可见光响应SO2－4／Ce-TiO2的光谱特征及催化性能

采用溶胶‐凝胶法制备了Ce掺杂 T iO2，经 H2 SO4处理得到酸化Ce掺杂 T iO2。利用X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、吡啶吸附红外光谱（Py‐FTIR）、紫外‐可见光漫反射光谱（UV‐Vis）及X射线光电子能谱（XPS）技术对样品的性质进行了表征，以罗丹明B（RhB）在样品上的可见光催化降解为模型反应，评价了所制备样品的光催化性能。XRD测试结果表明，铈掺杂使 TiO2产生晶格缺陷、粒径减小，有利于光生电荷的转移，继而提高催化剂的活性；FTIR谱图说明SO2－4以桥式双齿配位吸附形式存在；Py‐FTIR谱图显示，酸化铈掺杂TiO2样品表面同时存在Br?nsted和Lewis酸位，但以Lewis酸为主。Lewis酸中心的缺电子性质有利于样品表面的光生电子与光生空穴分离，从而改善催化剂的活性；UV‐Vis结果表明，Ce掺杂减小了TiO2的带隙能，引入的杂能级能够捕获导带上的光生电子和价带上的光生空穴，降低光生电子‐空穴对的复合几率；同时还可以使能量较小的光子激发杂能级上捕获的电子，拓宽光响应范围；XPS分析表明SO2－4／Ce‐TiO2样品上同时存在Ce3＋／Ce4＋的混合价态，Ce3＋／Ce4＋氧化‐还原转换有助于TiO2受光激发后产生的光生电子和空穴的分离，从而提高光量子效率。酸化Ce掺杂TiO2对RhB的可见光催化降解反应有很好的活性，实验结果证明，H2 SO4酸化和Ce掺杂的协同作用改善了样品的可见光响应，促进了其可见光催化反应活性。

Spectral Characteristics and Catalytic Performances of SO 2-4/Ce-TiO2 with Visible Light Response

Ce doped TiO2 was prepared via sol‐gel method .The as‐prepared Ce doped TiO2 was impregnated with diluted H2SO4 to obtain a H2 SO4‐treated Ce doped TiO2 .In succession ,the characterizations of X‐ray diffraction (XRD) ,Fourier transform infrared spectroscopy (FTIR) ,pyridine adsorption‐FTIR (Py‐FTIR) ,ultraviolet‐visible spectroscopy (UV‐vis) and X‐ray pho‐toelectron spectroscopy (XPS) were carried out to analyze the reasons for the improvement of the light response performance . The visible light photocatalytic degradation of Rhodamine B (RhB) in an aqueous solution was used as a probe reaction to evalu‐ate the photocatalytic activity of the obtained samples .According to the XRD analysis ,Ce doping created the lattice defects in TiO2 and minimized the particle size ,which promoted the transfer of photo‐generated electrons and then improved catalyst activi‐ty .The bridged bidentate coordination mode of SO2 -4 was proposed based on the FTIR spectra .The pyridine FTIR spectra showed that both Lewis and Br?nsted acid sites were formed on the sample surface .The characteristic absorption band as Lewis acid was more intense than that of the Br?nsted acid ,exhibiting the major Lewis acidity .The presence of the Lewis acid sites re‐sulted in the transfer of photogenerated electrons to the Lewis acid center because of the electron deficiency of the Lewis acid sites ,which contributed greatly to the transport of the photogenerated electrons ,inhibiting the recombination of the photogener‐ated electron/hole pairs and leading to the enhancement of the photocatalytic activity of samples .From UV‐Vis results ,Ce‐do‐ping introduced an impurity energy level in the band gap ,narrowing the TiO2 band gap .The impurity energy level could capture the photogenerated electrons on the conduct band and photogenerated holes on the valence band ,reducing the recombination probability of photogenerated carriers and exciting the electrons captured on the impurity energy band by the photons with lower energy ,thus expanding the light response range of TiO2 .The XPS results indicated that the doped Ce existed as a mixture of Ce3+ /Ce4+ states ,which facilitated the efficient separation of the photo‐generated electrons and holes because of the electron transfer ,enhancing the system’s quantum efficiency .The sulfated Ce doped TiO2 catalysts were very active for the visible pho‐tocatalytic degradation of RhB .Results showed that the synergetic effects of Ce doping and acid‐treatment improved the visible light response for sulfated Ce‐doped TiO2 ,enhancing the visible photocatalytic activity .