Al-Decorated CrS ₂ monolayer for gas sensing applications: a first-principles study using DFT and AIMD simulations

Abstract

Abstract In this study, density functional theory (DFT) simulations are employed to investigate the adsorption behavior of CO 2 , NO 2 , CO, and NO molecules on an Al-decorated CrS 2 monolayer. The stability of the decorated system is first assessed through the calculated decoration energy of −2.5531 eV, confirming that the Al atom is strongly anchored on the CrS 2 surface. A systematic analysis of the geometric and electronic properties of the adsorption configurations reveals distinct interaction mechanisms induced by Al decoration. The results indicate significant variations in bond lengths, bond angles, and electronic characteristics following gas adsorption. The calculated adsorption energies are as follows: −0.0647 eV for CO 2 , −0.2458 eV for CO, −0.8228 eV for NO, and −2.2807 eV for NO 2 . These results indicate the following: weak physisorption for CO 2 and CO, moderate interaction for NO, and strong chemisorption for NO 2 . In addition, charge transfer is analyzed between the Al atom and the CrS 2 substrate, as well as between the adsorbed gas molecules and the Al-decorated CrS 2 system. This analysis provides a more comprehensive understanding of the electronic interactions that govern adsorption. Initial molecular dynamics (AIMD) simulations are performed to evaluate the thermal stability of both pristine and Al-decorated CrS 2 at finite temperatures. Overall, this comprehensive theoretical study demonstrates the enhanced sensitivity of Al@CrS 2 toward toxic gas molecules and highlights its potential as an efficient gas-sensing material, offering valuable guidance for the design of advanced CrS 2 -based gas sensors.