Preparation of high-performance PdPt-Pt core-shell catalyst with shortened carbon nanotubes as support

Shortened carbon nanotubes (SCNTs) obtained by ball milling of carbon nanotubes (5-10 pm) with the assistance of ethanol are used as supports for fabrication of core shell structured PdPt@Pt/SCNTs via a successive colloidal reduction approach. The catalysts are characterized by X-ray diffraction (XRD) analysis, Transmission electron microscopy, and X-ray photoelectron spectroscopy. The active particles are found to disperse on the shortened carbon nanotubes with an average particle size of 3.1 nm. PtPd nanoparticles, rather than single Pd nanoparticles, are used as core materials for prevention of possible agglomeration and better dispersion. Using this catalyst, we investigate methanol oxidation reactions (MOR) and oxygen reduction reactions (ORR). The catalysts show excellent activity to anodic MOR, 2.87 times higher than that of commercial Johnson Matthey 40 wt.% Pt/C catalyst. The ratio of forward current I(f)to backward current I-b is as high as 1.41 for the oxidation of methanol relative to that of 0.74 for the commercial Pt/C catalyst, an indication of better CO tolerance of the former. In the ORR, the reaction is found to proceed via an overall four-electron transfer process. (C) 2013 Elsevier B.V. All rights reserved.