DFT study of CO and O₂ capture on silicon carbide monolayers decorated with alkali-metal atoms

This study examines the interaction of CO and O2 with a lithium, sodium, and potassium decorated and pristine silicon carbide monolayers (SiCML) using the first principles density functional theory. The pristine SiCML shows the capacity to adsorb both CO and O2, with higher adsorption energies for the O2, which dissociates on the surface of the ML with the two O being adsorbed in two equivalent adjacent bridge sites. The results show that the decoration is stable even at room temperature, with the main adsorption sites for the decoration being on top of Si atoms. The decoration generally improves the adsorption energy of both molecules, with the exception of the K-decorated SiCML with adsorbed O2, which creates potassium superoxide that dissociates from the SiCML. The decoration also alters more significantly the electronic band structures by creating some localized states in the band gap that could be used for detection