Oxygen vacancy engineering on LiFe _0.5Mn _1.5O ₄ 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 μgmg_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 μgcm^-2 h^-1 in the membrane electrode assembly (MEA) with robust reproducibility.