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Acidic and basic properties of hydroxylated metal oxide surfaces
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1971
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Materials ScienceInorganic ChemistryHydroxyl GroupsEngineeringSurface ChemistryCorrosionNatural SciencesSurface ScienceOxidation ResistanceOxide ElectronicsOh GroupsTotal Oh ContentCatalysisRedox ChemistryChemistryInterfacial ChemistrySurface ReactivityBasic Properties
Hydroxyl groups on metal oxide surfaces exhibit amphoteric behavior. The study aims to explain this amphoteric behavior by examining the structure of the hydroxylated surface. The authors employ a series of reactions to quantify total hydroxyl content and distinguish acidic from basic groups. Experiments on anatase, rutile, η‑alumina, α‑Fe₂O₃, CeO₂, and SnO₂ reveal that about half of the surface hydroxyls are acidic, the remainder mainly basic and exchangeable, with acidity/basicity varying by oxide type.
Hydroxyl groups on the surface of metal oxides are amphoteric in character. From experiments with anatase, rutile, η-alumina, α-Fe2O3,CeO2, and SnO2, half the OH groups are acidic in character, the other half are mainly basic and may be exchanged for other anions. This behaviour is explained by the structure of the hydroxylated surface. Acidity and basicity depend on the nature of the oxide. Several reactions are described for the determination of total OH content as well as the quantities of acidic and basic OH groups.