Improving Characteristics of Ozone Water Production with Multilayer Electrodes and Operating Conditions in a Polymer Electrolyte Water Electrolysis Cell

Recently, ozone is used for many purposes as an environmentally friendly oxidant. An ozone production device with high ozone concentration and low production energy is therefore desired. One candidate for such a device is ozone water production in a water electrolysis cell using a solid polymer electrolyte with anode catalyst. Such a device would have the advantages of being compact and producing high-concentration ozone water directly through deionized water electrolysis. We have studied ozone water production with different electrode and electrolyte compositions and operation conditions, with the aim of improving ozone production performance. The two electrolytes tested were Nafion 117 and a membrane electrode assembly (MEA) with Pt catalyst on the cathode side of Nafion 117. The two electrodes tested were a single layer of Ti expanded metal and four layers of Ti-expanded metal with different meshes. Ozone water production tests were performed for many hours with changes in temperature, water flow rate, current density, current interruption time, and other factors to optimize experimental conditions. The voltage–current characteristics of water electrolysis cell were improved significantly when the electrode was four layers of Ti-expanded metal and the electrolyte was MEA with Pt catalyst on the cathode. Stable ozone water concentration was obtained after the cell had been operated for about 8 h. The optimum temperature, water flow rate, and current density for ozone water production are 25–30°C, , and , respectively. Further, the noninterrupted supply of small current suppressed the performance deterioration of ozone water production by current interruption, and the ozone production energy was reduced by supply of oxygen to the cathode.