Plasma-driven electrocatalytic ammonia synthesis: a pulsed NOx replenishment strategy

Abstract

Ammonia (NH₃) is emerging as a carbon-free energy carrier and chemical feedstock essential for the clean energy transition. Herein, we present an integrated plasma-electrocatalytic tandem system for sustainable ammonia synthesis directly from air and water. In this process, a rotating gliding arc plasma activates atmospheric nitrogen and oxygen to generate NO_x intermediates, which are subsequently electrochemically reduced to ammonia on a Cu₂O-based catalyst. By dynamically balancing plasma-derived NO_x generation (67 mM within 15 min) and electrocatalytic consumption, a pulsed NO_x replenishment strategy is established to maintain stable NO_x concentrations (65–70 mM) during prolonged operation. This approach achieves a high ammonia yield rate of 0.648 mmol h⁻¹ cm⁻² and a faradaic efficiency of 86.97%, sustaining continuous performance without depletion. The study demonstrates a scalable and energy-efficient route for green ammonia synthesis, offering a promising pathway for decentralized, renewable-powered nitrogen fixation.