The photoelectrochemical behavior of copper electrode in sodium borate solutions (pH 9.2) containing benzotriazole (BTA), carboxybenzotriazole methyl ester (CBTME) and carboxybenzotriazole butyl ester (CBTBE) was studied by using photoelectrochemical techniques. The photoresponse of the electrode in solutions containing the above compounds exhibited an n-type semiconductor action during anodic polarization. Based on the results of coupon tests, the inhibiting action of the additives was in the order of BTA > CBTME > CBTBE. The combination of BTA and CBTME had a synergistic effect, and the optimum ratio was found to be 2 mg/dm3 BTA and 3 mg/dm3 CBTME. The results obtained from the photoelectrochemical technique agreed well with those obtained from the coupon tests and AC impedance spectroscopy.
Photocatalytic oxidation reaction of trichloroethylene (TCE) in dried air was enhanced by the intermediates/products. Phosgene (COCl2), resulting from the photocatalytic oxidation reaction of TCE, was found to enhance the overall oxidation reaction of TCE in the present system in two ways; 1) photodissociation of COCl2 in the gas-phase gives Cl atoms by chlorine-photosensitized oxidation; 2) COCl2 may be adsorbed on the surface of TiO2 and may undergo oxidation produce Cl2.
A hydrogen gas sensor based on a Pt-thin SiO2-SiC structure is fabricated and the behavior for a mixed hydrogen and oxygen gas at 300°C is studied and compared with previously published results for Si-based devices. The voltage response for a constant current is found to depend on the square root of hydrogen partial pressure, and decreases with increasing oxygen gas concentration. The coverage ratio of hydrogen atoms for adsorption sites exhibits a consistent correlation with normalized partial pressure PH21/2/PO21/4 for all mixtures of hydrogen and oxygen examined. The surface reaction mechanism by which H2O is produced from adsorbed oxygen and hydrogen atoms is discussed based the results.
The electrodeposition of zinc from Lewis basic 1-ethyl-3-methylimidazolium bromide-zinc bromide molten salts with and without dihydric alcohols (ethylene glycol, 1,2-propanediol, 1,2-butanediol, or 1,3-butanediol) at 120°C were investigated. The 1-ethyl-3-methylimidazolium bromide-ZnBr2 binary bath gave neither metallic silver-colored deposits nor good cathodic current efficiencies. The addition of the dihydric alcohol improved the smoothness and color of the deposits and also increased the cathodic current efficiency at high current density. Of the four dihydric alcohols, ethylene glycol was superior to the other three alcohols in the smoothness and color of the deposit and the cathodic current efficiency.
The most important cause of lifetime limitation of molten carbonate fuel cell (MCFC) is dissolution of the cathode NiO and precipitation of nickel in the electrolyte. Porous cathodes of NiO, 1-10 mol% Fe-doped NiO, and 5-25 mol% Co-doped NiO for the MCFC were prepared and used for the bench scale cells at temperature of 923 K. A initiation time of nickel short-circuiting for 10 mol% Fe-doped NiO was 2.3 times longer than that of NiO cathode in spite of almost the same nickel precipitation rate in the Li/K matrix. Moreover, Li/Na cell applied 10 mol% Fe added in NiO cathode with advanced matrix achieved about 9 times longer lifetime than Li/K cell applied NiO cathode with conventional matrix. On the other hand, the cell performance using 10 mol% Fe-doped NiO cathode is lower than that of conventional NiO cathode because of the unsuitable microstructure of the cathode. The optimization of microstructure is of importance to apply the Fe-doped NiO cathode to the MCFC.