Highly selective NH synthesis from N on electron-rich Bi in a pressurized electrolyzer.

Electrochemical conversion of N into ammonia presents a sustainable pathway to produce hydrogen storage carrier but yet requires further advancement in electrocatalyst design and electrolyzer integration. This technology suffers from low selectivity and yield owing to the extremely strong N≡N bond and the exceptionally low solubility of N in aqueous systems. A high NH synthesis performance is restricted by the high activation energy of N≡N bond and the supply insufficiency of N to active sites. This paper describes the introduction of electron-rich Bi sites into Ag catalysts with a high-pressure electrolyzer that enables a dramatically enhanced Faradaic efficiency of 44.0% and yield of 28.43 μg cm h at 4.0 MPa. Combined with density functional theory results, in situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy demonstrates that N reduction reaction follows an associative mechanism, in which a high coverage of N-N bond and -NH intermediates suggest electron-rich Bi boosts sound activation of N molecules and low hydrogenation barrier. The proposed strategy of engineering electrochemical catalysts and devices provides powerful guidelines for achieving industrial-level green ammonia production.