The present invention relates to a method for synthesizing graphene/sulfur composite, involving the steps of mixing graphene oxide (GO) with a hydrogen sulfide (H.sub.2S)-releasing agent in a sealed vessel, causing the H.sub.2S-releasing agent to release hydrogen sulfide, and then allowing the hydrogen sulfide to react with the graphene oxide at an elevated temperature and pressure to form said graphene/sulfur composite.

Methods and apparatuses to produce graphene and nanoparticle catalysts supported on graphene without the use of reducing agents, and with the concomitant production of heat, are provided. The methods and apparatuses employ radiant energy to reduce (deoxygenate) graphite oxide (GO) to graphene, or to reduce a mixture of GO plus one or more metals to produce nanoparticle catalysts supported on graphene. Methods and systems to generate and utilize heat that is produced by irradiating GO, graphene and their metal and semiconductor nanocomposites with visible, infrared and/or ultraviolet radiation, e.g. using sunlight, lasers, etc. are also provided.

A process for the preparation of graphene includes the steps of a) providing flash thermal treatment of a graphite oxide at a temperature up to 700° C. sufficient to produce exfoliation and under inert atmosphere and b) cooling the material obtained in the previous step below 90° C. The method further includes the step of c) heating the material resulting from the previous step under inert atmosphere at a temperature which is higher than the temperature of step a), wherein the heating rate is between 1 and 15° C./min. The graphenes obtained from the process exhibit excellent physico-chemical properties.

Existing methods of producing high quality graphene/graphite oxides are generally accomplished by exfoliating graphite into flakes and oxidizing the graphite flakes with strong oxidizers under extreme conditions and require careful purification. The oxidizers are typically strong acids used in high concentrations at elevated temperatures requiring complicated purification processes to yield oxidized graphene/sheets. The existing processes can cost up to $12,000/gram. This invention uses a mild oxidant combined with mechanical processing where the sole products are oxidized graphite/graphene and water without the need for further purification.

A method for enrichment of a mixture of graphene nanoplatelets (GNP) may include providing GNP into a column. The method may also include passing the GNP through an electrostatic field in a drift column to separate thinner GNP from thicker GNP to increase the content of the thinner GNP. The method may further include coupling a feeder to the drift column to accept the GNP and providing electrical charge to the GNP by the drift column with a charging module. The method may still further include generating the electrostatic field with an electrostatic field generator in the drift column to increase the content of GNP with smaller thickness.

A method for enrichment of a mixture of graphene nanoplatelets (GNP) may include providing GNP into a column. The method may also include passing the GNP through an electrostatic field in a drift column to separate thinner GNP from thicker GNP to increase the content of the thinner GNP. The method may further include coupling a feeder to the drift column to accept the GNP and providing electrical charge to the GNP by the drift column with a charging module. The method may still further include generating the electrostatic field with an electrostatic field generator in the drift column to increase the content of GNP with smaller thickness.

In one aspect of the invention, a dye sensitized solar cell has a counter-electrode including carbon-titania nanocomposite thin films made by forming a carbon-based ink; forming a titania (TiO.sub.2) solution; blade-coating a mechanical mixture of the carbon-based ink and the titania solution onto a substrate; and annealing the blade-coated substrate at a first temperature for a first period of time to obtain the carbon-based titania nanocomposite thin films. In certain embodiments, the carbon-based titania nanocomposite thin films may include solvent-exfoliated graphene titania (SEG-TiO.sub.2) nanocomposite thin films, or single walled carbon nanotube titania (SWCNT-TiO.sub.2) nanocomposite thin films.

In one aspect of the invention, a dye sensitized solar cell has a counter-electrode including carbon-titania nanocomposite thin films made by forming a carbon-based ink; forming a titania (TiO.sub.2) solution; blade-coating a mechanical mixture of the carbon-based ink and the titania solution onto a substrate; and annealing the blade-coated substrate at a first temperature for a first period of time to obtain the carbon-based titania nanocomposite thin films. In certain embodiments, the carbon-based titania nanocomposite thin films may include solvent-exfoliated graphene titania (SEG-TiO.sub.2) nanocomposite thin films, or single walled carbon nanotube titania (SWCNT-TiO.sub.2) nanocomposite thin films.

A process is disclosed comprising, providing a source of graphene, providing a particulate material, dispersing a mixture of the source of graphene and the particulate material in a first dispersion fluid to form a dispersion mixture, and providing a source of a base in the first dispersion fluid, thereby causing the source of graphene and particulate material in the dispersion mixture to interact forming a composite. The particulate material is preferably titanium dioxide comprising anatase and/or rutile which provides an effective photocatalytic composite. Also disclosed is apparatus to remove pollutants from fluids using the photocatalytically active material.

Described herein is an optical device that is arranged to emit electromagnetic radiation and a method of forming an optical device. In one embodiment, the optical device comprises an optical fibre that is arranged to transmit electromagnetic radiation between a source of electromagnetic radiation and an area of interest of a sample material. The optical device also comprises an optical element coupled to an end portion of the optical fibre. The optical element comprises a graphene lens that is arranged to focus the electromagnetic radiation transmitted by the optical fibre to a focal region within the area of interest of the sample material.