A DFT study of As doped WSe2: A NO2 sensing material with ultra-high selectivity in the atmospheric environment

In this work, the adsorption of toxic gaseous NO and other gas molecules (NO, CO, CO, N, O, SO) on pristine and X-doped (X = Si, P, S, Te, As) two-dimensional (2D) WSe have been detailed studied by performing density functional theory (DFT) calculations. Calculation results of adsorption energies and adsorption distances demonstrate that As-doped 2D WSe (As-WSe) exhibits high selectivity not only towards NO, but also towards NO and SO. However, the charge transfer between NO and the substrate is too small to detect, and chemical bond forms between SO and the substrate; both phenomena make As-WSe substrate more suitable as a substrate material of the NO sensor. To eliminate the interference of SO on the adsorption of NO, coexistence of NO and SO is simulated. Results reveal that although the interaction between SO and the As-WSe substrate is stronger than that between NO and the substrate, SO molecule hardly interacts with the substrate when co-adsorbed with NO. Besides, calculation results of DOS and PDOS further confirm the sensitivity of As-WSe towards NO; and those of the recovery time also highlight the extremely fast recovery rate of As-WSe after adsorbing NO. The present findings make As-WSe monolayer a potential substrate material of NO gas sensors used in the atmospheric environment.