Plasma-Driven Nitrogen Fixation on Sodium Hydride

Abstract

The development of alternative approaches to the conventional Haber–Bosch ammonia synthesis process is an imperative but very challenging task. Extrinsic stimuli such as plasma could provide greater flexibility in materials selection and process innovation for nitrogen fixation. Hydride (hydrogen anion, H‾)-containing materials have recently shown promise in thermal ammonia synthesis, whereas the interactions of hydrides and N2 under plasma have rarely been investigated. Herein we explore plasma-driven nitrogen fixation to NH3 mediated by an inexpensive and common reagent sodium hydride, which does not react with N2 under normal thermal conditions. Nitrogen plasma can produce reactive nitrogen species and also induce the dehydriding of NaH, which result in the activation and hydrogenation of N2 to surface NaNH2 species. The subsequent thermal-hydrogenation of NaNH2 produces NH3 facilely. The stepwise chemical loop prevents ammonia from plasma-induced cracking. This NaH-mediated chemistry broadens the scope of hydrides as well as many other materials for N2 fixation, and also has prospect for other chemical transformations.