Plasma-Driven Electrocatalytic Ammonia Synthesis: A Pulsed NOx Replenishment Strategy

Abstract

Ammonia (NH3), with its high hydrogen storage density (17.6 wt%) and safe transport characteristics, stands out as a zero-carbon energy carrier in the hydrogen economy. In the clean energy transition, this study proposes a novel plasma-electrocatalysis coupling strategy for sustainable ammonia synthesis from air and water. By utilizing rotating gliding arc plasma to introduce NOx- intermediates rapidly into the electrolyte (reaching 67 mM within 15 min) and precisely regulating the dynamic equilibrium between plasma supplementation and electrocatalytic consumption, we establish a long-term synthesis mechanism through dual-system collaboration. Systematic investigation reveals the influence of plasma parameters (gas flow rate, input power, treatment duration) on NOx- generation. The study introduces a pulsed NOx replenishment strategy to maintain stable NOx- concentrations (65–70 mM) during extended operations, overcoming the limitations of traditional batch-mode systems. This approach achieves an ammonia production rate of 0.648 mmol·h-1·cm-2 and a Faradaic efficiency (FE) of 86.97%, demonstrating a groundbreaking technological pathway for green ammonia synthesis. This work provides insights into the coupling of plasma-assisted nitrogen fixation with electrocatalysis, enabling a more energy-efficient and scalable ammonia production process, ideal for decentralized, renewable-powered applications.