铂非均匀掺杂二氧化钛薄膜的光催化性能

采用溶胶-凝胶法制备了铂非均匀掺杂的二氧化钛薄膜, 并用UV-vis分光光度计及电化学工作站表征了薄膜的光吸收性能和光电化学行为, 通过对甲基橙的光催化降解动力学来表征催化剂的光催化活性. 结果表明 Pt非均匀掺杂可以明显增强二氧化钛的光催化活性, 而均匀掺杂的效果较差; Pt非均匀掺杂的最佳量为0.3 mol%. 催化剂薄膜的电化学行为显示: Pt非均匀掺杂二氧化钛薄膜的开路电压高, 交流阻抗小. 并从半导体的PN结原理探讨了Pt非均匀掺杂二氧化钛的催化活性机理.     

稀土元素掺杂对TiO2薄膜光催化性能的影响

采用Sol-Gel法、浸渍-提拉法制备了RE(Sm, Dy, Lu) 掺杂TiO2的锐钛矿晶型薄膜. 用X射线衍射分析、 UV-Vis透射光谱及电化学实验对其进行了表征, 通过对紫外光照射下甲基橙溶液的光催化降解评价了其光催化性能. 结果表明, RE掺杂的TiO2薄膜的吸收光向长波方向移动; 掺杂浓度是影响光催化活性的重要因素; 适量RE掺杂可以明显提高TiO2薄膜的光催化性能; 最佳掺杂浓度是0.5%. 其中掺杂Sm样品的光催化活性最好. 分别讨论了RE不同浓度及不同元素掺杂对TiO2光催化性能的影响机制.     

Sm掺杂对TiO2薄膜光催化性能的影响

 采用溶胶-凝胶法、浸渍-提拉法制备了不同形式和不同含量Sm掺杂的锐钛矿晶型TiO2的光催化剂薄膜. 采用X射线衍射、UV-Vis光谱及电化学实验对所制得的TiO2光催化剂薄膜进行了表征,并通过甲基橙溶液的光催化降解实验评价了其光催化活性. 结果表明,与未掺杂的TiO2薄膜相比,Sm掺杂的TiO2薄膜的UV-Vis吸收光波长向长波方向移动,并且光照开路电压也相应提高; 适量Sm掺杂可以明显提高TiO2薄膜的光催化活性,最佳Sm掺杂量为x(Sm3+)=0.5%; 在各种掺杂形式中以表层Sm掺杂的Sm-TiO2(S)薄膜的光催化活性最好. 讨论了Sm掺杂提高TiO2薄膜光催化活性的机理.     

钒离子掺杂对TiO2光催化剂薄膜催化活性的影响

采用溶胶凝胶工艺在普通玻璃表面制备了钒离子非均匀掺杂的TiO2薄膜,运用XRD研究了其光催化复合薄膜的表面特征.以光催化降解甲基橙溶液为模型反应,表征薄膜的光催化活性,结果表明,将钒离子富集在TiO2薄膜内部时,最佳掺杂浓度为1.0%(V/Ti原子百分比),最佳降解表观速率常数为7.44×10-3min-1,约是纯TiO2的2.3倍,有效地提高了TiO2半导体的光催化效率.通过XPS与电化学方法进行分析,说明将钒离子富集在TiO2薄膜内部十分有利于电子-空穴的分离,增强了光生电子与空穴的分离效率.     

Ni控制掺杂TiO2薄膜的光电化学及光催化活性

采用溶胶-凝胶法通过分步控制工艺制备了镍离子不同掺杂方式的TiO₂薄膜。通过甲基橙的光催化降解动力学来表征其光催化活性。结果表明：镍离子非均匀掺杂在掺杂量0.5%时可以明显增强TiO₂的光催化活性，而均匀掺杂提高TiO₂的光催化活性较小。光电化学表征结果显示：镍离子非均匀掺杂TiO₂薄膜的瞬时光电流信号较强，说明其光生载流子易于生成且分离效果较好；循环伏安曲线表明，光照时Ni非均匀掺杂的TiO₂薄膜改变了体系的氧化还原电位，说明了薄膜内建电场的建立。基于半导体的P-N结原理探讨了镍离子非均匀掺杂TiO₂薄膜的光催化活性机理。     

镧在TiO2薄膜中的非均匀掺杂对光催化性能的影响

采用溶胶-凝胶法制备了La^3＋非均匀掺杂的TiO2薄膜。通过对甲基橙的光催化降解实验来评价催化剂薄膜的催化活性，结果表明：La^3＋的掺杂方式对TiO2的催化活性有很大的影响，采用非均匀掺杂方式可以明显提高TiO2的催化活性，掺杂浓度以0．5％（原子分数）为最佳。紫外-可见漫反射光谱鼎示其吸收带边明显红移；电化学行为表明其光生空穴一电子对的形成能力和分离效率得到提高。通过比较太阳能光电池异质结的“窗口效应”理论，初步探讨了La^3＋非均匀掺杂对TiO2的光催化活性的影响机制。     

金属离子掺杂的TiO2薄膜的制备及其光催化降解甲苯的性能

 采用溶胶-凝胶法制备了负载于铝板上掺杂金属离子的TiO2薄膜光催化剂,并通过空气中甲苯光催化降解实验评价了其光催化活性. 结果表明,Pt和Fe的掺杂对TiO2薄膜的光催化活性起促进作用,甲苯降解率分别提高了17%和6%; Ag的掺杂引起催化剂失活; Mn的掺杂未对TiO2薄膜的光催化活性起明显促进作用. XRD结果表明,掺杂金属离子前后TiO2均为锐钛矿相; TEM观察到薄膜催化剂微观结构为球形颗粒,粒径分布均匀,平均粒径为19 nm; 紫外漫反射光谱表明,Pt-TiO2薄膜催化剂的反射率几乎为0,表明其对光的吸收能力很强,因而Pt掺杂的TiO2薄膜光催化降解甲苯的活性最高.     

氟掺杂纳米 TiO2 薄膜的低温制备及其光催化性能

 以氟化铵为氟源, 采用水热法制得氟掺杂 TiO2 (FTO) 溶胶, 并通过浸渍提拉法在低温下制备了 FTO 薄膜. 其中在 120 oC 下水热处理 10 h 所得的 TiO2 溶胶制备的薄膜均匀透明, 具有较高的光催化活性. 氟掺杂后的 TiO2 晶粒尺寸并未发生明显变化, 但薄膜的光催化活性显著升高. F/Ti 摩尔比为 0.01 时, FTO 薄膜的光催化活性最高, 比 TiO2 薄膜的活性升高了 23%. X 射线光电子能谱结果表明, 氟掺杂 TiO2 中的氟离子存在晶格取代掺杂和表面化学吸附两种形式. 这两种氟离子的共同作用是 FTO 薄膜光催化活性升高的主要原因.     

稀土离子掺杂对纳米TiO2光催化制氢活性的影响

采用溶胶-凝胶技术制备了纳米TiO2和一系列稀土离子掺杂的TiO2光催化剂,通过X射线衍射、透射电镜及N2吸附等技术对其进行了表征,考察了样品光催化分解水制氢的性能.结果表明,稀土离子掺杂有效抑制了TiO2粒子的生长,提高了粒子的分散性,增大了催化剂的比表面积,从而大幅度提高了其光催化分解水制氢的性能.其中,Gd3 掺杂的TiO2样品粒径最小,分散性最好,比表面积最大(是未掺杂TiO2的35倍).掺杂离子的电子构型对样品的光催化制氢活性有较大影响,具有全空电子构型的La3 和半充满电子构型的Gd3 掺杂的样品具有较高的光催化制氢活性(分别是未掺杂TiO2的3.69倍和3.72倍).     

TiO2/Mo-TiO2 的制备、表征和光催化活性

 采用溶胶-凝胶法制备了掺 Mo 的 TiO2 粉末, 再由其制得 TiO2/Mo-TiO2 复合物光催化剂. 使用 X 射线光电子能谱、X 射线衍射、透射电镜、N2 吸附-脱附、紫外-可见漫反射光谱和荧光光谱等手段对催化剂进行了表征. 在紫外光照射下, 以甲基橙溶液降解为探针反应, 研究了 Mo 掺杂量对样品光催化活性的影响. 结果表明, Mo-TiO2 催化剂的活性不如纯 TiO2, 这是因为 Mo 离子促进了光生载流子的复合; 而带有 n-n 异质结半导体结构的 TiO2/Mo-TiO2 复合催化剂具有比纯 TiO2 和 Mo-TiO2 催化剂更高的光催化活性. 当 Mo 掺杂摩尔分数为 2%, TiO2:Mo-TiO2 质量比为 10:1 时, 活性是纯 TiO2 的 1.57 倍.     

Effect of dopant concentration on photocatalytic activity of TiO2 film doped by Mn non-uniformly

The thin films of TiO₂ doped by Mn non-uniformly were prepared by sol-gel method under process control. In our preceding study, we investigated in detail, the effect of doping mode on the photocatalytic activity of TiO₂ films showing that Mn non-uniform doping can greatly enhance the activity. In this study we looked at the effect of doping concentration on the photocatalytic activity of the TiO₂ films. In this paper, the thin films were characterized by UV-vis spectrophotometer and electrochemical workstation. The activity of the photocatalyst was also evaluated by photocatalytic degradation rate of aqueous methyl orange under UV radiation. The results illustrate that the TiO₂ thin film doped by Mn non-uniformly at the optimal dopant concentration (0.7 at %) is of the highest activity, and on the contrary, the activity of those doped uniformly is decreased. As a comparison, in 80 min, the degradation rate of methyl orange is 62 %, 12 % and 34 % for Mn non-uniform doping film (0.7 at %), the uniform doping film (0.7 at %) and pure titanium dioxide film, respectively. We have seen that, for the doping and the pure TiO₂ films, the stronger signals of open circuit potential and transient photocurrent, the better photocatalytic activity. We also discusse the effect of dopant concentration on the photocatalytic activity of the TiO₂ films in terms of effective separation of the photon-generated carriers in the semiconductor.     

Co~(2+)掺杂的纳米TiO_2薄膜光催化特性及电化学阻抗谱研究

本文采用交流电沉积技术,在多孔氧化铝模板中合成出Co2+掺杂的纳米TiO2薄膜(Co2+/TiO2薄膜)。以次甲基蓝为降解物,研究了纳米Co2+/TiO2薄膜在可见光下的催化性能,考察了阳极偏压对光催化活性的影响。用电化学阻抗谱(EIS)研究了纳米Co2+/TiO2薄膜在次甲基蓝溶液中的电化学行为,给出了相应的等效电路和半导体能带结构参数-空间电荷层宽度。研究表明,适量Co2+掺杂可以提高TiO2薄膜的光催化活性。在Co2+/TiO2膜电极上施加一定阳极偏压,使空间电荷层宽度增加,因此能有效实现光生电子-空穴分离,进一步提高次甲基蓝的光催化降解效率。     

退火气氛对掺银TiO2薄膜结构和光催化性能的影响

本文采用sol-gel法制备了掺银的TiO2/glass纳米光催化薄膜,并分别在空气和真空条件下对薄膜进行退火处理, 结构和光催化性能的测试结果表明, 退火气氛对薄膜的结构和薄膜对染料溶液的光催化降解效率都有影响。经真空退火处理的TiO2及Ag-TiO2薄膜较空气中退火处理的同样薄膜的光催化性能都低, 但适量掺银的Ag-TiO2薄膜的光催化活性较TiO2有不同程度的增强。     

Fabrication and photocatalytic characterizations of ordered nanoporous X-doped (X = N, C, S, Ru, Te, and Si) TiO2/Al2O3 films on ITO/glass

Transparent, ordered nanoporous TiO2/Al2O3 composite films doped with metal elements (Ru, Si, and Te) and nonmetal elements (N, C, and S) were fabricated by successive anodization and sol-gel process directly on glass substrates covered with a tin-doped indium oxide (ITO) film. The doping of ruthenium, nitrogen, carbon, and sulfur in TiO2 exhibited an enhanced effect on the absorbance, while the doping of silicon and tellurium showed little effect. Particularly, the N- and Ru-doped TiO2/Al2O3 films on ITO/glass developed an enhanced absorption red shift of 580 nm (-N) and 500 nm (-Ru). The nanoporous TiO2/Al2O3 composite film exhibited the highest photocatalytic activity in decomposing acetaldehyde under ultraviolet-light irradiation, with a value of 13 times in initial reaction rate or 7.8 times in quantum yield higher than a commercially available TiO2 material, Degussa P25. The ultraviolet-light photocatalytic activities of nanoporous TiO2/Al2O3 films were enhanced by the doping of nitrogen, carbon, and sulfur but slightly weakened by the doping of ruthenium, silicon, and tellurium. Particularly, the nanoporous N-doped TiO2/Al2O3 films exhibited effective photocatalytic activity on ultraviolet light decomposition of a highly toxic dioxin, HpCDD, and gave the highest decomposition rate of approximately 95% (via 7 h of irradiation) for the specimen with a dopant content of 1.7 wt % nitrogen.     

Comparison of optical and structural properties of nanostructure TiO2 thin film doped by Sn and Nb

The thin films of TiO₂ doped by Sn or Nb were prepared by sol–gel method under process control. The effects of Sn and Nb doping on the structural, optical and photo-catalytic properties of applied thin films have been studied by X-ray diffraction (XRD) high resolution transmission electron microscopy and UV–Vis absorption spectroscopy. Surface chemical state of thin films was examined by atomic X-ray photoelectron spectroscopy. XRD results suggest that adding impurities has a great effect on the crystallinity and particle size of TiO₂. Titania rutile phase formation in thin film was promoted by Sn⁴⁺ addition but was inhibited by Nb⁵⁺ doping. The activity of the photocatalyst was evaluated by photocatalytic degradation kinetics of aqueous methylene blue under UV and Visible radiation. The results show that the photocatalytic activity of the Sn-doped TiO₂ thin film have a larger degradation efficiency than Nb-doped TiO₂ under visible light, but under UV light photocatalytic activity of the Nb-doped TiO₂ thin film is better.     

Preparation and Characterization of Bismuth Doped TiO2 Thin Films

A series of Bismuth-doped titanium oxide (Bi-doped TiO₂) thin films on glass substrates have been prepared by sol-gel dip coating process. The prepared catalysts were characterized by XRD and XPS. The photocatlytic activity of the thin film catalysts was evaluated through the photodegradation of aqueous methyl orange under UV illumination. The experiments demonstrated that the Bi-doped TiO₂ prepared was anatase phase. The doped bismuth was in the 3⁺ oxidation state. The presence of Bi significantly enhanced the photocatalytic activity of TiO₂ films. At calcination temperature of 500°C, with doping concentration of 2 wt %, Bi-doped TiO₂ thin film showed the highest photocatalyic activity.