12.3 Deposition at the Liquid–Liquid Interface
447
in the process [71]. It was also shown that by tuning the Galvani potential difference
between the two liquids in a thoughtful manner, the dimerization of the monomer
(resulting in sexithiophene) is the dominant reaction, hence opening a synthesis route
for this compound.
Electropolymerization is a feasible tool to prepare polymer/carbon nanotube
composites at the ITIES. The same way as it was used for metal deposition [89],
the accumulation of the nanotubes at the ITIES can serve as both an electron-transfer
medium for the charge transfer between the phases and for the support of the polymer
being formed. This method was evidenced by using pyrrole as monomer and the
[IrCl 6 ]
2– /[IrCl 6 ]
3– redox pair in the aqueous phase [67]. Spectroscopic evidence was
obtained for that the polymer grew onto the carbon nanotube. As compared to the
free-standing polypyrrole film, the nanotube-supported film was of higher density.
The film obtained was easily transferable from the ITIES to another support.
The number of metal/monomer pairs tested so far for electrochemical composite
film formation at the ITIES is very small. The parallel reaction of the precursor metal
ions and the monomers can lead to a composite along the ITIES, hence resulting in
nanoparticle-decorated polymer networks, which may gain a role in catalysis. A
short series of papers is available in this field [78, 83, 84] for tetraoctylammonium
tetrachloroaurate and tyramine dissolved in organic and aqueous phases, respectively.
The direct observation of the particle size distribution confirmed [84] that the mean
particle size can be easily regulated by the Galvani potential difference between the
two liquid phases.
12.3.4 Electrodeposition Near the Solid–Liquid–Liquid
Three-Phase Boundary
Sections 12.2.3–12.4 discussed the nanostructure preparation methods that used no
electrically conducting material under potential control in the vicinity of the liquid–
liquid interface to obtain a nanostructure. In this chapter, various methods are listed
where an electrically conducting plate crosses the ITIES and it is connected as the
working electrode. The reference and the counter electrodes are immersed into the
aqueous phase, and the cell is regulated electrically as a conventional three-electrode
cell. From this point, we shall see a bifurcation depending on which phase contains
the electroactive material and whether the deposition process is an electrochemical
one or it is only electrochemically assisted. The forthcoming discussion will follow
this logical order.
In the studies where a truly electrochemical deposition process takes place
in the vicinity of the three-phase boundary line, the reactant to be reduced is
initially present in the organic phase. In the concept-proofing work [62], the
authors applied HAuCl 4 dissolved in an ionic liquid, 1-decyl-3-methylimidazolium
bis(trifluoromethylsulfonyl)imide. Later, the same technique was applied for toluene
as non-aqueous phase [98], hence inverting the density ratio of the contributing phases
447
in the process [71]. It was also shown that by tuning the Galvani potential difference
between the two liquids in a thoughtful manner, the dimerization of the monomer
(resulting in sexithiophene) is the dominant reaction, hence opening a synthesis route
for this compound.
Electropolymerization is a feasible tool to prepare polymer/carbon nanotube
composites at the ITIES. The same way as it was used for metal deposition [89],
the accumulation of the nanotubes at the ITIES can serve as both an electron-transfer
medium for the charge transfer between the phases and for the support of the polymer
being formed. This method was evidenced by using pyrrole as monomer and the
[IrCl 6 ]
2– /[IrCl 6 ]
3– redox pair in the aqueous phase [67]. Spectroscopic evidence was
obtained for that the polymer grew onto the carbon nanotube. As compared to the
free-standing polypyrrole film, the nanotube-supported film was of higher density.
The film obtained was easily transferable from the ITIES to another support.
The number of metal/monomer pairs tested so far for electrochemical composite
film formation at the ITIES is very small. The parallel reaction of the precursor metal
ions and the monomers can lead to a composite along the ITIES, hence resulting in
nanoparticle-decorated polymer networks, which may gain a role in catalysis. A
short series of papers is available in this field [78, 83, 84] for tetraoctylammonium
tetrachloroaurate and tyramine dissolved in organic and aqueous phases, respectively.
The direct observation of the particle size distribution confirmed [84] that the mean
particle size can be easily regulated by the Galvani potential difference between the
two liquid phases.
12.3.4 Electrodeposition Near the Solid–Liquid–Liquid
Three-Phase Boundary
Sections 12.2.3–12.4 discussed the nanostructure preparation methods that used no
electrically conducting material under potential control in the vicinity of the liquid–
liquid interface to obtain a nanostructure. In this chapter, various methods are listed
where an electrically conducting plate crosses the ITIES and it is connected as the
working electrode. The reference and the counter electrodes are immersed into the
aqueous phase, and the cell is regulated electrically as a conventional three-electrode
cell. From this point, we shall see a bifurcation depending on which phase contains
the electroactive material and whether the deposition process is an electrochemical
one or it is only electrochemically assisted. The forthcoming discussion will follow
this logical order.
In the studies where a truly electrochemical deposition process takes place
in the vicinity of the three-phase boundary line, the reactant to be reduced is
initially present in the organic phase. In the concept-proofing work [62], the
authors applied HAuCl 4 dissolved in an ionic liquid, 1-decyl-3-methylimidazolium
bis(trifluoromethylsulfonyl)imide. Later, the same technique was applied for toluene
as non-aqueous phase [98], hence inverting the density ratio of the contributing phases