Regulating Multifunctional Oxygen Vacancies for Plasma-Driven Air-to-Ammonia Conversion

Abstract

Current ammonia (NH₃) synthesis is hindered by challenges including N₂ activation, NH₃ separation and process complexity. Here, we report a plasma-electrochemical process for the production of gaseous ammonia from air generated NOx, decoupled from processes employing liquid phase intermediaries such as NO₃⁻ and final product (NH4+). Importantly, this process uses air for scalable ammonia production under ambient conditions and directly produces gaseous NH₃ which facilitates efficient product separation. For NOx reduction to NH₃, we propose a universal strategy combining plasma pretreatment and wet chemical calcination to introduce multifunctional oxygen vacancies. The resulting highly defective Fe₂O₃ nanoparticles on Cu achieves a significant ammonia production rate of 628 nmol·s⁻¹·cm⁻2, along with nearly 100% faradaic efficiency.