Nano-Ferric Oxide Embedded in Graphene Oxide: High-performance Electrocatalyst for Nitrogen Reduction at Ambient Condition

Nitrogen (N-2) fixation at ambient condition by electrochemical N-2 reduction reaction (NRR) is energy-efficient and eco-friendly as compared to the traditional Harber-Bosch process, but it is extremely challenging. Development and design of high-performance NRR electrocatalysts are indispensable to achieve the goal. In this work, a strongly coupled hybrid of nano-Fe3O4 with reduced graphene oxide (rGO) is synthesized via an in situ redox hydrothermal approach, and the synthesized Fe3O4@rGO hybrid has excellent activity, selectivity, and stability as an NRR catalyst. The NH3 yield rate of 28.01 mu g h(-1) mg(-1) at -0.3 V and the Faradaic efficiency (FE) of 19.12% at -0.1 V are obtained in 0.1 M Na2SO4 solutions at ambient conditions. The superior NRR performance is attributed to the chemical coupling effect between rGO and nano-Fe3O4 particles, which leads to the enhancement of the binding affinity to N-2 molecules, improvement of the conductivity, and lowering the free energy of reaction for the limiting reaction step. This work provides a facile route in fabricating hybrid NRR catalysts with superior performance and shed lights on the reaction mechanism with theoretical mechanistic calculations.

Automated summary

This study synthesized a hybrid of nano-Fe3O4 with reduced graphene oxide via an in situ redox hydrothermal approach, which exhibited excellent performance as an NRR catalyst. The superior NRR performance is attributed to the chemical coupling effect between rGO and nano-Fe3O4 particles, which enhances the binding affinity to N-2 molecules and lowers the free energy of the limiting reaction step.