Pt-free Electrocatalysts for the Oxygen Reduction Reaction

Oxygen reduction reaction (ORR) is one of the most important processes for polymer electrolyte membrane fuel cells (PEMFCs) and direct alcohol fuel cells (DAFCs) as well as for metal-air batteries application. Nowadays, the commercialization of these devices is hindered by the high cost of the components. Alternative Pt-free electro-catalysts, such as Pd/C or Pd-Co/C alloys, were synthesised and characterized for the ORR and tested at the cathode of a direct methanol fuel cell (DMFC). Pd-based electrodes represent a reliable way to minimize the cost in low temperature fuel cells, providing a higher performance than that of Pt-based electrodes at high methanol concentration. In order to employ earthly abundant compounds, in-house non-Pt-group ternary compounds (FeNC or CoNC) have been synthesised and studied as a function of variable heat treatments. Physico-chemical analyses were performed by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-Visible measurements. Electrochemical tests have been carried out to investigate the activity and durability of the electro-catalysts for the ORR. It appears that FeNC treated at 800°C is the most active non-Pt-group electrocatalyst, thus showing promising characteristics for PEMFCs and DAFCs.