A hybrid plasma electrocatalytic process for sustainable ammonia production

Abstract

From nurturing living organisms to feeding billions of people, the transformation of atmospheric nitrogen to ammonia (NH₃) is essential to sustain life on earth. In nature, bacteria and plants can produce ammonia from air and water at ambient conditions via nitrogen fixation processes. To follow this feat, we couple plasma-driven nitrogen oxides intermediary (NO_x) generation and their electrocatalytic reduction to pave the way for scalable green ammonia at ambient conditions. We developed a non-thermal plasma bubble column reactor that brings together dual reactor configuration with multiple discharge schemes and bubble dynamic control to generate NO_x intermediaries at low specific energy consumption of 3.8 kW h mol⁻¹. The NO_x intermediaries were converted to ammonia at a rate of 23.2 mg h⁻¹ (42.1 nmol cm⁻² s⁻¹), using a scalable electrolyzer operating at a low cell voltage of 1.4 V, current densities of over 50 mA cm⁻², and specific energy consumption of 0.51 kW h mol⁻¹ NH₃.