High-quality ∼16 nm c-In2O3 nanoctahedra and ∼6 nm Pd spherical nanoparticles were synthesized via a high-temperature wet-chemical approach, and their electrophoretic mobilities in toluene were investigated, respectively. Opposite electrical charge-induced 2D binary nanoparticle superlattice patterns containing two such nanocomponents were prepared, for the first time. Three types of c-In2O3-skeleton-structure-contained assembly patterns were identified as well. It was further observed that the vertices of c-In2O3 nanoctahedra could have higher electrical charge density than that on edge or plane and the small Pd nanoparticles were "suspended" on the middle plane of the c-In2O3 nanoctahedra, apparently well above the substrate surface (support film) rather than sitting on it. The assembly structure study indicates that Coulomb forces resulted from the opposite electrical charges are the dominative driving forces to induce the formation of such nanoctahedra-nanospheres 2D binary nanoparticle superlattices.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectronic structure of ethynylthiophenesIgor Novak, Siu Choon Ng, Jiye Fang, Chup Yew Mok, and Hsing Hua HuangCite this: J. Phys. Chem. 1994, 98, 3, 748–751Publication Date (Print):January 1, 1994Publication History Published online1 May 2002Published inissue 1 January 1994https://pubs.acs.org/doi/10.1021/j100054a006https://doi.org/10.1021/j100054a006research-articleACS PublicationsRequest reuse permissionsArticle Views264Altmetric-Citations8LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts
Loaded dice: High-quality and similarly sized Pt3Co and Pt nanocubes were prepared by gradually reducing metal precursors at high temperatures. Cyclic voltammetric and chronoamperometric results show a much higher methanol oxidation current density on Pt3Co nanocubes (see picture). The enhanced catalytic activity was explained by the slower and weaker adsorption of CO onto Pt3Co. Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
Abstract A facile, reliable, and robust synthetic method to prepare high‐quality Pt 3 Fe nanocubes is reported. Results of investigation on these Pt 3 Fe nanocubes in shape‐/size‐distribution, crystallinity, structural characteristics, compositions, electrochemical activity towards small organic molecule oxidation as well as capability of assembling into simple cubic supercrystals are presented, and a possible formation mechanism of the cubic nanocrystals at high temperature in oleylamine/oleic acid solution is also proposed. This study indicates that the catalyst performance may be improved by controlling the shape of particles.
DEP is one of promising techniques for positioning nanomaterials into the desirable location for nanoelectronic applications. In contrast, the lithography technique is commonly used to make ultra‐thin conducting wires and narrow gaps but, due to the limit of patterning resolution, it is not feasible to make electrical contacts on ultra‐small nanomaterials for a bottom‐up device fabrication. Thus, integrating the lithography and dielectrophoresis, a real bottom‐up fabrication can be achieved. In this work, the device with the nanogap in between two nanofinger‐electrodes is made using electron‐beam lithography from top down and the ultra‐small nanomaterials, such as colloidal P b S e quantum dots, polyaniline nanofibers, and reduced‐graphene‐oxide flakes, are placed in the nanogap by DEP from bottom up. The threshold electric field for the DEP placement of P b S e nanocrystals was roughly estimated to be about 8.3 × 10 4 V/cm under our experimental configuration. After the DEP process, several procedures for reducing contact resistances are attempted and measurements of intrinsic electron transport in versatile nanomaterials are performed. It is experimentally confirmed that electron transport in both P b S e nanocrystal arrays and polyaniline nanofibers agrees well with Prof. P ing S heng's model of granular metallic conduction. In addition, electron transport in reduced‐graphene‐oxide flakes follows M ott's 2D variable‐range‐hopping model. This study illustrates an integration of the electron‐beam lithography and the DEP techniques for a precise manipulation of nanomaterials into electronic circuits for characterization of intrinsic properties.
Abstract To fabricate reliable nanoelectronics, whether by top-down or bottom-up processes, it is necessary to study the electrical properties of nanocontacts. The effect of nanocontact disorder on device properties has been discussed but not quantitatively studied. Here, by carefully analyzing the temperature dependence of device electrical characteristics and by inspecting them with a microscope, we investigated the Schottky contact and Mott’s variable-range-hopping resistances connected in parallel in the nanocontact. To interpret these parallel resistances, we proposed a model of Ti/TiO x in the interface between the metal electrodes and nanowires. The hopping resistance as well as the nanocontact disorder dominated the total device resistance for high-resistance devices, especially at low temperatures. Furthermore, we introduced nanocontact disorder to modulate the light and gas responsivities of the device; unexpectedly, it multiplied the sensitivities compared with the intrinsic sensitivity of the nanowires. Our results improve the collective understanding of electrical contacts to low-dimensional semiconductor devices and will aid performance optimization in future nanoelectronics.
We present results of our investigation of the synthesis and structural properties of bismuth nanoparticles. Particles of bismuth with sizes on the order of 10-30 nm are synthesized by low-temperature, solution-chemical techniques. Chemical reduction of bismuth salts takes place in specifically-tailored, aqueous-organic microemulsions. The resulting nanoparticles are characterized by x-ray diffraction, optical absorption and electron microscopy.
Understanding the shape-dependent superlattices and resultant anisotropies of both structure and property allows for rational design of materials processing and engineering to fabricate transformative materials with useful properties for applications. This work shows the structural evolution from square lattice of two-dimensional (2D) thin film to rhombic lattice of large three-dimensional (3D) assembles of Pt3Co nanocubes (NCs). Synchrotron-based X-ray supercrystallography determines the superlattice of large 3D supercrystal into an obtuse rhombohedral (Rh) symmetry, which holds a long-range coherence of both NC translation and atomic crystallographic orientation. The Rh superlattice has a trigonal cell angle of 104°, and the constitute NCs orient their atomic Pt3Co(111) planes to the superlattice Rh[111] direction. The temperature-dependent in situ small and wide-angle X-ray scattering (SAXS/WAXS) measurements reveal a thermally induced superlattice contraction of supercrystal, which maintains translational ordering but slightly develops orientational disordering. The observed increases of both the packing density and the rotation magnitude of NCs indicate a rational compromise between configurational and rotational entropies of NCs. The resultant minimization of the total free energy is responsible for the formation and stability of the obtuse Rh superlattice. The temperature-dependent in situ measurements of SAXS and electrical resistance reveal that, in conjunction with the thermally induced sharp contraction of superlattice at 160 °C, the supercrystal becomes measurable of electrical resistance, which was followed by a temperature-dependent linear increase. Upon rapid annealing from 250 °C, the supercrystal remains almost constant in both structure and electrical resistance. The heating-enabled electrical conductivity of the supercrystal at high temperature implies the formation of a NC-interconnected architecture. The experiments and overall analysis provide solid evidence and essential information for the use of shape-dependent structural anisotropies of supercrystal to create nanobased novel architecture with desired properties.
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