First-principles calculations combined with experiments to study the gas-sensing performance of Zn-substituted SnS.

Abstract

Two-dimensional group-IV monochalcogenides MX (M = Ge, and Sn; X = S, and Se) are explored for their potential in gas-sensing applications. In this work, a combined theoretical and experimental study on pure SnS and Zn-substituted SnS for promising methanol sensors is performed. The adsorption characteristics of methanol on pure and Zn-substituted SnS were first calculated using first-principles based on density functional theory (DFT). It is clarified theoretically that the incorporation of Zn dopant could enhance the adsorption capability of the SnS surface to methanol molecules, thus achieving obvious response enhancement and selectivity improvement. Further experimental investigation is carried out based on the successful synthesis of pure and Zn-substituted SnS with hierarchical architecture via a one-step solvothermal process. Gas-sensing measurement indicates that the Zn-substituted SnS sensor is promising for selective detection of rarefied methanol. At room temperature, the as-synthesized hierarchical SnS with an appropriate amount of Zn-doping can sense methanol vapor of as low as 100 ppb. In particular, Zn-doping can enhance the sensing response of methanol significantly, with a 32.8-fold increase in response value achieved in comparison to that of the pure SnS. The underlying mechanism for the response enhancement of Zn-substituted SnS is also analyzed and demonstrated in detail. The present work demonstrates that Zn-doping is highly effective for improving the response and selectivity of SnS towards methanol vapor, and the Zn-substituted SnS is promising for highly sensitive methanol sensors with low consumption.