5.3 Hydrothermal Method
89
Fig. 5.5 A Preparation of routes toward a UH-Fe 3 O 4 , b H-Fe 3 O 4 , and c H-Fe 2 O 3 . Reprinted from
Ref. Wang et al. (2013a, b), copyright 2013, with permission from The Royal Society of Chemistry.
B SEM images of the precursor obtained with the assistance of 12 mmol NH4F at various reaction
stages by setting the reaction time to a 0.5 h, b 1.5 h, c 2.5 h, d 3.5 h; e scheme of the products
at various reaction stages; f–i SEM images of the products obtained at different concentration
of NH4F. j–m Morphologies of the precursor at different reaction times without adding NH4F;
n proposed mechanism for the effect of NH4F on morphology construction. Reprinted from Ref.
Chen et al. (2013a, b), copyright 2015, with permission from The Royal Society of Chemistry
mass production of nitrogen-doped graphene hydrogel can be obtained (Chen et al.
2013a, b). The organic amine is not only as nitrogen sources to obtain the nitrogendoped graphene but also as an important modification to control the assembly of
graphene sheets in the 3D structures. Inner structure of the GN-GHs and the content
of nitrogen in the graphene are easily adjusted by organic amine. As you can see, the
supercapacitor performance of the typical product could be remarkably enhanced in
this way. In addition, large-scale production of three-dimensional (3D) hierarchical
porous nickel cobaltate nanowire cluster arrays, derived from nanosheet arrays with
robust adhesion on Ni foam, were successfully prepared by a simple hydrothermal
method by Chen et al. in Fig. 5.5B (Chen et al. 2013a, b). On the basis of the
morphology evolution upon reaction time, a possible formation process is reported.
The role of NH 4 F in formation of the structure has also been investigated on the
basis of different NH 4 F amounts. This unique structure significantly enhances the
electroactive surface areas of the NiCo 2 O 4 arrays, which brings out better interfacial/chemical distributions at the nanoscale, fast ion, electron transfer as well as good
strain accommodation.
Furthermore, Wang et al. developed a supercapacitor electrode in composition
with 3D self-supported Co 3 O 4 @CoMoO 4 core-shell architectures which are directly
grown on nickel foam (Wang et al. 2016). Co 3 O 4 nanocones were grown vertically
on the nickel foam as the core and CoMoO 4 nanosheets were further engineered to
immobilized on the surface of the nanocones as the shell. The unique architecture
takes advantage of a large interfacial area, numerous channels for rapid diffusion
of electrolyte ions, fast electron transport, and the high electrochemical activity
89
Fig. 5.5 A Preparation of routes toward a UH-Fe 3 O 4 , b H-Fe 3 O 4 , and c H-Fe 2 O 3 . Reprinted from
Ref. Wang et al. (2013a, b), copyright 2013, with permission from The Royal Society of Chemistry.
B SEM images of the precursor obtained with the assistance of 12 mmol NH4F at various reaction
stages by setting the reaction time to a 0.5 h, b 1.5 h, c 2.5 h, d 3.5 h; e scheme of the products
at various reaction stages; f–i SEM images of the products obtained at different concentration
of NH4F. j–m Morphologies of the precursor at different reaction times without adding NH4F;
n proposed mechanism for the effect of NH4F on morphology construction. Reprinted from Ref.
Chen et al. (2013a, b), copyright 2015, with permission from The Royal Society of Chemistry
mass production of nitrogen-doped graphene hydrogel can be obtained (Chen et al.
2013a, b). The organic amine is not only as nitrogen sources to obtain the nitrogendoped graphene but also as an important modification to control the assembly of
graphene sheets in the 3D structures. Inner structure of the GN-GHs and the content
of nitrogen in the graphene are easily adjusted by organic amine. As you can see, the
supercapacitor performance of the typical product could be remarkably enhanced in
this way. In addition, large-scale production of three-dimensional (3D) hierarchical
porous nickel cobaltate nanowire cluster arrays, derived from nanosheet arrays with
robust adhesion on Ni foam, were successfully prepared by a simple hydrothermal
method by Chen et al. in Fig. 5.5B (Chen et al. 2013a, b). On the basis of the
morphology evolution upon reaction time, a possible formation process is reported.
The role of NH 4 F in formation of the structure has also been investigated on the
basis of different NH 4 F amounts. This unique structure significantly enhances the
electroactive surface areas of the NiCo 2 O 4 arrays, which brings out better interfacial/chemical distributions at the nanoscale, fast ion, electron transfer as well as good
strain accommodation.
Furthermore, Wang et al. developed a supercapacitor electrode in composition
with 3D self-supported Co 3 O 4 @CoMoO 4 core-shell architectures which are directly
grown on nickel foam (Wang et al. 2016). Co 3 O 4 nanocones were grown vertically
on the nickel foam as the core and CoMoO 4 nanosheets were further engineered to
immobilized on the surface of the nanocones as the shell. The unique architecture
takes advantage of a large interfacial area, numerous channels for rapid diffusion
of electrolyte ions, fast electron transport, and the high electrochemical activity