用溶致液晶聚合物模板合成具有催化活性的钯纳米微粒

贵金属的一些稳定簇与胶体（如钯），当它们的尺度小到纳米数量级时，就可在有机和无机化学反应中充当具备特殊性能的催化剂。但是，随着簇尺寸的减小，尽管每个原子的催化效率会有所提高，簇团聚的几率也将随之增大。为了防止团聚，制备金属纳米微粒时，通常需将稳定剂吸附到粒子表面，以防粒子团聚，且能控制粒子的大小。例如，要成功地制备具有催化活性的钯（ Pd）纳米微粒，需要有配合基、功能高聚物和表面活性剂。但使用稳定剂有一定不足，因为在纳米微粒的活性位置上若强烈地吸收稳定剂，可能会削弱其催化性能。稳定的金属纳米微粒还…     

反胶束法制备金属及磁性合金纳米颗粒

反胶束(Reverse Micelle)是水溶液同含有适量表面活性剂的有机溶液相混合后由自组装形成的一种油包水的溶液结构。我们在混合前的水溶液中加入金属离子，通过溶液混合使该金属离子被表面活性剂转移到反胶束中，然后往混合液中加入还原剂，从而使金属离子在反胶束内被还原，得到所需的金     

SiO_2包覆纳米TiO_2的初步探讨

为了改善纳米TiO2的分散性,利用表面包覆技术,在TiO2的表面形成致密的SiO2膜,以达到改性的目的。讨论了SiO2包覆纳米TiO2的作用、机理和包覆工艺条件,并对包覆后的TiO2通过透射电子显微镜、Z-3000Zeta电位与粒度分布仪以及红外光谱分别进行分析。实验结果表明,包膜后的TiO2表面状态发生了变化,TiO2在水溶液中的分散性能得到明显改善。由红外光谱得知,这种包覆不仅是物理包覆,也是一种化学键合,在TiO2的表面形成Ti—O—Si键。     

TiO2纳米材料对甲醛气体的气敏性能研究

采用溶胶-凝胶法合成了对甲醛气体（HCHO）敏感的纳米晶TiO2材料。利用X射线衍射（XRD）、X射线光电子能谱（XPS）等测试方法对TiO2纳米晶结构和表面态进行了表征。X射线衍射结果表明，随温度的增加，TiO2的晶型会由锐钛矿型逐渐转变为金红石型。制成了敏感元件，对甲醛气敏性能进行了测试。测试结果表明，500℃下焙烧2h所制得的锐钛矿型TiO2对甲醛气体有很好的敏感性能。     

表面活性剂在纳米材料合成中的应用

阐述了表面活性剂分散机制及在纳米材料制备中的分散作用,介绍了以表面活性剂为基础的各种纳米材料制备方法的机理:如以表面活性剂形成的各种有序聚集体为模板的模板法、用表面活性剂稳定形成的微乳液为介质的微乳法、水热法、溶胶-凝胶法等。重点总结了表面活性剂在不同方法制备纳米材料中的最新性、前沿性的研究成果,并展望了表面活性剂在该领域中的应用前景。     

多孔阳极铝上TiO2干凝胶内铕的光致发光

在多孔阳极铝表面用溶胶－凝胶法制备了含40％Eu2O3的TiO2膜层，并观察到铕在室温下的光致发光（峰值波长617nm)及光致发光强度与干凝胶含量的关系曲线。     

TiO2纳米材料对甲醛气体的气敏性能研究

采用溶胶-凝胶法合成了对甲醛气体(HCHO)敏感的纳米晶TiO2材料.利用X射线衍射(XRD)、X射线光电子能谱(XPS)等测试方法对TiO2纳米晶结构和表面态进行了表征.X射线衍射结果表明,随温度的增加,TiO2的晶型会由锐钛矿型逐渐转变为金红石型.制成了敏感元件,对甲醛气敏性能进行了测试.测试结果表明,500℃下焙烧2 h所制得的锐钛矿型TiO2对甲醛气体有很好的敏感性能.     

TiO_2纳米材料对甲醛气体的气敏性能研究

采用溶胶-凝胶法合成了对甲醛气体(HCHO)敏感的纳米晶TiO2材料。利用X射线衍射(XRD)、X射线光电子能谱(XPS)等测试方法对TiO2纳米晶结构和表面态进行了表征。X射线衍射结果表明,随温度的增加,TiO2的晶型会由锐钛矿型逐渐转变为金红石型。制成了敏感元件,对甲醛气敏性能进行了测试。测试结果表明,500℃下焙烧2h所制得的锐钛矿型TiO2对甲醛气体有很好的敏感性能。     

热压处理对TiO_2溶胶光电催化活性的影响

利用粒度分析仪、TEM、XRD等表征手段,研究了溶胶-凝胶法制得的纳米TiO2溶胶经热压处理后,纳米TiO2的晶粒尺寸和晶型对其薄膜的光电催化活性的影响。结果发现,经过200℃热压处理的纳米TiO2粒子粒径小,分布均匀,而且其薄膜的光电催化活性也高。     

膜厚对泡沫镍负载TiO2纳米薄膜附着度和光电响应的影响

采用溶胶-凝胶法与高温水热法相结合的复合方法制备了以泡沫镍为基底的不同膜层厚度的TiO2纳米薄膜光电极,并用场发射扫描电子显微镜（SEM）与电化学工作站对样品进行了表面形貌表征与光电性能测试。结果表明,膜层厚度为10层的TiO2纳米薄膜光电极的材料附着度最高,且具有最强的光电响应。研究结果为进一步优化泡沫镍负载TiO2纳米薄膜光电极的制备提供了有益参考。     

Copper‐Assisted Weak Polyelectrolyte Multilayer Formation on Microspheres and Subsequent Film Crosslinking

The formation of weak polyelectrolyte films on planar and spherical supports has recently evoked major interest, as such coatings allow novel material properties to be tunable by pH and salt adjustment of the polyelectrolyte deposition conditions. We report on the build up of multilayers of the weak polyelectrolytes poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH) on submicrometer‐sized polystyrene (PS) and silica colloid spheres (～ 500 nm) with the aid of copper ion templating. The copper ions complex to the carboxylate groups of PAA, facilitating the formation of PAA/PAH multilayers on the particles. Regular growth of the layers on the colloid spheres with each polyelectrolyte deposition step was confirmed by microelectrophoresis, single‐particle light scattering (SPLS), and transmission electron microscopy (TEM), with an average bilayer thickness of ～ 3 nm. The polyelectrolyte multilayer‐coated particles formed stable colloidal dispersions, with ζ‐potentials ranging from 30 mV (PAH outer layer) and –50 mV (PAA outer layer). Complementary quartz‐crystal microbalance and UV‐vis spectrophotometry studies on PAA/PAH multilayers formed on planar supports were performed to examine the film formation and the role of copper ion binding to the layers. PAA/PAH multilayers formed on colloid particles were also chemically crosslinked by using the activator 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide (EDC). The degree of film crosslinking could be readily controlled by varying the concentration of EDC employed. Following solvent decomposition of the template particles coated with crosslinked PAA/PAH multilayers, intact hollow polymer capsules were obtained. These capsules were found to be impenetrable to polystyrene.     

Surfactant‐Assisted Preparation of Novel Layered Silver Bromide‐Based Inorganic/Organic Nanosheets by Pulsed Laser Ablation in Aqueous Media

A novel layered AgBr‐based inorganic/organic nanocomposite was prepared by pulsed laser ablation (PLA) of Ag in aqueous media in the presence of cetyltrimethylammonium bromide (CTAB), and the formation mechanism of two‐dimensional nanosheet was discussed. TEM observations indicate that the obtained AgBr‐based inorganic/organic nanocomposite possesses a well‐defined two‐dimensional shape and that the size of the nanosheet can be changed with the surfactant concentration in the solution. X‐ray diffraction (XRD) pattern was composed of a series of peaks that could be indexed to (00l) reflections of a layered structure, and the basal spacing of 20.0 Å indicated that the surfactant was included between the AgBr interlayers in an interdigitated bilayer arrangement. In contrast, a layered inorganic/organic nanocomposite cannot be formed at a CTAB concentration lower than the critical micelle concentration (CMC). Based on our detailed investigation, we proposed the nanocomposite formation process, that is, that negatively charged inorganic AgBr was produced by a strong reaction between the ablated Ag species and the bromide ions, which are concurrently assembling with cationic surfactant molecules controlled by the charge‐matching mechanism.     

脉冲激光烧蚀法制备Ag纳米粒子胶体

为了研究激光参数对Ag纳米粒子胶体的影响,采用不同重复率和能量密度的脉冲激光对蒸馏水中的Ag靶烧蚀10 min来制备Ag纳米粒子胶体.通过透射电镜(TEM)和紫外-可见(UV-Vis)分光光度计分析了Ag纳米粒子胶体的大小、形貌和吸收光谱,同时由Image-ProPlus软件分析计算了粒子的平均粒径及其分布.结果表明,由重复率为10 Hz,能量密度为4.2 J/cm2的脉冲激光烧蚀10 min后制备的Ag胶体纳米粒子平均粒径最小(D=17.54 nm),粒径分布最窄(δ=36.86 nm),且形貌较均匀.从而证实了通过调节激光参数来控制纳米粒子尺寸和形貌的可行性.另外,在实验基础上,应用熔化生长"与爆炸"模型讨论了激光烧蚀工艺参数对Ag纳米粒子胶体的影响规律.     

In situ high-resolution transmission electron microscopy of photocatalytic reactions by excited electrons in ionic liquid

A transmission electron microscope (TEM) sample for observing photocatalysis in a liquid was prepared by using N,N,N-trimetyl-N-propylammonium-bis(trifluoromethanesulfonyl)imide. The ionic liquid (IL) was used as a reaction solvent. Tetrachloroauric acid was dissolved in the IL as gold ion species. Rutile particles were added in the solution as a photocatalyst. The low vapor pressure of the IL enables a diffusing system in high vacuum of TEM. Rutile particles were UV irradiated in that liquid phase. After 3 h UV irradiation, a gold particle of 8 nm diameter was grown on the TiO2 surface. Photonucleation of Au/TiO2 system was discussed from the high-resolution TEM images.     

TEM and HAADF-STEM study of a Au catalyst supported on a TiO2 nano-rod

Gold nanoparticles were deposited on TiO2 nano-rods by a deposition precipitation method. This Au/TiO2 nano-rods catalyst is active for CO oxidation even at temperatures less than 273K and is as active as the catalyst of Au supported on conventional TiO2 particles. Transmission electron microscopy (TEM) showed that the TiO2 nano-rods were composed of a single anatase crystal and had a pillar shape with an axis along the <111> direction surrounded by flat four [101] planes. High angle annular dark field scanning TEM (HAADF-STEM) also revealed that a Au platelet with a thickness of 0.5-1 nm was formed at the interface between TiO2 nano-rods. The Au platelet was not observed when conventional round particles of TiO2 were used as a support.     

Structural analyses by TEM of iridium deposited on TiO2 powder and rutile single crystal

It was found by transmission electron microscopy (TEM) that deposition precipitation of Ir onto TiO2 powder (Degussa P-25) produced Ir particles preferentially on the rutile phase. Iridium oxide particles supported on rutile TiO2 single crystal by deposition precipitation were also observed by TEM and scanning electron microscopy, and were found to exist as thin films of a few atoms. A structural change caused by hydrogen reduction was observed using high-resolution TEM and this was confirmed to be the iridium oxide film being reduced to metallic iridium particles.     

Inside Front Cover: Surfactant‐Assisted Preparation of Novel Layered Silver Bromide‐Based Inorganic/Organic Nanosheets by Pulsed Laser Ablation in Aqueous Media (Adv. Funct. Mater. 17/2007)

Novel layered AgBr‐based inorganic/organic nanosheets can be prepared by pulsed laser ablation of Ag in an aqueous solution of cetyltrimethylammonium bromide (CTAB), report Takeshi Sasaki, Naoto Koshizaki, and co‐workers on p. 3554. The green image shows the distribution of carbon in a nanosheet deposited on a holey carbon film. The nanosheet structure is composed of anionic bromine‐rich AgBr inorganic layers and cationic surfactant layers (CTA+) with an interdigitated bilayer arrangement. A novel layered AgBr‐based inorganic/organic nanocomposite was prepared by pulsed laser ablation (PLA) of Ag in aqueous media in the presence of cetyltrimethylammonium bromide (CTAB), and the formation mechanism of two‐dimensional nanosheet was discussed. TEM observations indicate that the obtained AgBr‐based inorganic/organic nanocomposite possesses a well‐defined two‐dimensional shape and that the size of the nanosheet can be changed with the surfactant concentration in the solution. X‐ray diffraction (XRD) pattern was composed of a series of peaks that could be indexed to (00l) reflections of a layered structure, and the basal spacing of 20.0 Å indicated that the surfactant was included between the AgBr interlayers in an interdigitated bilayer arrangement. In contrast, a layered inorganic/organic nanocomposite cannot be formed at a CTAB concentration lower than the critical micelle concentration (CMC). Based on our detailed investigation, we proposed the nanocomposite formation process, that is, that negatively charged inorganic AgBr was produced by a strong reaction between the ablated Ag species and the bromide ions, which are concurrently assembling with cationic surfactant molecules controlled by the charge‐matching mechanism.     

纳米TiO_2复合微粒的制备及应用

为了改善纳米半导体TiO2的分散性,制备了以微米级的PMMA塑料粒子为核心粒子的TiO2/PMMA复合微粒和以SiO2作为表面包覆的TiO2/SiO2复合粒子。通过对TiO2/PMMA进行紫外、SEM测试,发现由于TiO2粒子分散性的改善,复合微粒对紫外线的吸收能力为纳米TiO2与PMMA塑料粒子混合物的3～10倍。在对TiO2/SiO2进行TEM、XRD及比表面测试后,结果表明复合粒子是由4nm的SiO2膜和约12.6nm的TiO2核组成。     

水热法制备K0.5Bi0.5TiO3陶瓷粉体及其介电性能研究

采用水热法合成了K0.5Bi0.5TiO3(KBT)无铅压电陶瓷粉体.运用X线衍射(XRD)分析了KOH浓度及反应时间对产物物相的影响;利用扫描电镜(SEM)和透射电镜(TEM)观察研究了粉体的形貌.结果表明,增大碱浓度(4～12 mol/L)和延长反应时间都有利于KBT纳米粉体的合成.在220℃,KOH的起始浓度12 mol/L水热合成48 h的纯KBT相呈立方形结构,晶型规整,晶粒尺寸约为100nm.由水热法制备的粉体在1060℃烧结,获得介电损耗为0.05的致密压电陶瓷材料.