The complex energy landscape of quasicrystalline approximant surfaces: application to catalysis
Résumé
Aluminum-based quasicrystals and their approximants present complex crystalline structures, based on giant unit cells containing an ordered arrangement of several hundreds to an infnite number of atoms in the unit cell. These specifc bulk structure leads to complex energy landscapes at the surface, that can be used to grow self-organized molecular flms with long-range quasiperiodic order [1] or to better tailor reacion selecivity and reacivity in catalysis.
Heterogeneous catalysis on such compounds contributed to innovaive breakthroughs in recent years. A few examples show the possible replacement of noble metal-based materials with noble metal-free complex intermetallics for selecive hydrogenaion reacions [2-4]. In this presentaion, I will focus on the selecive semi-hydrogenaion of acetylene on Al13Co4(100). The dissociaion of the H2 molecule is the key process in this case, since the surface terminaion does not contain protruding Co atoms, according to a combinaion of surface science studies and ab iniio calculaions. However, compared to the pure Al(100) and Al(111) surfaces, H2 dissociaion on o-Al13Co4(100) proceeds much easier, due to the presence of surface Co atoms slightly below the mean posiion of the terminaion plane. A possible mechanism for the hydrogenaion is presented, highlighing the selecivity of the reacion on
this Al-rich surface [5].
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