Abstract
Developing sensing materials for military explosives and improvised explosive precursors is of great significance to maintaining homeland security. 5-Nitro-1,10-phenanthroline (Aphen)-modified TiO2 nanospheres are prepared though coordination interactions, which broaden the absorption band edge of TiO2 and shift it to the visible region. A sensor array based on an individual TiO2/Aphen sensor is constructed by regulating the excitation wavelength (365 nm, 450 nm, 550 nm). TiO2/Aphen shows significant response to nitroaromatic explosives since the Aphen capped on the surface of TiO2 can chemically recognize and absorb nitroaromatic explosives by the formation of the corresponding Meisenheimer complex. The photocatalytic mechanism is proved to be the primary sensing mechanism after anchoring nitroaromatic explosives to TiO2. The fingerprint patterns obtained by combining kinetics and thermodynamics validated that the single TiO2/Aphen sensor can identify at least six nitroaromatic explosives and improvised explosives within 8 s and the biggest response reaches 80%. Furthermore, the TiO2/Aphen may allow the contactless detection of various explosives, which is of great significance to maintaining homeland security.
Highlights
Common explosives could be classified into military explosives (e.g., nitroaromatic explosives like2,4,6-trinitrotoleune (TNT), 2,4-dinitrotoleune (DNT), 2,4,6-trinitrophenol (PA), etc.), and improvised explosives such as ammonium nitrate (NH4 NO3 ), sulfur (S) and triacetone peroxide (TATP), etc.Developing sensors against military explosives or improvised explosive precursors has important significance for maintaining global security
The TiO2 /Aphen may allow the contactless detection of various explosives, which is of great significance to maintaining homeland security
The peak of 3192 cm−1 is caused by the overlapping of the -OH vibration peak in TiO2 and the C=C vibration peak of the benzene ring in Aphen. These results indicate that the surface of TiO2 is is successfully modified with Aphen
Summary
Developing sensors against military explosives or improvised explosive precursors has important significance for maintaining global security. There are many methods for detecting these explosives, of which, the most traditional method is the use of sniffer dogs. Sniffer dogs have lower working efficiency than sensors since they need a rest for half an hour after working for 20 min. Existing explosive detection methods that are more mature include. X-ray inspection technology, neutron analysis [1,2], fluorescence detection [3,4], electrochemical detection [5], mass spectrometry [6], ion migration method [7], and chromatography [8], etc. Neutron analysis and X-ray detection instrument are cumbersome, expensive, and radiation hazard
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