CNT/organic probe-based chemiresistive sensors suffer from the problem of low sensitivity and poor stability due to the unstable and unfavorable CNT/organic probe interface. A new designing strategy of a one-dimensional van der Waals heterostructure was developed for ultrasensitive vapor sensing. By modifying the perylene diimide molecule at the bay region with phenoxyl and further Boc-NH- phenoxy side chains, a highly stable 1D VDW heterostructure SWCNT-probe molecule system was formed with ultrasensitivity and specificity. Interfacial recognition sites consisting of SWCNT and the probe molecule are responsible for the synergistical and excellent sensing response to MPEA molecules, which was proved by Raman, XPS, and FTIR characterizations together with dynamic simulation. Based on such a sensitive and stable VDW heterostructure system, the measured detection limit reached as low as 3.6 ppt for the synthetic drug analogue N-methylphenethylimine (MPEA) in the vapor phase, and the sensor showed almost no performance degradation even after 10 days. Furthermore, a miniaturized detector was developed for real-time monitoring of drug vapor detection.
Keywords: miniaturized detector; single-walled carbon nanotube composites; supramolecular interfacial recognition; synthetic drug vapor detection; van der Waals heterostructures.