Hierarchical Laser-Patterned Silver/Graphene Oxide Hybrid SERS Sensor for Explosive Detection

Abstract

We demonstrate an ultrafast laser-ablated hierarchically patterned silver nanoparticle/graphene oxide (AgNP/GO) hybrid surface-enhanced Raman scattering (SERS) substrate for highly sensitive and reproducible detection of an explosive marker 2,4-dinitrotoluene (2,4-DNT). A hierarchical laser-patterned silver sheet (Ag–S) is achieved by ultrafast laser ablation in air with pulse energies of 25, 50, and 100 μJ. Multiple laser pulses at a wavelength of 800 nm and a pulse repetition rate of 50 fs at 1 kHz are directly focused on Ag–S to produce and deposit AgNPs onto Ag–S. The surface morphology of ablated Ag–S was evaluated using atomic force microscopy, optical profilometry, and field emission scanning electron microscopy (FESEM). A rapid increase in the ablation rate with increasing laser energy was observed. Selected area Raman mapping is performed to understand the intensity and size distribution of AgNPs on Ag–S. Further, GO was spin-coated onto the AgNPs produced by ultrafast ablation on Ag–S. The hierarchical laser-patterned AgNP/GO hybrid structure was characterized using FESEM, high-resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. Further, hierarchical laser-patterned AgNP/GO hybrid structures have been utilized as SERS-active substrates for the selective detection of 2,4-DNT, an explosive marker. The developed SERS-active sensor shows good stability and high sensitivity up to picomolar (pM) concentration range with a Raman intensity enhancement of ∼1010 for 2,4-DNT. The realized enhancement of SERS intensity is due to the cumulative effect of GO coated on Ag–S as a proactive layer and AgNPs produced by ultrafast ablation.

Hybrid Surface-Enhanced Raman Scattering Substrates for the Trace Detection of Ammonium Nitrate, Thiram, and Nile Blue

“… 21 − 26 Since the past 2 decades, substantial improvements have been made in achieving diverse nanostructures (NSs) on a wide range of materials such as metals, semiconductors, insulators, and polymers by varying the short/ultrashort laser ablation parameters (pulse duration, wavelength, fluence, number of pulses, and focusing conditions) and surrounding environments (air, gas, and liquid). 21 , 25 , 27 − 34 The ultrashort laser-induced surface structures have proven to be promising candidates in diverse areas such as sensing, 22 , 35 − 39 surface wetting (hydrophobicity and hydrophilicity), 27 electrochemistry, 40 , 41 and plasmonics. 27 , 41 Moram et al have detected several explosive molecules using silicon (Si) microsquared arrays embedded with Ag/Au NP SERS substrates achieved using femtosecond (fs) laser ablation.…”

Enhanced Electrocatalytic Activity of Cobalt-Doped Ceria Embedded on Nitrogen, Sulfur-Doped Reduced Graphene Oxide as an Electrocatalyst for Oxygen Reduction Reaction

“…Figure 2b shows the Raman spectra of GO, N, S-rGO and the Co-CeO 2 /N, S-rGO composite. All samples exhibit two characteristic peaks of the D band at 1350 cm −1 and the G band at 1579 cm −1 [50,51]. The D band is assigned to the sp 3 structural defect sites, and the G band is associated with the sp 2 -bonded graphitic carbon atom.…”

Facile synthesis of noble metal decorated carbon nanostructure for SERS detection

“…Contributed by the synergetic effect of EM and CM, attractive SERS performance on rGO‐Ag/Au, CNT/Ag, MoO x ‐Ag, and TiO 2 ‐Au has been achieved. [ 27–33 ] Nevertheless, the fabrication of hybrids substrate usually requires multiple steps of chemical synthesis and metal deposition, which complicates the preparation process and also increases the time cost. [ 34 ]…”