Synthesis of a carbon nanotube and carbon sphere coexisting catalyst for enhanced oxygen reduction reaction and its applications

Fe and N co-doped carbon nanocomposites exhibit great potential as low-cost and highly active non-precious metal catalysts for the oxygen reduction reaction (ORR). In this study, a method is demonstrated for synthesizing polymer nanospheres, which are subsequently carbonized and functionalized by anchoring Fe[sbnd]N complexes onto the carbon matrix to fabricate a composite catalyst. Characterization reveals that the as-prepared material consists of carbon nanotubes (CNTs) intricately interwoven with carbon nanospheres (CNSs) (denoted as Fe–N–CNT/CNS). Moreover, it is demonstrated that trace amounts of Fe nanoparticles can serve as active sites to significantly enhance the electrocatalytic activity. The composite catalyst with the unique structure achieves a very high specific surface area of 1790 m²/g, providing more active sites to enhance the ORR activity for application in both acidic and alkaline environment. The half-wave potential of the composite catalyst reaches 0.79 V and 0.925 V under the acidic and alkaline conditions, respectively.