NEW CATHODE MATERIALS FOR CHLORATE ELECTROLYSIS

Nanocrystalline Ti-Ru-O alloys of different composition were made by h igh-energy ballmilling Ti and RuO2 powders. Upon milling, RuO2 reacted with Ti to form Ti oxides. Ru-like hexagonal-close-packed (hcp) phase , and a cubic Ti-Ru(O) alloy. After 40 h of milling, the final product was primarily a Ti-Ru-O alloy with iron impurities from the steel bal ls and crucible. A high ball-to-powder weight ratio resulted in higher impurity (iron) content. Most of the iron in the powder did not exist as alpha-Fe particles but entered into the alloy lattice forming a Ti -Ru-(Fe)-(O) cubic phase. The incorporation of iron did not affect the catalytic performance very much. The electrocatalytical activity of t he studied cathode materials for the hydrogen evolution reaction (HER) in a chlorate electrolyte was investigated by measuring the overpoten tial at 250 mA/cm(2) current density (eta(250)) Good performance was f ound for Ti/RuO2 ratios of 2:1 and 3:1. The HER eta(250) values for th ese electrodes were 300 mV lower than that for mild steel cathodes. Th e electrodes made of the new alloys were very stable in the chlorate e lectrolyte and had good resistance to poisoning from the solution. The origin of the catalytic activity resulted mainly from ruthenium, and the presence of titanium and oxygen in the alloys was indispensable fo r the stability of the electrodes.