Selective Detection of H2S Gas Using a Tin (II) Sulfide Based Chemiresistive Sensor with Schottky Contact

Selective detection of hydrogen sulfide
$(\mathrm{H}_{2}\mathrm{S})$
gas is of great interest because of its direct impact on human health, the environment, and various industries including food, oil, construction, and medicine, which can also aid in early halitosis diagnosis. Therefore, this study presents a tin (II) sulfide (Sn
$S$
) based chemiresistive sensor for
$\mathrm{H}_{2}\mathrm{S}$
gas detection, where Sn
$S$
is synthesized using a straightforward solvothermal technique, then verified using XRD and TEM analyses. The sensor is then fabricated with drop-coat technique and optimized to achieve maximum sensing performance by fine-tuning the operating temperature. The gas-sensing characteristics are then thoroughly measured at the optimized temperature of
$100\ ^\circ \mathrm{C}$
. Gas-sensing characteristics revealed that the sensor exhibits a wide dynamic range, an experimental detection limit of 0.875 ppm, good repeatability at 100 ppm and 50 ppm, and excellent selectivity to
$\mathrm{H}_{2}\mathrm{S}$
gas over other gases. This performance can be attributed to higher surface-to-volume ratio of Sn
$S$
NPs, and Schottky contact at the interface between the gold electrode and Sn
$S$
NPs. Interestingly, while Sn
$S$
is known to be a p-type semiconductor, the gas-sensing results indicate an n-type semiconductor behavior, which can be explained by the Schottky contact at the interface between Au and Sn
$S$
. With its promising gas-sensing properties, the results of this study indicate that Sn
$S$
has the potential to detect various gases with high sensitivity and selectivity by exploring different nanostructures.