3.1 Metal Oxides/Sulfides
37
assemble the reacting species. Moreover, these templates offer advantages in terms of
designing wire-like porous and sphere-like nanostructures. At present, another type
of soft template, i.e., biological templates including DNA, virus particles, bacterium,
etc., has been used to produce unique nanostructures and deposit nanoparticles. SnS
has been an attractive material for Na-ion batteries. Lou et al. have manufactured SnS
nanotubes composed of ultrathin nanosheets by a templating method. In order to boost
the electrochemical property, carbon-coated SnS nanotubes have also been designed
by adding glucose (He et al. 2017). Significantly, the tube-like C/SnS nanostructures
show enhanced sodium storage properties in terms of good rate capability and cycling
performance. 1D hollow construction is of great interest to a wide variety of applications. Many efforts have been devoted to developing technologies for the effective synthesis of different hollow constructions. Among these methods, synthesis
involving templates has been demonstrated to be the most versatile route to generate
different hollow architectures (Lai et al. 2012; Oh and Hyeon 2013). In this regard,
many methods have been developed to manufacture hollow nanostructures with
anisotropic shapes for noble metals, transition metal sulfides, and oxides, based on
various principles, for instance, self-assembly, chemical etching, thermal decomposition, Kirkendall effect, and galvanic replacement, among others (Zhang et al. 2012).
Nevertheless, the development of non-spherical hollow constructions is more challenging on account of the less controllable coating around high-curvature surfaces
and the deficiency of non-spherical templates. Significantly, a hollow 1D Ni x Co 3-x S 4
nanoprisms have been fabricated by sacrificial template process (Yu et al. 2014). The
synthetic strategy for 1D NixCo 3-x S 4 nanoprisms is shown in Fig. 3.1c. Tetragonal
nanoprisms of Co/Ni acetate hydroxide precursors with controllable Co/Ni molar
ratios were first synthesized and used as the sacrificial templates. After a sulfidation process with thioacetamide in ethanol, the solid precursor could be transformed
into the 1D Ni x Co 3-x S 4 prisms with a hollow interior. In FESEM observations, the
inner cavities of highly uniform 1D prisms are elucidated by the sharp contrast
between the edge and the center (Fig. 3.1d). After annealing, polycrystalline hollow
prisms were obtained without apparent deformation in appearance, as revealed by
TEM (Fig. 3.1e) The specific compositional and 1D structural features are beneficial
for electrochemical applications. Additionally, the resultant Ni x Co 3-x S 4 nanoprisms
manifest a high specific capacitance with enhanced cycling stability, making them
potential electrode materials for electrochemical energy storage devices.
3.1.2.1 Block Copolymer Templating
In an alternative route, a series of 1D nanostructures, including core–shell nanorods,
nanotubes, and plain nanorods, has been synthesized with precisely controlled
compositions and dimensions by using functional block copolymers with narrow
molecular weight distributions and specific structures as nanoreactors. The cylindrical nanoreactors enable an ultrahigh degree of control over the shape, surface
chemistry, size, properties, and architecture of 1D nanocrystals. Figure 3.1f illustrates
37
assemble the reacting species. Moreover, these templates offer advantages in terms of
designing wire-like porous and sphere-like nanostructures. At present, another type
of soft template, i.e., biological templates including DNA, virus particles, bacterium,
etc., has been used to produce unique nanostructures and deposit nanoparticles. SnS
has been an attractive material for Na-ion batteries. Lou et al. have manufactured SnS
nanotubes composed of ultrathin nanosheets by a templating method. In order to boost
the electrochemical property, carbon-coated SnS nanotubes have also been designed
by adding glucose (He et al. 2017). Significantly, the tube-like C/SnS nanostructures
show enhanced sodium storage properties in terms of good rate capability and cycling
performance. 1D hollow construction is of great interest to a wide variety of applications. Many efforts have been devoted to developing technologies for the effective synthesis of different hollow constructions. Among these methods, synthesis
involving templates has been demonstrated to be the most versatile route to generate
different hollow architectures (Lai et al. 2012; Oh and Hyeon 2013). In this regard,
many methods have been developed to manufacture hollow nanostructures with
anisotropic shapes for noble metals, transition metal sulfides, and oxides, based on
various principles, for instance, self-assembly, chemical etching, thermal decomposition, Kirkendall effect, and galvanic replacement, among others (Zhang et al. 2012).
Nevertheless, the development of non-spherical hollow constructions is more challenging on account of the less controllable coating around high-curvature surfaces
and the deficiency of non-spherical templates. Significantly, a hollow 1D Ni x Co 3-x S 4
nanoprisms have been fabricated by sacrificial template process (Yu et al. 2014). The
synthetic strategy for 1D NixCo 3-x S 4 nanoprisms is shown in Fig. 3.1c. Tetragonal
nanoprisms of Co/Ni acetate hydroxide precursors with controllable Co/Ni molar
ratios were first synthesized and used as the sacrificial templates. After a sulfidation process with thioacetamide in ethanol, the solid precursor could be transformed
into the 1D Ni x Co 3-x S 4 prisms with a hollow interior. In FESEM observations, the
inner cavities of highly uniform 1D prisms are elucidated by the sharp contrast
between the edge and the center (Fig. 3.1d). After annealing, polycrystalline hollow
prisms were obtained without apparent deformation in appearance, as revealed by
TEM (Fig. 3.1e) The specific compositional and 1D structural features are beneficial
for electrochemical applications. Additionally, the resultant Ni x Co 3-x S 4 nanoprisms
manifest a high specific capacitance with enhanced cycling stability, making them
potential electrode materials for electrochemical energy storage devices.
3.1.2.1 Block Copolymer Templating
In an alternative route, a series of 1D nanostructures, including core–shell nanorods,
nanotubes, and plain nanorods, has been synthesized with precisely controlled
compositions and dimensions by using functional block copolymers with narrow
molecular weight distributions and specific structures as nanoreactors. The cylindrical nanoreactors enable an ultrahigh degree of control over the shape, surface
chemistry, size, properties, and architecture of 1D nanocrystals. Figure 3.1f illustrates