HYDROGEN ELECTRODE-REACTION ON ELECTRODES OF GLASSY CARBON-SUPPORTED ULTRAFINE PD PARTICLES IN ALKALINE MEDIA

The hydrogen electrode reaction on electrodes of ultrafine Pd particles supported on flat glassy carbon substrates (Pd/GC) was investigated by means of cyclic voltammetry. Reduction and oxidation currents of hydrogen were resolved into those due to adsorption, absorption and evolution of hydrogen, as well as their corresponding re-oxidation currents. Two types of hydrogen species adsorbed at Pd/GC electrodes were identified; one was a weakly bound species which was readily oxidized, and the other was a strongly bound species which was removed at a higher potential. The capacity of Pd/GC for hydrogen absorption diminished with the decrease of particle size, presumably because of the decrease in the fraction of bulk Pd atoms in Pd particles.