Electrooxidation of hydrogen on nanostructured Pt/C catalysts for polymer electrolyte fuel cells

Abstract

Mesoporous carbon cryogel synthesized by sol-gel polycondensation and freeze-drying with specific surface area (BET) of 517 m(2) g(-1) was used as a catalyst support. Pt/C catalysts were prepared by a modified ethylene glycol method (EG). Transmission electron microscopy (TEM) images show that the dispersion of the catalyst is very uniform with a mean particle size of about 2.65 nm. Hydrogen oxidation reaction (HOR) was studied on Pt/C catalyst in 0.5 mol dm(-3) HClO4 acid solution. It has been found that HOR appears as a reversible two-electron direct discharged reaction (Tafel slope for this reaction is approximate to 30mV dec(-1)) and that Pt/C catalyst exhibits a very high catalytic activity. However, the corresponding value of the exchange current density obtained by dividing the exchange current by the active surface area of Pt particles has the same order of magnitude as those for the HOR in acidic solution at single crystal and polycrystalline Pt.