3.2 Others
47
(1) An aqueous solution with nanosized graphene oxides and polystyrene spheres
dropwise added to surface of nickel foam with micro-sized graphene oxides. (2)
nanosized graphene oxides and polystyrene spheres coated on the surface of microsized graphene oxides after evaporation of water. (3) A solid-state pyrolysis process
at 600 °C for the removal of polystyrene spheres template. (4) A solid-state pyrolysis
process at 800 °C for the removal of polystyrene spheres template and assembly of
nanosized graphene oxides sheets. The block diagram on the right further explained
the formation process of the graphene nanowires. What is more, Fig. 3.3f, g shows
the SEM images of 1D graphene nanowire on graphene foam obtained from different
suspensions with concentrations of 10 and 20 mg mL
−1 . This graphene nanowire on
graphene foam could be used for Na/Li batteries, which shows an excellent rate capability, good reversible capacity, and low discharge-voltage plateau. The outstanding
electrochemical performance is attributed to many lateral exposed pores/edges, high
graphene crystallinity, hierarchical multidimensional graphene construction, and
expansile graphene interlayer distance, which could promote the ion and electron
transport. The 1D graphene assembled by graphene sheets provided new opportunities for energy storage equipment of graphene-based assembly in future. Furthermore,
a zonal porous graphene has been successfully designed by bottom-up approach
(Moreno et al. 2018). This graphene includes an ordered array of pores separated
by ribbons, which could be tuned down to the one nanometer range. The chemical
composition, density, size, and morphology of the pores are defined with atomic
precision by the precise design of the molecular precursors.
3.2.2 Carbon Nanotubes
Carbon nanotubes (CNTs) are allotropes of carbon with a 1D nanostructure. CNTs
have unusual properties, which are valuable for optics, nanotechnology, electronics,
and other fields of materials science. A variety of techniques have been developed to produce CNTs, including high-pressure carbon monoxide disproportionation(HiPCO), laser ablation, arc discharge, CVD, and so on. In these arc discharge,
CVD and laser ablation are batch by batch process. The HiPCO technology is gasphase continuous process. Most of these treating processes take place in a vacuum or
with process gases. The CVD technology is popular, as it has a degree of control over
morphology, length, and diameter. Using particulate catalysts, large quantities of 1D
nanotubes could be synthesized by these processes. But achieving the repeatability
becomes a major problem with CVD growth. Nonetheless, achieving the repeatability becomes a main problem with CVD technology. The HiPCO method has an
advantage in continuous growth and catalysis, which makes CNTs more commercially viable. The HiPCO process helps in producing high purity single-walled carbon
nanotubes in higher quantity. The HiPCO technology helps in producing high purity
single-walled CNTs in higher quantity. The HiPCO reactor operates at a high pressure of 30–50 bar and a high temperature of 900–1100 °C. The carbon source is
carbon monoxide and the catalyst is Ni/Fe penta carbonyl. This catalyst acts as the
47
(1) An aqueous solution with nanosized graphene oxides and polystyrene spheres
dropwise added to surface of nickel foam with micro-sized graphene oxides. (2)
nanosized graphene oxides and polystyrene spheres coated on the surface of microsized graphene oxides after evaporation of water. (3) A solid-state pyrolysis process
at 600 °C for the removal of polystyrene spheres template. (4) A solid-state pyrolysis
process at 800 °C for the removal of polystyrene spheres template and assembly of
nanosized graphene oxides sheets. The block diagram on the right further explained
the formation process of the graphene nanowires. What is more, Fig. 3.3f, g shows
the SEM images of 1D graphene nanowire on graphene foam obtained from different
suspensions with concentrations of 10 and 20 mg mL
−1 . This graphene nanowire on
graphene foam could be used for Na/Li batteries, which shows an excellent rate capability, good reversible capacity, and low discharge-voltage plateau. The outstanding
electrochemical performance is attributed to many lateral exposed pores/edges, high
graphene crystallinity, hierarchical multidimensional graphene construction, and
expansile graphene interlayer distance, which could promote the ion and electron
transport. The 1D graphene assembled by graphene sheets provided new opportunities for energy storage equipment of graphene-based assembly in future. Furthermore,
a zonal porous graphene has been successfully designed by bottom-up approach
(Moreno et al. 2018). This graphene includes an ordered array of pores separated
by ribbons, which could be tuned down to the one nanometer range. The chemical
composition, density, size, and morphology of the pores are defined with atomic
precision by the precise design of the molecular precursors.
3.2.2 Carbon Nanotubes
Carbon nanotubes (CNTs) are allotropes of carbon with a 1D nanostructure. CNTs
have unusual properties, which are valuable for optics, nanotechnology, electronics,
and other fields of materials science. A variety of techniques have been developed to produce CNTs, including high-pressure carbon monoxide disproportionation(HiPCO), laser ablation, arc discharge, CVD, and so on. In these arc discharge,
CVD and laser ablation are batch by batch process. The HiPCO technology is gasphase continuous process. Most of these treating processes take place in a vacuum or
with process gases. The CVD technology is popular, as it has a degree of control over
morphology, length, and diameter. Using particulate catalysts, large quantities of 1D
nanotubes could be synthesized by these processes. But achieving the repeatability
becomes a major problem with CVD growth. Nonetheless, achieving the repeatability becomes a main problem with CVD technology. The HiPCO method has an
advantage in continuous growth and catalysis, which makes CNTs more commercially viable. The HiPCO process helps in producing high purity single-walled carbon
nanotubes in higher quantity. The HiPCO technology helps in producing high purity
single-walled CNTs in higher quantity. The HiPCO reactor operates at a high pressure of 30–50 bar and a high temperature of 900–1100 °C. The carbon source is
carbon monoxide and the catalyst is Ni/Fe penta carbonyl. This catalyst acts as the