Sungho Park

The assembly properties of two- and three-component rod-like building blocks consisting of gold and polymer block domains have been investigated. These structures behave like mesoscopic amphiphiles and form a series of single-layer superstructures consisting of bundles, tubes, and sheets depending upon the compositional periodicity. Unlike molecular systems, the template used to initially synthesize them plays a critical role in the assembly process by prealigning them in a manner that facilitat

The voltammetric electrooxidation rates of formic acid, formaldehyde, and methanol in acidic electrolyte on carbon-supported platinum nanoparticle films with varying particle diameters (d) in the range of ca. 2−9 nm are examined with the objective of comparing the nanoparticle size sensitivity for these related yet distinct electrocatalytic processes. The reaction rates on the larger nanoparticles (d > 4 nm) are similar to those observed on polycrystalline Pt when normalized to the same microsco

The utilization of surface-attached gold nanoparticles as templates for generating Pt-group particles displaying near-optimal surface-enhanced Raman scattering (SERS) characteristics is described. Essentially epitaxial transition metal coatings down to the monolayer level can be prepared, most readily by the spontaneous replacement of an electrochemically deposited copper layer by the desired Pt-group metal. The and essentially pinhole-free nature of the coated nanoparticles is demonstrated from

Monte Carlo simulations of hydration water on the mica (001) surface under ambient conditions revealed water molecules bound closely to the ditrigonal cavities in the surface, with a lateral distribution of approximately one per cavity, and water molecules (interposed between K+ counter ions) in a layer situated about 2.5 A from a surface O along a direction normal to the (001) plane. The calculated water O density profile was in quantitative agreement with recent x-ray reflectivity measurements

The electrical properties of template-synthesized three- and four-component rodlike nanostructures consisting of metal and conducting polymer domains have been studied. These structures behave like nanometer-scale resistors and diodes, depending upon their compositions and spatial distribution of the different compositional blocks. In the two-component systems, the conducting polymer block dictates the electrical properties of the nanostructure, and the metal blocks act as leads to facilitate th

Electrode potential-dependent infrared spectra for carbon monoxide dosed onto carbon-supported platinum nanoparticle films, significant as commercial fuel-cell catalysts as well as of fundamental importance, are reported with the aim of elucidating their structure as a function of particle size. The need to acquire absolute unipolar, rather than bipolar, spectra by means of potential-difference infrared tactics for such nanoparticle films is demonstrated, given the broad asymmetric C−O stretchin

Spectra obtained by electrochemical infrared reflection absorption spectroscopy (EC-IRAS) for carbon monoxide (CO) adlayers formed by partial CO dosing on various ruthenium-decorated platinum nanoparticle films are reported. The need to achieve a well distributed rather than aggregated metal nanoparticle array is demonstrated, given that such nanoparticle aggregates induce complex dielectric behavior. The strategy here is to use an "organic glue matrix" (short chain SAMs) between the nanoparticl

Rapid eye movement (REM) sleep is a distinct, homeostatically controlled brain state characterized by an activated electroencephalogram (EEG) in combination with paralysis of skeletal muscles and is associated with vivid dreaming. Understanding how REM sleep is controlled requires identification of the neural circuits underlying its initiation and maintenance, and delineation of the homeostatic processes regulating its expression on multiple timescales. Soon after its discovery in humans in 1953

Recent 1H/2D isotopic-difference neutron diffraction experiments on interlayer water in the two-layer hydrates of Wyoming montmorillonite with Li+ or Na+ counterions have shown that the organization of the water molecules differs from that in the bulk liquid. Monte Carlo simulations were performed to investigate molecular mechanisms underlying these structural differences in terms of radial distribution functions for H−O and H−H spatial correlations. Our simulations of the first-order difference

Herein, we report a general synthetic pathway to various shapes of three-dimensional (3D) gold nanoframes (NFs) embedded with a Pt skeleton for structural rigidity. The synthetic route comprises three steps: site-specific (edge and vertex) deposition of Pt, etching of inner Au, and regrowth of Au on the Pt framework. Site-specific reduction of Pt on Au nanoparticles (NPs) led to the high-quality of 3D Au NFs with good structural rigidity, which allowed the detailed characterization of the corres

Magnetically separable gold-nanoparticle catalyst was prepared, and it showed excellent activity for chemoselective reduction of nitroarenes with hydrosilanes.

Metal elements occupy more than 70% of the positions in the periodic table, and their use has accelerated human civilization due to their invaluable chemical and physical characteristics. With the rapid development of metals, various structures of microscopic metal particles have been fabricated and investigated as functional materials in scientific research and practical applications. The phrase 'structure determines properties' has been widely acknowledged as a golden rule in chemistry and mat