Synthesis of low-cost multi-element Pt-based alloy nanoparticles as catalysts for the oxygen reduction reaction.

Due to their high catalytic activity, stability, and economic benefits, Pt-based multi-element alloyed nanoparticles (NPs) are considered promising electrodes for oxygen reduction reactions. However, a synthesis method capable of controlling the reduction reaction of elements with different redox potentials to synthesize multimetallic alloy NPs is yet to be developed. In this study, monodisperse NiPtPd alloy NPs with varying compositions were synthesized using 1-heptanol as a reducing solvent. The selection of low-reducing noble metal precursors and complexing agents is done strategically to adjust the reduction time of metal ions. The spectroscopic results confirmed that olelylamine (OAm) preferentially coordinates with Pt ions, while trioctylphosphine (TOP) preferentially coordinates with Pd ions. Consequently, control of the elemental distribution within the particle is successfully achieved by adjusting the OAm/Pt and TOP/Pd molar ratios. Subsequently, Ni78Pt11Pd11 alloy NPs were designed, and their catalytic properties as electrodes in the oxygen reduction reaction (ORR) were examined. Despite a low noble metal content of 22%, the catalytic performance and stability were superior to and comparable to those of commercial Pt NPs, respectively.

Effects of soybean curd residue and rice bran on lamb performance, health, and meat quality.

Recycling food by-products as animal feed could decrease livestock production costs. We investigated how replacing conventional corn and wheat bran feed (control) with rice bran and soybean curd residue (RBSR) would influence lamb performance and meat quality. Eleven lambs were divided into the control and the RBSR-fed groups. The amount of feed consumed by the lambs, as well as their body weight, nutrient properties (total protein, non-esterified fatty acid, total cholesterol, glucose concentrations) in blood samples, and fecal condition were evaluated. Meat quality (water holding capacity, cooking loss, fat content, and shear force) of their carcasses were also evaluated. Results shows daily body weight gain per lamb in the RBSR-fed group was approximately 2.2-fold than that in the control group. The mean total blood protein and glucose concentrations exhibited increasing trends after feeding with RBSR. In addition, the shear force of the meat was significantly lower and crude fat content was significantly higher in RBSR-fed lambs than in lamb fed the control feed. The study concluded that, RBSR could replace conventional feed for Japanese sheep and can be used to not only reduce feed and disposal costs but also increase animal production and meat quality.

Precursor-templated synthesis of thermodynamically unfavored platinum nanoplates for the oxygen reduction reaction.

Controlling the shape of Pt-based nanomaterials is a major strategy to enhance the electrocatalytic performance towards the oxygen reduction reaction (ORR). Since the Pt (111) facet exhibits desirable electrochemical properties, Pt nanoplates enclosed by {111} facets are promising candidates. However, plate-shaped Pt crystals have thermodynamically unfavored structures, making syntheses challenging. Here we report a novel precursor-templated route to synthesize Pt nanoplates. Specifically, precipitated (NH4)2PtCl6 prepared in aqueous solution is used as the Pt precursor followed by the addition of NaBH4 as a reducing agent. With domain matching epitaxy, Pt nanoplates grow on the surface of the precipitated precursor, selectively exposing the {111} facets. Compared to those of commercial Pt/C at 0.90 and 0.85 V, the ORR properties of Pt nanoplates display a 1.5- and 5.2-fold enhancement in the mass activity, and a 3.3- and 11.6-fold enhancement in the specific activity, respectively. The superior ORR activities and the unique shape of Pt nanoplates are maintained for at least 5000 potential cycles.

Environmentally friendly synthesis and formation mechanism of copper nanowires with controlled aspect ratios from aqueous solution with ascorbic acid.

Copper (Cu) nanowires (NWs) were synthesized by the reduction of Cu-chloride complexes using ascorbic acid (AA) as a mild reducing agent, polyvinylpyrrolidone (PVP) as a capping agent, and NaCl as an additive under atmospheric conditions at 80 °C. Surface analyses revealed that both Cl ions and PVP were required for the synthesis of Cu NWs. Together, the Cl ions and PVP capped the Cu (1 0 0) side faces, leading to anisotropic growth of Cu NWs along the [1 1 0] direction. To obtain Cu NWs with high aspect ratios, we evaluated the synthetic mechanism under different reaction conditions. The results indicated that the presence of dissolved oxygen (DO) was the dominant factor affecting aspect ratio of Cu NWs. DO and hydrogen peroxide resulting from the reaction between DO and AA oxidized the surfaces of the growing Cu NWs, preventing further growth. Decreasing the amount of oxides on the Cu NW surfaces and removing DO increased the aspect ratios of the Cu NWs. The results indicated that DO should be removed from the reaction solution to obtain high-aspect-ratio Cu NWs in aqueous solutions containing AA.

Design of monoalcohol - Copolymer system for high quality silver nanowires.

Research to improve the dimensional properties of silver nanowires (Ag NWs) for transparent conductive film (TCF) applications are being carried out intensively. However, the protocol for the designed synthesis of high-quality Ag NWs is yet to be developed due to the inadequacy of knowledge on the role of parameters. Here, we attempt to elucidate the role played by the parameters and propose a monoalcohol-copolymer based system for the designed synthesis of Ag NWs superior in quality to the one synthesized using conventional ethylene glycol (EG)-polyvinylpyrrolidone (PVP) system. The key findings of the study are as follows: (1) the solubility of Ag source and the partially formed AgCl particles in monoalcohols was found to play an important role not only in the reduction to metallic Ag but also on the uniaxial growth, (2) the adsorption of capping agents on Ag NWs was carried through O and N atoms in the base molecule and their binding energies indicated that the strength is the key parameter to obtain Ag NWs with high aspect ratio, (3) the properties of nanowire could be enhanced through copolymerization of VP and base molecules that have O- and N-based ligands, and (4) the influence of copolymerization on the physical and chemical properties of the surface active agent has been theoretically and experimentally verified. Consequently, we succeeded in the development of a new technique to synthesize high yield of Ag NWs with improved aspect ratio than EG-PVP system by using benzyl alcohol as reducing solvent and N-vinylpyrrolidone/N,N-diethylaminoethyl metacrylate copolymer as a capping agent. The optical transmittance and electrical resistivity of TCFs prepared using the Ag NWs with an average diameter of 43 nm, and an average length of 13 µm were 98.6% and R: 49.1 Ω/□, respectively.

Aqueous Phase Synthesis of CuIn Alloy Nanoparticles and Their Application for a CIS (CuInSe2)-Based Printable Solar Battery.

To apply CuInSe2 (CIS)-based printable solar batteries; an aqueous phase synthesis method of Cu-In (CI) alloy nanoparticles is studied. Metal complexes in the original solution are restricted to homogenized species by utilizing calculations. For example; [(Cu2+)(ASP2-)2] [ASP: the "body (C4H5O4N)" of aspartic acid (C4H7O4N)] is predominant in the pH 6-13 region (CASP/CCu > 6); while In complexes can be restricted to [(In3+)(OH-)(EDTA4-)] (pH 10-12; CEDTA/CIn = 2) and/or [(In3+)(ASP2-)2] (pH 7-9; CASP/CIn = 5). These results indicate that the added amount of complex reagents should be determined by calculations and not the stoichiometric ratio. The reduction potential of homogenized metal complex is measured by cyclic voltammetry (CV) measurements and evaluated by Nernst's equation using the overall stability constants. CuIn alloy nanoparticles with a small amount of byproduct (In nanoparticles) are successfully synthesized. The CI precursor films are spin-coated onto the substrate using a 2-propanol dispersion. Then the films are converted into CIS solar cells; which show a maximum conversion efficiency of 2.30%. The relationship between the open circuit potential; short circuit current density; and fill factor indicate that smoothing of the CIS films and improving the crystallinity and thickness increase the solar cell conversion efficiency.

Synthesis of ligand-stabilized metal oxide nanocrystals and epitaxial core/shell nanocrystals via a lower-temperature esterification process.

The properties of metal oxide nanocrystals can be tuned by incorporating mixtures of matrix metal elements, adding metal ion dopants, or constructing core/shell structures. However, high-temperature conditions required to synthesize these nanocrystals make it difficult to achieve the desired compositions, doping levels, and structural control. We present a lower temperature synthesis of ligand-stabilized metal oxide nanocrystals that produces crystalline, monodisperse nanocrystals at temperatures well below the thermal decomposition point of the precursors. Slow injection (0.2 mL/min) of an oleic acid solution of the metal oleate complex into an oleyl alcohol solvent at 230 °C results in a rapid esterification reaction and the production of metal oxide nanocrystals. The approach produces high yields of crystalline, monodisperse metal oxide nanoparticles containing manganese, iron, cobalt, zinc, and indium within 20 min. Synthesis of tin-doped indium oxide (ITO) can be accomplished with good control of the tin doping levels. Finally, the method makes it possible to perform epitaxial growth of shells onto nanocrystal cores to produce core/shell nanocrystals.