Iron-nitrogen co-doped hollow carbon sphere with mesoporous structure for enhanced oxygen reduction reaction

摘要

An iron-nitrogen co-doped hollow carbon sphere (FeN-HCS) with a mesoporous structure is designed and prepared via simple pyrolysis of melamine on the surface of Fe3O4 nanospheres. In the reaction, Fe3O4 nanospheres are used both as templates for catalyzing the growth of carbon shells and iron sources to form ORR active sites. The FeN-HCS catalyst obtained exhibits extremely high oxygen reduction activity in an alkaline medium with a half-wave potential of 0.834 V (vs. RHE), which is 5 mV more positive than a Pt/ C catalyst, and shifts negatively by only 6 mV after accelerated degradation tests (ADT). Moreover, the FeN-HCS catalyst shows a clear 4-electron reduction pathway and a high methanol tolerance. The outstanding performance of FeN-HCS can be attributed to its unique hierarchical porous hollow shell structure, which maximizes exposure of active sites and enhances mass transfer. Such a synthetic strategy offers a novel route to prepare functional hollow carbon spheres for energy storage and conversion applications.