Fe/N decorated mulberry-like hollow mesoporous carbon fibers as efficient electrocatalysts for oxygen reduction reaction

Developing oxygen reduction reaction (ORR) catalysts with high performance at low cost is critical for the practical application of fuel cell technology. In this work, novel Fe-N-C hybrid mulberry-like fibers (denoted as MB-CFs), which are composed of hollow mesoporous carbon spheres (HMCSs) encapsulated in N-doped carbon fiber, have been synthesized by a facile electrospinning method. These composite materials have successfully combined together the merits of HMCSs (i.e. high surface area and micro-meso-macropores) and carbon fibers (i.e. large aspect ratio, high conductivity, and favorable flexibility), as well as graphitic and multilevel structure, which are highly desired as ORR catalysts. The electrochemical measurements demonstrate that the designed MB-CFs-0.6 was the best among the series, which possess outstanding activity, excellent durability and selectivity toward ORR catalytic reaction in both alkaline and acid media. Considering the favorable structure and ORR performance of this novel carbon fiber, other nanoparticles (heteroatom or metal-doped hierarchical porous carbon spheres, hollow metal oxides, etc.) could also be electrospun into functional carbon fibers for energy storage and conversion.