Synthesis and catalysis of polymer-protected Pd/Ag/Rh trimetallic nanoparticles with a core-shell structure

Colloidal dispersions of polymer-protected Pd/Ag/Rh trimetallic nanoparticles were synthesized via self-organization by mixing colloidal dispersions of polymer-protected Rh nanoparticles with those of polymer-protected Pd/Ag bimetallic nanoparticles with a core-shell (Pd-core/Ag-shell) structure, which were prepared in advance by a sacrificial hydrogen-reduction method. The Pd/Ag/Rh trimetallic nanoparticles appeared to have a triple core-shell (Pd-core/ Ag-interlayer/Rh-shell) structure on the basis of UV-vis absorption spectra, FT-IR spectra of adsorbed CO, TEM, HR-TEM, and EF-TEM observation. The spontaneously formed trimetallic nanoparticles having an atomic composition of Pd/Ag/Rh = 1/2/13.5 and an average diameter of 2.2 nm showed the highest catalytic activity among the metal nanoparticle catalysts tested here for hydrogenation of methyl acrylate at 30 degrees C under atmosphere of hydrogen.