Hydroxyl groups on γ-alumina surfaces:: A DFT study

Despite numerous experimental studies devoted to the acid-base properties of gamma-alumina, the precise nature of surface acid sites remains unsolved. Using density functional (DFT) calculations, we propose realistic models of gamma-alumina (110) and (100) surfaces accounting for hydroxylation/dehydroxylation processes induced by temperature effects. The vibrational analysis, based on DFT calculations, leads to an accurate assignment of the OH stretching frequencies observed by infrared (IR) spectroscopy. The extension to chlorinated surfaces, which brings new insights into the understanding of the role of dopes, is also addressed. (C) 2002 Elsevier Science (USA).