Effect of irradiation on electrode processes. Part 1.—The hydrogen electrode in dilute solutions

Abstract

The effect of ⁶⁰Co-γ and 1 MeV electron irradiation on the kinetics of the H₂—H⁺ exchange on platinum electrodes immersed in hydrogen-saturated dilute aqueous solutions (pH 1.04 to 3.9; no supporting electrolyte) was studied. The investigation was possible since the dissolved hydrogen facilitated the efficient radical chain decomposition of the electrochemically-active radiolytic hydrogen peroxide. Two principal radiation effects were observed: (i) exchange current densities were increased by amounts which were too large to be explained by the catalytic activity of the unstable intermediates. It was therefore proposed that radiation generates electrochemically active sites by the displacement of surface metal atoms. (ii) irradiation led to small negative shifts in the rest potential, the magnitudes of which were proportional to the dose rate and to the electrode polarization resistance. The shifts were either a consequence of the fact that irradiation accelerates anodic more than cathodic processes; or were due to the establishment of mixed potentials involving the H₂—H⁺ exchange (E₀= 0.0 V) and the oxidation of radiolytic hydrogen atoms (E₀=–2.1 V). Quantitative results favoured the former explanation.