Table Of ContentLow Temperature
Chemical
Nanofabrication
Low Temperature
Chemical
Nanofabrication
Recent Progress, Challenges and
Emerging Technologies
OMER NUR
Department of Science and Technology (ITN),
Campus Norrköping, Linköping University,
Norrköping, Sweden
MAGNUS WILLANDER
Department of Science and Technology (ITN),
Campus Norrköping, Linköping University,
Norrköping, Sweden
WilliamAndrewisanimprintofElsevier
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Contents
1. Introduction 1
1.1 Whennanotechnologystarted? 1
1.2 Nanotechnologydrivingforce 5
1.3 Whynanostructures? 8
1.4 Thisbook 10
References 12
2. Phenomenon atthe nanoscale 13
2.1 Whyananomaterialisdifferentfromthebulk? 13
2.2 Electronicbandstructureofnanomaterials 16
2.3 Opticalpropertiesatthenanoscale 23
2.4 Othernanostructuresmorphologyrelatedeffects 36
2.5 Nanodielectriceffects 45
References 46
Furtherreading 48
3. Conventional nanofabricationmethods 49
3.1 Introduction 49
3.2 Mechanicaltechniques 50
3.3 Lithographytechniques 53
3.4 Bottom-upconventionalnanofabricationmethods 69
References 85
Furtherreading 86
4. New emerging nanofabrication methods 87
4.1 Introduction 87
4.2 Emergingtop-downnanostructuresfabricationandimagingtechnologies 88
4.3 Self-assemblyfornanostructuresfabrication 125
4.4 inkjetprintingasatoolfornanofabrication 130
4.5 Electrospinningforfibernanofabrication 132
4.6 Chemicalnanofabricationmethods 137
4.7 Preservingnanostructures 143
References 143
Furtherreading 147
v
vi Contents
5. Low-temperature chemical nanofabricationmethods 149
5.1 Introduction 149
5.2 Thechemicalprecipitationmethod 152
5.3 Low-temperatureaqueouschemicalsynthesisofnanostructures 164
5.4 Theelectrochemicaldeposition 183
5.5 Themicrowave-assistedchemicaldeposition 191
5.6 Solochemicalsynthesisofnanostructures 198
5.7 Polyolchemicalsynthesisofnanostructures 200
5.8 Solvothermalchemicalsynthesis 202
5.9 Successiveionic-layeradsorptionandreaction 204
5.10 Summaryofthelow-temperaturechemicalsynthesisofnanostructures 206
References 207
Furtherreading 211
6. Emerging new applications 213
6.1 Introduction 213
6.2 Emergingsensors 214
6.3 Newsustainableenergyrelatedapplications 223
6.4 Newemergingphotocatalysisapplications 227
6.5 Low-temperaturenanofabrication:challengesandfutureprospects 235
References 236
Index 237
CHAPTER 1
Introduction
1.1 When nanotechnology started?
Although the word “nano” is originally derived from the Greek word
“nânos” meaning a dwarf, the term nanotechnology, which combines the two
words nano and technology, was first introduced in 1974 by the Japanese
scientist Norio Taniguchi of Tokyo Science University [1]. However, about
15 years before that, specifically in December 1959, the Nobel laureate
physicist Richard Feynman described nanotechnology, although not using
the term nanotechnology, during a famous popular speech, “There is Plenty
of Room at the Bottom,” at the annual meeting of the American Physical
Society at Caltech, CA, USA. Feynman had looked two decades ahead and
had envisioned and described the possible potential of manipulating and
controlling matter on a relatively small scale [2]. Specifically Feynman said:
“I would like to describe a field in which little has been done but in which
an enormous amount can be done in principle. The field is not quite the
same as the others in that it will not tell us much of fundamental physics
(in the sense of ‘what are the strange particles?’); but it is more like solid-
state physics in the sense that it might tell us much of great interest about
the strange phenomena that occur in complex situations. Furthermore, a
point that is most important is that it would have an enormous number of
technical applications. What I want to talk about is the problem of manip-
ulating and controlling things on a small scale” [2]. At the time when
Feynman presented his popular visionary talk, there were no spectroscopy
tools that could enable scientists to easily visualize, control, or manipulate
matter at a relatively small scale. It was more than two decades after
Feynman’s suggestion of the new area of physics, that scientists were able
to visualize with high-precision and control/manipulate atoms and clusters.
This was due to the development of the scanning tunneling microscope by
IBM scientists in the 1980s, which allowed high-precision visualization at
scales of the order of the chemical bond length. These experimental ana-
lytical tool developments, combined with advances in theory, and the
modeling of matter, has allowed the potential of nanotechnology to be
seen and its utilization to be within the reach of human capability.
LowTemperatureChemicalNanofabrication ©2020ElsevierInc.
DOI:https://doi.org/10.1016/B978-0-12-813345-3.00001-0 Allrightsreserved. 1
2 LowTemperatureChemicalNanofabrication
Nevertheless, long before this, particularly in the early 1940s, some
research efforts, while working blindly with no imaging/visualization
techniques available, performed the characterization of nanomaterials [3].
In 1944 a paper was published where Fuller characterized nanoscale zinc
oxide material using stereoscopic electron microscopy combined with the
graphical method of crystallographic stereographic projection [3]. In this
pioneering (and long and tedious) work, Fuller came to the conclusion
that the structure he was studying was in fact named a “fourlings struc-
ture” of a few nanometers in size. The fourlings structure of zinc oxide is
a structure with a four-leg arrangement in such a way that the plane
formed by each pair of legs is perpendicular to the other plane formed by
the second pair of the four legs. The reader of this published work will
no doubt see the amount of effort required for Fuller to come to his con-
clusion. In fact such a conclusion can today be reached within a maxi-
mum of 15minutes of investigation using modern imaging spectroscopy
methods, like high-resolution scanning electron microscopy, etc.
The mystery of the change of color of a 1600-year-old Roman goblet
cup has amazed scientists for centuries and was not resolved until 1990. As
seen in Fig. 1.1, the mysterious Lycurgus Cup, which is made of pigmen-
ted glass and decorated with metallic rings, changes color as light is shone
on it. It also shows a different color depending on the direction from
which the person views it. After being thoroughly investigated, scientists
came to the conclusion that the pigmentation is actually made of silver
and gold nanoparticles (NPs) of sizes down to 50nm. This mysterious
chalice which is displayed at the British Museum, London, was fabricated
Figure 1.1 The mysterious 1600-year-old Roman goblet cup which changes color
whenlightisshoneonit.
Introduction 3
using a technique similar to what we use today in nanotechnology. The
change of color is explained by the vibration of metallic NPs as light
falls on them—more details about why nanosized silver and gold have his
ambiguous behavior will be explained in Chapter 2, Phenomenon at the
nanoscale. The Lycurgus chalice which is indeed an “out-of-place artifact”
(OOPArt) has led scientists to consider the Romans as the pioneers of
nanotechnology. But does the search end here? The answer is no!.
Other much older findings discovered only recently have suggested
that nanomatter might have been processed and fabricated by humans
long before the Romans [4]. In 1991 different morphological nanostruc-
tures, e.g., spirals, coils, and shafts, dating back to about 300,000 years,
were found near the banks of Russia’s Kozhim, Narada, and Balbanyu
rivers. These findings were discovered at depths between 10 and 40 feet,
and their geological stratus indicated that they are between 20,000 and
318,000 years old. There has been an argument that suggested that these
tiny objects might have been left from test rockets experiments from a
nearby space research station. Nevertheless, reports have proved that these
tiny objects are too old to have originated from modern manufacturing at
the claimed space station. Further it was also proved that these thousands
of years’ old tiny nanostructures are of technological origin. In 1996 Dr.
E.W. Matvejeva from the Central Scientific Research Department of
Geology and Exploitation of Precious Metals in Moscow wrote that,
despite being thousands of years old, the components are of a technologi-
cal origin. Although this discovery has raised a debate which continues
today, it suggests that an advanced culture with high technological capa-
bilities might have existed during the ancient Pleistocene era [4]. There
are also claims that these tiny nanostructures, which were fabricated using
an advanced technology, do in fact originate from extraterrestrial creatures
who gave them to humans or they may have been discarded by extrater-
restrials. This claim has been stated with no proof apart from the fact that
there was no explanation for the existence of such old technologically
advanced metal nanostructures.
However we can ask the following question: is the findings of the
OOPArts 300,000 years back is the oldest discovered nanomaterials? The
answer is definitely no! According to findings using modern spectroscopy
imaging and characterization tools, nanomaterials and nanostructures
existed long before that, actually since antiquity. Now humans have
learned that nature has always been capable of assembling and creating
self-assembled nanostructures and is adapted to nanoengineering [5]. This
4 LowTemperatureChemicalNanofabrication
implies that nature has been assembling nanostructures from time imme-
morial. To mention some examples, let us consider the structure and
functionality of some natural old existing nanomaterials. Let us consider
the structure and functionality of allophane and smectite which are nanoma-
terials of geological and pedological origin [5].
The allophane structure (see Fig. 1.2) [6] is composed of a hydrous
aluminosilicate group appearing as an irregular hollow spherical NP. The
outer diameter of the allophane is 3.5(cid:1)5.0nm, while the wall thickness
is of the range 0.7(cid:1)1.0nm [8,9]. The allophane as a nanospherical mor-
phology is a pH-dependent clay mineral that has unique characteristics; it
carries both negative and positive charge separated by location in the
nanosphere [7]. The positive charge is originating from the aluminol
group located at the pore region of the nanosphere, while the negative
charge originates from the silanol group located at the inner side of the
allophane nanosphere. Smectite has a unit particle composed of an alumi-
nosilicate layer with sizes ranging from few tenths of a nanometer to a few
hundreds of nanometers, width and length, respectively. The thickness of
the layer is about 1nm only [8]. Due to the relatively small size of both
allophane and smectite, their specific surface area is relatively quite large
(about 700(cid:1)900m2/g); this implies that a teaspoon of allophane will
probably have a surface area much larger than a football playing field [8].
The relatively small size and huge surface area of these naturally occur-
ring materials, that is, allophane and smectite, along with their peculiar
charge characteristics enable them to be excellent contamination sorbent
materials and they are widely employed in industrial applications to
Figure1.2 Freeze-driedsyntheticallophane(A)andtheTEMimagesofthesynthetic
allophane showing the spherical and hollow morphology of allophane (B and C) as
well as allophane nanoaggregates (D). The heat-sensitive allophane was damaged
undertheelectronbeamathighmagnification,buttheconsistentsphericalshapeof
allophaneandthethicknessoftheallophanewall(incircles)areevidentinphotosb
andc,respectively[6].
