Hydrogen transport through rf-magnetron sputtered amorphous WO3 film with three kinds of hydrogen injection sites

Abstract

The present work is aimed at investigating hydrogen transport through rf-magnetron sputtered amorphous WO3 film/indium tin oxide glass in the presence of hydrogen trap sites under impermeable boundary condition in 0.1 M H2SO4 solution by using cyclic voltammetry and ac-impedance technique, combined with potentiostatic current transient technique. From the experimental results, it was substantiated that three kinds of hydrogen injection sites, i.e., reversibly active site, shallow trap site (reversible trap site) and deep trap site (irreversible trap site) exist in the WO3 film. The way how to semi-quantitatively determine the amount of the deep trap site was proposed, based upon the Mott-Schottky relation. On the basis of the current transients (chronoamperometry) numerically simulated for the impermeable modified electrode having the trap sites, the results of successive current transients were analysed to satisfactorily describe the hydrogen transport kinetics through the impermeable modified WO3 film electrode.