ZnO–Ag hybrids for ultrasensitive detection of trinitrotoluene by surface-enhanced Raman spectroscopy

Abstract

An efficient and green approach was used to fabricate novel and low-cost surface-enhanced Raman scattering (SERS) spectroscopy sensors based on 4-aminothiophenol (4-ATP) functionalized ZnO-Ag hybrid nanoflowers for the detection of explosives. Such SERS sensors exhibited high sensitivity to rhodamine 6G (R6G) at a low concentration of 10(-12) M and an enhancement factor of over 4.12 × 10(6) was achieved. Moreover, the Raman-inactive trinitrotoluene (TNT) initiated the high Raman scattering of non-resonated 4-ATP through the formation of a π-donor-π-acceptor interaction between the π-acceptor, TNT, and the π-donor, the 4-ATP-Ag-ZnO complex, on the flower-like hybrids. Because this π-donor-π-acceptor interaction could effectively induce the "hot spots" for SERS, TNT concentrations as low as 5 × 10(-9) M could be detected. Furthermore, other derivatives of TNT were also explored, and this sensor exhibited better selectivity for TNT than other similarly structured explosives. The low-cost hybrid SERS substrates presented good sensitivity and reproducibility for the analytes employed, demonstrating promising application in forensic science and homeland security.

Electrochemical detection of trinitrotoluene in water samples based on a natural mineral attapulgite modified electrode

“…For example, the detection limit of our electrode is lower than that of the electrochemical TNT sensor based on VO 2 (1 ppb) [34], IL-graphene (4 ppb) [22], and SiO 2 (1.6 ppb) [33]. It is also lower than that of the SERS sensor based on ZnO-Ag nanohybrids (1.1 ppb) [51] and comparable to that of fluorescent sensor based on silica nanoparticles (0.2 ppb) [52]. These results indicate that our developed attapulgite/GC electrode is competitive among many previously reported sensors for TNT detection.…”

Fabrication of hexagonally patterned flower-like silver particle arrays as surface-enhanced Raman scattering substrates

“…The characteristic peaks of R6G at 612 cm −1 , 775 cm −1 and 1361 cm −1 are assigned to C-C-C ring in-plane bending mode, C-C-C ring out-of-plane bending mode, and aromatic C-C stretching vibration mode, respectively. [35] Based on the average SERS spectrum intensity of peak at 612 cm −1 for R6G with different concentrations (5 µM to 0.1 nM) shown in Figure S9, the calibration curve versus the logarithmic concentration of R6G in the main range of linearity was obtained as shown in Figure 5(c). Based on the definition of the limit of detection (LOD) as the concentration at which the signal-to-noise ratio is equal to 3, the LOD to R6G of the as-prepared flower-like Ag-SMP array was estimated to be 0.54 nM.…”

Molecular recognition of 2,4,6-trinitrotoluene by 6-aminohexanethiol and surface-enhanced Raman scattering sensor

“…In the forthcoming studies, we employed pAu/AuNS surface that is modified with AHT monolayer for the SERS based detection of TNT. [25,[52][53][54]. The spectrum also depicts a sharp and intense band at 1375 cm −1 corresponding to NO 2 group symmetric stretching vibration of TNT [25,[52][53][54].…”

“…The spectrum also depicts a sharp and intense band at 1375 cm −1 corresponding to NO 2 group symmetric stretching vibration of TNT [25,[52][53][54]. The band at 1559 cm −1 corresponds to asymmetric NO 2 stretching of TNT [25,[52][53][54]. A closer examination of the AHT:TNT complex spectrum in the CH 2 region (Fig.…”

“…The reason for this is the lack of nitro group in 2,4-DNT prevents distribution of anionic charge throughout the benzene ring and therefore 2,4-DNT may not form Meisenheimer complex with AHT [25]. Although PA has a similar structure to TNT, the OH group can easily lose a proton which would reduce the charge transfer between AHT and PA and thus less likely to form a complex [52]. In order to further confirm the selectivity of the AHT towards TNT, SERS investigation of DNT and PA was carried out on AHT modified surface.…”