Surface-enhanced Raman activity of aluminum-doped molybdenum disulfide nano-prisms prepared by laser ablation in liquids

The laser ablation in liquids (LAL) technique was employed to synthesize Aluminum (Al)-doped Molybdenum Disulfide (MoS 2 ) nano-prisms to investigate how the incorporation of Al modifies their structural and optical properties. We first prepared Aluminum nanoparticles (Al NPs) via picosecond (ps) laser ablation and subsequently added a small amount of MoS 2 powder to the Al NP suspensions. We then further processed the resulting mixture using nanosecond (ns) and ps laser irradiation, while retaining one sample unprocessed for comparison. We examined the structural, morphological, and optical characteristics using X-ray diffraction (XRD), Field-Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Ultraviolet-Visible spectroscopy, and Raman spectroscopy. The XRD data confirmed the presence of the hexagonal MoS 2 phase and indicated a reduction in crystallite size after their fragmentation with ∼8 ns and ∼4 ps laser pulses. The UV–visible spectra showed an increase in the bandgap, which may be attributed to particle size reduction and quantum confinement effects. The FESEM and TEM analyses revealed thinner, smaller MoS 2 nanoflakes with uniform distribution of Al throughout colloidal suspensions. The produced Al-MoS 2 nano-prisms demonstrated an enhancement factor of ∼10 3 −10 4 for the analyte methylene blue and crystal violet dye molecules at concentrations ∼100 μM, ∼50 μM, and ∼1 μM with excitation at ∼532 nm.