Resolving Competitive Adsorption Pathways on Ir-WSe ₂ Nanosheets via DFT Simulations for Ultra-Selective NO Recognition in Harsh Environments

Accurate NO detection in industrial waste gas is often hindered by H2O and CO2. Therefore, highly selective sensing materials are needed. This study uses density functional theory (DFT). It explores the NO-selective performance of Au-, Pt-, and Ir-modified monolayer WSe2 nanosheets with H2O and CO2 present. Computational results show small binding energy changes in doped systems, maintaining structural stability. Ir-WSe2 has the highest binding energy (−5.48 eV). It also has the strongest NO adsorption (−1.77 eV) in a tight configuration. d-band center tuning enhances this adsorption. Crystal Orbital Hamilton Population (COHP) analysis confirms it quantitatively. Density of states (DOS) data show that only NO changes Ir-WSe2 nanosheets’ electronic structure, enabling detectable signals. Molecular dynamics and thermodynamic analysis confirm stable NO adsorption (proceeding spontaneously at 650 K) and fast H2O migration. Thus, Ir-WSe2 nanosheets have great potential for selective NO detection in industrial waste gas.