Urea-treated carbon nanofibers as efficient catalytic materials for oxygen reduction reaction

Nitrogen-doped carbon nanofibers (NCNFs) are prepared by the thermal treatment of carbon nanofibers (CNFs) using urea as nitrogen source. Scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy have been employed to characterize the morphology and composition of CNFs and NCNFs. Compared with CNFs, NCNFs display thinner diameter, rougher surface and higher content of pyrrolic-N. As a metal-free catalyst for ORR, NCNFs exhibit comparable catalytic activity, significantly enhanced long-time stability and selectivity in comparison with commercial available Pt/C catalyst. Importantly, the self-supported NCNFs films could be conveniently utilized for electrode modification which is attractive in fuel cells. This work offers a promising metal-free catalyst as an alternative for Pt/C catalyst.