不同合成过程对溶胶-凝胶法制备的ZnO/Ag纳米复合材料光催化性能的影响

以乙酸锌、硝酸银为前驱体,二乙醇胺作为稳定剂,利用溶胶-凝胶法分别采用一步法和两步法制备得到ZnO以及ZnO/Ag纳米复合粉体。所有ZnO/Ag复合物中Ag的含量均为3%(摩尔分数)。对所制备样品的结构和光学性质通过XRD、SEM、TEM、XPS、PL、UV-vis进行了表征,进而以甲基橙为模拟污染物进行了光催化测试。结果表明,不同方法制备得到的ZnO/Ag纳米粉体晶粒均匀,无明显团聚现象,面心立方结构的金属Ag吸附在纤锌矿结构的ZnO表面形成异质结。与纯ZnO相比,掺Ag极大地改善了样品在紫外光下的光催化活性。对不同合成工艺的比较表明,用溶胶-凝胶一步法制备的ZnO/Ag复合物的光催化活性最高,经紫外光照射70min可完全降解甲基橙。     

Synthesis and characterisation of nanosized TiO2-ZrO2 binary system prepared by an aqueous sol-gel process: Physical and sensing properties

Nanostructured TiO₂-ZrO₂ thin films and powders were prepared by a straightforward aqueous particulate sol-gel route. Titanium (IV) isopropoxide and zirconium (IV) acetate hydrate were used as precursors, and hydroxypropyl cellulose was used as a polymeric fugitive agent in order to increase the specific surface area. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy revealed that the powder were crystallised at the low temperature of 500 °C, containing anatase-TiO₂ and tetragonal-ZrO₂ phases. Furthermore, it was found that ZrO₂ retarded the anatase-to-rutile transformation up to 900 °C. The activation energies for crystallite growth of TiO₂ and ZrO₂ components in the binary system were calculated 10.16 and 3.12 kJ/mol, respectively. Transmission electron microscope (TEM) image showed that one of the smallest crystallite sizes was obtained for TiO₂-ZrO₂ binary mixed oxide, being 5 nm at 500 °C. Field emission scanning electron microscope (FESEM) analysis revealed that the deposited thin films had nanostructured morphology with the average grain size of 20 nm at 500 °C and 36 nm at 900 °C. Thin films produced under optimised conditions showed excellent microstructural properties for gas sensing applications. They exhibited a remarkable response towards low concentrations of CO and NO₂ gases at low operating temperature of 150 °C, resulted in an increase of thermal stability of sensing films as well as a decrease in the power consumption. Furthermore, calibration curves revealed that TiO₂-ZrO₂ sensor follows the power law, S = A[gas]^B (where S is sensor response, coefficients A and B are constants and [gas] is gas concentration) for the two types of gases, and it has excellent capability for the detection of low gas concentrations.     

溶胶-凝胶法在材料制备中的研究进展

介绍了溶胶凝胶理论和技术的历史背景以及研究现状,评述了近年来在电学、光学、热学以及生物-材料等领域中的应用和发展前景,指出了溶胶凝胶化学在材料制备存在的问题和发展趋势。-     

溶胶—凝胶法制备有机改性硅酸盐的研究进展

综述了有机改性硅酸盐的溶胶－凝胶合成路线，并简要介绍它们的结构、性能及应用     

纤维素-二氧化硅复合颗粒的制备与表征

探索了可用作色谱填料的纤维素-SiO2复合颗粒的制备方法,将纤维素和硅胶溶于NaOH／尿素体系中,得到纤维素-SiO2溶液,用溶胶一凝胶转相法制得复合颗粒．研究了乳化剂用量、搅拌转速、纤维素分子量以及纤维素和SiO2的投料比对所制备的复合颗粒粒径和形貌的影响,以扫描电镜、粒径分析等对复合颗粒进行了表征．发现粘度小的分散相和分子量小的纤维素适合制备粒径大的复合颗粒,反之亦然．当纤维素与SiOz的投料比大于3：1时,复合颗粒呈球形,小于3：1时,多数颗粒的形状为无定形;当乳化剂Span80的用量为10％,搅拌转速为600r／min时,复合颗粒的形状较规则．在不同的条件下,所制备颗粒的体积平均粒径为9～45μm,比表面积在110～4802／g之间．调节乳化剂用量、搅拌转速、纤维素分子量以及纤维素与SiO2的投料比,能制备出粒径适当、比表面积大的复合颗粒,这些颗粒具有介孔结构,且孔径分布较均匀,机械强度高,适合用作色谱分离填料．     

Cr沉积TiO_2复合薄膜的制备及其可见光催化性能

真空蒸镀法结合溶胶凝胶法成功制备Cr沉积TiO2三层复合薄膜.通过XRD、SEM、UV-vis等手段表征沉积Cr后的TiO2薄膜的结构、可见光吸收性能,以亚甲基蓝溶液为目标物评定其可见光光催化活性.结果表明:该法制备的Cr沉积TiO2复合薄膜,在723 K热处理后,蒸镀的金属层仍然为金属Cr,823 K时被氧化为Cr2O3.不同温度热处理后Cr沉积的TiO2复合薄膜在可见光区均表现出良好的光吸收性.而且随着热处理温度的升高,光吸收性能明显增强.降解实验表明,823 K热处理后的薄膜样品光催化性能最好.在可见光光照射2 h后,对亚甲基蓝溶液降解率接近40%.     

纳米TiO2的溶胶-凝胶法制备及其表征

以钛酸正丁酯（TNB）-去离子水-盐酸-乙酰丙酮（Acac）的乙醇溶液为反应体系,采用溶胶-凝胶法制备纳米TiO2溶胶颗粒。通过DLS、XRD和HRTEM等表征手段对TiO2颗粒的生成过程、其粒径和晶型的调控等方面进行研究。发现低温环境下TiO2的生成主要经历水解反应形成螯合物、缩合反应生成TiO2溶胶、TiO2溶胶颗粒融合这三个阶段。并且通过调节反应温度和催化剂浓度,可在无需高温锻烧的情况下,制得具有典型锐钛矿晶型的高分散性TiO2溶胶颗粒。     

溶胶-凝胶法制备HPMC／Si02杂化复合薄膜

采用溶胶-凝胶法（sol—gel）在聚乳酸（PLA）基膜上负载羟丙基甲基纤维素／二氧化硅（HPMC／SiO2）有机-无机杂化层,制备HPMC／Si02有杂化复合薄膜。表征和测试杂化复合薄膜的结构与性能。结果表明：当HPMC溶液体积分数为6％时,杂化复合薄膜的氧气阻隔性能比PLA薄膜的氧气阻隔性能提高了36倍,同时,杂化复合薄膜的拉伸强度优于PLA薄膜。     

Synthesis and magnetic properties of CuFe2O4 nanotube arrays

CuFe2O4 nanotube arrays with different outer diameters were synthesized in anodic aluminum oxide templates through sol-gel techniques followed by heating treatment processes. The morphology of the nanotube arrays was investigated by field emission scanning electron microscope and transmission electron microscopy, suggesting that the nanotube arrays are ordered and uniform. The X-ray diffraction results indicate that the crystal structure of the nanotube arrays is polycrystalline with a spinel-type structure. The measurements of magnetic properties indicate that CuFe2O4 nanotube arrays with outer diameter of 200 nm exhibit magnetic anisotropy with easy magnetization direction along the axis of nanotubes.