Electrocatalytic Activity of Fe/N/C Catalyst for the Oxygen Reduction Reaction in Alkaline Electrolyte

Fuel cells have been recognized as one of the most promising power sources due to their high efficiency and low emissions. However, the high cost and scarcity of traditional Pt-based catalyst limit their commercialization. More intensive research have been focused on the development of non-noble-metal catalysts in order to replace Pt for catalyzing oxygen reduction reaction (ORR). Recently, it was reported that the FeN/C catalyst have high activity toward ORR. Chemical vapor deposition (CVD) is the most common method for the preparation of the Fe/N/C catalyst. However, the cost of CVD method is much higher. Here we report a facile method for the preparation of FeN/C catalyst for ORR in alkaline electrolyte. The catalyst is prepared by using graphene oxide as carbon support, and K3Fe(CN)(6) as both nitrogen and iron sources. The precursors are then treated thermally at 800 degrees C under nitrogen atmosphere. In the process of heat treatment, the functional groups of graphene oxide are decomposed to form active center. Simultaneous doping of N and Fe can be realized by the interaction between graphene oxide and K3Fe(CN)(6). The non-noble-metal catalyst is further characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). It shows that N and Fe elements are successively doped into the graphene substrate. In the catalyst, N elements exist mainly in the forms of pyridine N, pyrrole N and graphite N. Fe(II) and Fe(III) are coordinated with pyridine N to form Fe-N-x structure. The electrocatalytic activity of catalyst is evaluated by cyclic voltammetry (CV) and rotating disk electrode (RDE) experiments. The Fe/N/C catalyst shows high electrocatalytic activity toward ORR in an alkaline solution with an onset potential of -0.15 V vs. Ag/AgCl reference electrode. CVs of consecutive sweep for 2000 cycles are conducted to study the stability of the catalyst. The Fe/N/C catalyst exhibits excellent stability and methanol-tolerant ability.