We investigate Raman spectra of graphite oxide and functionalized graphene sheets with epoxy and hydroxyl groups and Stone-Wales and 5-8-5 defects by first-principles calculations to interpret our experimental results. Only the alternating pattern of single-double carbon bonds within the sp2 carbon ribbons provides a satisfactory explanation for the experimentally observed blue shift of the G b...

The intercalation of lithium into graphite was discovered in the 1950's.' After that, many studies focused on the staged phases ' that are formed during lithium intercalation in graphite and in graphitic carbon types. Safran concluded that the staging phenomenon is the result of the competition between interlayer repulsive and in-plane attractive interactions between the intercalated lithium. S...

Graphite oxide was synthesized from natural flake graphite by the modified Hummers method. In brief, 200 mg of Graphite particles were immersed in Concentrated sulfuric acid (46 ml) and KMnO4 (6 g) was added slowly in small quantities in which temperature was maintained between the 0 and 5 c using an ice bath, after the complete oxidation of KMnO4, the mixture was heated to 37 c and kept at thi...

Optical microscope images of graphite oxide (GO) reveal the occurrence of fault lines resulting from the oxidative processes. The fault lines and cracks of GO are also responsible for their much smaller size compared with the starting graphite materials. We propose an unzipping mechanism to explain the formation of cracks on GO and cutting of carbon nanotubes in an oxidizing acid. GO unzipping ...

Herein we report a one-step, low cost, photocatalytic method for the synthesis of graphene oxide (GO) from commercial graphite using grey TiO2 as photocatalyst. GO formation is achieved by UV-illumination slurry well-dispersed and graphite. Light-induced valence-band holes then lead to an oxidation exfoliation graphite, resulting in visible-light-active GO. An optimal level can be established c...

Reduced graphene oxide(rGO)–silver(Ag) nanocomposites have been prepared by using solution based facile one-pot synthesis process. The reaction process involves high-temperature liquid-phase exfoliation of graphite oxide and silver acetate in presence of N-N’dimethylformamide (DMF) solvent, resulting in simultaneous formation of rGO as well as Ag nanoparticles. Different nanocomposites have bee...

We present a general study on a high performance supercapacitor based on intercalated reduced graphene oxide with carbon black nanoparticles. Graphene oxide sheets were synthesized by oxidation and exfoliation of natural graphite and were reduced using hydroiodic acid in the presence of carbon black nanoparticles. Graphene paper was fabricated by one-step procedure via simultaneous reducing and...

Graphite oxide sheet, now called graphene oxide (GO), is the product of chemical exfoliation of graphite and has been known for more than a century. GO has been largely viewed as hydrophilic, presumably due to its excellent colloidal stability in water. Here we report that GO is an amphiphile with hydrophilic edges and a more hydrophobic basal plane. GO can act like a surfactant, as measured by...

Chemical exfoliation of graphite under strong oxidizing conditions yields graphene oxide nanosheets with oxy functional groups on the carbon basal plane. The importance of ozone in the chemical oxidation mechanism of graphite by the widely-used Hummers' method has been largely overlooked. Herein we demonstrate that the ozonolysis of graphite leads to the formation of secondary epoxy and peroxym...