Self-Sacrificial Template Synthesis of a Nitrogen-Doped Microstructured Carbon Tube as Electrocatalyst for Oxygen Reduction

The development of low-cost, efficient and stable electrocatalysts for the oxygen reduction reaction (ORR) is desirable but remains a great challenge. We report a self-sacrificial template synthesis approach for nitrogen-doped hollow carbon microtubes as electrocatalyst for ORR. Typically, Fe-MIL (Materiaux de l'Institute Lavosier) nanocrystals cast as self-sacrificial template. Polyaniline (PANI) was in situ-synthesized and deposited on the surface of Fe-MIL nanocrystals. By a two-step pyrolysis of the MIL-101 (Fe)@PANI hybrids, unique microstructured carbon tubes with Fe3O4 nanoparticles encapsulated inside the wall were fabricated after the self-sacrificial template decomposed. The optimized C-PANI-MIL-2 catalyst exhibits a high onset potential of 1.0 V in alkaline media. Out of the negative effect of the disruption of metal-organic frameworks (MOF) morphology, the ingenious catalytic activities may be ascribed to the well-defined microtube architecture with a high accessible surface area, the existence of FeN2+2/FeN4 and rich active nitrogen atoms. Moreover, C-PANI-MIL-2 exhibited excellent methanol tolerance and durability compared to a commercial Pt/C catalyst in both electrolytes. This work may provide a new strategy for the design and preparation of microstructured non-precious metal based catalysts supported on hollow carbon tubes for fuel cells.