The effect of heat treatment on nanoparticle size and ORR activity for carbon-supported Pd–Co alloy electrocatalysts

Carbon-supported Pd–Co alloy electrocatalysts were synthesized and characterized for the purpose of the fuel cell cathode oxygen reduction reaction (ORR). An impregnation method was employed for the synthesis, in which sodium borohydride was used as a reducing agent. The synthesized catalysts were characterized in terms of structural morphology and catalytic activity by XRD, XPS and electrochemical measurements. Surface cyclic voltammetry was used to confirm the formation of the Pd–Co alloy. In order to improve activity and stability, the catalysts were heat-treated in the temperature range of 300 °C to 700 °C. The optimal heat-treatment temperature was found to be 300 °C, where the average particle size of 8.9 nm, and the highest ORR catalytic activity, were obtained. The catalyzed ORR kinetics were also studied using the rotating disk electrode (RDE) method. The kinetic parameters were then obtained. Electrocatalytic ORR activity was also examined in an acidic solution containing methanol. The results showed that the synthesized Pd–Co/C catalyst has methanol tolerant capabilities.