Sustainable Ammonia Synthesis from Nitrogen and Water by One-Step Plasma Catalysis

Abstract

Sustainable ammonia synthesis at ambient conditions that relies on renewable sources of energy and feedstocks is globally sought to replace the Haber–Bosch process. Here, using nitrogen and water as raw materials, a nonthermal plasma catalysis approach is demonstrated as an effective power-to-chemicals conversion strategy for ammonia production. By sustaining a highly reactive environment, successful plasma-catalytic production of NH3 was achieved from the dissociation of N2 and H2O under mild conditions. Plasma-induced vibrational excitation is found to decrease the N2 and H2O dissociation barriers, with the presence of matched catalysts in the nonthermal plasma discharge reactor contributing significantly to molecular dissociation on the catalyst surface. Density functional theory calculations for the activation energy barrier for the dissociation suggest that ruthenium catalysts supported on magnesium oxide exhibit superior performance over other catalysts in NH3 production by lowering the activation energy for the dissociative adsorption of N2 down to 1.07 eV. The highest production rate, 2.67 mmol gcat.−1 h−1, was obtained using ruthenium catalyst supported on magnesium oxide. This work highlights the potential of nonthermal plasma catalysis for the activation of renewable sources to serve as a new platform for sustainable ammonia production.