Catalytic activity of bimetallic nanoparticles M@Pd (M = Ni, Cu, Ag, Pt, Au) in deoxygenation of carboxylic acids: a quantum chemical evaluation

The key intermediates and transition states of the mechanisms of propionic acid decarbonylation and decarboxylation on icosahedral monometallic nanoclusters Pd 55 and bimetallic core—shell nanoparticles M 13 @Pd 42 (M = Ni, Cu, Ag, Pt, Au) were simulated in terms of the density functional theory with the PBE functional. According to calculations, the catalytic activity of the Ag 13 @Pd 42 and Au 13 @Pd 42 particles can be higher than that of Pd 55 particle. The synergistic effect is due to charge transfer from the core atoms to the shell ones (electronic effect), to nonuniform electron density distribution between the surface Pd atoms, and to the formation of Pd 0 —Pd δ− or Pd δδ— —Pd δ− active sites (geometric effect). The presence of these sites is a due to a weakening of the Pd—Pd bonds in the shell of the Ag 13 @Pd 42 and Au 13 @Pd 42 particles. As a consequence, the activation energy of the C—C and C—OH bond dissociation decreases by 4.2–5.6 kcal mol −1 on going from the Pd 55 cluster to the bimetallic nanoparticles.