Cathodes for chlorate electrolysis with nanocrystalline Ti-Ru-Fe-O catalyst

Cathodes for chlorate electrolysis were prepared by mixing nanocrystalline Ti-Ru-Fe-O catalyst powder with small amounts of Teflon and subsequent hot pressing on a carbon-Teflon sublayer. Initially, the electrode materials were characterized by SEM, EDX, XRD and BET measurements. The behaviour of electrodes with catalyst loadings from 300 mg cm(-2) reduced to 10 mg cm(-2) was investigated in chlorate electrolyte with pH 6.5 and in part, for comparison, in 1 M sodium hydroxide solution at 70 degrees C. Several methods have been used: cyclic voltammetry for the determination of double layer capacitance, Tafel plot analysis, cathodic potentiodynamic polarization and potentiostatic tests at i = -250 mA cm(-2). The as-milled catalyst powder electrodes showed a high activity for the HER in chlorate electrolyte particularly expressed in low overpotentials of about 580 mV at -250 mA cm(-2) for catalyst loadings down to 20 mg cm(-2) and high double layer capacitances in the freshly prepared state. These electrodes show increased activity at low polarization. The long-term stability during electrolysis was also analysed.