Hydrogen Transport through Rf-magnetron Sputtered Amorphous and Crystalline WO3 Films with Hydrogen Trap Sites

Abstract

The present work is aimed at investigating hydrogen transport through amorphous WO(3) (a-WO(3)) and crystalline WO(3) (c-WO(3)) films prepared by rf-magnetron sputtering onto indium tin oxide(ITO) glass under impermeable boundary condition in 0.1 M H(2)SO(4), solution by using Fourier transform infra-red(FTIR) spectroscopy, cyclic voltammetry, potentiostatic current transient technique and ac-impedance technique. The FTIR spectra showed that the a-WO(3) film contained water, apart from the c-WO(3). From the results obtained form the electrochemical experiments, it was suggested that the different behaviours in cyclic voltammograms between a- and c-WO(3) films result from an open-structured nature of a-WO(3) film containing H(2)O, which does not exist in the c-WO(3) film and there are three kinds of hydrogen injection sites in the films, i.e., reversibly active site, shallow trap site(reversible trap site) and deep trap site(irreversible trap site). The Mott-Schottky approach permitted us to semiquantitatively determine the amount of the deep trap site.