Electrochemical preparation and characterization of gold-polyaniline core-shell nanocomposites on highly oriented pyrolytic graphite

A simple electrochemical method for the in situ preparation of homogeneously dispersed gold-polyaniline core/shell nanocomposite particles with controlled size on the highly oriented pyrolytic graphite(HOPG)was demonstrated.The HOPG surface was modified preferentially by covalent bonding of a two-dimensional 4-aminophenyl monolayer employing diazonium chemistry.AuCl4 -ions were attached to the Ar-NH2 termination and reduced electrochemically.This results in the formation of Au nuclei that could be further grown into gold nanoparticles.The formation of polyaniline as the shell wrap of Au nanoparticle was established by localized electro-polymerization.These core-shell nanocomposites prepared were characterized by AFM and cyclic voltammetry.The results show that the gold-polyaniline core-shell composites on HOPG have a mean particle size of 100 nm in diameter and the polyaniline shell thickness is about 15 nm.     

Preparation and characterization of Fe/SiO_2 core/shell nanocomposites

In a simple ethanol-water system,the magnetic α-Fe nanoparticles(with an average diameter of 10-40 nm)were prepared by reduction of Fe2 +using potassium borohydride in the presence of surfactant.Then the shell was formed by hydrolysis-condensation polymerization of tetraethylorthosilicate(TEOS)on the surface of the Fe particles.The samples were characterized by XRD,TEM,SAED,TG-DSC and VSM.The results indicate that a thin film of silica is coated on the surface of Fe particles through a Si-O-Fe bond.The coated shell of silica can effectively protect the Fe cores from being oxidized.     

Photochemical synthesis of bimetallic Au-Ag nanoparticles with "core-shell" type structure by seed mediated catalytic growth

The colloidal Au core/Ag shell structure composite nanoparticles were synthesized in PEG-acetone solution by photochemical route. The monodispersed Au nanoparticles with average diameter of 3.9 nm were used as growth seeds. The optical property of colloids and the sizes of composite nanoparticles were characterized when the molar ratio of Au to Ag ranges from 4 : 1 to 1 : 4. The results show that a composite nanoparticle structure similar to strawberry shape is formed at the molar ratio of Au to Ag from 4 : 1 to 1 : 1; the composite nanoparticles consisting of a core of Au and shell of Ag were generated at the 1: 4 molar ratio, having a striking feature of forming interconnected network structure.     

直流电弧等离子体制备NiO包覆Ni纳米颗粒

采用直流电弧等离子体技术制备NiO包覆Ni纳米颗粒,对初产物经过钝化处理得到有氧化膜保护的NiO包覆Ni纳米颗粒.采用高分辨透射电子显微镜(HRTEM)、X射线衍射(XRD)、透射电子显微镜(TEM)、选区电子衍射(SAED)、热重和差示扫描量热分析仪(TGA/DSC)以及傅里叶变换红外光谱 (FTIR)等手段对试样的成分、表面组成、形貌、晶体结构、粒度、红外吸收性能和氧化特性进行了分析.结果表明:经过表面钝化处理的NiO包覆Ni纳米颗粒具有明显的核-壳结构,内核为纳米Ni,外壳为NiO氧化物;颗粒呈球形,粒度均匀,分散性良好,粒径分布在20～70 nm范围,平均粒径为44 nm,壳层氧化膜的厚度为5～8 nm;壳核结构可防止纳米Ni颗粒的进一步氧化和团聚,且使红外吸收峰发生蓝移.     

Preparation and catalytic activity of CO-resistant catalyst core-shell Au@Pt/C for methanol oxidation

Au@Pt core-shell nanoparticles were successfully synthesized by a successive reduction method and then assembled on Vulcan XC-72 carbon surface.Furthermore,its composition,morphology,structure,and activity towards methanol oxidation were characterized by UV-vis spectrometry,transmission electron microscopy (TEM),high-resolution TEM (HRTEM),X-ray diffraction (XRD),X-ray photoelectron spectroscopy (XPS),and cyclic voltammetry (CV).Results reveal that Au@Pt/C catalyst has better activity towards methanol oxidation than the pure platinum prepared under the same conditions.When the atomic ratio of Au to Pt in the prepared Au@Pt/C catalyst is 1∶2,this catalyst exhibits best electrocatalytic activity towards methanol oxidation in acidic media,and the peak current density on this catalyst is ～2.0times higher than that on Pt/C catalyst.The better catalytic activity of Au@Pt/C results from its better resistance to toxic CO than Pt/C because the CO oxidation on Au@Pt/C is 60 mV more negative than the case on Pt/C.     

Electroless synthesis of nano-structured gold particles using conducting polymer nanoparticles

In this study, gold nanoparticles were synthesized by electroless recovery of [AuCl₄]⁻ from an acidic aqueous solution using nano-structured conducting polymer, polypyrrole nanoparticles, as active surface. The formation of gold nanoparticles was confirmed by TEM, SEM and EDX measurements. The effects of the initial Au(III) concentration on the gold uptake was examined. The recovery capability and gold particle morphology prepared from polypyrrole nanoparticle were compared to that from cast PPy film counterpart.     

Preparation of ultrafine core-shell nickel spheres via self-sacrificial template

1 Introduction Ultrafine particles stand for granules with diameter less than 0.5 μm. For their extremely small size and large specific surface area, these sub-micron powders can be widely used as catalysts, adsorbents in the fields of chemistry, physics…     

化学镀制备玄武岩纤维/镍核壳结构及其表征

采用简单易行的化学镀方法，在较低的温度下制备出一种新型的玄武岩纤维／镍核壳结构。SEM、XRD、XPS分析结果表明，金属Ni颗粒吸附在玄武岩纤维表面，形成了一层均匀连续的镍壳层。通过对试验结果进行分析，得出了制备玄武岩纤维／镍核壳结构的最佳温度和pH值分别为50℃和10．0。文中对化学镀核壳结构的形成机理也进行了初步分析。     

醇热还原法制备纳米金属钌颗粒

报道了利用溶剂热工艺在乙醇溶液中制备胶态纳米金属钌颗粒的方法. 在120.℃热处理不同时间后, 观测到溶剂热还原反应形成不同颜色的中间体. 通过添加醋酸根稳定剂, 在乙醇溶剂中形成晶粒尺寸为3～6纳米的单分散金属钌颗粒. 通过该方法还合成了溴化十六烷基三甲铵(HTAB)包敷的晶粒尺寸为1～5纳米的金属钌粉体.     

阳极表面电沉积SrSO4涂层及生长机制

通过在EDTA(乙二胺四乙酸)络合SrSO4水溶液中进行电沉积的方法,在SS304基板上制备SrSO4涂层,通过扫描电镜(SEM)和X射线衍射仪(XRD)研究SrSO4晶体在电沉积过程中的生长规律。不锈钢阳极表面生成的SrSO4晶体在(210)晶面上出现了择优取向生长,而在(002)晶面上的生长受到抑制。SrSO4晶体在电沉积工艺中的生长过程主要受过饱和度控制。     

碳包覆氧化镍纳米颗粒制备与电化学性能研究

采用直流电弧放电等离子体技术制备了核壳结构碳包覆氧化镍纳米颗粒,并采用X射线衍射、高分辨透射电子显微镜、X射线能量色散分析谱仪和表面物理吸附仪等测试技术对样品的微观结构进行研究。并利用循环伏安法、恒电流充放电以及交流阻抗等技术研究其作为超级电容器电极材料的电化学性能。结果表明:直流电弧等离子体技术制备的碳包覆氧化镍纳米颗粒具有典型的核壳结构,内核为面心立方结构的氧化镍纳米颗粒,外壳为碳层。颗粒形貌主要为立方体结构,粒度均匀,分散性良好,粒径分布在30～70 nm范围,平均粒径为50 nm,外壳碳层的厚度为5 nm。碳包覆氧化镍纳米颗粒具有较高的比容量和良好的电化学活性。     

金核壳结构复合纳米颗粒在生物医学中的应用

核壳结构纳米材料是一种新型复合材料。贵金属金纳米核壳材料同时具有核和壳的性质,以及独特的光学、电学、催化性能和良好的生物相容性,因此在生物、化学、医学等领域具有巨大的应用价值。基于文献分析,综述了金及其核壳结构纳米复合颗粒在生物及医学上的应用,包括蛋白质、DNA、细菌和病毒的检测,以及肿瘤热疗、生物成像、生物传感、药物传递与释放等。并对完善制备技术以便更好地应用于临床进行了展望。     

单晶和多重栾晶纳米钯的可见光简易合成及其光学、电学性质

以氯化钯(PdCl2)为金属前驱体,利用简易可见光辅助法制备具有单晶和多重孪晶结构的钯纳米颗粒。结果表明,不同纳米结构的形成取决于还原速率的控制。与多重孪晶结构的钯纳米颗粒不同,单晶钯纳米粒子在可见光区域表现了表面等离子共振吸收峰。纳米钯粒子的电化学性质也采用循环伏安法进行了研究。通过比较单晶和多重孪晶钯纳米粒子氧化过程的电化学参数,表明多重孪晶钯纳米粒子对乙醇有较好的电催化活性和抗中毒能力。     

纳米金红石型TiO2沉积制备云母钛纳米复合材料及其光学性质

研究在片状绢云母表面直接沉积纳米金红石型TiO2制备云母钛纳米复合材料的方法。结果表明：在制备的云母钛中,金红石型TiO2良好地结合在光滑的绢云母表面上,沉积颗粒呈岛状分布,且分散均匀。随着TiO2含量的增加,形成致密的TiO2涂层。低温下热处理云母钛复合材料时,云母钛的白度、亮度及反射系数会随着金红石TiO2含量的增加而提高。云母钛复合物的反射系数随着TiO2的结晶性的提高而增加。     

电泳沉积制备TA有机复合涂层及其性能

目的通过便捷的共混方式在聚合物涂层中引入单宁酸(TA)锚定涂层,并改善涂层性能,提供新颖、简单的水性聚合物涂层固定及增强方法。方法通过简单的溶解分散方式将TA混入聚合物自组装成的纳米粒子分散液中,并采用阴极电泳在裸钛表面制备TA复合涂层。通过扫描电子显微镜对涂层形貌进行分析。通过超景深显微镜粗糙度测定、铅笔硬度测试、划格法附着力测试、浸泡法等,分别评价NP-TA_x复合涂层的厚度、粗糙度、硬度、附着力、耐久性等性质。最后通过防污测试评价TA复合对聚合物涂层防污性能的影响。结果成功合成了一种两性离子型水性聚合物PIDS,并自组装成纳米粒子,粒子呈球形形貌,粒径约184.8 nm。将纳米粒子与TA混合后,成功通过阴极电泳技术在钛表面制备复合涂层,通过调节沉积电压和时间可以获得不同厚度及表面微结构的涂层表面,涂层制备简便可控。制备NP-TA_x复合涂层后,TA提高了涂层的成膜性,涂层表面结构变得更为平整。NP-TA_x复合涂层的附着力由NP的2级增加到0级,硬度由NP的HB上升为1H,稳定性也大幅提升。通过防污测试表明,TA复合的两性离子涂层对蛋白质和细菌仍具有良好的防污效果,表明TA复合不会影响涂层现有性质。结论 TA与水性聚合物纳米粒子复合制备涂层,可大大提升聚合物涂层综合性能,是一种新颖、简单而且有效的水性聚合物涂层固定及增强途径。     

Cu纳米粉的制备及其导电性能研究

用电弧放电法在H2 Ar混合气氛下同时制备了气相稳定和液相稳定的Cu纳米粉,并用Cu纳米粉配制了导电浆料.用XRD,TEM,DSC-TG,化学分析等手段研究了粉体的相结构、表面组成、形貌、粒度和氧化特性.结果表明:气相稳定和液相稳定的Cu纳米颗粒具有壳核结构,核为纳米Cu,壳分别为氧化层和松油醇(C10H18O)分子层;粉体的平均粒度分别为80 nm和70 nm;在空气中,包覆在Cu纳米粒子表面的松油醇分子在190℃左右基本脱附和分解;Cu纳米粉导电浆料在烧结温度180～200℃、保温时间60～70 min、真空度1.33 Pa条件下可获得电阻率为(2.12～5.82)×10-4Ω·cm的导电膜.     

爆轰法制备碳包覆铁镍合金纳米颗粒及其表征

对掺杂硝酸铁和硝酸镍复合炸药前驱体,采用爆轰法合成碳包覆铁镍合金纳米颗粒。通过XRD,TEM,XRF,VSM等方法对合成的碳包覆合金纳米颗粒的形貌特征、结构组成及磁性行为进行了分析表征。结果表明,通过有效调整前驱体中金属源材料比例和碳材料组成,可爆轰合成较为完美的核壳结构碳包覆铁镍纳米颗粒,所得球形的纳米颗粒尺寸主要分布在10～60nm范围内且分散性较好,组成核主要由不同比例的铁镍元素构成,外壳层主要由石墨碳构成;由室温下磁性分析可知,该纳米颗粒表现出良好的超顺磁性。     

复合离子液体中恒电流电沉积制备Ir层研究

对BMIC+BMIBF4复合离子液体中利用恒电流电沉积的方法在Mo基体上制备Ir层进行了研究。利用扫描电子显微镜(SEM)和X射线光电子能谱仪(XPS)对Ir层的表面形貌和成分进行了分析。结果表明:在BMIC+BMIBF4+EG复合体系中可以电沉积制备平整致密的单质Ir层且影响因素较多,如温度、电流密度、主盐浓度及沉积时间等,且这些因素可调节的范围比较窄。通过对比各因素间的影响得出,在此复合体系中恒电流电沉积制备Ir层的优化工艺为Ir Cl3浓度50 g/L,电流密度1.0 m A/cm2,沉积温度90℃,沉积时间20 h。     

Synthesis and characterization of Pt-Pd nanoparticles with core-shell morphology: Nucleation and overgrowth of the Pd shells on the as-prepared and defined Pt seeds

In the present research, Pt-Pd core-shell nanoparticles based on the as-prepared and defined Pt-seed cores with well-controlled size and morphology were synthesized. Their characterizations were investigated by using UV-vis spectroscopy, transmission electron microscopy (TEM), and high resolution (HR)TEM measurements. The high resolution elemental mappings were performed in the operation of high angle annular dark field (HAADF) in conjunction with scanning (S)TEM mode and X-ray energy dispersive spectroscopy (XEDS). It is found that not only the Pt-Pd core-shell nanoparticles were formed, but also the nucleation, growth, and the separate formation of single Pd nanoparticles as well. Interestingly, the as-prepared Pt cores without the morphological changes were protected by the overgrowths of the Pd shells during the successive reduction of sodium tetrachloropalladate (II) hydrate. There were the co-existence of the Frank-van der Merwe (FM) layer-by-layer and Stranski-Krastanov (SK) island-on-wetting-layer growth modes of the Pd shells on the as-prepared Pt cores. It is predicted that the SK growth became the favorable growth mode in the formation of the Pd shells in the formation Pt-Pd core-shell nanoparticles.