Nitroaromatic explosives detection using electrochemically exfoliated graphene

Abstract

Detection of nitroaromatic explosives is of paramount importance from security point of view. Graphene sheets obtained from the electrochemical anodic exfoliation of graphite foil in different electrolytes (LiClO4 and Na2SO4) were compared and tested as electrode material for the electrochemical detection of 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT) in seawater. Voltammetry analysis demonstrated the superior electrochemical performance of graphene produced in LiClO4, resulting in higher sensitivity and linearity for the explosives detection and lower limit of detection (LOD) compared to the graphene obtained in Na2SO4. We attribute this to the presence of oxygen functionalities onto the graphene material obtained in LiClO4 which enable charge electrostatic interactions with the –NO2 groups of the analyte, in addition to π-π stacking interactions with the aromatic moiety. Research findings obtained from this study would assist in the development of portable devices for the on-site detection of nitroaromatic explosives.

Synthesis of Organophilic Carbon Dots, Selective Screening of Trinitrophenol and a Comprehensive Understanding of Luminescence Quenching Mechanism

“…O1s high resolution spectrum supports the existence of C-O-C, C-OH, C=O and C-O linkages in OCDs (Figure 1D). Further, 13 C NMR spectrum confirmed the presence of carbonyl carbon of ester (d 171 and 178 ppm), aromatic nucleus (d 157, 142, 127 and 114 ppm), sp 3 hybridized C that are directly bonded to O atoms (d 57 to 73 ppm) and that are away from O atoms (d 23 to 32 ppm) ( Figure S2). All these observations confirm the formation of CDs with sp 2 hybridized aromatic nucleus feathered with an ample number of ester, ether, alkyl and hydroxyl functional groups.…”

“…to this solution unable to phase separate CDs, indicating the high non-polar nature of OCDs. Chemical nature of OCDs were understood by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron (XPS) spectroscopy and 13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 spectroscopy. Vibrational signatures (see Figure 1B) observed at 2962 and 1412 cm À1 corresponds to = C-H stretching and bending mode of OCDs, respectively.…”

“…Supporting Information contains detailed synthesis of OCDs, sample preparation for screening of NAs and quenching mechanism, materials and methods, survey scan XPS spectrum and SAED pattern of OCDs, 13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57…”

“…Nitroaromatics (NAs) are a class of organic compounds, which are extensively exploited in explosive devices and as precursors for many industrial products. On account of homeland security, environmental screening and militancy, a number of detection strategies based on electrochemical, optical or mass spectrometry were employed to identify the NAs in the past . Among these tools, optical sensors, in particular, fluorescence based sensors are highly advantageous due to its high signal throughput, robustness and specificity.…”

“…On account of homeland security, environmental screening and militancy, a number of detection strategies based on electrochemical, optical or mass spectrometry were employed to identify the NAs in the past. [10][11][12][13][14] Among these tools, optical sensors, in particular, fluorescence based sensors are highly advantageous due to its high signal throughput, robustness and specificity. A wide range of fluorophores, particularly, fluorescent polymers, [15] metal organic frameworks, [16] fluorescent semiconductor QDs [17] and organic small molecule fluorophores [18,19] have been scrutinized as fluorescence signaling agents for NAs.…”