Coembedding Fe Single Atom-Coupled MoC Nanoparticles in N-Doped Hierarchically Porous Carbon Cubes for Oxygen Electroreduction.

Abstract

Promotion of oxygen reduction reaction (ORR) kinetics, to a large extent, depends on the rational modulation of the electronic structure and mass diffusion of electrocatalysts. Herein, a ferrocene (Fc)-assisted strategy is developed to prepare Fc-trapped ZnMo-hybrid zeolitic imidazolate framework (Fc@ZnMo-HZIF-50) and the derived Fe single atom coupling with MoC nanoparticles, coembedded in hierarchically porous N-doped carbon cubes (MoC@FeNC-50). The introduced Fc is utilized not only as an iron source for single atoms but also as a morphology regulator for generating a hierarchically porous structure. The redistribution of electrons between Fe single atoms and MoC nanoparticles effectively promotes the adsorption of O2 and the formation of *OOH intermediates during the ORR process. Along with a 3D hierarchically porous architecture for enhanced mass transport, the as-fabricated MoC@FeNC-50 presents excellent activity (E1/2 = 0.83 V) and durability (only 9.5% decay in current after 40000 s). This work could inspire valuable insights into the construction of efficient electrocatalysts through electron configuration and kinetics engineering.