Reversible photoluminescence sensing of gaseous alkylamines using CdSe-based quantum dots

We report here a novel, sensitive detection method for gaseous amines (primary, secondary and tertiary) using thin films of CdSe-based core-shell type quantum dots (CdSe/ZnS and CdSeTe/ZnS) deposited on a glass substrate. The photoluminescence intensity of the quantum dot thin films rapidly decreased on exposure to amine gas in air, and it reversibly recovered after the atmosphere was changed back to air without amine gas. On the other hand, oxygen, nitrogen, argon, carbon dioxide, or hydrogen, all components of natural air, did not affect the photoluminescence intensity of the quantum dot thin films. Interestingly, the photoluminescence of quantum dot films showed higher sensitivity to n-alkylamines, such as hexylamine, when compared with bulky or branched molecules, such as diethylamine and triethylamine. Furthermore, thin films of green-emitting quantum dots showed higher sensitivity to amines when compared with red-emitting ones, which was attributed to the large surface-to-volume ratios of smaller quantum dots. The reversible, reproducible, and selective responses of CdSe-based core-shell type quantum dots to gaseous amines in air suggested that quantum dot thin films could be promising photoluminescence-based optical amine gas sensors. (C) 2017 Elsevier B.V. All rights reserved.