Bimetallic Pd-Bi/C Catalysts Prepared by Grafting of Complexes with O-Donor Ligands

Abstract

Bimetallic carbon-supported PdBi catalysts were prepared by grafting. To do so a soluble complex of bismuth with exchangeable O-donor ligands was selected, and the carbon support was functionalized to increase the number of surface functions. The grafting procedure was carried out by contacting the various supports with solutions of Pd and/or Bi complexes, to allow ligand exchange reactions to take place between the complexes and the surface O-groups. The grafted fragments were then activated into carbon-supported nanoparticles, which were characterized to unravel the impact of grafting experimental variables on the physico-chemical characteristics of the materials obtained. The PdBi/C catalysts were finally tested in the archetypal glucose selective oxidation reaction, to assess the impact of those characteristics on the catalytic performance. It was found that simultaneous grafting gave larger nanoparticles than consecutive grafting, while higher number of stable surface functions allowed to obtain small and nicely distributed bimetallic nanoparticles. However, the surface functions were found to be deleterious for the catalytic activity, and the placement of the Bi promoter with respect to Pd active phase was identified as another key parameter for the activity, with grafting allowing to compare neatly samples where Bi is underneath, above or beside Pd.