DescriptionNanoporous (np) metals produced by dealloying, a selective (electro-)chemical etching process, exhibit a high surface-to-volume-ratio and macroscopic sample sizes in three dimensions. This unique combination makes np-metals attractive for basic research as well as technology applications such as sensing, energy storage or (electro-)catalysis.
Various parameters of the dealloying process may sensitively influence the outcoming nanostructure. In the present work, the etching process of np-Au and np-Pt is investigated in-situ by resistometry, dynamically monitoring the entire macroscopic sample. This perfectly complements earlier studies, which were either performed ex-situ and/or restricted to microscopic portions of material.
During dealloying, the resistance increases by about three orders of magnitude. A model is developed which describes the observed characteristics to be governed by the dissolution of the master alloy in favor of the nanoporous structure. In agreement with earlier ex-situ SEM studies , the etching is shown to proceed in two stages, i.e., ’primary (or bulk) dealloying’ and ’secondary (or ligament) dealloying’.
The high achievable specific surface area up to 30 m²/g, also makes the dealloying process an ideal method for the preparation of nanostructures with electrochemically tunable properties, following the concept of Gleiter et al . By electrochemical ad-/desorption, which strongly influences interfacial charge carrier scattering, reversible resistance variations up to several tens of percents can be generated . This tunability exceeds that of porous nanophase platiunum prepared by compaction of Pt nanopowder  by an order of magnitude, which can be attributed to the extraordinarily high surface-to-volume ratio of dealloyed metals.
 J. Erlebacher et al., Nature 410 (2001) 450
 X. Ye et al., J. Electrochem. Soc, 161 (2014) C517
 H. Gleiter et al., Acta Mater. 49 (2001) 737
 E.-M. Steyskal et al., Langmuir 32 (2016) 7757
 E.-M. Steyskal et al., Beilstein J. Nanotechnol. 4 (2013) 394
|Period||18 Sep 2017|
|Event title||European Congress and Exhibition on Advanced Materials and Processes: Euromat 2017|
|Degree of Recognition||International|
Fields of Expertise
- Advanced Materials Science
Project: Research area
Project: Research project