Highly Selective and Sensitive NO Gas Sensor Based on NbTe₂ Monolayers: Unveiling the Role of Electronic Transport Mechanism

Nitrogen-containing toxic gases, commonly generated in chemical industries and combustion processes, pose severe risks to human health and atmospheric environments. Therefore, it is urgently necessary to develop efficient gas-sensing materials for these pollutants. In this study, a systematic investigation was conducted of gas-sensing capabilities in performance of single-layer NbTe₂ toward nitrogen-containing toxic gases (NO, NO₂, N₂O, and NH₃) using a first-principles method based on density functional theory combined with nonequilibrium Green's function methods. The results demonstrate that monolayer NbTe₂ exhibits excellent kinetic stability and metallic characteristics, as evidenced by its intrinsic band structure and density of states. Notably, NO and NO₂ molecules stably adsorb on Te atoms on the NbTe₂ surface, with adsorption energies and Bader charge transfer analyses revealing superior sensing sensitivity toward NO and NO₂ gases, primarily attributed to chemical adsorption mechanisms. N₂O and NH₃ mainly exhibit weakly interacting physical adsorption. Furthermore, transport characteristics highlight the selectivity of NbTe₂-based sensors for NO, achieving maximum sensitivities of 87.09% and 87.86% along vertical and horizontal directions, respectively, significantly surpassing those for NO₂ (27.45% and 15.42%). Microscopic insights from transport spectra under varying bias voltages and scattering states of adsorbed molecules elucidate the enhanced selectivity and sensitivity of NbTe₂ toward NO. These findings provide a theoretical foundation for the application of monolayer NbTe₂ in high-performance, stable NO gas detection, offering a promising strategy for environmental monitoring and industrial safety.