Enhanced NH 3 Synthesis from Air in a Plasma Tandem-Electrocatalysis System Using Plasma-Engraved N-Doped Defective MoS 2 .

We have developed a sustainable method to produce NH 3 directly from air using a plasma tandem-electrocatalysis system that operates via the N 2 -NO x -NH 3 pathway. To efficiently reduce NO 2 - to NH 3 , we propose a novel electrocatalyst consisting of defective N-doped molybdenum sulfide nanosheets on vertical graphene arrays (N-MoS 2 /VGs). We used a plasma engraving process to form the metallic 1T phase, N doping, and S vacancies in the electrocatalyst simultaneously. Our system exhibited a remarkable NH 3 production rate of 7.3 mg h -1 cm -2 at -0.53 V vs RHE, which is almost 100 times higher than the state-of-the-art electrochemical nitrogen reduction reaction and more than double that of other hybrid systems. Moreover, a low energy consumption of only 2.4 MJ mol NH 3 -1 was achieved in this study. Density functional theory calculations revealed that S vacancies and doped N atoms play a dominant role in the selective reduction of NO 2 - to NH 3 . This study opens up new avenues for efficient NH 3 production using cascade systems.