ORR activity and stability of PtCr/C catalysts in a low temperature/pressure PEM fuel cell: Effect of heat treatment temperature

A series of PtCr/C catalysts was prepared by chemical reduction via the seeding/impregnation technique using sodium borohydride (NaBH4) as the reducing agent and then treated at different temperatures in the range of 500-900 °C under a N2 atmosphere for 2 h at ambient pressure. The effect of heat treatment on the catalyst morphology, oxygen reduction reaction activity and stability in a low temperature/pressure proton exchange membrane (PEM) fuel cell was explored. Increasing the heat treatment temperature within this range increased the degree of alloying, particle sizes, Cr content and in-plane conductivity, but diminished the catalyst dispersion and the electrochemical surface area of all the PtCr/C catalysts. Among all the prepared PtCr/C catalysts, that heat-treated catalyst at 500 °C (PtCr/C-500) was the most promising catalyst for the ORR in a PEM fuel cell under a H2/O2 environment, considered in terms of the catalytic activity and stability.