Enhanced Methanol Oxidation Activity of PtRu/C100-xMWCNTsx (x=0-100 wt.%) by Controlling the Composition of C-MWCNTs Support

PtRu nanoparticles decorated on carbon-based supports are of great interest for direct methanol fuel cells (DMFCs). In this study, PtRu alloy nanoparticles decorated on carbon Vulcan XC-72 (C), multi-walled carbon nanotubes (MWCNTs), and C-MWCNTs composite supports were synthesized by co-reduction method. As a result, PtRu nanoparticles obtained a small mean size (d(mean) = 1.8-3.8 nm) with a size distribution of 1-7 nm. We found that PtRu/C60MWCNTs40 possesses not only high methanol oxidation activity, but also excellent carbonaceous species tolerance ability, suggesting that C-MWCNTs composite support is better than either C or MWCNTs support. Furthermore, detailed investigation on PtRu/C100-xMWCNTsx (x = 10-50 wt.%) shows that the current density (J(f)), catalyst tolerance ratio (J(f)/J(r)), and electron transfer resistance (R-et) are strongly affected by C-MWCNTs composition. The highest J(f) is obtained for PtRu/C70MWCNTs30, which is considered as an optimal electrocatalyst. Meanwhile, both PtRu/C70MWCNTs30 and PtRu/C60MWCNTs40 exhibit a low R-et of 5.31-6.37 omega center dot cm(2). It is found that C-MWCNTs composite support is better than either C or MWCNTs support in terms of simultaneously achieving the enhanced methanol oxidation activity and good carbonaceous species tolerance.