Kinetics of the electrochemical evolution of isotopically enriched gases. Part 3.—Hydrogen and deuterium evolution on platinum and platinised tungsten trioxide

Abstract

The kinetics of the electrochemical evolution of deuterium from solutions of sodium sulphate on platinised platinum electrodes enriched with adsorbed deuterons have been fitted to a theoretical model which yielded values for the coverage of deuterium and the total number of surface sites responsible for the reaction. The number of sites agreed with that determined from hydrogen stripping. The kinetics of the removal of adsorbed deuterium on allowing the electrode to stand in air at open-circuit voltage (OCV) were consistent with a second-order recombination with k₂= 0.02 s^–1 for da/dt=k₂a², where a is the fractional coverage of deuterium at the electrode. The numbers of sites and the volume of deuterium evolved measured for a series of platinised tungsten trioxide electrodes showed spillover of hydrogen from platinum to tungsten trioxide, in agreement with earlier theories.