A facile approach for constructing nitrogen-doped carbon layers over carbon nanotube surface for oxygen reduction reaction

Fabricating nitrogen-doped carbon layers over the conductive substrate is a cost-effective and efficient approach to develop practical oxygen reduction reaction (ORR) catalyst. In the current work, relying on the commercially available carbon nanotube (CNT), nitrogen-doped carbon layers over CNT is constructed by annealing the in situ formed complex over the CNT surface derived from iron ion inducing diaminonaphthalene (DAN) polymerization and DAN self-polymerization. Physical and electrochemical characterizations are carefully conducted to comparatively analyze the structure and activity relationship. The significance of iron in constructing nitrogen-doped carbon layers and tuning active sites of N types over multiwall carbon nanotube for ORR is demonstrated by X-ray photoelectron spectroscopy and Raman scattering spectrum. The excellent performance of nitrogen-doped carbon layers over CNT (catalyzed by iron) towards ORR is displayed by rotating ring-disk electrode. Specifically, the onset potential, half-wave potential, and limiting current density are 0.961 V, 0.831 V, and 5.20 mA cm^?2 respectively, very close to the state-of-the-art commercial Pt/C catalyst. Both high surface area and efficient N active sites should be considered in the nitrogen-doped carbon materials design and fabrication for ORR. Considering the large-scale availability, it has significant value in fuel cells commercial applications.