Fine-tuned coordination environment of Pt-Fe-Pt active site for selective heterogeneous hydrogenation of crotonaldehyde

Abstract

Dispersing the catalytically more active noble metal at the single-site scale ensures maximum atom efficiency for selective heterogeneous hydrogenation over bimetallic particles. However, the low density and random location of the noble-metal atoms compromise the intrinsic activity and/or selectivity because of the resulting altered electronic structure. Here, we report that densely populating and precisely arranging Pt atoms in the form of a Pt-Fe-Pt heterotrimer not only catalyzes preferential hydrogenation of the C=O bond in crotonaldehyde (CAL) but also increases the reaction rate by 35-fold, circumventing the activity-selectivity trade-off. The Pt-Fe-Pt active site is fabricated by H₂ reduction at 673 K of a Pt-Fe₂O₃ particle pair, wherein a 3.3 nm Pt particle sits on a 9.8 nm Fe₂O₃ particle. It interacts with the CAL molecule in a site-bond recognition manner: the left-end Pt atom anchors the C=C bond, whereas the central Fe atom activates the C=O bond, which is further hydrogenated by H atoms adsorbed on the right-end Pt atom.