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In recent years, the potential of two-dimensional layered metal dichalcogenides for gas-sensing applications has been explored. Both defect engineering and noble metal modification are powerful strategies to achieve higher gas sensitivity. In this paper, a combined experimental and theoretical study on a SnS2-based sensor is performed to demonstrate the effect of individual or cooperative modulation of S-vacancy (Vs) defect and Ag nanoparticles (nano-Ag) on its gas-sensing performance. Gas-sensing measurements indicate that Ag/Vs-SnS2 shows the strongest response upon exposure to ethanol and a response as high as 94.7% when the ethanol concentration was 15 ppm. Especially, the limit of detection value of Ag/Vs-SnS2 calculated based on the low concentration response data is 2.12 ppb, implying its ultra-sensitive characteristic to ethanol vapor. Meanwhile, the response time and recovery time to 5 ppm ethanol are 7 and 45 s, respectively, and the response error is about 1.8%. It is clarified theoretically that both Vs modulation and Ag modification could enhance the adsorption strength of ethanol molecules on the SnS2 surface, and the SnS2 with co-modification of Vs and nano-Ag (Ag/Vs-SnS2) exhibits the strongest adsorption for the ethanol molecule. The potential mechanism for the enhanced response of nano-Ag/Vs-SnS2 was also further analyzed and demonstrated. This work provides an efficient strategy for developing high-quality gas sensors capable of sensitively detecting ethanol at room temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • A valuable strategy guiding the design of gas sensors based on 2D monochalcogenide. • Combination of first-principles calculations and experiment. • First synthesis of nonmetallic doped-SnS. • Realize the detection of NO 2 , NH 3 and SO 2 gas at room temperature. • Reveal the inner connection between theoretical calculation and experiment. The group-IV monochalcogenide of SnS is explored promising for gas sensor applications due to its unique two-dimensional puckered monolayer and superior oxidation resistance. This work focuses on the gas selectivity regulation of SnS monolayer with adjustable doping. To this end, detailed studies for the effects of nonmetallic dopants (X) of Si, P, or Cl in SnS lattice on the selective adsorption of NO 2 , NH 3 , SO 2 are first performed by first-principles calculations. It reveals that the SnS monolayers with Si and P doping exhibit stronger adsorption capability and rapid recovery characteristic towards NH 3 and SO 2 at room temperature, respectively, while Cl-doped SnS could realize the reversible detection of NO 2 at elevated temperature. These theoretical findings were further verified in experiment. Gas-sensing evaluations show the obvious gas selectivity of SnS with different doping of Si, P and Cl towards NH 3 , SO 2 , and NO 2 , respectively. The response magnitude exhibited by the doped SnS is revealed to be positively correlated with the calculated electron transfer. In terms of recovery performance of the doped SnS, intrinsic recovery characteristic could be predicted by the calculation on recovery time, while the measured recovery time reflects the combined effect of material characteristic and environmental factors. [ABSTRACT FROM AUTHOR]