Atomic origin of CO-Interaction effect of PtPb@Pt catalyst revealed by in situ environmental transmission electron microscopy

The carbon monoxide (CO) interaction effect on active Pt-based catalysts is critical because the surface reconstruction and phase separation behavior of bimetallic catalysts in a CO environment can profoundly impact the catalysts’ activity and durability. However, because direct and dynamic observation has proven elusive, the exact failure mechanisms of the nanocrystal structural modifications induced by CO are poorly understood. In this work, we probe the dynamic structural and compositional transformations of an individual PtPb@Pt nanoplates in a CO gas atmosphere via in-situ environmental transmission electron microscopy (ETEM) and confirmed with theoretical calculations. The interaction of Pt and Pb atoms with CO molecules are revealed dynamically, including the resulting breakdown of the PtPb@Pt nanoplates. The Pt atoms aggregate on surface facets of the original PtPb lattice and the Pt-CO complex mobilizes, cracking the Pt surface layers and stripping Pb atoms from the PtPb alloy core to form Pb(CO) 4 . These interactions provide direct clues for the failure analysis of the catalyst and, thus, represent a critical step towards the design of an anti-CO interaction catalyst.