100408 no.04-hydrothermal synthesis of nanomaterials-guo(1)
TRANSCRIPT
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
1/22
Hydrothermal /Hydrothermal / SolvothermalSolvothermal
Synthesis ofSynthesis of NanomaterialsNanomaterials
YuYu--GuoGuo GuoGuo
2010.4.82010.4.8
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
2/22
Hydrothermal /Hydrothermal /SolvothermalSolvothermal Synthesis ofSynthesis of
NanomaterialsNanomaterials
ContentContent
What is hydrothermal /What is hydrothermal /solvothermalsolvothermal synthesis?synthesis?
What is the main characteristics ofWhat is the main characteristics of
hydrothermal /hydrothermal /solvothermalsolvothermal synthesis?synthesis? Examples of synthesis ofExamples of synthesis ofnanomaterialsnanomaterials viavia
hydrothermal /hydrothermal /solvothermalsolvothermal methodmethod
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
3/22
Introduction to hydrothermalIntroduction to hydrothermal
techniquestechniques
The hydrothermal technique has been most popular,
garnering interest from scientists and technologists ofdifferent disciplines, particularly in the last fifteen
years. The term hydrothermal is purely of geological
origin. It was first used by the British Geologist, SirRoderick Murchison (17921871), to describe the
action of water at elevated temperature and pressure
in bringing about changes in the earths crust leadingto the formation of various rocks and minerals.
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
4/22
Introduction to hydrothermalIntroduction to hydrothermal
techniquestechniquesThe hydrothermal synthesis has been successful for
the preparation of important solids such asmicroporous crystals, superionic conductors,
chemical sensing oxides, electronically conducting
solids, complex oxide ceramics and fluorides,magnetic materials, and luminescence phosphors. It
is also a route to unique condensed materials
including nanometer particles, gels, thin films,distinguished helical and chiral structures, and
particularly-stacking-sequence materials.
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
5/22
What is hydrothermal /What is hydrothermal /solvothermalsolvothermal
synthesis?synthesis?
Hydrothermal synthesis refers to the synthesis by chemical
reactions of substances in a sealed heated solution aboveambient temperature and pressure.
Solvothermal synthesis route was first proposed by Yi-Tai
Qian in 1996 (University of Science and Technology of
China), and is very similar to the hydrothermal route, the
only difference is the precursor solution is usually non-
aqueous but this is not always the case in all literature uses
of the expression.
Xie Y Qian YT*Wang WZ Zhang SYand Zhang YH A benzene-thermal synthetic route to nanocrystalline GaNSCIENCE, 272,1996, 1926
30nm
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
6/22
Apparatus in hydrothemal synthesis
autoclave
for cook
autoclave
formedicine
autoclave for
hydrothermal
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
7/22
Apparatus in hydrothemal synthesisThe autoclaves used in hydrothermal are usually thick-walledsteel cylinders with a hermetic seal which must withstand hightemperatures and pressures for prolonged periods of time.
Furthermore, the autoclave material must be inert with respectto the solvent. The closure is the most important element of theautoclave.
Many designs have been developed for seals, the most famous
being the Bridgman seal.In most cases steel-corroding solutions are used in hydrothermalexperiments. To prevent corrosion of the internal cavity of theautoclave, protective inserts are generally used. These may havethe same shape of the autoclave and fit in the internal cavity
(contact-type insert) or be a "floating" type insert which occupiesonly part of the autoclave interior. Inserts may be made ofcarbon-free iron, copper, silver, gold, platinum, titanium, glass (orquartz), or Teflon, depending on the temperature and solutionused.
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
8/22
Apparatus in hydrothemal synthesis
Commercially available autoclaves. (Courtesy of
M/S/ Toshin Kogyo Co. Ltd., Japan.)
Commercially available autoclaves. (Photo courtesy
of Parr Instruments Co., Illinois, USA.)
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
9/22
Schematic diagram of the
autoclave used in
hydrothermal / solvothermal
synthesis (1) stainless steel
autoclave (2) precursor
solution (3) Teflon liner (4)stainless steel lid (5) spring
autoclave used in my group
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
10/22
autoclave used inmy group
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
11/22
autoclave used in
my group
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
12/22
Characteristics ofCharacteristics of hydrothermal
synthesis
Generally, the hydrothermal synthesis involvesGenerally, the hydrothermal synthesis involves
with the following two major characteristics:with the following two major characteristics:
1) The system is always at a1) The system is always at a nonnon--idealideal andand nonnon--
equilibriumequilibrium state;state;2) The solvent is always at its2) The solvent is always at its nearnear--criticalcritical,,
criticalcritical oror supercritical statesupercritical state..
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
13/22
Characteristics ofCharacteristics of hydrothermal
synthesis
Advantages of hydrothermal / solvothermal synthesis:
1) Most material can be made soluble in proper solvent by heating and
pressuring the system close to its critical point;2) Significant improvement in the chemical activity of the reactant, the
possibility to replace the solid-state synthesis, and materials whichmay not be obtained via solid-state reaction may be preparedthrough hydrothermal / solvothermal synthesis;
3) Products ofintermediate state, metasable state and specific phasemay be easily produced, novel compounds of metastable state andother specific condensed state may be synthesized;
4) Easy and precise control of the size, shape distribution, crystallinity
of the final product through adjusting the parameters such asreaction temperature, reaction time, solvent type, surfactant type,precursor type an the like.
5) Substances which are low in melting-points, high in vapor pressuresand tend to go pyrolysis will be obtained.
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
14/22
Characteristics ofCharacteristics of hydrothermal
synthesis
Disadvantages of hydrothermal / solvothermal
synthesis:
1) The need of expensive autoclaves;1) The need of expensive autoclaves;
2) Safety issues during the reaction process;2) Safety issues during the reaction process;3) Impossibility of observing the reaction3) Impossibility of observing the reaction
process (process (black boxblack box))
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
15/22
Applications of hydrothermal synthesisApplications of hydrothermal synthesis
in the preparation ofin the preparation ofnanomaterialsnanomaterials
The hydrothermal method has been firstly proposedThe hydrothermal method has been firstly proposed
toto simulatesimulate the genetic condition of geologicalthe genetic condition of geologicalminerals;minerals;
Later, it has been adopted in the synthesis ofLater, it has been adopted in the synthesis ofmolecular sievesmolecular sieves and the crystal growth;and the crystal growth;
Now, with different starting materials, solvents,Now, with different starting materials, solvents,reaction temperatures as well as other experimentalreaction temperatures as well as other experimentalparameters, people have reported the synthesis ofparameters, people have reported the synthesis of
various kinds of nanostructures through hydrothermalvarious kinds of nanostructures through hydrothermal//solvothermalsolvothermal approaches includingapproaches including metal oxidesmetal oxides,,carbonaceouscarbonaceous nanostructures and etc.nanostructures and etc.
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
16/22
Applications of hydrothermal synthesisApplications of hydrothermal synthesis
in the preparation ofin the preparation ofnanomaterialsnanomaterials
Hydrothermal /Hydrothermal /solvothermalsolvothermal synthesis ofsynthesis of
zeoliteszeolites Hydrothermal /Hydrothermal /solvothermalsolvothermal synthesis ofsynthesis of
metal oxidesmetal oxides
Hydrothermal /Hydrothermal /solvothermalsolvothermal synthesis ofsynthesis ofcarbonaceous materialcarbonaceous material
Hydrothermal /Hydrothermal /
solvothermalsolvothermal
synthesis ofsynthesis of
nanowiresnanowires
OtherOther strategiesstrategies for hydrothermal /for hydrothermal /
solvothermalsolvothermal synthesissynthesis
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
17/22
Hydrothermal /Hydrothermal /solvothermalsolvothermal synthesissynthesis
ofofzeoliteszeolites
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
18/22
Hydrothermal /Hydrothermal /solvothermalsolvothermal
synthesis ofsynthesis ofzeoliteszeolites Zeolites are microporous crystalline materials that have been the most widely used
catalysts in industrial processes such as oil refining and petrochemistry. Theextension of their sole micropores into hierarchical pore systems consisting of bothmicropores and mesopores is nowadays demanded specifically for catalyzing largemolecules having dimensions in the mesoporous region (2-50 nm). Suchhierarchically porous zeolites or mesoporous materials with zeolitic characteristicsare known to solve the phenomena of slow diffusion and coke formation, resultingin pore blockage and catalyst deactivation, that are often encountered during theheterogeneous catalytic reactions of bulky molecules.
There are 46 known zeolite minerals in nature and over 175 synthetic zeolitesknown in the literature. The number of synthetic zeolites is increasing day by day,particularly after the discovery of aluminophosphate zeolites by Wilson et al.(1982). Despite the remarkable structural diversity in aluminophosphate zeolites,the product compositions are very similar:
xR + Al2O3 + (1.00.2) P2O5 + yH2O
whereR is an amine or quaternary ammonium ion.
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
19/22
Hydrothermal /Hydrothermal /solvothermalsolvothermal
synthesis ofsynthesis ofzeoliteszeolitesMicroporous Zeolite-Type Materials Basic structure of zeolite framework
Breck, D. W.,
ZeoliteMolecular
Sieves: Structure,
Chemistry and
Use, Wiley &
Sons, London
(1974)
Breck, D. W.,
Structure of
Zeolite, in:Zeolite
Molecular Sieves,
pp. 29185,
Wiley
Interscience
Publication, NewYork (1974)
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
20/22
Hydrothermal /Hydrothermal /solvothermalsolvothermal
synthesis ofsynthesis ofzeoliteszeolites The mechanisms of zeolite formation are very complex due to
the plethora of chemical reactions, equilibria, and solubility
variations that occur through the heterogeneous synthesismixture during the crystallization process.
Generally, the hydrothermal synthesis of zeolites involvesseveral steps, as shown below:
Reactant
Reactant mixtures
Nucleation
Crystal Growth
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
21/22
Hydrothermal /Hydrothermal /solvothermalsolvothermal
synthesis ofsynthesis ofzeoliteszeolites
For example, by using trialkoxysilylated alkyl
poly(oxyethylene ether) as mesopore-directingagent, a hierarchically porous siliceous MFI
zeolite (silicalite-1) with narrow mesoporosity
has been hydrothermally synthesized. A
mesostructured silica-surfactant composite was
formed at the early stage of the reaction, andzeolite crystallization proceeded during
subsequent hydrothermal treatment.
Rino R. Mukti et al,Langmuir2010, 26(4), 27312735
-
8/2/2019 100408 No.04-Hydrothermal Synthesis of Nanomaterials-GUO(1)
22/22
Hydrothermal /Hydrothermal /solvothermalsolvothermal
synthesis ofsynthesis ofzeoliteszeolites
SEM images of
mesoporous silicalite-1after hydrothermal
synthesis for (a) 2 days
and (b) 3 days. The
images for the (c)
product prepared with
C16EO10 and (d)
conventional silicalite-1
after hydrothermal
synthesis for 2 days arealso shown for
comparison.
Rino R. Mukti et al,Langmuir2010, 26(4), 27312735