N-Doped Porous Carbons Derived from Cross-Linked Polybenzoxazine as Efficient Catalysts for ORR in Alkaline Electrolyte

Abstract

As a promising class of metal-free oxygen reduction reaction (ORR) catalysts, N-doped carbon (NDC) catalysts have attracted widespread attention owing to their high stability, high conductivity, good poison tolerance, and environmental friendliness. We herein report the fabrication of NDC catalysts by using triphenylimidazole-containing polybenzoxazine (TPB) as the precursor. The TPB is firstly Friedel–Crafts cross-linked in CCl4 by using anhydrous AlCl3 as the catalyst. The cross-linked TPB is then pyrolyzed at 800 °C–1000 °C, giving O-containing NDC catalysts. The as-fabricated NDC-900 catalyst has a particulate morphology together with a high BET surface area (947 m2 g−1) and a highly ORR active N content (3.39 at%). Compared to the commercial Pt/C catalyst, the NDC-900 catalyst exhibits a higher ORR activity in alkaline media as evidenced by the higher onset potential (E o, 0.986 vs 0.964 V), higher half-wave potential (E 1/2, 0.845 vs 0.815 V), and higher current density at 0.92 V (J @0.92, 0.251 vs 0.141 mA cm−2). Moreover, the NDC-900-based Zn-air battery achieves a maximum power density of 131.4 mW cm−2 at 204.8 mA cm−2 and a high specific capacity of 818.4 mAh g−1 Zn at 5.0 mA cm−2.