Large scale, templateless, surfactantless route to rapid synthesis of uniform poly(o-phenylenediamine) nanobelts

We reported the interesting finding that large scale uniform poly(o-phenylenediamine) nanobelts with several hundred micrometers in length, several hundred nanometers in width, and several ten nanometers in height can be rapidly yielded from an o-phenylenediamine-HAuCl4 aqueous solution without the additional introduction of other templates or surfactants at room temperature.

One-step preparation and characterization of poly(propyleneimine) dendrimer-protected silver nanoclusters

Highly stable silver nanoclusters with narrow size distribution have been prepared by heating a third-generation poly(propyleneimine) dendrimer/AgNO3 aqueous solution without the additional step of introducing other reducing agents and protect agents. UV-vis absorption, transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), and X-ray diffraction (XRD) have been used to characterize the resulting products. The as-obtained sample was in coexistence of Ag and Ag2O. It also suggested that increasing temperature resulted in both the decrease in number of small particles and the increase in size of large particles.

Two- and three-dimensional Au nanoparticle/CoTMPyP self-assembled nanotructured materials: Film structure, tunable electrocatalytic activity, and plasmonic properties

Two- and three-dimensional Au nanoparticle/[tetrakis(N-methylpyridyl)porphyrinato]cobalt (CoTMPyP) nanostructured materials were prepared by "bottom-up" self-assembly. The electrocatalytic and plasmonic properties of the Au nanoparticle/CoTMPyP self-assembled nanostructured materials (abbreviated as Au/CoTMPyP SANMs) are tunable by controlled self-assembly of the An nanoparticles and CoTMPyP on indium tin oxide (ITO) electrode. The electrocatalytic activity of the Au/CoTMPyP SANMs can be tuned in two ways. One way is that citrate-stabilized An nanoparticles are positioned first on ITO surface with tunable number density, and then positively charged CoTMPyP ions are planted selectively on these gold sites. The other way is that An nanoparticles and CoTMPyP are deposited by virtue of layer-by-layer assembly, which can also tune the amount of the as-deposited electrocatalysts. FE-SEM studies showed that three-dimensional SANMs grow in the lateral expansion mode, and thermal annealing resulted in both surface diffusion of nanoparticles and atomic rearrangement to generate larger gold nanostructures with predominant (I 11) facets.

Nanocomposite multilayer film of preyssler-type polyoxometalates with fine tunable electrocatalytic activities

Through layer-by-layer (LBL) assembly technique, iron oxide (Fe3O4) nanoparticles coated by poly (diallyldimethylammonium chloride) (PDDA) and Preyssler-type polyoxometalates (NH4)(14)NaP5W30O110.31H(2)O (P5W30) were alternately deposited on quartz and ITO substrates, and 4-aminobenzoic acid modified glassy carbon electrodes. Thus-prepared multilayer films were characterized by UV-visible spectroscopy, X-ray photoelectron spectroscopy, and cyclic voltammetry. It was proved that the multilayer films are uniform and stable. And the electrocatalytic activities of the multilayer films can be fine-tuned by adjusting the assembly conditions in the LBL assembly process, such as the pH of the assembly solution. The multilayer films fabricated from P5W30 solutions dissolved in 0.1 M H2SO4 exhibit high electrocatalytic response and sensitivity toward the reduction of two substrates of important analytical interests, HNO2 and IO3- whereas the films assembled with P5W30 solutions dissolved in 1.0 M H2SO4 show remarkable electrocatalytic activity for the hydrogen evolution reaction (HER). Furthermore, the electrocatalytic properties of the HER of the latter film can be obtained from the former film upon exposure to 1.0 M H2SO4 for several hours.

Immobilization of the nanoparticle monolayer onto self-assembled monolayers by combined sterically enhanced hydrophobic and electrophoretic forces

The immobilization of surface-derivatized gold nanoparticles onto methyl-terminated self-assembled monolayers (SAMs) on gold surface was achieved by the cooperation of hydrophobic and electrophoretic forces. Electrochemical and scanning probe microscopy techniques were utilized to explore the influence of the SAM's structure and properties of the nanoparticle/SAM/gold system. SAMs prepared from 1-decanethiol (DT) and 2-mercapto-3-n-octylthiophene (MOT) were used as hydrophobic substrates. The DT SAM is a closely packed and organized monolayer, which can effectively block the underlying gold and inhibit a variety of solution species including organic and inorganic molecules from penetrating, whereas the MOT monolayer is poorly packed or disorganized (because of a large difference in dimension between the thiophene head and the alkylchain tail) and permeable to many organic probes in aqueous solution but not to inorganic probes. Thus, the MOT monolayer provides a more energetically favorable hydrophobic surface for the penetration and adsorption of organic species than the DT monolayer.

Unique structure and photoluminescence of Au/CdTe nanostructure materials

Unique nanostructure materials with highly ordered spherical aggregates have been obtained by self-organization of single CdTe nanocrystals using gold nanoparticles as seeds, and a red shift of the photoluminescence peak was observed.

Noncovalent functionalization of multiwalled carbon nanotubes: Application in hybrid nanostructures

We developed a reproducible, noncovalent strategy to functionalize multiwalled carbon nanotubes (MWNTs) via embedding nanotubes in polysiloxane shells. (3-Aminopropyl)triethoxysilane molecules adsorbed to the nanotube surfaces via hydrophobic interactions are polymerized simply by acid catalysis and form a thin polysiloxane layer. On the basis of the embedded MWNTs, negatively charged gold nanoparticles are anchored to the nanotube surfaces via electrostatic interactions between the protonated amino groups and the gold nanoparticles. Furthermore, these gold nanoparticles can further grow and magnify along the nanotubes through heating in HAuCl4 aqueous solution at 100 degrees C; as a result these nanoparticles are joined to form continuous gold nanowires with MWNTS acting as templates.

In situ synthesis and characterization of multiwalled carbon nanotube/Au nanoparticle composite materials

An effective and facile in Situ reduction approach for the fabrication of carbon nanotube-supported Au nanoparticle (CNT/Au NP) composite nanomaterials is demonstrated in this article. Linear polyethyleneimine (PEI) is ingeniously used as both a functionalizing agent for the multiwalled carbon nanotubes (MWNTs) and a reducing agent for the formation of An NPs. This method involves a simple mixing process followed by a mild heating process. This approach does not need the exhaustive surface oxidation process of CNTs. The coverage of Au NPs on CNTs is tunable by varying the experimental parameters, such as the initial molar ratio of PEI to HAuCl4, the relative concentration of PEI and HAUCl(4) to MWNTs, and the temperature and duration of the heat treatment. More importantly, even the heterogeneous CNT/Au composite nanowires are obtainable through this method. TEM, XPS, and XRD are all used to characterize the CNT/Au composite materials. In addition, the optical and electrocatalytic properties are investigated.

Glycyl glycine templating synthesis of single-crystal silver nanoplates

We describe the small-biomolecule ( glycyl glycine)-directed synthesis of single-crystalline silver nanoplates, and different experimental conditions have been explored for a more thorough understanding of the growth mechanism. The yield of silver nanoplates relative to the total number of nanoparticles formed was as high as similar to 80%. It was found that the ratio of glycyl glycine to AgNO3 was the key to forming Ag nanoplates.

Rapid synthesis of cubic Pt nanoparticies and their use for the preparation of Pt nanoagglomerates

We report the synthesis of hexadecyltrimethylammonium bromide (CTAB)-stabilized cubic Pt nanoparticles by NaBH4 reduction of H2PtCl6 in aqueous CTAB solution. These Pt nanoparticles (average size of 7 nm) were well dispersed in aqueous solution and stable at least for 2 months. Addition of a trace amount of AgNO3 can alter the morphology of these Pt nanoparticles. More interestingly, the as-prepared uniform Pt nanoparticles were further developed into bigger Pt nanoagglomerates (similar to 20 to 47 nm) by a seed-mediate growth process. Dentritic and spherical Pt nanoagglomerates can be synthesized by altering the incubation time and their size can be tuned by controlling the amount of the seeds added.

Aggregation-based fabrication and assembly of roughened composite metallic nanoshells: Application in surface-enhanced Raman scattering

This paper reports an aggregation-based method for the fabrication of composite Au/Ag nanoshells with tunable thickness and surface roughness. It is found that the resultant roughened composite Au/Ag nanoshells can attract each other spontaneously to form films at the air-water interface. Importantly, such films can be transferred onto the solid substrates without being destroyed and show excellent surface-enhanced Raman scattering (SERS) enhancement ability. Their strong enhancement ability may stem from the unique two-dimensional structure itself.

Metal-containing molecular wires and their electron transportation properties

Metal-containing conjugated bisthioester 1 was synthesized. It was fabricated into "gold electrode - molecular wires monolayers - gold nanoparticles" junction using self-assembly and nanoparticles deposition techniques. The junction is suitable for investigating the electron transportation property of molecular wires.

Small angle scattering characterisation of micellar systems and templated architectures

The work described in this thesis reports the structural changes induced on micelles under a variety of conditions. The micelles of a liquid crystal film and dilute solutions of micelles were subjected to high pressure CO2 and selected hydrocarbon environments. Using small angle neutron scattering (SANS) techniques the spacing between liquid crystal micelles was measured in-situ. The liquid crystals studied were templated from different surfactants with varying structural characteristics. Micelles of a dilute surfactant solution were also subjected to elevated pressures of varying gas atmospheres. Detailed modelling of the in-situ SANS experiments revealed information of the size and shape of the micelles at a number of different pressures. Also reported in this thesis is the characterisation of mesoporous materials in the confined channels of larger porous materials. Periodic mesoporous organosilicas (PMOs) were synthesised within the channels of anodic alumina membranes (AAM) under different conditions, including drying rates and precursor concentrations. In-situ small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM) was used to determine the pore morphology of the PMO within the AAM channels. PMO materials were also used as templates in the deposition of gold nanoparticles and subsequently used in the synthesis of germanium nanostructures. Polymer thin films were also employed as templates for the directed deposition of gold nanoparticles which were again used as seeds for the production of germanium nanostructures. A supercritical CO2 (sc-CO2) technique was successfully used during the production of the germanium nanostructures.