Room Temperature and Humidity Resistant NH3 Detection Based on a Composite of Hydrophobic CNTs with Sulfur Nanosheets

A composite of sulfur nanosheets (S-NSs) with hydrophobic carbon nanotubes (H-CNTs) was designed, and a chemiresistive gas sensor based on this composite material was constructed for breath analysis of NH3 detection at room temperature. Taking advantage of the capillary condensation of CNTs, the hydrophobic effect of hexadecyltrimethoxysilane (HDTMS), and the high sensitivity of S-NSs to NH3 detection, the constructed sensor showed an improved humidity-resistant capacity and is capable of detecting breath-relevant NH3 concentrations down to ppb level under high humidity. The fabricated gas sensor exhibited fast response/recovery (18/26 s) and good stability. Online monitoring for exhaled breath analysis shows good recovery with a stable baseline, providing a potential practical application. The research also facilitates the development of commercial low-cost breath analysis sensors.