Vacancy-Assisted Selective Detection of Low-ppb Formaldehyde in Two-Dimensional Layered SnS₂

Abstract

A two-dimensional (2D) layered SnS 2 film synthesized by the thermal-chemical vapor deposition method is utilized for detecting formaldehyde (HCHO), which causes a sick building syndrome. A back-gated field-effect transistor (FET)-based SnS 2 sensor successfully detects HCHO with concentrations down to 1 ppb in a nitrogen atmosphere. Sensing measurements performed under dry air conditions also exhibit a clear response to 20 ppb of HCHO, which is more sensitive than the previously reported sensors based on other 2D-layered materials. Moreover, it is found that the sensor possesses a high selectivity for HCHO over other organic species. Theoretical calculations suggest that native sulfur vacancies existing in n-type SnS 2 crystals play an important role in HCHO detection. Actually, oxygen atoms that are unexpectedly detached from HCHO molecules are found to fill the vacancies, giving rise to p-type doping in SnS 2 . As a result, decrease in the drain current of SnS 2 -FET can be found as a signal of HCHO detection. Furthermore, considering the future mass-production of sensors, we demonstrate large-scale growth of the SnS 2 film by means of magnetron-sputtering deposition and subsequent annealing in a diluted hydrogen sulfide atmosphere. The sputtered film is also found to exhibit a good sensing ability to HCHO.

Self-Assembled SnO2/SnSe2 Heterostructures: A Suitable Platform for Ultrasensitive NO2 and H2 Sensing

“…Long-term exposure to air pollutants in urban areas entails adverse health consequences , and considerable environmental impacts. , Chemoresistive sensors allow monitoring of the concentration of noxious gases, , such as NO 2 , CO, SO 2 , H 2 S, and volatile organic compounds, − with detection limits inferior than their corresponding legal threshold concentrations.…”

Recent Progress of Nanostructured Sensing Materials from 0D to 3D: Overview of Structure–Property‐Application Relationship for Gas Sensors

“…Typical TMDs that reported to be applied in gas sensors are WS 2 , MoS 2 , SnS 2 , WSe 2 , MoSe 2 , etc. [ 179–181 ] Most of the research demonstrated that these TMD‐based sensors could respond to NO 2 and NH 3 . However, the gas sensor‐based simple TMDs have the problems of incomplete recovery or very slow response/recovery time due to the strong chemisorption.…”

Inorganic-Diverse Nanostructured Materials for Volatile Organic Compound Sensing

“…PdAu bimetal decorated SnO 2 NShs (synthesized by hydro-solvothermal treatment) were reported for the detection of both acetone and HCHO at 250 • C and 110 • C, respectively, with a LODs down to sub-ppm level [267]. The device also works at high humid condition (94% RH), but interference studies still need more clarification., Hayashi et al proposed the utilization of SnS 2 nanoflake device to detect the HCHO gas [268], which had a LOD down to sub-ppm (0.001/0.02 ppm) and operated at 210 • C. However, details on other sensory properties are currently missing.…”