Book/Master Thesis

FZJ-2017-02368

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Surface Potential of Metallic Surfaces and Self-Assembling Organic Monolayers in Various Electrolytes

Wang, J. (Corresponding author)FZJ*

2016
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-188-0

Please use a persistent id in citations: http://hdl.handle.net/2128/14145

Abstract: The aim of this thesis is to systematically investigate the ζ potential of different surfaces (polypropylene, borosilicate glass, Pt and Au thin films, and self-assembling monolayer) in different chloride electrolytes XCl (X = Li, Na, or K), focusing on the pH- and concentration-dependent ζ potential and the surface treatment with oxygen. The experiments were performed with a modified “SurPASS Electrokinetic Analyzer” using the streaming potential and streaming current methods. The pH-dependent ζ potential analysis of borosilicate glass, Pt, and Au shows that, Pt possesses the highest ζ potential, followed by borosilicate glass and Au for all chloride electrolytes. The impact of the different electrolytes on the ζ potential is more complex. The oxygen activation of the metallic surfaces seems to lead to the formation of a thin oxide layer, which seems to be less stable for Pt than for Au, whereas we obtained a stable oxygen activation for the oxide borosilicate glass. At large Debye length (i.e. low electrolyte concentration), the ζ potential changes linearly with decreasing Debye length down to a “critical” Debye length. The “critical” Debye length is different for the different surfaces: 0.7 – 0.9 nm for borosilicate glass, 0.5 – 1.2 nm for Pt, and 1.35 – 2 nm for APTES. Below the “critical” Debye length, the ζ potential drops strongly. We explain the unusual and transient streaming current-pressure correlation in this regime by a complex adsorption/desorption process for the ions at the surface. As a result, the classic electrical double layer model has to be modified for high electrolyte concentrations. For organic layers this is even more complex, since several surface contributions arising from the molecules and the carrier have to be taken into account.

Note: RWTH Aachen, Masterarbeit, 2016

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Contributing Institute(s):

1. Bioelektronik (PGI-8)
2. Bioelektronik (ICS-8)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

Appears in the scientific report 2017

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Database coverage:
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