Computational design of Nb-Mo dual sites on MoSe2 edges for synergistic urea electrosynthesis

Abstract

Electrochemical synthesis of urea offers a sustainable alternative to conventional industrial processes as a green synthesis strategy. However, challenges remain in activating inert N₂ molecules and the crucial C-N coupling process. In this work, we doped 3d-5d transition metal atoms at the edge of 2H-MoSe₂ (TM-MoSe₂) to form Mo-TM bimetallic active sites and explored their potential for urea electrosynthesis from N₂ and CO by density-functional theory calculations. Based on catalyst stability, N2 adsorption, C-N coupling, and limiting potentials, Ti-, Zr-, Nb-, and Hf-doped MoSe₂ catalysts are identified as high-potential electrocatalysts for urea synthesis. Notably, Nb-MoSe₂ demonstrates remarkable catalytic performance for urea electrosynthesis, characterized by its exceptional stability, ultralow limiting potential (U_L = −0.35 V), small kinetic barrier (0.64 eV), and significant suppression of side reactions. Mechanism investigations reveal that the catalytic activity (U_L) of TM-MoSe₂ catalysts in urea synthesis exhibits a volcano-shaped relationship with the binding strength of *NCON (ΔG_*NCON). Furthermore, the variation of ΔG_*NCON is linearly correlated with the bond lengths of adsorbed *N₂ molecules. The high activity of Nb-MoSe₂ stems from the effective activation of *N₂ by the synergistic effect of Nb and Mo. This study provides theoretical support for the superior performance of Nb-MoSe₂ catalysts in urea electrosynthesis and opens up new perspectives on the potential of transition metal dichalcogenides in electrocatalysis.