Highly catalytic activity of platinum-gold particles modified poly(p-aminophenol) electrode for oxygen reduction reaction

Journal of Solid State Electrochemistry - A highly active electrocatalyst has been developed based on poly(p-aminophenol) polymer film modified with Pt-Au bimetallic particles on a glassy carbon...     

Photoinduced reduction of catalytically and biologically active Ru(II)bisterpyridine-cytochrome c bioconjugates

Ruthenium(II)bisterpyridine chromophores were covalently linked to iso-1 cytochrome c from yeast to create light-activated donor-acceptor bioconjugates.     

Radiation synthesis of copper sulphide/poly(vinyl alcohol) nanocomposites films: an efficient and reusable catalyst for p-nitrophenol reduction

ABSTRACT

Copper sulphide nanoparticles (CuS NPs) were in situ synthesised via irradiation process, using Poly (vinyl alcohol) (PVA) as host polymeric matrices. The as-prepared CuS/PVA nanocomposite films were characterised by X-ray diffraction (XRD) spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Both UV-VIS spectra and X-ray diffraction patterns confirmed the formation of CuS nanoparticles. The FTIR spectrum indicates the coordination between CuS nanoparticles and the OH groups of the PVA chains. The TEM image showed that the obtained CuS nanoparticles have spherical shape, monodispersed and uniform particle size distribution. The CuS/PVA nanocomposite film was successfully applied in the reduction of p-nitrophenol into p-aminophenol as a catalyst using NaBH₄ as reducing agent. The catalytic test indicates that CuS/PVA nanocomposite film has high activity for the conversion of P-NP into P-AP and effectively recycled and reused for several times.     

Highly active iridium(I) complexes for the selective hydrogenation of carbon-carbon multiple bonds

New iridium(I) complexes, bearing a bulky NHC/phosphine ligand combination, have been established as extremely efficient hydrogenation catalysts that can be used at low catalyst loadings, and are compatible with functional groups which are often sensitive to more routinely employed hydrogenation methods.     

Highly selective reduction of nitroarenes by iron(0) nanoparticles in water

Highly selective reduction of nitroarenes has been achieved using iron metal nanoparticles in water at room temperature. A wide spectrum of reducible functionalities remained inert under the reaction conditions. During the reaction a change in shape of Fe nanoparticles was observed.     

Polyporous C@WC_(1-x) composite and its electrocatalytic activity for p-nitrophenol reduction

The polyporous carbon supported tungsten carbide(polyporous C@WC_1-x) composite was prepared using hexagonal silica MCM-41 as the hard template by raw material solution impregnation,mechanical milling and simultaneous reduction and carbonization by temperature programming in mixture gas（CH₄/H₂）.The structure and morphology of polyporous C@WC_1-x composite were studied via X-ray diffraction,transmission electron microscopy and so on.The electrocatalytic property was tested for the electroreduction of p-nitrophenol（PNP） in neutral media.Results revealed that the composite is consisted of polyporous carbon and nanocrystalline WC_1-x,possessing good electrocatalytic activity in the reaction of PNP reduction.     

Synthesis of magnetic noble metal (nano)particles

Noble metal particles can be made strongly ferromagnetic or diamagnetic provided that they are synthesized in a sufficiently strong magnetic field. Here we outline two synthesis methods that are fast, reproducible, and allow broad control over particle sizes ranging from nanometers to millimeters. From magnetometry and light spectroscopy, it appears that the cause of this anomalous magnetism is the surface anisotropy in the noble metal particles induced by the applied magnetic field. This work offers an elegant alternative to composite materials of noble metals and magnetic impurities.     

Coating noble metal nanocrystals (Ag, Au, Pd, and Pt) on polystyrene spheres via ultrasound irradiation

The method of ultrasound irradiation is used for anchoring metallic nanocrystals (Ag, Au, Pd, and Pt) onto the surface of polystyrene spheres. In former studies, almost all the sonochemically prepared, coated metallic nanomaterials were formed as amorphous nanoparticles (Pol, V. G.; et al. Langmuir 2002, 18, 3352; Pol, V. G.; et al. Chem. Mater. 2003, 15, 1111; Zhong, Z. Y.; et al. Chem. Mater. 1999, 11 (9), 2350; Pol, V. G.; et al. Chem. Mater. 2003, 15, 1378), which were coated on various substrates (silica spheres, carbon spherules, titania, and alumina). On the other hand, the noble metal nanoparticles deposited on polystyrene spheres via ultrasound irradiation yielded nanocrystalline Ag, Au, Pd, and Pt particles on the surface of polystyrene as as-synthesized materials. The sonochemical mechanism is proposed based on chemical interactions between the particles.     

Highly selective reduction of nitrobenzenes to azoxybenzenes with a copper catalyst

A convenient protocol for highly selective delivery of azoxybenzenes from reduction of nitrobenzenes was developed by utilizing a copper catalyst. A variety of functional groups and substitution were well tolerated.     

Correlation between the electrification and molecular mobility of noble metal nanocomposites based on arabinogalactan

Spin-spin relaxation of arabinogalactan and its composites with gold and silver nanoparticles in aqueous solutions was studied from the viewpoint of the possible effect of electrification on the mobility of arabinogalactan macromolecules.     

Ultrasound-assisted rapid reduction of nitroaromatics to anilines using gallium metal

Abstract

The reduction of nitroaromatic compounds to anilines is widely used throughout organic synthesis. Typical methods of performing this transformation utilize hydrogenation over a pyrophoric catalyst or a finely divided reducing metal, which often affords heterogeneous mixtures that are difficult to purify. Herein, we report for the first time the use of gallium metal as a reducing agent in organic synthesis. The reaction proceeds under aerobic conditions and affords homogeneous mixtures for a convenient workup. Using this method, twelve anilines were obtained in 33% to quantitative yields with short reaction times of 10-60?minutes.     

Highly selective thioalcohol modified phthalocyanine sensors for Ag(I) and Pd(II) based on target induced J- and H-type aggregations: synthesis, electrochemistry and peripheral metal ion binding studies

We have described highly selective 1(4),8(11),15(18),22(25)-(1-hydroxyhexan-3-ylthio)-phthalocyanine sensors, M{Pc[α-SCH(C(3)H(7))(C(2)H(5)OH)](4)} (MPc(α-HHT)(4), where M = Zn(II) (2), Cu(II) (3) or Co(II) (4) and HHT: -SCH(C(3)H(7))(C(2)H(5)OH)). The formation of S-M-S {S = sulfur; M = Ag(I) or Pd(II)} bonds on the periphery in the case of Ag(I) and Pd(II) metal ions induces H- or J-aggregation, respectively, which results in significant changes in the absorption of the B- and, in particular, the Q-band. The binding ratios of Ag(I) to the periphery of 2 and 3 were found to be ca. 2:1 and 3:2, respectively. On the other hand, the binding ratios of Pd(II) to the periphery of the same compounds were found to be 3:1 and 4:1. The fluorescence of 2 exhibited distinct changes in response to treatment with Ag(I) and Pd(II) ions in solution. The fluorescence spectra emission intensity of 2 was quenched upon titration with Ag(I) and Pd(II) and a new emission maximum was observed upon titration with Pd(II). FTIR, (1)H-NMR, (13)C-NMR, UV-vis, MALDI-TOF MS and elemental analysis data were used to characterize the novel compounds. Transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FE-SEM) were also used as complementary techniques to investigate the morphology and to image the interfacial aggregates of 2. The redox behaviours of the complexes were examined by voltammetry and in situ spectroelectrochemistry on Pt in a nonaqueous medium.     

Adsorption behavior of noble metal ions (Au, Ag, Pd) on nanometer-size titanium dioxide with ICP-AES.

The adsorption behavior of gold (Au), silver (Ag) and palladium (Pd) on nanometer-size titanium dioxide (NSTD) at low concentrations was studied using inductively coupled plasma atomic emission spectrometry (ICP-AES). A preconcentration procedure of the analytes was carried out using NSTD as a solid-phase extractant before their determination by ICP-AES. The optimum conditions for adsorption were studied in detail, and under the condition that Au, Ag and Pd ions could be adsorbed and recovered quantitatively. The static adsorption capacities of Au, Ag and Pd on NSTD were 22.63, 14.06 and 11.82 mg/g, respectively. For the elution of gold, silver and palladium, a mixture of 5% thiourea solution and 3 mol L(-1) HNO3 was used. The parameters tested included: pH conditions, contact time of the analytes with NSTD, flow rate, adsorption capacity and sorption kinetics. According to the definition of IUPAC, the detection limits (3sigma) of this method for Au, Ag and Pd with an enrichment factor of 50 were (0.016), (0.006) and (0.012) microg mL(-1), respectively, the relative standard deviations (RSD) were 8.7%, 4.5% and 7.4%, respectively (n = 6). Some geological samples were determined with satisfactory results.     

Highly active nanoscale zero-valent iron (nZVI)-Fe3O4 nanocomposites for the removal of chromium(VI) from aqueous solutions

For the first time, nanoscale zero-valent iron (nZVI)-Fe(3)O(4) nanocomposites, prepared by an in situ reduction method, are employed for chromium(VI) removal in aqueous environment. 96.4% Cr(VI) could be removed by these novel materials within 2h under pH of 8.0 and initial Cr concentration of 20 mg L(-1), compared with 48.8% by bare nFe(3)O(4) and 18.8% by bare nZVI. Effects of several factors, including mass composition of nZVI-Fe(3)O(4) nanocomposites, initial pH and Cr(VI) concentration, were evaluated. The optimal ratio of nFe(3)O(4) to nZVI mass lies at 12:1 with a fixed nZVI concentration of 0.05 g L(-1). Low pH and initial Cr(VI) concentration could increase both the Cr(VI) removal efficiency and reaction rate. Corresponding reaction kinetics fitted well with the pseudo second-order adsorption model. Free energy change (ΔG) of this reaction was calculated to be -4.6 kJ mol(-1) by thermodynamic study, which confirmed its spontaneous and endothermic characteristic. The experimental data could be well described by the Langmuir and Freundlich model, and the maximum capacity (q(max)) obtained from the Langmuir model was 100 and 29.43 mg g(-1) at pH 3.0 and 8.0, respectively. The reaction mechanism was discussed in terms of the mutual benefit brought by the electron transfer from Fe(0) to Fe(3)O(4).     

A noble interaction: An assessment of noble gas binding ability of metal oxides (metal = Cu,Ag, Au)

An in silico study is performed on the structure and the stability of noble gas (Ng) bound MO complexes (M = Cu, Ag, Au). To understand the stability of these Ng bound complexes, dissociation energies, dissociation enthalpy, and dissociation free energy change are computed. The stability of NgMO is also compared with that of the experimentally detected NgMX (X= F, Cl, Br). It is found that MO has lower Ng binding ability than that of MX. All the dissociation processes producing Ng and MO are endothermic in nature and for the Kr‐Rn bound MO (M = Cu, Au), and Xe and Rn bound AgO cases, the corresponding dissociation processes are turned out to be endergonic in nature at standard state. The Wiberg bond indices of Ng? M bonds and Ng→M electron transfer gradually increase from Ar to Rn and for the same Ng they follow the order of NgAuO > NgCuO > NgAgO. Energy decomposition analysis shows that the Ng? M bonds in NgMO are partly covalent and partly electrostatic in nature. Electron density analysis further highlights the partial covalent character in Ng? M bonds. © 2016 Wiley Periodicals, Inc.     

Highly selective reduction of acyclic beta-alkoxy ketones to protected syn-1,3-diols

[reaction: see text] The conversion of 1-(2-methoxyethoxy)ethyl-protected beta-hydroxy ketones to syn-1,3-ethylidene acetals is effected by Et(3)SiH and SnCl(4). This reaction is proposed to proceed via a cyclic oxocarbenium ion intermediate and provides the products in yields that range from 69 to 94% and with diastereoselectivities that are >200:1.     

Preparation and characterization of noble metal nanocolloids by silk fibroin in situ reduction

Silk fibroin (SF) is a natural protein from silkworm. It represents Chinas resplendent civili-zation as dress materials in the past 5000 a. To this day, the silk output in China is about 90000 tons per year, which is about 70% of the world overall output. In the past decade, it has been found that silk fibroin has special properties for being used as healthy foods, cosmetics, enzyme immobilizing materials, cell culture medium, biosensor, artificial skin, artificial muscle, perme-able membran…     

Highly stable and selective Ru/NiFe_2O_4 catalysts for transfer hydrogenation of biomass-derived furfural to 2-methylfuran

Spinel ferrites NiFe_2O_4 supported Ru catalysts have been prepared via a simple sol–gel route and applied for converting biomass-derived furfural to 2-methylfuran. The as-prepared catalysts were characterized by thermogravimetric analysis(TG), N_2 adsorption–desorption, X-ray diffraction(XRD), scanning electronic microscopy(SEM), and X-ray photoelectron spectroscopy(XPS). Results showed that the catalysts had well-dispersed Ru active sites and large surface area for calcination temperature ranging from 300 to 500 ℃. The conversion of biomass-derived furfural into 2-methylfuran was conducted over Ru/NiFe_2O_4 through catalytic transfer hydrogenation in liquid-phase with 2-propanol as the hydrogen source. A significantly enhanced activity and increased 2-methylfuran yield have been achieved in this study. Under mild conditions(180 ℃ and 2.1 MPa N_2), the conversion of furfural exceeds 97% and 2-methylfuran yield was up to 83% over the catalyst containing 8 wt% Ru. After five repeated uses, the catalytic activity and the corresponding product yield remained almost unchanged. The excellent catalytic activity and recycling performance provide a broad prospects for various practical applications.