6533b834fe1ef96bd129d4f5
RESEARCH PRODUCT
Measuring electrostatic double-layer forces on HOPG at high surface potentials
Hans-jürgen ButtAstrid Döppenschmidtsubject
Kelvin probe force microscopeAuxiliary electrodeColloid and Surface ChemistryMaterials scienceWorking electrodeHighly oriented pyrolytic graphiteChemical physicsElectrostatic force microscopeSurface forceDLVO theoryAtomic physicsDouble layer forcesdescription
Abstract The aim of this study was to investigate surface forces in aqueous electrolyte solutions between surfaces with high electric potentials. Therefore the force between a surface of highly oriented pyrolytic graphite (HOPG) and a silicon nitride tip of an atomic force microscope was measured. Various electric potentials by a counter electrode were applied to the HOPG, which served as working electrode. As predicted by the Poisson–Boltzmann theory the electrostatic double-layer force changed only in a narrow potential range of ≈300 mV. At high negative sample potentials, where the negatively charged tip was repelled from the sample, the force saturated. At positive potentials an attractive force with a decay length longer than the Debye-length was observed. These observations agree with results of previous experiments with gold and platinum samples. Hence, the effect observed with the hydrophobic HOPG seems to be relatively universal and is not restricted to noble metals.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1999-04-01 | Colloids and Surfaces A: Physicochemical and Engineering Aspects |