Computational Investigation of Single-Atom Catalysts Anchored on Nitrogen-Doped Two-Dimensional NbSe₂ for Highly...

The electrochemical CO₂ reduction reaction (CO₂RR) is a promising approach for CO₂ emission reduction, but the development of efficient catalysts remains a major challenge. Here, a series of transition metal/nitrogen-doped NbSe₂ (TM@N₃-NbSe₂) catalysts were selected to systematically investigate the reaction process and catalytic mechanism involved in the conversion of CO₂ to methane (CH₄) through density functional theory (DFT) calculations. The results indicate that CO₂ has two possible adsorption configurations on TM@N₃-NbSe₂ surfaces, namely, physisorption and chemisorption. During the CO₂ chemical adsorption process, a significant amount of charge is transferred from the substrate to CO₂, thereby activating the formation of CO₂ into a bent structure. In contrast, physically adsorbed CO₂ cannot accept electrons from the substrate, resulting in minimal interaction between CO₂ and the TM@N₃-NbSe₂. According to the reaction pathway and limiting potentials, the catalytic activity of TM@N₃-NbSe₂ for CO₂-to-CH₄ conversion can be ranked in the following order: Co > Ir > Pd > Cu > Os > Fe > Rh > Pt > Ag > Ru > Ni > Au. Among them, Co@N₃-NbSe₂ exhibited more prominent catalytic properties, and the free energy change required to be overcome during the conversion of CO₂ to CH₄ is only 0.22 eV. Most TM@N₃-NbSe₂ systems exhibit higher selectivity for the CO₂RR compared to the hydrogen evolution reaction, making them promising candidates as CO₂RR catalysts. This study reveals the mechanism of transition metal and nitrogen codoped two-dimensional materials in CO₂RR, which will help to screen high-efficiency catalysts to improve efficiency and selectivity.