A Highly Efficient Electrocatalyst Derived from Polyaniline@CNTs−SPS for the Oxygen Reduction Reaction

It is of vital importance to develop novel, low-cost, and high-efficiency electrocatalysts for the oxygen reduction reaction (ORR), which have a considerable impact on electrochemical energy conversion and storage devices, such as fuel cells and metal−air batteries. In this work, we demonstrate highly active nitrogen-doped carbons with uniform hierarchical structures through sulfonated polystyrene (SPS), regulating the distribution of the PANI covering on carbon nanotubes (CNTs), prepared by using a reliable and controllable route. The as-prepared electrocatalyst shows outstanding activity towards the ORR in alkaline media, manifesting comparable or even better performance compared to commercial Pt/C. The optimized nitrogen-doped CNTs exhibit an onset potential (E_onset) of 0.94 V (vs. reversible hydrogen electrode (RHE)) and half-wave potential (E_1/2) of 0.83 V (vs. RHE) in 0.1 M KOH with superior stability, durability, and methanol tolerance, suggesting their promising applications in fuel cells and metal−air batteries. The significantly improved electrochemical properties demonstrate that the unique SPS layer anchoring on the surface of CNTs in the as-designed PANI@CNTs-SPS contributes to a uniform distribution of nitrogen sites throughout the catalyst.