Ascorbic acid-modified dual-metal-organic-framework derived C-Fe/Fe3O4 loaded on a N-doped graphene framework for enhanced electrocatalytic oxygen reduction

The exploration of economical, highly efficient and stable electrocatalysts for the oxygen reduction reaction (ORR) is critical for large-scale industrial applications of clean energy conversion devices. Herein, a facile operation strategy is presented to construct the C-Fe/Fe3O4 nanoparticles embedded in the N-doped graphene framework (denoted as C-Fe/Fe3O4@NGF), which is derived from the introduction of ascorbic acid modified Fe/Zn-MOF guests into the graphene sheet host as a co-precursor and carbonized to obtain a high-performance catalyst. In this configuration, ascorbic acid with moderate acidity can corrode the surface of the MOFs to some extent, thus facilitating the exposure of active sites. As such, the optimized C-Fe/Fe3O4@NGF demonstrates superior ORR performance with a high onset potential (E-onset) of 0.96 V and half-wave potential (E-1/2) of 0.86 V for the ORR. More importantly, the durability and methanol-resistance of C-Fe/Fe3O4@NGF outnumbers those of commercial Pt/C in alkaline media. The presented strategy opens a new avenue for developing highly active MOF-derived electrocatalysts for diverse applications.