Daniel R. Talham

Bio: Daniel R. Talham is an academic researcher from University of Florida. The author has contributed to research in topics: Langmuir–Blodgett film & Prussian blue. The author has an hindex of 38, co-authored 196 publications receiving 4838 citations. Previous affiliations of Daniel R. Talham include University of Nantes.

Preparation of Ag/SiO2 nanosize composites by a reverse micelle and sol-gel technique

Abstract: Spherical nanosize Ag/SiO2 composite particles have been synthesized within reverse micelles via metal alkoxide hydrolysis and condensation. The size of the particles and the thickness of the coating can be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethoxysilane (TEOS) within the microemulsion. Composite particles in the size range 20−35 nm are produced. As the molar ratio of water to surfactant is increased above 10, the size distribution broadens. Absorption spectra have been used to dynamically monitor the reaction and growth. The effects of other synthesis parameters, such as the molar ratio of water to TEOS and the amount of base catalyst, are discussed. Possible mechanisms for the formation of the nanocomposite particles are also discussed.

Bimetallic cyanide-bridged coordination polymers as lithium ion cathode materials: core@shell nanoparticles with enhanced cyclability.

Abstract: Prussian blue analogues (PBAs) have recently been proposed as electrode materials for low-cost, long-cycle-life, and high-power batteries. However, high-capacity bimetallic examples show poor cycle stability due to surface instabilities of the reduced states. The present work demonstrates that, relative to single-component materials, higher capacity and longer cycle stability are achieved when using Prussian blue analogue core@shell particle heterostructures as the cathode material for Li-ion storage. Particle heterostructures with a size dispersion centered at 210 nm composed of a high-capacity K(0.1)Cu[Fe(CN)(6)](0.7)·3.8H(2)O (CuFe-PBA) core and lower capacity but highly stable shell of K(0.1)Ni[Fe(CN)(6)](0.7)·4.1H(2)O have been prepared and characterized. The heterostructures lead to the coexistence of both high capacity and long cycle stability because the shell protects the otherwise reactive surface of the highly reduced state of the CuFe-PBA core. Furthermore, interfacial coupling to the shell suppresses a known structural phase transition in the CuFe-PBA core, providing further evidence of synergy between the core and shell. The structure and chemical state of the heterostructure during electrochemical cycling have been monitored with ex situ X-ray diffraction and X-ray absorption experiments and compared to the behavior of the individual components.

Conducting and magnetic Langmuir-Blodgett films.

Abstract: An underlying principle of molecule-based conductors is that cooperative properties depend on intermolecular interactions and, therefore, the arrangement of molecules in condensed phases. Electronic band structures are determined by the distances between molecules and their orientation relative to each other. The same basis molecule in the same oxidation state can lead to dramatically varied solidstate properties if it crystallizes in different phases involving different molecular packing configurations. This point was hammered home in the early days of studies on the organic donor bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF), 1, which, in cation-

Recent developments in the preparation and properties of nanometer-size spherical and platelet-shaped particles and composite particles

Abstract: By using self-assembly molecules as a template, nanometer-sized plate-like metal oxide and semiconductor particles can be obtained by confined growth inside the lamellar bilayers of microemulsion systems. It was found that a strong chemical affinity between the metal salt and the polar head group of amphiphilic molecules and the anisotropic structure of microemulsion systems play a premier role in the anisotropic growth. Nanometer-sized composite particles (nano-composites) with a core-shell structure have been prepared by arrested precipitation of metal or semiconductor clusters in reverse micelles, followed by hydrolysis and condensation of organometallic precursors in the microemulsion matrices. Temporally discrete nucleation and growth at elevated temperature (70 °C) give the resulting particles a narrow size distribution and defined crystallinity. Both the size of the core particles and the thickness of the coating layers can be varied by controlling processing parameters such as the ratio of water to surfactant and the ratio of water to organometallic precursors. By controlling the pH conditions and aging temperatures, a transparent gel composing the nanometer-sized inorganic clusters has been obtained. Optical properties of nanometer-sized composite particles are reviewed. For silver metal clusters and nano-composites, the shift of the absorption peak at the surface-plasmon resonance frequency due to the classical limited mean-free path of the conduction electrons or quantum size effects has been observed. The enhanced third-order non-linear susceptibility of the silver nano-composites results from the local-field enhancement and size effects, which has been experimentally demonstrated by the optical phase-conjugation technique.

Persistent photoinduced magnetism in heterostructures of prussian blue analogues.

Abstract: Heterostructured ABA thin films consisting of two different Prussian blue analogues, where A is a ferromagnet and B is a photoinducible ferrimagnet, have been fabricated for the first time. This novel arrangement allows the magnetization to be decreased by irradiation with white light and significantly increases the ordering temperature of the photoinduced magnetism from 18 to 75 K.

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

Abstract: Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Nanoparticles as Recyclable Catalysts: The Frontier between Homogeneous and Heterogeneous Catalysis

Abstract: Interest in catalysis by metal nanoparticles (NPs) is increasing dramatically, as reflected by the large number of publications in the last five years. This field, "semi-heterogeneous catalysis", is at the frontier between homogeneous and heterogeneous catalysis, and progress has been made in the efficiency and selectivity of reactions and recovery and recyclability of the catalytic materials. Usually NP catalysts are prepared from a metal salt, a reducing agent, and a stabilizer and are supported on an oxide, charcoal, or a zeolite. Besides the polymers and oxides that used to be employed as standard, innovative stabilizers, media, and supports have appeared, such as dendrimers, specific ligands, ionic liquids, surfactants, membranes, carbon nanotubes, and a variety of oxides. Ligand-free procedures have provided remarkable results with extremely low metal loading. The Review presents the recent developments and the use of NP catalysis in organic synthesis, for example, in hydrogenation and C--C coupling reactions, and the heterogeneous oxidation of CO on gold NPs.

Molecular self-assembly and nanochemistry: A chemical strategy for the synthesis of nanostructures

Abstract: Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

Metal–organic frameworks and their derived nanostructures for electrochemical energy storage and conversion

Abstract: Metal–organic frameworks (MOFs) have received a lot of attention because of their diverse structures, tunable properties and multiple applications such as gas storage, catalysis and magnetism. Recently, there has been a rapidly growing interest in developing MOF-based materials for electrochemical energy storage. MOFs have proved to be particularly suitable for electrochemical applications because of their tunable chemical composition that can be designed at the molecular level and their highly porous framework in which fast mass transportation of the related species is favorable. In this review, the recent progress in fabricating MOFs and MOF-derived nanostructures for electrochemical applications is presented. The review starts with an introduction of the principles and strategies for designing targeted MOFs followed by a discussion of some novel MOF-derived structures and their potential applications in electrochemical energy storage and conversion. Finally, major challenges in electrochemical energy storage are highlighted and prospective solutions from current progress in MOF-based nanostructure research are given.