Abstract
This study systematically investigates the structural stability and surface chemical behavior of selected transition metal dichalcogenides (AX2, where A = V, Mo, Pt; X = S, Se, Te) in both 1T and 2H phases. We evaluate surface chemical stability by computing the energetics of oxygen molecule adsorption and subsequent decomposition, simulating the formation of an AO2 surface dioxide monolayer across all compounds. Additionally, the impact of surface oxidation on NO2 sensing performance under varying temperatures and analyte concentrations is examined. Our findings emphasize the critical role of surface oxidation and oxygen competition in accurately predicting and understanding the chemical properties of these materials.