Catalyst-free efficient stoichiometric synthesis of ammonia and oxygen from nitrogen and water driven by γ-rays

Abstract

Sustainable energy-driven ammonia synthesis from N₂ and H₂O at mild conditions is desirable but challenging. Herein, we report an efficient γ-ray-driven stoichiometric N₂ + H₂O reaction to produce NH₃ and O₂ at room temperature with a high NH₃ formation rate of 70.3 µmol h⁻¹ without the use of catalysts. Tannic acid was added as the ˙OH scavenger to shift the water radiolysis reaction equilibrium to maximize the concentrations of e_aq⁻, H_aq⁺ and ˙H species for N₂ reduction and meanwhile suppress the side ˙OH-mediated NH₃ oxidation reaction. Isotope labelling, radical capture and theoretical modelling demonstrates that NH₃ was formed via ˙N₂H, NHNH, ˙NHNH₂, NH₂NH₂ and ˙NH₂ intermediates, while O₂ was formed via ˙OH, H₂O₂ and ˙OOH intermediates. Our catalyst-free γ-ray-driven N₂ + H₂O reaction provides an alternative convenient and efficient route to synthesize NH₃ and O₂ driven by sustainable nuclear energy.