Tuning Mass Transport through Pressure Modulation for Lithium-Mediated Nitrogen Reduction

Lithium-mediated nitrogen reduction (LiNRR) produces ammonia at ambient pressure and temperature, and gas diffusion electrodes (GDEs) have advanced its production rate by intensifying nitrogen availability. However, the mass transport of lithium, nitrogen, and proton donor within the GDE and how the balance of their fluxes governs LiNRR performance remain underexplored. Here, we spatiotemporally varied the balance of species fluxes in a LiNRR GDE by dynamically modulating the pressure difference across the electrode, which altered the position of the gas/electrolyte interface. We found that decoupling the pressures applied during the plating and resting steps of pulsed electrolysis leads to higher ammonia production rates compared to the corresponding static pressure conditions. Decoupled pressure modulation enables even lithium plating during electrolysis and fast transport of nitrogen and proton donor during subsequent ammonia formation steps. This strategy may unlock a new design space for LiNRR by dynamically optimizing the reaction interface.