Left : virgin Palladium sample (wire, as drawn).
Right : the same sample but after 50 cycles (hydrogenation / dehydrogenation), done electrolytically at 25 °C.
Unpublished results (in 2009) from : P. Tripodi, N. Armanet, V. Asarisi, A. Avveduto, A. Marmigi, J.D. Vinko, J.-P. Biberian.
This picture is linked to : The effect of hydrogenation/dehydrogenation cycles on palladium physical properties, Physics Letter A, 373 (2009) 3101-3108.