In situ growth of ternary metal sulfide based quantum dots to detect dual gas at extremely low levels with theoretical investigations

Abstract

In this paper, The advantage of ternary metal sulfides for the detection of various gas at extremely low concentrations has been explored. Ultrafine TiO2/PbSnS based thin film has been fabricated by the Successive Ionic Layer Adsorption and Reaction (SILAR) method and employed as an effective CO and NO2 sensor. The advanced material characterization technique such as HRTEM and XRD revealed that high-quality PbSnS nanoparticle with a diameter of 19.7 nm and minimum crystallite size of 19.34 nm were obtained. The bandgap of the synthesizing material was estimated by using data of UV visible spectroscopy and reduces from 3.3 eV to 2.3 eV by adding ternary metal sulfide (PbSnS) in TiO2. The sensor also showed the best sensing performance with sensor response 8.3 at 60 ppm of CO and 0.24 at 100 ppb of NO2 at room temperature. The minimum response and recovery time was calculated at 25 ppm and found to be 198 s and 36 s for CO and 16.03 s and 27 s for NO2 23 ppb respectively and the limit of detection (LOD) is extremely low i. e. 3.89 ppm of carbon monoxide and 3.51 ppb for NO2 at room temperature. Density Function Theory has been used to explain the possible sensing mechanism for the sensing of carbon mono oxide and NO2 using PbSnS nanomaterial. The contributions of Sn in TiO2/PbSnS for the enhancement of selective and sensing capability for CO sensing, as well as the contribution of Pb for NO2 sensing, have also been analyzed experimentally as well as theoretically.