44
3 Synthesis of One-Dimensional Nanomaterials
used to make separators, which can enhance the rate and safety capabilities of lithiumion batteries. The approach allows low-cost scalable synthesis of 1D nanomaterials
and membranes.
3.1.4.2 Lithographically Patterned Method
Lithographic approaches include dip-pen nanolithography, electron-beam lithography, and focused ion beam lithography and have been exploited to fabricate
designed-geometry patterns on typical solid substrates. These techniques have many
advantages including the fabrication of well-aligned and large-scale nanometer
arrays. Nevertheless, the low throughput and high cost of large-scale nanostructures
remain challenges.
Au/MnO 2 core–shell nanowires have been fabricated by a lithographically
patterned nanowire electrodeposition process (Yan et al. 2012). The linear Au
nanowire core and hemicylindrical MnO 2 shell were prepared on glass. The rectangular cross section of the Au nanowires showed a height, width, and length of
approximately 40 nm, 200 nm, and 1–10 mm, respectively. Subsequently, MnO 2 was
deposited on the Au nanowires by a potentiostatic electrooxidation process from a
manganese ion solution, forming a hemicylindrical and conformal shell structure with
a diameter of approximately 50–300 nm. The shell of MnO 2 was mesoporous and
in the δ-phase, as revealed by Raman spectroscopy and X-ray diffraction. Moreover,
TEM analysis showed that the δ-phase MnO 2 shell was composed of a mesoporous
net-like structure with 2 nm fibrils. This mesoporous MnO 2 shell structure had a
thickness of 68 ± 3 nm. Moreover, the specific capacitance of the Au/MnO 2 core–
shell nanowire array was measured by cyclic voltammetry (CV). The Au/MnO 2 core–
shell nanostructure showed a good specific capacitance and stable cycling in aqueous
electrolyte. Furthermore, the Au/MnO 2 core–shell nanowires showed hybrid energy
storage by the deconvolution of specific capacitance into non-insertion and insertion
components. Additionally, a symmetrical capacitor consisting of horizontal, interleaved MnO 2 /Au nanowires has been described (Yan et al. 2014). All 750 nanowires
in the capacitor had a length of 2.5 mm and consisted of an Au nanowire core
(approximately 40 × 200 nm) and a δ-phase MnO 2 shell (thickness of approximately 60–220 nm). The Au/MnO 2 core–shell nanowires were patterned onto the
surface of a glass substrate by lithographically patterned nanowire electrodeposition.
3.1.4.3 Electrospinning
Electrospinning is a large-scale and cost-effective technique for manufacturing 1D
nanofibers. Electrospinning uses spinning force and electric fields to eject liquid
precursor materials via a fine orifice to typically form fibrous nanostructures (Ren
et al. 2015).
At present, a range of practical fabrication techniques, such as hydrothermal
synthesis, chemical vapor deposition, physical vapor deposition, electrochemical
3 Synthesis of One-Dimensional Nanomaterials
used to make separators, which can enhance the rate and safety capabilities of lithiumion batteries. The approach allows low-cost scalable synthesis of 1D nanomaterials
and membranes.
3.1.4.2 Lithographically Patterned Method
Lithographic approaches include dip-pen nanolithography, electron-beam lithography, and focused ion beam lithography and have been exploited to fabricate
designed-geometry patterns on typical solid substrates. These techniques have many
advantages including the fabrication of well-aligned and large-scale nanometer
arrays. Nevertheless, the low throughput and high cost of large-scale nanostructures
remain challenges.
Au/MnO 2 core–shell nanowires have been fabricated by a lithographically
patterned nanowire electrodeposition process (Yan et al. 2012). The linear Au
nanowire core and hemicylindrical MnO 2 shell were prepared on glass. The rectangular cross section of the Au nanowires showed a height, width, and length of
approximately 40 nm, 200 nm, and 1–10 mm, respectively. Subsequently, MnO 2 was
deposited on the Au nanowires by a potentiostatic electrooxidation process from a
manganese ion solution, forming a hemicylindrical and conformal shell structure with
a diameter of approximately 50–300 nm. The shell of MnO 2 was mesoporous and
in the δ-phase, as revealed by Raman spectroscopy and X-ray diffraction. Moreover,
TEM analysis showed that the δ-phase MnO 2 shell was composed of a mesoporous
net-like structure with 2 nm fibrils. This mesoporous MnO 2 shell structure had a
thickness of 68 ± 3 nm. Moreover, the specific capacitance of the Au/MnO 2 core–
shell nanowire array was measured by cyclic voltammetry (CV). The Au/MnO 2 core–
shell nanostructure showed a good specific capacitance and stable cycling in aqueous
electrolyte. Furthermore, the Au/MnO 2 core–shell nanowires showed hybrid energy
storage by the deconvolution of specific capacitance into non-insertion and insertion
components. Additionally, a symmetrical capacitor consisting of horizontal, interleaved MnO 2 /Au nanowires has been described (Yan et al. 2014). All 750 nanowires
in the capacitor had a length of 2.5 mm and consisted of an Au nanowire core
(approximately 40 × 200 nm) and a δ-phase MnO 2 shell (thickness of approximately 60–220 nm). The Au/MnO 2 core–shell nanowires were patterned onto the
surface of a glass substrate by lithographically patterned nanowire electrodeposition.
3.1.4.3 Electrospinning
Electrospinning is a large-scale and cost-effective technique for manufacturing 1D
nanofibers. Electrospinning uses spinning force and electric fields to eject liquid
precursor materials via a fine orifice to typically form fibrous nanostructures (Ren
et al. 2015).
At present, a range of practical fabrication techniques, such as hydrothermal
synthesis, chemical vapor deposition, physical vapor deposition, electrochemical