Fast track to nanomaterials: microwave assisted synthesis in ionic liquid media

Abstract

Herein we present a general approach to metal and metal oxide nanoparticles using simple metal salts as starting materials. The reducing agent can be delivered in the form of the anion incorporated into the metal precursor respectively ionic liquid. Exemplary we demonstrate the synthesis of Cu and Ag as well as ZnO and NiO nanoparticles generated either from acetate or carbonate salts. All particles are synthesised by microwave heating without the necessity of inert conditions. Two different types of ionic liquids have been used as reaction media -tetra-n-butylphosphonium acetate (n-Bu 4 POAc) and 1-butyl-2,3-dimethylimidazolium N,N-bis(trifluoromethylsulfonyl)imid (bmmim NTf 2 ). In this case, the choice of the ionic liquid seems to have significant influence on the size, shape and dispersity of the synthesised particles. It is clearly shown that the acetate anion present in all reaction mixtures can act as an inexpensive and nontoxic reducing agent. The final products in solid, liquid and gaseous phase have been characterised by XRD, TEM, NMR, FT-IR and online gas-phase MS.

Comparative Synthesis of Cu and Cu2O Nanoparticles from Different Copper Precursors in an Ionic Liquid or Propylene Carbonate

“…Kessler 2 ], apparently without the formation of copper oxide, which illustrates the still not fully understood influence of the IL on the decomposition process, nucleation and growth process, stabilization, and morphology of the NPs. [83] Surprisingly, our cubic structures were obtained when only IL was involved. This is a new method of synthesizing Cu 2 ONCs in the absence of any capping agent by just using the IL [BMIm] [BF 4 ].…”

Nanoparticles in ionic liquids: interactions and organization

“…[63][64][65] In fact, metal nanoparticles synthesized in ionic liquids are reported to be mono-dispersed and non-agglomerated as a result of ionic liquid stabilization. Any factors affecting the stability of nanoparticles in ionic liquids may lead to nanoparticle size [70][71][72][73] and/or morphology [74][75][76][77][78] changes during synthesis. Any factors affecting the stability of nanoparticles in ionic liquids may lead to nanoparticle size [70][71][72][73] and/or morphology [74][75][76][77][78] changes during synthesis.…”

Optimization of transition metal nanoparticle-phosphonium ionic liquid composite catalytic systems for deep hydrogenation and hydrodeoxygenation reactions

“…The Pt NPs grew in size from 4.7 ± 1.2 nm to 12.2 ± 6.1 nm upon heating under hydrogen in P [4,4,4,8]Cl. On the other hand, in P [6,6,6,14]Cl, both the initial size of the Pt NPs and the increase in Pt NP size was much smaller (<2 nm increase).…”

“…[1][2][3][4][5] Imidazolium ILs, in particular, have been studied extensively for their remarkable ability to serve as reaction media and/or stabilizers for such NP-catalysed transformations. [6][7][8][9][10] However, the imidazolium ILs offer challenges such as base-induced deprotonation and consequent carbene formation, 11 hydrolysis of anions such as PF 6 − and BF 4 − to generate corrosive acids, 12 variations in the efficiency of NP stabilization induced by the presence of trace amounts of impurities such as unreacted IL precursors, 7,13 and comparatively higher melting points of imidazolium halides, which are not room-temperature ILs. 14 It is surprising, therefore, that tetraalkylphosphonium ILs, which are stable under highly basic conditions, commercially available at high levels of purity, less sensitive to moisture and oxygen than their imidazolium counterparts, and largely present as liquids at room temperature even when combined with highly coordinating anions such as halides, have not been investigated more extensively as potential replacements for imidazolium ILs in catalytic reactions of industrial and environmental importance.…”