Abstract
Charging and aggregation of titania nanosheets (TNS) and spherical titania nanoparticles (TNP) were studied in aqueous solutions of ionic liquids. The pH and the length of the alkyl chain of the IL cations [1-methylimidazolium (MIM+), 1-ethyl-3-methylimidazolium (EMIM+), and 1-butyl-3-methylimidazolium (BMIM+)] were systematically varied in the experiments. No detectable interaction was observed between the IL cations and the positively charged TNS or TNP surfaces at low pH, where the imidazolium derivatives are the co-ions. For the negatively charged titania nano-objects, significant adsorption of MIM+ and EMIM+ took place, leading to charge neutralization and overcharging at appropriate concentrations. The BMIM+ behaved like a simple salt constituent causing charge screening. For both TNS and TNP, the MIM+ < EMIM+ < BMIM+ counterion order was obtained in the critical coagulation concentrations, indicating that MIM+ was the most effective in destabilization of the dispersions. The major interparticle for...
Highlights
Nanomaterials in ionic liquids (ILs) represent novel and versatile systems, which are used in applications ranging from energy storage through biomolecule processing to catalysis.[1−6] ILs are defined as organic salts of low melting point
The colloidal stability of titania nano-objects of sheet-like and spherical morphology was investigated in dispersions containing IL cations differing in their alkyl chain lengths
No significant adsorption of the positively charged IL constituents was observed on the titania nanosheets (TNS) or titania nanoparticles (TNP) surfaces of the same sign of charge
Summary
Nanomaterials in ionic liquids (ILs) represent novel and versatile systems, which are used in applications ranging from energy storage through biomolecule processing to catalysis.[1−6] ILs are defined as organic salts of low melting point They possess several advantageous features including wide electrochemical window, low vapor pressure, and high chemical stability.[7−11] During the development processes of IL materials, nanoparticles are often dispersed in ILs, leading to the formation of colloidal dispersions, glasses, and gels depending on the composition of the samples and on the experimental conditions.[12−16] Apart from ILs, stable colloids were obtained in molten inorganic salts because of the charge density oscillations around the dispersed particles.[17]. The quantitative description of this theory is given in the Received: April 28, 2019 Published: May 2, 2019
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