Enhanced N2 affinity of 1T-MoS2 with a unique pseudo-six-membered ring consisting of N–Li–S–Mo–S–Mo for high ambient ammonia electrosynthesis performance

Abstract

The Haber–Bosch process is widely used to convert atmospheric nitrogen (N₂) into ammonia (NH₃). However, the extreme reaction conditions and abundant carbon released by this process make it important to develop a greener NH₃ production method. The electrochemical nitrogen reduction reaction (NRR) is an attractive alternative to the Haber–Bosch process. Herein, we demonstrated that molybdenum sulfide on nickel foil (1T-MoS₂–Ni) with low crystallinity was an active NRR electrocatalyst. 1T-MoS₂–Ni achieved a high faradaic efficiency of 27.66% for the NRR at −0.3 V (vs. RHE) in a LiClO₄ electrolyte. In situ X-ray diffraction and ex situ X-ray photoemission analyses showed that lithium ions were intercalated into the 1T-MoS₂ layers during the NRR. Moreover, theoretical calculations revealed the differences between six membered rings formed in the 1T-MoS₂ and 2H-MoS₂ systems with Li intercalation. The bond distances of d(Mo–N) and d(N–Li) of in Li–1T-MoS₂ were found to be shorter than those in Li–2H-MoS₂, resulting in a lower energy barrier of N₂ fixation and higher NRR activity. Therefore, 1T-MoS₂–Ni is promising as a scalable and low-cost NRR electrocatalyst with lower power consumption and carbon emission than the Haber–Bosch process.