Fe/Fe3C Nanoparticles Confined in Graphitic Layers/Carbon Nanotubes as Efficient Oxygen Reduction Reaction Catalysts

Development of fuel cells is greatly hindered by their sluggish oxygen reduction reaction (ORR). Therefore, rational design and cost-effective fabrication of ORR catalysts with high activity and durability are of paramount importance to the commercialization of fuel cells. In this work, we develop one-step synthesis of nitrogen-doped Fe/Fe3C-encapsulated graphitic layers/carbon nanotubes (Fe/Fe3C@NGL-NCNT) for ORR. The interpenetration of the two-dimensional (2D) NGL and the one-dimensional (1D) NCNT conduces to the construction of three-dimensional (3D) network structure. Such heterostructure renders Fe/Fe3C@NGL-NCNT with different catalytically active sites and improved mass transfer. Fuethermore, the inimitable NCNT with winding earthworm-like structure and a small diameter of below 10 nm provides plentiful active defect sites. Consequently, the synergistic effect of unique 1D/2D/3D heterostructure endows Fe/Fe3C@NGL-NCNT catalyst with a superior activity and durability compared to commercial Pt/C catalyst. This work provides worthy inspiration for engineering excellent ORR electrocatalysts by integrating 1D/2D/3D materials with different catalytically active conponents into one heterostructure via in situ synthesis.