Formation of RuO(OH)2 on RuO2-Based Electrodes for Hydrogen Production

The catalytic and durable electrode coating of ruthenium dioxide (RuO 2 ), applied on nickel (Ni) substrates, is today utilized as electrocatalytic cathodes for hydrogen production, e.g., in the chlor-alkali process and alkaline water electrolysis. The drawback is, however, the sensitivity to reverse currents obtained during power shutdowns, e.g., at maintenance, where the RuO 2 -based electrodes can be severely damaged unless polarization rectifiers are employed. Through the material characterization techniques X-ray diffraction and X-ray photoelectron spectroscopy, we can now reveal that RuO 2 coatings, when exposed to hydrogen evolution at industrially relevant conditions, transforms into ruthenium oxyhydroxide (RuO(OH) 2 ). The study further shows that as the hydrogen evolution proceeds the formed RuO(OH) 2 reduces to metallic ruthenium (Ru).