The homemade explosive, triacetone triperoxide (TATP), is easy to synthesize, sensitive to detonation but hard to detect directly. Vapor sensor arrays composed of a few sensor materials have the potential to discriminate TATP, but the stability of the sensor array is always a tricky problem since each sensor may encounter a device fault. Thus, a sensor array based on a single optoelectronic TiO₂/PW11 sensor was first constructed by regulating the excitation wavelength to discriminate TATP from other explosives. By in situ doping of Na₃PW12O40, a Keggin structure of PW11 formed on the TiO₂ to promote the photoinduced electron-hole separation, thus obviously improving the detection sensitivity of the sensor film and shortening the response time. The response of the TiO₂/PW11 sensor film to TATP under 365, 450 and 550 nm illumination is 81%, 42%, and 37%, respectively. The TiO₂/PW11 sensor features selectivity to TATP and is able to detect less than 50 ppb. The flexibility and stability of the flexible sensor film is also demonstrated with the extent of bending. Furthermore, the sensing response cannot be affected by ambient air below 60% relative humidity.
Keywords: POMs; TATP; TiO2; gas sensitivity; sensor array.