Mn₃O₄ nanoparticles@reduced graphene oxide composite: An efficient electrocatalyst for artificial N₂ fixation to NH₃ at ambient conditions

Currently, industrial-scale NH₃ production almost relies on energy-intensive Haber-Bosch process from atmospheric N₂ with large amount of CO₂ emission, while low-cost and high-efficient catalysts are demanded for the N₂ reduction reaction (NRR). In this study, Mn₃O₄ nanoparticles@reduced graphene oxide (Mn₃O₄@rGO) composite is reported as an efficient NRR electrocatalyst with excellent selectivity for NH₃ formation. In 0.1 M Na₂SO₄ solution, such catalyst obtains a NH₃ yield of 17.4 μg·h^-1·mg_cat.^-1 and a Faradaic efficiency of 3.52% at -0.85 V vs. reversible hydrogen electrode. Notably, it also shows high electrochemical stability during electrolysis process. Density functional theory (DFT) calculations also demonstrate that the (112) planes of Mn₃O₄ possess superior NRR activity.