CATALYTIC INFLUENCE OF COMMERCIAL RU, RH, PT, AND PD (SIMILAR-TO-0,1 ATOMIC PERCENT) INTERCALATED IN GRAPHITE ON THE HYDROGEN EVOLUTION REACTION

Graphite electrodes intercalated with various metals (Ni, Co, Pd, Pt, Rh, and Ru) have been bonded with an inorganic polymer LaPO4 and used as cathodes in the hydrogen evolution reactions (HER) in 1M KOH. Four of the most active electrodes showed very good mechanical and electrochemical stability. The overvoltage of the HER at j = 0.10 A cm-2 decreased in the following order: -525 mV, for pure graphite and -254, -137, -103, and -58 mV, for the Pd/C, Rh/C, Pt/C, and Ru/C electrodes, respectively. The kinetics of the HER for two electrodes (Ru/C and Pd/C) were measured with the use of an ac impedance technique. In both cases, the HER proceeds via the Volmer-Heyrovsky mechanism. The results obtained proved that the Pd/C electrode had a larger active surface area than the Ru/C one did.