PUMA
Istituto dei materiali per l'elettronica ed il magnetismo     
Calzolari A., Corni S., Di Felice R., Cicero G., Catellani A. Gold wettability at the nanoscale. In: SimBioMa - Conference on Molecular Simulations in Biosystems and Material Science (Konstanz (DE), 2 - 5 Aprile 2008).
 
 
Abstract
(English)
The study of fluid interactions with solid surfaces is particularly relevant in a number of fields, ranging from material science and technology, to biology and most recently to nanofluidics. A fundamental field of applications regards the interaction of water with metals, which is of particular relevance to heterogeneous catalysis and electrochemistry and has thus motivated several studies [1-4]. Nowadays, however, a microscopic understanding and characterization of the solid/liquid interaction are still lacking: the first efforts in this direction are mainly based on classical molecular dynamics simulations [5], but basic questions on the binding site and orientation of H2O on metal surfaces remain unanswered. Here, we provide a first-principle description of the interaction between water and a gold surface, within the plane-wave Density Functional Theory (DFT) scheme. We first characterize the water/surface interaction at low coverages, in terms of the electronic and structural properties of the interface. Different mechanisms have been proposed for other noble metals as dominating factors, namely the adsorbate-substrate bonding, and the H bond strength between water molecules, in the presence of the substrate [3, 4, 6]. We then investigate a realistic liquid/solid interface at ambient temperature by means of ab initio molecular dynamic simulations, in order to define the hydrophilic/obic character of the surface. Beyond the characterization of the electronic and structural properties of the interface in vapor and liquid conditions, our study also provides information on the confinement effects on water reorientation, and dynamics. [1] P. A. Thiel and T. E. Madey, Surf. Sci. Rep. 7, 211 (1987), and references therein. [2] M. A. Henderson, Surf. Sci. Rep. 46, 1 (2002). [3] P.J. Feibelmann, Science 295, 99 (2002). [4] A. Michaelides, A. Alavi, D.A. King, Phys. Rev. B 69, 113404 (2004). [5] G. Hummer, J.C. Rasaiah, J.P. Noworyta, Nature 414, 188 (2001); T. Werder, et al., NanoLetters 1, 697 (2001); R.J. Mashl, S. Joseph, N.R. Aluru, E. Jakobsson, NanoLetters 3, 589 (2003). [6] A. Michaelides, V.A. Ranea, P.L. deAndres, D.A. King, Phys. Rev. Lett. 90, 216102 (2003).
Subject DFT scheme


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