A Bioinspired Strategy for Enhancing Nitrogen Fixation Using Hydrophobic Ionic Liquids

Electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions offers a promising alternative to the energy-intensive Haber–Bosch process for ammonia synthesis. However, the low solubility of N2 and high proton activity in aqueous electrolytes lead to limited yield rates and poor selectivity. Inspired by the structure and function of natural nitrogenase, here, we adopt a “Solid Catalysts with Ionic Liquid Layer” (SCILL) strategy to tailor the liquid microenvironment at the catalyst surface via ionic liquid (IL) coating. An IL of [P6,6,6,14][NTf2], with high N2 solubility and strong hydrophobicity, is immobilized onto a porous copper catalyst (Cu MFs). The resulting hydrophobic IL layer effectively reduces the local proton concentration and availability while simultaneously enriching and activating N2 at the catalytic interface. Compared to the pristine Cu MFs, the modified electrode ([P6,6,6,14][NTf2]@Cu MFs) exhibits a substantially improved NRR performance in 0.05 M H2SO4. This enhancement is further systematically corroborated through a combination of in situ characterizations and theoretical investigations.