Real-Time Monitoring and 3D Mapping of Trace Vapors of Explosive Nitroaromatic Compounds at Room Temperature by Gas-Phase Scanning Electrochemical Microscopy

Abstract

Development of sensing technologies for trace vapors of nitroaromatic compounds (NACs) is highly desired due to the toxic and explosive nature of the target molecules. Here, a NAC sensor based on a membraneless ionic liquid electrochemical cell was developed and applied for room-temperature trace vapor detection. Submicrometer working electrode dimensions yielded maximized portability and cost efficiency and extremely short time scales for molecular identification. The nanoprobe exhibited detection limitscomparable to those of state-of-the-art NAC sensors. The most noteworthy feature was the fast response to trace vapors, allowing for real-time detection of NACs without sample pretreatment. The pulled capillary form factor of the developed sensor enabled its application as tip electrodes in gas-phase scanning electrochemical microscopy (SECM). With the degree of freedom in three dimensions, mapping of the differential vapor pressure of NACs was possible, leading to potential application of the probe in sniffing out the source of explosive gas dissemination.

Fluorescent Probes for Detection of Environmental Contaminants (NACs & VOCs): Probe Design from a Supramolecular Perspective

“…[51,52] We have mostly focused on the recognition of explosives or their simulants NACs in water, where the electrondeficient nature of these NACs enables them to interact with electron-rich fluorophores. [53][54][55] Furthermore, most of the aromatic VOCs, i. e., benzene, toluene, and xylene derivatives, are electron-rich systems and can interact effectively with the electron-deficient fluorescent chemosensors through intermolecular π-π stacking and hydrophobic interactions. [56][57][58] The nature of the electron transfer process predominantly depends upon the band energies of both the fluorophore and sensing analytes which has been discussed in detail afterward.…”

“…Subsequently, a drastic change in the microenvironment around the probe molecules is observed which leads to distinct changes in optical responses [51,52] . We have mostly focused on the recognition of explosives or their simulants NACs in water, where the electron‐deficient nature of these NACs enables them to interact with electron‐rich fluorophores [53–55] . Furthermore, most of the aromatic VOCs, i. e., benzene, toluene, and xylene derivatives, are electron‐rich systems and can interact effectively with the electron‐deficient fluorescent chemosensors through intermolecular π‐π stacking and hydrophobic interactions [56–58] .…”