HK1229066A1

HK1229066A1 - Perforating two-dimensional materials using broad ion field

Info

Publication number: HK1229066A1
Application number: HK17102615.2A
Authority: HK
Inventors: P．V．贝得沃斯
Original assignee: 洛克希德马丁公司
Priority date: 2014-01-31
Filing date: 2015-01-30
Publication date: 2017-11-10

Description

Perforating two-dimensional materials using wide ion fields

Cross Reference to Related Applications

This application is based on priority of U.S. provisional patent application No. 61/934,530, filed 2014 1, 31, § 119 requirements 2014, which is incorporated herein by reference in its entirety.

Statement regarding rights to inventions made under federal research

Not applicable.

FIELD

The present disclosure relates generally to two-dimensional materials and, more particularly, to methods of perforating two-dimensional materials.

Background

Graphene represents a form of carbon in which the carbon atom is present in a single atom-thick thin layer or multiple thin layers of six-membered fused ringsThe layered sheets (e.g., about 20 or less) form an extended planar lattice. Graphene has gained widespread interest in many applications in its various forms, primarily due to its advantageous combination of high electrical and thermal conductivity values, good in-plane mechanical strength, and unique optical and electrical properties. In many respects, the properties of graphene are comparable to those of carbon nanotubes, since both nanomaterials are based on extended sp²-a hybrid carbon framework. Other two-dimensional materials having a thickness of a few nanometers or less and an extended planar lattice are also of interest in many applications. In one embodiment, the two-dimensional material has a thickness of 0.3 to 1.2 nm. In other embodiments, the two-dimensional material has a thickness of 0.3 to 3 nm.

Due to its extended planar structure, graphene provides some functions that are not shared with carbon nanotubes. Of particular interest to the industry are large area graphene films that can be used, for example, for special barrier layers, coatings, large area conductive elements (e.g., radio frequency radiators (RF radiators) or antennas), integrated circuits, transparent electrodes, solar cells, gas barriers, flexible electronics, and the like. Furthermore, current graphene films can be produced in large quantities more cheaply than carbon nanotubes.

Some of the expected applications for graphene and other two-dimensional materials are predicted based on the formation of a plurality of nanoscale pores in the planar structure of these nanomaterials. Methods of forming pores in graphene and other two-dimensional materials are referred to herein as "perforation" and such nanomaterials are referred to herein as "perforated". In graphene sheets, interstitial pores are formed by each six-membered carbon atom ring structure in the sheet layer, and the interstitial pores are less than one nanometer span. In particular, the interstitial pore size is considered to be about 0.3nm along its longest dimension (the center-to-center distance between carbon atoms is about 0.28nm, and the pore size is slightly smaller than this distance). Typically, perforating a thin layer having a two-dimensional network structure refers to forming holes in the network structure that are larger than the interstitial pores.

The perforation of graphene and other two-dimensional materials can change the electrical properties of the material and the resistance to fluid flow through the material. For example, the pore density of the perforated graphene may be used to tune the conductivity, and, in some cases, the band gap, of the nanomaterial. Filtration applications are another area of considerable interest in perforated graphene and other perforated two-dimensional materials. Due to the atomic thinness of graphene and other two-dimensional materials, it is possible to achieve high liquid flux rates during filtration, even if the pores present are only of a single nanometer size.

High performance, high selectivity filtration applications depend on the presence of a sufficient number of pores of the desired size in the filtration membrane. While many methods of perforating graphene and other two-dimensional materials are known, producing pores with a desired size range, narrow size distribution, and high pore density remains a challenge. In conventional perforation methods, at least some of these parameters are typically lacking.

Chemical techniques can be used to create pores in graphene and other two-dimensional materials. Exposure of graphene and other two-dimensional materials to ozone or atmospheric plasma (e.g., oxygen/argon or nitrogen/argon plasma) can achieve perforation, but these holes are often deficient in density and size distribution. In many cases, it is difficult to control pore nucleation and pore growth separately, and therefore these methods typically produce a broad distribution of pore sizes. Furthermore, many chemical perforation techniques produce pores that are extreme: 1) extreme holes of low hole density and small hole size, and 2) extreme holes of high hole density and large hole size. These extreme pores are particularly undesirable for filtration applications. The first extreme pore is detrimental to flux and the second extreme pore is detrimental to selective exclusion of impurities smaller than the pore size.

Physical techniques can also be used to remove material from a planar structure of a two-dimensional material to create pores. High thermal ion beams tend to create holes in graphene and other two-dimensional materials that are too small to allow effective filtering, primarily because graphene and other two-dimensional materials react quite poorly with ions at high thermal velocities. The high thermal energy range is defined as being between the thermal energy range and the low energy range. For example, the high thermal energy range includes an energy range between 1eV and 500 eV. Conversely, focused ion beams tend to form an excessively small number of holes. Focused ion beams are also extremely destructive to many substrates on which two-dimensional materials are placed due to their high energy flux. Due to their high energy requirements and small beam size, it is also impractical to use focused ion beams to perforate large-sized regions.

Perforated nanomaterials with pores ranging in size from about 0.3nm to about 10nm, high pore density and narrow pore size distribution are particularly difficult to prepare. Having pores in this size range is particularly effective for a variety of different filtration applications including, for example, reverse osmosis, molecular filtration, ultrafiltration, and nanofiltration processes. For example, pores having a size in the range of 0.3nm to 0.5nm may be used in certain gas separation processes. Pores ranging in size from 0.7nm to 1.2nm may be useful in certain desalination processes.

In view of the above, there is a great need in the art for scalable methods for perforating graphene and other two-dimensional materials to produce pores with high pore density, narrow size distribution, and small pore size. In particular, there is a great need in the art for a scalable process for producing pores having a size, pore density and size distribution suitable for different filtration applications. The present disclosure satisfies the needs described above and provides related advantages.

SUMMARY

In various embodiments, methods of perforating a two-dimensional material are described herein. In one aspect, exposing a composite material comprising a layer of a two-dimensional material and a layer of another material to an ion source creates a plurality of pores in the two-dimensional material, even when the energy and/or flux of the ions is relatively low. In one embodiment, the other material layer is not a sheet or thin layer of two-dimensional material.

In some embodiments, a method of perforating may comprise:(1) exposing a two-dimensional material to an ion source, wherein the two-dimensional material is in contact with at least one layer of material different from the two-dimensional material, and (2) interacting a plurality of ions from the ion source with the two-dimensional material and with the at least one layer of material. In one embodiment, the at least one layer is in continuous contact with the two-dimensional material when the two-dimensional material is exposed to the ion source. In one embodiment, the ions introduce a plurality of defects in the two-dimensional material, and interaction of the ions with the at least one layer facilitates expansion of the defects into the plurality of pores defined in the two-dimensional material. In some embodiments, the ion source provides the following ion energy ranges: from 0.75keV to 10keV, from 1keV to 5keV, from 2keV to 10keV, or from 5keV to 10 keV. In some embodiments, the ion source provides a range of ion doses from 1x10¹⁰Ion/cm²To 1x10¹⁷Ion/cm²From 1x10¹¹Ion/cm²To 1x10¹⁵Ion/cm²Or from 1x10¹³Ion/cm²To 1x10¹⁹Ion/cm²。

In one embodiment, the method comprises the steps of: exposing a composite multilayer material to ions generated by an ion source, the multilayer material comprising a first layer comprising a two-dimensional first material, and a second layer of a second material in contact with the first layer; and creating a plurality of apertures in the two-dimensional first material by interaction of a plurality of ions from the ion source, neutralizing ions from the ion source, or a combination thereof with the two-dimensional first material and the second material. In one embodiment, the ion source is a broad beam or flood source. In some embodiments, with respect to neutralizing ions, at least a portion of the ions originating from the ion source are neutralized when interacting with the multilayer material. For example, ions may be neutralized near the surface of a given layer or during collisions within a layer. In one embodiment, the first layer has a first side and a second side, wherein the first side faces the ion source. The first side of the first layer may be referred to as the "front side" of the first layer.

In one embodiment, the second layer is a front layer disposed on the first side of the first layer. During exposure of the multilayer material to the ion source, at least a portion of the ions and/or neutralizing ions interact with the material of the front layer, and a substantial amount of the ions and/or neutralizing ions pass through the front layer and subsequently react with the layer comprising the two-dimensional material. In one embodiment, the front layer is removed after perforation. When the second layer is a "back layer" disposed on the second side of the first layer, at least a portion of the ions and/or neutralizing ions interact with the two-dimensional material of the first layer, and a plurality of ions and/or neutralizing ions pass through the first layer and subsequently react with the back layer. The multilayer material may further include a third layer of a third material. In one embodiment, the third layer is disposed on the opposite side of the first layer relative to the second layer, such that the first layer comprising the two-dimensional material is in contact with both the front and back layers of the other material.

In one embodiment, the second material is selected such that the interaction of the ions and/or neutralizing ions with the second material facilitates the perforation process. In one embodiment, the interaction of the second material with the ions and/or neutralizing ions may form fragments. The type of debris formed depends at least in part on the second material. The fragments may be atomic, ionic or molecular fragments (e.g., a portion of a polymer chain).

When the layer of the second material is a front layer, the thickness of the layer is sufficiently thin to allow ions and/or neutralizing ions to penetrate into the layer comprising the two-dimensional material. In one embodiment, the layer of the second material has an average thickness of 1 to 10 nm. The front layer may be continuous or discontinuous. In some embodiments, the at least one layer may be, for example, deposited silicon, deposited polymer, condensed gas or condensed organic compound, or any combination thereof. In some embodiments, the polymer comprises the elements carbon and hydrogen, and optionally, further comprises one or more elements selected from the group consisting of: silicon, oxygen, nitrogen, fluorine, chlorine and bromine. In some embodiments, the polymer is polycarbonate, polyacrylate, polyethylene oxide, epoxy, silicone, Polytetrafluoroethylene (PTFE), or polyvinyl chloride (PVC). In one embodiment, the condensing gas is an inert gas, such as xenon. In embodiments, the condensed organic compound is a thiol, amine, or alcohol. In one embodiment, the organic compound comprises an alkyl group having 2 to 15, 2 to 10, or 5 to 15 carbon atoms.

When the layer of the second material is a back layer, the layer may be thicker than the layer comprising the two-dimensional material. In one embodiment, the back side layer is 1 micron to 10 microns thick. In another embodiment, the back side layer is 5 microns to 10 microns thick. In one embodiment, the layer provides a substrate for a two-dimensional layer of material. In one embodiment, the back side layer is a growth substrate on which graphene or other two-dimensional material is grown. In one embodiment, the growth substrate is a metal growth substrate. In one embodiment, the metal growth substrate is a substantially continuous metal layer, rather than a mesh or mesh. Metal growth substrates compatible with the growth of graphene and graphene-based materials, including transition metals and alloys thereof. In some embodiments, the metal growth substrate is a copper-based or nickel-based substrate. In some embodiments, the metal growth substrate is copper or nickel. In another embodiment, the back side layer may be a secondary substrate to which graphene or other two-dimensional material has been transferred after growth.

In some embodiments, the ion energy ranges from 0.01keV to 10keV, 0.5keV to 10keV, 0.75keV to 10keV, 1keV to 5keV, 2keV to 10keV, or 5keV to 10 keV. In some embodiments, ion energies in excess of 0.75keV or 1keV are preferred when the two-dimensional material comprises a thin layer of graphene base material and further comprises at least some non-graphene carbon-based material. In some embodiments, the ion source provides ion doses to the multilayer material in a range from 1x10¹⁰Ion/cm²To 1x10¹⁷Ion/cm²From 1x10¹¹Ion/cm²To 1x10¹⁵Ion/cm²Or from 1x10¹³Ion/cm²To 1x10¹⁹Ion/cm². In one embodiment, the ion dose is adjusted on an ion basis, with higher doses being provided for lighter ions (lower mass ions). In some embodiments, the ion flux or ion beam current density ranges from 0.1nA/mm²To 100nA/mm²From 0.1nA/mm²To 10nA/mm²、0.1nA/mm²To 1nA/mm²From 1nA/mm²To 10nA/mm²Or from 10nA/mm²To 100nA/mm²。

In various embodiments, the two-dimensional material comprises a thin layer of graphene matrix material. In one embodiment, the first layer comprises a thin layer of graphene matrix material. In one embodiment, the thin layer of graphene-based bulk material is a single or multi-layer graphene thin layer, or a thin layer containing a plurality of interconnected single or multi-layer graphene domains. In some embodiments, the multi-layer graphene domain has 2 to 5 layers or 2 to 10 layers. In one embodiment, the layer comprising the thin layer of graphene-based body material further comprises a non-graphene carbon-based material on a surface of the thin layer of graphene-based body material. In one embodiment, the amount of non-graphene carbon-based material is less than the amount of graphene. In some embodiments, the amount of graphene in the graphene base material is from 60% to 95% or from 75% to 100%.

In some embodiments, the characteristic dimension of the perforations is from 0.3 to 10nm, from 0.3 to 0.5nm, from 0.4 to 10nm, from 0.5 to 2.5nm, from 0.5 to 10nm, from 5nm to 20nm, from 0.7nm to 1.2nm, from 10nm to 50nm, from 50nm to 100nm, from 50nm to 150nm, or from 100nm to 200 nm. In one embodiment, the average pore size is within a particular range. In some embodiments, 70% to 99%, 80% to 99%, 85% to 99%, or 90 to 99% of the perforations fall within the specified range, but other apertures fall outside the specified range. Holes falling outside of a particular range may be referred to as "non-selective" if they are larger than holes falling within the particular range.

In more specific embodiments, the method mayTo include: providing a thin layer of graphene base material on a metal growth substrate; exposing the thin layer of graphene matrix material to an ion source providing an ion dose ranging from 1x10¹⁰Ion/cm²To 1x10¹⁷Ion/cm²From 1x10¹¹Ion/cm²To 1x10¹⁵Ion/cm²Or from 1x10¹³Ion/cm²To 1x10¹⁹Ion/cm²And having an ion energy range from 0.75keV to 10keV, from 1keV to 5keV, from 2keV to 10keV, or from 5keV to 10 keV; interacting a plurality of ions and/or neutralizing ions from an ion source with the graphene and with the metal growth substrate, wherein the ions introduce a plurality of defects in the graphene and the ions and/or neutralizing ions interact with the metal growth substrate such that a plurality of layer fragments are ejected from the metal growth substrate towards the graphene; and expanding the defects in the graphene with the layer fragments to form a plurality of holes in the graphene. The metal growth substrate is disposed on the opposite side of the graphene from the ion source and constitutes a back layer. In one embodiment, when the layer is a metal growth substrate, the layer fragments constitute metal atoms or metal ions.

In other more specific embodiments, the method comprises: exposing the thin layer of graphene base material having the front layer thereon to an ion source providing an ion dose in the range from 1x10¹⁰Ion/cm²To 1x10¹⁷Ion/cm²From 1x10¹¹Ion/cm²To 1x10¹⁵Ion/cm²Or from 1x10¹³Ion/cm²To 1x10¹⁹Ion/cm²And having an ion energy range from 0.75keV to 10keV, from 1keV to 5keV, from 2keV to 10keV, or from 5keV to 10 keV; a plurality of ions and/or neutralizing ions from the ion source interact with the graphene and with the front layer, thereby introducing a plurality of defects in the graphene. In one embodiment, the ions and/or neutralizing ions are in contact with the front layerCauses ejection of a large number of layer fragments into the graphene and uses the layer fragments to expand the defects in the graphene, thereby forming a plurality of holes in the graphene. The front layer is disposed on the same side of the graphene as the ion source.

In still other more specific further embodiments, the method may comprise: exposing the graphene base material on the back side layer to an ion source providing an ion dose in the range from 1x10¹⁰Ion/cm²To 1x10¹⁷Ion/cm²From 1x10¹¹Ion/cm²To 1x10¹⁵Ion/cm²Or from 1x10¹³Ion/cm²To 1x10¹⁹Ion/cm²And having an ion energy range from 0.75keV to 10keV, from 1keV to 5keV, from 2keV to 10keV, or from 5keV to 10 keV; a plurality of ions and/or neutralizing ions from the ion source interact with the graphene and with the back layer, thereby introducing a plurality of defects in the graphene. The back layer is located on one side of the graphene and faces away from the ion source. In one embodiment, the back layer disperses the impact energy of ions and/or neutralizing ions with the back layer to the graphene region around the defects formed by the reaction of the ions and/or neutralizing ions with the graphene and promotes the defects to expand into pores.

The foregoing has outlined rather broadly the features of the present disclosure in order that the detailed description that follows may be better understood. Additional features and advantages of the invention will be described hereinafter. These and other advantages and features will become more apparent from the following description taken in conjunction with the accompanying drawings.

Brief Description of Drawings

For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

fig. 1 and 2 show exemplary schematic views of a front layer in continuous contact with graphene or other two-dimensional material;

3A, 3B, and 3C show exemplary diagrams demonstrating how the interaction of ions with the front layer and with graphene or other two-dimensional material defines pores in the graphene or other two-dimensional material; and

fig. 4A, 4B, and 4C show exemplary diagrams demonstrating how ion interaction with a back layer and with graphene or other two-dimensional material defines pores in the graphene or other two-dimensional material.

Detailed Description

The present disclosure is directed, in part, to methods of creating a large number of pores in graphene, graphene matrix materials, or other two-dimensional materials. In one embodiment, the first layer comprises a thin layer of graphene matrix material. The graphene-based material includes, but is not limited to: single layer graphene, multi-layer graphene, or interconnected single or multi-layer graphene domains, and combinations thereof. In one embodiment, the graphene base material further includes a material formed of stacked single or multi-layer graphene thin layers. In some embodiments, the multi-layer graphene comprises 2 to 20 layers, 2 to 10 layers, or 2 to 5 layers. In some embodiments, graphene is the predominant material in the graphene matrix material. For example, the graphene matrix material comprises at least 30% graphene, or at least 40% graphene, or at least 50% graphene, or at least 60% graphene, or at least 70% graphene, or at least 80% graphene, or at least 90% graphene, or at least 95% graphene. In some embodiments, the graphene-based material comprises graphene selected from the group consisting of: from 30% to 95%, or from 40% to 80%, from 50% to 70%, from 60% to 95%, or from 75% to 100%.

As used herein, "domain" refers to a region of material in which atoms enter the crystal lattice in uniform order. The domains are uniformly ordered within their boundaries, but are distinct from adjacent domains. For example, a single crystal material has a single domain of ordered atoms. In one embodiment, at least some of the graphene domains are nanocrystals, having a domain size from 1 to 100nm or 10-100 nm. In one embodiment, at least some of the graphene domains have a domain size of more than 100nm to 1 micron, or from 200nm to 800nm, or from 300nm to 500 nm. The "grain boundaries" formed by crystal defects at the boundaries of each domain distinguish between adjacent crystal lattices. In some embodiments, the first lattice may be rotated relative to the second lattice about an axis of rotation perpendicular to the plane of the lamellae such that the two lattices differ in "lattice orientation".

In one embodiment, the thin graphene-based material layer comprises a single or multiple graphene layers, or a combination thereof. In one embodiment, the graphene-based bulk material thin layer is a single or multi-layer graphene thin layer, or a combination thereof. In another embodiment, the thin layer of graphene-based body material is a thin layer comprising a plurality of interconnected single-or multi-layer graphene domains. In one embodiment, the interconnected domains are covalently bonded together to form a thin layer. When the domain lattice orientations in the thin layer are different, the thin layer is polycrystalline.

In some embodiments, the thin layer of graphene base material has a thickness from 0.34 to 10nm, from 0.34 to 5nm, or from 0.34 to 3 nm. In one embodiment, the thin layer of graphene-based bulk material includes intrinsic defects. Unlike defects that are selectively introduced in the graphene base material thin layer or the graphene thin layer through perforation, intrinsic defects are caused by the preparation of the graphene base material. These intrinsic defects include, but are not limited to: lattice abnormalities, holes, openings, cracks or wrinkles. Lattice anomalies may include, but are not limited to: carbocyclic rings other than 6-membered (e.g., 5-, 7-, or 9-membered rings), vacancies, interstitial defects (including incorporation of non-carbon atoms into the crystal lattice), and grain boundaries.

In one embodiment, the layer comprising the thin layer of graphene base material may further comprise a non-graphene carbon-based material on a surface of the thin layer of graphene base material. In one embodiment, the non-graphene carbon-based material does not have long range order and may be classified as amorphous. In some embodiments, the non-graphene carbon-based material further comprises an element other than carbon and/or a hydrocarbon. Non-carbon elements that may be incorporated into non-graphene carbon include, but are not limited to: hydrogen, oxygen, silicon, copper and iron. In some embodiments, the non-graphene carbon-based material comprises a hydrocarbon. In some embodiments, the carbon is the predominant material in the carbon-based material that is not graphene. For example, the non-graphene carbon-based material comprises at least 30% carbon, or at least 40% carbon, or at least 50% carbon, or at least 60% carbon, or at least 70% carbon, or at least 80% carbon, or at least 90% carbon, or at least 95% carbon. In some embodiments, the non-graphene carbon-based material comprises carbon selected from the group consisting of: from 30% to 95%, or from 40% to 80%, or from 50% to 70%.

Such nanomaterials with intentionally created pores are referred to herein as "perforated graphene", "perforated graphene matrix material" or "perforated two-dimensional material". The present invention is also directed, in part, to perforated graphene, perforated graphene matrix materials, and other perforated two-dimensional materials containing a large number of pores ranging in size from 0.3nm to 10 nm. The present invention is further directed, in part, to perforated graphene, perforated graphene-based body materials, and other perforated two-dimensional materials containing a large number of pores ranging in size from about 0.3nm to about 10nm with a narrow size distribution, including but not limited to: a dimensional deviation of 1-10% or a dimensional deviation of 1-20%. In one embodiment, the characteristic dimension of the holes is from 0.5nm to 10 nm. For circular holes, the characteristic dimension is the hole diameter. In some embodiments, relative to a non-circular aperture, a characteristic dimension can be considered to be a maximum distance across the aperture, a minimum distance across the aperture, an average of the maximum and minimum distances across the aperture, or an equivalent diameter based on an area within the aperture face. As used herein, perforated graphene base materials include those materials in which non-carbon atoms have been incorporated into the edges of the pores.

As described above, conventional methods of perforating graphene and other two-dimensional materials to form a large number of pores have limitations in terms of the pore density, pore size, and pore distribution obtained. Perforated nanomaterials with small pores of effective size of about 10nm or less are particularly difficult to produce so that they have sufficient pore density and size distribution to support many intended applications. For example, failure to produce pores of a selected size and pore density can significantly impede filtration applications because selectivity and throughput can be severely compromised. Furthermore, current techniques for perforating graphene and other two-dimensional materials are believed to be unable to scale to large-scale areas (e.g., one to tens of square centimeters or more) in order to support commercial production applications.

Current methods of perforating graphene and other two-dimensional materials include chemical and physical methods. The chemical process typically involves a pore nucleation and pore growth phase. However, pore nucleation and pore growth are often difficult to separate from each other, resulting in a broad distribution of pore sizes. Physical processes typically involve the removal of atoms from a two-dimensional material planar structure with a strong force. However, physical methods are quite energy inefficient, especially in view of scaling up for commercial production. Furthermore, the energetic ions actually interact very weakly with graphene and other two-dimensional materials, which results in low yields of sputtered atoms during the stripping process.

In one embodiment, the process of energetic ion perforation of graphene, graphene-based materials, and other two-dimensional materials may be significantly enhanced by performing the perforation process with at least one layer of a second material in continuous contact with the graphene or other two-dimensional material during its exposure to a broad beam or flood source ion source. A wide beam or flood source ion source may provide significantly reduced ion flux compared to a focused ion beam. In one embodiment, the ion flux is from 0.1nA/mm²To 100nA/mm². By using a wide ion field in combination with the at least one layer in continuous contact with graphene or other two-dimensional material, significantly improved perforation in terms of small pore size, narrow size distribution and high pore density can be obtained. In one embodiment, the hole density is characterized by the spacing between holes. In one embodiment, wherein the average pore size is from 0.5nm to 2.5nm, the average spacing between pores is from 0.5nm to 5 nm. The method of the present invention is readily distinguishable from focused ion beam methods, focusingIon beam methods have higher ion fluxes and/or ion energies. The wide ion field method of the present invention is quite scalable in terms of area coverage of an industrial process. As discussed below, depending on their location, the layers in continuous contact with graphene or other two-dimensional material may affect the perforation process in several different ways.

In some embodiments, the energetic ion perforation methods described herein utilize the subtractive method of physical perforation methods while also promoting the discrete pore growth phase as chemical methods. However, unlike conventional chemical and physical perforation methods, the perforation method of the present invention advantageously distinguishes between the pore nucleation and pore growth phases while still allowing nucleation and growth to occur in a highly coordinated manner. In some embodiments, the single or multiple layers in continuous contact with graphene or other two-dimensional material allow for highly coordinated nucleation and growth. In particular, the single or multiple layers allow pore growth immediately after pore nucleation due to collisions of single incident ions with graphene or other two-dimensional materials. In the conventional method, pore nucleation and pore growth are uncoordinated. Because pore nucleation and pore growth are separate but coordinated stages in the process of the present invention, a narrow pore size distribution can be obtained. Furthermore, the method of the present invention is more advantageously suited to the production of those pores of about 10nm size or less, which is advantageous for many applications, including filtration. Further, the pore size and/or pore density may be adjusted to suit the needs of a particular application. In one embodiment, a higher energy density (fluence) or exposure time increases the number of holes (until the holes begin to overlap). Higher ion energies may increase or decrease the pore size, depending on the details of the interaction. The pore density can be adjusted by adjusting the exposure time of the graphene or other two-dimensional material to the ion source.

Thus, the method of the present invention is able to provide all three key requirements (small pore size, narrow size distribution and high pore density) for perforated graphene, graphene matrix materials and other two-dimensional materials. Furthermore, because they employ a wide ion field to achieve perforation, the present methods are advantageously scalable to large dimensional areas and can support commercial production applications.

As described above, the wide ion field used to affect perforation in embodiments of the method of the present invention provides ions having an ion energy range between 0.75keV and about 10 keV. In one embodiment, the ion energy ranges from 1keV to 10 keV. In an additional embodiment, the ion energy ranges from 1keV to 5 keV. In a further embodiment, the ion energy ranges from 2keV to 10 keV. In an additional embodiment, the ion energy ranges from 5keV to 10 keV. Some ions with energies in this range may interact weakly with graphene and other two-dimensional materials, creating point defects (both single and double vacancies) in the planar structure in the form of only 1-2 atoms removed per incident ion. In one embodiment, the holes generated by the method of the present invention produce holes of larger size than such point defects. The method of the invention, particularly the continuous contact to the layer of graphene or other two-dimensional material, enables the production of pores of larger size than would be predicted based on ion energy alone. Without wishing to be bound by any theory, the contact of the front or back layer with the two-dimensional material during ion irradiation is believed to advantageously promote defect expansion into pores of meaningful size by thermal collisions that convert high energy incident ions into graphene or other two-dimensional material. As discussed further below, such effects may be assisted in a variety of ways by a combination of energy mismatches with respect to the layers in different positions of the ion source.

Although graphene is used as the two-dimensional material in certain embodiments described herein, it should be appreciated that other two-dimensional materials may be similarly used in alternative embodiments unless otherwise specified. Thus, there is considerable flexibility in practicing the present invention to produce a particular perforated two-dimensional material having the desired properties.

In various embodiments, the method of the present invention may comprise: the two-dimensional material in continuous contact with the at least one layer is exposed to an ion source, and a plurality of ions and/or neutralizing ions from the ion source interact with the two-dimensional material and with the at least one layer. In some embodiments, the ions and/or neutralizing ions introduce a plurality of defects in the two-dimensional material, and the interaction of the ions and/or neutralizing ions with the at least one layer facilitates the defects to expand to form a plurality of pores defined in the two-dimensional material. The at least one layer is in continuous contact with the two-dimensional material when the two-dimensional material is exposed to an ion source.

In various embodiments, the two-dimensional material comprises graphene, molybdenum sulfide, or boron nitride. In a more specific embodiment, the two-dimensional material may be graphene. Graphene according to embodiments of the present invention may include: single layer graphene, multilayer graphene, or a combination thereof. Other nanomaterials with extended two-dimensional molecular structures may also constitute two-dimensional materials in various embodiments of the invention. For example, molybdenum sulfide is a representative chalcogenide having a two-dimensional molecular structure, and various other chalcogenides may constitute the two-dimensional material in embodiments of the present invention. The selection of a suitable two-dimensional material for a particular application may be determined by a number of factors, including the chemical and physical environment of the end-use application of the graphene or other two-dimensional material.

In various embodiments of the present invention, the size of the pores created in the graphene or other two-dimensional material may range from about 0.3nm to about 10 nm. In more specific embodiments, the pores can range in size from 0.5nm to about 2.5 nm. In further embodiments, the pore size is 0.3 to 0.5 nm. In a further embodiment, the pore size is 0.5 to 10 nm. In an additional embodiment, the pore size is 5nm to 20 nm. In a further embodiment, the pore size is 0.7nm to 1.2 nm. In an additional embodiment, the pore size is 10nm to 50 nm. In embodiments where a larger pore size is preferred, the pore size is from 50nm to 100nm, from 50nm to 150nm, or from 100nm to 200 nm. Pores within these size ranges are particularly advantageous for filtration applications. The size range of 0.5nm to 2.5nm is particularly effective for reverse osmosis filtration.

The contact time of the graphene or other two-dimensional material with the ion source may be in the range of about 0.1 seconds to about 120 seconds to produce an ion flux sufficient to generate these pore densities. Longer contact times can be used if desired in order to adjust the number of holes obtained in the planar structure.

In embodiments of the present invention, an ion source that induces perforation for graphene or other two-dimensional materials is considered to provide a wide ion field, also commonly referred to as a flood source ion source. In one embodiment, the flood source ion source does not include a focusing lens. In some embodiments, the ion source operates at sub-atmospheric pressure, e.g., 10^-3To 10^-5Bracket or 10^-4To 10^-6And (4) supporting. In one embodiment, the environment further includes a background quantity (e.g., about 10)^-5On the order of torr) oxygen (O)₂) Nitrogen (N)₂) Or carbon dioxide (CO)₂). As described above, in one embodiment, the ion source provides from 1x10¹⁰Ion/cm²To 1x10¹⁷Ion/cm²Has an ion energy range from 0.75keV to 10 keV. In more specific embodiments, the ion energy ranges from 1keV to 10keV or from 5keV to 10 keV. In some embodiments, the ion dose range is about 1x10¹¹Ion/cm²And about 1x10¹⁵Ion/cm²At about 1x10¹²Ion/cm²And about 1x10¹⁴Ion/cm²At about 1x10¹³Ion/cm²And about 1x10¹⁹Ion/cm²In the meantime. In one embodiment, the ion dose range is about 1x10¹⁰Ion/cm²And about 1x10¹⁷Ion/cm²In the meantime. In an additional embodiment, the ion dose range is about 1x10¹¹Ion/cm²And about 1x10¹⁵Ion/cm²In the meantime. In a further embodiment, the ion dose range is about 1x10¹³Ion/cm²And about 1x10¹⁹Ion/cm²In the meantime. In one embodiment, the flux or ion beam current density is from 10nA/nm²To 100nA/nm². At one endIn some embodiments, the ion beam may be perpendicular to the layer surface of the multilayer material (incident angle of 0 degrees), or the incident angle may be 1 to 45 degrees, 0 to 20 degrees, 0 to 15 degrees, or 0 to 10 degrees.

The ion source can provide a wide variety of ions suitable for inducing perforations in graphene, graphene matrix materials, and other two-dimensional materials. In one embodiment, the ions are singly charged. In another embodiment, the ions are multiply charged. In one embodiment, the ions are noble gas ions (ions from group 18 elements of the periodic table). In one embodiment, the ions are non-helium ions. In one embodiment, the ion is an organic ion or an organometallic ion. In one embodiment, the organic or organometallic ions have an aromatic component. In one embodiment, the organic or organometallic ion has a molecular weight of from 75 to 200 or 90 to 200. In an exemplary embodiment, ions that may be provided from an ion source to induce perforation of graphene or other two-dimensional material may include: xe (Xe)⁺Ion, Ne⁺Ion, Ar⁺Ion, cycloheptatrienium cation (C)₇H₇ ⁺) And ferrocene ion [ (C)₅H₅)₂Fe⁺]. In some embodiments, when the ion is Xe⁺Ion, Ne⁺Ion, Ar⁺Ion, the dose is 1x10¹¹Ion/cm²To 1x10¹⁵Ion/cm². In some embodiments, when the ion comprises multiple elements (e.g., troponinium and ferrocene), the energy density is 1x10¹¹Ion/cm²To 1x10¹⁵Ion/cm². In one embodiment, from 1x10 is provided¹³Ion/cm²To 1x10¹⁹Ion/cm²A dose of helium ions. The selected ions, and their energies, can determine, at least in part, the size of the resulting pores in the graphene or other two-dimensional material. In particular embodiments, the selected ions or their energies are selected so that they can eject fragments from the at least one layer towards the graphene or other two-dimensional material.

In one embodiment, the temperature of the multilayer composite is controlled during ion bombardment. In some embodiments, the temperature is controlled from-130 ℃ to 200 ℃ or from-130 ℃ to 100 ℃. In one embodiment, the temperature may be chosen such that the gas condenses on the front side of the two-dimensional material. In one embodiment, where a metal back layer is present, the temperature may be controlled from 50 ℃ to 80 ℃. The layer or layers in continuous contact with the graphene or other two-dimensional material may be a front layer or a back layer, or both. The term "front side" refers to the case where the two-dimensional material is directed toward the same side of the ion source. The term "backside" refers to the opposite side of the two-dimensional material from the ion source. Depending on its location, at least one layer may be naturally or exogenously present on the graphene or other two-dimensional material, or the at least one layer is intentionally deposited after the graphene or other two-dimensional material is formed. For example, in various embodiments of the present invention, the metal growth substrate may constitute the back side layer.

Generally, the at least one layer has a bond energy that is weaker than that of graphene or a two-dimensional material, which is characterized by strong bonds. That is, bond rupture occurs in at least one layer in preference to graphene or other two-dimensional material due to bond energy mismatch when the at least one layer interacts with the ion source. In some embodiments, the at least one layer may be a deposited layer, such as deposited silicon, deposited polymer, or a combination thereof. The deposited layer may constitute a front layer if graphene or other two-dimensional material is still present on its metal growth substrate. However, if the graphene or other two-dimensional material has been removed from its metal growth substrate, the deposited layer may constitute a front layer or a back layer. The deposition polymer may comprise any polymeric material that may suitably adhere to the graphene matrix material or other two-dimensional material, such as a siloxane polymer. In one embodiment, the deposited polymer does not completely delaminate from the graphene-based material during ion bombardment. Other suitable polymer layers are envisioned by those skilled in the art.

In some embodiments, the front layer deposited on the graphene or other two-dimensional material may have a thickness range between about 1nm to about 10 nm. Thicker facing layers may also be present if desired. Although the front layer may be deposited exogenously during graphene or other two-dimensional material synthesis, in other embodiments, the front layer may also be deposited in a separate operation. For example, in some embodiments, the front layer may be deposited by sputtering, spray coating, spin coating, atomic layer deposition, molecular beam epitaxy, or similar techniques.

The different layers will be further described in terms of their location and function.

In some embodiments, the at least one layer may be at least one front layer on the two-dimensional material on the same side as the ion source. Exemplary front layers may include those described above. When a front layer is present, ions from the ion source interact with the front layer before interacting with the graphene or other two-dimensional material. As described below, this type of interaction may still promote the creation of pores in the planar structure of graphene or other two-dimensional material as well as the expansion of pores therein by ejecting layer fragments from the front layer and impinging the layer fragments with graphene or other two-dimensional material. Because the front layer is relatively thin, it has low braking capability and allows ions and/or neutralizing ions to penetrate the front layer, thereby further interacting with the graphene.

In one embodiment, ion collisions of the front layer produce feathered, more but lower energy particles and impact the graphene or other two-dimensional material. In more specific embodiments, the method of the present invention may comprise: ejecting a plurality of layer fragments from the front layer to the two-dimensional material based on subsequent ion and/or neutralizing ion interactions; and in a region of the two-dimensional material surrounding a defect, the layer fragment collides with the two-dimensional material, and the defect is generated based on an interaction of ions and/or neutralizing ions with the two-dimensional material; and promoting the defect to expand into a pore. The layer fragment types may include atoms, ions, molecules, or molecular fragments that are released from the front layer upon interaction of energetic ions with the front layer. The front layer may be present in combination with the back layer or the front layer may be present alone. The function of the back layer will be discussed further below.

Without being bound by theory or mechanism, it is believed that the definition or creation of pores may occur based on some synergistic effect when a front layer is present. First, graphene or other two-dimensional materials have a higher chemical reactivity near the initial defects that were originally created by the energetic ions and/or neutralizing ions. Second, layer fragments from the front layer may convert a single impact event of the front layer into multiple impact events on graphene or other two-dimensional materials. Third, the layer fragments have lower energy than the incident high energy ions, thereby enhancing the likelihood of successfully interacting with graphene or other two-dimensional materials to define the pores. Finally, because the front layer and the graphene or other two-dimensional material are in continuous contact with each other, the geometric diffusion of the layer fragments is minimal during their transport to the graphene or other two-dimensional material, thereby defining the pore size. Thus, the combination of enhanced chemical reactivity in the vicinity of the defect and more efficient interaction between the layer fragments and the graphene or other two-dimensional material may result in the creation of pores.

Fig. 1 and 2 show exemplary schematic views of a front layer 2 in continuous contact with graphene 4 or other two-dimensional material. In fig. 1, only the front layer 2 is present, whereas in fig. 2 both the front layer 2 and the back layer 6 are present. The ion source 8 is configured to provide a dose of ions 10 for perforating the graphene 4.

Fig. 3A, 3B, and 3C show exemplary schematics of how ions interact with the front layer and graphene or other two-dimensional material to define pores in the graphene or other two-dimensional material. For clarity of illustration and description, the front layer 2 and graphene 4 are shown in exploded view, shown in fig. 3A and 3B as being separated, rather than in true continuous contact with each other. Fig. 3A shows the front layer 2 and graphene 4 after ions 10 have impacted and passed through the front layer. The layer fragments 12 are ejected from the front layer 2 and are scattered towards the graphene 4 at a thermal velocity/energy and/or a high thermal velocity/energy. In one embodiment, such a spray may be referred to as ballistic scattering. Defects 13 are generated in the front layer. When ions 10 pass through the planar structure of graphene 4, defects 14 (not shown in fig. 3A) may be introduced into graphene 4. Furthermore, it is emphasized that the front layer 2 and the graphene 4 are in actual continuous contact with each other, thus reducing the angle of ballistic scattering that occurs as the layer fragments 12 move from the front layer 2 to the graphene 4. In one embodiment, the layer fragments 12 impinge on the graphene 4 in close proximity to the defects 14, where the chemical reactivity is enhanced. In one embodiment, the layer fragments 12 then cause the defects 14 to expand to form holes 16, as shown in FIG. 3B. Fig. 3C shows the true continuous contact arrangement of the front layer 12 and graphene 4 after aperture 16 generation. As shown in fig. 3A-3C, the stages of pore nucleation (i.e., formation of defects in the graphene by direct interaction of ions) and pore growth (i.e., impact of layer fragments 12 on graphene 4) are separate, yet highly coordinated processes. Thus, pores 16 of a defined size and having a narrow size distribution can be obtained.

As shown in fig. 3B, front layer 2 may at least partially cover apertures 16 after aperture formation. In some embodiments, the front layer 2 may be removed after the pores 16 are defined to enhance the actual permeability of the graphene 4. Exemplary front layer removal techniques may include, for example, oxidation, solvent cleaning, heating, or combinations thereof. Oxidation techniques include, but are not limited to, ultraviolet ozone (UVO) treatment with active oxygen. Depending on the composition of front layer 2, one skilled in the art will be able to select an appropriate removal process.

In some embodiments, at least the layer in continuous contact with the graphene or other two-dimensional material is a back layer on one side of the graphene or other two-dimensional material opposite the ion source. In one embodiment, the back side layer is a metal growth substrate on which graphene or other two-dimensional material is grown, or the back side layer may be a second substrate to which graphene or other two-dimensional material is transferred after growth. In one embodiment, the second substrate is polymeric and comprises a porous polymeric membrane. In another case, the back side layer may have a thickness significantly greater than graphene or other two-dimensional material. Thus, the back side layer may have a higher braking capability for energy ions and/or neutralizing ions than graphene or other two-dimensional materials. Once the energetic ions are stopped, the back layer may disperse the impact energy of the ions and/or neutralizing ions of the back layer into regions of graphene or other two-dimensional material near the created defects as the ions interact with the two-dimensional material to form defects, thereby promoting the defects to expand into pores. In more specific embodiments, the back layer promotes the expansion of defects in the two-dimensional material into holes in a manner somewhat similar to the front layer described above, with debris directed toward the two-dimensional material. The back layer may also promote the formation of defects in the two-dimensional material. For example, even when ions or neutralizing ions do not create pores when passing through a two-dimensional material, the impact of the ions and/or neutralizing ions on the back layer may cause a small area of the back layer to rapidly heat up and expand, thereby opening pores in the graphene or other two-dimensional material.

Fig. 4A, 4B, and 4C show exemplary diagrams demonstrating how the interaction of ions with the back layer and graphene or other two-dimensional material defines pores in the graphene or other two-dimensional material. Furthermore, for clarity of illustration and description, the back side layer 6 and graphene 4 are shown in exploded view, shown in fig. 4A and 4B in a separated manner, rather than in true continuous contact with each other. Fig. 4A shows the graphene 4 or other two-dimensional material and the back layer 6 immediately after ions have passed through the graphene 4 and impacted the back layer 6. When the ions pass, defects 14 are generated in the graphene 4. As for the back layer 6, ions are embedded in the impact region 20, thus producing a jet of layer fragments 12' therefrom. In fig. 4A, the impact area 20 is shown as a pit. The layer fragments 12' may comprise those species as described above with respect to the front layer 2. For example, when the back side layer 6 is a metal growth substrate on which the graphene 4 or other two-dimensional material is grown, the layer fragments 12' may be metal atoms or metal ions sputtered from the metal growth substrate when kinetic energy is transferred from the ions to the back side layer 6. The layer fragments 12' are ejected at a thermal energy velocity towards the graphene 4 and again impinge the defect 14 in close proximity such that it expands into a pore 16, as depicted in fig. 4B. In the arrangement of fig. 4A and 4B, the layer fragments 12' strike the graphene 4 from below, rather than from its top surface as depicted in fig. 3A and 3B. Furthermore, it is emphasized that the back layer 6 and the graphene 4 are in fact on a continuous basis with each other, thus reducing the angle of scattering that occurs when the layer fragments 12' are transferred from the back layer 6 to the graphene 4. As shown, the layer fragments 12' impinge closely adjacent the defect 14, where the chemical reactivity is enhanced. Fig. 4C shows the true continuous contact structure of the back side layer 6 and the graphene 4 after the hole 16 is created. As shown in fig. 4A-4C, the pore nucleation stage (i.e., formation of defects 14) and pore growth (i.e., impingement of layer fragments 12' on graphene 4) are again separated, yet are highly coordinated processes. Since there is minimal geometrical scattering when the layer fragments 12' are transferred between the back layer 6 and the graphene 4, pores 16 with defined size and narrow size distribution can be obtained.

Exemplary metal growth substrates for growing graphene, graphene-based materials, and other two-dimensional materials, and which may serve as back side layers in embodiments of the present invention, include various metal surfaces containing transition metals. For graphene, for example, copper or nickel may be particularly effective in promoting epitaxial graphene growth. In some embodiments, the metal growth substrate may be formed substantially entirely of metal, such as a metal foil or a metal plate. In other embodiments, the metal growth substrate may include a metal surface on a different subsurface material. For example, in an embodiment of the present invention, a ceramic substrate having a metal surface may be used as the metal growth substrate and the back side layer.

Thus, in some embodiments, the methods of the present invention may comprise: upon interaction of ions and/or neutralizing ions with the two-dimensional material, a plurality of layer fragments are ejected from the back layer toward the two-dimensional material (e.g., graphene), and the two-dimensional material is impacted with the layer fragments in an area of the two-dimensional material surrounding the defect, thereby promoting expansion of the defect into a pore. That is, the back layer may facilitate the transfer of energy to the graphene or other two-dimensional material in the form of layer fragments having thermal velocities, thereby facilitating the formation of holes in the graphene or other two-dimensional material.

In some embodiments, both the front and back layers may be in continuous contact with graphene or other two-dimensional material when it interacts with ions from an ion source and/or neutralizing ions. The layer fragments generated from the front and back layers may act in concert with each other to expand defects generated in the graphene or other two-dimensional material into a large number of voids. For example, in some embodiments, the layer fragments generated from the appropriate front layer and the metal atoms and metal ions generated from the back metal growth substrate may impact the graphene from both sides of its planar structure to promote the generation of pores therein. This is particularly effective for perforated multilayer two-dimensional materials (e.g. multilayer graphene), for example by keeping the particles in a local area.

Thus, in embodiments where both a front layer and a back layer are present, the method of the present invention may comprise: the method includes ejecting a plurality of layer fragments from the front layer to the graphene or other two-dimensional material based on interaction of ions and/or neutralizing ions therewith, and ejecting a plurality of layer fragments from the back layer to the graphene or other two-dimensional material based on interaction of ions and/or neutralizing ions therewith, and the layer fragments from the two layers collide with the graphene or other two-dimensional material in a region surrounding a defect, which is generated by interaction of ions and/or neutralizing ions with the graphene or other two-dimensional material, and promote expansion of the defect into pores.

In particular embodiments, the method of the present invention may comprise: providing graphene on a metal growth substrate; exposing graphene to an ion source; interacting a plurality of ions from an ion source with the graphene and the metal growth substrate, thereby introducing a plurality of defects in the graphene; and, ions and/or neutralizing ions withThe interaction of the metal growth substrates causes the graphene to be sprayed with a plurality of layer fragments containing metal ions or metal atoms from the metal growth substrates; and expanding the defects in the graphene with the layer fragments to define a plurality of holes in the graphene. In one embodiment, the ion source provides a dose of ions to the graphene in a range of about 1x10¹¹Ion/cm²And about 1x10¹⁷Ion/cm²And has an ion energy range between about 0.75keV and about 10 keV. The metal growth substrate is located on one side of the graphene, which faces away from the ion source, and forms a back layer.

In some embodiments, the graphene surface is coated with a front layer on the opposite side of the metal growth substrate, the front layer being on the same side of the graphene as the ion source (see, e.g., fig. 2). The front layer may be formed of different materials and may have a thickness ranging, for example, between about 1nm and about 10 nm. In some embodiments, the method may further comprise: after a large number of pores are formed in the graphene, the front layer is removed.

In other particular embodiments, the method of the present invention may comprise: exposing graphene to an ion source, the graphene having a front layer thereon on the same side of the graphene as the ion source; interacting a plurality of ions and/or neutralizing ions from an ion source with the graphene and the front layer to introduce a plurality of defects in the graphene; and, the interaction of the ions and/or neutralizing ions with the front layer results in the ejection of a large number of layer fragments to the graphene; and expanding the defects in the graphene with the layer fragments to define a plurality of pores in the graphene. In one embodiment, the ion source provides graphene in a range of about 1x10¹¹Ion/cm²And about 1x10¹⁷Ion/cm²And having an ion energy range between about 0.75keV and about 10 keV.

In another particular embodiment, the method of the present invention may comprise: exposing graphene, present on one side of the graphene, to an ion sourceA back layer facing away from the ion source; interacting a plurality of ions and/or neutralizing ions from an ion source with the graphene and the back side layer to introduce a plurality of defects in the graphene; and, the interaction of the ions and/or neutralizing ions with the back layer, resulting in dispersing impact energy of the ions and/or neutralizing ions on the back layer into the graphene region surrounding the defects resulting from the interaction of the ions with the graphene; and promoting expansion of these defects into pores. In one embodiment, the ion source provides graphene in a range of about 1x10¹⁰Ion/cm²And about 1x10¹⁷Ion/cm²And having an ion energy range between about 0.75keV and about 10 keV.

In more particular embodiments, the method of the present invention may comprise: exposing graphene to an ion source, wherein a back layer is present in the graphene on one side of the graphene and facing away from the ion source; interacting a plurality of ions and/or neutralizing ions from an ion source with the graphene and the back side layer to introduce a plurality of defects in the graphene; and, the interaction of the ions and/or neutralizing ions with the back layer results in the ejection of a large number of layer fragments to the graphene; and expanding the defects in the graphene with the layer fragments to define a plurality of pores in the graphene. In one embodiment, the ion source provides graphene in a range of about 1x10¹⁰Ion/cm²And about 1x10¹⁷Ion/cm²And having an ion energy range between about 0.75keV and about 10 keV.

The perforated graphene, graphene matrix materials, and other two-dimensional materials described herein may be used in many applications, including filtration, the electronics industry, barrier and thin films, gas barriers, and the like. Exemplary filtration applications that can use perforated graphene, graphene matrix materials, and other perforated two-dimensional materials include: such as reverse osmosis, molecular filtration, ultrafiltration and nanofiltration processes. When used in different filtration processes, the perforated graphene or other perforated two-dimensional material may be perforated and then transferred to a porous second substrate, where the perforated graphene or other perforated two-dimensional filtration is used as an active filtration membrane.

Although the present invention has been described with reference to the disclosed embodiments, those skilled in the art will readily appreciate that these are only examples of the present invention. It will be understood that various modifications may be made without departing from the spirit of the invention. The invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description.

The invention may be practiced using any combination of the described or illustrated concepts or components, unless otherwise specified. The specific names of the compounds are intended to be exemplary, as it is well known that one skilled in the art may additionally name these same compounds. When a compound as described herein, for example, in a chemical formula or in a chemical name, does not specify a particular isomer or enantiomer of the compound, the description is intended to include each isomer and each enantiomer, alone or in any combination, of the compound. Those skilled in the art will understand that methods, equipment components, starting materials, and synthetic methods other than those specifically identified can be used in the practice of the present invention without undue experimentation. All known functional equivalents of any such methods, equipment components, starting materials, and synthetic methods are intended to be encompassed by the present invention. Whenever a range, such as a temperature range, time range, or composition range is given in the specification, all intermediate regions and subranges, as well as all individual values included in the given range, are intended to be included in the invention. If a Markush group or other group is used herein, all individual components and all possible combinations and subcombinations of the groups are intended to be encompassed by the invention.

As used herein, "comprising" is synonymous with "including," "containing," or "characterized by," and is compatible or open-ended and does not exclude additional, unrecited components or method steps. As used herein, "comprising" excludes any element, step, or component not specified in the claims. As used herein, "consisting essentially of …" does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claims. Any recitation herein of the term "comprising", particularly in the context of a description of a component of a composite or a component of a device, is understood to encompass composites and methods consisting essentially of, and consisting of, those components or elements. The invention illustratively described herein suitably may be practiced in the absence of any element or elements, or any limitation or limitations, which is not specifically disclosed herein.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred examples of optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.

Generally, the terms and phrases used herein have meanings known in the art, which may be determined by reference to standard texts, journal articles and contexts known to those skilled in the art. The foregoing definitions are provided to clarify their specific application in the context of the present invention.

Throughout this application, all references, such as patent documents (including issued or granted patents or equivalents thereof), patent application publications; and non-patent documents or other source materials, which are incorporated by reference herein in their entirety, to the extent that each reference is at least partially inconsistent with the disclosure of this application (e.g., partially inconsistent references are incorporated by reference herein, except for the partially inconsistent reference).

All patents and publications mentioned in the specification are indicative of the levels of those skilled in the art to which the invention pertains. The references cited herein are incorporated by reference in their entirety to indicate the state of the art as of filing date in certain instances, and such information can be used herein if desired and to exclude (e.g., discard) particular embodiments of the prior art if desired. For example, when a compound claim is claimed, it is understood that compounds known in the art, including the specific compounds disclosed in the references (especially in the cited patent documents), are not intended to be encompassed by the claim.

Claims

1. A method, comprising:

exposing a multilayer material to ions provided by an ion source, the multilayer material comprising a first layer comprising a two-dimensional first material, and a second layer of a second material in contact with the first layer, the provided ions having an ion energy ranging from 1.0keV to 10keV and from 0.1nA/mm²To 100nA/mm²The flux of (a); and

a plurality of holes are created in the two-dimensional first material by interacting a plurality of ions, neutralizing ions, or a combination thereof provided by an ion source with the two-dimensional first material and with a second material.

2. The method of claim 1, wherein the ion energy is from 1.0keV to 5 keV.

3. The method of claim 1, wherein the ion source is a broad beam source.

4. The method of claim 1, wherein the multilayer material is exposed to from 1x10¹¹Ion/cm²To 1x10¹⁵Ion/cm²A range of ion doses, and the ion source provides ions selected from the group consisting of: xe (Xe)⁺Ion, Ne⁺Ions or Ar⁺Ions.

5. The method of claim 1, wherein the multilayer material is exposed to from 1x10¹¹Ion/cm²To 1x10¹⁵Ion/cm²And the ion source provides organic or organometallic ions having a molecular weight of from 90 to 200.

6. The method of claim 5, wherein the ions are selected from the group consisting of: cycloheptatrienium ions and ferrocene ions.

7. The method of claim 1, wherein the two-dimensional first material comprises graphene.

8. The method of claim 7, wherein the first layer comprises a thin layer of graphene matrix material.

9. The method of claim 1, wherein the pores have a characteristic size of from 0.5nm to 2.5 nm.

10. The method of claim 1, wherein the pores have a characteristic size of from 1nm to 10 nm.

11. The method of any of claims 1-10, wherein the first layer has a first side and a second side, wherein the first side faces the ion source, and wherein the second layer is located on the second side of the first layer and has a thickness greater than the first layer.

12. The method of claim 11, wherein the second material comprises a metal.

13. The method of claim 12, wherein the second layer comprises a metal growth substrate for the two-dimensional first material, and the debris comprises metal atoms or metal ions ejected from the metal growth substrate.

14. The method of claim 11, wherein the interaction of at least a portion of the ions, neutralizing ions, or a combination thereof with the first material introduces a plurality of defects in the first material; a plurality of ions, neutralizing ions, or a combination thereof pass through the first layer comprising the first material and interact with the second material, and the interaction of the ions, neutralizing ions, or a combination thereof with the second material of the second layer promotes the expansion of the defects into pores.

15. The method of claim 14, wherein the second material interacts with the ions, neutralizing ions, or a combination thereof, thereby producing fragments of the second material, wherein at least some of the fragments from the second material are directed toward the two-dimensional material.

16. The method of claim 11, wherein the multi-layer material further comprises a third layer of a third material on the first side of the first layer, the third layer having an average thickness ranging from 1nm to 10 nm.

17. The method of claim 16, wherein the third layer comprises depositing silicon, depositing a polymer, condensing a gas, condensing an organic compound, or a combination thereof.

18. The method of claim 16, wherein a plurality of ions, neutralizing ions, or a combination thereof pass through the third layer of the third material to interact with the first material; the interaction of the ions, neutralizing ions, or combinations thereof with the first material (2D) introduces a plurality of defects in the first material, the plurality of ions, neutralizing ions, or combinations thereof pass through the first layer comprising the first material and interact with the second material, and the interaction of at least a portion of the ions, neutralizing ions, or combinations thereof with the second material and the third material promotes expansion of the defects into pores.

19. The method of claim 18, wherein the third material interacts with ions, neutralizing ions, or a combination thereof, thereby producing fragments of the third material, at least some of the fragments from the third material being directed toward the two-dimensional material.

20. The method of any of claims 1-10, wherein the first layer has a first side and a second side, wherein the first side faces the ion source, and wherein the second layer is located on the first side of the first layer and has an average thickness from 1nm to 10 nm.

21. The method of claim 20, wherein the second layer comprises depositing silicon, depositing a polymer, condensing a gas, condensing an organic compound, or a combination thereof.

22. The method of claim 20, wherein a plurality of ions, neutralizing ions, or a combination thereof pass through the second layer of the second material, interact with the two-dimensional material; the interaction of the ions, neutralizing ions, or combination thereof with the first material introduces a plurality of defects in the first material; and interaction of at least a portion of the ions, neutralizing ions, or combinations thereof with the second material, facilitating expansion of the defects into pores.

23. The method of claim 22, wherein the second material interacts with ions, neutralizing ions, or a combination thereof, thereby creating fragments of the second material, at least some of the fragments from the second material being directed toward the first material.