MoS ₂ -Modified Electrodes for the Lithium Redox Mediated Nitrogen Reduction at Low Overpotentials

High rates of the lithium redox-mediated nitrogen reduction reaction (Li-NRR) typically require significant overpotentials >0.5 V, limiting energy efficiency of the process. Aiming to accelerate the Li-NRR at low overpotentials, we used nickel cathodes modified with a layer-expanded molybdenum disulfide (MoS 2 LE ). Under 15 bar of N 2 and an apparent Li-NRR overpotential of 0.2 V, the MoS 2 LE /Ni electrodes produce NH 3 at an improved yield rate of 90 ± 20 nmol s –1 cm –2 and faradaic efficiency of 57% ± 2%, as compared to 39 ± 4 nmol s –1 cm –2 and 39 ± 5% for unmodified Ni (in 2 M lithium bis(trifluoromethylsulfonyl)imide + 0.1 M C 2 H 5 OH tetrahydrofuran solutions). Characterization of the electrodes suggests that the improved performance stems from the transformation of MoS 2 LE into (poly)sulfide species within the solid electrolyte interphase (SEI). These results broaden our understanding of the Li-NRR performance-SEI relationships, which support the development of practical ammonia electrosynthesis technologies.