Nitrogen fixation in a non-equilibrium spatially distributed electric field

Nitrogen fixation heavily relies on the energy-intensive Haber-Bosch process, necessitating renewable alternatives. Here, we introduce a non-equilibrium spatially distributed electric field (SD-EF) strategy for nitrogen fixation in ambient air plasma. The optimized SD-EF strategy gives a NOx− yield of 9.8 mmol/h, tripling that of a uniform electric field and the N2 conversion is three times higher than most discharge configurations at similar or lower energy consumptions. This high NOx− yield is achieved through simultaneously activating two beneficial kinetic networks via SD-EF by having both high and low electric fields present: O3 and vibrational excitation of N2 (N2(v)) sub-mechanisms, which are revealed by developing a photonic crystal fiber diagnostic for in-situ quantification of molecules and ions (NO, NO2, N2O, O3, NO3−, and NO2−) in gas-liquid plasma. The establishment of the SD-EF strategy, coupled with in-situ gas-liquid diagnostics, is broadly applicable to plasma-assisted nitrogen fixation and holds promise for other plasma-assisted chemical conversion processes. The authors report a non-equilibrium spatially distributed electric field strategy for 2 nitrogen fixation in ambient air plasma.