Facile synthesis of aqueous silver nanoparticles and silver/molybdenum disulfide nanocomposites and investigation of their nonlinear optical properties

Silver nanoparticle (AgNP) aqueous colloids with different surface plasmon resonance (SPR) frequencies were controllably synthesized by a facile and green chemical synthesis method. The obtained AgNPs with an average diameter of ~ 15 nm show a symmetrical SPR peak at ~ 400 nm. Another longitudinal SPR mode at ~ 520 nm occurs when increasing the amount of ethanol according to the ultraviolet–visible light spectra. The third-order nonlinear optical (NLO) absorption properties of the AgNP colloids were found to switch from two-photon absorption (TPA) to saturable absorption (SA) by tuning the SPR frequency using Z-scan technique with 340 fs pulses at 515 nm. When combined with two-dimensional (2D) MoS₂, an enhanced SA response is observed for Ag/MoS₂ nanocomposites compared with the counterparts. The nonlinear absorption coefficient of Ag/MoS₂ nanocomposites is about − (10.93 ± 0.6) × 10^–2 cm·GW⁻¹, which is almost three times higher than that of MoS₂. Our work has an instructive value in promoting the potential application of AgNPs and its nanocomposites in optoelectronic and photonic devices, such as optical limiting and ultrafast laser pulse generation.