RUTHENIUM DIOXIDE AS CATHODE MATERIAL FOR HYDROGEN EVOLUTION IN HYDROXIDE AND CHLORATE SOLUTIONS

Ruthenium dioxide as electrocatalyst on an activated cathode f or chlo rate production was investigated with respect to its activity towards hydrogen evolution, hypochlorite reduction, and chlorate reduction, re spectively Investigations were made in the presence, as well as in the absence, of a chromium hydroxide film in 1M NaOH and in typical chlor ate electrolyte. Low overvoltages for hydrogen evolution were found an d, at technical current densities, an effect of catalyst coating thick ness. Commercial DSA(R) electrodes with RuO2 as the active compound we re tested as cathodes and were less active but more stable than the co atings produced by us. Hypochlorite and chlorate were reduced in the a bsence of chromate, chlorate reduction being fast on ruthenium dioxide compared to the other electrode materials and by far the dominating c athodic reaction in chlorate electrolyte without chromate and hypochlo rite at 70-degrees-C, 3 kA/m2.