Enhanced NH3Synthesis from Air in a Plasma Tandem-Electrocatalysis System Using Plasma-Engraved N-Doped Defective MoS2

Abstract

We have developed a sustainable method to produce NH3directly from air using a plasma tandem-electrocatalysis system that operates via the N2-NOx-NH3pathway. To efficiently reduce NO2-to NH3, we propose a novel electrocatalyst consisting of defective N-doped molybdenum sulfide nanosheets on vertical graphene arrays (N-MoS2/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 NH3production rate of 7.3 mg h-1cm-2at -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 molNH3-1was 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 NO2-to NH3. This study opens up new avenues for efficient NH3production using cascade systems.