Advanced Materials Research Vol. 704

Abstract: Gold-palladium nanoparticles (AuPd NPs) were prepared on a layer of graphene (GR) film by potentiostatic electrodeposition from a mixture electrolyte of HAuCl₄ and H₂PdCl₄ to fabricate the AuPd NPs/graphene/glass carbon electrode (AuPd/GR/GCE). The synthesized composite has been characterized using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). Electrocatalytic oxidation of hydrazine on the surface of modified electrode was investigated with cyclic voltammetry and chronoamperometry methods, the results showed that the AuPd NPs high catalysis for the electrochemical oxidation of hydrazine and the excellent conductivity of graphene. Electrocatalytic activity of the modified electrode was investigated for the oxidation of hydrazine in 0.1 M phosphate buffer solutions (pH=6.0). Under the optimized conditions, the oxidation current of hydrazine was linear to its concentration in the range of 2185 μM, and the estimated detection limit was 0.2 μM (S/N =3).

Abstract: A simple amperometric biosensor for the analytical detection of hydrogen peroxide was developed. The biosensor was prepared by the immobilization of glucose oxidase (GOD) in the nanostructure matrix constructed through electrochemical deposition of Au nanoparticles (AuNPs) upon 2, 3-dimercaptosuccinic acid (DMSA) SAMs formed on Au electrode. The fabricated biosensor had a fast response of H₂O₂ (<10 s), and an excellent linear range of concentration from 2×10⁶ to 3.5×10³ M with a low detection limit of 0.65 μM (S/N = 3) under the optimum conditions. The Michaelis-Menten constant of the immobilized GOD was 2.0 mM, displaying a high affinity of the GOD toward H₂O₂ without loss of enzymatic activity in nanosubstrate.

Abstract: A robust and effective nanocomposite film modified gold electrode based on 2, 3-dimercaptosuccinic acid (DMSA) and Au nanoparticles (AuNPs) was prepared by a method combining self-assembly with underpotential deposition. Direct electron transfer can easily take place between a gold electrode and catalase molecules anchored on AuNPs films. Besides, the CAT/AuNPs/DMSA multilayer film had a relatively rapid and satisfactory response toward H₂O₂ with a wide linear range from 3.0×10⁶ to 5.86×10³ M and a low detection limit of 3.0 μM (S/N = 3). The Michaelis-Menten constant of the immobilized CAT was calculated to be 2.2 mM. The simple CAT/AuNPs/DMSA/Au system can be developed into a H₂O₂ biosensor.

Abstract: The Palladium-copper nanoparticles (PdCu NPs) have been prepared by potentiostatic electrodeposition from a mixture electrolyte of H₂PdCl₄ and CuSO₄,then placed the electrode in sulfuric acid using cyclic voltammetry sweep a few laps to fabricate the PdCu NPs/glass carbon electrode (Pd-Cu/GCE). The modified electrode electrochemical properties of a preliminary study found that this modified electrode has good stability and electrochemical activity, experiments show that formic aicd has good voltammetric response of the electrode. The electrical activity of the formic acid in the Pd/GCE is lower than that in the Pd-Cu/GCE, this is due to the synergistic effect of the bimetal. When the Cu content is increased gradually in H₂PdCl₄ and CuSO₄ a mixed solution, the formic acid oxidation peak currentlower, because Cu has no electrocatalytic activity for formic acid oxidation.

Abstract: We have demonstrated the fabrication of novel poly(vinylbenzyl chloride)@lead sulfide (PVBC@PbS) core-shell nanospheres via the atom transfer reversible polymerization (ATRP) of lead dimethacrylate (Pb(MA)₂) initiated from methyl chloride groups on surfaces of PVBC nanoparticles and subsequent reaction with ethanethioamide. The chemical structure of the PVBC@PbS nanospheres was confirmed by the fourier transform infrared (FTIR) spectroscopy, and the morphology of the nanospheres were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The average size of the nanospheres was determined to be about 100 nm. The PVBC@PbS nanospheres were able to absorb phenol in the solution, and the balanced adsorption capability of phenol to nanospheres could reach to 7.2 μg/mg.

Abstract: The paper describes two methods of syntheses of iron oxides, microstructure and morphology of magnetite nanoparticles. Nanocomposite thin films of SiO₂/Fe₃O₄ have been prepared with sol-gel dip coating technique: dip-coating from SiO₂/Fe₃O₄ sol and encapsulation magnetite between two SiO₂ layers. Structural and morphological characteristics of iron oxides particles and prepared film were analyzed by X-Ray Diffraction, SEM, FTIR, DTA, AFM. AFM topography of surface and measurements of roughness has shown that using iron oxide encapsulation between two SiO₂ layers to provide the even distribution of iron oxide, results as high quality films with low R_q values 1.5 2.7 nm.

Abstract: A single SiC NW-FET (nanowire field effect transistor) was fabricated by FIB (Focus-Ion-Beam) method and the photo-electric properties of the device including I-V characteristic, transfer characteristic and time response et.al. were studied in this paper. SiC NWs (NWs) were prepared by pyrolysis of a polymer precursor with ferrocene as the catalyst by a CVD route. The NWs were suspended in ethanol by ultrasonic, then sprayed onto a silicon wafer with 300nm silicon oxide. Pt electrodes were deposited directly by FEI NanoLab 600i along with the SiC NW on silicon wafer. The transfer characteristic of the device shows that the SiC NW is a n-type semiconductor and photoelectrical measurements of the device show an rapid change of voltage when applied a constant current and explored the device to 254nm UV light. The mechanism of photo-electric properties are discussed in the last. Our results show that the single SiC NW FET could be applied to a harsh environment due to its own excellent electrical and optical properties.

Abstract: Polyurethane (PU) elastomers based on all kinds of polyether-polygol, diisocyanate and chain extender were prepared by two-step processes;the different influential factors of polyurethane elastomer were discussed in detail. The results showed that when the molecular weight of polyether-polygol increased, the hardnesstensile strength and tear resistance of polyurethane elastomer decreased, but the elongation at break increased;the property of polyurethane elastomer increased with the increasing perecentage of hard segment phase;R numerical value (-NCO/-OH) was controlled between 1.01 and 1.03;the shorter chain-extender had excellent microphase separation and mechanical properties;With the amount of 1, 4-butadiene alcohol (BDO) incrasing, the performance of polyurethane elastomer becomes well,but when the amount of 1, 4-butadiene alcohol comes to a point it appears reverse.

Abstract: A large polycarbonate plate molding with different thickness was conducted to investigate the differences between CIM and ICM. The results reveal that increase thickness can significantly reduce part shrinkage, and both part shrinkage and shrinkage difference of ICM are smaller than that of CIM. In addition, This study also shows the optical distortion is close relate to molding method and thickness, both ICM and thinner-wall can reduce the optical distortion.

Abstract: New types of ecologically benign surfactants with sugar as head groups (N-alkylglucosamides) have been described, namely, N-octylglucosamides (NOGA), N-dodecylglucosamides (NDGA), N-cetylglucosamides (NCGA). N-alkylglucosamides were characterized by Fourier transform infrared spectroscopy (FTIR) and ¹H Nuclear Magnetic Resonance (¹HNMR) respectively. N-alkylglucosamides was immobilized onto the surface of PPNWF by using Glycidyl methacrylate (GMA) as the linking agent. The chemical structure and composition of the modified PPNWF surface were analyzed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The surface properties were investigated by water contact angle. The water contact angles of the modified PPNWF decreased from 111° to 73°. The hemocompatibility of the modified PPNWF was evaluated by platelet adhesion. The number of platelets adhering to the modified surface was more dramatically reduced than that of the virgin surface. The results indicate that the modified surface of PPNWF by N-alkylglucosamides was a facile approach to construct biocompatible surface.