Papers by Keyword: Composite Electrode

Abstract: Property investigation of co-doped 4 mol% scandia and 4 mol% yttria zirconia (Sc_0.08Y_0.08Zr_0.84O_1.92 or 4Sc4YSZ) synthesized via solid-state reaction (SSR) and all-alkoxide sol-gel (SG) method as precursor powders with LSM as composite electrode was conducted. The microstructure and morphology of the precursor powders and resulting LSM-4Sc4YSZ bulk composite electrodes were characterized. The results revealed that the 4Sc4YSZ was successfully synthesized via SG with more distinct cubic phases and finer particles than 4Sc4YSZ prepared via SSR. A more homogeneous and uniform distribution for LSM-4Sc4YSZ SG was also observed with a porosity of 30.65%. Moreover, using electrochemical impedance spectroscopy (EIS), the LSM-4Sc4YSZ SG revealed a total conductivity of 0.158 S/cm at 700 °C with an activation energy of 0.018 eV.

Abstract: A new synthetic procedure to Metal/metal sulfide hierarchical pore array composites was described. That is, a layer of Ni-Co-S nanoflakes was in situ constructed on the Ni ordered bowl-like micro/nanoarrays through a two-step electrodeposition method with the assistance of a colloidal sphere template. Such as-grown hierarchical composites could increase the specific surface areas and provide more active sites for electrocatalytic reactions. It exhibited a high catalytic activity to glucose, with a high sensitivity of 1210.1 μM‧mM^-1cm^-2 and a wide linear range from 0.5 μM to 2.0 mM. This work provides another candidate material for the development of planar non-enzymatic glucose sensors.

Abstract: Utilizing two different synthesis methods, solid-state reaction and glycine-nitrate process, composite lanthanum strontium manganite and yttria-stabilized zirconia (LSM-YSZ) powders were prepared. The powders were then mixed with 0, 5, and 10 wt% carbon black nanosized pore former and pressed into 10mm diameter pellets then sintered at 1150 °C for 5 hours. The pellet composition and microstructure were investigated using FTIR, XRD, SEM-EDX, and their density and open porosity were measured using the Archimedes principle. The resulting microstructure of the composite pellets obtained using the two fabrication methods and different pore former weight percentages were studied and compared. It was found that the addition of 5 wt% carbon black pore former yields about 40% desired open porosity, and synthesis via GNP results to finer and more evenly distributed LSM and YSZ particles.

Abstract: Nickel foam-based Ni-Mo alloy electrodes, Ni+Mo composite electrodes and Ni+Mo/Ni-Mo composite alloy electrodes were prepared by eletrodeposition, and the electrocatalytic characteristics for hydrogen evolution reaction (HER) in 30wt% KOH solution were investigated by cathode polarization curve and electrochemical impedance spectroscopy (EIS). The experimental results show that in comparison with nickel foam electrodes, these electrodes exhibit a lower overpotential, a higher exchange current density and a larger real surface area for HER. At 30°C and current density of 200 mA/cm², the overpotentials of foam Ni electrodes, nickel foam-based Ni-Mo alloy electrodes, Ni+Mo composite electrodes, Ni+Mo/Ni-Mo electrodes are respectively 506, 252, 336, 202 mV. The nickel foam-based Ni+Mo/Ni-Mo composite alloy electrode had the highest HER electrocatalytic activity.

Abstract: As the fabrication technology of the composite electrode becomes sophisticated, the understanding of the detailed knowledge of the microstructure’s effect on the electrochemical process is essential for the commercializing of the solid oxide fuel cell (SOFC). In this paper, an equivalent circuit for the SOFC structure is proposed to clearly describe the electronic electric current transfer process, ionic electric current transfer process and the charge transfer process at the electrochemical reaction interface between electronic and ionic conducting materials. And types of the boundary condition setting constraints for the developing of the multi-physics coupling numerical model of SOFC are obtained basing on the electrochemical kinetic analysis.

Abstract: Copper based metal matrix composite reinforced with Boron Carbide is a newly developed Electrical Discharge Machining (EDM) electrode showing better performance than the conventional copper based electrode. Right selection of machining parameters such as current, pulse on time and pulse off time is one of the most important aspects in EDM. In this paper an attempt has been made to develop mathematical models for relating the Material Removal Rate (MRR), Tool Removal Rate (TRR) and Surface roughness (Ra) to machining parameters (current, pulse-on time and pulse-off time). Furthermore, a study was carried out to analyze the effects of machining parameters on various performance parameters such as, MRR, TRR and Ra. The results of Analysis of Variance (ANOVA) indicate that the proposed mathematical models, can adequately describe the performance within the limits of the factors being studied. Response surface modeling is used to develop surface and contour graphs to analyze the effects of EDM input parameters on outer parameters.

Abstract: Composite electrodes based on vertically aligned multi-walled carbon nanotubes (MWCNTs) coated with vanadium oxide (V₂O₅) have used in supercapacitors. The vanadium (V) oxide (V₂O₅) cathodically deposited on titanium collector in vanadium oxide solution. The novel supercapacitor performed by V₂O₅/MWCNTs/Ti electrode in 1.0 M HCl aqueous solution can reach a specific capacitance of 713.3 F/g at 10 mV/s, which is larger than that of MWCNTs/Ti. To characterize the V₂O₅/MWCNTs/Ti composite electrode, cyclic voltammetry and galvanostatic charge-discharge method were executed, and the morphology of the composite electrode was examined by scanning electron microscope. This nanocomposite electrode greatly enhanced the utilization efficiency of supercapacitor electrode material, low material cost and provided both high capacitance and power density.

Abstract: TiO_2-xN_x film was prepared by the combination of sol-gel and spin-coating method on indium-tin oxide (ITO) conducting glass substrate. Then an ITO/TiO_2-xN_x/NiO composite electrode was obtained by chemical bath deposition (CBD). The morphology, crystal structure and composition of the ITO/TiO_2-xN_x film were characterized by SEM, XRD, and XPS. The photoelectrochemical properties of the ITO/TiO_2-xN_x/NiO electrode were evaluated by photocurrent transient measurements and UV-visible transmittance spectra. The results showed that the ITO/TiO_2-xN_x/NiO electrode was sensitive to light and exhibited a noticeable photoelectrochromism.

Abstract: The electrochemical performance of capacitor was studied with LiCoO₂/AC as composite cathode and activated carbon (AC) as anode, in 1.0 mol/L LiPF₆/EC+DMC electrolyte. Cyclic Voltammetary, Constant-Current Charge and Discharge, Electrochemical Impedance Spectrum (EIS) and Leakage Current Test were tested to study the characteristics of supercapacitors. The results illustrate that recharging voltage of hybrid supercapacitor can reach to 3.0 V and show good capacitance characteristics. The supercapacitor can rapidly charge and discharge and show good cycling performance. There is a great effect to the performance of the capacitors by adopting different proportional composite electrode. When the ratio of composite electrode is 6:4, we get maximum symmetrical Cyclic Voltammetary and short charge-discharge time only 26.4min; When the ratio is 7:3, the minimum AC impedance of 26.2W can be attained and least leakage current is only 19.92mA/g; When the ratio is 5:5, the best first specific capacity can reach to 70.17F/g but a lower capacity retention rate is 74.86%.

Abstract: In this study, polyaniline (PANI) was prepared by electrochemical method on the surface of active carbon (AC) electrodes. The physical and electrochemistry properties of AC/PANI composite compared with pure AC electrode were investigated by scanning electronic microscope (SEM), galvanostatic charge/discharge test and electrochemical impedance spectroscopy (EIS). The AC/PANI composite electrodes showed much higher specific capacitance (624 F•g-1), better power characteristics and were more promising for application in capacitor than pure AC electrodes.