Topological perturbation to a standard dehydrogenation catalyst, Pt3Sn

Abstract

Topological materials, which exhibit protected topological surface states (TSS) nearthe Fermi level, have been proposed to be good catalysts. Topological catalysis may bemore prevalent than we suspect, and not limited to exotic new materials. Here we studya known dehydrogenation catalyst, Pt₃Sn alloy, which happens to be a topologicalsemimetal, and probe the participation of TSSs in catalytic dehydrogenation of methanecatalyzed by this material. Through first principle modeling and detailed analysis ofthe electronic structure for topological and non-topological surfaces of Pt3Sn, we findthat TSS get significantly altered by the binding of reaction intermediates, particularlyH. However, this effect of TSS on the binding of the reagents is merely perturbative,as the majority of the adsorbate binding is achieved by not-surface-focused electronicstates, located much deeper below the Fermi level. Therefore, the reaction energeticsand selectivity are predominantly determined by electronic states other than TSS.The fact that TSS are available for the reagent binding does not alone guaranteethat the catalysis is strongly driven by TSS. However, TSS are not to be ignored, assmall changes in the energetics along the reaction profile can translate into substantialdifferences in the reaction rate. Hence, in our view, Pt₃Sn - a topological material- is first and foremost a standard catalyst, with added topological features, and notpurely a topological catalyst. Our results point at the need to carefully consider allthe bonding effects at the topological material interface.