Investigation of Fe2N@carbon encapsulated in N-doped graphene-like carbon as a catalyst in sustainable zinc–air batteries

Abstract

The rational construction of low cost, efficient, and stable oxygen reduction reaction (ORR) electrocatalysts is important for the commercialization of fuel cells and metal–air batteries. In this article, we report an easy and effective soft-template method to in situ assemble Fe₂N nanoparticles on the surface of N-doped graphene-like carbon (NC). The prepared Fe₂N nanoparticles were covered by a few carbon layers, which promoted the connection of Fe–N_X clusters with graphene to facilitate the formation of Fe–N–C active sites. Fe–N_X and NC units were found to respectively fulfill different functionalities, and commonly afford the sample with excellent performance. The electrochemical data show that the Fe₂N@NC composite with high-purity and good crystalline displays a synergistic enhanced catalytic activity for ORR, including a positive onset potential (0.084 V), a half-wave potential (−0.036 V) and a high electron transfer number (∼4e⁻), as compared to 20% Pt/C. Additionally, the existence of carbon shells wrapped around Fe₂N nanoparticles can restrain their expansion and dissolution. In addition, the as-prepared catalyst was implemented as an air catalyst for zinc–air batteries and was found to display a comparable open circuit voltage of ca. 1.48 V and a maximum power density of 82.3 mW cm⁻². These results demonstrate that the Fe₂N@NC catalyst may serve as a good alternative to precious Pt for ORR in practical applications.