Preparation and Characterization of Pt/C Cathode Catalysts for Direct Methanol Fuel Cells Effect of Different Preparation and Treatment Methods

The carbon-supported platinum catalysts 20% Pt/C were prepared by reduction of platinum salts with various reducing agents (such as NaBH4, HCHO and EG(ethylene glycol)) in various solvents (such as H2O, i-PrOH and EG). The Pt/C(EG) catalyst was treated at 900 degreesC in hydrogen atmosphere. The distribution and size of Pt metal particles in the Pt/C catalysts were characterized by XRD and TEM. The Pt metal particles of Pt/C(EG) catalyst are highly and homogeneously dispersed with a narrow size distribution, centering at 2.4 nm. The rotating disk electrode (RDE) tests showed that the activity order of the catalysts for orygen redutive reaction (ORR) is as follows: Pt/C(HCHO) > Pt/C(EG) > Pt/C(NaBH4). However, the Pt/C(EG) catalyst exhibits enhanced activity for ORR and superior performance in direct methanol fuel cell test as compared with the Pt/C catalysts prepared by the other two methods and the heat-treated Pt/C, which could have smaller Pt particle size. Pt/C(EG) catalyst showed better performance at activation-controlled region and comparative power density as compared with the commercial Pt/C catalyst. Cl- shows a negative effect on the ORR in both DMFC and RDE tests.