GRAPHENE MANUFACTURE

Abstract

A method of manufacturing a graphene sheet comprising the steps of: providing a container containing liquid and a volume above the liquid; supplying carbon atoms to the volume; and allowing carbon atoms to settle on the surface of the liquid and to coalesce to form the graphene sheet.

Claims

1. A method of manufacturing a graphene sheet comprising the steps of: providing a container containing a liquid and a volume above the liquid; supplying carbon atoms to the volume; and allowing carbon atoms to settle on the surface of the liquid and to coalesce to form the graphene sheet.

2. The method according to claim 1 in which the carbon atoms coalesce to form a plurality of graphene fragments on the surface of the liquid, and the graphene fragments are allowed to coalesce to form the graphene sheet.

3. The method according to claim 1 in which the step of supplying carbon atoms comprises creating the carbon atoms by photolysis, electrical discharge, decomposition, cracking or fracking.

4. The method according to claim 1 in which the step of supplying the carbon atoms comprises creating the carbon atoms in the container.

5. The method according to claim 1 in which the container comprises at least one source of localized carbon atoms, which is moved within the container to control the distribution of carbon atoms on the surface of the liquid.

6. The method according to claim 1 wherein the carbon atoms are created using a carbon containing precursor gas, such as a hydrocarbon gas.

7. The method according to claim 1 wherein the carbon atoms are created using particulate graphite as a precursor.

8. The method according to claim 1 wherein the settling is effected by one or more of gravity, condensation, interatomic forces, the presence of a gaseous atmosphere in the volume above the liquid, and control of the conditions in the container such as temperature and pressure.

9. The method according to claim 1 wherein the liquid is agitated, to allow the carbon atoms and/or graphene fragments to coalesce.

10. The method according to claim 9 in which the liquid is agitated mechanically or by ultrasound.

11. The method according to claim 1 in which the volume above the liquid contains a gaseous atmosphere at a desired pressure.

12. The method according to claim 1 further comprising the step of removing the graphene sheet from the container.

13. The method according to claim 12 the graphene sheet is removed firstly by draining the liquid from the container and secondly collecting the graphene sheet.

14. The method according to claim 13 wherein a liquid-porous substrate is located within the liquid and acts as a support for the graphene sheet once the liquid has drained through the liquid-porous substrate.

15. The method according to claim 14 wherein the liquid-porous substrate is removable from the container.

16. The method according to claim 12 in which the graphene sheet is removed from the substrate of the liquid by a device.

17. The method according to claim 16 wherein the graphene sheet is removed by a roller device.

18. Apparatus for manufacturing a graphene sheet comprising: a container containing a liquid and a volume above the liquid and; a carbon atom source for supplying carbon atoms to the volume so that the carbon atoms can settle on the surface of the liquid; wherein the apparatus is configured to allow the carbon atoms to coalesce to form the graphene sheet.

19. Apparatus according to claim 18 further comprising an agitator for agitating the liquid.

20. A graphene sheet manufactured by a method according to claim 1.

21. (canceled)

Description

[0030] The present invention will now be described with reference to the accompanying drawings in which:

[0031] FIG. 1(a) and (b) show a first embodiment for forming a graphene sheet;

[0032] FIG. 2(a) and (b) show a method of separating a graphene sheet from a liquid;

[0033] FIG. 3(a) and (b) show an alternative method of separating graphene from a liquid; and

[0034] FIG. 4(a), (b) and (c) show a second embodiment for forming a graphene sheet.

[0035] FIG. 1(a) shows a container 10 containing a liquid 12. The container 10 may be heated and/or pressurised to ensure the liquid is at the optimum temperature and pressure to allow the formation of graphene sheets. A source of carbon atoms 14 is created in the volume of the container 10 above the liquid 12. The carbon atoms may be created from a precursor which is introduced through a port 16. Carbon atoms from the source 14 settle on the surface of the liquid 12 to form liquid-carbon bonds. Subsequently, carbon-carbon bonding results in the deposition of graphene fragments 18. Carbon-carbon bonding can occur through random motion of the carbon atoms on the liquid surface and/or deliberate agitation of the liquid. Any unwanted materials 20 may sink below the surface 22 of the liquid so they are not included as part of the graphene sheet. Alternatively, the liquid may dissolve by-product species. FIG. 1(b) shows the container 10 having an agitator 24 which agitates the liquid 12 to encourage graphene formation. The agitator may be an ultrasound device or a mechanical device which causes swirling of the liquid. The graphene assembles into sheets 26. The surface of the liquid acts to retain the two dimensional structure of the graphene sheet.

[0036] FIG. 2(a) shows a method of separating the graphene sheet 26 from the liquid 12. The container 10 has a drain port 28 through which the liquid 12 is drained.

[0037] The container has a liquid-porous substrate 30 located within it and which is located in the liquid 12. FIG. 2(b) shows the liquid being drained through the drain port 28. As the liquid level within the container drops so does the graphene sheet 26 until it comes to rest on the liquid-porous substrate 30. The liquid-porous substrate 30 can then be removed from the container 10 and the graphene sheet 26 can be removed from the liquid-porous substrate 30 by any suitable method.

[0038] FIG. 3(a) shows an alternative method of removing a graphene sheet 26 from a container 10. A roller 32 is introduced into the container after the graphene sheet 26 has been formed. The roller 32 is then rotated about its central axis over the surface of the graphene sheet 26 so that the graphene sheet 26 is wrapped around the roller 32 as is shown in FIG. 3(b). The roller can then be removed from the container and the graphene sheet can be removed from the roller. The roller can be supported by any suitable means to allow rotation of the roller so that it can roll over the surface of the graphene sheet 26. If the size of the graphene sheet is such that the graphene layer would be wrapped around the roller more than once, then a weakly binding substrate could be used to avoid adjacent layers of graphene binding to each other.

[0039] FIG. 4 shows an alternative embodiment of manufacturing a graphene sheet using the container 10 containing liquid 12. In this embodiment, the container 10 comprises a translating source of atomic carbon which is configured to be translatable across the container 10 from a position on the left hand side as shown in FIG. 4(a) to a position on the right hand side as shown in FIG. 4(b). The source of the atomic carbon 42 produces carbon atoms 44 which settle onto the surface of the liquid 12. The settled carbon atoms as shown in

[0040] FIG. 4(a) are denoted by the numeral 40. The flow of the carbon atoms 44 from the source of the atomic carbon 42 may be to some extent directional. The movement of the source of atomic carbon 42 across the container 10 allows the production of a relatively even distribution of carbon atoms 40 on the surface of the liquid 12. The carbon atoms 40 coalesce to form a plurality of graphene fragments 18. Suitable agitation of the liquid by the agitator 24 may enhance this process. The essentially planar nature of the surface of the liquid 12 encourages the formation and retention of a two dimensional structure. The graphene fragments 18 can be regarded as discrete floating islands. Continuing agitation by an agitator 24 results in the graphene fragments 18 moving and bonding with other graphene fragments 18 to eventually form a large graphene sheet 26 on the surface of the liquid 12. The graphene sheet 26 can then be separated from the liquid 12, for example using the techniques described in relation to FIGS. 2 and 3.

[0041] The formation of the graphene sheet may be monitored in-situ by a suitable technique. For example, reflected high-energy electron diffraction (RHEED) or an optical technique, such as reflectometry, ellipsometry, reflectance anisotropy or Raman scattering, might be used.

[0042] Variants, modifications, additions and omissions relating to the description above are possible within the ambit of the invention and will be readily apparent to the skilled addressee.