Effect of heat-treatment on the performance of PtM/C (MÂ =Â Cr, Pd, Co) catalysts towards the oxygen reduction reaction in PEM fuel cell

Effect of heat-treatment on the performance of the PtM/C (M = Cr, Pd, Co) catalysts towards the oxygen reduction reaction (ORR) in acid solution and in proton exchange membrane (PEM) fuel cell was explored. Compared with the Pt/C catalyst, the heat-treatment induced the formation of a more crystallite PtM structure and an agglomeration of Pt particles in all PtM catalysts, resulting in a decreased electrochemical surface area (ESA). Besides, the heat-treatment increased the electrical conductivity, which consequently affected the ORR activity and stability of the PtM/C catalyst. Among all prepared PtM/C catalysts, the PtCo/C catalyst exhibited the highest ORR activity, with a current density of around 392.8 mA/cm2 (235.7 mW/cm2) at 0.6 V under a H2/air environment at 60 °C and ambient pressure with the ESA loss of 58.7% after 500 cycles of cyclic voltamogram (CV). Heat-treatment of this catalyst under a N2 atmosphere slightly decreased the ORR activity by 3.41% but significantly increased the stability by ∼17.2%.