Fingerprinting of Nitroaromatic Explosives Realized by Aphen-functionalized Titanium Dioxide

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.