Influence of metal precursors on the catalytic activity and structure of non-precious metal electrocatalysts for oxygen reduction reaction

The influence of 3d transition metal precursors has been studied to prepare non-precious metal catalysts (MTETA/C) for the oxygen reduction reaction (ORR) in acid electrolyte. All these 3d transition metal precursors are chelated with triethylenetetramine (TETA) and supported on BP 2000, then pyrolyzed at 800 °C in the presence of Ar. The catalysts are characterized in terms of structure and catalytic activity by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques. Variations of the electrocatalytic activity of these non-precious metal catalysts indicate that the metal precursors have obvious effects on the catalytic activity and this may be related to the N atoms and O species on the carbon surface indicated by XPS. Here, metal chloride is beneficial to prepare these catalysts for the ORR in acidic electrolyte. Furthermore, pyridinic N and pyrrolic N on the carbon surface facilitate the reduction of oxygen on these Fe-based and Co-based catalysts, respectively.