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

Abstract

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.