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

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 hiera...