Facile in situ synthesis of nanofluids based on ionic liquids and copper oxide clusters and nanoparticles

Abstract

Two stable nanofluids comprising of mixed valent copper(i,ii) oxide clusters (<1 nm) suspended in 1-butyl-3-methylimidazolium acetate, [C 4 mim][OAc], and copper(ii) oxide nanoparticles (<50 nm) suspended in trioctyl(dodecyl)phosphonium acetate, [P 8 8 8 12 ][OAc], were synthesised in a facile one-pot reaction from solutions of copper(ii) acetate hydrate in the corresponding ionic liquids. Formation of the nanostructures was studied using 13 C NMR spectroscopy and differential scanning calorimetry (DSC). From a solution of Cu(OAc) 2 in 1-ethyl-3-methylimidazolium acetate, [C 2 mim][OAc], crystals were obtained that revealed the structure of [C 2 mim][Cu 3 (OAc) 5 (OH) 2 (H 2 O)]·H 2 O, indicating the formation of copper hydroxo-clusters in the course of the reaction. Synthesised nanostructures were studied using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Physical properties of the prepared IL-nanofluids were examined using IR and UV-VIS spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and densitometry. © The Royal Society of Chemistry.