Solar Ammonia Synthesis: Near-Complete Conversion of Intermediated Nitrogen Energy Carrier via the N2–NO–NH3 Route

Abstract

N₂ fixation into NH₃ under ambient conditions remains greatly challenging, where a relay scheme by plasma-enabled N₂ oxidation (pN₂OR) and the NO reduction reaction (NORR) can be a practical route. However, the efficient conversion of NO, as the intermediate nitrogen energy carrier, has not been accomplished due to the limited mass transfer of NO in the reaction solution. Here, a tandem pN₂OR and photocatalytic NORR route (N₂–NO–NH₃) is developed to achieve sustainable NH₃ synthesis with near-complete NO conversion. The highly concentrated NO (∼1%), produced via pN₂OR, is introduced to an absorption-photocatalysis scheme, where the efficiencies for synchronous NO dissolution and photoreduction are significantly promoted. This system delivers a near 100% NO conversion ratio and superior NH₃ selectivity (98.33% ± 0.75%) and stability (240 h) in a single-pass continuous flow. This research has successfully developed a highly profitable production route, yielding a substantial profit of $3000 per ton for NH₄COOH as the final product.