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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.


(a) Average Raman spectrum (2500 points) of coal tar pitch-derived graphene grown under Ni layer. (b) Raman mapping (100 × 100 μm) of D-to-G band peak intensity ratio (ID/IG) in coal tar pitch-derived graphene grown on Ni layer. Scale bar: 20 μm. (c) Raman mapping of 2D-to-G band peak intensity ratio (I2D/IG) in coal tar pitch-derived graphene grown on Ni layer. Scale bar: 20 μm. (d) Raman spectra of mono-layer to few-layer graphene formed on the SiO2/Si substrates that exists in the mapping area. (between Ni layer and SiO2/Si substrate). Lines have been shifted vertically for clarity. (e) TEM images of graphene films at the folded edge (f) TEM image of graphene surface. Inset: hexagonal electron diffraction pattern of graphene films.
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f3: (a) Average Raman spectrum (2500 points) of coal tar pitch-derived graphene grown under Ni layer. (b) Raman mapping (100 × 100 μm) of D-to-G band peak intensity ratio (ID/IG) in coal tar pitch-derived graphene grown on Ni layer. Scale bar: 20 μm. (c) Raman mapping of 2D-to-G band peak intensity ratio (I2D/IG) in coal tar pitch-derived graphene grown on Ni layer. Scale bar: 20 μm. (d) Raman spectra of mono-layer to few-layer graphene formed on the SiO2/Si substrates that exists in the mapping area. (between Ni layer and SiO2/Si substrate). Lines have been shifted vertically for clarity. (e) TEM images of graphene films at the folded edge (f) TEM image of graphene surface. Inset: hexagonal electron diffraction pattern of graphene films.

Mentions: CTP-derived graphene films grown on the SiO2/Si substrates at 1100 °C for 4 min were prepared for use in further characterization. This annealing condition was chosen based on the results of preliminary trials. In the Raman scanning over a large area (100 × 100 μm, 2500 points), pronounced peaks occurred at ~1580 cm−1 (G peak) and ~2700 cm−1 (2D peak), in addition to the D peak5152. The high quality of graphene was demonstrated by the average Raman spectrum of all points over the scanned area (ratio of D peak intensity ID to G peak intensity IG ~0.1) (Fig. 3a). The quality of graphene was further confirmed by Raman mapping of ID/IG (Fig. 3b). On most of the point ID/IG < 0.2; this low value suggests that the graphene layer has few surface defects. The number of layers and the uniformity of graphene over this area were also illustrated by Raman mapping of the 2D-to-G peak intensity ratio (I2D/IG) (Fig. 3c). Raman mapping of I2D/IG indicated that the multi-layer graphene consisted of mono-layer to few-layer portions (Fig. 3d), and that ~90% of the surface had I2D/IG ~0.7, which is the signature of three-layer graphene. In the average Raman spectrum, the 2D peak had full width at half-maximum of ~58 cm−1 and I2D/IG of ~0.62; these values are similar to those of three-layer graphene grown using CVD2528. The CTP-derived multi-layer graphene was further characterized by transmission electron microscopy (TEM). The graphene films were separated from SiO2 layer using sodium hydroxide solution (1M), then transferred to the TEM grids. TEM images at the folded edge of graphene films show that the multilayer graphene consisted of mono-layer to few-layer graphene with regular interlayer spacing (~0.34 nm) (Figure S3) in agreement with our Raman analysis data (Fig. 3e). Hexagonal crystalline structure of graphene was observed on a randomly-imaged graphene surface, (Fig. 3f) and electron diffraction on the graphene films revealed hexagonal patterns which are typically observed in multilayer graphene films (Fig. 3f, inset)2645. The measured sheet resistance of graphene grown on dielectric substrate was ~1 kΩ/sq and the minimum value was 906 Ω/sq.


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)

(a) Average Raman spectrum (2500 points) of coal tar pitch-derived graphene grown under Ni layer. (b) Raman mapping (100 × 100 μm) of D-to-G band peak intensity ratio (ID/IG) in coal tar pitch-derived graphene grown on Ni layer. Scale bar: 20 μm. (c) Raman mapping of 2D-to-G band peak intensity ratio (I2D/IG) in coal tar pitch-derived graphene grown on Ni layer. Scale bar: 20 μm. (d) Raman spectra of mono-layer to few-layer graphene formed on the SiO2/Si substrates that exists in the mapping area. (between Ni layer and SiO2/Si substrate). Lines have been shifted vertically for clarity. (e) TEM images of graphene films at the folded edge (f) TEM image of graphene surface. Inset: hexagonal electron diffraction pattern of graphene films.
© Copyright Policy - open-access
Related In: Results  -  Collection

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f3: (a) Average Raman spectrum (2500 points) of coal tar pitch-derived graphene grown under Ni layer. (b) Raman mapping (100 × 100 μm) of D-to-G band peak intensity ratio (ID/IG) in coal tar pitch-derived graphene grown on Ni layer. Scale bar: 20 μm. (c) Raman mapping of 2D-to-G band peak intensity ratio (I2D/IG) in coal tar pitch-derived graphene grown on Ni layer. Scale bar: 20 μm. (d) Raman spectra of mono-layer to few-layer graphene formed on the SiO2/Si substrates that exists in the mapping area. (between Ni layer and SiO2/Si substrate). Lines have been shifted vertically for clarity. (e) TEM images of graphene films at the folded edge (f) TEM image of graphene surface. Inset: hexagonal electron diffraction pattern of graphene films.
Mentions: CTP-derived graphene films grown on the SiO2/Si substrates at 1100 °C for 4 min were prepared for use in further characterization. This annealing condition was chosen based on the results of preliminary trials. In the Raman scanning over a large area (100 × 100 μm, 2500 points), pronounced peaks occurred at ~1580 cm−1 (G peak) and ~2700 cm−1 (2D peak), in addition to the D peak5152. The high quality of graphene was demonstrated by the average Raman spectrum of all points over the scanned area (ratio of D peak intensity ID to G peak intensity IG ~0.1) (Fig. 3a). The quality of graphene was further confirmed by Raman mapping of ID/IG (Fig. 3b). On most of the point ID/IG < 0.2; this low value suggests that the graphene layer has few surface defects. The number of layers and the uniformity of graphene over this area were also illustrated by Raman mapping of the 2D-to-G peak intensity ratio (I2D/IG) (Fig. 3c). Raman mapping of I2D/IG indicated that the multi-layer graphene consisted of mono-layer to few-layer portions (Fig. 3d), and that ~90% of the surface had I2D/IG ~0.7, which is the signature of three-layer graphene. In the average Raman spectrum, the 2D peak had full width at half-maximum of ~58 cm−1 and I2D/IG of ~0.62; these values are similar to those of three-layer graphene grown using CVD2528. The CTP-derived multi-layer graphene was further characterized by transmission electron microscopy (TEM). The graphene films were separated from SiO2 layer using sodium hydroxide solution (1M), then transferred to the TEM grids. TEM images at the folded edge of graphene films show that the multilayer graphene consisted of mono-layer to few-layer graphene with regular interlayer spacing (~0.34 nm) (Figure S3) in agreement with our Raman analysis data (Fig. 3e). Hexagonal crystalline structure of graphene was observed on a randomly-imaged graphene surface, (Fig. 3f) and electron diffraction on the graphene films revealed hexagonal patterns which are typically observed in multilayer graphene films (Fig. 3f, inset)2645. The measured sheet resistance of graphene grown on dielectric substrate was ~1 kΩ/sq and the minimum value was 906 Ω/sq.

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.