Palladium and Palladium Gold Catalysts Supported on MWCNTs for Electrooxidation of Formic Acid

Novel multi-wall carbon nanotubes (MWCNTs) supported Pd-Au catalyst for electrooxidation of formic acid was prepared and compared with a similarly prepared Pd/MWCNTs and with a commercial Pt-Ru/Vulcan catalyst. The catalysts were prepared by a two-stage polyol method, followed by H-2-Ar annealing and were characterised by using X-ray diffraction, FE-TEM and EDX. Cyclic voltammetry (CV) was used to test their catalytic activity towards formic acid electrooxidation and accessible metal surface in the catalyst layer. In the case of the precursor of Pd-Au/MWCNTs catalyst (before H-2-Ar annealing), subsequent deposition of Pd and Au led to a material of the core-shell structure, catalytically inactive. Annealing of the core shell Pd-Au/MWCNTs precursor in H-2-Ar resulted in the formation of the novel Pd-Au/MWCNTs catalyst. A highly dispersed Pd-Au solid solution (average XRD particle size 4.8 nm) is formed, and the novel catalyst is more active than the Pd/MWCNTs one. Both the Pd-Au/MWCNTs and the Pd/MWCNTs catalysts turned out to be more active than a commercial, highly dispersed Pt-Ru/Vulcan catalyst.