It was found that the addition of propargy alcohol (PA) to a nickel sulfamate solution was effective for controlling the shape of deposit in the process of nickel electrodeposition onto a micropatterned substrate. The factors, i.e. the electrode potential, the thickness of diffusion layer and the concentration of PA, that affect the shape control function of PA were simulated by the boundary element method, based on the assumption that PA is consumed by diffusion-adsorption-reduction mechanism and that the concentration of PA vary along the cathode/ solution interface. The function that represents the variation of PA concentration along the interface was used for the boundary values. The results of simulation explained well the difference in growing habit of the deposits obtained experimentally at different potentials, and figured out the important factors for suppressing the growth in horizontal direction. The optimum conditions for obtaining probe shape deposits were proposed.
Aluminum specimens covered with thick porous type anodic oxide films, up to 100μm, were irradiated by a photon rupture technique, a focused pulsed Nd-YAG laser beam, in a Ni2+ solution. The thick anodic oxide films, which does not dyed, were ruptured with numerous cracks by laser ablation. However, dyed thick anodic oxide films were removed layer by layer without developing cracks, as the dyed oxide film absorbed the laser energy. After laser irradiation, electroplating was attempted to form thick Ni layers at only the irradiated area. By this local electroplating, a Ni layer was found to deposit just at the irradiated area, as the pore sealed anodic oxide films acted as an insulating film.
Electrochemical reduction of molecular oxygen (O2) on an Hg adatom-modified Au electrode in an organic medium was subjected to cyclic voltammetry in order to clarify the catalytic effect of the surface of the Hg adatom-modified Au electrode in the reduction of O2 to hydrogen peroxide (HO2−). Acceleration of the disproportionation of superoxide ions (O2−) could be observed on the Hg adatom-modified Au electrode in organic media (DMF, AN) containing 2.5~3.5 mM H2O, whereas quasireversible O2/O2− redox reaction was observed on a bare Au electrode in the organic solution and on the Hg adatom-modified Au electrode in an organic medium, which had been thoroughly dehydrated. In addition, the extent of acceleration of the disproportionation of O2− was found to depend on the surface coverage (θ) of Hg on the Au electrode surface. These results suggest that the Hg adatom-modified Au electrode surface efficiently catalyzed the disproportionation of O2− by use of a small amount of H2O in an organic medium.
Immersion of an Au electrode coated with a self-assembled monolayer of alkanethiol in solution containing dispersed lipid liposomes forms a bilayer membrane of lipid layer and alkanethiol. Linear sweep voltammetry of the bilayer membrane-coated electrode shows reduction wave due to desorption of alkanethiol molecules. It was found that the peak potential of the reduction wave gave information concerning fluidity of the lipid layer. The electrochemical AC impedance measurements were found to be also useful for monitoring formation of the bilayer after addition of lipid liposomes in solution. Analysis of the changes in capacitance of the electrode with time has revealed that the formation of the bilayer membrane obeys the first-order kinetics.
National Space Development Agency of Japan (NASDA) is developing Polymer Electrolyte Fuel Cell (PEFC) systems for applications to transfer vehicles for short-term missions and larger spacecraft in the future. We first designed and manufactured a 1 kW-class fuel cell. Through our tests, we demonstrated that a humidifier is not necessary when using pure hydrogen and oxygen supplied from opposite directions. Furthermore, we prepared a dehydrator and demonstrated water removal from closed gas loop for future operations in a closed environment. We demonstrated more than 250 hours of operation with stable performance in a simulated closed environment.
When an activated carbon electrode containing carbon black CB or poly(3,4-ethylene dioxythiophene polystylenesulfonate) PEDOT was employed as the counter electrode of dye-sensitized solar cells, the energy conversion efficiency was improved compared to that of the solar cells with a sputtered pt counter electrode.