Insitu growth of ternary metal sulphide based quantum dots to detect dual gas at extremely low levels with theoretical investigations

In this paper, The advantage of ternary metal suphiles 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 sulphide (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 sec and 36 sec for CO and 16.03 sec and 27 sec 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.