Two-dimensional (2D)/2D Interface Engineering of a MoS2/C3N4 Heterostructure for Promoted Electrocatalytic Nitrogen Fixation

The electrochemical nitrogen reduction reaction (NRR) is a very efficient method for sustainable NH₃ production, but it requires effective catalysts to expedite the NRR kinetics and inhibit the concomitant hydrogen evolution reaction (HER). Two-dimensional (2D)/2D interface engineering is an effective method to design powerful catalysts due to intimate face-to-face contact of two 2D materials that facilitates the strong interfacial electronic interactions. Herein, we explored a 2D/2D MoS₂/C₃N₄ heterostructure as an active and stable NRR catalyst. MoS₂/C₃N₄ exhibited a conspicuously improved NRR performance with an NH₃ yield of 18.5 μg h^-1 mg^-1 and a high Faradaic efficiency (FE) of 17.8% at -0.3 V, far better than those of the individual MoS₂ or C₃N₄ component. Density functional theory calculations revealed that the interfacial charge transport from C₃N₄ to MoS₂ could enhance the NRR activity of MoS₂/C₃N₄ by promoting the stabilization of the key intermediate *N₂H on Mo edge sites of MoS₂ and concurrently decreasing the reaction energy barrier. Meanwhile, MoS₂/C₃N₄ rendered a more favorable *H adsorption free energy on S edge sites than on Mo edge sites of MoS₂, thereby protecting the NRR-active Mo edge sites from the competing HER and leading to a high FE.