Electrocatalytic activity of Pt-Pd electrocatalysts for the oxygen reduction reaction in proton exchange membrane fuel cells: Effect of supports

Pt-Pd electrocatalysts supported on different types of support including domestic Hicon Black (HB), multi-walled carbon nanotubes (MWCNT) and titania (TiO2) were prepared by a combined approach of impregnation and seeding, and compared to that prepared using the commercial Vulcan XC-72 (C). Their oxygen reduction reaction (ORR) activities in an acid electrolyte (0.5 M H2SO4) and in a single proton exchange membrane (PEM) fuel cell were evaluated. The type of support was found to affect the Pt-Pd electrocatalyst morphology and ORR activity. The Pt-Pd/C electrocatalyst had the smallest Pt particle size, better catalyst dispersion and a higher Pt:Pd M ratio compared to that of other types of supported Pt-Pd electrocatalysts. However, both in the acid solution and in a single PEM fuel cell, the ORR activities of the Pt-Pd/HB and Pt-Pd/CNT electrocatalysts were comparable to that of the Pt-Pd/C one. The ORR pathway of all supported Pt-Pd electrocatalysts were close to the four-electron pathway.