40
3 Synthesis of One-Dimensional Nanomaterials
struts. They have been intensively employed as an emerging class of templates
or precursors to construct hollow architectures in the last few years (Zhang et al.
2016; Hu et al. 2016; Cai et al. 2015; Hu and Chen 2014; Zhang et al. 2013; Liu
et al. 2016; Wu et al. 2015). Accordingly, hollow structured MOFs have enabled
the generation of hollow constructions with complexity in the building blocks and
compositions (Chen et al. 2016; Han et al. 2016; Zou et al. 2014). For instance, Zou
and co-workers have been studied the novel hollow octahedra composed of carbon
stabilized ZnO/ZnFe 2 O 4 nanoparticles by hollow MOF-5 as both the precursor and
self-sacrificing template. A surface-energy-driven process may be responsible for
the formation of hollow MOF nanocages. Despite the progress achieved to date, the
construction of nanosized 1D hollow MOFs is still relatively less reported because
of the limited morphologies of the MOF precursors (Zhang et al. 2014a, b; Dai
et al. 2016; Xu et al. 2015; Yang et al. 2015; Avci et al. 2016; Hu et al. 2012; Pang
et al. 2013). Notably, Lou et al. reported the synthesis of 1D CoS 2 hollow prisms
by MOFs using two-step diffusion-controlled method. Uniform zeolitic imidazolate
framework-67 hollow prisms assembled by nanopolyhedra are first synthesized by a
transformation method (Yu et al. 2016). After, the zeolitic imidazolate framework67 building blocks are converted into CoS 2 hollow particles to form the 1D hollow
nanoprisms via a sulfidation process with an additional annealing treatment. Furthermore, the as-obtained CoS 2 nanobubble hollow prisms could be used as an electrode
material for Li-ion batteries, which show remarkable electrochemical performance.
3.1.3 Liquid Phase Synthesis
3.1.3.1 Sol–Gel Method
The sol–gel approach has been generally used to synthesize organic–inorganic hybrid
materials or inorganic nanomaterials. Sol–gel methods include the gel of gelatinized
colloidal solutions and the sol of colloidal solutions in the liquid phase. In the sol–gel
approach, the sol is a colloidal suspension prepared by mixing water with inorganic
metal salts or metal organic compounds. The sol undergoes polymerization and
hydrolysis reactions, converting the liquid sol into a gel with a 3D network. The gel
has a solid skeleton surrounded by an encapsulating liquid phase.
α-MoO 3 nanorods have been fabricated by a facile sol–gel route (Cong et al.
2015). The growth mechanism was controlled by the decomposition rate of citric
acid. Single-crystal and single-phase MoO 3 nanorod arrays were grown in stochastic
directions from a transparent silica glass substrate with a mean length and diameter
of 500 and 10 nm, respectively. Moreover, the decomposition rate of citric acid plays
a significant role in the growth of MoO 3 nanorods, determined from examining the
molar ratio of citric acid and molybdate in the precursor. Additionally, the timing
of citric acid dissociation was controlled by the solvent and by sintering, which
also influences the phase transition and growth of nanorods, as revealed by X-ray
diffraction and SEM. Additionally, the synthetic parameters of the α-MoO 3 nanorod
3 Synthesis of One-Dimensional Nanomaterials
struts. They have been intensively employed as an emerging class of templates
or precursors to construct hollow architectures in the last few years (Zhang et al.
2016; Hu et al. 2016; Cai et al. 2015; Hu and Chen 2014; Zhang et al. 2013; Liu
et al. 2016; Wu et al. 2015). Accordingly, hollow structured MOFs have enabled
the generation of hollow constructions with complexity in the building blocks and
compositions (Chen et al. 2016; Han et al. 2016; Zou et al. 2014). For instance, Zou
and co-workers have been studied the novel hollow octahedra composed of carbon
stabilized ZnO/ZnFe 2 O 4 nanoparticles by hollow MOF-5 as both the precursor and
self-sacrificing template. A surface-energy-driven process may be responsible for
the formation of hollow MOF nanocages. Despite the progress achieved to date, the
construction of nanosized 1D hollow MOFs is still relatively less reported because
of the limited morphologies of the MOF precursors (Zhang et al. 2014a, b; Dai
et al. 2016; Xu et al. 2015; Yang et al. 2015; Avci et al. 2016; Hu et al. 2012; Pang
et al. 2013). Notably, Lou et al. reported the synthesis of 1D CoS 2 hollow prisms
by MOFs using two-step diffusion-controlled method. Uniform zeolitic imidazolate
framework-67 hollow prisms assembled by nanopolyhedra are first synthesized by a
transformation method (Yu et al. 2016). After, the zeolitic imidazolate framework67 building blocks are converted into CoS 2 hollow particles to form the 1D hollow
nanoprisms via a sulfidation process with an additional annealing treatment. Furthermore, the as-obtained CoS 2 nanobubble hollow prisms could be used as an electrode
material for Li-ion batteries, which show remarkable electrochemical performance.
3.1.3 Liquid Phase Synthesis
3.1.3.1 Sol–Gel Method
The sol–gel approach has been generally used to synthesize organic–inorganic hybrid
materials or inorganic nanomaterials. Sol–gel methods include the gel of gelatinized
colloidal solutions and the sol of colloidal solutions in the liquid phase. In the sol–gel
approach, the sol is a colloidal suspension prepared by mixing water with inorganic
metal salts or metal organic compounds. The sol undergoes polymerization and
hydrolysis reactions, converting the liquid sol into a gel with a 3D network. The gel
has a solid skeleton surrounded by an encapsulating liquid phase.
α-MoO 3 nanorods have been fabricated by a facile sol–gel route (Cong et al.
2015). The growth mechanism was controlled by the decomposition rate of citric
acid. Single-crystal and single-phase MoO 3 nanorod arrays were grown in stochastic
directions from a transparent silica glass substrate with a mean length and diameter
of 500 and 10 nm, respectively. Moreover, the decomposition rate of citric acid plays
a significant role in the growth of MoO 3 nanorods, determined from examining the
molar ratio of citric acid and molybdate in the precursor. Additionally, the timing
of citric acid dissociation was controlled by the solvent and by sintering, which
also influences the phase transition and growth of nanorods, as revealed by X-ray
diffraction and SEM. Additionally, the synthetic parameters of the α-MoO 3 nanorod