Synergistic bimetallic CoFe2O4 clusters supported on graphene for ambient electrocatalytic reduction of nitrogen to ammonia

Abstract

The energy-intensive nature, high level of CO₂ emission and sophisticated infrastructure requirement hampered the utilization of the Haber–Bosch process as a green and decentralized system for NH₃ production. The electrochemical N₂ reduction reaction (NRR) provides a promising alternative to fix N₂ under ambient conditions. Here, we report CoFe₂O₄ nanoclusters anchored on reduced graphene oxide for enhanced nitrogen reduction. In contrast to monometallic counterparts, this composite catalyst achieves a faradaic efficiency of 6.2% with a high rate of NH₃ production of 4.2 × 10⁻¹¹ mol s⁻¹ cm⁻² in 0.1 M Na₂SO₄ aqueous electrolyte. Amelioration of NRR performance could be attributed to the availability of different types of adsorption and active sites for N₂ after the incorporation of Co in the Fe₃O₄ structure. Also, the homogeneous dispersion of nanoclusters on a 2D support can achieve higher active site density. This work provides a new category of binary metal oxides catalysts for NRR under ambient conditions.