Nitrogen-doped carbon (CNx) nanotubes were synthesized by thermal decomposition of ferrocene/ethy-lenediamine mixture at 600-900 °C. The effect of the temperature on the growth and structure of CNx nanotubes was studied by transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. With increasing growth temperature, the total nitrogen content of CNx nanotubes was decreased from 8.93 to 6.01 at.%. The N configurations were changed from pyr-rolic-N to quaternary-N when increasing the temperature. Examination of the catalytic activities of the nanotubes for oxygen reduction reaction by rotating disk electrode measurements and single-cell tests shows that the onset potential for oxygen reduction in 0.5 M H2SO4 of the most effective catalyst (CNx nanotubes synthesized at 900 °C) was 0.83 V versus the normal hydrogen electrode. A current density of 0.07 A cm-2 at 0.6 V was obtained in an H 2/O2 proton-exchange membrane fuel cell at a cathode catalyst loading of 2 mg cm-2.
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Acknowledgments This work was supported by a National Research Foundation of Korea Grant (NRF-2009-C1AAA001-2009-00926) funded by the Korean government (Ministry of Education, Science and Technology) and by Economy and Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant (No. 20104010100500) funded by the Korean government (Ministry of Knowledge Economy).
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Materials Chemistry