Abstract:
A large number of today's technological processes rely on catalytic reactions to synthesize chemical and pharmaceutical compounds, refine fuels or treat exhaust gases. Developing optimized and efficient catalysts is therefore a key faculty for the reduction of primary materials and energy resources as well as for the reduction of harmful emission to the environment. In recent years, intermetallic compounds, characterized by interatomic bonds of partially ionic and covalent character, have emerged as interesting materials class to look for new catalyst to be used in heterogeneous catalysis. The extensive number of possible binary intermetallic compounds, with electronic and structural properties that can strongly differ from their constituting elements, open a vast field to find catalyst optimized in the properties triangle of activity, selectivity and stability.
In our presentation, we will review the recent developments in the field of intermetallic compounds in heterogeneous catalysis and also review the particularities of the surface terminations of these materials, which arise from multiple, inequivalent atomic planes present for a given crystallographic direction and the partially covalent bond character. We will then turn our attention to the PdGa compound, which has been found to combine high selectivity and activity in acetylene semi-hydrogenation [1]. We will discuss the atomic structure of the low Miller index planes of PdGa and present experimental and theoretical results from the adsorption of small molecules (CO, C2H2 and C2H4) on the (111) and (-1-1-1) PdGa surface, which differ significantly in the local structure of the top most Pd atoms and therefore are model surfaces to study active site isolation and ensemble effects on catalyst selectivity [2]. In the last part, we will explore the possibilities of chiral selective adsorption on these surfaces made possible by the intrinsic chiral nature of the P213 space group PdGa belongs to [3].
[1] M. Armbruster, M. Kovnir, M. Behrens, D. Teschner, Y Grin, and R. Schlogl, JACS 132, 14745 (2010)
[2] J. Prinz, C. A. Pignedoli, Q. S. Stockl, M. Armbruster, H. Brune, O. Groning, R. Widmer, D. Passerone
JACS 136, 11792 (2014).
[3] J. Prinz, O. Groning, H. Brune, and R. Widmer, Angew.Chem. 127,3974 (2015)
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