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

Nitrogen (N₂) fixation at ambient condition by electrochemical N₂ 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 μg 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 N₂ 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.