Toxic volatile organic compounds sensing by Al₂C monolayer: A first-principles outlook

Adsorption and detection performance of two-dimensional Al₂C monolayer for four toxic volatile organic compounds (VOCs) viz. acetaldehyde, ethylene oxide, vinyl chloride, and benzene are investigated using first-principles calculations based on the periodic density functional theory. The band gap of Al₂C nanosheet is changed substantially from 0.9 eV to 0.52, 1.41, 1.57, and 0.42 eV upon interaction with acetaldehyde, ethylene oxide, vinyl chloride, and benzene molecules respectively. The Al₂C nanosheet maintains its semiconductor properties even after the adsorption of the four VOCs. The adsorption energy of four typical toxic volatile organic compounds (VOCs) viz. acetaldehyde, ethylene oxide, vinyl chloride, and benzene on the Al₂C monolayer is in a range of -1.972 eV to -2.244 eV, which is higher than the adsorption energies obtained for several other VOCs adsorbed on different materials. Larger VOCs adsorption energies on Al₂C monolayer obtained here may lead to adsorption of more VOC molecules on the material and consequently enhanced sensitivity. The results of ab initio molecular dynamics (AIMD) calculations for the studied complexes confirm their stability under the considered conditions of the simulation. Pristine Al₂C monolayer might be a superior adsorbent and a promising sensing medium for toxic VOCs in real applications.