Controllable synthesis of nitrogen-doped carbon containing Co and Co3Fe7 nanoparticles as effective catalysts for electrochemical oxygen conversion

Sufficient and well-distributed active sites and highly conductive carbon matrix are two important factors to achieve highly efficient electrocatalysts. In this study, we report an adjusted metal-organic frameworks (MOF)-based route for the preparation of nitrogen-doped Fe/Co bimetallic electrocatalysts. With suitable Fe/Co molar ratio (Fe/Co = 1/4.15), Co nanoparticles (NPs) with mild oxidation state and Co3Fe7 alloys wrapped with thin graphene layers are embedded in an integrated and continuous carbon network. The corresponding FC@NCs-4.15 catalyst exhibits excellent oxygen reduction reaction (ORR) activity (onset potential (E-onset) of 0.94 V and half-wave potential (E-1/2) of 0.84 V vs RHE) in alkaline medium, close to commercial Pt/C and superior to the other two FC@NCs. The desirable ORR performance results from the uniform distribution Co3Fe7 active sites, electron density modification from Co NPs to surrounding carbon layers, hierarchical pore structure with large surface area, low carbon content, high pyridinic and graphitic N components. The FC@NCs-4.15 also displays satisfactory methanol crossover tolerance and durability. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

In this study, nitrogen-doped Fe/Co bimetallic electrocatalysts were prepared using adjusted metal-organic frameworks, showing excellent oxygen reduction reaction (ORR) activity and methanol crossover tolerance. The desirable performance is attributed to the uniform distribution of Co3Fe7 active sites, electron density modification, and hierarchical pore structure with large surface area.