SBA-16薄膜内生长碳纳米管阵列及其Fe的填充

以表面活性剂F-127、导电玻璃(ITO)为基底制备了三维体心立方结构(Im3m)的介孔SBA-16膜.该膜的(111)晶面垂直于ITO基底.采用电化学沉积技术将少量Fe沉积进入SBA-16膜的孔底,沉积Fe后的SBA-16膜于700℃下乙炔裂解生长碳纳米管,在SBA-16膜(孔)内生长直径均匀、间距相等的开口碳纳米管阵列.采用二次电沉积法可以制备高度有序的填充Fe的碳纳米管阵列.TEM的研究结果表明填充进碳纳米管的Fe具有单晶结构.     

以SBA-16为模板电沉积生长多孔氧化铁纳米线阵列

采用电化学沉积法以Mn改性的三维体心立方结构的介孔SBA-16膜为模板制备Fe纳米线.沉积Fe后的SBA-16膜以2%HF溶解SiO₂骨架,样品于550℃焙烧4 h.SEM和TEM的研究结果显示,所制备的Fe₂O₃纳米线互相平行,孔径均匀.XRD、电子衍射及HRTEM研究表明Fe₂O₃纳米线具有(多孔)单晶结构.     

以SBA-16薄膜/ITO为基底电沉积生长“花状”CdS纳米晶体

在酸性条件下,以导电玻璃(ITO)为基底合成sBA.16分子筛膜.所制备的SBA-16薄膜孔径均匀,具有体心立方结构(属于Im3m空间群).在由CdCl2和Na2S2O3组成的电解液中,调节pH值为2～3.利用直流恒电位电沉积法,调节电位为-0.7 V,沉积时间为50 min,在SBA-16膜/ITO电极表面电沉积生长出"花状"CdS纳米晶体,利用SEM、TEM等技术研究了CdS纳米晶体形貌和结构,同时进行了荧光光谱测试.结果表明,电沉积合成的CdS生长在电极表面而不是生长在介孔孔道中.并能够产生荧光谱峰.     

SIFSIX-3-Ni膜的制备及氢气分离性质

利用(NH₄)₂SiF₆修饰大孔玻璃基底后, 在溶剂热条件下制备了SIFSIX-3-Ni膜, 并研究了温度和浓度对制备SIFSIX-3-Ni膜的影响. 能谱分析(XPS)结果表明大孔玻璃表面引入了氟元素. SIFSIX-3-Ni膜的粉末X射线衍射(PXRD)峰位置和模拟结果一致, 表明成功制备出SIFSIX-3-Ni膜. 从扫描电子显微镜(SEM)照片中观察到膜连续均匀, 厚度约为20 μm. 热重分析(TGA)结果表明, 活化前的膜没有客体分子. 单组分测试结果表明, 膜的H₂, CO₂和N₂渗透量分别为6.83×10 ^-6, 7.42×10 ^-7和8.89×10 ^-7 mol·m ^-2·s ^-1·Pa ^-1, H₂/CO₂和H₂/N₂的理想分离比分别为9.20和7.68. 在连续测试5 h后, H₂, CO₂和N₂渗透量基本保持不变, 表明SIFSIX-3-Ni膜具有很好的稳定性.     

C60/SBA-15介孔复合材料的合成及其荧光性质的研究

通过对介孔SBA-15孔壁氨基化(SBA-15-NH₂),然后与C₆₀反应形成化学键,成功地将C₆₀组装进入SBA-15孔道中,合成了C₆₀/SBA-15介孔复合材料.通过X射线衍射(XRD)、红外光谱(FTIR)、紫外-可见光谱(UV-V is)和差热-热重分析(TG-DTA)等方法对其进行了表征.同时,对复合材料的荧光性质进行了研究.结果发现,SBA-15-NH₂在575 nm处出现发射峰,C₆₀/SBA-15介孔复合材料在554 nm处出现发射峰,峰位蓝移21 nm.     

有机溶剂热生长技术制备硫族化合物及其光学特性的研究

以有机溶剂热生长技术(solvothermaltechnique)制备了半导体硫族化合物(CdS、ZnS、MoS₂)等纳米颗粒,采用XRD、TEM等技术对其结构进行表征.以ITO导电玻璃以及导电聚合物(PANI、PPY)膜为基底,将纳米颗粒涂布其上并以PL法研究其光学特性,实验结果表明:经修饰后,材料的荧光发射位置发生显著的变化.     

SBA-15负载钒氧化物催化剂上甲烷选择氧化反应

对SBA-15负载的钒、钼、钨氧化物催化的甲烷选择氧化反应性能进行了比较,发现VO_x/SBA-15催化剂优于MoOx/SBA-15和WOx/SBA-15催化剂.针对钒氧化物催化剂,考察了不同钒源、不同载体以及少量P元素的添加对催化性能的影响,结果表明以SBA-15为载体的催化剂的性能好于MCM-41和Cab-O-Sil为载体的催化剂;与V₂O₅,VO(C₂O₄)相比,NH₄VO₃是制备性能良好的VO_x/SBA-15的钒源;在VO_x/SBA-15中,添加少量P元素后,HCHO的选择性有一定程度的提高.XRD,N₂物理吸附、UN-Raman和H₂-TPR表征结果表明,负载量低于3 wt%时,钒组分可能主要以高分散的单核的VO_x物种存在,我们推测该物种对甲烷选择氧化制甲醛起关键作用.     

疏水双功能介孔固体酸的合成及其在乙酸乙酯酯化反应中的应用

通过水热合成法一步合成了具有不同疏水基团－CH₃ 、－(CH₃)₂ 和－(CH₃)₃的双功能介孔固体酸SBA-15-SO₃H－(CH₃)_x催化剂。通过X射线粉末衍射(XRD)、N₂吸脱附、元素分析等方法对催化剂进行了表征,并在乙酸乙酯酯化反应中进行催化性能评价。结果表明,随着疏水前驱体中甲基数的增加,样品的疏水性增强。SBA-15-SO₃H-(CH₃)_x催化剂的催化活性随着疏水性的增强而提高,而具有较强疏水性的材料SBA-15-SO₃H-(CH₃)₃在反应中具有较高的催化性能。以SBA-15-SO₃H-(CH₃)₃为催化剂,酯化反应的最优条件为：温度为120℃,乙酸与乙醇摩尔比为4∶1,催化剂质量分数为1 %,反应时间为1h。在此条件下,乙醇的转化率和乙酸乙酯的选择性分别为93%和100%。     

碱土金属Ben (n=1~3)对B12团簇结构的调控研究

基于第一性原理, 系统地研究了Be_n (n=1~3)对B₁₂团簇结构的调控. 结果表明: 团簇BeB₁₂全局极小结构为C_s对称性准平面结构, 而Be₂B₁₂和Be₃B₁₂最稳定的结构均为笼状结构, 对称性分别为C_s和C_2v. 随着Be_n (n=1~3)原子数的增加, 团簇B₁₂由准平面结构过渡到笼状结构, 且Be倾向内嵌在B₁₂笼状结构表面的B₇或B₈单元环中, 通过离子和共价作用形成稳定Be&B₇和Be&B₈单元, 从而稳定笼状结构. 自然键轨道(NBO)分析表明, 团簇C_s BeB₁₂, C_s Be₂B₁₂, C_2v Be₃B₁₂内部存在电子转移情况, Be原子2s轨道上失去电子, Be—B键主要以离子作用为主, 同时也存在共价作用. 成键分析显示C_s Be₂B₁₂和C_2v Be₃B₁₂的π键遵循球状芳香性2(n+1)² (n=1)电子计数规则, 表明该团簇具有球状芳香性. 预测了三个结构的红外和拉曼光谱, 为以后的合成实验和数据表征提供了理论基础.     

16-脱氢黄体酮用梨头霉的羟基化

用梨头霉(Absidia orchidis)加羟基于16-脱氢黄体酮(1)与用黑根霉(Rhizopus nigricans)转化的结果不同,即羟基不加入于C₁₁而加入于C₆、C₇、C₁₅或兼而有之,且⊿¹⁶-双键不被饱和.所得产物是2～4,化合物(3)是主要产物.2～4的结构经化学转化和光谱方法测定.     

Synthesis and characterization of structure optimized film doped with Rhodamine 6G

Amplified spontaneous emission (ASE) property of a red dye rhodamine 6 g (R6G) doped into a highly ordered mesoporous SBA-15 film and a planar waveguide poly (4-vinylphenol) (P4VP) film were studied and compared. Regular morphology and mesoporous structure have been evidenced from the photographs, TEM and Nitrogen adsorption–desorption characterizations. A narrower, higher peak was observed in emission spectra from the meso-structured SBA-15 film doping with R6G (R6G/SBA-15) compared with the photoluminescence (PL) spectrum that of R6G in C₂H₅OH (R6G/C₂H₅OH) solution, was abruptly narrowed down to a line-width of about 9.8 nm when pumping at an energy of 0.12 mJ pulse⁻¹, which indicates a favorable ASE property in R6G/SBA-15 film. Comparing the P4VP film spin-coating with R6G (R6G/P4VP), the R6G/SBA-15 film exhibited a much narrower and stronger emission spectrum when it is pumped by the 355 nm pulsed source at the same pumping energy, which means that the meso-structure of the SBA-15 film can optimize ASE property of the material. The threshold was easily obtained by R6G/SBA-15 film at 0.02 mJ pulse⁻¹, and it was lower than that of R6G/P4VP film. The optimized ASE property owes much to the effects of the better spatial confinement of the molecules in the ordered mesoporous structure of SBA-15 film.     

Controlled growth of mesostructured crystalline iron oxide nanowires and Fe-filled carbon nanotube arrays templated by mesoporous silica SBA-16 film

The three-dimensional (3D) accessible pore structures (Imm space groups) of continuous mesoporous silica SBA-16 thin films have been prepared by a dip-coating technique in nonaqueous media under acidic conditions on indium-tin oxide glass (ITO). The films are oriented with the (111) crystal plane perpendicular to the surface of the film. On one hand, deposition of iron metal into the mesopores of SBA-16 films was achieved by using an electrochemical method. The Fe2O3 nanowire arrays were synthesized. The crystalline structures of porous Fe2O3 nanowires and nanorods were studied via TEM, SEM, and XRD. On the other hand, a small amount of Fe was deposited into the pores of the SBA-16 thin film as a catalyst, and carbon nanotube arrays formed inside the pores of SBA-16 film were fabricated by catalytic decomposition of acetylene at 700 degrees C. The second-order template synthesis method for preparing the ordered array of carbon nanotubes filled with Fe has been used. The carbon nanotubes are very uniform in diameter and length and are aligned vertically with respect to the SBA-16 film.     

介孔载体负载Pt催化剂上α-酮酸酯的不对称氢化

以介孔材料SBA-15、经或未经Al2O3修饰的具有三维立方孔道结构的SiO2为载体,制备了负载型Pt催化剂,并用于催化α-酮酸酯底物2-氧代-4-苯基-丁酸乙酯(EOPB)和丙酮酸乙酯(Etpy)的不对称氢化反应中.结果表明,当SBA-15孔径由6.2,7.6和9.2nm依次增加时,EOPB不对称氢化的活性和手性选择...     

Temperature Dependence in the Synthesis of SBA-16-Type Mesoporous Silica with Pluronic F68 Block Copolymer

By adjusting the local effective surfactant packing parameter through synthesis temperature, highly ordered SBA-16-type mesoporous silica materials have been synthesized by templating with a nonionic triblock copolymer Pluronic F68 in strongly acidic conditions at temperature 30～40°C with the addition of K₂SO₄. The prepared SBA-16-type mesoporous silica materials having Im3m cubic mesostructure were proved by the well-defined x-ray diffraction patterns combined with transmission electron microscopy. Scanning electron microscopy indicated that a transformation from faced-sphere to faced-polyhedron shape morphologies could be induced with increasing of the synthesis temperature. The nitrogen adsorption–desorption analysis revealed that the mean pore size (5.50～6.13 nm) of the prepared materials increased with increasing synthesis temperature. However, when the synthesis temperature exceeded 46°C, only disordered mesoporous silca was obtained. Our synthesis strategies by adjusting the local effective surfactant packing parameter through synthesis condition, even in a narrow range, would be used not only to optimize the synthesis conditions of reported mesoporous silca, but also to fabricate new mesoporous silica materials with well-ordered channel and anticipated morphologies.     

Mesoporous SBA-15 materials modified with PW or W active species as catalysts for the epoxidation of olefins with H<Subscript>2</Subscript>O<Subscript>2</Subscript>

Five catalysts containing PW or W active species that anchored onto aminosilylated mesoporous silica SBA-15 by a post-grafting route were prepared and the resulting PW or W/APTES/SBA-15 hybrid materials were characterized by XRD, N₂ adsorption/desorption, surface area analysis, TEM, FT-IR, and ICP (inductively coupled plasma atomic emission spectroscopy). The names of these catalysts have been abbreviated as SBA-15m-a, SBA-15m-b, SBA-15m-c, SBA-15m-d, and SBA-15m-e according to the different active species. The PW or W active species were highly dispersed in the channels of the modified mesoporous materials. The interaction between PW or W species and amino groups grafted on the channel surface of SBA-15 led to the immobilization of PW or W species. Their catalytic activity in the epoxidation of cyclooctene with H₂O₂ as oxidant was investigated. Among them, SBA-15m-a showed the best performance, with 98.9% conversion and 98.4% selectivity. The catalyst could be reused for six times with a little decrease in activity.     

Adsorption and structural properties of channel-like and cage-like organosilicas

Channel-like and cage-like mesoporous silicas, SBA-15 (P6mm symmetry group) and SBA-16 (Im3m symmetry group), were modified by introducing single ureidopropyl surface groups, mixed ureidopropyl and mercaptopropyl surface groups, and single bis(propyl)disulfide bridging groups. These hexagonal and cubic organosilicas were prepared under acidic conditions via co-condensation of tetraethyl orthosilicate (TEOS) and proper organosilanes using poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) amphiphilic block copolymer templates, P123 (EO₂₀PO₇₀EO₂₀) and F127 (EO₁₀₆PO₇₀EO₁₀₆). The modified SBA-15 and SBA-16 materials were synthesized by varying the molar ratio of organosilane to TEOS in the initial synthesis gel. The removal of polymeric templates, P123 and F127, was performed with ethanol/hydrochloric acid solution. In the case of SBA-15 the P123 template was fully extracted, whereas this extraction process was less efficient for the removal of F127 template from the SBA-16-type organosilicas; in the latter case a small residue of F127 was retained. The adsorption and structural properties of the resulting materials were studied by nitrogen adsorption-desorption isotherms at −196^∘C (surface area, pore size distribution, pore volumes), powder X-Ray diffraction, CHNS elemental analysis and high-resolution thermogravimetry. The structural ordering, the BET specific surface area, pore volume and pore size decreased for both channel-like and cage-like mesoporous organosilicas with increasing concentration of incorporated organic groups.     

Non‐covalent Immobilization of Iron‐triazole (Fe(Htrz)3) Molecular Mediator in Mesoporous Silica Films for the Electrochemical Detection of Hydrogen Peroxide

Mesoporous silica thin films encapsulating a molecular iron‐triazole complex, Fe(Htrz)₃ (Htrz=1,2,4,‐1H‐triazole), have been generated by electrochemically assisted self‐assembly (EASA) on indium‐tin oxide (ITO) electrode. The obtained modified electrodes are characterized by well‐defined voltammetric signals corresponding to the Fe^II/III centers of the Fe(Htrz)₃ species immobilized into the films, indicating fast electron transfer processes and stable operational stability. This is due to the presence of a high density of redox probes in the material (1.6×10^?4 mol g^?1 Fe(Htrz)₃ in the mesoporous silica film) enabling efficient charge transport by electron hopping. The mesoporous films are uniformly deposited over the whole electrode surface and they are characterized by a thickness of 110 nm and a wormlike mesostructure directed by the template role played by Fe(Htrz)₃ species in the EASA process. These species are durably immobilized in the material (they are not removed by solvent extraction). The composite mesoporous material (denoted Fe(Htrz)₃@SiO₂) is then used for the electrocatalytic detection of hydrogen peroxide, which can be performed by amperometry at an applied potential of ?0.4 V versus Ag/AgCl and by flow injection analysis. The organic‐inorganic hybrid film electrode displays good sensitivity for H₂O₂ sensing over a dynamic range from 5 to 300 μM, with a detection limit estimated at 2 μM.     

Preparation and characterization of (SBA-15)-La2O3 host-guest composite materials

Lanthanum oxide was successfully incorporated into an SBA-15 mesoporous molecular sieve via the microwave-assisted synthesis method (MASM) for the first time, and was compared with liquid-phase grafting and thermal diffusion methods. A series of characterizations were used to characterize the prepared materials. The results showed that the preparation of (SBA-15)-La₂O₃ host-guest composite materials by MASM has the advantages of simpler operation, higher efficiency and more plentiful lanthanum oxide could be incorporated into SBA-15 compared with other methods. In the prepared host-guest (SBA-15)-La₂O₃ materials, the frameworks of the host molecular sieve were kept intact, their structures were still kept high ordered and the guest lanthanum oxide locates inside the pores of the SBA-15. The sizes of the prepared (SBA-15)-La₂O₃ samples were 340-357 nm. The prepared host-guest composite materials show the properties of luminescence, and the luminescent intensities are about 2 times of bulk La₂O₃.     

Hemoglobin adsorption into TiO2 phytate multi-layer films: particle size and conductivity effects

Hemoglobin (molecular weight 64.5 kDa, isoelectric point 7.4) in 0.1 M phosphate buffer solution at pH 5.5 readily adsorbs onto mesoporous TiO₂ phytate films, which have been formed in a layer-by-layer deposition process from TiO₂ nanoparticles (ca. 6–10 nm diameter) and phytic acid at tin-doped indium oxide (ITO) electrodes. Quartz crystal microbalance data, voltammetry, and SEM evidence are consistent with hemoglobin adsorption only into the outer TiO₂ phytate surface layer. The size of the tetrametric hemoglobin protein (ca. 6 nm diameter) appears to be too big for a homogeneous film to form.The modified ITO electrode immersed in 0.1 M phosphate buffer solution at pH 5.5 allows reversible electron transfer for hemoglobin to be observed with a midpoint potential of 0.01 vs. SCE. Characteristic TiO₂ phytate film thickness and pH effects are observed with both thicker films and lower proton activity causing ‘decoupling’ of the protein redox chemistry due to a reduced electrical conductivity of the TiO₂ phytate film connecting hemoglobin with the electrode. This is the first example of a bi-layer nanofilm structure where the underlying TiO₂ phytate film controls the electrochemical properties of the hemoglobin modified top-layer.     

Thermal stability of high surface area silicon carbide materials

The synthesis of mesoporous silicon carbide by chemical vapor infiltration of dimethyl dichlorosilane into mesoporous silica SBA-15 and subsequent dissolution of the silica matrix with HF was investigated. The influence of the synthesis parameters of the composite material (SiC/SBA-15) on the final product (mesoporous SiC) was determined. Depending on the preparation conditions, materials with specific surface areas from 410 to 830 m² g⁻¹ and pore sizes between 2 and 10 nm with high mesopore volume (0.31-0.96 cm³ g⁻¹) were prepared. Additionally, the thermal stability of mesoporous silicon carbide at 1573 K in an inert atmosphere (argon) was investigated, and compared to that of SBA-15 and ordered mesoporous carbon (CMK-1). Mesoporous SiC has a much higher thermal textural stability as compared to SBA-15, but a lower stability than ordered mesoporous carbon CMK-1.