The Electron-Rich Interface Regulated MBene by S-Bridge Guided to Enhance Nitrogen Fixation under Environmental Conditions

Abstract

The underutilization of active sites limits the performance enhancement of 2D transition metal boride (MBene) in electrocatalytic nitrogen reduction reaction (NRR). Herein, a highly efficient NRR electrocatalyst with S atoms bridging Fe and Mo atoms on the surface of MBene is successfully constructed by using an active site electron optimization strategy, which increases the charge density around the Mo active site and enhances the activation ability of the catalyst to N₂ molecules. It is noteworthy that FeS₂-MBene demonstrates a low intrinsic potential for NRR (−0.2 V vs RHE). It is more favorable for the adsorption of nitrogen atoms in comparison to hydrogen atoms, thereby it can effectively inhibit the hydrogen evolution reaction (HER). Under a potential of −0.2 V versus RHE, the ammonia yield rate is 37.13 ± 1.31 µg h⁻¹ mg⁻¹, and the FE is 55.97 ± 2.63%. Density functional theory (DFT) calculations demonstrate that Mo on the surface of MBene serves as a site for the adsorption of N₂. The formation of the heterostructure enhances electron transfer, resulting in the Mo active site becoming an electron-rich state in favor of subsequent hydrogenation steps. This work offers significant insights into the design and utilization of 2D MBene-based catalysts in NRR.