Highly active N-doped-CNTs grafted on Fe/C prepared by pyrolysis of dicyandiamide on Fe2O3/C for electrochemical oxygen reduction reaction

Non-noble electro-catalysts were synthesized by pyrolyzing dicyandiamide (DCDA) on carbon supported iron oxide at 700 °C, 800 °C and 900 °C. The effects of pyrolysis temperature on electrochemical properties towards oxygen reduction reaction (ORR) were investigated. After pyrolysis, newly generated carbon arising from DCDA was observed in all the catalysts. Especially at 900 °C, carbon nanotubes (CNTs) were grown catalyzed by Fe2O3/C. Pyrolysis of DCDA at higher temperatures increased ORR activity significantly. The catalyst exhibiting the best performance towards ORR was Fe2O3/C pyrolyzed with DCDA at 900 °C. EDX and XPS experiments revealed that nitrogen atoms from DCDA were doped into carbon and the amount of doped nitrogen increased with increasing temperature. The reason for high reactivity towards oxygen reduction reaction is due to nitrogen doped CNTs grown on Vulcan carbon support. The reactivity increased as the amount of doped nitrogen increased.

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► N-doped CNTs grafted on carbon Vulcan are synthesized.
► The catalyst shows high activity towards electro-oxygen reduction reaction (ORR).
► Increasing pyrolysis temperature assists the doping of nitrogen into carbon.
► ORR activity is proportional to the amount of nitrogen doped.