(2)S_(4)/TiO_(2)-Ⅱpossessed the highest photocatalytic degradation efficiency(93%)of RhB solution within 60 min,which was nearly 18 and 2 times higher than pristine TiO_(2)and ZnIn_(2)S_(4),respectively.Besides,the ZnIn_(2)S_(4)/TiO_(2)-Ⅱphotocatalyst also showed enhanced photocatalytic activity for TC degradation than pure TiO_(2)and ZnIn_(2)S_(4).The cycle experiment showed that the ZnIn_(2)S_(4)/TiO_(2)-Ⅱphotocatalyst could maintain good reusability,and it could still photodegrade 83%RhB after 5-cycle test.This work demonstrates that constructing 2D/3D ZnIn_(2)S_(4)/TiO_(2)heterojunction based on MOFs-derived TiO_(2)is an efficient strategy for significantly enhancing the photocatalytic activity of TiO_(2).