固体高分子水電解セルにおけるオゾン水生成の多層電極等による特性改善

抄録

Ozone is recently used for many purposes as an environmental friendly oxidant, so the ozone production device with high ozone concentration and low production energy is desired. One of the candidates for such device is the ozone water production by water electrolysis cell using the solid polymer electrolyte with PbO₂ anode catalyst, which has merits to be compact and to produce high-concentration ozone water directly by the deionized water electrolysis. In this study, we have tested ozone water production by changing electrodes and electrolytes constitution in order to improve the ozone production performance. Tested two electrolytes are Nafion117 and a membrane-electrode assembly (MEA) with Pt catalyst on cathode side of Nafion117. Tested two electrodes are mono-layer of Ti expanded metal and four different mesh layers of Ti expanded metal. Ozone water production tests are performed under long-term operations changing temperature and flow rate to optimize experimental conditions. The voltage-current characteristic for electrolysis cell have been improved significantly, when the electrode is four layers of Ti metal and the electrolyte is the MEA with Pt catalyst. The stable ozone water concentration has been obtained by operating the cell for about 8 hours. The optimum temperature and water flow rate for ozone water production are 25˜30° and 33L/h, respectively. Furthermore, the optimum overpotential was measured by a reference electrode at the cathode-side MEA, and the anode catalyst suitable for ozone water production was identified to be βPbO₂ by the X ray diffraction pattern.