Developing low-priced,yet effective and robust catalysts for the nitrogen reduction reaction (NRR) is of vital importance for scalable and renewable electrochemical NH3 synthesis.Herein,we provide the first demonstration of MoS3 as an efficient and durable NRR catalyst in neutral media.The prepared amorphous MoS3 naturally possessed enriched S vacancies and delivered an NH3 yield of 51.7 μg h-1 mg-1 and a Faradaic efficiency of 12.8% at-0.3 V (RHE) in 0.5 M LiClO4,considerably exceeding those of MoS2 and most reported NRR catalysts.Density functional theory calculations unraveled that S vacancies involved in MoSs played a crucial role in activating the NRR via a consecutive mechanism with a low energetics barrier and simultaneously suppressing the hydrogen evolution reaction.