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Value-added Synthesis of Graphene: Recycling Industrial Carbon Waste into Electrodes for High-Performance Electronic Devices.

Seo HK, Kim TS, Park C, Xu W, Baek K, Bae SH, Ahn JH, Kim K, Choi HC, Lee TW - Sci Rep (2015)

Bottom Line: We have developed a simple, scalable, transfer-free, ecologically sustainable, value-added method to convert inexpensive coal tar pitch to patterned graphene films directly on device substrates.To demonstrate the practical applications of the graphene films, we used the patterned graphene grown on a dielectric substrate directly as electrodes of bottom-contact pentacene field-effect transistors (max. field effect mobility ~0.36 cm(2)·V(-1)·s(-1)), without using any physical transfer process.This use of a chemical waste product as a solid carbon source instead of commonly used explosive hydrocarbon gas sources for graphene synthesis has the dual benefits of converting the waste to a valuable product, and reducing pollution.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk 790-784, Republic of Korea.

ABSTRACT
We have developed a simple, scalable, transfer-free, ecologically sustainable, value-added method to convert inexpensive coal tar pitch to patterned graphene films directly on device substrates. The method, which does not require an additional transfer process, enables direct growth of graphene films on device substrates in large area. To demonstrate the practical applications of the graphene films, we used the patterned graphene grown on a dielectric substrate directly as electrodes of bottom-contact pentacene field-effect transistors (max. field effect mobility ~0.36 cm(2)·V(-1)·s(-1)), without using any physical transfer process. This use of a chemical waste product as a solid carbon source instead of commonly used explosive hydrocarbon gas sources for graphene synthesis has the dual benefits of converting the waste to a valuable product, and reducing pollution.

No MeSH data available.


Related in: MedlinePlus

Raman spectra of coal tar pitch-derived graphene grown under Ni layer after annealing.(a) Raman spectra of graphene depending on the annealing temperature for 4 min. (b) Raman spectra of graphene depending on the annealing time at 1100 °C. (c) Raman spectra of graphene depending on Ni layer thickness at 1100 °C for 4 min. (d) Raman spectra of graphene depending on the softening point of coal tar pitch at 1100 °C for 4 min. (e) Raman spectra of graphene depending on the concentration of CTP solution at 1100 °C for 4 min. (f) Raman spectra of graphene grown with and without H2 gas. Lines have been shifted vertically for clarity.
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f2: Raman spectra of coal tar pitch-derived graphene grown under Ni layer after annealing.(a) Raman spectra of graphene depending on the annealing temperature for 4 min. (b) Raman spectra of graphene depending on the annealing time at 1100 °C. (c) Raman spectra of graphene depending on Ni layer thickness at 1100 °C for 4 min. (d) Raman spectra of graphene depending on the softening point of coal tar pitch at 1100 °C for 4 min. (e) Raman spectra of graphene depending on the concentration of CTP solution at 1100 °C for 4 min. (f) Raman spectra of graphene grown with and without H2 gas. Lines have been shifted vertically for clarity.

Mentions: In the basic graphene growth process (Fig. 1), CTP (softening point 60.8 °C) was dissolved (8 wt%) in quinoline solvent. Before spin-coating, SiO2 (500 nm)/Si substrates (2 cm × 2 cm) were treated with UV/ozone for 30 min to establish good wetting between CTP solution and substrate, and then a 20-nm thickness of CTP film was deposited on SiO2/Si substrates uniformly by spin coating (6000 rpm, 60 s). The thickness of CTP film was measured using ellipsometry and the film uniformity was confirmed using atomic force microscopy (AFM) (Table S1). A 200-nm-thick Ni metal-capping layer was deposited on top of the CTP film to prevent it from vaporizing and for use as a metal catalyst layer during annealing. The samples were then thermally annealed in a furnace under Ar (50 sccm) and H2 (10 sccm) gas, and low vacuum (~330 mTorr) at 900–1100 °C for 1–4 min to find the optimal conditions for graphene synthesis. After annealing, the samples were cooled to room temperature under the same Ar/H2 flow. A Raman spectroscopy system with excitation of 532 nm was used to evaluate whether CTP films had turned into graphene films5152. To confirm the quality of graphene films formed between Ni capping layer and SiO2/Si substrate in various growth conditions, the Ni layer and the graphene films grown on top of the Ni layer were removed by simple immersion in aqueous FeCl3 solution for 1 min; the underlying graphene films remained on the SiO2/Si substrate. This process enabled direct growth of graphene films on dielectric substrates, and avoided damage to the graphene that could occur if the graphene were transferred using additional transfer process. In the average Raman spectrum (n = 2500 points), the D peak (~1350 cm−1) corresponds to defects in the graphene films. At annealing time of 4 min, the D peak intensity decreased as annealing temperature increased in the range of 900–1100 °C (Fig. 2a). When annealing temperature was 1100 °C, the D peak decreased as annealing time increased from 1 to 4 min (Fig. 2b). The temperature dependence of diffusion is given by:


Value-added Synthesis of Graphene: Recycling Industrial Carbon Waste into Electrodes for High-Performance Electronic Devices.

Seo HK, Kim TS, Park C, Xu W, Baek K, Bae SH, Ahn JH, Kim K, Choi HC, Lee TW - Sci Rep (2015)

Raman spectra of coal tar pitch-derived graphene grown under Ni layer after annealing.(a) Raman spectra of graphene depending on the annealing temperature for 4 min. (b) Raman spectra of graphene depending on the annealing time at 1100 °C. (c) Raman spectra of graphene depending on Ni layer thickness at 1100 °C for 4 min. (d) Raman spectra of graphene depending on the softening point of coal tar pitch at 1100 °C for 4 min. (e) Raman spectra of graphene depending on the concentration of CTP solution at 1100 °C for 4 min. (f) Raman spectra of graphene grown with and without H2 gas. Lines have been shifted vertically for clarity.
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Related In: Results  -  Collection

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f2: Raman spectra of coal tar pitch-derived graphene grown under Ni layer after annealing.(a) Raman spectra of graphene depending on the annealing temperature for 4 min. (b) Raman spectra of graphene depending on the annealing time at 1100 °C. (c) Raman spectra of graphene depending on Ni layer thickness at 1100 °C for 4 min. (d) Raman spectra of graphene depending on the softening point of coal tar pitch at 1100 °C for 4 min. (e) Raman spectra of graphene depending on the concentration of CTP solution at 1100 °C for 4 min. (f) Raman spectra of graphene grown with and without H2 gas. Lines have been shifted vertically for clarity.
Mentions: In the basic graphene growth process (Fig. 1), CTP (softening point 60.8 °C) was dissolved (8 wt%) in quinoline solvent. Before spin-coating, SiO2 (500 nm)/Si substrates (2 cm × 2 cm) were treated with UV/ozone for 30 min to establish good wetting between CTP solution and substrate, and then a 20-nm thickness of CTP film was deposited on SiO2/Si substrates uniformly by spin coating (6000 rpm, 60 s). The thickness of CTP film was measured using ellipsometry and the film uniformity was confirmed using atomic force microscopy (AFM) (Table S1). A 200-nm-thick Ni metal-capping layer was deposited on top of the CTP film to prevent it from vaporizing and for use as a metal catalyst layer during annealing. The samples were then thermally annealed in a furnace under Ar (50 sccm) and H2 (10 sccm) gas, and low vacuum (~330 mTorr) at 900–1100 °C for 1–4 min to find the optimal conditions for graphene synthesis. After annealing, the samples were cooled to room temperature under the same Ar/H2 flow. A Raman spectroscopy system with excitation of 532 nm was used to evaluate whether CTP films had turned into graphene films5152. To confirm the quality of graphene films formed between Ni capping layer and SiO2/Si substrate in various growth conditions, the Ni layer and the graphene films grown on top of the Ni layer were removed by simple immersion in aqueous FeCl3 solution for 1 min; the underlying graphene films remained on the SiO2/Si substrate. This process enabled direct growth of graphene films on dielectric substrates, and avoided damage to the graphene that could occur if the graphene were transferred using additional transfer process. In the average Raman spectrum (n = 2500 points), the D peak (~1350 cm−1) corresponds to defects in the graphene films. At annealing time of 4 min, the D peak intensity decreased as annealing temperature increased in the range of 900–1100 °C (Fig. 2a). When annealing temperature was 1100 °C, the D peak decreased as annealing time increased from 1 to 4 min (Fig. 2b). The temperature dependence of diffusion is given by:

Bottom Line: We have developed a simple, scalable, transfer-free, ecologically sustainable, value-added method to convert inexpensive coal tar pitch to patterned graphene films directly on device substrates.To demonstrate the practical applications of the graphene films, we used the patterned graphene grown on a dielectric substrate directly as electrodes of bottom-contact pentacene field-effect transistors (max. field effect mobility ~0.36 cm(2)·V(-1)·s(-1)), without using any physical transfer process.This use of a chemical waste product as a solid carbon source instead of commonly used explosive hydrocarbon gas sources for graphene synthesis has the dual benefits of converting the waste to a valuable product, and reducing pollution.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk 790-784, Republic of Korea.

ABSTRACT
We have developed a simple, scalable, transfer-free, ecologically sustainable, value-added method to convert inexpensive coal tar pitch to patterned graphene films directly on device substrates. The method, which does not require an additional transfer process, enables direct growth of graphene films on device substrates in large area. To demonstrate the practical applications of the graphene films, we used the patterned graphene grown on a dielectric substrate directly as electrodes of bottom-contact pentacene field-effect transistors (max. field effect mobility ~0.36 cm(2)·V(-1)·s(-1)), without using any physical transfer process. This use of a chemical waste product as a solid carbon source instead of commonly used explosive hydrocarbon gas sources for graphene synthesis has the dual benefits of converting the waste to a valuable product, and reducing pollution.

No MeSH data available.


Related in: MedlinePlus