An electroanalytial study on the anode process of carbon electrode in LiF-NaF-KF melt was carried out by cyclic voltammetry (CV), chronoamperometry (CA), and gas chromatography. At the potentials higher than 3.7 V versus K+/K the anode effect appeared and generation of perfluorocarbons (PFCs) such as CF4 and C2F6 was observed from the same potential. At 1223 K, the current stayed at very lower level over the range of high potentials (>3.5 V), and only small amount of PFCs was detected, while at lower temperatures, large value of PFCs generation was observed from the potential higher than 7.0 V.
The anodic dissolution behavior of conductive titanium oxycarbide in NaCl–KCl melt was investigated in detail. An emphasis is on the anode gas was analyzed on-line using mass spectra when performing electrolysis. The results showed that TiCxOy can dissolve in alkali chloride melt. During the anodic dissolution, titanium component of TiCxOy dissolves as Ti2+ ion into the molten salt, and the components of carbon and oxygen form carbon monoxide (CO) simultaneously. A series of investigation has been focused on the influences of the current density and the concentration of Ti2+ on the anodic dissolution. An interesting result shows that the faradic dissolution ratio is significantly related to the anodic current density instead of the concentration of Ti2+.
The authors investigated the surface morphological change in mesophase-pitch carbon fibers microelectrode by the electrochemical oxidation in basic aqueous electrolyte. The scanning electron microscopic (SEM) observation of the carbon fiber consisting of optically anisotropic and isotropic parts revealed preferentially oxidative corrosion of the anisotropic domain to form pores on the electrode surface. The electrochemically oxidized anisotropic carbon fiber such as onion or radial type clearly showed the micro-structure derived from the orientation of the accumulated hexagonal carbon planes. Therefore, the electrochemical oxidation method can be considered as an effective technique for understanding the micro-structure of carbon materials, which is industrially important for mechanical and electrochemical properties.
Electrodeposition of aluminum from the AlCl3-EMIC ionic liquid containing saturated NdCl3 has been carried out by direct and pulse current plating. The effects of some parameters such as current density, pulse frequency, and on/off time ratio (ton/toff) on deposit morphology and crystal size have been investigated. The results showed that the microdeposits changed from polygon crystals to smaller-size spherical crystals as the direct current density increased. The deposits prepared by the pulse current plating gave brighter and flatter surface compared with those by the direct current plating at the same average current density. The deposits displayed dense and smooth surface with about 0.5 µm crystal size under the conditions of ton/toff=8:2, f=100 Hz, im=15 mA/cm2 at 25°C.
Double nanoparticles of Pt and SnO2 with different Pt/Sn ratios highly dispersed on Ketjen Black (denoted as Pt/SnO2/CB) were prepared by the modified Bönnemann method. The average size and standard deviation of the Pt and SnO2 nanoparticles were 3.1±0.5 nm and 2.5±0.3 nm for the Pt/SnO2(3:1)/CB, 3.0±0.5 nm and 2.6±0.3 nm for Pt/SnO2(1:1)/CB, 2.8±0.5 nm and 2.5±0.3 nm for Pt/SnO2(1:3)/CB. The Pt/SnO2(3:1)/CB showed the highest specific activity and lowest overpotential for ethanol oxidation reaction (EOR) in the present study, and was superior to a Pt/CB electrode. These were ascribable to the synergistic effect of Pt and SnO2 nanoparticles.