Effect of the preparation conditions of carbon-supported Pt catalyst on PEMFC performance

Carbon-supported Pt catalysts were prepared using NaBH4 as a reducing agent in either ethylene glycol or water for use as a cathode catalyst in PEMFCs (polymer electrolyte membrane fuel cells). Aqueous NaBH4 solution was used to reduce Pt precursor and to produce the Pt-W catalyst, while Pt-E and Pt-E-base catalysts were synthesized using NaBH4 in ethylene glycol for the reduction of Pt. Compared to Pt-W catalyst, Pt-E and Pt-E-base catalysts have higher Pt dispersion and larger EAS (electrochemically active surface area) due to the stabilizing effect of ethylene glycolic NaBH4 solution on Pt particles. In addition, increasing pH of the preparation solution improved the Pt dispersion (Pt-E-base). In unit cell tests the performance of Pt catalysts decreased in the following order: Pt-E-base > Pt-E > Pt-commercial > Pt-W. Higher metal dispersion and larger EAS are believed to be responsible for the superior performance of Pt-E catalysts, particularly Pt-E-base, compared to other catalysts.