Study of a gelated Deep Eutectic solvent metal salt solution as template for the production of size-controlled small noble metal nanoparticles

Deep eutectic solvents (DESs), especially those made of choline chloride and urea mixtures are a different type of ionic liquids recognized for their ability to solubilize metal chlorides. In this work, a well-known long alkyl aminoamide gelator was added to a metal salt solution in DES to obtain a more viscous solution or a more robust gel when introduced at the higher concentrations. These supramolecular gels could be employed as template for the generation of small noble metal nanoparticles of narrow distribution such as AuNPs or CoNPs without need of seed or reducing agent addition, immobilized in the gel matrix and also homogeneous in shape and size. All gel samples were studied by FE-SEM observation, XRD, FT-IR spectroscopy, rheology measurement and DSC. When formed, the isolated nanoparticles were evaluated by UV-vis spectroscopy and TEM observation. Once formed, their average diameters were 15 nm.