Small and uniform Pd monometallic/bimetallic nanoparticles decorated on multi-walled carbon nanotubes for efficient reduction of 4-nitrophenol

Pd and PdAu nanoparticles stabilized on multi-walled carbon nanotubes are synthesized by simple metal sputtering onto nanotubes dispersed in ionic liquids. The nanoparticles are as small as about 2 nm and possess bare surface without capping agents. The surface density of the nanoparticles can be controlled by tuning the sputtering conditions, while the sizes of the nanoparticles remain very similar. The supported Pd/PdAu nanoparticles are highly catalytically active for reduction of 4-nitrophenol, and an activity factor up to 205 s−1 g−1 is achieved. The PdAu bimetallic nanoparticles show superior catalytic performance than the Pd monometallic counterparts, indicating the synergistic effects of Pd and Au. The present approach has the merit of making alloyed nanocatalysts as simple as making corresponding elementary ones.