溶胶-凝胶法制备SiO2/SiO2-TiO2双层防雾增透膜

以本征机械性能良好的溶胶-凝胶酸催化SiO₂和TiO₂薄膜为基础, 设计并制备了具有高透过率和良好机械性能的λ/4-λ/4 SiO₂/SiO₂-TiO₂双层增透膜. 所得薄膜在中心波长处的峰值透过率达到99.9%, 与设计膜层的透过率曲线高度吻合. 经耐摩擦和黏附性测试后, 该双层增透膜峰值透过率基本保持不变, 硬度高达4H, 表明其具有良好的机械性能. 水表面接触角测试结果显示该双层增透膜具有超亲水性, 表现出良好的冷/热防雾效果.     

SiO2交联剂交联MMA聚合制备PMMA/SiO2纳米复合材料

用SiO2交联剂(SiO2HPA)交联甲基丙烯酸甲酯(MMA)自由基聚合制备PMMA SiO2纳米复合材料。采用两步法将可聚合乙烯基单体以化学键的形式键接到SiO2表面合成SiO2交联剂,首先利用过量的甲苯2,4二异氰酸酯(TDI)对SiO2纳米粒子表面进行化学修饰合成出表面带有高反应活性NCO基团的功能化SiO2粒子(SiO2TDI),SiO2TDI与丙烯酸羟丙酯(HPA)反应合成SiO2交联剂。系统研究了MMA单体与SiO2交联剂投料比及聚合时间对聚合反应的影响。此外,利用红外光谱(FT IR)、DSC、TGA、可见光光谱仪等实验手段对纳米复合材料进行了表征分析。结果表明,纳米SiO2粒子在复合材料中起着物理交联点和化学交联点作用,复合材料玻璃化转变温度(Tg)明显地高于其纯PMMA的玻璃化转变温度,随着纳米SiO2粒子含量的增加,复合材料玻璃化温度升高,而透明度明显降低。     

偶联剂原位改性SiO2提高PEO/LiClO4/SiO2电导率

偶联剂原位改性SiO2提高PEO/LiClO4/SiO2电导率;PEO;聚合物电解质;偶联剂;SiO2;电导率     

On synthesis of Fe2SiO4/SiO2 and Fe2O3/SiO2 composites through sol–gel and solid-state reactions

Major processing factors in forming Fe₂SiO₄/SiO₂ and Fe₂O₃/SiO₂ powders via sol–gel synthesis followed by solid-state reactions are investigated. The results clearly indicate that the chemical compositions of the precursors, the ratio of the precursors, the nature of the catalyst used, and the gas atmosphere during solid-state reactions can all affect the outcome of the reaction product(s). The formation of Fe₂SiO₄/SiO₂ is enhanced by using the precursor iron(III) acetylacetonate as the Fe source with the precursor ratio of iron(III) acetylacetonate to tetraethyl orthosilicate being 1:1 and the addition of formic acid. Otherwise, crystalline Fe and Fe₃C are formed in place of Fe₂SiO₄. By altering the gas atmosphere during solid-state reactions from argon to oxygen, the reaction products change from Fe₂SiO₄/SiO₂ to Fe₂O₃/SiO₂. All of the observed phenomena can be rationalized via the degree of mixing of the Fe–O and Si–O domains at the molecular level in the gel network during sol–gel reactions and the presence of a reducing or oxidizing atmosphere during the solid-state reaction.     

新型SiO2/SiO2核壳型固定相的制备与评价

采用层层自组装的方法,以微米多孔硅胶小球为核,将硅胶纳米粒子多层包覆,制备了核壳型SiO2/SiO2硅胶小球.透射电子显微镜表明这种硅胶小球具有明显的核壳结构,氮气吸附实验证明该硅胶小球是典型的介孔材料,具有良好的介孔结构和窄的孔径分布.将其作为基质制备碳十八键合核壳型SiO2/SiO2色谱固定相,该固定相的碳含量与未...     

SiO2溶胶稳定性的研究

The theory of the stability of SiO_2 colloid in different electrolyte (NaCl) concen-tration was studied. It was found that the stability of SiO_2 colloidal dispersion was lower with the increase of eletrolyte (NaCl) concentration and the logw-logc relation was straight line. The potential curves in the system were constructed. The stability of SiO_2 colloidal dispersion correspond with the DLVO theory.     

二氧化碳在Pd/SiO2和La-Pd/SiO2上的催化氢化反应

对CO₂在附载型Pd催化剂上的氢化反应的研究迄今报道不多^[1,2],且都在加压条件下进行,对常压下助催剂如何改善Pd的催化行为未见报道。本文探讨了Pd/SiO₂催化剂,未加与掺加助催剂La(NO₃)₃后,其Pd粒大小、CO₂的吸附性能及CO₂/H₂催化活性等方面都有显著差异。     

Ru/SiO2和Pt/SiO2上CO加氢反应的量化计算

分子轨道理论在催化中的应用愈来愈受到重视.对在金属原子簇上分子的吸附进行过不少半经验的量化计算,但对在担体催化剂上反应气体的吸附及所进行的反应用量子化学处理尚不多见.本文通过在Pt/SiO_2,Ru/SiO_2上CO的吸附、H和CO的共吸附以及中间生成物—CH_2,—CH_3,—CH_2—CH_3在催化剂表面健合的EHMO计算,结合现在流行的CO+H_2生成烷烃的机理,对Ru/SiO_2上生成CH_4的活性高于Pt/SiO_2,Pt/     

Fabrication of NiO coated SiO2 and SiO2 coated NiO for the removal of Pb2＋ ions

We have prepared silica,SiO2coated NiO and NiO coated SiO2by sol-gel method.The physicochemical properties of the desired materials were investigated by surface charge properties,scanning electron microscopy（SEM）,energy dispersive X-ray（EDX） spectroscopy,surface area measurements and X-ray diffraction（XRD） analyses.The point of zero charge（PZC） of the solid was determined by the salt addition method.In coated materials,two PZC values were noted representing the surface charge of their counterparts.The SEM image of SiO2coated NiO displays a uniform coating of silica on the surface of NiO whereas in case of NiO coated SiO2,a honeycomb like appearance was observed with highly porous structures.In the diffractograms of NiO,the characteristic peaks were suppressed in NiO coated silica however,no diffraction peak could be seen in SiO2coated NiO.Batch adsorption technique was applied for the removal of Pb2＋ions from aqueous solution.The sorption trend for Pb2＋ions was observed in the order of NiO coated SiO2〉 SiO2coated NiO 〉 NiO 〉 SiO2.This trend confirms that the coated materials have more sorption capacities than their parent counterparts.     

Bi2SiO5半导体光催化剂

Bi基半导体光催化剂具备独特的电子能带结构、可调节与可拓展的光谱响应范围、低毒及组成元素供给丰富等优点,使其成为高效、可实用型光催化剂的重要候选者。而Bi基非金属氧酸盐作为新型半导体光催化剂,其非金属氧酸根的表面修饰作用及高结晶性使其呈现出更加独特的光催化活性。本文简要介绍了Bi基半导体光催化剂的结构特性及近几年的研究进展,重点综述了Bi基非金属氧酸盐的一员--Bi₂SiO₅及其制备、异质结的构建和电子能带结构的研究进展,并对其今后的研究与应用方向作了进一步的展望。