First-principles realistic prediction of gas adsorption on two-dimensional Vanadium Carbide (MXene)

Gas adsorption capability of some polar and nonpolar analytes on the surface of the two-dimensional, 2D, V2CTx MXene is investigated using first-principles density functional calculations. Also, the effects of surface functionalization on the electronic properties and gas adsorption of V2C MXene are discussed. Results show that, oxygen and hydroxyl surface groups as the main contributors provide the active sites for gas adsorption. Released adsorption energy suggests that gas sensor capability of the V2CTx MXenes can be enhanced in the presence of water molecule as well as high (low) contents of oxygen and hydroxyl (fluorine) surface functional groups. Among the studied analytes, the V2CTx with all three surface termination contents shows the highest response toward the CH3NH2. Remarkably the V2C(OH)0.33F0.05O0.61 plus H2O molecule, S3, can interact chemically (physically) with the H2 (CH4) gas molecule. Furthermore, C2H5OH, C3H6O and CH3OH analytes are adsorbed physically on the MXene with all three surface contents. Remarkably, the S3 exhibits the lowest and highest work function, when the H2 and H2S molecules are absorbed, respectively. The numerical results may be useful to engineer and design gas sensors and nano-devices based on 2D MXenes.