Abstract
We report the interaction between gas molecules (NO2 and NH3) and the SnSe2 monolayers with vacancy and dopants (O and N) for potential applications as gas sensors. Compared with the gas molecular adsorbed on pristine SnSe2 monolayer, the Se-vacancy SnSe2 monolayer obviously enhances sensitivity to NO2 adsorption. The O-doped SnSe2 monolayer shows similar sensitivity to the pristine SnSe2 monolayer when adsorbing NO2 molecule. However, only the N-doped SnSe2 monolayer represents a visible enhancement for NO2 and NH3 adsorption. This work reveals that the selectivity and sensitivity of SnSe2-based gas sensors could be improved by introducing the vacancy or dopants.
Highlights
Two-dimensional transition metal dichalcogenide (2D-TMD) materials have gained great attention due to their unique structural and electrical properties
Since graphene was introduced into the research, other families of 2D materials with layered structures are fast emerging for some better applications. 2D-TMD materials with a narrow tunable band gap and replaceable cation and anion [1,2,3]
On the basis of density functional theory (DFT), we investigate the gas detection properties for NO2 and NH3 adsorbed on the defective SnSe2 monolayer by substitution of the Se site with a single vacancy, O or N
Summary
Two-dimensional transition metal dichalcogenide (2D-TMD) materials have gained great attention due to their unique structural and electrical properties. Since graphene was introduced into the research, other families of 2D materials with layered structures are fast emerging for some better applications. SnSe2 is used as a high-performance photodetector that shows relatively fast photoresponse at room temperature with a high photo-to-dark ratio [4]. 2D-TMDs materials have been applied as gas sensors due to their large surface-area-to-bulk ratio. The SnX2 (X = S, Se)-based gas sensors show a good response to NO2 at room temperature [6,7,8]. The SnSe2 monolayer shows a higher sensitivity for NO2 molecule adsorption than SnS2 in our related work [7,8]. The charge transfers and the flat band contributed by gas adsorption induces the conductivity difference of the SnSe2 monolayer reported in our previous study [8]
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