This title appears in the Scientific Report : 2011 
Interface capacitance of nano-patterned electrodes
Ibach, H.
Beltramo, G. L. / Giesen, M.
Biomechanik; IBN-4
Surface science, 605 (2011)
Amsterdam Elsevier 2011
10.1016/j.susc.2010.10.025
Journal Article
BioSoft: Makromolekulare Systeme und biologische Informationsverarbeitung
Surface Science 605
J
Metal-electrolyte interface
Nano-structured surfaces
Dielectric properties
Please use the identifier: http://dx.doi.org/10.1016/j.susc.2010.10.025 in citations.


By employing numerical solutions of the Poisson-Boltzmann equation we have studied the interface capacitance of flat electrodes with stripes of different potentials of zero charge phi(pzc). The results depend on the ratio of the width of the stripes l to the dielectric screening length in the electrolyte, the Debye length d(Debye), as well as on the difference Delta phi(pzc), in relation k(B)T/e. As expected, the capacitance of a striped surface has its minimum at the mean potential of the surface if l/d(Debye)<< 1 and displays two minima if l/d(Debye)>> 1. An unexpected result is that for Delta phi(pzc)congruent to 0.2V, the transition between the two extreme cases does not occur when l congruent to d(Debye). but rather when l>10d(Debye). As a consequence, a single minimum in the capacitance is observed for dilute electrolytes even for 100 nm wide stripes. The capacitance at the minimum is however higher than for homogeneous surfaces. Furthermore, the potential at the minimum deviates significantly from the potential of zero mean charge on the surface if l>3d(Debye) and Delta phi(pzc) is larger than about 4k(B)T/e. The capacitance of stepped, partially reconstructed Au(11n) surfaces is discussed as an example. Consequences for Parsons-Zobel-plots of the capacitances of inhomogeneous surfaces are likewise discussed. (C) 2010 Elsevier B.V. All rights reserved.