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Repeated growth and bubbling transfer of graphene with millimetre-size single-crystal grains using platinum.

Gao L, Ren W, Xu H, Jin L, Wang Z, Ma T, Ma LP, Zhang Z, Fu Q, Peng LM, Bao X, Cheng HM - Nat Commun (2012)

Bottom Line: The Pt substrates can be repeatedly used for graphene growth.The graphene shows high crystal quality with the reported lowest wrinkle height of 0.8 nm and a carrier mobility of greater than 7,100 cm(2) V(-1) s(-1) under ambient conditions.The repeatable growth of graphene with large single-crystal grains on Pt and its nondestructive transfer may enable various applications.

View Article: PubMed Central - PubMed

Affiliation: Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, China.

ABSTRACT
Large single-crystal graphene is highly desired and important for the applications of graphene in electronics, as grain boundaries between graphene grains markedly degrade its quality and properties. Here we report the growth of millimetre-sized hexagonal single-crystal graphene and graphene films joined from such grains on Pt by ambient-pressure chemical vapour deposition. We report a bubbling method to transfer these single graphene grains and graphene films to arbitrary substrate, which is nondestructive not only to graphene, but also to the Pt substrates. The Pt substrates can be repeatedly used for graphene growth. The graphene shows high crystal quality with the reported lowest wrinkle height of 0.8 nm and a carrier mobility of greater than 7,100 cm(2) V(-1) s(-1) under ambient conditions. The repeatable growth of graphene with large single-crystal grains on Pt and its nondestructive transfer may enable various applications.

No MeSH data available.


Illustration of the bubbling transfer process of graphene from a Pt substrate.(a) A Pt foil with grown graphene covered by a PMMA layer. (b) The PMMA/graphene/Pt in (a) was used as a cathode, and a Pt foil was used as an anode. (c) The PMMA/graphene was gradually separated from the Pt substrate driven by the H2 bubbles produced at the cathode after applying a constant current. (d) The completely separated PMMA/graphene layer and Pt foil after bubbling for tens of seconds. The PMMA/graphene layer is indicated by a red arrow in (c) and (d).
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f3: Illustration of the bubbling transfer process of graphene from a Pt substrate.(a) A Pt foil with grown graphene covered by a PMMA layer. (b) The PMMA/graphene/Pt in (a) was used as a cathode, and a Pt foil was used as an anode. (c) The PMMA/graphene was gradually separated from the Pt substrate driven by the H2 bubbles produced at the cathode after applying a constant current. (d) The completely separated PMMA/graphene layer and Pt foil after bubbling for tens of seconds. The PMMA/graphene layer is indicated by a red arrow in (c) and (d).

Mentions: The currently used etching-based transfer methods are not suitable for the transfer of graphene grown on Pt, as Pt is chemically inert and more expensive compared with Cu and Ni. Recently, an electrochemical delamination method was reported to transfer graphene grown on Cu25, but it was found that a thin layer of Cu, about 40 nm thick, was etched away during one transfer process. For graphene grown on Pt substrates, we have developed a bubbling transfer process, similar to the recently reported method25, to transfer the material based on a water electrolysis process32 (Fig. 3). After CVD growth, a Pt substrate with the graphene grown on it was first spin-coated with polymethyl methacrylate (PMMA) followed by curing. Then the PMMA/graphene/Pt was dipped into an NaOH aqueous solution and used as the cathode of an electrolysis cell with a constant current supply. It is worth noting that the graphene would be easily oxidized if the PMMA/graphene/Pt was used as the anode. At the negatively charged cathode, a water reduction reaction took place to produce H2. The reaction can be represented as follows: We observed that the PMMA/graphene layer was detached from the Pt substrate after tens of seconds as a result of the formation of a large number of H2 bubbles at the interface between the graphene and Pt substrate. This is much faster than the detachment of graphene by substrate etching, which usually takes tens of minutes to etch away substrates such as Cu and Ni. After cleaning with pure water, the floating PMMA/graphene layer was stamped at the target substrate. Finally, the PMMA was removed by acetone, and the graphene grains or films were transferred to the substrate successfully.


Repeated growth and bubbling transfer of graphene with millimetre-size single-crystal grains using platinum.

Gao L, Ren W, Xu H, Jin L, Wang Z, Ma T, Ma LP, Zhang Z, Fu Q, Peng LM, Bao X, Cheng HM - Nat Commun (2012)

Illustration of the bubbling transfer process of graphene from a Pt substrate.(a) A Pt foil with grown graphene covered by a PMMA layer. (b) The PMMA/graphene/Pt in (a) was used as a cathode, and a Pt foil was used as an anode. (c) The PMMA/graphene was gradually separated from the Pt substrate driven by the H2 bubbles produced at the cathode after applying a constant current. (d) The completely separated PMMA/graphene layer and Pt foil after bubbling for tens of seconds. The PMMA/graphene layer is indicated by a red arrow in (c) and (d).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3293422&req=5

f3: Illustration of the bubbling transfer process of graphene from a Pt substrate.(a) A Pt foil with grown graphene covered by a PMMA layer. (b) The PMMA/graphene/Pt in (a) was used as a cathode, and a Pt foil was used as an anode. (c) The PMMA/graphene was gradually separated from the Pt substrate driven by the H2 bubbles produced at the cathode after applying a constant current. (d) The completely separated PMMA/graphene layer and Pt foil after bubbling for tens of seconds. The PMMA/graphene layer is indicated by a red arrow in (c) and (d).
Mentions: The currently used etching-based transfer methods are not suitable for the transfer of graphene grown on Pt, as Pt is chemically inert and more expensive compared with Cu and Ni. Recently, an electrochemical delamination method was reported to transfer graphene grown on Cu25, but it was found that a thin layer of Cu, about 40 nm thick, was etched away during one transfer process. For graphene grown on Pt substrates, we have developed a bubbling transfer process, similar to the recently reported method25, to transfer the material based on a water electrolysis process32 (Fig. 3). After CVD growth, a Pt substrate with the graphene grown on it was first spin-coated with polymethyl methacrylate (PMMA) followed by curing. Then the PMMA/graphene/Pt was dipped into an NaOH aqueous solution and used as the cathode of an electrolysis cell with a constant current supply. It is worth noting that the graphene would be easily oxidized if the PMMA/graphene/Pt was used as the anode. At the negatively charged cathode, a water reduction reaction took place to produce H2. The reaction can be represented as follows: We observed that the PMMA/graphene layer was detached from the Pt substrate after tens of seconds as a result of the formation of a large number of H2 bubbles at the interface between the graphene and Pt substrate. This is much faster than the detachment of graphene by substrate etching, which usually takes tens of minutes to etch away substrates such as Cu and Ni. After cleaning with pure water, the floating PMMA/graphene layer was stamped at the target substrate. Finally, the PMMA was removed by acetone, and the graphene grains or films were transferred to the substrate successfully.

Bottom Line: The Pt substrates can be repeatedly used for graphene growth.The graphene shows high crystal quality with the reported lowest wrinkle height of 0.8 nm and a carrier mobility of greater than 7,100 cm(2) V(-1) s(-1) under ambient conditions.The repeatable growth of graphene with large single-crystal grains on Pt and its nondestructive transfer may enable various applications.

View Article: PubMed Central - PubMed

Affiliation: Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, China.

ABSTRACT
Large single-crystal graphene is highly desired and important for the applications of graphene in electronics, as grain boundaries between graphene grains markedly degrade its quality and properties. Here we report the growth of millimetre-sized hexagonal single-crystal graphene and graphene films joined from such grains on Pt by ambient-pressure chemical vapour deposition. We report a bubbling method to transfer these single graphene grains and graphene films to arbitrary substrate, which is nondestructive not only to graphene, but also to the Pt substrates. The Pt substrates can be repeatedly used for graphene growth. The graphene shows high crystal quality with the reported lowest wrinkle height of 0.8 nm and a carrier mobility of greater than 7,100 cm(2) V(-1) s(-1) under ambient conditions. The repeatable growth of graphene with large single-crystal grains on Pt and its nondestructive transfer may enable various applications.

No MeSH data available.