The present disclosure provides supercapacitors that may avoid the shortcomings of current energy storage technology. Provided herein are electrochemical systems, comprising three dimensional porous reduced graphene oxide film electrodes. Prototype supercapacitors disclosed herein may exhibit improved performance compared to commercial supercapacitors. Additionally, the present disclosure provides a simple, yet versatile technique for the fabrication of supercapacitors through the direct preparation of three dimensional porous reduced graphene oxide films by filtration and freeze casting.

There are provided a graphene having an oxygen atom content in a predetermined range or less and a carbon/oxygen weight ratio in a specific range to show excellent electrical and thermal conductivity properties, and a barrier property, and a method and an apparatus for preparing the graphene having excellent electrical and thermal conductivity properties and a barrier property by using a subcritical-state fluid or a supercritical-state fluid. According to the method and the apparatus for preparing the graphene, impurities such as graphene oxide, and the like, may be effectively removed, such that uniformity of the graphene to be prepared may be increased, and therefore, the graphene which is highly applicable as materials throughout the industry may be mass-produced.

A method of producing dispersed of high quality graphene/graphite oxides in a powder matrix to then be reacted to form a composite. Where the powders have similar hydrophobicity and the graphene/graphite oxides has minimal surface oxidation or minimal epoxy group and where the powders are sonically mixed.

The object of the present invention is to provide linked stacks of reduced graphene, in which excellent electrical property on the surface of graphene may be utilized, a method for producing the same, powder comprising the same, and film comprising the same. The object may be solved by using linked stacks of partly reduced graphene 11 comprising two or more stacks of partly reduced graphene 21 to 24 linked together, in which the stack of partly reduced graphene 21 has two or more sheets of partly reduced graphene 31 and a nanosubstance 32 held between the sheets of partly reduced graphene 31, the partly reduced graphene 31 has no carbonyl groups and has carboxyl groups 31a and hydroxyl groups 31b, and different stacks of partly reduced graphene 21 to 24 are linked to each other by an ester bond 34.

A method for obtaining graphene oxide is provided comprising the steps of a) adding an acid and a salt to graphite for obtaining a graphite oxide, and b) exfoliating the graphite oxide by mixing it, wherein the steps a) and b) are carried out simultaneously in a high shear mixer.

A method is provided for fabricating a graphene-doped, carbohydrate-derived hard carbon (G-HC) composite material for alkali metal-ion batteries. The method provides graphene oxide (GO) dispersed in an aqueous solution. A carbohydrate is dissolved into the aqueous solution and subsequently the water is removed to create a precipitate. In one aspect, the carbohydrate is sucrose. The precipitate is dehydrated and exposed to a thermal treatment of less than 1200 degrees C. to carbonize the carbohydrate. The result is the formation of a graphene-doped, carbohydrate-derived hard carbon (G-HC) composite. Typically, the G-HC composite is made up of graphene in the range of 0.1 and 20% by weight (wt %), and HC in the range of 80 to 99.9 wt %. The G-HC composite has a specific surface area of less than 10 square meters per gram (m.sup.2/g). A G-HC composite suitable for use in alkali metal-ion batteries electrodes is also provided.

A graphene quantum dots synthesis method includes fixing a graphene aqueous solution or a graphene oxide aqueous solution on a spin coater to spin the graphene aqueous solution or the graphene oxide aqueous solution, and irradiating a pulsed laser to focus on a graphene aqueous solution or a graphene oxide aqueous solution to generate exfoliation. After a processing period, quantum dots are generated in the graphene aqueous solution or the graphene oxide aqueous solution. Since graphene aqueous solution or graphene oxide aqueous solution does not contain organic chemistry pharmacy, the quantum dots synthesized by the method of the present invention can be produced without pollution. Furthermore, the purpose of simple process, low cost, and time-saved of synthesis can be achieved.

The present invention relates to a partially oxidized graphene and a method for preparing the same. Since the partially oxidized graphene is prepared by subjecting the partially oxidized graphite to a high pressure homogenization, the exfoliation efficiency is excellent, the inherent characteristics of graphene are maintained even without using a reduction step after exfoliation, and the dispersibility thereof in organic solvents is excellent, and thus the invention can be applied to various fields.

Embodiments of the present invention encompass methods of forming graphene from graphene oxide and/or graphite oxide using tomato juice.

Embodiments of the present invention encompass methods of forming graphene from graphene oxide and/or graphite oxide using tomato juice.