A decade of graphene research

I. AN INTRODUCTION ABOUT GRAPHENE: a hexagonal structure consisting of sp2 hybridized carbon atoms  
Promising potential applications: longer-lasting batteries, more efficient solar cells, corrosion prevention, circuit boards, display panels,  and  medicinal  technologies  such  as  the  point-of-care detection of diseases

Graphene (top) and related structures: fullerene (bottom left); carbon nanotubes (bottom centre); and graphite (bottom right)

The current methods of large-scale graphene synthesis include many variations of the so-called ‘Hummers’ method, devised by William Hummers in the late 1950s 

The method utilizes powerful oxidizing agents and strong acids to strip apart the graphene layers from a source of graphite – usually a high grade graphite powder available from any good chemical supplier. However, as this method creates graphene oxide, it is necessary to reduce the graphene oxide further to create graphene, termed reduced graphene oxide, which depending on the success of the reduction process can yield near fully reduced graphene oxide (viz. graphene, usually termed rGO) or partially reduced graphene oxide

The best example to date of a chemically reduced graphene was presented in 2008 by Tung et al., who cleverly exploited the powerful reducing ability of hydrazine by immersing graphene oxide paper in pure hydrazine. Reportedly,  after  a few  hours  the  paper  disappears  to  leave  a  suspension  of  hydrazine with  graphene  platelets  dispersed  within.  The  graphene/hydrazine suspension  can  be  spin-coated  upon  a  substrate  such  as  silica  for characterization

The implications of such a highly permitting electron transport material are potentially profound in applications such as field effect transistors (FETs), which, even as of 2010, could operate at frequencies as high as 100 GHz

• a  high  thermal  conductivity  of  5000  W  m^-1/K 
• a high thermal conductivity of 5000 W m^-1/K 
• a high Young’s modulus of ~ 1 TPa
• extraordinarily large specific surface area of 2630 m²/g 

II. GRAPHENE APPLICATION

1. High-speed electronics
high conductivity => high-speed electronics

Graphene is a zero band gap material and hence has yet to make its commercial debut in this manner

One  particular  problem  with  graphene  based  transistors  originates  from  defects  emerging  upon  the  graphene  sheet during  the  fabrication  process  of  the  device.  That  said,  a  literature report  from  2010  emerged  which  utilized  a  self-aligning  Co₂Si–Al₂O₃ nanowire  as  a  gate  in  the  graphene  transistor  which  according  to  their  work  prevented  device  degradation  and  exhibited operational  frequencies  of  100–300  GHz

2. Data storage

Researchers investigating the storage properties of graphene oxides have shown that indium tin oxide electrodes modified with polymers and graphene oxide exhibit the write-read-erase-read-rewrite cycle for a non-volatile memory device

Current/voltage curves typical of the indium tin oxide electrode modified with polymers and graphene oxide. The curves 1–5 represent the relevant stage in the write-read-erase-read-rewrite cycle

3. Smart Windows/OLED displays

4. Supercapacitors
5. Solar cells
6. Electrochemical sensing