Chemically Derived Graphene

2010

High Mobility, Printable, and Solution-Processed Graphene Electronics

 

Nano Lett., 2010, 10 (1), pp 92–98

 

Shuai Wang, Priscilla Kailian Ang, Ziqian Wang, Ai Ling Lena Tang, John T. L. Thong and Kian Ping Loh

 

 

The ability to print graphene sheets onto large scale, flexible substrates holds promise for large scale, transparent electronics on flexible substrates. Solution processable graphene sheets derived from graphite can form stable dispersions in solutions and are amenable to bulk scale processing and ink jet printing. However, the electrical conductivity and carrier mobilities of this material are usually reported to be orders of magnitude poorer than that of the mechanically cleaved counterpart due to its higher density of defects, which restricts its use in electronics. Here, we show that by optimizing several key factors in processing, we are able to fabricate high mobility graphene films derived from large sized graphene oxide sheets, which paves the way for all-carbon post-CMOS electronics. All-carbon source?drain channel electronics fabricated from such films exhibit significantly improved transport characteristics, with carrier mobilities of 365 cm2/(V·s) for hole and 281 cm2/(V·s) for electron, measured in air at room temperature. In particular, intrinsic mobility as high as 5000 cm2/(V·s) can be obtained from such solution-processed graphene films when ionic screening is applied to nullify the Coulombic scattering by charged impurities.

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Microwave synthesis of large few-layer graphene sheets in aqueous solution of ammonia

 

Nano Research, 2010

 

Izabela Janowska , Kambiz Chizari, Ovidiu Ersen, Spyridon Zafeiratos, Driss Soubane, Victor Da Costa, Virginie Speisser, Christine Boeglin, Matthieu Houllé, Dominique Bégin, Dominique Plee, Marc-Jacques Ledoux and Cuong Pham-Huu

 

 

Few-layer graphene (FLG) sheets with sizes exceeding several micrometers have been synthesized by exfoliation of expanded graphite in aqueous solution of ammonia under microwave irradiation, with an overall yield approaching 8 wt.%. Transmission electron microscopy (in bright-field and dark-field modes) together with electron diffraction patterns and atomic force microscopy confirmed that this graphene material consisted mostly of mono-, bi- or few-layer graphene (less than ten layers). The high degree of surface reduction was confirmed by X-ray photoelectron and infrared spectroscopies. In addition, the high stability of the FLG in the liquid medium facilitates the deposition of the graphene material onto several substrates via low-cost solution-phase processing techniques, opening the way to subsequent applications of the material.

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Nitrogen-Doped Graphene as Efficient Metal-Free Electrocatalyst for Oxygen Reduction in Fuel Cells

 

ACS Nano, Article ASAP, 2010

 

Liangti Qu, Yong Liu, Jong-Beom Baek and Liming Dai

 

Nitrogen-doped graphene (N-graphene) was synthesized by chemical vapor deposition of methane in the presence of ammonia. The resultant N-graphene was demonstrated to act as a metal-free electrode with a much better electrocatalytic activity, long-term operation stability, and tolerance to crossover effect than platinum for oxygen reduction via a four-electron pathway in alkaline fuel cells. To the best of our knowledge, this is the first report on the use of graphene and its derivatives as metal-free catalysts for oxygen 3D printing webstore reduction. The important role of N-doping to oxygen reduction reaction (ORR) can be applied to various carbon materials for the development of other metal-free efficient ORR catalysts for fuel cell applications, even new catalytic materials for applications beyond fuel cells.

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High yield fabrication of chemically reduced graphene oxide field effect transistors by dielectrophoresis

 

Daeha Joung, A. Chunder, Lei Zhai, Saiful I. Khondake

 

Date: 2 Feb 2010

 

This paper provides a new route for large scale production  of graphene based nanoelectronic devices. High yield fabrication of field effect transistors (FET) using chemically reduced graphene oxide (RGO) sheets suspended in water assembled via dielectrophoresis has been demonstrated.

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