Porous lead sulphide nanowalls structured film for ethanol detection in the short infrared regime

Porosity of semiconductor material has been used for various applications including gas sensing. However, the utilization of such materials for liquid sensing is still unexplored. Keeping this in mind, a highly porous structured film of lead sulphide (PbS) was engineered using a physical vapor deposition process. The fabricated PbS film was characterized for its shape and porosity using SEM, AFM, and Raman spectroscopy. Thus, the prepared PbS film was tested for various analytic aqueous media, such as ethanol, methanol, isopropanol, butanol, acetone, formaldehyde, and water for sensing. It was perceived that the prepared film was selectively responding to ethanol, while no such response was seen for the other analytic aqueous media and water. The prepared film showed a linear response for the detection of ethanol with the sensitivity of ∼0.002 transmission intensity (a.u.) per concentration of water (v/v%) at 1450 nm with a detection limit of 1.1%. Being operated in the short wavelength infrared range, this sensor can find applications in various fields, such as biofuel, medical, and organic chemistry. As compared to refractive index-based sensors which show nonmonotonic behavior with the concentration of water in ethanol, our sensor exhibits monotonic behavior over the whole range.