Hydrogen Vanadate as an Effective Stabilizer of Pd Nanocatalysts for Formic Acid Electroxidation

In this paper, a simple chemical reduction route is discussed that results in small size, uniform dispersion of Pd nanoparticles supported on carbon black. HVO42-, the tridentate oxoanion with its O-O distance of 2.76 angstrom, closely matching with the Pd-Pd distance (2.75 angstrom), is expected to be an effective stabilizer for Pd according to the lattice size-matching binding model (Finke, R. G.; Ozkar, S. Coord. Chem. Rev. 2004, 248, 135). Because it has never been tested, HVO42- is exploited and found to be a very simple and effective stabilizer.

Rare Earth Pyrophosphates: Effective Catalysts for the Production of Acrolein from Vapor-phase Dehydration of Glycerol

Vapor-phase dehydration of glycerol to produce acrolein was investigated at 320 A degrees C over rare earth (including La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu) pyrophosphates, which were prepared by precipitation method. The most promising catalysts were characterized by means of XRD, FT-IR, TG-DTA, BET and NH3-TPD measurements. The excellent catalytic performance of rare earth pyrophosphate depends on the appropriate surface acidity which can be obtained by the control of pH value in the precipitation and the calcination temperature, e.g. Nd-4(P2O7)(3) precipitated at pH = 6 and calcined at 500 A degrees C in the catalyst preparation.

A high-performance tandem white organic light-emitting diode combining highly effective white-units and their interconnection layer

By utilizing 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline:Li/MoO3 as an effective charge generation layer (CGL), we extend our recently demonstrated single-emitting-layer white organic light-emitting diode (WOLED) to realize an extremely high-efficiency tandem WOLED. This stacked device achieves maximum forward viewing current efficiency of 110.9 cd/A and external quantum efficiency of 43.3% at 1 mu A/cm(2) and emits stable white light with Commission Internationale de L'Eclairage coordinates of (0.34, 0.41) at 16 V. It is noted that the combination of effective single units and CGL is key prerequisite for realizing high-performance tandem WOLEDs.

Lead(IV) dioxide: an effective electron injection material to realize high-efficiency inverted top-emitting organic light-emitting diodes

Lead(IV) dioxide (PbO2) has been used as the electron injection layer (EIL) to realize high-efficiency inverted top-emitting organic light-emitting diodes (I-TOLEDs). It can be seen that the inserting of the PbO2 EIL significantly reduces operational voltage, thus greatly improving the current efficiency and power efficiency of fabricated I-TOLEDs. The 10-(2-benzothiazolyl)-1, 1, 7, 7-tetramethyl-2, 3, 6, 7-tetrahydro-1H, 5H, 11H-[1] benzopyrano [6, 7, 8-ij] quinolizin-11-one (C545T)-based I-TOLEDs with the PbO2 EIL exhibit a maximum current efficiency of 31.6 cd A(-1) and a maximum power efficiency of 14.3 lm W-1, which are both higher than 22.5 cd A(-1) and 5.4 lm W-1 of the I-TOLEDs with LiF as the EIL respectively. A detailed analysis with respect to the role mechanism of PbO2 in electron injection has been presented. The improvement in EL performance is attributed to the formation of the interfacial dipoles at the electrode interface due to charge transfer between PbO2 and Alq(3).

Effective enhancement of peroxydisulfate electrochemiluminescence on C-60/DDAB films

Effective enhancement of electrochermluminescence (ECL) of peroxydisulfate on a C-60/didodecyldimethyl ammonium bromide (C-60/DDAB) film coated glassy carbon electrode (GCE) surface is reported in this paper. The C60/DDAB film gave lower cathodic current in the presence of peroxydisulfate than that from a bare GCE. To our surprise, electrochemiluminescent intensity from peroxydisulfate reduction was effectively enhanced on the C60/DDAB film, which was 50 times and 250 times higher than those from a DDAB film coated and bare GCE, respectively. Moreover, the ECL onset potential on the C60/DDAB film was about -0.9 V, which positively shifted 200 mV compared with that from the bare GCE. Dissolved oxygen and the applied potential also affected the electrochemiluminescent intensity. The presence of oxygen decreased the intensity, and the intensity reached maximum at the applied potential of -1.7 V. The unique property will greatly enrich ECL studies and applications based on fullerenes.

An effective hydrothermal route for the synthesis of multiple PDDA-protected noble-metal nanostructures

In this Article, we demonstrate an effective hydrothermal route for the synthesis of multiple PDDA-protected (PDDA = poly(diallyl dimethylammonium) chloride) noble-metal (including silver, platinum, palladium, and gold) nanostructures in the absence of any seeds and surfactants, in which PDDA, an ordinary and water-soluble polyelectrolyte, acts as both a reducing and a stabilizing agent. Under optimal experimental conditions, Ag nanocubes, Pt and Pd nanopolyhedrons, and Au nanoplates can be obtained, which were characterized by transmission electron microscopy, scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. More importantly, the nanostrucfures synthesized show potential applications in surface-enhanced Raman scattering and electrocatalysis, in which Ag nanocubes and Pt nanopolyhedrons were chosen as the examples, respectively.

A novel hybrid based on carbon nanotubes and heteropolyanions as effective catalyst for hydrogen evolution

Heteropolyanions of tungstophosphoric acid (PWA) have been successfully hybridized with carbon nanotubes (CNTs) by a severe mechanical milling. The obtained hybrid is electroactive for hydrogen evolution (HE) at potentials as positive as -0.16 V vs. Ag/AgCl in 0.2 M HClO4 aqueous solution and its electrocatalysis is up to the level of Pt/CNTs (20 wt% Pt) for HE, indicating a vigorous alternative to Pt group metals. The HE mechanism of the hybrid was also studied and it was found that the tungsten oxycarbides are the electroactive components for HE.

A simple and effective route for the preparation of poly(vinylalcohol) (PVA) nanofibers containing gold nanoparticles by electrospinning method

Poly(vinyl alcohol) (PVA) nanofibers containing gold nanoparticles have been simply obtained by electrospinning a solution containing gold nanoparticles without the additional step of introducing other stabilizing agents. The optical property of gold nanoparticles in PVA aqueous solution was observed by UV-visible absorption spectra. Morphology of the Au/PVA nanofibers and distribution of the gold nanoparticles were characterized by transmission electron. microscopy (TEM). The structure transformation was characterized from PVA to PVA/Au composite by Fourier transform infrared spectroscopy (FTIR).

An effective approach to synthesis of poly(methyl methacrylate)/silica nanocomposites

A novel synthetic route for nearly monodispersed poly(methyl methacrylate)/SiO2 composite particles (PMSCP) is reported. Silica nanoparticles modified with oleic acid were used as 'seeds'. Methyl methacrylate (MMA) monomer was copolymerized with oleic acid via in situ emulsion polymerization, in the presence of an initiator; it resulted finally in the formation of composites with core-shell morphology. The composite particles were examined by transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The number of silica particles inside the composite particles increases with an increase in the silica concentration. The effect of grafted silica concentration on the morphology of PMSCP is also reported in detail. It was found by thermogravimetric analysis that PMSCP show a potential application for fire retardance.

An effective layer-by-layer adsorption and polymerization method to the fabrication of polyoxometalate-polypyrrole nanoparticle ultrathin films

A layer-by-layer (LbL) adsorption and polymerization method was developed for the controllable preparation of polypyrrole (PPy) nanoparticles within ultrathin films. By repetitive adsorption of pyrrole and subsequent polymerization with 12-molybdophosphoric acid, the polyelectrolyte multilayer films containing PPy nanoparticles were fabricated. UV-visible absorption spectrocopy, Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM), transmission electron microscopy (TEM) and cyclic voltammograras (CVs) were used to characterize the PPy nanoparticles and their multilayer thin films. UV-visible spectra indicate that the growth of PPy nanoparticles was regular and occurred within the polyelectrolyte films. The size of prepared PPy nanoparticles was found by TEM to increase with the increasing of polymerization cycles. The electrochemistry behavior of the multilayer thin films was studied in detail on ITO. The results suggest that the LbL adsorption and polymerization method developed herein provides an effective way to prepare PPy nanoparticles in the polymer matrix.

Effective energy transfer and luminescence of LB films based on europium-substituted heteropolytungstate

The europium-substituted heteropolytungstate K13Eu(SiW11O39)(2) was successfully assembled into two lipids by LB technique for the first time. X-ray diffraction has shown a well defined lamellar for the LB films. The LB films have been characterized by fluorescence spectra and the characteristic luminescence behaviors were discussed. The ligand-metal charge transfer band could be observed in the spectra of the LB films, which could not be found in that of heteropolytungstate solid. The results of fluorescence spectra indicate the energy could be effectively transferred from ligands to the Eu3+ ions in the LB films and the luminescence efficiency was increased greatly. The influences of various lipids on the luminescence of polyoxometalates were investigated. The various interactions between monolayer and polyanions have different effect on the luminescence properties of europium-substituted heteropolytungstate.

Effect of PMR-POI on the melt behavior and isothermal crystallization of poly(phenylene sulfide)

The crystallization behavior of neat PPS and PPS in blends with PMR-POI prepared by melt mixing were investigated by differential scanning calorimetry (DSC). It was found that POI was an effective nucleation agent of the crystallization for PPS. The enthalpy of crystallization of PPS in the blends increased compared with that of neat PPS. During isothermal crystallization from melt, the dependence of relative degree of crystallinity on time was described by the Avrami equation. It has been shown that the addition of POI causes an increase in the overall crystallization rate of PPS; it also changed the mechanism of nucleation of the PHB crystals from homogeneous nucleation to heterogeneous nucleation. The equilibrium melting temperature of PPS and PPS/POI blends were determined. The analysis of kinetic data according to nucleation theories shows that the increase in crystallization rate of PPS in the composite is due to the decrease in surface energy of the extremity surface.

Effective descriptions of molecular structures and the quantitative structure - Activity relationship studies

In this research. we found CoMFA alone could not obtain sufficiently a strong equation to allow confident prediction for aminobenzenes. When some other parameter. such as heat of molecular formation of the compounds, was introduced into the CoMFA model, the results Were improved greatly. It gives us a hint that a better description for molecular structures will yield a better prediction model, and this hint challenged us to look for another method-the projection areas of molecules in 3D space for 3D-QSAR. It is surprising that much better results than that obtained by using CoMFA Were achieved. Besides the CoMFA analysis. multiregression analysis and neural network methods for building the models were used in this paper.