Enhanced response characteristics of NO 2 gas sensor based on ultrathin SnS 2 nanoplates: Experimental and DFT study

Layered-metal dichalcogenides with extraordinary characteristics of vast surface area, tunable bandgap and superior adsorption capability enable the potential for application in gas sensors. However, the synthesis of effective material for enhanced response performance remains a challenge. Herein, we exploited a fascinating sensitivity and selectivity towards NO 2 gas detection using SnS 2 nanoflakes prepared via the hydrothermal method. SnS 2 nanoflakes with a thickness of 25 nm and an average diameter of approximately 500 nm show the potential for the detection of NO 2 gas at low concentrations of ppb levels. The sensing properties of the SnS 2 sensors were investigated for different concentrations of NO 2 at various operating temperatures. The sensor exhibits the highest gas-sensing response of 161 at 250 ο C upon exposure to 5 ppm of NO 2 gas with fast response and recovery times. In addition, the sensor shows excellent selectivity with a low detection limit of ppb level. The electronic structure and gas-sensing mechanism are elucidated via finding density of states, charge density, and band structure based on DFT study which is calculated by the Vienna ab-initio simulation package (VASP). The considerable small adsorption energy reveals a physisorption of the NO 2 molecules on the SnS 2 surface (-0.174 eV), indicating the SnS 2 nanoflakes are intriguing candidates for the speedy detection of NO 2 gas.