Evaluating the detection and trapping of small gas molecules on hydrogenated siligene

The use of new two-dimensional systems to detect and capture organic molecules remains a vital research area. In this work, we have investigated, by first-principles calculations, the feasibility of using a hydrogenated siligene (HSiGeH) monolayer to detect and capture small gas molecules through a self-propagating reaction mechanism. We have studied the adsorption of formaldehyde (CH2O), acetylene (C2H2), and ethylene (C2H4) on an HSiGeH monolayer with an H-vacancy (including two situations: an H-vacancy on a Si or a Ge atom). In each case, the molecule chemisorbs at the H-vacancy, increasing the C-O or C-C bond lengths, indicating that double and triple bonds of the molecule are partially broken, resulting in unpaired electrons in one C atom of each molecule. We have found that the hydrogenated chemisorbed molecule -with a new H-vacancy formed on the surface- is the most energetically favorable configuration for each reaction. The viability of the reactions was analyzed by describing the minimum energy path (MEP) computed by the climbing image nudged elastic band method (CI-NEB). Our results show that the self-propagating reaction is viable except for one case, where the C2H4 chemisorbs on the monolayer with the H-vacancy on Ge. These results point toward the application of the HSiGeH monolayer as a possible system for novel gas-removal systems.