A theoretical study of atmospheric pollutant NO2 on as-doped monolayer WS2 based on DFT method

Abstract

For the relevant properties of pristine and doped (Si, P, Se, Te, As) monolayer WS 2 before and after the adsorption of CO, CO 2 , N 2 , NO, NO 2 and O 2 , density functional theory (DFT) calculations are made. Calculation results reveal that the monolayer WS 2 doped with P and As atoms can be substrate materials for NO and NO 2 gas sensors. However, after the subsequent CDD and ELF calculations, it is found that P-doped monolayer WS 2 adsorbs NO and NO 2 in a chemical way, while As-doped monolayer WS 2 adsorbs NO and NO 2 in a physical way. Also, the charge transfer between As-doped monolayer WS 2 and NO is relatively small and not easily detected. Besides, As-doped monolayer WS 2 system exhibits greater differences in optical properties (the imaginary part of reflectivity and dielectric function) before and after the adsorption of NO 2 gas than before and after adsorption of NO gas. These differences in optical properties assist sensor devices in making gas adsorption-related judgments. Through the analysis of the recovery time, DOS and PDOS, As-doped monolayer WS 2 is also verified to be a promising NO 2 sensing material, whose recovery time is calculated to be as short as 0.169 ms at 300 K. • The interactions between five doped two-dimensional WS 2 substrates and six gases including NO 2 are analyzed and compared in detail. • The multi-angle analysis of various adsorption parameters and optical properties allows us to see that As-doped monolayer WS 2 has sufficiently strong selectivity and sensitivity towards NO 2 gas. • As-doped monolayer WS 2 adsorbs NO 2 in a physical way.