In situ characterization of hydrogen absorption in nanoporous palladium produced by dealloying.
Palladium is a frequently used model system for hydrogen storage. During the past few decades, particular interest was placed on the superior H-absorption properties of nanostructured Pd systems. In the present study nanoporous palladium (np-Pd) is produced by electrochemical dealloying, an electrochemical etching process that removes the less noble component from a master alloy. The volume and electrical resistance of np-Pd are investigated in situ upon electrochemical hydrogen loading and unloading. These properties clearly vary upon hydrogen ad- and absorption. During cyclic voltammetry in the hydrogen regime the electrical resistance changes reversibly by almost 10% upon absorbing approximately 5% H/Pd (atomic ratio). By suitable loading procedures, hydrogen concentrations up to almost 60% H/Pd were obtained, along with a sample thickness increase of about 5%. The observed reversible actuation clearly exceeds the values found in the literature, which is most likely due to the unique structure of np-Pd with an extraordinarily high surface-to-volume ratio.
Institute of Materials Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria.
Eva-Maria
EM
Steyskal
Institute of Materials Science and Welding, Graz University of Technology, Kopernikusgasse 24, A-8010 Graz, Austria.
Christopher
C
Wiednig
Institute of Materials Science and Welding, Graz University of Technology, Kopernikusgasse 24, A-8010 Graz, Austria.
Norbert
N
Enzinger
Institute of Materials Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria.
Roland
R
Würschum
dealloying; dilatometry; hydrogen storage; nanoporous palladium; resistometry