Surfactant effects on the synthesis of oxide nanoparticles using deep eutectic solvents

Abstract

In this work we report the solvothermal synthesis of iron oxide and zinc oxide using a ternary eutectic mixture of choline chloride, urea and glycerol at three molar ratio of the components 1 : 1 : 1, 1 : 1.5 : 0.5 and 1 : 0.5 : 1.5. The synthesised iron oxide is nanocrystalline with a crystallite size of 67.5 ± 8.9 nm, however ZnO formed larger particles. Water and surfactants can be added to these solvents to change the morphology and porosity of the iron oxide nanoparticles. Hexadecyltrimethylammonium (CTAB) surfactant is shown to form micelles in these solvents, and was used to alter the properties of the synthesised iron oxide. Iron oxide formed in the presence of surfactant remains crystalline with a crystallite size of 55.3 ± 13.6 nm, and contains mesopores that are not present in samples synthesised without surfactant. However, addition of surfactant also decreases the nitrogen accessible surface area of the iron oxide nanoparticles. In contrast, addition of water to the DES increases both the crystallite size and the surface area of the nanoparticles.