Abstract: In the electrochemical devices with the proton exchange membrane(PEM) as the ion conductor the surface diffusion of the adsorbed intermediates impels the catalyst particles which are not in contact with the PEM to take part in the electrode reaction,and thus increases the utilization efficiency of the catalyst. In this paper,a specially designed experimental device based on the planar Au as the working electrode has been used to study the surface diffusion and the recombination reaction of overpotential-deposited(OPD) H-atoms in the process of the HER on the gold surface. In the chronoamperometric experiment,it was observed that the experimental current increases due to the surface diffusion and recombination reaction of the OPD H-atoms on the surface of gold. Under the supposed kinetic model,the numeric analysis has been done,and the surface concentration of the OPD H-atoms as the function of the reaction potential,the surface diffusion coefficient and the kinetic constant of surface recombination reaction were obtained by fitting current obtained experimentally.

Key words: Au electrode, Surface diffuse, Adsorbed intermediate, Hydrogen evolving reaction