Enhanced reduction of CO to C2 products on MoS2 nanoribbons by edge engineering†

Two-dimensional (2D) transition metal dichalcogenides (TMDs) nanomaterials, such as MoS₂ and WSe₂, are promising for CO₂ reduction to CO with high selectivity. However, the further reduction of CO to high-value C₂ products is difficult on these 2D TMDs. To solve the challenging issues, we present an edge-engineering strategy by tuning the edge composition of 2D MoS₂ nanoribbons through incorporation based on density-functional theory (DFT) calculations. A group of elements (Nb, Ta, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Bi, Sn, Sb) are searched to obtain the optimal dopants for high reduction activity. We find that the d-band center and electronegativity of the dopants influence the adsorption strength and configuration of CO, respectively. Compared to Mo ions, dopants with lower d-band centers can reduce the limiting potential and enhance the C–C coupling in CO reduction reaction. The targeted C₂ products can be achieved on Fe, Mn, Ta, and Cu-incorporated MoS₂ zigzag edges. Among these, the Cu-incorporated one exhibits the best selectivity for C₂ products (CH₃CH₂OH) due to the lower d-band center energy of Cu ions relative to the Fermi level, which promotes the CO hydrogenation, the C–C coupling, and the product desorption. Our findings may provide guidance for the design of electrocatalysts for selective C₂ production.