Fe-N-C combined with Fe100-x-y-zPxOyNz porous hollow spheres on a phosphoric acid group-rich N-doped carbon as an electrocatalyst for zinc-air battery

Abstract

Replacing the commercial Pt/C with non-precious metal-based electrocatalysts in the proton exchange membrane fuel cells and metal-air batteries is still challenging. Herein, an electrocatalyst (described as Fe-N-C/Fe100-x-y-zPxOyNz/NPC, NPC is N, P co-doped carbon) composed of multiple active components, such as NPC, iron-based porous hollow spheres and Fe-N-C, is reported, which exhibits an excellent activity that is comparable to state-of-the-art Pt/C for half-cell and full zinc-air battery in alkaline media. This catalyst exhibits an excellent activity with a half-wave potential of 0.86 V for the ORR in alkaline media, which is 10 mV more positive than to that of Pt/C (0.85 V), and a gravimetric energy density for zinc-air battery is up to 675 Wh Kgzn−1. The excellent activity is attributed to the synergetic effect of active NPC, iron-based porous hollow spheres (Fe100-x-y-zPxOyNz) and Fe-N-C in its structure. In addition, phosphoric acid groups are partially remained in the structure for our catalyst that make the catalyst excellent hydrophilicity. This work adds a new member into family of non-precious metal-based ORR electrocatalysts.