SnO2TiO2 复合半导体纳米薄膜的研究进展

本文概述了SnO₂TiO₂ 复合半导体纳米薄膜的发展历史和研究现状,对比分析了“混合”、“核壳”和“叠层”3 种复合薄膜的结构和性能特点,着重论述了叠层结构的SnO₂ /TiO₂复合薄膜的光电化学和光催化特性。结合作者的研究工作,探讨了SnO₂ /TiO₂双层复合薄膜上下层厚度对其光催化活性的影响,指出复合薄膜光催化活性的提高可归因于电子从TiO₂ 向SnO₂ 的迁移。最后对SnO₂ /TiO₂复合薄膜的局限性和发展潜势做一简要分析,强调了该复合薄膜本身的应用特点。     

基于SnO2为修饰层的Au-Pt / SnO2 / Au复合电极研究

用真空镀膜法在Au电极上沉积SnO₂薄膜，在HAuCl₄和H₂PtCl₄的混合溶液中利用直接还原法，将Au-Pt双金属纳米颗粒组装在SnO₂ / Au电极上，得到Au-Pt / SnO₂ / Au复合电极。采用SEM、TEM、XPS及CV曲线测定对Au-Pt / SnO₂ / Au复合电极进行了表征。结果表明:复合电极上双金属纳米颗粒分布均匀，粒子粒径约为25 nm左右。SnO₂作为修饰层以配位键与双金属纳米粒子结合。Au-Pt / SnO₂ / Au复合电极具有良好对甲醇氧化的电化学性能。     

Bi2S3/CdSe共修饰TiO2纳米管膜的构建及其光电化学阴极保护效应

为获得良好光电化学性能的TiO₂半导体复合膜,采用Bi₂S₃和CdSe对TiO₂纳米管膜进行共修饰。以阳极氧化法在Ti表面先制备TiO₂纳米管膜,再通过恒电流电沉积和连续离子层吸附反应在纳米管表面依次沉积CdSe和Bi₂S₃,构建了具有级联能带结构的Bi₂S₃/CdSe共修饰的TiO₂纳米管复合膜。结果表明,Bi₂S₃/CdSe/TiO₂纳米管复合膜对可见光吸收显著增强,光电化学性能大幅度提高。白光照射下,复合膜的光电流密度为670μA·cm^-2,达到了纯TiO₂纳米管膜的17.6倍。Bi₂S₃/CdSe/TiO₂复合膜作为光阳极可使0.5 mol·L^-1 NaCl溶液中的4...     

一维Ga2O3/SnO2纳米纤维的制备及其气敏性能

通过静电纺丝法制备了一维Ga2O3/SnO2纳米纤维,采用X射线衍射(XRD)、扫描电镜(SEM)、紫外可见漫反射光谱(UV-Vis DRS)等方法对材料进行了表征,测试了不同Ga2O3质量分数(0、40%、50%、60%、70%、100%)的Ga2O3/SnO2纳米纤维(650℃,5 h)对应元件对三甲胺、丙酮、乙醛、乙酸、氨气、乙醇、甲醛7种气体的气敏性能。结果表明:在室温(25℃)时,60%(w/w)Ga2O3-40%(w/w)SnO2纳米纤维对三甲胺气体具有较高的灵敏度和较短的响应/恢复时间。对1000μL·L^-1三甲胺的灵敏度达到51;检出限达到0.8μL·L^-1,其灵敏度为1.3。     

TiO2/SnO2复合光催化剂的耦合效应

采用改进的sol gel技术制备TiO2/SnO2耦合型半导体光催化剂,利用XRD、气相色谱 仪、粒度仪和表面光电压装置等研究了耦合型半导体光催化机理和光催化效率的影响因素, 并通过降解甲醛探讨其在空气污染治理中的作用.实验结果表明,添加20 ％(mol) SnO2的复 合半导体光催化剂,其光催化效率比纯TiO2高一倍以上.据实验结果和粒子紧密堆积原理,提 出强耦合效应和弱耦合效应的光催化反应模型,并用此模型较好地解释了TiO2/SnO2复合型半 导体光催化剂的光催化效率随SnO2含量变化规律.     

Preparation and magnetic properties of Fe-Nb co-doped SnO2

Fe³⁺-Nb⁵⁺ co-doped SnO₂ was prepared at 1200 °C by a simple chemical co-precipitation method. The Sn_1−2xFe_xNb_xO₂ solid solutions kept cassiterite structure in the range of 0<x?0.33, and their cell parameters decrease with increasing x. While x=0.40, a second phase with orthorhombic FeNbO₄ structure co-exists with the cassiterite phase, and the second phase becomes dominant while x?0.45. The magnetic measurements indicated that low doping ratio sample (x=0.03) exhibits paramagnetic behavior. A paramagnetic-to-antiferromagnetic phase transition was observed for the samples with higher doping ratio (x?0.15).     

Capped semiconductor colloids: Synthesis and photochemistry of CdS capped SnO2 nanocrystallites

Cds-capped SnO₂ (CdS@SnO₂) and SiO₂ (CdS@SiO₂) colloids of 50–80 ? in diameter have been prepared in aqueous medium. Significant quenching of CdS emission is observed in the CdS@SnO₂ system as the electrons are injected from the excited CdS shell into the SnO₂ core. Photoinduced charge separation in this system also results in transient bleaching in the 450 nm region. Picosecond laser flash photolysis studies of composite semiconductor nanoclusters that highlight the effect of the metal oxide core on the photophysical properties of the outer CdS shell are described. Contribution No. 3961 from the Notre Dame Radiation Laboratory, USA     

石墨相氮化碳/二氧化锡复合材料的制备及光催化性能

采用热聚合法和水热法相结合的方法制备了g-C_3N_4/SnO_2复合光催化剂。利用XRD、SEM、TEM、FT-IR和UV-Vis DRS等多种测试手段对所得样品的物相结构、微观形貌和吸光特性等进行了表征。结果表明,异质结构复合光催化剂的最大光吸收边位置相对纯相SnO_2发生了明显的红移,并且SnO_2颗粒均匀分布于g-C_3N_4表面,其中最优组分(50%-g-C_3N_4/SnO_2)光催化降解染料罗丹明B(RhB)的效率达到了纯相g-C_3N_4的3.78倍。     

Photoelectrochemical oxidation behavior of methanol on highly ordered TiO2 nanotube array electrodes

The highly ordered titanium dioxide nanotube array (HOTDNA) electrodes were prepared in hydrofluoric acid solution by electrochemical anodic oxidation technique on a pure titanium sheet. The HOTDNA electrodes were characterized by X-ray diffraction, SEM microscopy, and UV–vis spectra. It has shown high density, well ordered and uniform titanium dioxide nanotube array film covered on these electrodes and the TiO₂ structure depending on the heating condition, the anatase phase of TiO₂ appeared when heating to 500 °C. The photoelectrochemical characteristics of methanol in 0.5 M Na₂SO₄ on the HOTDNA electrodes were investigated. The cyclic voltammetry, photocurrent-time and open-circuit photopotential response of methanol on the HOTDNA electrode were represented and significant photogenerated current was observed upon illumination in the UV regions with the light of 253.7 nm central wavelength. The effect of variables such as light intensity, applied potential, and methanol concentration on the photoelectrochemical response was investigated. It was found that the photocurrent was greatly influenced by these factors.     

Parts per billion-level detection of benzene using SnO2/graphene nanocomposite composed of sub-6 nm SnO2 nanoparticles

In the present work, the SnO₂/graphene nanocomposite composed of 4–5 nm SnO₂ nanoparticles was synthesized using a simple wet chemical method for ppb-level detection of benzene. The formation mechanism of the nanocomposite was investigated systematically by means of simultaneous thermogravimetry analysis, X-ray diffraction, and X-ray photoelectron spectroscopy cooperated with transmission electron microscopy observations. The SnO₂/graphene nanocomposite showed a very attractive improved sensitivity to toxic volatile organic compounds, especially to benzene, compared to a traditional SnO₂. The responses of the nanocomposite to benzene were a little higher than those to ethanol and the detection limit reached 5 ppb to benzene which is, to our best knowledge, far lower than those reported previously.     

纳米SnO2的非水溶剂溶胶-凝胶法制备与表征

Nanometer SnO₂ powders were successfully prepared by non-hydrolytic sol-gel approach combined with heat treatments using tin tetrachloride as starting material and ethylene glycol as solvent. The reaction mechanism of the sol-gel process is proposed. Results indicate that the -OHCH₂CH₂OH- prevent Cl^- ion from accessing to tin Sn⁴⁺ due to steric effect, and hence increaseing the stability of the sol solution. Ethylene glycol functions not only as a complextion agent to form a polymer network but also as a “spacer” to modulate the distance between metal ions, preventing metal oxide particles from aggregation during desiccation of the sol. The effects of heat treatments on the evolution of structure and morphology of nanosized SnO₂ powders were studied. The powders with narrow size distribution around 15～20 nm could be obtained at 500 ℃ for 4 h.     

溶剂热法制备石墨烯/SnO2及其气敏性

采用溶剂热法制备了石墨烯/SnO_2(G/SnO_2)纳米材料,利用扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)等对G/SnO_2进行了表征,研究了石墨烯的量和溶剂热温度对该纳米材料气敏性能的影响。实验结果表明,石墨烯可以调节SnO_2晶体的生长:当石墨烯上清液的量为1 mL、热处理温度为160℃时,制备的G/SnO_2纳米材料在室温下对氨气具有较好的气敏选择性和较高的灵敏度;且当气体体积浓度为1 000μL·L~(-1)时,对NH3的灵敏度为266.4,检出限达到了0.01μL·L~(-1)。     

纳米SnO2@TiO2的制备及其光催化性能

以SnCl4和Ti(OBu)4为原料,采用活性层包覆法制备了SnO2@TiO2包覆型复合光催化剂,并用XPS、IR、XRD、TEM和BET等手段进行了表征,以二甲基二氯乙烯基磷酸酯（简称DDVP）稀释液为模拟废水,考察了SnO2@TiO2的光催化活性及降解液初始浓度对反应动力学的影响.结果表明：包覆粒子由锐钛矿型TiO2和金红石型SnO2组成;与纯SnO2、TiO2相比,SnO2@TiO2包覆粒子的光催化活性明显提高,DDVP稀释液被光催化降解属于零级反应,但反应表观速率常数与降解液初始浓度成正比.     

Ni2+掺杂Ti/SnO2-Sb2O5电极的制备及性能

采用溶胶凝胶法制备了Ni2+掺杂的Ti/SnO2-Sb2O5电极,并通过XRD、SEM、EDS、苯酚降解、加速寿命实验等技术手段,研究了Ni2+的掺杂对电极的结构、形貌、电催化性能及稳定性的影响。结果表明:Ni2+的掺入细化了SnO2晶粒,增大了电极的比表面积,改善了电极表面的龟裂程度,提高了电极的导电性能;相对于Ti/SnO2-Sb2O5电极Ni2+的掺入将苯酚完全降解的时间缩短为原来的40%,将电极的使用寿命提高为原来的4.8倍。     

LB技术制备SnO2-TiO2无机交替纳米薄膜

采用LB技术将SnO₂纳米粒子和TiO₂纳米粒子组装进花生酸的交替多层膜，通过热处理除去膜中的有机成分后，采用红外光谱、紫外可见光谱、X-光电子能谱、低角X-射线衍射、原子力显微镜以及扫描电子显微镜等手段对处理后的膜进行了形貌、组成和结构表征，表明制得的是SnO₂纳米粒子-TiO₂纳米粒子无机-无机交替的均匀的纳米薄膜。     

Ru掺杂SnO2半导体固溶体的电子结构研究

运用基于密度泛函理论的第一性原理方法,建立了SnO₂以及不同比例Ru掺杂的SnO₂超胞模型,在对其进行几何优化后计算了Sn_1-xRu_xO₂(x=0,1/16,1/12,1/8,1/6,1/4,1/2)半导体的电子结构,并讨论了其晶格参数、电荷密度、能带结构和态密度(包括分态密度)等性质。结果表明,掺杂后,晶格参数随掺杂量的增加线性减小,与实验值的偏差在4%以内;掺杂后,在费米能级处可以提供更多的填充电子,使得电子跃迁至导带更容易,固溶体的导电性增强。为Sn_1-xRu_xO₂固溶体电极材料的发展和应用提供了理论基础。     

溶胶-凝胶法可控制备氧化锡纳米晶包覆碳纳米管

采用溶胶-凝胶法制备了氧化锡纳米晶包覆的碳纳米管。自由Sn4+离子从稳定的Sn柠檬酸配合物中缓慢释放出来,迁移到碳纳米管上,并在碳纳米管上沉积形成了SnO2纳米晶,沉积过程完全为异相成核方式,在碳纳米管外并没有发现单独的SnO2纳米晶。这种溶胶-凝胶方法还可以用来制备无氯离子污染的、低团聚的纯SnO2纳米晶。     

柠檬酸溶解-热解法合成纳米晶SnO2粉体

The SnO₂ nanocrystaline powders were synthesized by citric acid dissolution-pyrolysis method. The medium products were analyzed by FTIR. The products were characterized by TG-DTA, XRD, TEM, SEM etc. The results showed that the Sn was coordinated with aconitase acid during the dissolution. The SnO₂ particles prepared by this method were with a mean size of 5～10 nm. The calcined products presented lacunose micro-arc structure, thus favoring the application as gas-sensitive materials.     

Ru掺杂SnO2半导体固溶体的电子结构研究

运用基于密度泛函理论的第一性原理方法,建立了SnO₂以及不同比例Ru掺杂的SnO₂超胞模型,在对其进行几何优化后计算了Sn_1-xRu_xO₂(x=0,1/16,1/12,1/8,1/6,1/4,1/2)半导体的电子结构,并讨论了其晶格参数、电荷密度、能带结构和态密度(包括分态密度)等性质。结果表明,掺杂后,晶格参数随掺杂量的增加线性减小,与实验值的偏差在4%以内;掺杂后,在费米能级处可以提供更多的填充电子,使得电子跃迁至导带更容易,固溶体的导电性增强。为Sn_1-xRu_xO₂固溶体电极材料的发展和应用提供了理论基础。     

Photoluminescence dependence on imposing bias for ZnGa2O4 and ZnGa2O4 activated with Mn or Cr n-type semiconductor electrodes

Photoluminescence (PL) dependence was investigated by imposing cathodic and anodic bias for ZnGa₂O₄, ZnGa₂O₄:Mn and ZnGa₂O₄:Cr n-type semiconductor electrodes. Under the cathodic bias PL intensity was weak at about 1/3 times compared with imposing no bias, while under the anodic bias the intensity was strong at about 2 times maximally by using the ZnGa₂O₄:Mn and ZnGa₂O₄:Cr electrodes although no change about the intensity was observed by using the ZnGa₂O₄ electrode. These results suggest that the emission attributed to recombination between electrons and holes is decreased by flow of cathodic current under the cathodic bias while the emission is increased to decrease at non-radiative transition rates under the anodic bias when the energy relaxation occurs.