CO2在纳米SiO2/TiO2悬浮体系中的光催化还原

用水热法合成了氧化硅改性的具有高比表面积、高催化活性的锐钛型二氧化钛, 并在其悬浮体系中将CO₂光催化还原合成甲醇. 采用XRD, TEM, 物理吸附, UV-Vis吸收光谱和FTIR等表征手段对催化剂结构特征进行了研究. 结果表明: 添加氧化硅后, 氧化硅和二氧化钛之间形成Si—O—Ti键, 抑制了TiO₂晶粒生长, 提高了锐钛型TiO₂的比表面积, 且随着含硅量的增加, SiO₂/TiO₂的UV吸收逐步蓝移, 禁带宽度增加. 还原反应结果表明: SiO₂/TiO₂具有光催化还原活性, 且随着含硅量的增加先增加后减小, 当SiO₂质量分数为3.5%时, SiO₂/TiO₂复合催化剂反应活性最强, 5 h内甲醇产量可达到21.0 mg/L, 并有少量甲醛生成.     

超声场中纳米TiO2表面包覆氧化硅的研究

在超声场中，通过硅酸钠水解生成的无定形氧化硅对金红石相纳米TiO₂进行表面包覆，利用红外光谱、X射线光电子能谱、X射线衍射和透射电镜对所得样品进行了表征，并对纳米TiO₂的光稳定性和分散性进行了评价。红外光谱和X射线光电子能谱表明，氧化硅以化学键合的方式沉积在纳米TiO₂的表面，在包覆层和纳米TiO₂颗粒之间的界面上形成了Ti-O-Si键。TEM照片、表面元素分析和光稳定性实验显示，氧化硅在纳米TiO₂表面形成了均匀的包覆层，超声场有助于提高包覆层的均匀性和致密性。氧化硅的表面包覆提高了纳米TiO₂在水中的分散性、紫外线屏蔽能力和可见光透过性。随着氧化硅含量的增加，纳米TiO₂的光稳定性逐渐提高，当m(SiO₂)∶m(TiO₂)>1∶5时，纳米TiO₂的光稳定性基本不变，而且在热处理过程中纳米TiO₂的晶粒生长得到有效抑制。     

CO2在纳米SiO2/TiO2悬浮体系中的光催化还原

用水热法合成了氧化硅改性的具有高比表面积、高催化活性的锐钛型二氧化钛, 并在其悬浮体系中将CO₂光催化还原合成甲醇. 采用XRD, TEM, 物理吸附, UV-Vis吸收光谱和FTIR等表征手段对催化剂结构特征进行了研究. 结果表明: 添加氧化硅后, 氧化硅和二氧化钛之间形成Si—O—Ti键, 抑制了TiO₂晶粒生长, 提高了锐钛型TiO₂的比表面积, 且随着含硅量的增加, SiO₂/TiO₂的UV吸收逐步蓝移, 禁带宽度增加. 还原反应结果表明: SiO₂/TiO₂具有光催化还原活性, 且随着含硅量的增加先增加后减小, 当SiO₂质量分数为3.5%时, SiO₂/TiO₂复合催化剂反应活性最强, 5 h内甲醇产量可达到21.0 mg/L, 并有少量甲醛生成.     

V2O5-TiO2复合半导体光催化材料结构及光响应性能研究

采用溶胶凝胶法制备了V₂O₅-TiO₂复合半导体材料，通过Raman、XRD及UV-Vis DRS等实验方法研究了V₂O₅与TiO₂复合对材料表面组成、晶体结构以及光响应性能的影响。结果表明：钒加入后优先与TiO₂作用形成较为稳定的金红石型TiVO₄晶相，其中V⁴⁺是促进TiO₂发生相变的关键；随着钒加入量的增加，V₂O₅由表面高分散状态逐渐聚集形成晶相，并释放部分Ti⁴⁺使之形成锐钛矿型TiO₂晶相，使得体相中金红石型TiO₂的含量有所下降；复合后形成的TiVO₄晶相显著提高了材料对可见光的吸收率，并使其吸光域红移至460 nm左右。     

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。     

纳米TiO2有机表面改性的研究

利用硅烷偶联剂(KH-550)对表面包覆氧化硅的金红石相纳米TiO₂进行了有机表面改性。采用红外光谱(IR)、X射线光电子能谱(XPS)、热分析(TG-DTA)、BET、透射电镜(TEM)、润湿性和分散性实验等对表面改性前后的纳米TiO₂进行了表征。红外光谱和X射线光电子能谱表明，KH-550以化学键合的方式结合在纳米TiO₂的表面，并形成了有机包覆层。经测量，纳米TiO₂表面的KH-550的质量分数约为2.0%。讨论了产生KH-550理论包覆量与实际包覆量差异的原因。TEM、TG和BET得出的结果显示，在纳米TiO₂有机表面改性过程中存在明显的团聚现象，改进分散纳米TiO₂的方法是提高有机改性效果的关键。润湿性实验和分散性实验表明，经KH-550表面改性的纳米TiO₂同时具有亲水性和亲油性。     

TiO2纳米纤维无纺布的制备及光催化性能研究

以聚乙烯吡咯烷酮(PVP)作为配位剂与钛酸正丁酯(Ti(C₄H₉O)₄)反应制得前驱体，再以乙醇为溶剂，CH3COOH作为催化剂，采用静电纺丝法制得PVP/TiO₂复合纳米纤维，经550 ℃、700 ℃和900 ℃焙烧后分别得到以锐钛矿型的TiO₂为主、以金红石型TiO₂为主和完全金红石晶型的TiO₂纳米纤维。对所制得的纳米纤维的结晶度、纯度和形貌，分别采用差热-热重分析(TG-DTA)、红外光谱(IR)、X射线粉末衍射(XRD)、扫描电镜(SEM)等进行了表征。光降解苯酚水溶液的实验结果表明，550 ℃下煅烧得到的以锐钛矿占主体的TiO₂纳米纤维，2 h使浓度为50 mg·L^-1苯酚水溶液的降解率超过85%，这充分说明这种TiO₂电纺纳米纤维具有良好的光催化性能。     

SO42-改性后的TiO2(锐钛和/或金红石)表面上MoO3的分散性质研究

采用红外(IR)、拉曼(Raman)、X-射线衍射(XRD)、程序升温还原(TPR)等方法考察了经硫酸根改性后的金红石(SR)与锐钛矿(SA)的混合比例变化时的负载型催化剂，MoO₃ / TiO₂(SR+SA)，的一些物理化学性质(如活性组分MoO₃的分散行为、表面酸碱性、氧化还原性)的变化规律。结果表明：对于MoO₃ / TiO₂(SR+SA)样品，低含量MoO₃表面分散时倾向于优先与混合载体中的改性金红石(SR)发生作用；TiO₂载体表面SO₄^2-的存在，使得载体表面产生了新的酸性位，导致样品中表面分散的钼物种主要以聚合八面体状态存在。     

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。     

等离子体修饰磁载TiO2光催化剂性能研究

以化学共沉法制备的CoFe₂O₄纳米粒子为磁核,采用TiCl₄水解包覆技术制备磁载二氧化钛纳米复合粒子CoFe₂O₄ /TiO_x(TCF),利用低温等离子体技术修饰TCF制备了CoFe₂O₄/TiO₂(PTCF)纳米复合光催化剂。运用VSM(振动样品磁强计)技术对样品磁性能进行研究,结果表明：等离子体修饰后的复合材料仍具有较高的饱和磁化强度,可在外加磁场作用下实现催化剂在水中的分离与回收;样品的XRD、TEM和UV-Vis分析测试结果表明：等离子体修饰后的复合材料有锐钛矿型TiO₂存在;TEM谱图显示磁核CoFe₂O₄的平均粒径约为20 nm,TCF复合粒子的粒径约为30~40 nm,TiO₂包覆层的厚度为10~20 nm。与纯TiO₂相比PTCF样品对光的吸收拓展到整个紫外-可见区,扩大了光谱响应范围;对甲基橙溶液降解的光催化活性评价研究表明：TCF复合粒子等离子体修饰后的PTCF纳米复合光催剂的光催化活性明显提高。     

Study on mechanism of photocatalytic performance of La-doped TiO2/Ti photoelectrodes by theoretical and experimental methods

TiO₂ photoelectrodes with various nanostructures have been successfully prepared by the anodization method. The morphology, microstructure and optical properties of as-prepared photoelectrodes were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet/visible light diffuse reflectance spectra (UV/vis/DRS), surface photovoltage spectroscopy (SPS) and photocurrent. The electronic structure and optical properties of La doped/undoped TiO₂ photoelectrodes with different crystal structures were calculated by the density function theory. The photocatalytic and photoelectrocatalytic activities of as-prepared photoelectrodes were evaluated. The results showed that the anodization potentials played a crucial role in the surface morphology and microstructure. Both results of theoretical calculations and experimental tests demonstrated that La-doped photoelectrodes were more sensitive to light than undoped one. The difference of photoelectrodes performance was ascribed to the crystal configuration, impurity energy levels and long-range orientation moving of photogenerated carriers.     

Structure of TiO2 in TiO2-SiO2 prepared by a complexing agent-assisted sol-gel procedure

Many types of TiO₂-SiO₂ (Ti:Si=50:50 mol%) were prepared by the sol-gel procedure with and without 2-methyl-2, 4-pentanediol (MPD) as an organic ligand. The effect of MPD on the gel structure and the properties of the TiO₂ crystals were studied by XRD and raman spectroscopy, and the effect of the sol standing time on the properties of the TiO₂ crystals were also studied by XRD spectroscopy. In the gels with MPD, anatase of TiO₂ appeared at approximately 580°C, and the crystal structures were similar despite the difference in the gel preparation procedure. The titania gels with MPD were presumed to be dispersed in the silica gel matrix without any Ti-O-Si bond. In the presence of MPD, the formation of titania gels is controlled and the specified TiO₂ crystal is produced.     

荧光素-纳米二氧化钛表面复合及光诱导电子转移

本文研究了中性条件下TiO2纳米粒子与双阴离子态荧光素F2-的结合能力,发现所形成的复合物与文献报道的强酸性条件下TiO2-质子化荧光素H3F+复合物相比,结构与性能均很不同,F2--TiO2复合物吸收光谱红移30 nm以上且发射荧光。用UV-vis吸收光谱测定了复合物的结合常数、用稳态和瞬态荧光光谱测定了复合物的荧光效率和寿命分别为0.14和1.08 ns,与相应自由态F2-的测定值0.92和4.68 ns相比,复合物荧光效率和寿命都有很大的降低,这是由于复合物内部光诱导电子转移所致,因这一电子转移是热力学上非常有利的过程,其自由能变化达1.1 eV。光致电子转移的速率常数为7.1×108s-1,是其它竞争过程的3倍以上,复合物内光诱导电子转移效率达77%。     

Catalytic Ketonization of Acetic Acid on Zn/Al Layered Double Hydroxides

The effects of CuO loading, reaction temperature, and surface gas velocity (U_g) on the photocatalytic reduction of NO have been determined in an annular flow type and a modified two-dimensional fluidized bed photoreactor. The optimum CuO loading was found to be 3.3 wt.% and NO degradation conversion in the modified two-dimensional fluidized bed photoreactor is more than 70% at 2.5 U_mf.     

Sol-gel electrochromic device

All solid state electrochromic devices have potential applications in architectural and automotive fields to regulate the transmission and reflection of radiant energy. We present the optical and electrochemical characteristics of two solid state windows having the configuration glass/ITO/TiO₂-CeO₂/TiO₂/TiO₂-CeO₂/ITO/glass and glass/ITO/WO₃/TiO₂/TiO₂-CeO₂/ITO/glass where the three internal layers have been prepared by sol gel methods. The preparation of the individual sols and some physical properties of the different sol gel coatings are reported.     

Crystal phase evolution of TiO2 nanoparticles with reaction time in acidic solutions studied via freeze-drying method

The crystal phase evolution of TiO₂ nanoparticles, during hydrolysis and condensation of titanium tetraisopropoxide, was quenched at various reaction times by a freeze-drying method, followed by various characterizations. Three types of solutions with different acid input times were studied: (1) addition in infinite time (no addition), (2) addition at 24 h after the hydrolysis/condensation reaction started, and (3) addition from the beginning of the reaction. The acid-free solution yielded amorphous TiO₂, which transformed to anatase very slowly. The acid input in 24 h resulted in a fast transformation of amorphous to a metastable anatase having a highly distorted atomic arrangement: thereby its transformation to a more stable phase, rutile, was suitable. The acid addition from the beginning of the reaction yielded the formation of a relatively stable anatase from the hydrolysis seed, thereby the subsequent transformation to rutile was sluggish.     

Catalytic oxidation of no to NO2 over Cr/TiO2 and Cu/TiO2 under oxidizing atmosphere

The catalytic activity of Cr/TiO₂ and Cu/TiO₂ for the oxidation of NO under an oxidizing atmosphere has been examined. Both catalysts had excellent ability for the oxidation of NO to NO₂ in the temperature range of 350–400°C.     

Ultradeep Hydrodesulfurization of Dibenzothiophene (DBT) Derivatives over Mo-Sulfide Catalysts Supported on TiO2-Coated Alumina Composite

The present paper reviews in detail the different studies now being conducted by our research team concerning the ultradeep hydrodesulfurization (HDS) of dibenzothiophene (DBT) derivatives over Mo/TiO₂ and Mo/TiO₂–Al₂O₃ catalysts. First, a detailed characterization of Mo/TiO₂ (P-25 Degussa, 50 m²/g) catalysts prepared by equilibrium adsorption technique shows that Mo- species are highly and uniformly dispersed on the surface of titania up to 6.6 wt% MoO₃ loading. Above this value, some aggregation of Mo occurs, leading to the formation of bulk MoO₃. Below 6.6 wt% MoO₃ loading, the Raman spectroscopy data of the calcined samples show that the supported Mo-species possess a highly distorted octahedral MoO₆ structure. TiO₂–Al₂O₃ composites were prepared by chemical vapor deposition (CVD) using TiCl₄ as a precursor. Using several characterization techniques, we demonstrated that the support composite presents a high dispersion of TiO₂ over -Al₂O₃ without forming precipitates up to ca. 11 wt% loading. Moreover, the textural properties of the composite support are comparable to those of alumina. Under the present sulfidation conditions (673 K, 5%H₂S/95%H₂), Mo-species supported on TiO₂ are better sulfided than on alumina, as demonstrated using XPS. This can be attributed to the relatively lower interaction between Mo-species and titania. The state of sulfide species supported on the composite support can be considered as a transition state between TiO₂ and Al₂O₃. However, at relatively higher TiO₂ loadings (ca. 11 wt%), Mo/TiO₂–Al₂O₃ catalysts exhibit sulfidability similar to that of Mo/TiO₂. The HDS tests conducted in both the laboratory and in industry show that sulfide catalysts supported on TiO₂–Al₂O₃ (ca. 11 wt% TiO₂) are more active than those supported on TiO₂ or Al₂O₃.     

球形TiO2-Al2O3的制备、结构和理化性能研究

将Ti(SO₄)₂溶于稀盐酸合成酸性钛溶胶，再将其与铝溶胶和六次甲基四胺溶液混合后采用油柱成型法制备了球形TiO₂-Al₂O₃复合氧化物。通过XRD、低温氮吸附-脱附与NH₃-TPD等手段对样品进行表征，结果表明600 ℃焙烧得到的球形TiO₂-Al₂O₃中TiO₂以无定型形式存在;随TiO₂含量的增加，球形TiO₂-Al₂O₃的比表面积、孔容和平均孔径呈增加趋势;TiO₂的引入没有对球形TiO₂-Al₂O₃的强酸和弱酸中心的强度产生影响，弱酸中心数量显著增加，强酸中心数量稍有增加;球形TiO₂-Al₂O₃的堆密度和压碎强度随TiO₂含量的增加而减小，颗粒直径基本保持不变。     

An ultra-low hydrolysis sol-gel route for titanosilicate xerogels and their characterization

In this work TiO₂-SiO₂ xerogels were prepared through an ultra low hydrolysis method using titanium and silicon alkoxide. The samples were heat treated to 500°C. The xerogels were characterized using TGA/DTA, FTIR, XRD and TEM. The samples showed the formation of Si–O–Ti bridges by its characteristic vibration within 925–960 cm⁻¹ range. Si–O–Si bond angles were calculated using the central force network model. The TiO₂ in all the samples crystallized on heat treatment to 500°C. The crystallite size calculated using the Scherer formula from the XRD was verified from the Transmission Electron Micrograph. Samples heat treated to 350°C remained amorphous and hence could be used as hosts for biomaterials and organic optical materials.