Promoting sensitivity and selectivity of NO2 gas sensor based on metal (Pt, Re, Ta)-doped monolayer WSe2: A DFT study

Abstract

In this paper, the interactions of small gas molecules (H2O, CO2, SO2 and NO2) with pure WSe2, Pt-WSe2, Re-WSe2 and Ta-WSe2 monolayer were investigated through using the DFT calculations to explore their potential applications as gas sensing. The adsorption energies, charge transfers and electronic properties of the gas adsorption systems had been calculated to model the gas adsorption behaviors on monolayer WSe2 (pristine and Pt, Re, Ta atom doping), and the band gaps of Pt, Re, Ta doped monolayer WSe2 were all decreased, while monolayer Re-WSe2 was found to be metallic. The results predicted that the adsorption effect of NO2 gas molecule was the best, and the adsorption energy of monolayer Ta-WSe2 was found to be the largest of the molecules studied. Calculations also shown that there were shorter adsorption distance and more charge transfer for Pt-, Re- and Ta-doped systems than that of pure monolayer WSe2. The results confirmed that monolayer Ta-WSe2 could be used as effective and potential adsorbents for toxic NO2 gas molecule.