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 N$_2$ 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 [P$_{6,6,6,14}$][NTf$_2$], with high N$_2$ 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 N$_2$ at the catalytic interface. Compared to the pristine Cu MFs, the modified electrode ([P$_{6,6,6,14}$][NTf$_2$]@Cu MFs) exhibits a substantially improved NRR performance in 0.05 M H$_2$SO$_4$. This enhancement is further systematically corroborated through a combination of in situ characterizations and theoretical investigations.