Detection of taggants in explosives on nanostructured metal/silver phthalocyanine chemiresistors: Influence of analyte photoactivation

Finally, the taggants were detected on Pd (1 nm)/AgPc chemiresistor in two modes: without- or with- photoactivation. While the dc-response (Sdc) to 190 ppm of non-activated 2-nitrotoluene vapors was negligible, on photoactivation we reached the value of Sdc = 5.8. This significant improvement, which is attributed to the formation of nitrogen dioxide during photoactivation of 2-nitrotoluene, and also negligible interaction of sensor with water vapor as the most common interferent make our method applicable for early detection of tagged explosives in real “field” conditions. The Pd(1 nm)/AgPc sensors exhibited excellent recovery after detection of photoactivated 2-NT. The recovery was achieved by thermal regeneration steps (sensor temperature switches from 40 °C to 120 °C and vice-versa)