SnO2纳米颗粒制备及其对溶胶-凝胶Sb:SnO2薄膜性能的影响

以Sn(OEt)2为起始原料,采用水热晶化法合成了分散性良好的金红石结构的SnO2纳米颗粒.采用X射线衍射对其进行了表征,表明SnO2纳米颗粒的结晶性良好,颗粒尺寸小于10nm.将合成的SnO2纳米颗粒均匀分散到SbSnO2镀膜液中,经陈化后制成镀膜溶胶,以溶胶-凝胶浸渍镀膜工艺制备纳米颗粒掺杂SbSnO2薄膜.分别采用范德堡(Van Der Pauw)法、UV/VIS分光光度计和FTIR中红外分析仪测量并分析膜层的导电性能、光学性能及结构特征,研究了导电纳米颗粒添加对SbSnO2薄膜电性能、光学性能和结构的影响.     

复合电沉积制备SnO2/TiO2薄膜及其光电催化性能

为了寻求廉价、高效和稳定的光催化剂,用复合电沉积技术在紫铜片上制备了Sn/TiO2薄膜,经300℃热氧化使之形成SnO2/TiO2复合电极.利用SEM,XRD对薄膜进行了表征,以甲基橙为模型化合物,对复合电极的光催化和光电催化性能进行了测定.研究表明:该薄膜由0.3~1μm的颗粒构成,每个颗粒又由纳米晶粒形成;电极具有多孔结构,膜中的SnO2以两种不同的晶体结构存在;在薄膜质量相等的情况下,SnO2/TiO2薄膜的光催化活性是纯TiO2粒子膜的2.87倍;外加一定偏压下,其催化性能大幅度提高.     

溶胶-凝胶-冷冻法制备纳米TiO2及其表征

为解决纳米TiO2粉体易产生团聚的问题,采用溶胶-凝胶与冷冻干燥法制备纳米TiO2粉体.通过X射线衍射、扫描电子显微镜和紫外分光光度计对纳米TiO2粉体的物相组成、形貌和光催化活性进行了表征.实验结果表明:在400℃下所制得的TiO2纳米粉体的粒径约为6 nm,且粒度分布均匀,呈球形;所制得的TiO2纳米粉体在投加量为2 g/L时可使质量浓度为20 mg/L的甲基橙溶液在2.5 h内几乎全部降解.溶胶-凝胶与冷冻干燥法再结合阶段升温焙烧法可得到分散性好、粒径小和光催化活性好的粉体.     

TiO2纳米纤维的制备及其对染料的光催化降解性能

采用溶胶-凝胶与静电纺丝技术相结合的方法,将聚乙烯吡咯烷酮(PVP)和钛酸四正丁酯混合制得前驱体溶液,纺丝得PVP/TiO2复合纳米纤维,然后经500℃高温煅烧制备了TiO2纳米纤维光催化剂,通过其对阳离子艳红5GN、弱酸性黄GN、雷马素蓝RR等染料的降解研究了TiO2纳米纤维的光催化性能。利用扫描电子显微镜(SEM)观察了PVP/TiO2和TiO2纳米纤维的形貌结构;傅里叶变换红外光谱(FT-IR)证实了TiO2纳米纤维的形成;通过X射线衍射仪(XRD)对TiO2纳米纤维的晶型及晶粒大小进行了分析。结果表明制备出的TiO2纳米纤维形貌稳定,具有锐钛矿型TiO2结晶形态并对染料具有很好的光催化降解效果。     

C/SnO2/TiO2纳米复合物的制备及其电化学性能研究

通过碳化吸附在SnO2/TiO2电极上的葡萄糖制备出C/SnO2/TiO2纳米复合电极材料。采用晶体粉末衍射仪(XRD)、场发射扫描电镜(SEM)、X射线能谱分析(EDS)等手段对复合电极进行了表征。将复合电极作为锂离子电池负极材料,通过循环伏安和计时电位法研究了其电化学性能。结果表明,在大的电流密度200μA·cm-2下循环30次后,放电容量仍保持在120.1μAh·cm-2。相比SnO2/TiO2电极,C/SnO2/TiO2复合电极电化学性能显著提高,交流阻抗谱图也显示C/SnO2/TiO2纳米复合材料拥有更低的电荷转移电阻。     

Ag/TiO2纳米粒子的制备及其光催化降解苯酚的性能研究

采用溶胶-凝胶法制备了TiO₂和Ag/TiO₂纳米粒子,采用涂覆法制备了TiO₂和Ag/TiO₂纳米粒子光催化剂基板样品。使用XRD、SEM和拉曼光谱等手段,对TiO₂和Ag/TiO₂纳米粒子进行了晶格结构和表面形貌研究;通过UV-Vis,研究了TiO₂和Ag/TiO₂纳米粒子光催化剂基板样品在光催化反应器中对苯酚的光催化降解性能。结果表明,制备的TiO₂和Ag/TiO₂纳米粒子均为纯净的金红石相,二者表面形貌并没有明显区别,Ag单质粒子成功负载在TiO₂纳米材料上;Ag单质粒子的负载,明显增强了TiO₂纳米粒子对可见光的吸收,且Ag/TiO₂纳米粒子薄膜对苯酚的光催化降解性能明显优于TiO₂纳米粒子薄膜;在光催化降解1 h后,TiO₂纳米粒子薄膜仅催化降解了溶液中30%(质量分数)的苯酚,且光催化降解出现了饱和趋势,而Ag/TiO₂纳米粒子薄膜可催化降解溶液中50%(质量分数)的苯酚,且在光催化降解3 h后,仍未出现饱和趋势。     

TiO2/SnO2纳米晶膜的制备及其电学性能研究

采用丝网印刷的方式制备了TiO2纳米晶薄膜,然后在其上采用浸泡的方式制备了SnO2纳米晶薄膜,形成TiO2/SnO2膜结构的光阳极并应用于染料敏化太阳能电池。用SEM对样品进行了结构形貌分析,用电化学工作站研究表征了SnO2的浸泡溶液浓度和浸泡时间对光阳极的调制改性作用。SEM分析表明在TiO2纳米晶薄膜表面生长的SnO2纳米晶薄膜晶粒比TiO2更加细小,电学性能研究表明TiO2薄膜经过0.4 mol/L SnO2溶液浸泡处理50 min能对TiO2薄膜的结构及性能起到很好的改善作用,电池的光电转化效率提高了约7%。     

微波干燥法制备纳米TiO2光催化剂及其催化性能研究

以钛酸丁酯为前驱物,离子液体1-丁基-3-甲基咪唑四氟硼酸盐为模板剂,采用溶胶-凝胶法及微波干燥法制备了纳米TiO2光催化剂。通过XRD、SEM及BET对光催化剂进行结构表征,以甲基橙溶液为模拟污染物,太阳光为光源,评价了其光催化活性,考察了模板剂及微波干燥条件对纳米TiO2光催化剂活性的影响。结果表明,采用离子液体作为模板剂,微波干燥条件下制备的TiO2光催化剂活性明显高于普通溶胶-凝胶法制备的TiO2光催化剂,光照3h甲基橙溶液降解率可达到95%。     

纳米TiO2-ZnO复合材料的制备及其光催化性能

本文以TiO2纳米管阵列作为模板,利用溶胶-凝胶法制备ZnO@TiO2纳米复合材料,通过SEM等测试手段对其结构进行了表征,并进一步研究了该复合材料在紫外光下对亚甲基蓝溶液的光催化效率。发现ZnO@TiO2复合材料的光催化效率与模板孔深孔径有关,并且由于TiO2与ZnO间的电荷转移作用,使得纳米复合材料的光催化效率高于TiO2模板和ZnO@AAO光催化效率的线性加合。     

TiO2纳米丝的制备

通过阳极氧化制备了多孔性氧化铝膜,并以其为模板,采用溶胶凝胶法制得了TiO2纳米丝.     

One-pot synthesis of intestine-like SnO2/TiO2 hollow nanostructures

In the present study the intestine-like binary SnO₂/TiO₂ hollow nanostructures are one-pot synthesized in aqueous phase at room temperature via a colloid seeded deposition process in which the intestine-like hollow SnO₂ spheres and Ti(SO₄)₂ are used as colloid seeds and Ti-source, respectively. The novel core (SnO₂ hollow sphere)-shell (TiO₂) nanostructures possess a large surface area of 122 m²/g (calcined at 350 °C) and a high exposure of TiO₂ surface. The structural change of TiO₂ shell at different temperatures was investigated by means of X-ray diffraction and Raman spectroscopy. It was observed that the rutile TiO₂ could form even at room temperature due to the presence of SnO₂ core and the unique core-shell interaction.     

Effect of SnO2 on the photocatalytical properties of TiO2 films

TiO₂/SnO₂ thin films with different tin atomic percentages were successfully prepared on glass substrates by the spray pyrolysis method from an alcoholic solution of TiO[C₅H₇O₂]₂ with different concentrations of SnCl₄. The TiO₂/SnO₂ thin films prepared at 450 °C presented the anatase phase in polycrystalline configuration from %Sn = 0 in the starting solution up to %Sn = 20, at higher tin content the films present an amorphous configuration. The resulting thin films have a homogeneous surface structure with some porosity. The photocatalytical properties of the films were evaluated with the degradation of methylene blue. The products of the degradation reaction were identified by ¹H nuclear magnetic resonance and the film properties were studied by atomic force microscopy, scanning electron microscopy, UV–Vis spectroscopy, and X-ray diffraction.     

In-situ preparation of TiO2/SnO2 nanocrystalline sol for photocatalysis

A novel preparation method to synthesize TiO₂/SnO₂ nanocrystalline sol under mild conditions was presented. Ti(OC₄H₉)₄ used as a precursor was hydrolyzed in the rutile SnO₂ nanocrystalline sol, and in-situ formed TiO₂/SnO₂ nanocrystalline sol. The crystal structure, morphology and photocatalysis performance of samples were investigated. The results show that the additional rutile SnO₂ nano grains serve as heterogeneous crystal nucleus and exhibite the inducing effect on TiO₂ grains growth, thus leading to the changes in crystalline phase and particle morphology. In addition, the photoluminescence (PL) spectra analysis indicates that TiO₂/SnO₂ composite structure induces a better charge separation, and thus the photocatalytic activity of TiO₂/SnO₂ sol is increased significantly compared with TiO₂ sol.     

Preparation and super-hydrophilic properties of TiO2/SnO2 composite thin films

SnO₂-TiO₂ composite thin films were fabricated on soda-lime glass with sol-gel technology. By measuring the contact angle of the film surface and the degradation of methyl orange, we studied the influence of SnO₂ doping concentration, heat-treatment temperature and film thickness on the super-hydrophilicity and photocatalytic activity of the composite films. The results indicate that the doping of SnO₂ into TiO₂ can improve their hydrophilicity and photocatalytic activity, and the composite film with 1-5 mol% SnO₂ and heat-treated at 450°C is of super-hydrophilicity. The optimal SnO₂ concentration for the photocatalytic activity is 10 mol% and larger film thickness is helpful to reduce the contact angle of the composite films.     

TiO2 coated SnO2 nanosheet films for dye-sensitized solar cells

TiO₂-coated SnO₂ nanosheet (TiO₂-SnO₂ NS) films about 300 nm in thickness were fabricated on fluorine-doped tin oxide glass by a two-step process with facile solution-grown approach and subsequent hydrolysis of TiCl₄ aqueous solution. The as-prepared TiO₂-SnO₂ NSs were characterized by scanning electron microscopy and X-ray diffraction. The performances of the dye-sensitized solar cells (DSCs) with TiO₂-SnO₂ NSs were analyzed by current-voltage measurements and electrochemical impedance spectroscopy. Experimental results show that the introduction of TiO₂-SnO₂ NSs can provide an efficient electron transition channel along the SnO₂ nanosheets, increase the short current density, and finally improve the conversion efficiency for the DSCs from 4.52 to 5.71%.     

Epitaxial growth of SnO2 film on Sn-doped TiO2(110)

Using a simple vacuum deposition-and-annealing method, Sn-doped TiO₂ (110) single crystals were prepared. Compared with the case of a pure TiO₂ substrate, the lattice mismatch between SnO₂ and the Sn-doped TiO₂ was reduced to −2.85% for the a-axis from −3.25 to −2.85% and for the c-axis from −7.35 to −6.62%. Surface morphologies of deposited SnO₂ films were compared on the Sn-doped TiO₂ (110) and on the pure TiO₂ (110). Results showed that the use of Sn-doped TiO₂ (110) single crystal as a substrate was favorable for growing epitaxial SnO₂ (110) films.     

High pressure synthesis of orthorhombic SnO2

A dense form of SnO₂ with an orthorhombic structure has been synthesized at 158 kbar and 800 °C. The boundary separating the normal pressure phase (tetragonal SnO₂-I) from the high pressure phase (orthorhombic SnO₂-II) is represented by P(kbar) = 140.0 + 0.022 T(°C). The lattice parameters of the quenched high pressure phase (SnO₂-II) are : $\text{a}\text{= 4.714 ± 0.001}\text{A}\text{?}$, $\text{b}\text{= 5.727 ± 0.001}\text{A}\text{?}$ and $\text{c}\text{= 5.214 ± 0.001}\text{A}\text{?}$ with the cell volume $\text{V}\text{= 140.8 ± 0.1}\text{A}\text{?}{}^3$. The volume decrease for the transition is calculated to be 1.8 %.     

Microwave-assisted synthesis and investigation of SnO2 nanoparticles

Microwave technique was adopted for preparation of tin dioxide nanoparticles with particles size ranging from 10 to 11 nm within 10 min. The formation of monocrystalline SnO₂ nanoparticles was confirmed by the XRD (X-Ray Diffraction) and TEM (Transmission Electron Microscopy) as well as with SAED (Selected Area Electron Diffraction) analysis. The structure of the SnO₂ crystal was found to be Cassiterite type tetragonal structure. The FT-IR results further supported the formation of tin dioxide from tin hydroxyl group without any post annealing. The samples were further characterized by thermo gravimetric analysis (TGA), electrical resistance measurements and photoluminescence spectrum.     

Preparation and photocatalytic activity of WO3/TiO2 nanocomposite particles

A novel photocatalyst WO₃/TiO₂ nanocomposite was prepared through a hydrothermal method by using cetyltrimethylammonium bromide (CTAB) as surfactant. The obtained WO₃/TiO₂ was characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM) and diffused reflectance spectroscopy (DRS). Photocatalytic experiments indicate that the nanocomposites show much higher photoactivity than that of pure TiO₂ in the photodegradation reaction of Rhodamine B (RhB). The increased photoactivity of WO₃/TO₂ may be attributed to the improvement of the light absorption properties and the slow down of the recombination between the photoexcited electrons and holes during the photoreaction.     

Photocatalytic degradation of pendimethalin over Cu2O/SnO2/graphene and SnO2/graphene nanocomposite photocatalysts under visible light irradiation

The Cu₂O/SnO₂/graphene (CSG) and SnO₂/graphene (SG) nanocomposite photocatalysts were prepared by simple sol-gel growth method, and characterized by Fourier transform infrared spectra (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) measurements, respectively. The photocatalytic efficiency of catalysts were evaluated by degradation of pendimethalin under visible light irradiation (λ > 420 nm), which conformed that CSG and SG exhibited better photocatalytic activity than SnO₂ or graphene alone. An effort has been made to correlate the photoelectro-chemical behavior of these samples to the rate of photocatalytic degradation of pendimethalin.