Regeneration of porous Fe₃O₄ nanosheets from deep eutectic solvent for high-performance electrocatalytic nitrogen...

The production of ammonia through electrocatalytic nitrogen reduction reaction (NRR) is environmentally friendly and energy-saving, but it still suffers from the low NH₃ yield rate and poor selectivity. Herein, enlightened by the unique solubility of Fe₃O₄ in deep eutectic solvent (DES), we, for the first time, reported a DES-based regeneration strategy to fabricate porous Fe₃O₄ nanosheets utilizing commercial Fe₃O₄ powder as raw materials. The as-regenerated porous Fe₃O₄ nanosheets exhibited satisfactory electrocatalytic performance toward NRR, affording a NH₃ yield rate of 12.09 μg h^-1 mg^-1_cat along with an outstanding Faradaic efficiency (FE) of 34.38% at -0.1 V versus reversible hydrogen electrode (RHE), in the 0.1 M Na₂SO₄ electrolyte. The superior electrocatalytic activity of the as-regenerated Fe₃O₄ nanosheets mainly resulted from their unique sheet-like morphology with large active surface area, high porosity, and abundant oxygen vacancies. Our proposed DES-based regeneration strategy opens a new avenue for the construction of high-performance electrocatalyst from commercial raw materials, holding great promise in NRR.