| AVS 64th International Symposium & Exhibition | |
| Fundamental Discoveries in Heterogeneous Catalysis Focus Topic | Thursday Sessions |
| Session HC-ThP |
| Session: | Fundamental Discoveries in Heterogeneous Catalysis Poster Session |
| Presenter: | Megan Bornstein, University of Utah |
| Authors: | M.F. Bornstein, University of Utah A. Quast, University of Utah R. Park, University of Utah J. Shumaker-Parry, University of Utah I. Zharov, University of Utah |
| Correspondent: | Click to Email |
Supported palladium nanoparticles (PdNPs) have been found to be active catalysts for a variety of organic transformations, with more recent reports showing PdNPs can catalyze chemoselective hydrogenation, as well as the photocatalytic activity of PdNPs can be enhanced plasmonically. Having a method to reliably synthesize small PdNPs on inorganic supports is useful, and we will report on the formation of PdNPs on silica nanospheres in organic solvents, which can be used as a convenient method of PdNPs preparation.
While attempting to immobilize Pd2+ ions on ligand-modified silica nanospheres, we observed the formation of small (~5 nm) uniform PdNPs. The only reactants in this process were surface-functionalized silica spheres, Pd(OAc)2, and reagent-grade acetone. This suggests that an impurity in the acetone is responsible for the reduction of Pd2+ to Pd0. We obtained similar PdNPs when using high purity acetone containing a small amount of added ethanol, while no PdNPs formation was observed in acetonitrile. Thus, this suggests that PdNPs is due to the presence of reducing organic compounds, such as alcohols.
The oxidation state of palladium was confirmed using X-ray photoelectron spectroscopy (XPS), and the morphology of the particles was analyzed using Scanning Transmission Electron Microscopy (STEM). The PdNPs formed were very small, typically around 5 nm in diameter when the reaction was done at room temperature, and uniformly distributed on the surface of a silica support that had been functionalized with primary amines or BiPy ligands, which provide stabilization for the PdNPs. For reactions run at 40 °C, the average diameter of the PdNPs was larger than those run at -77 °C or room temperature. The materials synthesized were capable of catalyzing the reduction of 4-nitrophenol to 4-aminophenol and the oxidation of benzyl alcohol to benzaldehyde.