RRDE Study of ORR Kinetics on a Pd3Fe/C Electrocatalyst Annealed at Elevated Temperatures

Carbon-supported Pd3Fe, annealed to 800 degrees C, was synthesized and evaluated using a rotating ring disk electrode to probe oxygen reduction reaction kinetics and mechanism. Ring currents were measured at various disk potentials and at different rotation rates. Disk-to-ring current ratio was found to be different at lower rotation rates for various disk potentials and these results indicated oxygen reduction and hydrogen peroxide generation on Pd3Fe/C surface followed parallel reaction pathway. Extent of hydrogen peroxide generation on Pd3Fe/C surface was also compared to that of Pt/C and Pd/C. Diffusion corrected tafel plots were constructed for overpotentials up to 200 mV. Calculated tafel slope implies that the chemical step following the first electron transfer step is the rate-determining step.