Oxygen vacancy engineering on LiFe_0.5Mn_1.5O₄ spinel for continuous ammonia electrosynthesis from nitrogen

Electrochemical nitrogen reduction reaction (NRR) powered by green electricity holds sustainable potential for delocalizing ammonia production traditionally implemented by the Haber–Bosch process. Unfortunately, the poor efficiency caused by the inertness of nitrogen–nitrogen triple bond and low aqueous solubility of N₂ gas, as well as the unsatisfactory reproducibility reflected by the frequent false positives, largely impede the development in this field. Herein, we demonstrate that LiFe_0.5Mn_1.5O₄ spinel (LFMO) with rich oxygen vacancies is capable of achieving ambient NRR with a Faradaic efficiency of 21.52% and NH₃ yield rate of 22.45 μg·mg_cat⁻¹·h⁻¹ in a H-type cell. Furthermore, hybridizing LFMO with reduced graphene oxide (rGO) on carbonized melamine sponge (CMS) to fabricate a composite cathode enables a high NH₃ yield of 224 μg·cm⁻²·h⁻¹ in the membrane electrode assembly (MEA) with robust reproducibility.