Papers by Keyword: Template Synthesis

Abstract: Pt/Ni multilayer nanowire arrays were successfully fabricated inside the nanochannels of anodic aluminum oxide template by pulse electrodeposition method. The morphologies of the Pt/Ni nanowires were analyzed, which revealed that these nanowires had smooth surface and uniform diameter of about 70 nm. The ferromagnetic Ni layers were separated periodically by Pt layers along the axis of the nanowires. Magnetization measurements on the Pt/Ni nanowire arrays revealed a stronger magnetic anisotropy with the easy axis parallel to the nanowires. Following electrochemical performance tests indicated that the Pt/Ni multilayer nanowires comprising Pt and Ni layers showed enhanced electrocatalytic activity for methanol oxidation, as compared with pure Pt nanowires.

Abstract: Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) is a ceramic perovskite-type oxide that has attracted growing attention due to its high catalytic activity, mixed ionic/electronic conductivity and giant magnetic resistance. Improvement in the properties of BSCF can be achieved by tailoring its architecture such as nanoparticles (powdered form), nanotubes or nanorods as these nanostructured materials posses high surface-to-volume ratios with high sensitivity to surface adsorption and reactions. However, most of the studies conducted by means of conventional solid-state reaction methods or with wet chemistry techniques regularly produced BSCF in loose powdered form, non-uniform and the particle size is hard to be controlled. Herein in this work, an investigation on a synthetic approach using highly ordered nanoporous anodic aluminium oxide (AAO) as a template, focusing on the fabrication of BSCF perovskite nanorods is demonstrated. Sol-gel method is used to prepare the BSCF precursor solution or sol followed by filling the AAO template with the sol at different immersion time of 1 hr, 12 hrs and 24 hrs. After the following drying and calcination steps, the morphological structure and composition of the synthesized BSCF nanorods inside the AAO templates are examined by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) analysis. The micrograph showed BSCF nanorods are successfully synthesized at immersion time of 24 hrs with the diameter of nanorods embedded in the AAO template is approximately 180 nm. The EDX analysis also confirmed the stoichiometry of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ. Possible formation mechanism of BSCF nanorods inside the AAO template is also discussed in this paper.

Abstract: Composite materials with Co (P) particles embedded into pores of silica and track etched polycarbonate membranes were fabricated by an electroless reduction. The magnetic and structural properties of the composite materials are characterized by scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometer. The macroscopic and local magnetic anisotropy of the Co (P) particles electroless deposited in the pores of the polycarbonate membrane and silica is studied. The composite materials with linear pores exhibit uniaxial magnetic anisotropy. The easy axis lies along the Co (P) rods, the shape anisotropy dominates over the intrinsic crystalline anisotropy. Information on local anisotropy field and the grain size was obtained from investigation of approach to saturation magnetization law. The local anisotropy field for all the samples depends on P content. For Co (P) rods the local anisotropy value is also determined by nominal pore sizes. It was found that the investigated Co (P) rods is nanocrystalline. The effects of different pores morphology on the FMR-spectra characteristics are studied.

Abstract: Intermetallic (Ni-Sn) nanoparticles are synthesized through a borohydride reduction with NaBH₄ in a mixture of aqueous solutions of NiCl₂.6H₂O and SnCl₂.2H₂O at mass ratio and Ni:Sn = 45:55. The ratio is chosen in accordance with the Ni-Sn binary system phase diagram. A "template" technique which involves borohydride reduction of intermetallic nanoparticles on a support (carbon foam, graphite, carbon powder) is also used. The samples which are Ni-Sn alloys and carbon-based nanocomposites are studied by scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. The samples are electrochemically tested as electrode materials in Li-ion batteries.

Abstract: Intermetallic (Cu-Sn) nanoparticles are synthesized through a borohydride reduction with NaBH4 in a mixture of aqueous solutions of CuCl2.2H2O and SnCl2.2H2O at mass ratio Cu:Sn = 3:2 applying a template technique with a support such as carbon foam. The ratio is chosen in accordance with the Cu-Sn binary system phase diagram. The reductive precipitation is carried out at room temperature and atmospheric pressure. Porous nanocomposites are obtained and studied by scanning and transmission electron microscopy (SEM/TEM), and X-ray diffraction (XRD) analysis. The electrochemical behavior of the synthesized Cu-Sn alloy and the C-based composites (С-foam/Cu-Sn alloy) as positive electrodes is also investigated in a Li-ion battery) using a computer controlled laboratory cycling equipment BA500 Series Battery Analyzer.

Abstract: Dendrimer used as template which can better control the size, shape and dispersion of the rare metal nanoparticles. In this paper, we comparatively studied the nanocomposites of the polyamidoamine dendrimer PAMAM/RE and hyperbranched poly (amine-ester) HPAE/RE (RE=La, Nd, and Eu) based on the molecular dynamics simulation method. It was theoretically discussed the feasibilities of the PAMAM and HPAE as templates, the results show that the system energies decreases and tends to be stable after the compositions of the template molecules PAMAM and HPAE with the rare metal atoms (La, Nd, and Eu). Among them, changes of bond stretching, bond angle bending energy and van der Waals play a key role to the potential changes. The radiuses of gyrations of the composite systems are all smaller than the corresponding template molecules. The molecular dynamic information obtained by using of molecular simulation can not only make a reasonable explanation for the macroscopic experimental phenomena, but also greatly promote the development and application of the dendrimers.

Abstract: To construct 3D ordered hierarchical materials, Si, Al and Ti colloids precursors were controlled prepared via dual template method in which the colloidal crystals and P123 acted as hard-template and soft-template, respectively. The results showed that ordered hierarchical SiO2, Al2O3 and TiO2 were successfully prepared. The difference of the structure of samples suggested that hydrolysis rate of the precursors play an important role on pore structure of the samples.

Abstract: Coal/ZnAl-Layered double hydroxides (ZnAl-LDHs) composites were synthesized via a co-precipitate method using Shenfu coal as a raw material. Effect of coal on the structure, morphology and thermal properties of coal/LDHs composites were investigated by XRD, FT-IR, SEM and DSC analysis methods. The results indicated that coal provided acidic functional groups as the interlayer anion of composites, and the mineral materials in coal made the structure of composites more complicated. The morphologies and particle sizes of composites were affected by the porosity and network characteristics of coal. Although exothermic behavior of coal weakened the endothermic efficiency of ZnAl-LDHs during the degradation process, the coal char on the surface of composites formed an insulation layer, which provided a synergistic fire retardant of ZnAl-LDHs in coal spontaneous combustion.

Abstract: Hollow TiO₂ nanospheres have been successfully prepared by templating the polymericmicelles of poly (styrene-b-[3-(methacryloylamino)propyl] trimethylammonium chloride- b-ethylene oxide) (PS-b-PMAPTAC-b-PEO), which shows a core-shell-corona structure in aqueous solutions. It was found that, in such system, the wall thickness of the hollow TiO₂ is fine tuned by varying the concentration of the TiO₂ precursor.

Abstract: Copper is one of the most important metals in modern electronic technology. Keeping in view its role in nanoelectronics, we have fabricated copper nanowires of diameters 100 and 200nm using Anodic Alumina and polymer membranes as templates. Electrodeposition technique based on the principle of electroplating was adopted for copper nanowire fabrication in an electrochemical cell designed in our laboratory. SEM micrographs are used to calculate the aspect ratio of nanowires. The morphology of nanowires shows some interesting features.