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.