Multi-atomic layered materials

Abstract

A multi-atomic layered material and methods of making and using the same are described. The material can include a first 2D non-carbon mono-element atomic layer, a second 2D non-carbon mono-element atomic layer, and intercalants positioned between the first and second atomic layers.

Claims

1. A multi-atomic layered material comprising a first 2D mono-element atomic layer, a second 2D mono-element atomic layer, and intercalants positioned between the first and second atomic layers, wherein the first and second atomic layers have an inter-layer spacing and are bonded held together by van der Waals forces or sp3-hybridized bonding, or both; wherein the first and second atomic layers are each individually a silicene atomic layer, a germanene atomic layer, a stanene atomic layer, a phosphorene atomic layer, a lead atomic layer, or a borophene atomic layer; and wherein the intercalants are affixed between the first and second atomic layers; and wherein the intercalants are selected from the group consisting of polymers, block copolymers, polymer brushes, carbon-based intercalants, metal organic frameworks, zeolitic imidazolated frameworks, covalent organic frameworks, ionic liquids, liquid crystals, atomic clusters and nanoparticles comprising a metal or an oxide or alloy thereof, or any combination thereof, wherein the metal is selected from the group consisting of palladium (Pd), platinum (Pt), gold (Au), rhodium (Rh), ruthenium (Ru), rhenium (Re), osmium (Os), iridium (Ir) silver (Ag), copper (Cu), iron (Fe), nickel (Ni), zinc (Zn), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W), tin (Sn), boron (B), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), polonium (Po), or combinations thereof.

2. The multi-atomic layered material of claim 1, wherein the first and second atomic layers are each individually a silicene atomic layer, a germanene atomic layer, a stanene atomic layer, and have an inter-layer spacing.

3. The multi-atomic layered material of claim 1, wherein the first and second atomic layers are each individually a silicene atomic layer, a germanene atomic layer, a stanene atomic layer, a lead atomic layer, or a borophene atomic layer.

4. The multi-atomic layered material of claim 3, wherein the first and second atomic layers are both: silicene atomic layers; germanene atomic layers; stanene atomic layers; lead atomic layers; or borophene atomic layers.

5. The multi-atomic layered material of claim 3, wherein the first and second atomic layers are different.

6. The multi-atomic layered material of claim 3, wherein the first or second atomic layers, or both layers, are functionalized.

7. The multi-atomic layered material of claim 1, the intercalant is an atomic cluster or nanoparticle comprising a metal or an oxide or alloy thereof, wherein the metal is selected from the group consisting of palladium (Pd), platinum (Pt), gold (Au), rhodium (Rh), ruthenium (Ru), rhenium (Re), osmium (Os), iridium (Ir) silver (Ag), copper (Cu), iron (Fe), nickel (Ni), zinc (Zn), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W) and tin (Sn), or combinations thereof.

8. The multi-atomic layered material of claim 1, wherein the first and second atomic layers are both: silicene atomic layers and the intercalant is Au.

9. The multi-atomic layered material of claim 1, wherein the intercalants are polymers, block copolymers, polymer brushes, carbon-based intercalants, metal organic frameworks, zeolitic imidazolated frameworks, covalent organic frameworks, ionic liquids, liquid crystals, or atomic clusters or nanoparticles comprising a metal or an oxide or alloy thereof, or any combination thereof.

10. The multi-atomic layered material of claim 9, wherein the metal is a noble metal or a transition metal or a combination or alloy or oxide thereof; wherein the metal is selected from the group consisting of palladium (Pd), platinum (Pt), gold (Au), rhodium (Rh), ruthenium (Ru), rhenium (Re), osmium (Os) and iridium (Ir), or any combinations or alloys thereof.

11. The multi-atomic layered material of claim 1, wherein the first and second atomic layers are oxidized.

12. The multi-atomic layered material of claim 1, wherein the first and second atomic layers are non-oxidized.

13. The multi-atomic layered material of claim 1, wherein the material further comprises a 2D atomic layer of graphene, graphyne, or graphane.

14. A device comprising the multi-atomic layered material of claim 1, the device comprising an energy storage/conversion/transport device, a sensor, a flexible sensor, an electronic device, an optoelectronic device, an optical device, a photo device, a thermal device, a coating material, or a catalyst.

15. A method of making any one of the multi-atomic layered materials of claim 1, the method comprising: (a) obtaining a liquid composition comprising a multi-atomic layered mono-element stack dispersed therein; (b) exfoliating the multi-atomic layered mono-element stack in the liquid composition in the presence of a intercalant or a precursor thereof; and (c) allowing liquid solution to stand for greater than 10 hours, wherein the exfoliated multi-atomic layered mono-element stack re-aggregates and positions the intercalant or precursor thereof between at least a first 2D non-carbon mono-element atomic layer and a second 2D non-carbon mono-element atomic layer of the stack to obtain the multi-atomic layered material.

16. The multi-atomic layered material of claim 1, wherein the material further comprises a 2D atomic layer of graphyne.

17. The multi-atomic layered material of claim 1, wherein the material further comprises a 2D atomic layer of graphane.

18. The multi-atomic layered material of claim 1, wherein the intercalants are polymers.

19. The multi-atomic layered material of claim 1, wherein the material further comprises a 2D atomic layer of graphene.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Advantages of the present invention may become apparent to those skilled in the art with the benefit of the following detailed description and upon reference to the accompanying drawings.

(2) FIGS. 1A and 1B are schematics showing a multi-atomic layered non-carbon mono-element stack dispersed in a fluid medium in the presence of a plurality of intercalant(s) (FIG. 1B) and/or precursor(s) thereof (FIG. 1A).

(3) FIGS. 2A and 2B are schematics of a fully exfoliated (FIG. 2A) and a partially exfoliated (FIG. 2B) multi-atomic layered non-carbon mono-element stacks dispersed in a fluid medium in the presence of a plurality of intercalant(s) and/or precursor(s) thereof.

(4) FIG. 3 is a schematic of a fully exfoliated multi-atomic layered non-carbon mono-element stack dispersed in a fluid medium in the presence of a plurality of intercalant(s) and/or precursor(s) there wherein the intercalants(s) and/or precursor(s) thereof have been immobilized to or functionalized the surface(s) of the exfoliated mono-element single-layer and/or few-layer stacks.

(5) FIG. 4 is a schematic of a fully exfoliated multi-atomic layered non-carbon mono-element stack with intercalant(s) and/or precursor(s) immobilized to the surface and whose layers were allowed to restack, resulting in a multi-layered stack with intercalant(s) and/or precursor(s) thereof are positioned between or immobilized between each multi-atomic non-carbon mono-element layer.

(6) FIG. 5A is a schematic of an fully exfoliated multi-atomic layered non-carbon mono-element stack whose surface has been functionalized in the manner depicted in FIG. 3 and whose layers were allowed to restack, resulting in a multi-layered stack with intercalants(s) and/or precursor(s) thereof are positioned between or immobilized between some—but not all—multi-atomic non-carbon mono-element layers.

(7) FIG. 5B is a schematic of a partially exfoliated multi-atomic layered non-carbon mono-element stack with intercalant(s) and/or precursor(s) positioned between or immobilized between multi-atomic non-carbon mono-element layers.

(8) FIG. 6 is a schematic of an exfoliated multi-atomic layered non-carbon mono-element stack whose layers were allowed to restack, resulting in a multi-layered stack with precursors positioned between or immobilized between each layer.

(9) FIG. 7A is a schematic of method to prepare an exfoliated multi-atomic layered non-carbon mono-element stack of the present invention.

(10) FIG. 7B is a schematic of a method to prepare an exfoliated functionalized multi-atomic layered non-carbon mono-element stack of the present invention.

(11) FIG. 8 is a schematic of an embodiment of a system that can be used to perform chemical reactions with the multi-layered material of the present invention.

(12) FIG. 9 is a scanning electron microcopy (SEM) image of CaSi.sub.2 after KOH treatment.

(13) FIG. 10 is a SEM image of the precipitated material immediately after ending the sonication of CaSi.sub.2.

(14) FIG. 11 is a SEM image of the precipitate twenty-four hours after sonication of CaSi.sub.2.

(15) FIG. 12 is a SEM image of the precipitate twenty-four hours after sonication of CaSi.sub.2 used for EDS analysis.

(16) FIG. 13 is a SEM image of the CaSi.sub.2 after KOH treatment.

(17) FIG. 14 is a transmission electron microscopy (TEM) image of the precipitate twenty-four hours after sonication of CaSi.sub.2.

(18) FIG. 15 depicts an XRD pattern of the precipitate twenty-four hours after sonication of CaSi.sub.2.

(19) FIG. 16 is a Raman spectra of the precipitate twenty-four hours after sonication of CaSi.sub.2.

(20) FIG. 17 is a Raman spectra of the CaSi.sub.2 starting material after KOH treatment.

(21) While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and may herein be described in detail. The drawings may not be to scale.

DETAILED DESCRIPTION OF THE INVENTION

(22) A solution that overcomes the problems associated with producing and using intercalated 2D non-carbon mono-element multi-atomic layered material has been discovered. The solution is premised on a process that enables the production of multi-atomic layered materials with intercalant(s) and/or precursor(s) thereof intercalated between 2D non-carbon mono-element atomic layers. The non-carbon mono-element atomic layers can be silicene atomic layers, germanene atomic layers, stanene atomic layers, phosphorene atomic layers, borophene atomic layers, lead atomic layers, or combinations thereof. Without wishing to be bound by theory, it is believed that exfoliating 2D non-carbon mono-element multi-layered stacks in the presence of intercalant(s) and/or precursor(s) thereof allows the intercalant(s) and/or precursor(s) to affix to the surface of the exfoliated layers. This affixation is believed to stabilize the sp.sup.3 hybridized bonding orbitals on the exposed exfoliated surfaces, which can—if left unpassivated—result in irreversible self-aggregation and/or self-folding, rendering the material potentially un-useful with regards to target applications. Re-aggregation of the exfoliated layers can then result in the materials of the present invention.

(23) These and other non-limiting aspects of the present invention are discussed in further detail in the following sections with reference to the Figures.

(24) A. Intercalated 2D Non-Carbon Mono-Element Multi-Atomic Layered Material

(25) The intercalated 2D non-carbon mono-element multi-atomic layered material of the present invention includes a multi-atomic layered material that includes a first 2D non-carbon mono-element atomic layer, a second 2D non-carbon mono-element atomic layer, and intercalant(s) or precursor(s) thereof positioned between the first and second atomic layers.

(26) 1. Mono-Element Atomic Layers

(27) The mono-element atomic layers can be drawn from a monolithic parent substrate of the same material. Such parent substrates can be included—in whole or in part—of either Si, Ge, Sn, P, Pb, or B, provided that the composition of the layers is confined to a single element in the final material. In some embodiments, suitable parent substrate material can include monolithic slabs, chunks, or stacks of the target material (i.e., Si, Ge, Sn, P, Pb, or B). In other instances, the parent substrate from which the mono-element atomic layers are drawn may be multi-element compounds, non-limiting examples of which include SiM, GeM, SnM, PM, and BM, where M is a Column 1 metal (e.g., lithium (Li), sodium (Na), potassium (K)) or a Column 2 metal (e.g., magnesium (Mg), calcium (Ca)). In some embodiments, each dimension of the parent substrate may range from 1 nanometer (nm) to 10 millimeters (mm) (10.sup.7 nm) in size. In preferred embodiments, each dimension can range from 10 nanometers to 1 millimeter in size. In more preferred embodiments, each dimension can range from 100 nanometers to 100 micrometers (“microns”).

(28) In some embodiments, single parent substrate material can be used. In other instances, a plurality of parent substrate materials can be used. For example, Si and Ge parent substrates can be used together to generate a 2D non-carbon mono-element multi-atomic layered material with intercalant(s) and/or precursor(s) thereof intercalated throughout, where the final material has alternating layers of both Si and Ge, wherein the frequency with which the layers alternate is either uniform (i.e., Si/Ge/Si/Ge), or variable (i.e., random). In embodiments where a single parent substrate substance is used, graphene, graphane, and graphyne are excluded from the list from which 2D mono-element layers may be drawn. In other embodiments where a plurality of parent substrates are used to produce the final material, graphene (along with graphane and graphyne) can be included in the list from which 2D mono-element layers may be drawn. Stated another way, graphene is not used by itself as a source of 2D mono-element layers, but graphene, TMDs, MXenes or any other 2D mono-element can be used as a source of 2D mono-element layers if done so in combination with one or more of either Si, Ge, Sn, P, Pb, or B parent substrates. In some embodiments, Zintl phases are used as the parent substrate. A Zintl phase can be the reaction product of Column 1 or 2 metals and a Column 13-16 metal or metalloid. Non-limiting examples of Zintl phases include calcium disilicide (CaSi.sub.2), NaTl, or the like.

(29) 2. Intercalant(s) and Precursor(s) Suitable for Intercalation

(30) The intercalant(s) can include any material having a size, which allows it to intercalate between two layers of the 2D multi-atomic layered material. Non-limiting examples of an intercalant include a metal, a metal oxide, a carbon-based intercalant, a metal organic framework, a zeolitic imidazolated framework, a covalent organic framework, ionic liquids, liquid crystals, or atomic clusters or nanoparticles comprising a metal or an oxide or alloy thereof. The metal can be a noble metal (e.g., palladium (Pd), platinum (Pt), gold (Au), rhodium (Rh), ruthenium (Ru), rhenium (Re), osmium (Os) or iridium (Ir), or any combinations or alloys thereof, or a transition metal (e.g., silver (Ag), copper (Cu), iron (Fe), nickel (Ni), zinc (Zn), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W), or tin (Sn), or any combinations or oxides or alloys thereof. In other instances, the intercalant(s) can include a metalloid or a semiconductor element(s), such as boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), polonium (Po) or derivatives thereof, or combinations thereof. In still other instances, the intercalant(s) may be comprised of compound semiconductors compounds from Columns 12-16, 13-15, or 14-16 of the Periodic Table, taking the general formula MA, where i=12, 13, or 14 and j=15 or 16. For M.sub.12E.sub.16 compounds, M.sub.12 may be cadmium (Cd), zinc (Zn), mercury (Hg), or any combination or alloy thereof, and E.sub.16 may be oxygen (O), sulfur (S), selenium (Se), tellurium (Te), or any combination thereof. For M.sub.13E.sub.15 compounds, M.sub.13 may be boron (B), aluminum (Al), gallium (Ga), indium (In) or any combination or alloy thereof, and E.sub.15 may be nitrogen (N), phosphorous (P), arsenic (AS), antimony (Sb), bismuth (Bi), or any combination thereof. Any such metalloid or semiconductor element(s) or compound(s) may further include an appropriate dopant. Non-limiting examples of metal oxides include silica (SiO.sub.2), alumina (Al.sub.2O.sub.3), titania (TiO.sub.2), zirconia (ZrO.sub.2), germania (GeO.sub.2), stannia (SnO.sub.2), gallia (Ga.sub.2O.sub.3), zinc oxide (ZnO), hafnia (HfO.sub.2), yttria (Y.sub.2O.sub.3), lanthania (La.sub.2O.sub.3), ceria (CeO.sub.2), or any combinations or alloys thereof. Non-limiting examples of a carbon-based intercalants include polymers, block copolymers, or polymer brushes. In a preferred embodiment, the intercalant can be a catalyst (e.g., a single-site catalyst) capable of catalyzing a chemical reaction. A diameter of each intercalant can range from 1 nm to 1000 nm, preferably 1 nm to 50 nm, or more preferably 1 nm to 5 nm. The single-site catalyst can be an intercalant having active sites where a critical reaction step occurs. Due to the affixing of the intercalant between the layers, the active sites on the intercalant can be isolated within the structure of the material.

(31) The intercalants described above may be formed before, during (i.e., in situ), or after any stage of the exfoliation-functionalization/stabilization-restacking (the “formation process,” described in detail below) through reaction of appropriate precursor materials. Non-limiting examples of such reactions include reduction, oxidation, thermal decomposition, or any other chemical or physical reaction. Precursors may be drawn from various classes of compounds and chemical systems, non-limiting examples of which include organometalic compounds, solubilized complexes, metal salts, and solvated ions, or any combination thereof. More specifically, the precursor material can be any appropriate compound containing an atom or atoms of the element or elements of which the intended resulting intercalant is included, and takes the general form MO.sub.yR or MO.sub.yX, where M is a metal of interest (e.g., Pt, Au, Rh, Ru, Re, Os, Ir, Ag, Cu, Fe, Ni, Zn, Mn, Cr, Mo, W, Sn, Si, Al, Ti, Zr, Ge, Ga, Zn, Hf, Y, La, Ce), “y” is fixed by the oxidation state of M, R is an organic ligand, and X is an anion. In some embodiments, 0<y≤3. In other embodiments, y may exceed 3. In yet further embodiments, y=0; in such cases, the chemical formula MO.sub.yR is simplified to MR (“organometallics”) and MO.sub.yX is simplified to MX (“salt”). Non-limiting examples of organic ligands (R) include alkanes, alkenes, alkynes, alcohols, aldehydes, carboxylic acids, phosphines, phosphonates, phosphonic acids, sulfates, sulfides, amines, or the like, or any combination or mixture thereof. Non-limiting examples of anions (X.sup.−) can include halides (e.g., fluoride (F.sup.−), chloride (Cl.sup.−), bromide (Br.sup.−), iodide (I.sup.−)), negatively charged Column 15 elements (nitrogen (e.g., nitrides (N.sup.3−), phosphides (P.sup.3−), arsenide (As.sup.3−), Column 16 based elements (e.g., sulfides (S.sup.2−), selenides (Se.sup.2−), tellurides (Te.sup.2−)), or polyatomic compounds thereof (e.g., sulfates, sulfites, carbonates, carbonites, phosphates, phosphites, acetates, acetylacetonates), or any other appropriate anionic group.

(32) B. Preparation of Intercalated 2D Non-Carbon Mono-Element Multi-Atomic Layered Material

(33) FIGS. 1 through 7 are schematics showing methods of preparing 2D non-carbon mono-element multi-atomic layered material with intercalant(s) and/or precursor(s) thereof intercalated therein along, and the resulting heterogeneous material. The methods of preparation can include one or more steps that can be used in combination to produce the final material. One sequence by which the preparation proceeds is: (1) dispersion; (2) exfoliation and stabilization/functionalization/modification; and (3) aggregation and restacking.

(34) 1. Dispersion

(35) Referring to FIG. 1A, a dispersion (10) containing a parent substrate (11). As shown in FIG. 1A, precursors (12) are included in the dispersion. As shown in FIG. 1B, intercalants (13) can be included in the dispersion and precursors thereof omitted. In yet another embodiment, both intercalants and precursors of the same may be present (not shown). Appropriate media for the dispersion can include any suitable solvent, (e.g., water or any appropriate protic, aprotic, organic, polar, or non-polar solvent). A concentration of the parent substrate in the dispersion can range from 1×10.sup.−5 molar to 5 molar, or 1×10.sup.−4 molar to 4 molar, 1×10.sup.−3 molar to 3 molar, 1×10.sup.−2 molar to 2 molar, or 0.5 to 1 molar.

(36) 2. Exfoliation and Stabilization/Functionalization/Modification

(37) The dispersion can be subjected to a chemical or mechanical process whereby the parent substrate can be exfoliated into single- or few-layered 2D sheets. Non-limiting examples of methods of exfoliation include chemical exfoliation, chemo-mechanical exfoliation, zipper exfoliation, polar or non-polar solvent exfoliation, ionic liquid based exfoliation, or sonication of the liquid composition. By way of example, the parent substrate or parent substrate containing solution can be exfoliated using sonication (i.e., chemo-mechanical exfoliation). The parent substrate can be sonicated for 1 min to 24 hr or 30 min to 12 hr, at a temperature of 20° C. to 200° C., or 25° C. to 100° C., a mixing rate of 0 to 1000 rpm or 50 to 500 rpm, and mixing or sonicating power of 0.1 W to 1000 W. In some aspects, the temperature of the parent substrate can be higher than the temperature of the sonicator bath due to the energy produced from sonication.

(38) Referring to FIG. 2, a dispersion (20) is depicted where single layers (21) and/or multi-layer stacks (22) of the parent substrate are fully exfoliated and are dispersed as discrete free-standing elements in the dispersion solution, which also contains the precursor compound (12) (in one embodiment) and/or intercalants (in other embodiments). The number of layers, n, (23) in the multi-layer exfoliated stack typically range from 2≤n≤10, or 2, 3, 4, 5, 6, 7, 8, 9, or 10.

(39) In certain aspects, after exfoliation, the surface of the free-standing 2D sheets can be stabilized and/or functionalized by the intercalant(s) and/or precursor(s) thereof. Stabilization/functionalization/modification can occur when by physical or chemical reaction between the 2D sheet and the intercalant/precursor compound, a chemical or physical bond between the two is created. Referring to FIG. 3, dispersion (30) is depicted where exfoliated single layers (31) and/or multi-layer stacks (32) of the parent substrate have been functionalized and/or stabilized by the precursors thereof (33) and/or intercalants (34). The result of this process is immobilization of the precursor (33) and/or intercalants (34) on the surface of the 2D sheet (31 and 35, respectively). In a separate embodiment, the intercalant(s) and/or precursor(s) may stabilize and/or functionalize the surface of the parent substrate prior to exfoliation. Without wishing to be bound by theory, such stabilization can facilitate the exfoliation process. The extent to which the surface of the 2D sheets can be covered by the intercalant(s) and/or precursor(s) thereof may be controlled by: (1) the order in which the exfoliation and stabilization/functionalization/modification occurs; and (2) the concentration of the intercalant(s) and/or precursor(s) thereof in the dispersion. FIG. 3 depicts a non-limiting variety of possibilities that serve as non-limiting examples, including: 2D mono-element single-layer 2D non-carbon sheets (31) stabilized/functionalized/modified on a single surface by precursor compounds (without wishing to be bound by theory, such a material can be produced through a process where the surface of the parent substrate can be stabilized/functionalized/modified prior to exfoliation and does not undergo subsequent stabilization/functionalization/modification after exfoliation; although not shown, an analogous material may be produced wherein the number of atomic layers, n, is such that 1<n≤10); 2D mono-element single-layer 2D non-carbon sheets (35) stabilized/functionalized/modified on both the top and bottom surfaces (without wishing to be bound by theory, such a material could be produced through a process where the surface of the parent substrate is stabilized/functionalized/modified prior to exfoliation and undergoes subsequent stabilization/functionalization/modification after exfoliation; alternatively, such a material can be produced through a process wherein exfoliation occurs prior to stabilization/functionalization/modification); 2D mono-element multi-layer 2D non-carbon sheets (32) functionalized on both the top and bottom surfaces (without wishing to be bound by theory, such a material can produced through any of the processes described above with reference to (35); and 2D mono-element single-layer 2D non-carbon sheets (36) stabilized/functionalized/modified on a surface by intercalants (without wishing to be bound by theory, such a material can be produced through any of the processes described above with reference to (31)). In a particular embodiment, although not depicted, architectures analogous to (32) and (35) may be produced where the 2D sheets are stabilized/functionalized/modified with intercalants instead of, or in addition to, precursors (without wishing to be bound by theory, any such materials could be produced through any of the processes described above for (31), (32), or (35)), substituting intercalants for, or incorporating intercalants alongside, precursors thereof. For materials with a plurality of layers, the edges may also be stabilized, functionalized, or modified or a combination thereof (not depicted).

(40) In a particular aspect of the invention where only precursor compounds are included in the dispersion with the parent substrate (i.e., the dispersion does not contain intercalants upon initial preparation), the precursor compounds may be chemically or thermally reduced, such that the metal element of interest (i.e., M, as described above) is reduced to its lowest stable valence or a zero valent state (i.e., M.sup.0). This result can be achieved by introducing a reducing agent or supplying thermal energy to the dispersion. In one embodiment, individual zero-valent atoms of element M (metals) can be produced. In some embodiments, nanoclusters of atoms can be produced. Without wishing to be bound by theory, those atoms can be free to intercalate into the parent substrate to facilitate exfoliation and additional stabilization/functionalization/modification of exfoliated 2D sheets.

(41) In another aspect of the invention where only precursor compounds are included in the dispersion with the parent substrate (i.e., the dispersion does not contain intercalants upon initial preparation), exfoliation and stabilization/functionalization/modification may be accomplished as described above, at which point the dispersion can be subject to a method of reduction (i.e., by introducing a reducing agent to the dispersion or supplying thermal energy) or a chemical reaction sufficient to produce the element or compounds of interest contained within the precursor (e.g., M). Without wishing to be bound by theory, the result of such action can be to produce single atoms, a cluster of atoms, intercalants comprising element M or organic compounds, or a combinations thereof, tethered to the surface of the exfoliated 2D sheets.

(42) 3. Aggregation and Restacking

(43) The final material of the present invention can be produced by allowing the dispersion to settle. In doing so, the stabilized/functionalized/modified exfoliated 2D sheets can aggregate and restack. In one aspect of the technology, this process can form a multi-layered structure with intercalant(s) and/or precursor(s) thereof intercalated between discrete 2D layers or a set of 2D layers. Driving forces for re-stacking or “rapid-restacking” can include the tendency of the parent atoms to form sp.sup.3 hybridized states between the layers. Longer bond lengths with negligible or no pi orbital overlap can drive lattice distortion and thus, necessitate re-stacking. One way to control the restacking rate can be by using pristine powders. Referring to FIG. 4, a schematic of the final material (40) is depicted where intercalants (41) are intercalated between fully exfoliated individual layers of restacked mono-element atomic layers (42). In some instances, only a portion of the intercalant is positioned or intercalates between the layers (See, FIG. 5B). Analogous material systems are contemplated when precursor materials are substituted for the intercalant (41) or when both intercalants and precursors thereof are co-intercalated between individual layers of restacked mono-element atomic layers (42). As shown, the intercalants can be varied in size, however, it should be understood that the size and shape of the intercalant or precursor material can be any size or shape as long as a portion of the intercalant or precursor material can intercalate between the exfoliated layers.

(44) In another aspect of the present invention, referring to FIGS. 5A and 5B, the restacking process described above can include exfoliated 2D sheets with a plurality of atomic layers, n, (with 1<n≤10), in which case, the final material (50) contains intercalants (41) intercalated between: (a) individual layers of restacked mono-element atomic layers (42); and/or (b) between individual layers that are separated by n layers (52) wherein no precursor compound is intercalated. In a preferred aspect, no region of the final material contains more than 20 consecutive monoatomic layers wherein no precursor compound is intercalated. As shown in FIG. 5B, the layers are partially exfoliated and a portion of the intercalant (41) is affixed between the two atomic layers (42) while other layers have the entire intercalant (41) immobilized between the two atomic layers (42). Analogous material systems include precursor compounds substituted for the intercalants (41) and when both intercalants and precursors thereof are co-intercalated between individual layers of restacked mono-element atomic layers (42). Also, it should be understood that the separated layers (52) are between layers are partially or not exfoliated layers (e.g., layers depicted in FIG. 5B).

(45) In yet another aspect, referring to FIG. 6, exfoliated mono-element 2D sheets stabilized/functionalized/modified with intercalants on both the top and bottom surfaces (See, for example sheet (35) of FIG. 3) can restack forming a final material (60) having a intercalants (12) intercalated between individual layers of restacked mono-element atomic layers (42) and intercalant type material (61) on the outer surface of the layers. In an analogous system, both intercalants and precursors thereof can be co-intercalated between individual layers of restacked mono-element atomic layers (42). Other systems analogous to each of those just described where intercalated bilayers (comprising intercalants(s) and/or precursor(s) thereof) are separated by individual layers, n, wherein no precursor compound is intercalated. In a preferred aspect, no region of the final material contains more than 20 consecutive monoatomic layers wherein no intercalant or precursor compound is intercalated.

(46) 4. Exfoliation, Functionalization and Restacking

(47) In some embodiments, functionalized powders and/or functionalized sites can be used to inhibit restacking and/or reduce the rate of restacking when single layers cannot be isolated using conventional exfoliation methods (e.g. silicene). By way of example, a parent substrate (e.g., functionalized silicene architectures) can be modified with another compound or metal (e.g., Ag, or intercalants) to result in intercalated multi-atomic layered material. Referring to FIG. 7A, a schematic of a one-pot exfoliation, functionalization, and restacking is depicted. In method 70, the parent substrate (e.g. CaSi.sub.2) (71) can be chemically-exfoliated in a liquid phase (72) into single layers (73) using the methods as described throughout the specification and the Example Section. During this process, intercalants (74) (e.g., a silver salt) and reducing agent (not shown) can be introduced into the solution. After the nucleation of intercalants (i.e. Ag), the exfoliation process can be stopped and 2D layers of parent material (e.g., silicene) can be allowed to re-aggregate or re-stack to form exfoliated multi-atomic layered non-carbon mono-element stack (75) (e.g., a silver-silicene). In some embodiments, the size of nucleated intercalant (e.g., Ag) can be sub-nanometer and then the re-stacking process can be assisted by formation of sp.sup.3 hybridization or inter-layer bonding in the 2D layer (e.g., silicene). In other embodiments, the nucleated intercalant can be sub-nanometer to 5 nm, and then the nucleated intercalant itself can provide sites for satisfying the sp.sup.3 hybridization need of the re-stacked 2D layer. The liquid can be removed from the exfoliated multi-atomic layered non-carbon mono-element stack (75), and the stack (75) can be exposed to an oxygen source to convert the stack into a 2D oxide support (e.g., silicene oxide). Oxidation of the 2D support can result in a unique interaction with intercalant, impart high thermal stability, and enhanced lifetime of the 2D support. The interaction between the 2D layer and the intercalant can result in a robust confinement for the intercalant (e.g., Ag clusters) and at the same time provide atomically-flat surfaces between the stacked layers, which can be beneficial for specular transport of species (e.g., diffusion of the reactants into the layers and products out of the layers) during a catalytic reaction. When a catalytic metal is used, the process can result in a catalyst for high conversion and selectivity for a specific reaction. The specific catalytic reaction can be dependent on the material choice of clusters and 2D layers.

(48) Referring to FIG. 7B, functionalization of the single layers followed by intercalation of intercalants is depicted. As described in FIG. 7A, the parent material 71 can be exfoliated into single layer. Functionalizing agent (77) can be added to the solution and the single layers (73) can be reacted with a functionalizing agent to create functionalized layers (78). By way of example, exfoliated silicene layers can undergo hydrosilylation, aminization, or acylation (e.g., phenylation) reactions to produce silicate hydrocarbons, silicene amines (Si—Si—N bond), and phenylated silicene (Si—Si-phenyl). Intercalants (74) can be added to the solution and intercalated between the layers and/or functional groups during restacking of the layers to form intercalated multi-atomic layered material (78). Although FIGS. 7A and 7B are shown in a stepwise manner, the process can be performed in a single step by adding the intercalants and the functionalization agent to the solution during the same step.

(49) In some instances, the above-mentioned intercalants or precursors thereof are affixed between the first and second atomic layers and can fill 1% to 80%, preferably 30% to 60%, of the volume between each 2D layer once restacked. A total weight percentage of the intercalants or precursor thereof can range from 10 wt. % to 90 wt. %.

(50) In some embodiments, the material described throughout the specification is appropriate and ready for use when prepared as described above. In other embodiments, the material of the present invention may further be loaded onto a support material or carrier (e.g., for use in catalysis). Such a support material or a carrier to which the catalytic material of the present invention is affixed can be porous and have a high surface area. In some embodiments, the support includes a non-carbon oxide, alpha, beta or theta alumina (Al.sub.2O.sub.3), activated Al.sub.2O.sub.3, silica (SiO.sub.2), titania (TiO.sub.2), magnesia (MgO), calcium oxide (CaO), strontia (SrO), zirconia (ZrO.sub.2), zinc oxide (ZnO), lithium aluminum oxide (LiAlO.sub.2), magnesium aluminum oxide (MgAlO.sub.4), manganese oxides (MnO, MnO.sub.2, Mn.sub.2O.sub.4), lanthanum oxide (La.sub.2O.sub.3), activated carbon, silica gel, zeolites, activated clays, silicon carbide (SiC), diatomaceous earth, magnesia, aluminosilicate, calcium aluminate, carbon nanotubes (CNT), or boron nitride nanotubes (BNNT), or combinations thereof.

(51) C. Applications of Intercalated 2D Non-Carbon Mono-Element Multi-Atomic Layered Material

(52) 1. Catalysts for Chemical Reactions

(53) In a particular instance, the materials of the present invention can be used as catalytic material suitable for use in any number of various chemical reactions. A non-exhaustive list of potentially suitable reactions which may be catalyzed by the materials of the present invention include a hydrocarbon cracking reaction, a hydrogenation of hydrocarbon reaction, a dehydrogenation of hydrocarbon reaction, an environmental remediation reaction, an epoxidation reaction, an automobile catalytic reaction, a solar energy harvesting reaction, a petrochemical conversion reaction, an oxidative coupling of methane reaction, a carbon dioxide to carbon monoxide conversion reaction, a methane to methanol reaction, a methanol to ethylene reaction, a water splitting, a hydrogen gas and oxygen to hydrogen peroxide reaction, a benzene to phenol reaction, an aryl to amine reaction, a benzene with NH.sub.3 to Bz-NH.sub.2 reaction, etc. By way of example, a 2D silicene oxide with embedded clusters of Pt/Sn can be used for a dehydrogenation reaction. A 2D silicene oxide or germicene oxide with embedded Ag clusters can be used for an epoxidation reaction. A 2D silicene oxide with embedded CrO.sub.x clusters can be used for a dehydrogenation reaction. A 2D silicene oxide with embedded Cu clusters can be used for CO.sub.2 conversion. Similarly, alloyed nanoparticles or clusters, precious metal group systems, or other 2D material sheets or quantum dots can be embedded or positioned between the 2D layers for desired function.

(54) Referring to FIG. 8, a schematic of a system (80) for use in a chemical reaction is depicted. System (80) may include a continuous flow reactor (81) and the multi-atomic layered material of the present invention (82). A reactant stream that includes chemical reactants can enter the continuous flow reactor (81) via a feed inlet (83). In one embodiment, the reactants can be provided to the continuous flow reactor (81) such that the reactants are heated to a temperature between ambient (i.e., room temperature) and the reaction temperature prior to contacting the catalytic material (82). In another embodiment, the catalytic material (82) and the reactant feed are each heated to the approximately the same temperature. In some instances, the catalytic material (82) may be layered in the continuous flow reactor (81). In other instances, the catalytic material may be fed to the reactor while in contact with the reactant mixture in a fluidized bed configuration. In such an embodiment, the catalytic material may be pre-mixed with the reactant stream prior to entering the reactor (81) or it may be introduced through a second inlet stream (84) and brought into contact with the reactant feed immediately thereafter. Contact of the reactant mixture with the catalytic material (82) can produce a product stream. The product stream can exit the continuous flow reactor (81) via product outlet (85). The resulting product stream can be further processed and separated from any by-products using a variety of known gas/liquid separation techniques such as distillation, absorption, membranes, etc., to produce a purified product stream. In some instances, the products can then be used in additional downstream reaction schemes to create additional products.

(55) 2. Additional Applications

(56) The intercalated 2D non-carbon mono-element multi-atomic layered materials described above (with or without support structures) can also be included in articles of manufacture, made into sheets, films, or incorporated into membranes. The sheet or film can have a thickness of 10 nm to 500 μm. The article of manufacture can be an energy storage/conversion/transport device, an actuator, a piezoelectric device, a sensor, a smart textile, a flexible device, an electronic device, an optical device, an optoelectronic device, an electro-optical device, a plasmonic device, a delivery device, a polymer nanocomposite, an actuating device, a MEMS/NEMS device, a logic device, a filtration/separation device, a capturing device, an electrochemical device, a display device etc. Other article of manufacture include curved surfaces, flexible surfaces, deformable surfaces, etc. Non-limiting examples of such articles of manufacture include virtual reality devices, augmented reality devices, fixtures that require flexibility such as adjustable mounted wireless headsets and/or ear buds, communication helmets with curvatures, medical batches, flexible identification cards, flexible sporting goods, packaging materials and/or applications where the presence of a bendable energy source simplifies final product design, engineering, and/or mass production

EXAMPLES

(57) The present invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes only, and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters which can be changed or modified to yield essentially the same results.

Materials and Instrumentation

(58) Calcium silicide (CaSi.sub.2) and potassium hydroxide (KOH) were obtained from Fisher Chemical™ (Fisher Scientific International, Inc., U.S.A.). Chloroauric acid (HAuCl.sub.4) and sodium borohydride (NaBH.sub.4) were obtained from Sigma-Aldrich® (U.S.A.). Deionized water (DI) was obtained from a Thermo Scientific™ Barnstead™ DI water system-Smart2Pure™ (Fisher Scientific International, Inc., U.S.A.).

(59) Inductively coupled plasma (ICP) data was obtained using a Optima™ 8300 (Perkin Elmer, U.S.A.). X-ray diffraction (XRD) spectra was obtained using a Rigaku SmartLab X-Ray Diffractometer (Rigaku Americas Corporation, U.S.A.). Ramon spectra were obtained using a Renishaw inVia™ Raman Microscope (Renishaw, U.S.A.). Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) data was obtained using a JSM-7800F (JEOL, U.S.A.). Transmission electron microscopy (TEM) data was obtained using a JEM-2010F (JEOL, U.S.A.).

Example 1

Method of Making a Au Intercalated Silicene Multi-Atomic Layered Material of the Present Invention

(60) In a controlled atmosphere (glove box), CaSi.sub.2 (1×10.sup.−3M) was added to KOH (20 ml, 0.01 M) solution and stirred for 1-3 hours. To a portion (2 mL) of the CaSi.sub.2/KOH solution, isopropyl/hydrochloric acid (0.6 gm) was added and stirred from 5 to 60 min. During the addition and agitation, evolution of gas was observed. The gas was assumed to be H.sub.2. The acidified solution was sonicated for 15-30 min, and then HAuCl.sub.4 (2 ml of a 3-4 mg HAuCl.sub.4 in 40 ml water solution) was added under sonication. After 5-10 min of additional sonication, NaBH.sub.4 (1 ml of 4.5 mg NaBH.sub.4 in 2 ml water solution) was added, sonication was continued for 5-15 min, and then the solution was allowed to stand for >24 hrs for re-stacking of layered material to occur. The resulting solution had a top clear layer and precipitate. Characterization was conducted on the top clear solution layer and the precipitate. From the characterization, it was determined to be a mixture of gold intercalated silicene, silicon, and starting material.

Example 2

Characterization of Au Intercalated Silicene Multi-Atomic Layered Material of the Present Invention

(61) Characterization of the reaction intermediates and products was performed using SEM, TEM, ICP, EDS, XRD and Raman methodologies.

(62) After KOH Addition.

(63) After KOH addition, SEM analysis was performed on the CaSi.sub.2. FIG. 9 is a SEM image of the bulk CaSi.sub.2 after KOH treatment. From the SEM, it was determined that the CaSi.sub.2 was not separated (i.e., in bulk form).

(64) Immediately after Sonication has Ended.

(65) The solution was sampled immediately after ending the sonication. FIG. 10 is a SEM image of the precipitated material immediately after ending the sonication. Comparing FIG. 10 to FIG. 9, it was determined that the bulk CaSi.sub.2 had separated and started to restack as silicene (2-D silicon) with gold intercalated in the layers as layers are present in FIG. 10. Gold intercalates are the light colored spots (as indicated by the arrow).

(66) 1 Day after Sonication.

(67) FIG. 11 is a SEM image of the precipitate twenty-four hours after sonication of CaSi.sub.2. From the image, it was determined that gold nanoparticles are intercalated (arrows) in the restacked silicene material.

(68) 1. ICP Analysis of Clear Layer and Au/CaSi.sub.2 Precipitate.

(69) Both the top clear liquid layer and the precipitate were analyzed by ICP for Si, Ca, and Au. Table 1 lists the ppm of Si, Ca, and Au in each layer. Comparing the data from the top layer to the precipitate layer, it was determined that the ratio of silicene or silicon nanostructures to calcium was about 10 times higher in the solution than in the precipitate. Without wishing to be bound by theory, it is believed that the heavier silicide (silicon) material precipitated while the top clear layer included more 2D monoelement architectures (silicene material). Although the top solution appeared clear, from the data it was determined that it included re-stacked monoelements with intercalants.

(70) TABLE-US-00001 TABLE 1 Si ppm Ca ppm Au ppm Top layer 5.6 ± 0.2 13.8 ± 0.4 0.003 Precipitate 3.4 ± 0.2 104.7 ± 2   2.1 ± 0.03

(71) 2. EDS Analysis

(72) FIG. 12 is a SEM image of the precipitate twenty-four hours after sonication of CaSi.sub.2 used for EDS analysis. EDS analysis was used on the flake shown in the SEM image of FIG. 12, with the area outlined by the square being evaluated. Table 2 lists the weight percent and atomic percent of the elements present in the flake. From the data, it was determined that the flake had a high silicon content as compared to Ca content, which indicated that the re-stacked flake was primarily silicon (Si), however, re-stacked silicene with intercalated Au were also detected. The Au signal was low because most of the Au was intercalated within the re-stacked layers.

(73) TABLE-US-00002 TABLE 2 Element Weight % Atomic % O K 10.87 18.70 Si K 77.23 75.70 Ca K 2.10 1.44 Cu L 9.50 4.12 Au M 0.29 0.04 Total 100.00 100.00

(74) EDS of the control CaSi.sub.2 starting material (non-exfoliated) was performed. FIG. 13 is a SEM image of the CaSi.sub.2 material after KOH treatment with the material inside the box being analyzed. Table 3 lists the weight percentage and atomic percentage of elements detected. From the data, it was determined that the Control CaSi.sub.2 had about twice the Si content as compared with Ca (stoichiometrically, Ca:Si=1:2). While the sonicated sample showed exfoliated and re-stacked silicene with significantly high amount of Si in the system. Cu, Al, and O were present due to the base grid substrate on which the flakes were dispersed. K was present due to unwashed KOH.

(75) TABLE-US-00003 TABLE 3 Element Weight % Atomic % C K 10.28 18.87 O K 27.56 37.99 Al K 0.36 0.29 Si K 38.44 30.19 K K 0.10 0.05 Ca K 22.30 12.27 Cu L 0.97 0.34 Totals 100.00 100

(76) 3. TEM Analysis

(77) FIG. 14 is a TEM image of the precipitate twenty-four hours after sonication of CaSi.sub.2. From the TEM image, it was determined that silicene layers with intercalated gold nanoparticles were present. The inter-layer spacing of the layers was 0.25 to 0.3 nm, which is consistent for silicene layers (strained or unstrained). The presence of 2 to 3 layers or multi-layers was observed.

(78) 4. XRD Analysis

(79) FIG. 15 depicts an XRD pattern of the precipitate twenty-four hours after sonication of CaSi.sub.2. Peaks at 29.18, 44.22 and 64.94 are attributed to gold (111, 200, 220 phases). The peak at 28.46 was attributed to Si. The rest of the peaks are attributable to calcium silicide. A trace amount of SiO.sub.2 was present.

(80) 5. Raman Analysis

(81) FIG. 16 is a Raman spectrum of the sonicated precipitate. FIG. 17 is a Raman spectrum of the CaSi.sub.2 starting material after KOH treatment. Major peaks at 130.8, 208, 347.6, 385.9, 415.3, 519.3 cm.sup.−1 were observed. The peak at 519.3 was attributed to multi-layer silicene as multi-layer silicene is known to have a Raman shift between 516 and 525. The shoulder between 520 cm.sup.−1 and 570 cm.sup.−1 was attributed to the gold nanoparticles. The starting CaSi.sub.2 material had peaks at 129.1, 198.8, 334.3, 381.1, 407.3, 511.488 cm.sup.−1. From the data, it was determined that some starting CaSi.sub.2 material was present in the precipitate. However, a majority of the precipitate was the restacked gold intercalated silicene material.

(82) From analysis of the data and the images, it was determined that a multi-layered material having a first 2D non-carbon mono-element atomic layer, a second 2D non-carbon mono-element atomic layer, and intercalants positioned between the first and second atomic layer was made using the method of the invention.