Engineering Reductive Iron on a Layered Double Hydroxide Electrocatalyst for Facilitating Nitrogen Reduction Reaction

Ammonia is an indispensable chemical, of which the industrial production is still dominated by Haber-Bosch process operated at harsh conditions. The ecofriendly electrocatalytic N₂ reduction reaction (NRR) emerges as an alternative, however, such technique currently suffers from tough dynamics on account of difficulties in the adsorption or protonation of N₂ on catalysts. To eliminate the obstacle, a simple and valid strategy of ferrous iron replacing copper is proposed to regulate the electronic structure of layered double hydroxide (LDH) for boosting the NRR activity. Thanks to the ferrous iron, the Fe(II)Cu(II)Fe(III)-LDH catalyst attains a NH₃ yield rate of 33.1 ± 2.5 µg h⁻¹ mg_cat.⁻¹ and a desirable Faradaic efficiency (FE) of 21.7 ± 1.8% in a neutral electrolyte of 0.1 m Na₂SO₄, outclassing the Cu(II)Fe(III)-LDH catalyst without Fe(II). The introduction of ferrous iron can adjust the d-band center position to improve the N₂ adsorption and can reduce the energy barrier of the potential determining step (PDS) to facilitate the NRR process. This work provides a new insight on engineering efficient electrocatalysts for nitrogen fixation under ambient conditions.