Dendrimer films as matrices for electrochemical fabrication of novel gold/palladium bimetallic nanostructures

Electrodeposition of novel Au/Pd bimetallic nanostructures with dendrimer films as matrices has been reported. The dendrimers exhibited highly open structures arising from protonation of amines and this made them have good penetrability for solvent molecules. The unique properties of dendrimers obviously affected the morphologies and compositions of deposited bimetallic nanostructures compared with those from unmodified surfaces. Field-emitted scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy and UV-vis spectroscopy were used to characterize these nanostructures.

The electrochemical behavior of a system with a limited number of molecules

In this paper, based on Einstein relationship between diffusion and random walk, the electrochemical behavior of a system with a limited number of molecules was simulated and explored theoretically. The transition of the current vs time responses from discrete to continuous was clearly obtained as the number of redox molecules increased from 10 to 10(6).

Rapid label-free detection of metal-induced Alzheimer's amyloid beta peptide aggregation by electrochemical method

Amyloid beta peptide plays a critical role in the pathogenesis of Alzheimer's disease (AD). Metal ions are highly enriched in cerebral amyloid deposits in AD and are proposed to be able to mediate A beta conformation. Therefore, a rapid, low-cost, and sensitive detection of metal-induced A beta aggregation and their relation to AD is clearly needed for the clinical diagnosis and treatment. In this report, we study metal-induced A beta aggregation by a rapid, label-free electrochemical method and monitor both the aggregation kinetics and the morphology in the absence or presence of Zn (II) and Cu (II).

Fabrication and electrochemical characterization of electrostatic assembly of polyelectrolyte-functionalized ionic liquid and Prussian blue ultrathin films

Polyelectrolyte-functionalized ionic liquid (PFIL) and Prussian blue (PB) nanoparticles were used to fabricate ultrathin films on the ITO substrate through electrostatic layer-by-layer assembly method. Multilayer growth was examined by UV-vis spectroscopy and cyclic voltammetry. The resulting ITO/(PFIL/PB)n electrode showed two couples of well-defined redox peaks and good electrocatalytical activity towards the reduction of hydrogen peroxide.

Electrochemical hydrogen storage in (Ti1-xVx)(2)Ni (x=0.05-0.3) alloys comprising icosahedral quasicrystalline phase

For (Ti1-xVx)(2)Ni (x = 0.05,0.1,0.15,0.2 and 0.3) ribbons, synthesized by arc-melting and subsequent melt-spinning techniques, an icosahedral quasicrystalline phase was present, either in the amorphous matrix or together with the stable Ti2Ni-type phase. With increasing x values, the maximum discharge capacity of the alloy electrodes increased until reached 271.3 mAh/g when x = 0.3. The cycling capacity retention rates for these electrodes were approximately 80% after a preliminary test of 30 consecutive cycles of charging and discharging.

Electrochemical corrosion behavior of Mg-5Al-0.4Mn-xNd in NaCl solution

The electrochemical corrosion behavior of Mg-5Al-0.4Mn-xNd (x = 0, 1, 2 and 4 wt.%) alloys in 3.5% NaCl solution was investigated. The corrosion behavior of the alloys was assessed by open circuit potential measure, potentiodynamic polarization, and electrochemical impedance spectroscopy. The electrochemical results show the intermetallic precipitates with Nd behave as less noble cathodes in micro-galvanic corrosion and suppress the cathodic process. During corrosion, Al2O3 and Nd2O3, in proper ratio, is incorporated into the corrosion film, and enhances the corrosion resistance.

Electrochemical Hydrogen Storage in Ti1.6V0.4Ni1-xCox Icosahedral Quasicrystalline Alloys

The discovery of the icosahedral phase (i-phase) in rapidly quenched Ti1.6V0.4Ni1-xCox (x=0.02-01) alloys is described herein. The i-phase occurs in a similar amount relative to the coexisting beta Ti phase. The electron diffraction patterns show the distinct spot anisotropy, indicating that the i-phase is metastable. The electrochemical hydrogen storage performance of these five alloy electrodes are also reported herein. The hydrogen desorption of nonelectrochemical recombination in the cyclic voltammetric (CV) response exhibits the demand for electrocatalytic activity improvement.

ELECTROCHEMICAL DEPOSITION OF MAGNESIUM IN ETHEREAL GRIGNARD SALT SOLUTION WITH IONIC LIQUID ADDITIVE

The electrochemical deposition of magnesium was investigated in ethereal Grignard salt solution with tetraethylammonium bistrifluoro-methanesulfonimidate additive, using cyclic voltammetry, potentiostatic transients, and scanning electron microscope measurements. The voltammograms showed the presence of reduction and oxidation peaks associated with the deposition and dissolution of magnesium. From the analysis of the experimental current transients, it was shown that the magnesium deposition process was characterized as a three-dimensional nucleation. The deposited product obtained from potentiostatic reduction presented a generally uniform and dense film.

Crystallographic and electrochemical characteristics of Ti45Zr35Ni13Pd7 melt-spun alloys

Ti45Zr35Ni13Pd7 alloys are prepared by melt spinning at different cooling rates (v). The phase structure and electrochemical hydrogen storage performance are investigated. When U is 10 m/s, the alloy consists of icosahedral quasicrystalline phase (I-phase), C14 Laves phase and a little amorphous phase. When v increases to 20 or 30 m/s, a mixed structure of I-phase and amorphous phase is formed. Maximum discharge capacity of alloy electrode decreases from 156 mAh/g (v = 10 m/s) to 139 mAh/g (v = 30 m/s) with increasing v. High-rate discharge ability at the discharge current density of 240 mA/g decreases monotonically from 61.2% (v = 10 m/s) to 56.8% (v = 30 m/s).

3D Fe3S4 flower-like microspheres: high-yield synthesis via a biomolecule-assisted solution approach, their electrical, magnetic and electrochemical hydrogen storage properties

Well-defined 3D Fe3S4 flower-like microspheres were synthesized via a simple biomolecule-assisted hydrothermal process for the first time. On the basis of a series of contrast experiments, the probable growth mechanism and fabrication process of the products were proposed. The electrical conductivity property of the as-synthesized Fe3S4 sample exhibited a rectifying characteristic when a forward bias was applied for the bottom-contacted device. The magnetic properties of the products were studied as well and the results demonstrated that the products presented ferromagnetic properties related to the corresponding microstructure. In addition, we first verified that the Fe3S4 flower-like microspheres could store hydrogen electrochemically, and a discharge capacity of 214 mA h g(-1) was measured without any activation under normal atmospheric conditions at room temperature.

Crystallographic and electrochemical characteristics of Ti-Zr-Ni-Pd quasicrystalline alloys

Ti45Zr35Ni20-xPdx (x = 0, 1, 3, 5 and 7, at%) alloys were prepared by melt-spinning. The phase structure and electrochemical hydrogen storage performances of melt-spun alloys were investigated. The melt-spun alloys were icosahedral quasicrystalline phase, and the quasi-lattice constant increased with increasing x value. The maximum discharge capacity of alloy electrodes increased from 79 mAh/g (x = 0) to 148 mAh/g (x = 7). High-rate dis-chargeability and cycling stability were also enhanced with the increase of Pd content. The improvement in the electrochemical hydrogen storage characteristics may be ascribed to better electrochemical activity and oxidation resistance of Pd than that of Ni.

Effect of La-Mg-based alloy addition on structure and electrochemical characteristics of Ti0.10Zr0.15V0.35Cr0.10Ni0.30 hydrogen storage alloy

Effect of La-Mg-based alloy (AB(5)) addition on Structure and electrochemical characteristics of Ti0.10Zr0.15V0.35Cr0.10Ni0.30 hydrogen storage alloy has been investigated systematically. XRD shows that the matrix phase structure is not changed after adding AB(5) alloy, however, the amount of the secondary phase increases with increasing AB(5) alloy content. The electrochemical measurements show that the plateau pressure Ti0.10Zr0.15V0.35Cr0.10Ni0.30 + x% La0.85Mg0.25Ni4.5Co0.35Al0.15 (X = 0, 1, 5, 10, 20) hydrogen storage alloys increase with increasing x, and the width of the pressure plateau first increases when x increases from 0 to 5 and then decreases as x increases further, and the maximum discharge capacity changes in the same trend.

Simultaneous electrochemical determination of uric acid, dopamine, and ascorbic acid at single-walled carbon nanohorn modified glassy carbon electrode

Single-walled carbon nanohorn modified glassy carbon electrode (SWCNH-modified GCE) was first employed for the simultaneous determination of uric acid (UA), dopamine (DA), and ascorbic acid (AA). The SWCNH-modified GCE displayed excellent electrochemical catalytic activities. The oxidation overpotentials of UA, DA, and AA decrease significantly and their oxidation peak currents increase dramatically at SWCNH-modified GCE. Linear sweep voltammetry (LSV) was used for the simultaneous determination of UA, DA, and AA in their ternary mixture. The peak separations between UA and DA, and DA and AA are large up to 152 mV and 221 mV, respectively.

Determination of Cd2+ and Pb2+ on glassy carbon electrode modified by electrochemical reduction of aromatic diazonium salts

Carbon modified by the reduction of aromatic diazonium derivatives was first used as electrode for the electrochemical stripping analysis of heavy metals. As a model, the glassy carbon electrode was modified with benzoic acid by electrochemical reduction of diazobenzoic acid, and the resulting modified electrodes were used for determination of Cd2+ and Pb2+. The anodic peak currents of cadmium and lead at the benzoic acid-modified glassy carbon electrode are 7.2 and 6 times of that at the bare glassy carbon electrode. A linear response was observed for Pb2+ and Cd2+ in the range of 0.5-50 mu g/l.

Effect of substitution of chromium for nickel on structure and electrochemical characteristic of Ti0.26Zr0.07V0.24Mn0.1Ni0.33 multi-phase hydrogen storage alloy

Ti-Zr-V-Mn-Ni-based multi-component alloys demonstrate high discharge capacity in KOH electrolyte. However, the drastic decrease in their discharge capacities makes them unsuitable for use as negative electrode material in the Ni/MH battery. In present work, Ni is partially replaced by Cr in the Ti-Zr-V-Mn-Ni-based alloys to improve their cycle life. The effects of Cr substitution on microstructures and the electrochemical characteristics of the alloys are investigated. It is found that Cr substitution is very effective to improve the cyclic durability of the alloys although the discharge capacity decreases with changing x from 0.05 to 0.20. Some kinetic performances have been also investigated using electrochemical impedance spectroscopy (EIS) and potentiostatic discharge technique.