Abstract:
This research was carried out to study the effects of Pt : Cr ratios (1:1 to 5:1) and heat treatment atmosphere (H2 and N2) on the activity and stability of PtxCr/C catalysts for oxygen reduction reaction (ORR) in the proton exchange membrane (PEM) fuel cell. The preliminary results showed that when the Pt : Cr ratio in PtxCr/C catalyst increased, the electrochemical surface area also increased but the degree of alloying decreased, while a heat treatment of PtxCr/C catalyst under H2 and N2 ambient could increase the degree of alloying, but decrease of electrochemical surface area. The ORR activity and stability were tested in acid electrolyte and in PEM fuel cell under H2/O2 and H2/air at 60 oC and atmospheric pressure. It was found that the Pt3Cr/C catalyst had the comparable ORR activity with the Pt4Cr/C catalyst, but it exhibited a better stability in acid electrolyte. With regards to the effect of heat treatment under either H2 or N2, the Pt3Cr/C (N2) catalyst provided the highest ORR activity in acid electrolyte and in PEM fuel cell under H2/O2 and H2/air. It also provided the higher stability in acid solution compared with Pt3Cr/C catalyst.