Preparation of Tethered Palladium Catalysis Supported on Gold(111) and Its Surface Characterization by X-ray Photoelectron Spectroscopy (XPS)

Abstract

Abstract Chelated tethering ligands were confined on a Au(111) substrate, and the confinement of the ligands was confirmed by X-ray photoelectron spectroscopy (XPS). Palladium was anchored to the ligands to construct heterogeneous {Pd}–L–Au(111) catalysts (L = ligand). A {Pd}–Au(111) catalyst was also prepared by adsorbing the Pd complex directly on the Au(111) substrate without a tethering ligand. Both types of catalysts were used in the Mizoroki–Heck reaction to evaluate their catalytic activities. The tether-ligated Pd catalyst {Pd}–L–Au(111) activity decreased with recycling, whereas the {Pd}–Au(111) catalyst was quite stable upon reuse. The surfaces of both catalyst types were evaluated using XPS to determine the presence of tethering ligands and/or Pd on the Au(111). The ligands of the tether-ligated Pd catalysts could not be detected on the Au(111) surface after the Mizoroki–Heck reaction, which suggests weak bonding of the S–Au by which the ligand is bound to the Au(111) substrate.