5.5 Thermal Decomposition Method
95
5.5 Thermal Decomposition Method
As a chemical decomposition method, thermal decomposition (also called thermolysis) is caused by heat. The temperature of substance decomposition is
the temperature of chemically decomposing (Dutta et al. 2014). The reactions are
usually endothermic because heat is needed to break chemical bonds in the compound
during decomposition. If decomposition is exothermic enough, a positive feedback
loop can be created, resulting in thermal runaway and possible explosion. Thermal
decomposition method is divided into solid-phase thermal decomposition method,
gas-phase thermal decomposition method, and self-propagation high temperaturesynthesis method (SHS method). The first one is more commonly used in the field
of nanomaterial synthesis so we mainly introduce it in this chapter.
Based on the thermal decomposition and phase transition at elevated temperature, the Cu 4 (SO 4 )(OH) 6 precursor synthesized via a hydrothermal method could be
converted into 3D nanoporous CuO by Yang et al. (2018) CuSO4 · 5H 2 O (0.15 M) and
urea (0.052 M) were dissolved in 50 mL deionized water under magnetic stirring to
prepare a clear solution. Then, blue transparent solution was transferred into 100 mL
Teflon-lined stainless steel autoclave, and subjected to hydrothermal treatment at
90 °C in an electric blast drying oven for 3 h. The precipitates were collected by
centrifugation after cooling down to room temperature, then washed with deionized
water and elthyl alcohol for several times and dried at 60 °C for 12 h. The precursor
was calcined in air at 750 °C for 2 h.
The development of 3D graphene frameworks is usually limited by complex preparation procedure and low specific surface area. Via a facile suitable method including
quick thermal decomposition from sodium chloroacetate, Zhu et al. successfully
synthesized 3D graphene frameworks (GFs) with desired large specific surface area
(up to 1018 m
2 g
−1 ), which is much larger than those of sodium acetate (Zhu et al.
2016). The ruthenium trichloride (RuCl 3 · nH 2 O) and zirconium chloride (ZrCl 4 )
were dissolved in ethanol with the proportion of Ru:Zr = 4:6 to prepare a mixture
of precursor solution. The precursor solution was deposited on one side of the Tisubstrates (the Ti-substrates were pretreated by sand-blasting, etching in 10wt%
boiling oxalic acid for 2 h, then washed with distilled water and finally dried at 80–
100 °C). The samples were annealed at 280, 290, 300, 325, 350, 400, and 450 °C for
10 min, respectively, after evaporation of the solvent. The operation was repeated
until the desired RuO 2 loading (1.0 mg cm
−2 ) was obtained. A final annealing at the
corresponding temperature for 1 h was applied to complete the treatment. The chlorine element in the sodium chloroacetate has a strong induction capacity of in situ
activation, which can regulate the formation of graphene in one step during pyrolysis.
Besides, electrode coatings of 40%RuO 2 –60%ZrO 2 binary oxide were formed on Ti
substrate by thermal decomposition method with the annealing temperature varying
from 280 to 450 °C (from Ma et al. 2017). The XRD and TEM analyses showed that
290 °C was the critical crystallization temperature of RuO 2 .
In addition, Wang et al. had successfully utilized a nanocellulose-assisted low
temperature (lower than 500 °C) thermal treatment method to synthesize reduced
95
5.5 Thermal Decomposition Method
As a chemical decomposition method, thermal decomposition (also called thermolysis) is caused by heat. The temperature of substance decomposition is
the temperature of chemically decomposing (Dutta et al. 2014). The reactions are
usually endothermic because heat is needed to break chemical bonds in the compound
during decomposition. If decomposition is exothermic enough, a positive feedback
loop can be created, resulting in thermal runaway and possible explosion. Thermal
decomposition method is divided into solid-phase thermal decomposition method,
gas-phase thermal decomposition method, and self-propagation high temperaturesynthesis method (SHS method). The first one is more commonly used in the field
of nanomaterial synthesis so we mainly introduce it in this chapter.
Based on the thermal decomposition and phase transition at elevated temperature, the Cu 4 (SO 4 )(OH) 6 precursor synthesized via a hydrothermal method could be
converted into 3D nanoporous CuO by Yang et al. (2018) CuSO4 · 5H 2 O (0.15 M) and
urea (0.052 M) were dissolved in 50 mL deionized water under magnetic stirring to
prepare a clear solution. Then, blue transparent solution was transferred into 100 mL
Teflon-lined stainless steel autoclave, and subjected to hydrothermal treatment at
90 °C in an electric blast drying oven for 3 h. The precipitates were collected by
centrifugation after cooling down to room temperature, then washed with deionized
water and elthyl alcohol for several times and dried at 60 °C for 12 h. The precursor
was calcined in air at 750 °C for 2 h.
The development of 3D graphene frameworks is usually limited by complex preparation procedure and low specific surface area. Via a facile suitable method including
quick thermal decomposition from sodium chloroacetate, Zhu et al. successfully
synthesized 3D graphene frameworks (GFs) with desired large specific surface area
(up to 1018 m
2 g
−1 ), which is much larger than those of sodium acetate (Zhu et al.
2016). The ruthenium trichloride (RuCl 3 · nH 2 O) and zirconium chloride (ZrCl 4 )
were dissolved in ethanol with the proportion of Ru:Zr = 4:6 to prepare a mixture
of precursor solution. The precursor solution was deposited on one side of the Tisubstrates (the Ti-substrates were pretreated by sand-blasting, etching in 10wt%
boiling oxalic acid for 2 h, then washed with distilled water and finally dried at 80–
100 °C). The samples were annealed at 280, 290, 300, 325, 350, 400, and 450 °C for
10 min, respectively, after evaporation of the solvent. The operation was repeated
until the desired RuO 2 loading (1.0 mg cm
−2 ) was obtained. A final annealing at the
corresponding temperature for 1 h was applied to complete the treatment. The chlorine element in the sodium chloroacetate has a strong induction capacity of in situ
activation, which can regulate the formation of graphene in one step during pyrolysis.
Besides, electrode coatings of 40%RuO 2 –60%ZrO 2 binary oxide were formed on Ti
substrate by thermal decomposition method with the annealing temperature varying
from 280 to 450 °C (from Ma et al. 2017). The XRD and TEM analyses showed that
290 °C was the critical crystallization temperature of RuO 2 .
In addition, Wang et al. had successfully utilized a nanocellulose-assisted low
temperature (lower than 500 °C) thermal treatment method to synthesize reduced