Composition-dependent catalytic activity of bimetallic PtPd dendrimer-encapsulated nanoparticles having an average size of 1.7 nm for hydrolytic dehydrogenation of ammonia borane

We investigated composition-dependent catalytic activity of bimetallic PtPd dendrimer-encapsulated nanoparticles (DENs) that had a uniform size of similar to 1.7nm for hydrolytic dehydrogenation of ammonia borane (AB). The PtPd DENs, composed of seven different Pt: Pd ratios, were synthesized using hydroxyl-terminated sixth-generation polyamidoamine dendrimers as a molecular template. The dendrimer-templating method allowed for synthesizing bimetallic PtPd DENs with controllable nanoparticle composition while fixing the size of the nanoparticles uniformly at similar to 1.7 nm. Compared with monometallic Pt and Pd DENs, the bimetallic PtPd DENs showed superior catalytic activity for the hydrolytic dehydrogenation of AB. Furthermore, the bimetallic PtPd DENs exhibited composition-dependent activity with the maximum activity (i.e., average turnover frequency=108.5 +/- 15.9mol(H2)center dot mol(atom Pt+)pd-1 center dot min(-1)) at a Pt: Pd ratio of 1:1 for the catalytic hydrolysis of AB.