Synthesis of silver nanoparticles using agar–agar water solution and femtosecond pulse laser irradiation

We report a method to synthetize silver nanoparticles using an agar–agar solution illuminated by light from a xenon lamp, followed by irradiation by ultrashort laser pulses. Spherical nanoparticles of ∽100 nm were created by the xenon lamp illumination, and after the ultrashort pulses irradiation their sizes were reduced to under 10 nm. Bideionized water was used as solvent and surfactants or reducing agents were substituted by agar–agar and light, characterizing the process as a ``green'' synthesis, a completely inoffensive procedure for the environment. The xenon light was used to reduce silver ions (Ag+) into metallic silver (Ag0), and the laser irradiation was important to decrease the nanoparticles diameter. The average particles size, size distribution, morphology, and structure were determined by dynamic light scattering (DLS), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and UV/visible absorption spectrophotometry.

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► Green synthesis of spherical silver nanoparticles using agar–agar.
► Reduction of silver nanoparticles diameter by femtosecond pulse laser irradiation.
► Silver nanoparticles of different sizes.
► No additives, such as solvents, surfactants or reducing agents were used in the procedure.