Preparation and Characterization of Silver-Iron Bimetallic Nanoparticles on Activated Carbon Using Plasma in Liquid Process

The mono and bi-metallic nanoparticles have conspicuous properties and are widely used in the environment, energy, and medical fields. In this study, bimetallic nanoparticles composed of silver and iron were precipitated on the surface of activated carbon in a single process using plasma in liquid process (PLP). Silver-iron ions and various radicals were actively generated in the aqueous reactant solution by the PLP. Although metals were precipitated on AC depending on the number of precursors added to the aqueous reactant solution, the standard reduction potential of silver ions was higher than that of iron ions, so silver precipitated on AC. The silver precipitate on AC was a mixture of metallic silver and silver oxide, and iron was present as Fe3O4. Spherical nanoparticles, 100–120 nm in size, were observed on the surface of the Ag-Fe/AC composite. The composition of the bimetallic nanoparticles could be controlled by considering the ionization tendency and standard reduction potential of metal ions and controlling the concentration of the precursors. The PLP presented in this study can be applied to the preparing method of bimetallic nanoparticle/carbon materials and can be expected to be used in the prepare of energy and environmental materials such as MFC and absorption materials for removing pollutants.

Facile Preparation of Ni-Co Bimetallic Oxide/Activated Carbon Composites Using the Plasma in Liquid Process for Supercapacitor Electrode Applications

In this study, a plasma in a liquid process (PiLP) was used to facilely precipitate bimetallic nanoparticles composed of Ni and Co elements on the surface of activated carbon. The physicochemical and electrochemical properties of the fabricated composites were evaluated to examine the potential of supercapacitors as electrode materials. Nickel and cobalt ions in the aqueous reactant solution were uniformly precipitated on the AC surface as spherical nanoparticles with a size of about 100 nm by PiLP reaction. The composition of nanoparticles was determined by the molar ratio of nickel and cobalt precursors and precipitated in the form of bimetallic oxide. The electrical conductivity and specific capacitance were increased by Ni-Co bimetallic oxide nanoparticles precipitated on the AC surface. In addition, the electrochemical performance was improved by stable cycling stability and resistance reduction and showed the best performance when the molar ratios of Ni and Co precursors were the same.

Directional coupling in spatially distributed nanoreactors

Chemical front propagates through a closed-packed cluster of nanoreactors made of hollow nanoshells filled with reactant solution.

Recent Advances in Fabrication of Photocatalytic Micro-Reactor

Microfluidic technology has been increasingly applied in field of photo catalytic reactor because of the large surface to volume ratio, shorter diffusion distance of the reactant solution, higher mixing efficiency and lower cost. This article reviews the detail progress in fabrication of micro-reactor for degradation of dye in waste water. Importantly, dye degradation required uniform UV light exposure which could be resolved by carrying out degradation in a micro-reactor. This paper discussed several of potential and commercial photocatalytic micro-reactor fabrication and configurations, in particular, the polydimethyl siloxane (PDMS) photocatalytic reactors.

Morphology Control of LiMnPO4 Cathodes by a Careful Choice of Additives

ABSTRACTLiMnPO4 cathode materials of various sizes and shapes are synthesized by a hydrothermal method. In order to control the morphology of the LiMnPO4 particles, a nonionic surfactant or a cationic surfactant has employed as a key additive to the reactant solution. LiMnPO4 nanoparticles of grain-shape and rod-shape can be made with sizes between about 100 and 300 nm by adding a nonionic large polymer surfactant. Micrometer-sized LiMnPO4 particles of cuboid shape result from the reaction with a cationic surfactant. LiMnPO4 spheres of about 20 μm diameter are produced when no surfactant is added. The cathode composed of nanocrystalline (about 100 nm size) LiMnPO4 exhibited the best performance with the specific capacity of 153 mAhg-1 for the first battery cycle.

The Effect of Oxygen on Bunsen Reaction with HIX Solution in Sulfur-Iodine Hydrogen Production Process

The Sulfur-Iodine thermochemical hydrogen production process (SI process) has been focused as one of the most promising method for hydrogen production by water splitting. SI process consists of three sections as follow; (1) Bunsen reaction, (2) H2SO4 decomposition and (3) HI decomposition. The O2 produced in a H2SO4 decomposition section could be supplied directly to the Bunsen reaction section without additional separation. Meanwhile, the reactant solution supplied to a Bunsen reaction section could be supplied as the type of a HIx (I2 + HI + H2O) solution, since only the separation of I2 in a HIx solution recycled from a HI decomposition section is very difficult. Therefore, we carried out the reaction using SO2 and SO2-O2 mixture gases in presence of the HIx solution to identify the effect of O2 in the Bunsen reaction. From the results, the amount of I2 unreacted under the feed of SO2-O2 mixture gases was very small higher than those under the feed of SO2 gas only, while the amount of HI produced was relatively decreased. In addition, the amount of impurities in each phase produced from the Bunsen reaction with the HIx solution was hardly affected by the O2/SO2 molar ratios.

Tubular precipitation structures: materials synthesis under non-equilibrium conditions

Inorganic precipitation reactions are known to self-organize a variety of macroscopic structures, including hollow tubes. We discuss recent advances in this field with an emphasis on experiments similar to ‘silica gardens’. These reactions involve metal salts and sodium silicate solution. Reactions triggered from reagent-loaded microbeads can produce tubes with inner radii of down to 3 μm. Distinct wall morphologies are reported. For pump-driven injection, three qualitatively different growth regimes exist. In one of these regimes, tubes assemble around a buoyant jet of reactant solution, which allows the quantitative prediction of the tube radius. Additional topics include relaxation oscillations and the templating of tube growth with pinned gas bubble and mechanical devices. The tube materials and their nano-to-micro architectures are discussed for the cases of silica/Cu(OH) 2 and silica/Zn(OH) 2 /ZnO tubes. The latter case shows photocatalytic activity and photoluminescence.

Effect of Temperature, Pressure and Volume of Reacting Phase on Photocatalytic CO2 Reduction on Suspended Nanocrystalline TiO2

The effect of temperature, pressure and volume of reactant solution on the photocatalytic reduction of CO2 at suspended TiO2 was studied in an annular batch photoreactor. Reaction products in the liquid phase (methanol, formaldehyde) and in the gas phase (methane, ethane, carbon monoxide, molecular oxygen and hydrogen) were analysed by gas chromatography. The photocatalytic reduction of CO2 was not sensitive significantly to small temperature variations within 10 K. The CO2 pressure at carbonation of the solution influenced the selectivity of the CO2 conversion to methane and methanol, while the dihydrogen yield was higher by two orders of magnitude and independent of the pressure. The dependence of the product yields on the volume of the liquid phase confirmed the fact that the requirement for perfect mixing was difficult to fulfil for the annular configuration of the reactor.

Production of Nanostructures Under Ultraturbulent Collision Reaction Conditions - Application to Catalysts, Superconductors, CMP Abrasives, Ceramics, and Other Nanoparticles

The development, operation and applications of a novel continuous chemical reactor system are described. The system, known as a Multiple Stream Mixer/Reactor (or MMR), produces nanoparticles by direct precipitation from two or more reactant solution streams in an extreme energy density, ultraturbulent, collision reaction region. Sensors and a control system are employed to assure constant mixing conditions and desired stoichiometry in the reaction region. The interaction chamber is designed to allow macro-, meso- and micromixing during processing. This allows control of product purity, yield, size, size distribution, and phase purity. Typical nanoparticle diameters in the one to ten nanometer range are often achievable, with tight size distribution. The MMR can be scaled from development quantities to tons/hour for production applications.