Double-Walled Carbon Nanotubes as Catalyst Support in Direct Methanol Fuel Cells

Double-walled carbon nanotubes (DWCNTs) with a large specific surface area, good crystallization, and netlike structure were synthesized by chemical vapor deposition. The DWCNT-supported platinum catalyst was prepared by a modified polyol method and used as a cathode catalyst for the oxygen reduction reaction (ORR) in direct methanol fuel cells. The Pt/DWCNT catalyst was characterized by X-ray diffraction, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry, and a single cell test. The TEM images showed that platinum particles with an average size of 2 - 3 nm were uniformly distributed on the surface of the DWCNTs when the platinum loading is as high as 60 wt %. The Pt binding energy of XPS showed a stronger interaction between Pt particles and DWCNTs than between Pt particles and Vulcan XC72R, and the Pt/DWCNT catalyst exhibited better activity and stability toward ORR than a commercial Pt/XC72R catalyst under identical conditions. This can be attributed to the unique properties of the DWCNTs, which can facilitate electron transfer, water removal, and oxygen access to the catalyst active sites. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3463724] All rights reserved.