DFT study: Cr functionalized porous SnC monolayer for capture of greenhouse gases

Abstract

The tin carbide monolayer (2D-SnC) is an attractive system owing to its structural stability and modifiable electronic response. The introduction of porosity into the lattice not only favors the diffusion of molecules such as CO2, CH4, SO2, and SF6, but also enhances gas–surface interactions by reducing steric barriers. However, in its pristine state, 2D-SnC exhibits relatively weak interactions with unreactive gases, limiting its performance as a sensor. To overcome this limitation, functionalization with transition atoms, particularly Cr, has proven to be an effective method for activating surfaces. In Cr-functionalized porous 2D-SnC (p2DSnC) systems, a significant increase in the adsorption energy and modifications in the density of states were observed, resulting in a more pronounced electronic response after gas interaction. This effect is particularly relevant for relatively unreactive species, such as CO2, CH4, and SF6, whereas for SO2, the interaction is further enhanced, potentially reaching regimes close to chemisorption. Overall, the combination of structural porosity and Cr functionalization in SnC monolayers offers a promising platform for the selective and sensitive detection of greenhouse gases by simultaneously optimizing the adsorption, charge transfer, and electronic response of the system. The Cr -p2DSnC was the most stable when the Cr atom was located above a carbon atom. The binding and formation energies of 2 and -1.2 eV, respectively, indicate that the adsorption of Cr atoms on p2DSnC is energetically favorable. The adsorption energy analysis supports the fact that the average adsorption energies are within the expected range, with SO2 exhibiting the strongest adsorption at 1.96 eV and CH4 exhibiting the lowest at approximately 0.39 eV. Taken together, these results demonstrate that Cr-decorated SnC monolayers are potential sensors for greenhouse gases and promising candidates owing to their combination of stable physisorption and favorable operating conditions.

Keywords: Greenhouse gases; 2D-Materials; DFT