Article

Functional noble metal nanoparticle superlattices grown at interfaces.

Graduate School of Material Science, University of Hyogo, Hyogo 678-1297, Japan.
Physical Chemistry Chemical Physics (Impact Factor: 3.83). 11/2011; 13(43):19214-25. DOI: 10.1039/c1cp22279a
Source: PubMed

ABSTRACT Nanoparticle crystals or superlattices (SLs) are three dimensional arrangements of nanoparticles in the micrometre regime. In SLs, the particles are periodically arranged in a coherent long range order and hence they show collective properties. Various spectroscopic, scattering and imaging techniques have been used to understand the structure of self-assembled SLs. Extensive interest in particle SLs is due to the collective properties of the building blocks, which help us to understand the evolution in properties of organized structures. Controlling the assembly of such organized solids may open up new opportunities for fundamental studies as well as for engineering advanced materials with useful attributes. This review presents our efforts in creating SLs of noble metal nanoparticles and studies performed with those materials.

0 Bookmarks
 · 
113 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Three-dimensional (3D) superlattices of gold nanoparticles were prepared at an air/solution interface. The surface of the gold nanoparticles used is protected by N-acetylglutathione (NAG). Morphological studies revealed that the superlattices formed fivefold symmetric structures such as pentagonal rod, decahedron, and icosahedron, which were probably developed by multiple twinning. Moreover, high-resolution surface images of the superlattices in fivefold symmetry showed excellent ordered arrangements of nanoparticles with both close-packed and non-close-packed structures.
    The Journal of Physical Chemistry B 08/2006; 110(29):14040-5. · 3.61 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We have examined two different routes to construct highly ordered two- or three-dimensional (2D or 3D) superlattice structures from hydrophilic polydisperse mercaptosuccinic acid (MSA)-modified Ag nanoparticles of the average size of 2.5 nm. First, polydisperse particles were fractionized by the polyacrylamide gel electrophoresis (PAGE) method. Due to the size-dependent migration under the electric field, the particles were isolated into a series of gel bands and each band contained particles with significantly narrow size distribution. Subsequent to phase transfer into chloroform by cationic surfactant, long-range 2D superlattices were simultaneously formed on the substrate upon evaporation of chloroform. Second, 3D superlattices were directly grown at an air-water interface from the polydisperse bulk dispersion by diffusion of HCl vapor without any pretreatment for the size narrowing. The influence of diffusion rate of HCl was also studied. The achievement of 3D superlattices via this route was ascribed as a long-time self-correction process. Furthermore, it was revealed that the superlattice structures obtained by the above two procedures exhibited distinct features though the starting material was the same MSA-Ag nanoparticles. The surface distance of core between component particles, the orientation of particles inside the superlattice, and the process of superlattice formation were comprehensively studied. We confirmed that each growth process depended on a corresponding self-assembly mechanism.
    The Journal of Physical Chemistry B 01/2007; 110(48):24442-9. · 3.61 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Assembly of small building blocks such as atoms, molecules and nanoparticles into macroscopic structures--that is, 'bottom up' assembly--is a theme that runs through chemistry, biology and material science. Bacteria, macromolecules and nanoparticles can self-assemble, generating ordered structures with a precision that challenges current lithographic techniques. The assembly of nanoparticles of two different materials into a binary nanoparticle superlattice (BNSL) can provide a general and inexpensive path to a large variety of materials (metamaterials) with precisely controlled chemical composition and tight placement of the components. Maximization of the nanoparticle packing density has been proposed as the driving force for BNSL formation, and only a few BNSL structures have been predicted to be thermodynamically stable. Recently, colloidal crystals with micrometre-scale lattice spacings have been grown from oppositely charged polymethyl methacrylate spheres. Here we demonstrate formation of more than 15 different BNSL structures, using combinations of semiconducting, metallic and magnetic nanoparticle building blocks. At least ten of these colloidal crystalline structures have not been reported previously. We demonstrate that electrical charges on sterically stabilized nanoparticles determine BNSL stoichiometry; additional contributions from entropic, van der Waals, steric and dipolar forces stabilize the variety of BNSL structures.
    Nature 02/2006; 439(7072):55-9. · 38.60 Impact Factor

Full-text (2 Sources)

View
37 Downloads
Available from
May 23, 2014