88
5 Synthesis of Three-Dimensional Nanomaterials
a novel preparation of mesoporous NiCo 2 O 4 -MWCNT nanocomposite aerogels
based on sol-gel technique is proposed (Jayaseelan et al. 2016). Multiwall carbon
nanotube (MWCNT)-supported NiCo 2 O 4 nanocomposite aerogels used as an efficient catalyst for the ethanol electro-oxidation was reported. The MWCNTs exhibit
an interconnected fibrous network with uniform dispersion of NiCo 2 O 4 nanoparticles. The effects of MWCNT concentration on the ethanol electro-oxidation of
MWCNT/NiCo 2 O 4 aerogels are studied. Jayaseelan et al. found that using a proper
loading of MWCNTs allowed it to reach higher current densities for the oxidation
of ethanol in an alkaline media. The highly porous and fibrous MWCNT/NiCo 2 O 4
aerogels are the promising electro-catalysts for the oxidation of a direct ethanol fuel
cell.
5.3 Hydrothermal Method
Since 1982, Hydrothermal Method for the preparation of ultrafine powder by
hydrothermal reaction has attracted the attention of both domestic and foreign countries (Sasikala et al. 2017). At present, it has become one of the most important
methods in preparing nanomaterials in liquid phase. A general term for chemical reactions in fluids, such as water/solution or water vapor, under conditions of high temperature (100 ~ 1000 °C) and high pressure (10 ~ 100 MPa), is Hydrothermal Method.
Through the process of accelerated dialysis and physical control, the improved inorganic materials can be obtained, and then the high purity nanomaterials are got by
filtration, washing, and drying. Water is used as a reaction medium in the reaction
environment of high temperature and high pressure. Water serves as a chemical
composition and participate in reaction. It is both a solvent and a mineralizer. It can
also be used as a medium for pressure transfer, so that usually insoluble or insoluble substances can be dissolved, and the reaction can also be recrystallized. The
general principle of hydrothermal synth plays an important part esis is to ensure that
the reactive materials are in a high reactive state (Jain et al. 2016). The minimum
particle size of ultrafine powders, prepared by hydrothermal method, has reached up
to nanoscale.
Superfine particles appear in UH-Fe 3 O 4 synthesized through the intermediate
of the Fe(II)-ETA complex, hydrolysis and hydrothermal treatment by Wang et al.
in Fig. 5.5A (Wang et al. 2013a, b). The moderate reduction of ETA and ultrasound is of great importance in the synthesis of Fe 3 O 4 particles which have a very
high specific surface area (165.05 m
2 g
−1 ). It is believed that this study is able to
open the way for a new approach to synthesize other metal oxide nanomaterials
for supercapacitor applications with excellent electrochemical performances. Meanwhile, nitrogen-doped graphene has been a hot research topic. Further utilizing the
excellent properties of graphene macroscopic assemblies are crucial. Herein, Chen
et al. first reported an unique and convenient hydrothermal process for controllable
synthesis and structural adjustment of the nitrogen-doped graphene hydrogel (GNGH). By using organic amine and graphene oxide as precursors, readily scaled-up for
5 Synthesis of Three-Dimensional Nanomaterials
a novel preparation of mesoporous NiCo 2 O 4 -MWCNT nanocomposite aerogels
based on sol-gel technique is proposed (Jayaseelan et al. 2016). Multiwall carbon
nanotube (MWCNT)-supported NiCo 2 O 4 nanocomposite aerogels used as an efficient catalyst for the ethanol electro-oxidation was reported. The MWCNTs exhibit
an interconnected fibrous network with uniform dispersion of NiCo 2 O 4 nanoparticles. The effects of MWCNT concentration on the ethanol electro-oxidation of
MWCNT/NiCo 2 O 4 aerogels are studied. Jayaseelan et al. found that using a proper
loading of MWCNTs allowed it to reach higher current densities for the oxidation
of ethanol in an alkaline media. The highly porous and fibrous MWCNT/NiCo 2 O 4
aerogels are the promising electro-catalysts for the oxidation of a direct ethanol fuel
cell.
5.3 Hydrothermal Method
Since 1982, Hydrothermal Method for the preparation of ultrafine powder by
hydrothermal reaction has attracted the attention of both domestic and foreign countries (Sasikala et al. 2017). At present, it has become one of the most important
methods in preparing nanomaterials in liquid phase. A general term for chemical reactions in fluids, such as water/solution or water vapor, under conditions of high temperature (100 ~ 1000 °C) and high pressure (10 ~ 100 MPa), is Hydrothermal Method.
Through the process of accelerated dialysis and physical control, the improved inorganic materials can be obtained, and then the high purity nanomaterials are got by
filtration, washing, and drying. Water is used as a reaction medium in the reaction
environment of high temperature and high pressure. Water serves as a chemical
composition and participate in reaction. It is both a solvent and a mineralizer. It can
also be used as a medium for pressure transfer, so that usually insoluble or insoluble substances can be dissolved, and the reaction can also be recrystallized. The
general principle of hydrothermal synth plays an important part esis is to ensure that
the reactive materials are in a high reactive state (Jain et al. 2016). The minimum
particle size of ultrafine powders, prepared by hydrothermal method, has reached up
to nanoscale.
Superfine particles appear in UH-Fe 3 O 4 synthesized through the intermediate
of the Fe(II)-ETA complex, hydrolysis and hydrothermal treatment by Wang et al.
in Fig. 5.5A (Wang et al. 2013a, b). The moderate reduction of ETA and ultrasound is of great importance in the synthesis of Fe 3 O 4 particles which have a very
high specific surface area (165.05 m
2 g
−1 ). It is believed that this study is able to
open the way for a new approach to synthesize other metal oxide nanomaterials
for supercapacitor applications with excellent electrochemical performances. Meanwhile, nitrogen-doped graphene has been a hot research topic. Further utilizing the
excellent properties of graphene macroscopic assemblies are crucial. Herein, Chen
et al. first reported an unique and convenient hydrothermal process for controllable
synthesis and structural adjustment of the nitrogen-doped graphene hydrogel (GNGH). By using organic amine and graphene oxide as precursors, readily scaled-up for