Until recently, there had been only few in situ methods available for the structural determination of an electrode surface in solution at the atomic level. Now, several recent investigations have demonstrated scanning tunneling microscopy (STM) to be a powerful new technique for in situ characterization, with atomic resolution, of electrode surfaces under potentiostatic control. It has been demonstrated that the in situ STM makes it possible to monitor with atomic resolution a wide variety of electrode processes such as the adsorption of inorganic and organic species, the dissolution and deposition of metals and semiconductors. Owing to limitations on space, the focus is on the adsorption of organic molecules such as benzene and related compounds.
The electrochemical properties of the solid polymer electrolytes (SPE) containing lithium trifluoromethanesulfon imide (LiTFSI) and novel lithium sulfonates have been investigated. Sulfonates as additives into the LiTFSI-based SPE showed ionic conductivities up to 5.1 × 10−4 S·cm−1 at room temperature. Improvement of the ionic conductivity is attributed to the formation of the coordination centers in the system and an increase of amorphous degree of the SPE.
Photoelectrochemical deposition of metallic oxide (PbO2, RuOx, NiOOH, and CoOOH) onto a Ti substrate was studied and the electrochemical behavior of the prepared Ti/TiO2/MOx electrodes was examined. The photoelectrochemical deposition of MOx occurred in the solutions containing Mn+ ions on the Ti substrate under anodic bias. Electron holes produced on the TiO2 film surface under illumination may contribute the MOx formation. The prepared Ti/TiO2/MOx electrodes showed a tunneling current under anodic bias.
Electrodeposition of Sn-Cu alloy for use as Pb-free soldering was investigated. Pyrophosphate bath containing potassium iodide was used as a basic Sn-Cu alloy electroplating bath. Polyethylene glycol (mean molecular weight = 600: PEG600) and formaldehyde were used as additives. Electrochemical behavior, composition of electrodeposits, surface morphology and phase structure were studied. Copper content in deposits decreased with increasing current density and Sn-Cu alloys with the composition near the eutectic composition (Sn-1.3 at% Cu) were obtained in the range of current densities from 1 to 2 A dm−2. Dull Sn-Cu alloy was electrodeposited from the basic bath and the bright Sn-Cu alloy was obtained from the bath modified by adding both formaldehyde and PEG600 to the basic bath. It is suggested that the process of the reductive decomposition of formaldehyde on the alloy electrodeposit related to the smoothing of Sn-Cu alloy films. β-Sn phase only or two phases of β-Sn phase and η phase (Cu6Sn5 phase) were observed with the electrodeposited Sn-Cu alloys.
Titanium (IV) oxide (TiO2) was colored with brownish yellow by X-ray irradiation processing and the photocatalytic activity of thus treated TiO2 was improved under the light with longer wavelength, e.g. Xenon lamp, etc. Also, the photoelectrochemical characteristics of thus processed titanium oxide were evaluated for the investigation of the photocatalytic sensitization. It was found that the active wavelength region of thus treated TiO2 was shifted to longer wave-length which was attributed to the decrease in band gap of TiO2 by X-ray irradiation.
The purpose of this investigation was to study Sn-Cu alloy electroplating for Pb-free solder from acid sulfate baths (2 M H2SO4 + 0.2 M SnSO4 + 0.008 M CuSO4) containing N,N-bis (polyoxyethylene) octadecylarnine(POOA) by means of various electrochemical methods, scanning electron microscopic observation, X-ray diffractometry, etc. POOA was adsorbed on the electrode in the range of potentials from 0 to −1.2 V, and POOA adsorbed on the electrode exhibited strong inhibitory effect on the electrochemical reduction of Cu(II) ion. Needle-like or dendritic electrodeposits were obtained from acid sulfate bath in the absence of organic additives. On the other hand, block-like or granular crystals were observed on the whole surface by adding POOA. Sn-Cu alloy electrodeposits containing 2.8∼6.0 at%Cu were obtained from acid sulfate baths containing 1 mM POOA under galvanostatic conditions (0.5∼7.0 A dm−2). Cu contents in electrodeposits decreased with increasing the current density, and increased with increasing the concentration of CuSO4. Sn-Cu alloy electrodeposits consist of β-Sn phase and η(Cu6Sn5) phase, and its solidus temperature is 227°C.
CoO/Ni composite particle was prepared from filament shape Ni particle as a cathode material for Molten Carbonate Fuel Cells (MCFCs) by a mechanical coating technique. The composite particle had the morphology consisted of a Ni grain coated with fine CoO particles without changing the filament structure. Moreover, the composite cathode was successfully fabricated from the CoO/Ni composite particles by a doctor blade tape casting method. The composite cathode had homogenous porous structure with good connections of grains. It suggests that a large sized composite cathode can be fabricated by the usual tape casting technique. Also, Ni solubility of the composite cathode into (Li0.62K0.38)2CO3 melt at 650°C in 30% CO2-70% air atmosphere was about half of that of NiO. The cathode activity and IR of the composite cathode was almost the same as that of the usual NiO cathode. As a result, it is concluded that the composite cathode can be used as a new cathode for MCFCs which achieves its high stability in the carbonate melt and the large sized composite cathode.
The photosynthetic reaction center complex was immobilized on a p-benzoquinonethiol-modified Au electrode. The potential of the reaction center-immobilized Au electrode in 0.1 M (M = mol/dm3) Tris-HCl buffer (pH 7.5) was shifted, upon illumination, to the negative direction, and the value increased with increasing the intensity of incident light. In addition, the potential shift was enhanced by adding cytochrome c2 to the solution. A photogalvanic cell was constructed only using this electrode, cytochrome c2, and an ITO electrode with hydrophilic surface, and the cell performance was examined. The open-circuit photovoltage and the short-circuit photocurrent were about 5 mV and 40 nA, respectively.