One-step synthesis of hollow chain-like nitrogen doped carbon nanotubes/iron carbide as highly efficient bifunctional oxygen electrocatalyst

摘要

The design of a new class of bifunctional Fe-N/C electrocatalysts with oxygen reduction reaction (ORR) and oxygen evolution reacton (OER) activity is still a big challenge. In this work, hollow chain-like nitrogen doped carbon nanotubes (NCNTs)/iron carbide (Fe3C) hybrid electrocatalysts (FN-B-800) is prepared by annealing of poly-vinylpyrrolidone (PVP), ferric chloride (FeCl3 center dot 6H(2)O), and melamine mixture. The resulting electrocatalysts shows very high ORR activity with the limiting current density of 5 mA cm(-2) at a speed of 1600 rpm, which is larger than that of Pt/C. Furthermore, half-wave potential (E-1/2) and onset potential of FN-B-800 are close to commercial Pt/C catalyst. Most importantly, the tolerance to fuel cell molecules (e.g., methanol) and the stability of FN-B-800 are surpasses to commercial Pt/C catalysts. Meanwhile, the FN-B-800 also exhibits an excellent OER catalytic performance. The outstanding bifunctional electrocatalytic activities of the FN-B-800 hybrids are attributed to effectively doped N sites and high active Fe-N-x sites, which are synchronously constructed on carbon substrate, leading to enhancing the overall electrochemical performance.