Highly sensitive CO gas sensor based on ternary metal sulfides PbSbS quantum dots: Experimental and DFT study

Quantum dots (QDs) thin films based on binary metal sulfides (PbS) and ternary metal sulfides (PbSbS) were fabricated utilizing the Successive Ionic Layer Adsorption and Reaction (SILAR) method. Using the Tauc plot, 2.32 eV and 3.22 eV optical bandgaps were calculated for TiO2/Pb5Sb8S17 (TiO2/PbSbS) and TiO2/PbS, respectively. The sensing performance of TiO2/PbSbS and TiO2/PbS QDs has been investigated for the detection of carbon monoxide (CO) gas at room temperature (300 K). At 25 ppm, ∼2.5 times higher CO gas response was measured for TiO2/PbSbS (0.63) than for TiO2/PbS (0.2469) QDs with response/recovery time (tres./ trec) 14.8/10.21 s. Furthermore, TiO2/PbSbS QDs showed a good response of 0.247 with tres./ trec 20 /9 s at 5 ppm. These results provide a simple and highly scalable approach to developing high-performance gas sensors. To understand the gas sensing phenomena of TiO2/PbSbS and TiO2/PbS, a theoretical model has been developed. The simulation results revealed a significant difference in the behavior of TiO2/PbSbS and TiO2/PbS before and after CO interaction. Which have a high level of agreement with experimental results.