Recent Two Methods to Make Graphene for Chemists

As my last atom said, grahene has so many fantastic properties that investigators in both physics and chemisty are interesting in the field.
However, making graphene is a big problem. Generally, the most common method is to exfoliate graphene pieces from a gaphite crystal with mechanical force. It is difficult to repeat with this method and its limitation kept most of chemists from wider usage.

Just at the end of last month, we have the first hope. Prof. Hongjie Dai in Stanford gave us a new method without mechanical exfoliation (Science Vol. 319, 1229 (2008)). Prof. Dai have worked with the non-convalent interactin between several conjugated molecules and carbon nanotube. Since the similarity between carbon nanotube and graphene, it is easy to understand Dai's idea. In Dai's work, gaphite was treated in 1000 degree with Ar gas protecting including 3% hydrogen. So the graphene was made with the high temperature treatement. But it was a mixture. So the next step was to separate graphene from others. Dai used a polymer called PmPV which is very common in the non-convalent modification in carbon nanotube. PmPV is a conjugated molecule which has a strong interaction between it and graphene while the complex can be dissolved in CH2Cl2. The gaphite and other things stayed in the sediments and the graphene in solvent. That is the prinple of Dai's method. In the article, there are other characteristics o f AFM image and transistor properties. It is a great job because the method is so familiar for persons in carbon nanotube that it will attract their interests.
This week there is another new progress published in web of JACS (DOI: 10.1021/ja710234t). It is a total synthesis of grpahene nanoribbons with the several basic reactions applied in the organic molecular electronics. James Tour has used these reaction to develop a series of molecular wire and other devices so called OPE. Now they are used in the investigations on graphene by some guys in Max-Planck institue of Polymer Research. As we know the department is good at making flat polymer. Since all reactions are common in organic chemistry, it is meaningful for organic chemists. If someone will, you can find the details in web of JACS. (It is strange that I can't upload the picture.) It gives us a complete new method to synthesize but not find the graphene. It is a pity that they can only synthesize armchair-edge graphene with the method until now. The synthsis of zigzag-edge graphene will be more meaningful for its half-metallic properties.
I believe that the new gold rush of graphene will come in the near future if these method are used widely. After fullerene and carbon nanotube, graphene will be another star molecule in nanoscience.

New progress of graphene

Here is a brief introduction from my seminar about the new progress of graphene and its derivates:
Recently, great interests have been ignited on transport in novel 2D nanostructures for the remarkable electronic properties. 2D nanostructures can fit the approximation of 2D electron gas and different kinds of theory based on the approximation in condensed matter physics very well. As the most rising star, Graphene, a single layer of graphite is different from the conventional 2D nanostructure due to the linear energy dispersion relation near the charge neutrality (Dirac) point in the electronic band structure (the touch between CB and VB) which refers the extra-high mobilities. It is even reported the massless electrons in the transport through graphene. From the present researches, it is also responsible for quantum Hall effect and other extraordinary properties. As a result, graphene is applied on functional devices such as logic circuits, transistors, memories and sensors.

The orientation of graphene sheet between electrodes is one of the elements in the investigations on charge transport which is the same as carbon nanotubes. As an alternative, graphene nanoribbon can realize the major function of graphene sheet. The description of electrons in it is revised from 2D electron gas as well while it has the symmetry of 1D systems, so it has the unique properties such as the half-metallic phenomenon. However, the properties of graphene ribbons depend on the orientation extremely which are proved both theoretically and experimentally. Therefore, it is important to investigate the effect of orientation in graphene and its derivates for the further application in nanoelectronics.