Structure–charge relationship – the case of hematite (001)
| Autor: | Florian Johann, Tajana Preočanin, Frank Heberling, Nikola Kallay, Ludger Weisser, Peter J. Eng, Filip Šupljika, Johannes Lützenkirchen |
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| Rok vydání: | 2015 |
| Předmět: |
Surface (mathematics)
Diffraction Chemistry hematite surface complexation electrical interfatial layer surface potential MUSIC model Inorganic chemistry Charge (physics) Electrolyte Hematite Atmosphere Isoelectric point Chemical physics visual_art visual_art.visual_art_medium Reactivity (chemistry) Physical and Theoretical Chemistry |
| Zdroj: | Faraday Discussions. 180:55-79 |
| ISSN: | 1364-5498 1359-6640 |
| Popis: | We present a multidisciplinary study on the hematite (001)–aqueous solution interface, in particular the relationship between surface structure (studiedviasurface diffraction in a humid atmosphere) and the macroscopic charging (studiedviasurface- and zeta-potential measurements in electrolyte solutions as a function of pH). Upon aging in water changes in the surface structure are observed, that are accompanied by drastic changes in the zeta-potential. Surprisingly the surface potential is not accordingly affected. We interpret our results by increasing hydration of the surface with time and enhanced reactivity of singly-coordinated hydroxyl groups that cause the isoelectric point of the surface to shift to values that are reminiscent of those typically reported for hematite particles. In its initial stages after preparation the hematite surface is very flat and only weakly hydrated. Our model links the entailing weak water structure with the observed low isoelectric point reminiscent of hydrophobic surfaces. The absence of an aging effect on the surface potentialvs.pH curves is interpreted as domination of the surface potential by the doubly coordinated hydroxyls, which are present on both surfaces. |
| Databáze: | OpenAIRE |
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