Structural modification of PdAg alloy induced by electrolytic hydrogen absorption

Abstract

The palladium (79%) silver (21%) alloy has been characterized in respect to the permeation efficiency of electrolytically produced hydrogen. The effect of discontinuous electrolysis on permeation performance has been discussed as well as methods for Pd-Ag electrode reactivation. The structural changes of PdAg alloy, induced by electrolytic hydrogen adsorption, have been analyzed in details and were correlated with the H/Pd atomic ratio. By performing the electrolysis for well defined time, we managed to control the H/Pd ratio over the whole range of alpha- and beta-phase stability, as defined by phase diagram. The beta-phase formation was accompanied with surface corrugation of Pd-Ag alloy. As we determined, surface corrugation caused the occurrence of ghost peak in XRD spectra of PdAg alloy that coincides with the alpha-phase peak, thus influencing its resolution. Also, the criteria that should be taken into account when analyzing XRD data of H PdAg alloy were established. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.