Revisiting ?-alumina surface models through the topotactic transformation of boehmite surfaces

The rational understanding of ?-alumina (?-Al2O3) supported catalysts requires an ever more improved atomic scale determination the support’s surface properties. By using density functional theory (DFT) calculations, we show how structural and energetic properties alumina crystallites intrinsically depend on its synthesis pathway. Considering case study topotactic transformation boehmite (?-AlOOH) into ?-Al2O3 taking place during calcination, propose a methodology to mimic this pathway by reconstructing relevant slabs following 3 steps: dehydration, contraction/translation Al migration spinel or non-spinel sites. On one hand, confirm reliability some earlier 100, 110 111 structures determined standard bulk cleavage approach. Moreover, find new surfaces harboring Brønsted acid sites (BAS) Lewis (LAS) with specific local structures. More strikingly, that basal 110b inherited from (0 1 0) boehmite, exhibits larger number isolated µ2-OH groups than lateral 110l surface. For (respectively 111) orientation, four three) thermodynamically competing are identified, including models proposed. These results induced finite size morphology effects crystallites. Thanks thorough comparative analysis nature BAS LAS as function thermal treatment water pressure for each surface, identify coherent chemical families across main crystallographic orientations. features open door better differentiation reactivity ones.