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 NH 3 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 MoS 2 /C 3 N 4 heterostructure as an active and stable NRR catalyst. MoS 2 /C 3 N 4 exhibited a conspicuously improved NRR performance with an NH 3 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 MoS 2 or C 3 N 4 component. Density functional theory calculations revealed that the interfacial charge transport from C 3 N 4 to MoS 2 could enhance the NRR activity of MoS 2 /C 3 N 4 by promoting the stabilization of the key intermediate *N 2 H on Mo edge sites of MoS 2 and concurrently decreasing the reaction energy barrier. Meanwhile, MoS 2 /C 3 N 4 rendered a more favorable *H adsorption free energy on S edge sites than on Mo edge sites of MoS 2, thereby protecting the NRR-active Mo edge sites from the competing HER and leading to a high FE.