4 MNP Catalysis in Ionic Liquids
119
change dramatically depending upon the depth that the sputtered atoms penetrate
into the IL surface. Therefore, a threshold energy must exist for sputtering atoms to
start growing into NPs, as the deposited atoms are not isoenergetic, but their energies follow a Boltzmann distribution [65]. Hence, increasing the discharge current of
the sputtering process will increase the average translational energy of the sputtered
atoms as well the fraction of metal atoms.
The relation between the size of Au NPs with the anion and cation of imidazoliumbased ILs at different temperatures (20–80 °C) was studied by Nishikawa et al. [75].
The 1-n-butyl-3-methylimidazolium cation with different anions (TFSA, FAS, OTf,
PF 6 , BF 4 ) was studied. It was observed that the sizes of Au NPs may be determined
by the competition between the collision frequency of the ejected Au atoms and the
stabilising capability of the anions that form the first coordination shell around the
NPs. The Au NP sizes are closely related to the anion volume. As the anion volume
increased in the order TFSA > FAS > OTf > PF 6 > BF 4 , the diameter of the NPs also
increased. Furthermore, bimetallic alloy NPs have also been prepared by sequential
and simultaneous sputter deposition onto ILs (Table 4.2, entries 14–17) [60, 72–74].
4.5 Metal Nanoparticle Catalysis in ILs
It is believed that the IL creates a layer around the NPs that acts as a catalytic
membrane-like device. Hence, the geometric and electronic properties of metal NPs
supported in ILs can be tuned by the proper choice of the IL cations and anions,
along with NPs that have a strong influence on the residence time/diffusion of the
reactants, intermediates and products in the nano-environment (Scheme 4.1) [20, 21,
57]. In the remainder of this chapter, a short preview of the catalytic application of
the non-supported NPs in ILs in hydrogenation, hydroformylation, Fischer-Tropsch
and carbon–carbon coupling reactions will be given.
Scheme 4.1 Metal-supported NPs in IL membrane-like device [57]. Reproduced by permission of
the American Chemical Society
119
change dramatically depending upon the depth that the sputtered atoms penetrate
into the IL surface. Therefore, a threshold energy must exist for sputtering atoms to
start growing into NPs, as the deposited atoms are not isoenergetic, but their energies follow a Boltzmann distribution [65]. Hence, increasing the discharge current of
the sputtering process will increase the average translational energy of the sputtered
atoms as well the fraction of metal atoms.
The relation between the size of Au NPs with the anion and cation of imidazoliumbased ILs at different temperatures (20–80 °C) was studied by Nishikawa et al. [75].
The 1-n-butyl-3-methylimidazolium cation with different anions (TFSA, FAS, OTf,
PF 6 , BF 4 ) was studied. It was observed that the sizes of Au NPs may be determined
by the competition between the collision frequency of the ejected Au atoms and the
stabilising capability of the anions that form the first coordination shell around the
NPs. The Au NP sizes are closely related to the anion volume. As the anion volume
increased in the order TFSA > FAS > OTf > PF 6 > BF 4 , the diameter of the NPs also
increased. Furthermore, bimetallic alloy NPs have also been prepared by sequential
and simultaneous sputter deposition onto ILs (Table 4.2, entries 14–17) [60, 72–74].
4.5 Metal Nanoparticle Catalysis in ILs
It is believed that the IL creates a layer around the NPs that acts as a catalytic
membrane-like device. Hence, the geometric and electronic properties of metal NPs
supported in ILs can be tuned by the proper choice of the IL cations and anions,
along with NPs that have a strong influence on the residence time/diffusion of the
reactants, intermediates and products in the nano-environment (Scheme 4.1) [20, 21,
57]. In the remainder of this chapter, a short preview of the catalytic application of
the non-supported NPs in ILs in hydrogenation, hydroformylation, Fischer-Tropsch
and carbon–carbon coupling reactions will be given.
Scheme 4.1 Metal-supported NPs in IL membrane-like device [57]. Reproduced by permission of
the American Chemical Society