Triflate-Functionalized MOF Channels Regulate LiF-Rich Solid-Electrolyte Interphase for Efficient Lithium-Mediated Nitrogen Reduction

Lithium-mediated nitrogen reduction (Li-NRR) is regarded as a promising alternative to the conventional Haber–Bosch process for ammonia synthesis. However, in traditional electrochemical environments, the complex and disordered distribution of cations, anions and solvent molecules entails the formation of heterogeneous solid–electrolyte interphase (SEI), which severely impedes reaction kinetics. Inspired by biological ion conduction in cell membranes, we modify the channels of MOF-808 with triflate (–OTf) groups (MOF-OTf) to optimize species distribution within the Li-NRR microenvironment. Comprehensive characterizations reveal that the grafted –OTf groups realize cation recognition via electrostatic interactions, promoting Li + desolvation and providing hopping sites for rapid Li + transport. The locally concentrated Li + ions further react with fluorine species in –OTf to form homogeneous and LiF-rich SEI, which enhances the permeation of Li + , H + and N 2 across the SEI and accelerates the subsequent activation and protonation steps for NH 3 generation. Compared to heterogeneous SEI in pristine MOF-808, the MOF-OTf achieves a Faradaic efficiency of 74.93% and an NH 3 yield rate of 107.98 nmol min −1 cm −2 at −1.0 V vs. Li0/+ app, corresponding to a performance improvement by over 4.5-fold. This bioinspired microenvironment engineering strategy offers a versatile platform for precise interfacial design in electrocatalytic N 2 fixation systems.