Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 44: Wetting, Micro- and Nanofluidics
CPP 44.11: Vortrag
Donnerstag, 14. März 2013, 18:15–18:30, H39
Imbibition of electrolytes into nanoporous gold and electrocapillary effects — •Yahui Xue1,2, Jürgen Markmann1,3, Patrick Huber3, Huiling Duan2, and Jörg Weissmüller1,3 — 1Helmholtz-Zentrum Geesthacht, Institut für Werkstoffforschung, Werkstoffmechanik, 21502 Geesthacht, Germany — 2State Key Laboratory for Turbulence and Complex System, Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing 100871, China — 3Technische Universität Hamburg-Harburg, Institut für Werkstoffphysik und -technologie, 21073 Hamburg, Germany
Electrocapillary techniques exhibit great advantages in nonmechanical electrofluidic manipulation, e.g., flow actuation in micro-/nano- channels. One issue of interest is the spontaneous imbibition of fluids in bodies with a nanoscale pores size. Contrary to previous studies we here use a metallic nanoporous body. This allows us to control the electrode potential at the solid-fluid interface. Nanoporous gold (NPG) with uniform pore- and ligament size of ~45 nm was fabricated by dealloying an Ag75Au25 alloy. Spontaneous imbibition of aqueous electrolytes obeys the Lucas-Washburn law. Electrocapillary effects were then used to manipulate the imbibition dynamics. Due to the enhanced wetting, the Washburn law predicts an acceleration of the imbibition by ~60%. Yet, imbibition experiments show only ~25% acceleration. A possible explanation is that the ion transport capability through nanopores limits the charging of the double layer at the invasion front, which is confirmed by potential step coulometry experiments.