Structural modification of PdAg alloy induced by electrolytic hydrogen absorption

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 re-activation. 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 α- and β-phase stability, as defined by phase diagram. The β-phase formation was accompanied with surface corrugation of PdAg alloy. As we determined, surface corrugation caused the occurrence of “ghost” peak in XRD spectra of PdAg alloy that coincides with the α-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.