Fingerprinting of Nitroaromatic Explosives Realized by Aphen-functionalized Titanium Dioxide

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.

Qualitative Detection Toward Military and Improvised Explosive Vapors by a Facile TiO2 Nanosheet-Based Chemiresistive Sensor Array

“…For the detection of the military explosives, such as TNT, DNT, and RDX, several nanostructures have been explored as the sensing components, including TiO 2 (B) nanowires (Wang et al, 2011a), GaN/TiO 2 heterostructure (Aluri et al, 2013), organic nanoribbons (Che et al, 2010), carbon nanotubes and ZnO nanowires . Moreover, nanostructured materials, such as Mn 2+ -doped ZnS nanocrystal, Fe-doped ZnO nanomaterial, and Aphendoped TiO 2 nanocrystal, have also been proved to be efficient for the gas sensing of improvised explosives (Qu et al, 2016;Wu et al, 2016;Xie and Liu, 2019). However, these chemiresistors can only detect a few explosive vapors, and the response values are as low as 5% at room-temperature Aluri et al, 2013), leading to the increased possibility of misinforming.…”

“…Nanostructured TiO 2 is proved to be an efficient sensing material toward nitro-explosives detection (Wang et al, 2011a(Wang et al, ,b, 2013Aluri et al, 2013;Tao et al, 2013;Yang et al, 2015). While doping with Apen, the TiO 2 nanocrystal is applied for the detection of limited number of military and improvised explosives under UV-light illustration, including TNT, DNT, PA, S, AN, and TATP (Xie and Liu, 2019). However, the application of undoped TiO 2 nanomaterials in the detection of improvised explosives remains unexplored.…”