Ag@SiO2复合纳米粒子的光化学还原法制备及表征

采用光化学还原法在大颗粒负载型SiO2表面上成功制备了负载型Ag@SiO2复合纳米粒子,利用透射电子显微镜、X射线衍射和紫外-可见分光光度计等分析方法对样品进行了表征.结果表明,球形银纳米粒子均匀分散于球形SiO2复合粒子表面,复合粒子粒径在150～180 nm,且颗粒均一、分散性好.银粒子的粒径在10～15 nm,样品中银粒子具有良好的面心立方结构,晶型很好,银粒子的等离子共振吸收的最大峰位于474 nm.     

CaO-P2O5-SiO2系统生物活性纳米粒子形貌和粒径分布影响因素探讨

制备了TritonX-100／正辛醇／环己烷／水微乳液,并研究了该微乳液系统稳定相行为与制备条件的关系。在稳定的微乳液系统中制备出CaO-P2O5-SiO2系统生物玻璃纳米粒子。采用X射线衍射、透射电子显微镜(TEM)和氮气吸附-解吸(BET)技术并结合测量统计法对样品的晶相、形貌、粒度进行表征。研究表明：粒子尺寸与工艺参数σ(表面活性剂与助表面活性剂的质量比)、ω(水与表面活性剂的摩摩尔比)、γ(水与醇盐的摩尔比)等有关。在σ为1．2,ω为6,7为8条件下可制得平均粒径为25nm的球形无定形态生物玻璃粒子。     

Preparation and properties of Ag modified Tb-doped ZrO2 nanotube arrays

Tb-doped ZrO₂ nanotube arrays were first prepared by anodizing the Zr-Tb alloys, and then Ag modified Tb-doped ZrO₂ nanotube arrays were obtained by loading Ag onto the Tb-doped ZrO₂ nanotube arrays through a thermal decomposition and formaldehyde reduction method. The influences of modification of Ag nanoparticles and AgNO₃ concentrations (0.0001, 0.001, 0.01?M) on the light absorption and photoluminescence (PL) properties were determined. Results show that Ag modified samples prepared by the thermal decomposition method exhibited a significant surface plasmon resonance(SPR) effect, and that the absorption and PL emission peaks were markedly enhanced. Compared to the Tb-doped ZrO₂ nanotube arrays, the PL intensity of the sample prepared using the thermal decomposition method in 0.001?M AgNO₃ solution was enhanced by 45.8%. The samples prepared by the formaldehyde reduction method displayed excessive deposition and oversizing of Ag particles, resulting in worsening of the properties of samples.     

聚砜/纳米TiO2有机-无机复合超滤膜的制备与表征

用阴离子表面活性剂改性的纳米TiO2,加入到聚砜铸膜液中,采用相转化法制备了分散均匀的聚砜/ TiO2复合超滤膜.通过测定纯水通量、对牛血清蛋白的截留率、水接触角、粘度、抗污染性、机械强度等实验,研究了不同TiO2加入量对膜的超滤性能和力学性能的影响.并在扫描电镜下观察了膜的表面与断面形态,测定了膜的孔密度、孔隙率、孔径及其分布,从而考察了添加纳米TiO2对膜微观结构的影响.结果表明,当纳米TiO2的加入量为2%(wt)时,膜的孔隙率增大,平均孔径减小;同时膜的性能得到了明显的改善,纯水通量提高了69%,同时膜的抗压强度和断裂强度也分别提高了50%和26.7%,并且膜的亲水性也明显增强,水接触角由72.1度降低到41.4度,从而使膜的抗污染性明显改善.但进一步增加TiO2的浓度(3%(wt)以上),膜的机械强度、亲水性和超滤性能反而下降.因此在聚砜膜中适量地添加纳米TiO2粒子,可明显改善膜的亲水性和力学性能,提高膜的通量,增强膜的抗污染能力,从而拓宽了膜的应用领域.     

Bi2Ti2O7‐based pyrochlore nanoparticles and their superior photocatalytic activity under visible light

Nanoparticles of Bi₂Ti₂O₇ pyrochlore were synthesized by a coprecipitation method. They exhibit a high visible‐light photoactivity for decolorization of a methyl‐orange dye solution in the presence of a sacrificial agent, H₂O₂. The same pyrochlore system with an Ag co‐catalyst showed even faster kinetics under only visible light and an unprecedentedly high photoactivity in the UV range.     

表面修饰氧化亚铅纳米颗粒的制备及其抗磨性能研究

以硬脂酸铅为单源前驱体,成功制备出硬脂酸修饰的氧化亚铅纳米颗粒,用透射电子显微镜、X-射线粉末衍射仪、红外光谱仪等仪器对其进行了结构表征,并在四球摩擦试验机上测试了其抗磨性能。结果表明:所制备的Pb2O纳米颗粒大小均匀,表面修饰层与纳米颗粒表面之间发生化学键合作用,其作为润滑油添加剂具有良好的抗磨能力。     

Synthesis,structural, magnetic and NO2 gas sensing property of CuO nanoparticles

Cupric oxide (CuO) nanoparticles are synthesized by the oxidation of Cu/Cu₂O, which is obtained by the chemical reduction of Cu²⁺ ions with ascorbic acid. XRD pattern confirmed the formation of CuO, and FE-SEM image shows the clusters consisting of 25–30 nm sized particles. The band gap energy (3.7 eV) from optical absorption spectra is blue shifted to that of bulk values. The Néel temperature, T_N ≈ 230 K for paramagnetic to antiferromagnetic transition was clearly seen. The magnetic hysteresis loops at 5 K showed weak ferromagnetic behavior. Based on the dc electrical conductivity (300–500 K), the apparent activation energy was 0.36 eV. The NO₂ gas sensing property of CuO was reasonably good in the temperature range of 200–300 °C, and the sensitivity increased with an increase in gas concentration but the effect of temperature is marginal.     

Silicothermic synthesis of phase-pure HfB2 fine powder

Phase pure and nano-sized hafnium diboride (HfB₂) fine powder was prepared via a novel sustainable silicothermic route at 1100°C from inexpensive raw materials HfO₂, Na₂B₄O₇ and Si. By introducing sodium oxysalts as source of Na₂O into the batch mixtures, the SiO₂/ Na₂O modulus in the melt were reduced from 5:1 to 2:1, and the original water-insoluble byproduct SiO₂ was taken by the melt at test temperature and converted into water soluble sodium silicate (Na₂Si₂O₅) which was easily removed from the reacted mass via simple hot water washing. Consequently, the aqua sodium silicate could be readily recycled and used as a precursor for preparing many other valuable materials due to absence of foreign salts (eg halides, especially in the molten salt-assisted synthesis process) in the synthesis process, and the relevant environmental concerns could be alleviated. Using excessive amount of 20 wt% Si and 15 wt% Na₂B₄O₇ as compensation for the evaporation loss of silicon, in the form of SiO (g), and B₂O₃ in the reduction process, a high reaction extent was achieved and HfO₂ and Na₂B₄O₇ were completely converted into HfB₂ at 1100°C.     

Preparation of calcined hydrotalcite/TiO2-Ag composite and enhanced photocatalytic properties

A series of calcined hydrotalcite/TiO₂-Ag (HTC/TiO₂-Ag) composites with different silver (Ag) contents were successfully prepared and investigated as a catalyst for the photodegradation of phenol using UV–vis light (λ>300 nm). The Ag nanoparticles were deposited on the surface of TiO₂ (TiO₂-Ag) through photodeposition method. The TiO₂-Ag nanoparticles were supported on hydrotalcite (HT) by the co-precipitation method at variable pH (HT/TiO₂-Ag), and then calcined at 500 °C to obtain the HTC/TiO₂-Ag composites. The composites were characterized by inductively coupled plasma mass spectrometry (ICP-MS), N₂ adsorption/desorption (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and diffuse reflectance spectra (DRS). Results show that there is an optimum silver ratio to obtain the highest photocatalytic performance in the HTC/TiO₂-Ag photocatalyst which is 2 wt%, and is assigned as HTC/TiO₂-Ag(2). The association of silver nanoparticles on TiO₂ enhanced photocatalytic activity of the bare semiconductor composite. Only 56% of phenol was photodegraded when photodegradation was performed with HTC/TiO₂, whereas ~100% was photodegraded using HTC/TiO₂-Ag(2). The data gathered from the photocatalytic degradation of phenol were successfully fitted to Langmuir-Hinshelwood model, and can be described by pseudo-first order kinetics. The results showed the HTC/TiO₂-Ag(2) as efficient photocatalyst, low cost, separable from solution by sedimentation, and reusable. The superior performance of HTC/TiO₂-Ag(2) composite photocatalyst may be attributed to the synergic catalytic effect between silver and TiO₂, dispersion of TiO₂-Ag(2) nanoparticles supported on calcined hydrotalcite, and the calcined hydrotalcite like photocatalyst.     

油溶性二硫化钼纳米微粒的制备及抗磨性能

通过共沉淀法制备出Py DDP表面修饰的二硫化钼纳米微粒。采用FT-IR、TEM、元素分析对产物组成和结构进行表征,并考察了其在有机溶剂中的分散性。结果表明:所得表面修饰Mo S2纳米微粒尺寸在30nm~50nm之间,其在氯仿、丙酮和基础油中具有良好的分散性。利用四球极压抗磨试验考察了其摩擦学性能,磨损试验结果表明表面修饰的Mo S2纳米微粒具有良好的抗磨、减摩性能。     

Development of an amperometric immunosensor based on TiO2 nanoparticles and gold nanoparticles

A highly hydrophilic, non-toxic and conductive TiO₂ nanoparticles/gold nanoparticles bilayer films as immobilization matrix via self-assembly (SA) and deposition method was prepared on a gold electrode. Subsequently, positively charged horseradish peroxidase (HRP) was assembled onto the bilayer films, which provided an interface to assemble gold nanoparticles for immobilization of carcinoembryonic antibody (anti-CEA). Finally, HRP was used to block sites against non-specific binding. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were applied to characterize the electrochemical properties of the SA process. The CVs reduction current of the immunosensor decreases linearly in two concentrations ranges of CEA from 0.3 to 10 ng/ml and from 10 to 80 ng/ml with a detection limit of 0.2 ng/ml in presence of 0.7 mM H₂O₂ in analyte solution. Effects of deposition time, pH of working buffer, temperature and incubation time were also explored for optimum analytical performance by using the amperometric method. Moreover, the proposed immunosensor exhibited good accuracy, high sensitivity, long-term stability and made it to determine CEA in serum samples with satisfactory results.     

普鲁士蓝类纳米粒子的合成及其在双氧水检测中的应用

普鲁士蓝及其衍生物在具有优良的电化学性能、高稳定性等特点,在电化学领域发挥着重要的作用。文章用微乳法制备了Co-Fe普鲁士蓝类纳米粒子,并对其进行红外、电镜表征,发现其粒径均匀、呈立方状。同时,以此纳米粒子制备的修饰电极,对双氧水进行了检测,结果表明其电流的变化量与双氧水浓度的对数在0.48～5.74μmol·L-1范围内有线性响应。     

Gd,B共掺杂改性TiO_2纳米颗粒的可见光光催化活性

采用溶胶-凝胶法制备了Gd和B共掺杂的TiO2纳米颗粒,研究了TiO2纳米颗粒在可见光下的光催化活性。应用XRD、TEM和UV-Vis等手段对TiO2纳米颗粒的物相、粒径、形貌及光学性能进行了表征。结果表明,掺杂可以抑制TiO2晶粒增长,阻碍TiO2由锐钛矿相向金红石相的转变。紫外-可见吸收光谱显示,共掺杂纳米颗粒在可见光区吸收有较强提高,共掺杂离子以协同作用拓展TiO2光谱响应,使吸收带产生红移,提高光生载流子的分离效率。光催化降解实验表明,共掺杂TiO2纳米颗粒有很高的可见光光催化活性,以500℃热处理的共掺杂摩尔比为0.005 Gd和0.04 B的TiO2纳米颗粒光催化效果最好,在可见光下对甲基橙的降解率为98.9%。     

石墨烯负载纳米银的制备及其对H2O2的电化学检测

采用改进的Hummers法制备了氧化石墨烯（GO）,然后以水合肼作为还原剂,并控制反应的pH=10来制备还原氧化石墨烯（RGO）。采用化学还原法,以石墨烯为载体,以乙酰丙酮银为前体,以硼氢化锂四氢呋喃溶液为还原剂将银离子还原,制备了石墨烯负载纳米银复合材料。通过X 射线粉末衍射（XRD）、傅里叶变换红外光谱（FTIR）和透射电子显微镜（TEM）等表征方法证明了石墨烯上负载的银纳米颗粒结晶良好、尺寸均一、分布均匀,其中银纳米颗粒直径约为8nm。通过循环伏安和计时电流技术对石墨烯负载纳米银复合材料进行电化学测试,结果表明,石墨烯负载纳米银复合材料对过氧化氢的还原具有良好的电催化活性。以此复合纳米结构构建的过氧化氢传感器测试过氧化氢浓度的线性范围为0.1～62.3mmol/L（R=0.990）,检出限为0.017mmol/L（S/N=3）,响应时间小于2s。     

复合（SiO2-CdTe QDs）/SiO2编码荧光纳米颗粒的制备及应用

首先制备了表面氨基化的SiO2纳米颗粒,再分别将发绿色和红色荧光的CdTe QDs按比例组装于其表面,最后,用SiO2包覆SiO2-CdTe QDs纳米颗粒,实现了多步制备复合(SiO2-CdTe QDs)/SiO2编码荧光纳米颗粒。(SiO2-CdTe QDs)/SiO2编码荧光纳米颗粒不仅化学、光学性能稳定,而且还有利于与生物基团结合。另外,探讨了复合(SiO2-CdTe QDs)/SiO2编码荧光纳米颗粒与血红蛋白质结合的情况。从而为复合(SiO2-CdTe QDs)/SiO2编码荧光纳米颗粒作为生物探针在生化分析的应用奠定了一定的基础。     

纳米Al_2O_3表面接枝聚合改性的研究

为改善纳米Al2O3粒子在聚合物中的分散状况,本工作先在粒子表面引入双键,然后通过溶液自由基引发接枝单体丙烯酰胺和苯乙烯在Al2O3粒子表面的聚合,使接枝物与纳米粒子之间形成化学键合。系统研究了投料方式、引发剂浓度、单体浓度、反应时间等对接枝效果的影响,为调控纳米粒子表面的化学性质提供依据。     

A synergistic effect of nano‐Tio2 and graphite on the tribological performance of epoxy matrix composites

The influence of incorporated 300 nm TiO₂ (4 vol %), graphite (7 vol %), or combination of both fillers on the tribological performance of an epoxy resin was studied under various sliding load (10–40 N) and velocity conditions (0.2–3.0 m/s). Mechanical measurements indicated that the incorporation of TiO₂ significantly enhanced the flexural and impact strength of the neat epoxy and the graphite including epoxy. Tribological tests were conducted with a cylinder‐on‐flat testing rig. The incorporation of nano‐TiO₂ significantly improved the wear resistance of the neat epoxy under mild sliding conditions; however, this effect was markedly diminished under severe sliding conditions (high velocity and normal load). Nano‐TiO₂ reduced the coefficient of friction only under severe sliding conditions. Graphite showed a beneficial effect in reducing the wear rate and the coefficient of friction of the neat epoxy. Compared to the nano‐TiO₂‐filled epoxy, the graphite‐filled epoxy showed more stable wear performance with the variation of the sliding conditions, especially the normal load. A synergistic effect was found for the combination of nano‐TiO₂ and graphite, which led to the lowest wear rate and coefficient of friction under the whole investigated conditions. The synergistic effect was attributed to the effective transfer films formed on sliding pair surfaces and the reinforcing effect of the nanoparticles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2391–2400, 2006     

Li2O-doped MgAl2O4 nanopowders: Energetics of interface segregation

Manufacturing nanoceramics is challenging owing to the instability of the grain size resulting from the high driving force toward growth associated with the interfaces. Nanometric ceramics of some oxides have exceptional mechanical and optical properties, eg, magnesium aluminate spinel (MgAl₂O₄). The production of these fully conformed ceramics requires a precursor powder, which generally contains sintering-promoting additives. Li salts are typically used as sintering promoters for MgAl₂O₄, but the interface stability associated with the segregation of the additive is poorly understood. In this study, MgAl₂O₄ samples containing 0-2.86 mol% Li ions were synthesized via a simultaneous-precipitation method in an ethylic medium and subsequently calcined at 800°C in air. The nanopowders exhibited only the MgAl₂O₄ phase, and the crystallite size was determined by the Li₂O concentration. The crystallite size was changed via the chemical modification of the interfaces by the segregation of Li ions. The solubility in the bulk material was very low at the fabrication temperature, and small amounts of Li ions saturated the bulk material and segregated to the grain boundaries (GBs), significantly stabilizing the grain–grain interface compared with the surface. The resulting powder was then aggregated further owing to the initial stage of sintering. The surface excess obtained via the selective lixiviation method confirmed that the segregation to the GBs was greater than that to the surface. Energetics calculations confirmed these results, indicating a high enthalpy of segregation at the GBs () compared with that at the surfaces (). The enthalpy of segregation together with the interface excess allowed us to estimate the reduction in the interface energy with Li⁺ segregation of 0.8% to the surface and 11.2% to the GBs. The Li⁺ segregation to the surfaces started by Al³⁺ substitution, and for powders with ≥1.8 mol% Li ions, Mg⁺² was preferentially substituted at the surfaces.     

水热合成二氧化钛纳米颗粒及光致发光性能研究

以价格较为低廉的钛酸丁酯为钛源,不同添加量的十六烷基三甲基溴化铵（CTAB）为模板剂,采用水热合成法制备二氧化钛纳米颗粒。利用氮吸附仪、扫描电子显微镜（SEM）、X射线衍射仪（XRD）、荧光光谱仪（PL）对材料进行结构分析及光致发光性能测试。结果表明,所制备的二氧化钛纳米材料均为锐钛矿结构,粒径较小的纳米颗粒堆积形成介孔结构。样品具有特殊的光致发光特性,由于纳米颗粒粒径大小不同,孔径大小不等使得光致发光特性的强度产生较大差异,发射峰位置产生明显红移。     

Effect of Co2+, Ni2+, Cu2+, or Zn2+ on properties of polyaniline nanoparticles

Uniform polyaniline (PANI) nanoparticles with typical sizes of about 50 nm were electropolymerized on indium tin oxide surfaces in the presence of Co²⁺, Ni²⁺, Cu²⁺, or Zn²⁺. According to shaping theory, we first suggest the reason forming PANI spherical particles. Their conductivity, UV‐vis spectra, FTIR spectra, X‐ray diffraction, and thermogravimetric analysis were investigated. The conductivities and crystallinity of PANI doped with these ions are higher than those of PANI doped with HCl (PANI/HCl). Both UV‐vis absorption spectra and FTIR spectra indicate the interactions between Co²⁺, Ni²⁺, Cu²⁺, or Zn²⁺ and PANI chains. TG analysis also shows that the thermal stability of PANI doped by Co²⁺, Ni²⁺, Cu²⁺, or Zn²⁺ is lower than that of PANI/HCl. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007