5.7 Chemical Vapor Deposition Method
101
CVD involves two or more than two kinds of gaseous reactants on the surface of
the matrix, and the products are deposited on the substrate. Since 1980s, CVD technology has been gradually applied to the preparation of powdery, lump, and fibrous
materials.
The preparation of nanomaterials by CVD has many advantages, such as homogeneous particles, high purity, small size, good diversity, high chemical reaction
activity, controllable process, and continuous process.
For example, realization of a highly flexible, lightweight, and high-performance
flexible supercapacitor was achieved using three-dimensional graphene on flexible
graphite-paper. A simple and fast self-assembly approach was utilized for the uniform
deposition of CVD-grown high-quality 3D graphene powders on flexible graphitepaper substrate by Ramadoss et al. (2017). Besides, Wang et al. described one convenient method to fabricate three-dimensional (3D) few-layer graphene/multiwalled
carbon nanotube (MWNT) hybrid nanostructures on industrial grade metal foam
foils (nickel foam) through a one-step ambient pressure chemical vapor deposition (APCVD) process (Wang et al. 2013a, b). Here are the details. 3D few-layer
graphene/MWNT foams were grown through an ambient pressure chemical vapor
deposition (APCVD) method though a mixture of acetylene and hydrogen on 1.0 mm
thick nickel foam, which is typically used as current collector in the battery industry.
Briefly, nickel foam is pretreated with diluted acetic acid and deionized (D.I.) water
to ensure the surface is completely clean and free from oxidation. Next, the nickel
foam is annealed at 800 °C under ambient pressure with the flow of H 2 and Ar for
45 min in order to release the residue stress in the foam, enlarge the average grain
size, and also flatten the surface. After annealing, a mild reactive ion etching (RIE)
O 2 -plasma is used in the annealed nickel foam for 2 min and 2 nm Fe catalyst layer
is deposited on the surface of plasma-treated nickel foam by e-beam evaporation.
The as-prepared nickel foam is loaded into aquartz-tube furnace chamber, heated
to 750 °C under ambient pressure in an Ar/H 2 (200:200 sccm) atmosphere, and
annealed for 5 min. Acetylene is added to stimulate growth of graphene and CNTs
simultaneously on nickel foam frame. After growth, the chamber is cooled to room
temperature at an average cooling rate of 50 °C min
−1 .
Meanwhile, high-porosity MnO 2 materials with mesoporous structure were
prepared by convenient redox reaction, and polypyrrole (PPy) nano-films had been
grown on synthesized mesoporous MnO 2 by chemical vapor deposition, which is
in order to form a 3D nanocomposite structure (Wang et al. 2017a, b). Firstly, the
as-prepared mesoporous MnO 2 powders were immersed into an ethyl alcohol solution containing 5 wt% ferrous chloride at room temperature for 20 min under tenth
atmospheric pressure and then directly dried at 80 °C in atmospheric environment;
as a result, ferrous ions were transformed into ferric ions. Secondly, the sample was
spread out in a culture dish, which was heated to 80 °C in a vacuum chamber. After the
pressure of the vacuum chamber reached one-tenth of the atmospheric pressure, the
vapor of the pyrrole monomer was continuously introduced to the vacuum chamber,
which was maintained at 0.15 atm. Finally, the deposition of PPy thin films lasted
for 20 min to finish the synthesis of PMMO. In addition, Rengaraj et al. presented
a non-enzymatic cholesterol sensor based on a nickel oxide (NiO) and high-quality
101
CVD involves two or more than two kinds of gaseous reactants on the surface of
the matrix, and the products are deposited on the substrate. Since 1980s, CVD technology has been gradually applied to the preparation of powdery, lump, and fibrous
materials.
The preparation of nanomaterials by CVD has many advantages, such as homogeneous particles, high purity, small size, good diversity, high chemical reaction
activity, controllable process, and continuous process.
For example, realization of a highly flexible, lightweight, and high-performance
flexible supercapacitor was achieved using three-dimensional graphene on flexible
graphite-paper. A simple and fast self-assembly approach was utilized for the uniform
deposition of CVD-grown high-quality 3D graphene powders on flexible graphitepaper substrate by Ramadoss et al. (2017). Besides, Wang et al. described one convenient method to fabricate three-dimensional (3D) few-layer graphene/multiwalled
carbon nanotube (MWNT) hybrid nanostructures on industrial grade metal foam
foils (nickel foam) through a one-step ambient pressure chemical vapor deposition (APCVD) process (Wang et al. 2013a, b). Here are the details. 3D few-layer
graphene/MWNT foams were grown through an ambient pressure chemical vapor
deposition (APCVD) method though a mixture of acetylene and hydrogen on 1.0 mm
thick nickel foam, which is typically used as current collector in the battery industry.
Briefly, nickel foam is pretreated with diluted acetic acid and deionized (D.I.) water
to ensure the surface is completely clean and free from oxidation. Next, the nickel
foam is annealed at 800 °C under ambient pressure with the flow of H 2 and Ar for
45 min in order to release the residue stress in the foam, enlarge the average grain
size, and also flatten the surface. After annealing, a mild reactive ion etching (RIE)
O 2 -plasma is used in the annealed nickel foam for 2 min and 2 nm Fe catalyst layer
is deposited on the surface of plasma-treated nickel foam by e-beam evaporation.
The as-prepared nickel foam is loaded into aquartz-tube furnace chamber, heated
to 750 °C under ambient pressure in an Ar/H 2 (200:200 sccm) atmosphere, and
annealed for 5 min. Acetylene is added to stimulate growth of graphene and CNTs
simultaneously on nickel foam frame. After growth, the chamber is cooled to room
temperature at an average cooling rate of 50 °C min
−1 .
Meanwhile, high-porosity MnO 2 materials with mesoporous structure were
prepared by convenient redox reaction, and polypyrrole (PPy) nano-films had been
grown on synthesized mesoporous MnO 2 by chemical vapor deposition, which is
in order to form a 3D nanocomposite structure (Wang et al. 2017a, b). Firstly, the
as-prepared mesoporous MnO 2 powders were immersed into an ethyl alcohol solution containing 5 wt% ferrous chloride at room temperature for 20 min under tenth
atmospheric pressure and then directly dried at 80 °C in atmospheric environment;
as a result, ferrous ions were transformed into ferric ions. Secondly, the sample was
spread out in a culture dish, which was heated to 80 °C in a vacuum chamber. After the
pressure of the vacuum chamber reached one-tenth of the atmospheric pressure, the
vapor of the pyrrole monomer was continuously introduced to the vacuum chamber,
which was maintained at 0.15 atm. Finally, the deposition of PPy thin films lasted
for 20 min to finish the synthesis of PMMO. In addition, Rengaraj et al. presented
a non-enzymatic cholesterol sensor based on a nickel oxide (NiO) and high-quality