Influence of capping ligands on the self-organizations of gold nanoparticles into superlattice from CTAB reverse micelles

Gold nanoparticles with size 3-10 nm (diameter) were prepared by the reduction of HAuCl4 in a CTAB/octane + 1-butanol/H2O reverse micelle system using NaBH4 as the reducing agent. The as-formed gold nanoparticle colloid was characterized by UV/vis absorption spectrum and transmission electron microscopy(TEM). Various capping ligands, such as alkylthiols with different chain length and shape, trioctylphosphine (TOP), and pyridine are used to passivate the gold nanoparticles for the purpose of self-organization into superstructures. It is shown that the ligands have a great influence on the self-organization of gold nanoparticles into superlattices, and dodecanethiol C12H25SH is confirmed to be the best ligand for the self-organization. Self-organization of C12H25SH-capped gold nanoparticles into 1D, 2D and 3D superlattices has been observed on the carbon-coated copper grid by TEM without using any selective precipitation process.

Electrocatalytic oxidation of dopamine by ferrocene in lipid film cast on a glassy carbon electrode

The ferrocene-lipid film electrode was successfully prepared by means of casting the solution of ferrocene and lipid in chloroform onto a glassy carbon (GC) electrode surface. Ferrocene saved in the biological membrane gave a couple of quasi-reversible peaks of cyclic voltammogram. The electrode displays a preferential electrocatalytic oxidation of dopamine (DA). The effect of electroccatalytic oxidation of DA depends on the solution pH and the negative charge lipid is in favor of catalytic oxidation of DA. The characteristic was employed for separating the electrochemical responses of DA and ascorbic acid (AA). The electrode was assessed for the voltammetric differentiation of DA and AA. The measurement of DA can be achieved with differential pulse voltammetry in the, presence of high concentration of AA. The catalytic peak current was proportional to the concentration of DA in the range of 1 x 10(-4)-3 x 10(-3) mol/L.

Improved size control of large palladium nanoparticles by a seeding growth method

A new approach to the preparation of large palladium nanoparticles with diameters between 25 and 100 nm is presented. In this approach PdCl42- ions are reduced on the surface of performed 12-nm-diameter gold "seeds'' by the introduction of ascorbic acid. The resultant particles exhibit improved monodispersity relative to previous work. Interestingly, these nanoparticles possess Au-Pd core-shell structures. The method can be scaled up to produce 50-110 mg of large palladium nanoparticles.

An organic-inorganic hybrid ultrathin film: preparation and characterization of copper phthalocyanine derivative-ferric oxide nanoparticles

A nanoparticulate ferric oxide-copper tris(2,4-di-tert-amylphenoxy)-8-quinolinolylphthalocyanine hybrid ultrathin film was constructed from alternate layers by the Langmuir-Blodgett technique. The composition, morphology and structure of the film were studied by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy, atomic force microscopy, small-angle X-ray diffraction, visible spectroscopy and polarized UV-Vis spectroscopy. All the above analyses suggest that the thin film is a kind of one-dimensional superlattice, composed of organic and inorganic components. The XPS data reveal that the nanoparticulate ferric oxide exists as an alpha-Fe2O3 phase in the films. Gas-sensing measurements show that the hybrid LB film has very fast response-recovery characteristics towards 2 ppm C2H5OH vapor.