1T-MoS2 Nanosheets Coupled with CoS2 Nanoparticles: Electronic Modulation for Efficient Electrochemical Nitrogen Fixation

Electrocatalytic nitrogen reduction reaction (eNRR), a substitute process for the conventional Haber-Bosch for NH3 production, has drawn tremendous attention due to its merits in mild conditions, abundant reactant sources, low energy consumption, and environmental protection. However, electrocatalysts for eNRR are still subjected to low catalytic activity and selectivity. Herein, we constructed a CoS2/1T-MoS2 heterostructure with CoS2 nanoparticles uniformly loaded on 1T-MoS2 nanosheets and applied it as an eNRR electrocatalyst for the first time. Theoretical calculation suggests that electron transfer from CoS2 to 1T-MoS2 across their contact interface optimizes the local electronic structure of 1T-MoS2, where the electron-depletion region near CoS2 is in favor of accepting lone-pair electrons from N2 to enable N2 absorption, and the electron-accumulation region near 1T-MoS2 is conductive to break inert N≡N triple bonds. Unlike pure 1T-MoS2, the potential-determining step (PDS) demonstrates a significantly lower energy barrier. In addition, the weak interaction between CoS2/1T-MoS2 and hydrogen discourages competitive hydrogen evolution reaction. As a result, CoS2/1T-MoS2 exhibited noticeably improved eNRR activity and selectivity, with an NH3 yield of 59.3 μg h-1 mg-1 and a high Faradaic efficiency of 26.6%.