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

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-1cat 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.