32
3 Synthesis of One-Dimensional Nanomaterials
is placed on strategies employed in fabricating, with examples such as 1D core–shell
architecture, 1D porous architecture, and composite comprising one or more carbon
matrices.
3.1.1 Vapor-Phase Fabrication
3.1.1.1 Chemical Vapor Deposition
Chemical vapor deposition (CVD) is an approach in which a material reacts on special
substrate surfaces or vaporized precursors decompose to form typical 1D solid materials. The precursor material is carried via an inert gas, and the reaction occurs in
a vacuum chamber. If there are chemical reactions involved in the process of vapor
deposition, the approach is called chemical vapor deposition; the converse is physical vapor deposition. Chemical vapor deposition techniques include hot filament,
microwave plasma, atmospheric pressure, thermal, photoassisted, plasma-enhanced,
and low-temperature chemical vapor deposition.
A universal schematic has been reported to show the primary influencing factors
in the catalyst-assisted growth of ZnO nanowires and the formation of vapor–solid
materials. The different influencing factors in the growth of ZnO nanowires have been
discussed in detail. Various parameters, such as reaction gas and carrier flow, substrate
and powder temperature, were presented in the selected shape diagrams (Menzel
et al. 2012). Most importantly, we could identify typical parameter ranges for vapor–
solid growth, film formation and catalyst-assisted vapor–liquid–solid growth using
the shape diagrams. In particular, experiment has also demonstrated the controlled
growth of catalyst-assisted and vapor–solid ZnO nanowires in a chemical vapor
deposition reactor via the carbothermal reduction process based on either downstream
or upstream deposition techniques. In addition, a single-crystalline nanowires have
been synthesized by CVD method (Mudusu et al. 2017). The SnS nanomaterials
grown at temperatures between 600–700 °C have 1D wire-like morphology. The
nanowires have an average diameter of about 12–15 nm with lengths up to several
microns. Furthermore, the SnS nanowires consist of smooth and uniform surfaces.
TEM analysis reveals that the 1D SnS nanowires consist of single-crystalline cubic
crystal construction with a preferential growth direction of <100>.
3.1.1.2 Carbothermal Reduction
Carbothermal reduction is a facile approach for the synthesis of 1D materials, particularly metal oxide-functionalized nanostructures. Various nanomaterials for energy
applications, including LiFePO 4 , MnO 2, and ZnO, have been synthesized by carbothermal reduction. Additionally, this method is compatible with industry because
of its low-cost precursor materials. The oxide reduction mechanism by gaseous
intermediates, such as CO 2 and CO, follows (3.1) and (3.2):
3 Synthesis of One-Dimensional Nanomaterials
is placed on strategies employed in fabricating, with examples such as 1D core–shell
architecture, 1D porous architecture, and composite comprising one or more carbon
matrices.
3.1.1 Vapor-Phase Fabrication
3.1.1.1 Chemical Vapor Deposition
Chemical vapor deposition (CVD) is an approach in which a material reacts on special
substrate surfaces or vaporized precursors decompose to form typical 1D solid materials. The precursor material is carried via an inert gas, and the reaction occurs in
a vacuum chamber. If there are chemical reactions involved in the process of vapor
deposition, the approach is called chemical vapor deposition; the converse is physical vapor deposition. Chemical vapor deposition techniques include hot filament,
microwave plasma, atmospheric pressure, thermal, photoassisted, plasma-enhanced,
and low-temperature chemical vapor deposition.
A universal schematic has been reported to show the primary influencing factors
in the catalyst-assisted growth of ZnO nanowires and the formation of vapor–solid
materials. The different influencing factors in the growth of ZnO nanowires have been
discussed in detail. Various parameters, such as reaction gas and carrier flow, substrate
and powder temperature, were presented in the selected shape diagrams (Menzel
et al. 2012). Most importantly, we could identify typical parameter ranges for vapor–
solid growth, film formation and catalyst-assisted vapor–liquid–solid growth using
the shape diagrams. In particular, experiment has also demonstrated the controlled
growth of catalyst-assisted and vapor–solid ZnO nanowires in a chemical vapor
deposition reactor via the carbothermal reduction process based on either downstream
or upstream deposition techniques. In addition, a single-crystalline nanowires have
been synthesized by CVD method (Mudusu et al. 2017). The SnS nanomaterials
grown at temperatures between 600–700 °C have 1D wire-like morphology. The
nanowires have an average diameter of about 12–15 nm with lengths up to several
microns. Furthermore, the SnS nanowires consist of smooth and uniform surfaces.
TEM analysis reveals that the 1D SnS nanowires consist of single-crystalline cubic
crystal construction with a preferential growth direction of <100>.
3.1.1.2 Carbothermal Reduction
Carbothermal reduction is a facile approach for the synthesis of 1D materials, particularly metal oxide-functionalized nanostructures. Various nanomaterials for energy
applications, including LiFePO 4 , MnO 2, and ZnO, have been synthesized by carbothermal reduction. Additionally, this method is compatible with industry because
of its low-cost precursor materials. The oxide reduction mechanism by gaseous
intermediates, such as CO 2 and CO, follows (3.1) and (3.2):