基于AFM纳米氧化技术的金纳米粒子定点组装

二维纳米粒子矩阵列在纳米电子器件^[1,2]、表面增强喇曼活性基底^[3,4]、刻蚀掩模^[5]等领域具有广泛的应用前景。在这些纳米粒子阵列为内部,纳米粒子的排布是随机、无序的。这一缺点已经妨碍了纳米粒子阵列在上述领域中的进一步应用。基于此,人们开始关注纳米粒子的可控组装。传统的光刻技术^[6]、微接触印刷技术^[7]以及生物分子模板技术^[8]都被用来实现纳米粒子在固体表面上的可控组装,本实验室在纳米粒子的合成及可控组装方面也进行了研究^[7,9,11]。本文力图精确控制单个纳米粒子在基底表面上的组装位置。利用AFM纳米氧化技术。在硅表面构建了纳米级的化学图形化表面,通过不同的化学官能团,如甲基、氨基对金纳米粒子亲和性质的差异,实现了纳米粒子在固体表面的定点组装。     

二氧化硅纳米粒子表面修饰及其表征

采用溶胶-凝胶法合成粒径在50—150nm范围内的二氧化硅（SiO2）纳米粒子。用甲基丙烯酸-3-（三甲氧基硅基）丙酯（MPS）对SiO2纳米粒子表面进行修饰，使其表面接枝能参与自由基聚合反应的碳碳双键基团。用元素分析、FTIR、^13C CP／MASNMR和^29Si CP／MASNMR等手段对修饰过的SiO2纳米粒子进行表征，以确证MPS接枝在SiO2纳米粒子上。分析修饰过的SiO2纳米粒子的^29Si CP／MASNMR和FTIR谱图，还可初步推断MPS接枝在SiO2纳米粒子表面的机理：MPS首先发生水解缩合反应形成低聚物，然后通过氢键作用吸附到SiO2纳米粒子表面，最后MPS低聚物中未缩合的硅羟基与SiO2纳米粒子表面的硅羟基发生缩合反应。     

用PAANa掺杂的纳米CaCO_3的合成及其产品表征

在反应物经超声波预处理和聚丙烯酸钠PAANa分散剂的掺杂下运用化学沉淀方法制备出窄粒径纳米碳酸钙。将所获纳米粒子运用现代分析测试手段进行结构、晶形、组成等的表征。结果表明纳米级超细碳酸钙在红外区有蓝移40cm-1和峰形窄化现象纳米粒子的高表面能及CO32-存在的共轭体系CaO键的相互作用以及表面配位的不饱和性和晶体生长的人为终止是存在表面效应的主要原因。     

玻璃中银粒子对稀土离子发光影响的研究

在玻璃制备过程中加入硝酸银,然后通过高温退火得到包含银纳米粒子的Er^3＋掺杂锗酸盐玻璃和Eu^3＋掺杂硼酸盐玻璃样品。根据Mie—Drude理论拟合了这些玻璃样品中银纳米粒子等离子体振荡吸收谱,得到了退火时间与银粒子粒径的关系。用488nm Ar^＋激光器激发不同退火时间的这些玻璃样品,分别监测Er3^3＋的^4S3/2-^4I15/2和Eu^3＋的^5D0-^7F2的发射,发现包含银纳米粒子的玻璃样品较不包含银纳米粒子的玻璃样品,Er3^3＋和Eu^3＋的发射分别增强3．6和1.25倍。通过分析玻璃样品的吸收谱和发射谱,排出了表面等离子振荡引起稀土离子发射增强的可能性。对Er^3＋掺杂的玻璃样品进行Judd—Ofelt理论分析,发现随着退火时间增加J-O强度参数减小,Er^3＋的^4S3/2能级的辐射跃迁几率保持增加,表明引入银纳米粒子引起稀土离子周围晶体场发生变化是稀土离子发光增强的一个原因。     

Nafion聚离子修饰纳米Pt的合成及其影响因素

采用化学还原的方法成功地合成了Nafion聚离子修饰的纳米Pt颗粒，平均粒径为～4nm；由于表面缺电子的特性，纳米Pt粒子与Nafion高分子长链上的-SO3^-基团有较强的结合，使粒子随-SO3^的存在状态而分散，在水溶液中呈现与离子团簇相似的分散状态。FTIR显示Pt颗粒存在表面原子暴露在修饰离子之外，因此，这种粒子在具有功能结构的催化领域有着很好的应用前景；合成过程中反应速率随Nafion含量的降低、pH的增加而增大。     

Pt纳米粒子/Pd纳米线复合材料对乙醇的电催化氧化研究

采用恒电位法在多孔阳极氧化铝模板中电沉积Pd纳米线阵列,再运用循环伏安法在Pd纳米线阵列表面沉积Pt纳米粒子制备出复合纳米材料电极。运用循环伏安法和计时电流法研究了该复合纳米材料电极对乙醇的电催化性能的影响。结果表明,Pt纳米粒子/Pd纳米线复合电极相比于单独的Pd纳米线电极或Pt纳米粒子电极,对乙醇氧化有更高的电催化活性和很好的稳定性。     

表面修饰二氧化钛纳米粒子的结构表征及形成机理

利用溶胶 凝胶法在混合溶剂中制备了硬脂酸表面修饰TiO2纳米粒子,对所合成的纳米粒子通过FTIR、XPS、XRD和TEM对其结构进行表征.结果确证了表面有机修饰层的存在,并且是羧酸根与无机内核以双齿配位形式结合;无机纳米内核的结晶度很低,但是可以确定为锐钛矿成分,平均粒径约为6～8 nm.提出了表面修饰纳米粒子的形成机理,认为在体系中硬脂酸和水之间发生竞争反应,其过程类似于聚合 阻聚反应,最后给出了硬脂酸表面修饰TiO2纳米粒子的结构模型.     

纳米粒子表面蛋白构象的交联质谱原位蛋白质组表征

采用基于化学交联质谱(Chemical cross-linking mass spectrometry,CXMS)的蛋白质组学方法研究了四氧化三铁(Fe3O4)纳米粒子表面牛血清白蛋白(BSA)的构象变化,考察了纳米粒子的曲率半径和蛋白孵育浓度与Fe_3O_4纳米粒子表面BSA构象的关系。CXMS结合傅里叶变换衰减全反射红外光谱(Attenuated total reflectance Fourier transform infrared spectroscopy,ATR-FTIR)的蛋白质二级结构信息表明,BSA在Fe_3O_4纳米粒子表面存在构象变化和排列取向现象,反映在BSA接触材料后一些位点交联频率的改变。此纳米粒子表面蛋白的CXMS表征方法简单、快速,可提供蛋白在纳米材料上结构变化的化学交联的束缚特征,有望进一步应用于复杂蛋白体系与材料的相互作用研究。     

Pd/Ni异结构纳米催化剂的制备及其对甲酸氧化的电催化

通过两步还原法制备了Pd/Ni双金属催化剂.由于金属Pd原子在先行还原的Ni纳米粒子表面的外延生长以及其在Ni表面及Pd表面生长表现出的吉布斯自由能差异,最终导致了异结构Pd/Ni纳米粒子的形成.高分辨电子透射显微镜结果证实了异结构的存在,然而X射线衍射测量表明Pd/Ni纳米粒子具有类似于Pd的面心立方结构.制备的Pd/Ni纳米粒子与同等条件下合成的Pd纳米粒子相比对甲酸氧化呈现了更高的电催化活性,而且电催化稳定性也要明显优于纯Pd纳米粒子,证明Pd/Ni双金属催化剂是可选的直接甲酸燃料电池阳极催化剂.双金属催化剂对甲酸氧化电催化活性和稳定性增强可能是Ni原子的修饰改变了Pd粒子表面配位不饱和原子的电子结构所致.     

ITO负载内凹AuPd合金纳米粒子形状的电化学调控

运用电化学方波电位法,在氧化铟锡(ITO)透明导电膜玻璃基底上实现AuPd纳米粒子的形状控制合成.当固定方波下限电位0.30 V,上限电位分别为0.64和0.70 V时,分别制备出内凹三八面体(TOH)和内凹六八面体(HOH)AuPd合金纳米粒子.运用扫描电镜(SEM)、X射线能量散射谱(EDX)和电化学循环伏安法表征所制备的纳米粒子,结果表明所制备的AuPd纳米粒子在ITO上分散均匀,具有清晰的内凹三八面体和内凹六八面体的形状,Au:Pd元素比均接近3:1.但由于Au比Pd的表面自由能低,导致Au在AuPd合金纳米粒子表面富集.发现从合成的TOH AuPd合金纳米粒子出发,对其施加下限电位0.30 V、上限电位0.70 V的方波电位处理,可实现由TOH向HOH形状转变;延长方波电位处理时间仅改变AuPd合金纳米粒子的尺寸,但HOH形状保持不变.     

铁酸铋粉体:硝酸钾辅助水热合成的形貌调控及可见光催化性能(英文)

利用硝酸钾作为辅助矿化剂,采用水热法合成了不同尺寸和形貌的铁酸铋粉体,探索了硝酸钾的加入量对产物的尺寸和形貌的影响。采用X射线衍射、扫描电镜和透射电镜以及漫反射光谱对制备的铁酸铋粉体的相结构、微观形貌以及光吸收特性进行了表征。结果显示,随着尺寸的减小,粉体的吸收带边发生蓝移。可见光降解刚果红实验表明,粒径小的铁酸铋纳米粉体颗粒具有更好的可见光催化活性。     

GO/Fe3O4/有机胺复合材料的制备及对结晶紫染料的吸附性能

用改进的Hummers法制备了氧化石墨烯,用乙二胺、乙二胺与丁二胺/己二胺混溶来改性氧化石墨烯。用水热法制备了Fe3O4,并用物理混合法制备了GO/Fe3O4/有机胺的三元复合体系。用透射电镜、扫描电镜、红外光谱、热重分析、X射线衍射、VSM和XPS等对所制得的样品进行了结构表征和性能测试,研究了三元复合粒子对结晶紫染料的吸附性能及影响结晶紫染料吸附效果的因素。结果表明:所制备的Fe3O4的平均粒径约为200 nm,粒径分布均匀;复合物中GO为典型的片状结构,GO及有机胺的掺杂没有影响Fe3O4的尖晶石结构;复合物为超顺磁性,Ms为53.0 emu·g~(-1)。吸附结果表明:石墨烯/Fe3O4/有机胺的三元复合材料对结晶紫染料的最大吸附量随浓度增大而增大,而吸附结晶紫染料的移除率却随结晶紫染料浓度增大而减小,并趋向一定值;乙二胺和己二胺混溶比例为5∶1的GO/Fe3O4复合材料吸附性能最佳:结晶紫浓度为400 mg·L~(-1),最大吸附量为164.3 mg·L~(-1)。     

5-氨基间苯二甲酸敏化LaF_3∶Tb发光纳米粒子的合成及其细胞成像

以稀土硝酸盐、NH4F、5-氨基间苯二甲酸(AIPA)和柠檬酸为反应原料,水热法一锅合成了水溶性良好的AIPA敏化LaF3∶Tb(AIPA-LaF3∶Tb)纳米粒子。采用X射线衍射、透射电镜、红外光谱等对粒子进行了表征。结果表明,合成粒子为六方晶系的LaF3晶体,粒径为8 nm左右,粒子表面包覆了AIPA。测试了合成粒子的发光性能,其最大激发和发射波长分别为348和547 nm,粒子中存在着AIPA向Tb3+的能量传递。和LaF3∶Ce,Tb粒子相比,AIPA-LaF3∶Tb粒子的激发波长红移了94 nm,发光强度增大。在合成的基础上,对AIPA-LaF3∶Tb粒子进行了氨基化修饰,然后将氨基化粒子和兔抗人CEA抗体偶联,最后用偶联了抗体的AIPA-LaF3∶Tb粒子对HeLa细胞进行免疫标记与成像。     

Preparation and characterization of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>composite particles

Using Fe₃O₄ nano-particles as seeds, a new type of Fe₃O₄/Au composite particles with core/shell structure and diameter of about 170 nm was prepared by reduction of Au³⁺ with hydroxylamine in an aqueous solution. Particle size analyzer and transmission electron microscope were used to analyze the size distribution and microstructure of the particles in different conditions. The result showed that the magnetically responsive property and suspension stability of Fe₃O₄ seeds as well as reduction conditions of Au³⁺to Au⁰are the main factors which are crucial for obtaining a colloid of the Fe₃O₄/Au composite particles with uniform particle dispersion, excellent stability, homogeneity in particle sizes, and effective response to an external magnet in aqueous suspension solutions. UV-Vis analysis revealed that there is a characteristic peak of Fe₃O₄/Au fluid. For particles with d(0.5)=168 nm, the λmax is 625 nm.     

Synthesis and luminescence properties of nanocrystalline YVO4:Eu

Nanocrystalline YVO₄:Eu³⁺ was synthesized by direct precipitation reaction, which was then annealed at different temperatures. The results of XRD showed that nanocrystalline YVO₄:Eu³⁺ could be obtained in solution at 60 °C, and the mean particle sizes of samples are increased as annealing temperature is increased. The results of TEM exhibit that the sizes of samples are around 5-30 nm. Studies on the excitation spectra show that there are a large number of the structural distortions in smaller particles. By analyzing line splitting patterns and peaks broadening in the emission spectra, we consider that the deviations in intensity patterns of ⁵D₀-⁷F₂ are affected by distortions of crystal lattice. Some abnormal behaviors can be attributed to higher ratio of surface to volume, which lead to the different local symmetry environment of Eu³⁺ ions on the surface.     

Preparation of Au-TiO2 Hybrid Nano Particles in Silicate Film Made by Sol-Gel Method

TiO₂ nano particles with photo catalytic property were mixed with silica alkoxides solution with HAuCl₄/4H₂O. STS02 (purchased from Ishihara Sangyo Kaisha, Ltd.) was used as TiO₂ nano particles. The average size of TiO₂ nano particles was 7 nm in diameter. The gel film coated on glass substrate was heated and then HAuCl₄/4H₂O was thermally reduced at 390 degree. The coated silica gel film doped with HAuCl₄/4H₂O and TiO₂ nano particles was turned into light blue from colorless gel film after heat treatment. The optical absorption spectrum showed the absorption peak of the film heated at 390 degree shifted to at about 650 nm compare to SiO₂ film doped with Au nano particles without TiO₂ nano particles that had absorption peak at 542 nm. On the other hand, the film formed from coating solution incorporated TiAA (titanium tetraisopropoxide chelated by acetyl acetone) as TiO₂ source instead of TiO₂ nano particles had absorption peak at 550 nm. That means there was no effect on formation of Au nano particles when TiAA was incorporated. The average size of the particles was found to be about 23 nm in diameter by TEM observation. Furthermore EDX (Energy Dispersive X-ray Fluorescence Spectrometer) analysis of nano particles in the film indicated that Au-TiO₂ nano hybrid particles were formed. Simulation results also supported that the size in diameter of Au nano particles had little influence on the absorption coefficient of the silica film doped with Au nano particles.     

Transparent oxyfluoride glass ceramics co-doped with Er and Yb - Crystallization and upconversion spectroscopy

Transparent glass ceramics in the system SiO₂-B₂O₃-PbO-CdO-PbF₂-CdF₂-YbF₃-ErF₃ showing infrared to visible anti-Stokes (upconversion) luminescence are studied in the present work. The glass compositions have been optimized in order to reduce the melting temperature and, hence, to obtain laboratory scale samples with good optical quality. Erbium-doped nanoscale Pb₄Yb₃F₁₇ crystals are precipitated in the precursor glasses during annealing at temperatures 30-40 K above T_g. A kinetically self-constrained growth explains the nano sizes of the crystals. Both the Stokes and anti-Stokes luminescence spectra of glasses could be explained with clustering of the Yb³⁺ and Er³⁺ ions in fluorine-rich regions. At the annealing temperature these regions act as nucleation precursors. The crystal growth further enhances the local concentration of these ions. Consequently, a series of energy transfer and energy cross relaxation processes occurs between adjacent rare earth ions leading to the observed luminescence spectra of the glass ceramics studied.     

A Boron Doped Diamond Electrode Modified with Nano‐carbon Black for the Sensitive Electrochemical Determination of Chlorogenic Acid

An electrochemical method was developed for the sensitive determination of chlorogenic acid using a boron doped diamond electrode (BDDE) modified with nano‐carbon black (nano‐CB). The active surface areas were found to be 0.059 and 0.146 cm² for the unmodified BDDE, and nano‐CB/BDDE, respectively. Compared with a BDDE, the nano‐CB/BDDE exhibited a well‐defined redox couple for chlorogenic acid. In addition, the plot of the peak current response changing from a square root to a linear dependence on scan rate is attributed to the transition from planar diffusion to surface behaviour. The anodic and cathodic peak separations (ΔE_p) were 97 mV and 14 mV at BDDE and nano‐CB/BDDE, respectively. The decrease in ΔE_p at the proposed electrode indicated that the process of chlorogenic acid was greatly accelerated. Square wave voltammetry (SWV) exhibited a dynamic range in which the current versus the concentration of chlorogenic acid were linear from 2.0×10^?8 to 2.0×10^?6 M with a LOD of 4.1×10^?9 M (based on 3S_b/m). The nano‐CB modified BDDE provided improved electrochemical behavior, high electrocatalytic activity, high sensitivity and good reproducibility.     

Electrocatalytic Oxidation of Dopamine at a Nanocuprous Oxide‐Methylene Blue Composite Glassy Carbon Electrode

Cuprous oxide nanowhisker was prepared by using cetyltrimethyl ammonium bromide (CATB) as soft template, and was characterized by XRD and TEM methods. The electrochemical properties of nano‐Cu₂O and nano‐Cu₂O‐methylene blue (MB) modified electrode were studied. The experimental results indicate that nano‐Cu₂O shows a couple of redox peaks corresponding to the redox of Cu(II)/Cu(I), the peak currents are linear to the scan rates which demonstrate that the electrochemical response of Cu₂O is surface‐controlled. The composite nano‐Cu₂O‐Nafion‐MB modified electrode shows a trend of decrease of peak currents corresponding to the Cu (II)/Cu (I). However, the electrocatalytic ability of nano‐Cu₂O‐MB composite film to dopamine increases dramatically. At this composite electrode, dopamine shows a couple of quasireversible redox peaks with a peak separation of 106 mV, the peak current increases about 8 times and the oxidation peak potential decreases about 200 mV as compared to that at bare glassy carbon electrode. The peak currents change linearly with concentration of dopamine from 1×10^?7 to 3.2×10^?4 mol/L, the detection limit is 4.6×10^?8 mol/L. The composite electrode can effectively eliminate the interference of ascorbic acid and has better stability and excellent reproducibility.