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。     

葵二酸对纳米ZnO的有机表面修饰研究

利用葵二酸对纳米ZnO进行有机表面修饰。采用红外光谱(IR)、热分析(TG-DTA)、X射线光电子能谱(XPS)、透射电镜(TEM)、润湿性实验、分散性实验等对表面改性前后的纳米ZnO进行表征。红外光谱、TEM及XPS表明，在纳米ZnO表面包覆有葵二酸的有机层。热分析显示，包覆量约为14.5%。润湿性及分散性实验表明，经葵二酸改性的纳米ZnO的表面性质由亲水变为疏水。     

纳米TiO2表面接枝聚苯乙烯及其抗紫外老化研究

利用偶联剂γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)对纳米TiO₂进行表面预处理, 在此基础上通过分散聚合工艺制备聚苯乙烯(PSt)接枝包覆纳米TiO₂. 运用红外光谱、热重分析及透射电镜对处理前后纳米TiO₂进行了表征, 并通过紫外人工加速老化试验比较了表面处理前后纳米TiO₂对聚丙烯/聚苯乙烯(PP/PSt)体系的抗紫外老化性能. 结果显示: KH570与纳米TiO₂表面羟基进行了缩合, PSt在粒子表面实现了接枝聚合, 接枝率约为60% (w); PSt接枝包覆纳米TiO₂呈均匀的微球形, 纳米TiO₂被包覆于微球内部; PSt接枝包覆后纳米TiO₂在PP/PSt中的分散效果较改性前有显著的改进, 其抗紫外老化性能明显优于改性前体系.     

纸张涂料用纳米CaCO3表面改性的研究

利用铝锆偶联剂对纳米CaCO₃进行表面改性。采用红外光谱(IR)、X射线衍射分析(XRD)、热分析(TG-DTG)对改性前后的纳米CaCO₃进行了表征。通过透射电镜(TEM)、粒度分析、吸油值、比表面积及静滴接触角等实验对纳米CaCO₃的表面改性效果进行评价。红外光谱分析表明，偶联剂以化学键合的方式在纳米CaCO₃的表面形成化学吸附。TEM及粒度分析结果显示，未改性纳米CaCO₃存在严重的团聚现象，而改性后纳米CaCO₃的分散性有很大改善。经表面改性，水滴在纳米CaCO₃粉体压片表面静滴接触角变大，改性纳米CaCO₃同时具有亲水性和亲油性，能够较好地分散在水和有机相中。将改性前后的纳米CaCO₃分别加入到纸张涂料体系中，制得纳米CaCO₃复合纸张涂料。涂料流变实验表明，经铝锆偶联剂表面改性的纳米CaCO₃制得的复合纸张涂料具有较高的动态弹性模量和粘性模量。     

有机改性TiO2光催化剂的制备及可见光催化性能

以染料黄叱精(Chrysoidine G)和TiO₂ (Degussa P25)为原料, 利用甲苯二异氰酸酯为桥连体, 成功合成了一种有机改性的TiO₂光催化剂. 采用XRD, TEM, FT-IR, UV-Vis对所得催化剂进行了表征, 以亚甲基蓝降解为探针反应, 考察其可见光催化性能. 结果表明: 甲苯二异氰酸酯在黄叱精和TiO₂之间形成了稳定的化学键, 从而实现了对TiO₂的表面有机改性; 改性后的TiO₂在可见光区(400～550 nm)有明显的吸收; 与未改性TiO₂相比, 有机改性的TiO₂催化剂在可见光照射下表现出了很好的光催化性能.     

表面修饰的TiO2太阳能电池界面特性研究

用水热法制备了具有典型锐钛矿晶型的TiO₂纳米材料,采用Cr(NO₃)₃对TiO₂薄膜电极进行修饰改性。用X射线衍射(XRD)、扫描电子显微镜(SEM)和光电子能谱(XPS)测试电极的物相及表面结构,结果显示TiO₂薄膜表面包覆一层粒径较大的氧化铬颗粒,整个电极仍保持均匀的多孔结构。电流-电压(Ⅰ-Ⅴ)曲线测试结果显示,改性后最佳电极的短路电流和光电转换效率分别比改性前提高了31.1%和40.4%。用电化学阻抗谱(EIS)测试电池的界面特性,从测试结果可以看出,相同偏压下,改性后电池的TiO₂/染料/电解质界面电阻更大,说明氧化铬包覆层在一定程度上抑制了界面的电子复合,改善了电池的光电输出特性。     

氟改性纳米TiO2的制备及其光催化降解甲基橙机理

采用简易的沉淀-氟化-回流晶化法在低温下制备了氟改性纳米TiO₂ (F-TiO₂), 并通过透射电镜(TEM), X射线衍射(XRD), 傅里叶变换红外(FTIR)光谱, X射线光电子能谱(XPS)和漫反射光谱(DRS)等表征手段研究了粉末的形貌、晶型、元素形态和光吸收性质. 结果表明: 实验制得的F-TiO₂为椭圆形纳米颗粒, 粒径为5-8 nm; 氟离子能够有效抑制板钛矿相TiO₂的生成, 并同时提高锐钛矿相TiO₂的晶化度; 修饰的氟主要分布在TiO₂表面, 以化学吸附态为主, 并伴有少量的间隙氟. 光催化降解甲基橙的实验表明, 氟离子改性的TiO₂同时具有较高的全谱和可见光催化活性. 通过碱洗和焙烧的对照实验分析可知, F-TiO₂在可见光下降解甲基橙的机理是源于一种由TiO₂表面吸附氟和间隙氟共同增强的染料敏化降解作用.     

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。     

铁、铈共掺杂纳米TiO2溶胶的制备及抗菌性能

采用微波辅助胶溶工艺,在常压条件下,制备了可用于室内杀菌的铁、铈共掺杂纳米TiO₂水溶胶,通过X-射线衍射(XRD)、等离子体发射光谱(ICP)、动态光散射(DLS)、透射电镜(TEM)和X射线光电子能谱(XPS)对产物结构进行了表征,并选用白色葡萄球菌、大肠杆菌和枯草芽孢杆菌为受试菌种,分别在无光照、自然光照条件下,采用菌落计数法对水溶胶抗菌性能进行了检测。结果表明,用微波辅助胶溶工艺制备的Fe/Ce共掺杂纳米TiO₂为锐钛矿型,其平均粒径为10 nm。Fe/Ce的掺杂改性能有效提高纳米TiO₂水溶胶的抗菌性能,尤其是在自然光照条件下,Fe/Ce共掺杂纳米TiO₂溶胶在6 h内对各测试菌种的杀菌率均为95%以上,表明Fe/Ce共掺杂纳米TiO₂水溶胶具有很高的广谱杀菌性。采用透射电镜(TEM)对杀菌过程中的大肠杆菌菌体形态进行观测,探讨了Fe/Ce共掺杂纳米TiO₂水溶胶的抗菌机理。     

Ce掺杂Bi2MoO6/TiO2纳米纤维异质结的制备及可见光催化性能

以静电纺丝技术制备的TiO₂纳米纤维为基质,通过溶剂热法制备了异质结型稀土Ce掺杂Bi₂MoO₆/TiO₂复合纳米纤维。利用X射线衍射（XRD）、扫描电子显微镜（SEM）、X射线光电子能谱（XPS）、透射电镜（TEM）、紫外-可见漫反射光谱（UV-Vis DRS）以及荧光光谱（PL）等分析测试手段对样品的物相、形貌和光学性能等进行表征。以罗丹明B为模拟有机污染物,研究了样品的可见光催化性能。结果表明：在稀土掺杂样品中,Ce离子进入Bi₂MoO₆晶格,部分取代Bi³⁺,导致晶胞膨胀,晶格畸变,形成缺陷;与TiO₂复合形成异质结,有利于光生电荷的产生、转移和有效分离,从而提高TiO₂纳米纤维的光催化活性。可见光照射180 min,罗丹明B的降解率达到95.1%。经5次循环光催化降解活性基本不变,样品具有良好的光催化稳定性。     

The Effect of SiO2 Addition on the Grain Size and Photocatalytic Activity of TiO2 Thin Films

The uniform transparent TiO₂/SiO₂ nanometer composite thin films were prepared via sol-gel method on the soda lime glass substrates, and were characterized by X-ray photoelectron spectroscopy (XPS), FTIR spectroscopy, UV-VIS spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and BET surface areas. It was found that the addition of SiO₂ to TiO₂ thin films could suppress the grain growth of TiO₂ crystal and increase the hydroxyl content of the surface of TiO₂ films. The photocatalytic activity of the as-prepared TiO₂/SiO₂ composite thin films increases for SiO₂ content of less than 5 mol%.     

TiO<Subscript>2</Subscript>-based nanopowders obtained from different Ti-alkoxides

Pure TiO₂ and S-doped TiO₂ sol–gel nanopowders were prepared by controlled hydrolysis-condensation of titanium alkoxides. The influence of different Ti-alkoxides (tetraethyl-, tetraisopropyl- and tetrabutyl-orthotitanate) used in obtaining TiO₂ porous materials in similar conditions (water/alkoxide ratio, solvent/alkoxide ratio, pH and temperature of reaction) has been investigated. The relationship between the synthesis conditions and the properties of titania nanosized powders, such as thermal stability, phase composition, crystallinity, morphology and size of particles, BET surface area and the influence of dopant was investigated. The nature of the alkyl group strongly influences the main characteristics of the obtained oxide powders, fact which is pointed out by thermal analysis, X-ray diffraction, TEM and BET surface area measurements.     

Preparation and Characterization of Nano-TiO2/poly (methyl methacrylate) Hybrid Latex by Reverse Microemulsion Method and In-Situ Polymerization

The organic nano-TiO₂ was synthesized in reverse (W/O) microemulsion, using tetrabutyl titanate (TBOT) as precursor and γ-methacryloxypropyl trimethoxy silane (KH-570) as modifier. After phase inversion from W/O microemulsion to oil-in-water (O/W) emulsion, nano-TiO₂/poly(methyl methacrylate) hybrid latex was prepared via in-situ polymerization based on the O/W emulsion containing organic nano-TiO₂. Fourier transform infrared spectroscopy (FTIR) indicated that KH-570 was successfully grafted onto the surface of TiO₂ particles. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) demonstrated that the average diameter of nano-TiO₂ was about 10 nm and the hybrid latex had obvious core-shell structure with particle size of 155 nm. The TBOT content and the mass ratio of KH-570 to TOBT have important effect on the polymerization stability and storage stability of the hybrid latex. When the TBOT content was 5% and the mass ratio of KH-570 to TOBT was 0.6, the coagulation rate (C_r) was 3.0% and the zeta potential reached 36.1 mV. The possible formation mechanism of the hybrid latex was also proposed.     

表面修饰二氧化锡纳米微晶的制备与表征

制备了硅烷偶联剂KH-570表面修饰的SnO2纳米微晶，通过FT-IR、XPS、TEM和TG-DTA对其结构和表面特性进行表征和研究. FT-IR和XPS分析结果确证了KH-570与SnO2表面是以化学键合或物理吸附方式相结合,粒子表面存在酯基等有机官能团的红外吸收特征；观测到KH-570中Si原子的Si2s和Si2p谱线. TEM分析表明，表面修饰反应增强了SnO2纳米微晶的疏水性和分散性.由XPS和TG的实测数据探讨了纳米粒子具有较低包覆量的可能原因.     

一种纳米TiO2粉体防团聚的新方法

开发了一种新的低成本防团聚方法——泡沫悬浮法。对泡沫悬浮法和共沸蒸馏法的防团聚效果进行了系统比较。结果表明，泡沫悬浮法可以有效抑制煅烧过程中纳米TiO₂晶粒的粗化和一次粒径的长大。泡沫悬浮法所得纳米TiO₂的粉体还具有团聚粒径小、粒度分布窄以及比表面积大的优点。通过FTIR、TG、DTA和松装密度实验对泡沫悬浮法的防团聚机理进行了研究，提出了纳米TiO₂防团聚模型。     

纳米氮化硅粉粒的表面改性研究

纳米氮化硅具有很高的化学稳定性、耐高温性能、良好的机械性能及优异的介电性能(高介电常数、高介电强度)犤9犦,在许多领域有着广泛的应用。作为一种重要的陶瓷材料,目前对它的表面改性大多是采用烧结助剂包覆氮化硅粉粒,提高烧结助剂在氮化硅浆料中的分散程度及浆料的流动性,     

New synthesis of excellent visible-light TiO2−xNx photocatalyst using a very simple method

An excellent visible-light-responsive (from 400 to 550 nm) TiO_2−xN_x photocatalyst was prepared by a simple wet method. Hydrazine was used as a new nitrogen resource in this paper. Self-made amorphous titanium dioxide precursor powders were dipped into hydrazine hydrate, and calcined at low temperature (110 °C) in the air. The TiO_2−xN_x was successfully synthesized, following by spontaneous combustion. The photocatalyst was characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM), UV-Vis diffuse reflectance spectrometer (DRS), and X-ray photoelectron spectroscopy (XPS). Analysis of XPS indicated that N atoms were incorporated into the lattice of the titania crystal during the combustion of hydrazine on the surface of TiO₂. Ethylene was selected as a target pollutant under visible-light excitation to evaluate the activity of this photocatalyst. The newly prepared TiO_2−xN_x photocatalyst with strong photocatalytic activity and high photochemical stability under visible-light irradiation was firstly demonstrated in the experiment.     

Visible-light responsive dye-modified TiO2 photocatalyst

A series of dye-modified TiO₂ photocatalysts were synthesized using dye Chrysoidine G (CG), tolylene-2,4-diisocyanate (TDI), and commercial TiO₂ (Degussa P25) as starting materials. TDI was used as a bridging molecule whose two -NCO groups reacted with Ti-OH of TiO₂ and -NH₂ groups of CG, respectively. As a result, special organic complexes were formed on the TiO₂ surface via stable π-conjugated chemical bonds between TiO₂ and dye molecules, confirmed by FT-IR, XPS, and UV-vis spectra. Due to the existence of π-conjugated surface organic complexes, the as-synthesized photocatalysts showed a great improvement in visible absorption (400-550 nm). Methylene blue, as a photodegradation target, was used to evaluate the photocatalytic performance, and the dye-modified TiO₂ exhibited much better activity under the visible light irradiation than bare TiO₂.     

Study of Surface Modification of Nanosize Si3N4 with Macromolecular Coupling Agent LMPB-g-GMA in Different Solvents

A new macromolecular coupling agent, low-molecular-weight polybutadiene liquid rubber (LMPB)-glycidyl methacrylate (GMA), was synthesized using solution polymerization initiated by benzoyl peroxide (BPO). The molecular structure was confirmed by FTIR and NMR. This macromolecular LMPB-GMA was used for surface modification of silicon nitride (Si₃N₄) nanopowder in n-heptane, chloroform, ethyl acetate, and DMF, respectively. LMPB-GMA and modified nano-Si₃N₄ were systematically investigated by FTIR, NMR, TGA, and TEM. The results showed that LMPB-GMA bonded and formed an organic coating layer onto the surface of nanosized Si₃N₄ particles. The polarity of the solvents plays an important role in this process. Strong or weak polar both affect the results. The dosage loading of LMPB-GMA is 12 wt% of nanosized Si₃N₄. Nanosized Si₃N₄ modified in ethyl acetate has better dispersibility and stability than that modified in n-heptane or DMF. TEM pictures also reveal that modified nano-Si₃N₄ possesses good dispersibility.