Main content area

Synthesis of gold particles at room temperature ionic liquid–ethylene glycol interfaces: effect of processing time and concentration

Lu, Chunli, Majewski, Peter
Journal of materials science 2019 v.54 no.1 pp. 274-285
X-ray photoelectron spectroscopy, ambient temperature, ethylene glycol, gold, ionic liquids, nanogold, nanoparticles, porosity, quaternary ammonium compounds
Gold particles are produced at the interface between the ionic liquid methyltrioctylammonium bis(trifluoromethylsulfonyl)imide (N₈,₈,₈,₁ NTf₂) and ethylene glycol at temperatures up to 180 °C, reaction times between 10 min and 4 h, and AuCl₄⁻ concentrations in N₈,₈,₈,₁ NTf₂ between 0.5 and 8 mg/mL. When changing the concentration of AuCl₄⁻ in N₈,₈,₈,₁ NTf₂, a sudden change in the shape of the particles can be observed from mainly porous agglomerated of gold nanoparticles to polyhedral particles and hexagonal plates of gold independent of the synthesis temperature. At a AuCl₄⁻ concentration in N₈,₈,₈,₁ NTf₂ of 2 mg/mL, the formation of a porous framework of nanoparticles can be observed during reaction times between 10 min and 4 h. The results indicate that controlling the synthesis temperature, reaction, and AuCl₄⁻ concentrations in N₈,₈,₈,₁ NTf₂ allows the formation of gold particles at the interface between N₈,₈,₈,₁ NTf₂ and ethylene glycol with tailored size, shape, and porosity. XPS studies of the particles indicate the existence of ionic components of the ionic liquid on the particles surface which may be a factor for the formation of particular shapes of the gold particles.