12.3 Deposition at the Liquid–Liquid Interface
453
film shows rather an open-pore structure as opposed to the dense filament array
shown for the metal films. The proper choice of the organic solvent and the decrease
in temperature improves the film smoothness at the ITIES side [90].
The D3PIE method was also adopted for interfaces where carbon nanotubes were
accumulated. The current increase rate for constant-potential polymerization is much
faster for the interface already covered with electrically conducting nanowires since
the interconnections formed between the nanowires by the in situ growing polymer
yield a faster expansion of the eclectically connected area than in the absence of the
nanowires [65]. The conclusion of the latter study was that at first, the surface of the
nanowires is covered with the polymer, and the growth of the polymer towards the
monomer-containing organic phase starts only thereafter. Nevertheless, the evolution
of the morphological features after the full coverage of the nanowire network is
identical to that of the simple D3PIE-prepared samples, which is rationalized by
the same processes taking place after the growth of the reaction front beyond the
nanotube network [65].
12.4 Deposition with the Help of Tips
12.4.1 Deposition of Microcolumns by Using Microtips
Manufacturing of micropillars by using microtips [105–114] is a method related to
the family of localized electrochemical deposition (LECD) techniques. Although the
technique of obtaining micropillars of about 10 micrometre minimum width will not
directly lead us to the preparation techniques of nanoscale object, it is didactically
important to shortly discuss its experimental conditions and limitations for getting
a complete view on all related techniques, in particular for the sake of comparison
with nanopipette-based methods to be shown in Sect. 12.4.3.
The basis of this technique is that a conducting substrate is used as working
electrode that will later host the micropillar. The solution used is a conventional
plating bath with relatively large metal salt concentration and also with various
deposition-regulating components. The anode is a microtip made of a noble metal
(e.g., Pt) that does not serve as a source of the reactant for the deposition. Instead,
the reaction at the anode (counter electrode) is the decomposition of the solvent
(e.g., oxygen evolution in aqueous solutions). The diameter of the counter electrode
is a few tens of micrometres. The active surface is the bottom-facing microdisc
with the sides of the electrode being sealed. Reference electrode is seldom applied
in microcolumn-preparation setups [106, 114]; and if so, it is an indicator electrode
only but is not a part of the regulation circuit of either the working electrode potential
or the cell voltage. The cells are operated with a cell voltage of a few volts.
One of the key parameters in the microcolumn formation is the distance between
the substrate and the anode. The interelectrode distance is comparable to the diameter of the anode disc. This distance is much larger than the Debye length of the
453
film shows rather an open-pore structure as opposed to the dense filament array
shown for the metal films. The proper choice of the organic solvent and the decrease
in temperature improves the film smoothness at the ITIES side [90].
The D3PIE method was also adopted for interfaces where carbon nanotubes were
accumulated. The current increase rate for constant-potential polymerization is much
faster for the interface already covered with electrically conducting nanowires since
the interconnections formed between the nanowires by the in situ growing polymer
yield a faster expansion of the eclectically connected area than in the absence of the
nanowires [65]. The conclusion of the latter study was that at first, the surface of the
nanowires is covered with the polymer, and the growth of the polymer towards the
monomer-containing organic phase starts only thereafter. Nevertheless, the evolution
of the morphological features after the full coverage of the nanowire network is
identical to that of the simple D3PIE-prepared samples, which is rationalized by
the same processes taking place after the growth of the reaction front beyond the
nanotube network [65].
12.4 Deposition with the Help of Tips
12.4.1 Deposition of Microcolumns by Using Microtips
Manufacturing of micropillars by using microtips [105–114] is a method related to
the family of localized electrochemical deposition (LECD) techniques. Although the
technique of obtaining micropillars of about 10 micrometre minimum width will not
directly lead us to the preparation techniques of nanoscale object, it is didactically
important to shortly discuss its experimental conditions and limitations for getting
a complete view on all related techniques, in particular for the sake of comparison
with nanopipette-based methods to be shown in Sect. 12.4.3.
The basis of this technique is that a conducting substrate is used as working
electrode that will later host the micropillar. The solution used is a conventional
plating bath with relatively large metal salt concentration and also with various
deposition-regulating components. The anode is a microtip made of a noble metal
(e.g., Pt) that does not serve as a source of the reactant for the deposition. Instead,
the reaction at the anode (counter electrode) is the decomposition of the solvent
(e.g., oxygen evolution in aqueous solutions). The diameter of the counter electrode
is a few tens of micrometres. The active surface is the bottom-facing microdisc
with the sides of the electrode being sealed. Reference electrode is seldom applied
in microcolumn-preparation setups [106, 114]; and if so, it is an indicator electrode
only but is not a part of the regulation circuit of either the working electrode potential
or the cell voltage. The cells are operated with a cell voltage of a few volts.
One of the key parameters in the microcolumn formation is the distance between
the substrate and the anode. The interelectrode distance is comparable to the diameter of the anode disc. This distance is much larger than the Debye length of the