Metal‐Free Hybrid of Nitrogen‐Doped Nanocarbon@Carbon Networks for Highly Efficient Oxygen Reduction Electrocatalyst

Further improving the oxygen reduction reaction (ORR) catalytic activity of carbon catalysts is highly challenging and remains a key issue to push forward their commercial progress as Pt alternatives in fuel cells and metal‐air batteries. Herein, a facile and economic strategy was proposed to maximize the active sites exposed in porous carbon catalysts by growing dense N‐doped carbon nanonodules firmly located within carbon fiber networks (NCN@CF) via the in situ polymerization of dopamine on bacterial cellulose fibers and a subsequent carbonization process. This metal‐free hybrid catalyst exhibits enhanced ORR activity and better stabilities against long duration and the methanol crossover effect than the commercial Pt/C catalyst in 0.1 M KOH. Notably, when the NCN@CF hybrid was used as an air electrode catalyst in a Zn‐air battery, the as‐fabricated battery presented a larger peak power density of 168 mW cm −2 , higher specific capacity of 720.5 mA h g −1 and energy density of 900.0 Wh kg −1 compared to those based on commercial Pt/C and most N‐doped carbon catalysts ever reported, evidencing its highly promising use as a Pt‐alternative catalyst for the ORR.