Insight into the Effects of Pd Single-atom Particles in the Activation of the Carbon-Chloride Bond

Abstract

Palladium (Pd) shows high activity in a variety of catalysis reactions that refer to the activation of the carbon-halogenation bond, and single-atom Pd catalysts have received significant attention as new technology. Nevertheless, there is a huge knowledge gap regarding which Pd sites could form highly reactive centers. It is unclear whether single-atom Pd sites are active in this process or not. In this study, we synthesized Pd/TiO2 nanosheets with Pd loadings of 1%, 5%, and 10% and designed single atom Pd sites and Pd nanoparticles on similar substrates. A scanning transmission electron microscope was used to characterize the synthesized Pd catalysts. As a catalyst, Pd/TiO2 featuring Pd NPs showed high activity in activating the carbon-halogen bond in the activation of carbon-chloride bond, whereas Pd/TiO2 with single Pd atoms showed very low activity in this pros. Accordingly, our results demonstrate that the activation of carbon-halogen bonds cannot be catalyzed by the single-atom Pd sites and emphasize the significance of the ensemble effect in determining the activity of Pd sites.