Ionic liquids for the synthesis of metal nanoparticles

Abstract

Ionic liquids (ILs) offer outstanding possibilities as media for manufacturing nanoparticles. Synthesis conditions with high reaction and nucleation rates are achievable leading to the formation of extremely small particles. The IL itself can act as an electronic as well as a steric stabiliser preventing particle growth and particle aggregation. In addition, as highly structured liquids, ILs have a strong effect on the morphology of the particles formed. We have developed two synthesis techniques for the generation of metal nanoparticles that take advantage of the unique properties that ILs offer when compared to conventional volatile organic solvents (VOCs): microwave (MW) synthesis and physical vapour deposition (PVD). The ionic character and high polarisability of the IL renders it highly susceptible to energy uptake via MWs and extreme heating and reaction rates can be achieved. To make full use of the possibilities that ILs offer we have designed a set of reducing ILs which can be used as direct reaction partners for the generation of metal nanoparticles. The negligible vapour pressure of many ILs makes experiments under high vacuum possible and allows for the PVD of metals into ILs. magnified imagePhysical vapour deposition (left) and microwave synthesis of metal nanoparticles in ILs.

Metal oxide and bimetallic nanoparticles in ionic liquids: synthesis and application in multiphase catalysis

“…After evaporation, application of microwave irradiation was seen to fuse the two materials together. Indeed, the PVD method has high potential for the synthesis of a range of novel nanomaterials, as a range of materials may be directly evaporated into the ILs [95] . Binary materials may be achieved via simultaneous or consecutive evaporation of different materials and this presents a " clean " method as only substrate and IL are present, with no other regents needed nor by-products generated.…”

Ionic liquid assisted microwave synthesis route towards color-tunable luminescence of lanthanide- doped BiPO4

“…The ionic liquid namely also serves as the stabilizing agent of the formed nanoparticles and omit the use of additional capping agents. [16] In addition, the cation through its interaction with the generated material may influence the particle size, morphology and even phase. [17] The butylammonium action is a saturated ammonium cation, it possibly can form strong interactions with the particle surface through its ammonium head group.…”

Temperature-independent formation of Au nanoparticles in ionic liquids by arc plasma deposition

“…In parallel, much attention has been devoted to physical processes combined with ILs as capture media [11][12][13]. In physical methods, atoms, clusters and fragments of metals are ejected by sputtering [14][15][16][17], thermal evaporation [18][19][20] or laser ablation [21,22] from the bulk metal and then land on the surface of ILs and diffuse into the ILs to form NPs without any chemical reactions or additional stabilizing agents. Regarding the sputtering deposition technique, it has recently been determined that both the temperature and the stabilizing ability of ILs, especially the type of anion, play key roles as factors that control the size of NPs.…”