Novel space-confinement synthesis of two-dimensional Fe, N-codoped graphene bifunctional oxygen electrocatalyst for rechargeable air-cathode

Abstract The 2D Fe, N-codoped graphene (2D Fe-NG) with high oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performances for Zn-air batteries (ZABs) is prepared by a facile synthesis method, which used nitrogen-containing polymer (2,5-benzimidazole) (ABPBI), Fe salts and the cationic surface-active agent treated montmorillonite (CMMT) layer template. The vacuum assist and heat treatment of ABPBI/CMMT at 350 °C are the keys of Fe3+ addition. The characterization analysis demonstrates that added Fe3+ exists in the form of Fe-Nx bonds formed by coordination with N species of ABPBI in MMT. Owing to the existed Fe-Nx sites in 2D Fe-NG, it possesses excellent ORR performance better than 2D NG and 20 wt% Pt/C in O2-saturated 0.1 M KOH electrolyte. For OER, the performance of 2D Fe-NG is close to that of RuO2. The self-made ZAB based on 2D Fe-NG exhibits high peak power density, excellent rechargeable performance, and higher D-C cycling stability.