Graphite oxide (GO) formerly called graphitic oxide or graphitic acid, is a compound of carbon, oxygen, and hydrogen in variable ratios, obtained by treating graphite with strong oxidizers and acids for resolving of extra metals. The maximally oxidized bulk product is a yellow solid with C:O ratio between 2.1 and 2.9, that retains the layer structure of graphite but with a much larger and irregular spacing. Structure proposed in 1998 with functional groups. A: Epoxy bridges, B: Hydroxyl groups, C: Pairwise carboxyl groups. The bulk material spontaneously disperses in basic solutions or can be dispersed by sonication in polar solvents to yield monomolecular sheets, known as graphene oxide by analogy to graphene, the single-layer form of graphite. Graphene oxide sheets have been used to prepare strong paper-like materials, membranes, thin films, and composite materials. Initially, graphene oxide attracted substantial interest as a possible intermediate for the manufacture of graphene. The graphene obtained by reduction of graphene oxide still has many chemical and structural defects which is a problem for some applications but an advantage for some others .Graphite oxide was first prepared by Oxford chemist Benjamin C. Brodie in 1859, by treating graphite with a mixture of potassium chlorate and fuming nitric acid.He reported synthesis of "paper-like foils" with 0.05 mm thickness. In 1957 Hummers and Offeman developed a safer, quicker, and more efficient process called Hummers' method, using a mixture of sulfuric acid H2SO4, sodium nitrate NaNO3, and potassium permanganate KMnO4, which is still widely used, often with some modifications. Largest monolayer GO with highly intact carbon framework and minimal residual impurity concentrations can be synthesized in inert containers using highly pure reactants and solvents. Graphite oxides demonstrate considerable variation of properties depending on the degree of oxidation and the synthesis method. For example, the temperature point of explosive exfoliation is generally higher for graphite oxide prepared by the Brodie method compared to Hummers graphite oxide, the difference is up to 100 degrees with the same heating rates.Hydration and solvation properties of Brodie and Hummers graphite oxides are also remarkably different.Recently a mixture of H2SO4 and KMnO4 has been used to cut open carbon nanotubes lengthwise, resulting in microscopic flat ribbons of graphene, a few atoms wide, with the edges "capped" by oxygen atoms (=O) or hydroxyl groups (-OH). Graphite (graphene) oxide has also been prepared by using a "bottom-up" synthesis method (Tang-Lau method) in which the sole source is glucose, the process is safer, simpler, and more environmentally friendly compared to traditionally "top-down" method, in which strong oxidizers are involved. Another important advantage of the Tang-Lau method is the control of thickness, ranging from monolayer to multilayers, by adjusting growth parameters.

1. Introduction
Graphene and graphene oxide
Presented by Rajkamal Arya
(UPES DEHRADUN)

2. Graphene
It is a 2D crystal of carbon atoms, arranged in a honeycomb lattice & Each
carbon atom is sp2 hybridized and it is bound to its three neighbors.
● Coordination no. is 3
● It is the strongest, thinnest material known to exist.
● By stacking of graphene layers on top of each other, the well known 3-D
graphite crystal is formed. It is a basic building block for graphitic materials of
all other dimensionalities.
● It is a single graphite layer.

3. Chemical Properties:-
● Graphene is chemically the most reactive form of carbon.
● Only form of carbon (and generally all solid materials) in which each single
atom is in exposure for chemical reaction from two sides (due to the 2D
structure).
● Carbon atoms at the edge of graphene sheets have special chemical
reactivity.
● graphene burns at very low temperature (e.g.350°C).
● Graphene has the highest ratio of edgy carbons (in comparison with similar
materials such as carbon nanotubes).

4. Electronic properties:-
● It is a zero-overlap semimetal (with both holes and electrons as charge
carriers) with very high electrical conductivity.
● Electrons are able to flow through graphene more easily than through even
copper.
● The electrons travel through the graphene sheet as if they carry no mass, as
fast as just one hundredth that of the speed of light.
● High charge carrier mobility.

5. Mechanical properties:-
● To calculate the strength of graphene, scientists used a technique called
Atomic Force Microscopy.
● It was found that graphene is harder than diamond and about 300 times
harder than steel.
● The tensile strength of graphene exceeds 1 TPa. It is stretchable up to 20%
of its initial length.
● Due to this ,applications into making a new generation of super strong
composite materials and along combined with its optical properties, making
flexible displays.

6. Graphene oxide
● It is a monomolecular sheets of graphite oxide and it is a compound of carbon,
oxygen, and hydrogen in variable ratios, obtained by treating graphite with
strong oxidizers.
● Graphene oxide was first prepared by Oxford chemist Benjamin C. Brodie in
1859, by treating graphite with a mixture of potassium chlorate and fuming
nitric acid.
● In 1957 Hummers and Offeman developed a safer, quicker, and more efficient
process called The Hummers' Method, using a mixture of sulfuric acid
(H2SO4) and potassium permanganate (KMnO4) which is still used.

7. ● GO has been known as a graphite exfoliation yield through the reaction of
graphite flakes with strong oxidizing agent such as potassium permanganate
(KMnO4) in Conc. sulphuric acid .
● Several oxygenated functional group was decorated in atomic sheet of graphite
on its basal plane and its edges known as GO.
● Resulting in a hybrid structure comprising a composite of sp2 and sp3
hybridized carbon atoms.
● The sp2/sp3 ratios of the carbon atoms can be altered by tuning the degree of
oxidation and in turn, it will affect the properties of GO.

8. ● GO is often described as an electrical insulator, due to the disruption of
its sp2 bonding networks.
● In order to recover the honeycomb lattice, and with it the electrical
conductivity, the reduction of the graphene oxide has to be achieved.
● The reduced graphene oxide obtained is more difficult to disperse.
● Functionalization of GO can fundamentally change graphene oxide’s
properties. There are many ways in which graphene oxide can be
functionalized, depending on the desired application.

9. Effect of Oxydizing Agent On Synthesis Of GO:-
● Generally GO film was an electrical insulator,but when we increase the Conc.
of Oxydizing Agent (Kmno4) oxidation level of GO increases .
● Due to this Current of GO film increases and resistivity decreases.
● This suggests that an adequate amount of oxidizing agent is required for
graphite exfoliation.
● Exfoliation of graphite depends upon oxygen level of GO.

10. Characterization technique:-
● X-RAY Diffraction Patterns:-
● It is a non destructive technique.which is use to measure the interplaner
spacing b/w layers or rows of atoms .
● find the crystal structure of a unknown materials.
● To determine the structural properties
● The most important uses of XRD technique is to find phase identification
(1) Obtain XRD Patterns
(2) Measure d spacing
(3) Obtain integrated intensities
(4) Compare data with JCPDS file
(5) Plot the graph at origin

12. Applications:-
● Energy storage device - lithium-ion battery, Supercapictor
● Water treatment
● Gas sensing
● Membrens
● Treatment in cancer
● Biology
● Solar cell