Electrocatalytic properties of hybrid palladium–gold/multi‐walled carbon nanotube materials in fuel cell applications

Multi-walled carbon nanotubes (MWCNTs) supported Pd-Au nanoparticles for electrooxidation of formic acid (FA) are prepared and compared with Pd/MWCNTs in this study. The nanocatalysts are prepared by a polyol method, and characterized using X-ray diffraction (XRD), thermogravimetry (TGA), SEM, and field emission transmission electron microscope (FE-TEM). Cyclic voltammetry (CV) is used to examine the catalytic activity towards FA electrooxidation. Controlling the contents of the precursors (PdCl2 and HAuCl4 center dot 4H(2)O), the different weight ratios of Pd-Au can be synthesized to form the various solid solution structures of Pd-Au. TEM image results indicate the average diameter of Pd-Au solid solution particles is about 10-30 nm. The results of electrochemical analysis show that the Au (10 wt.%)/[Pd/MWCNTs (1:9)](90 wt.%) hybrid catalysts exhibit the highest catalytic activity and better stability than that of Pd/MWCNTs in FA electrooxidation. The promoting of Pd-based catalyst with Au to form solid solution improves the performance of the catalyst in FA electrooxidation. The newly synthesized electrocatalyst is promising for application in direct formic acid fuel cell (DFAFC). (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim