Nitrogen doped carbon nanotubes and their impact on the oxygen reduction reaction in fuel cells

Nitrogen doped carbon nanotubes (N-CNTs) with different nitrogen contents were synthesized as non-precious catalysts for oxygen reduction reaction (ORR) through varying the relative amount of pyridine and ethanol in the stock solution. The structural and chemical properties of the N-CNTs were investigated using scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The characterizations indicated that an increase in the pyridine to ethanol ratio of the stock solution produced N-CNTs with higher nitrogen contents. The electrocatalytic activity of N-CNTs towards ORR in alkaline conditions was evaluated using rotating ring disc electrode voltammetry which showed a positive correlation between nitrogen content and ORR activities. By combining the results of ORR activity and material characterization, it is concluded that an increase in the nitrogen content of N-CNTs can effectively improve the ORR activities.