Direct ammonia synthesis from the air via gliding arc plasma integrated with single atom electrocatalysis

Abstract

Industrial ammonia synthesis revolutionized global agriculture and industry, but it consumes significant amounts of energy and releases vast quantities of CO2. One alternative, electrocatalytic nitrogen reduction generally suffers from a low ammonia yield rate and poor selectivity. Here, a tandem "plasma-electrocatalysis" strategy was proposed to harvest ammonia from the air. An ammonia yield rate (~1.43 mgNH3 cm-2 h-1) with almost 100% faradaic efficiency was achieved during over 50 hours of stable operation at -0.33 V vs. RHE. The ammonia yield rate reached up to ~3.0 mgNH3 cm-2 h-1 with a faradaic efficiency of ~62% at -0.63 V vs. RHE. This marked performance is achieved by separating activation of stable nitrogen molecules via non-thermal plasma, followed by selective ammonia synthesis via a cobalt single-atom electrocatalyst. This strategy may rival the Haber-Bosch process and the aspirational electrochemical nitrogen reduction at a distributed small-size ammonia production based on a techno-economic analysis.