Borophene tubes, methods of making same, and uses thereof

Abstract

Hollow tubes or fibers, methods of making hollow tubes or fibers, and uses thereof. In various examples, a hollow tube or fiber (e.g., a borophene tube or fiber or the like) comprises a single or plurality of single layers of boron atoms, where each single layer is crystalline, comprises χ3, β 12, δ6, α, Pmmn, Pmmm, α-icosohedral, or β-icosohedral phase borophene, comprises hexagonal pyramidal and / or icosahedral unit(s) or group(s), or any combination thereof. In various examples, a method of making a hollow tube or fiber comprises exfoliation (e.g., by mechanically mixing and / or agitation) of a boron precursor, such as, for example, a boron powder or crystal, under pressure. Hollow tubes or fibers can be used in various applications and devices, such as, for example, energy or gas storage, sensing, field emission, thermal conductivity, molecular electronic, structural, fiber / fabric, biomedical, electronic, or molecular electronic, filtration, or catalysis, or the like applications or devices, or in materials, such as, for example, conducing adhesives, or thermal or reinforcing materials.

Description

Attorney Docket No.: UBRF-106-B-WOBOROPHENE TUBES, METHODS OF MAKING SAME, AND USES THEREOFCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 707,591, filed October 15, 2024 and entitled “Borophene Tubes, Methods of Making Same, and Uses Thereof.” The entire contents of the above-identified priority application are hereby fully incorporated herein by reference in their entirety.BACKGROUND

[0002] Borophene tubes have been predicted to be useful in energy storage / generation, with potential applications in electronic chips, spintronic chips and in optoelectronics, and in hydrogen and halogen storage. They have been predicted to be a suitable material for a host of sensing applications such as for gas, light, strain and explosive materials, as well as for disease diagnosis. This broad spectrum of applications mirrors the broad range of applications of their carbon analog - carbon nanotubes.

[0003] Borophene is a new 2D material which was first experimentally discovered to form under atomic layer deposition conditions. Within a short time, it was obtained via molecular beam epitaxy. However, it was postulated that because boron is not a van der Waals material, that it cannot therefore be exfoliated, and this opinion largely prevailed. Such belief stems from the fact that boron tends to form unusual two-center- three-electron bonds, which results in atomic cluster formation. Such 3D clusters would not appear to allow it to form atomic sheets. This misperception acted as roadblock to development of this important material. Further, boron was expected to be chemically very reactive towards oxygen under ambient processing conditions and therefore attaining atomic borophene metallic sheets under ambient conditions was presumed infeasible.SUMMARY OF THE DISCLOSURE

[0004] The present disclosure describes, inter alia, borophene tubes and compositions and methods of making same. The present disclosure also provides uses of borophene tubes and compositions.

[0005] In an aspect, the present disclosure provides hollow tubes, hollow fibers, and the like. In various examples, hollow tube is a borophene tube or the like or a hollow fiber is a borophene fiber or the like. In various examples, a hollow tube, a hollow fiber, or the like (such as, forexample, a borophene tube, a borophene fiber, or the like) is produced by a method of the present disclosure. In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) is configured for a use described herein. In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) comprises, consists essentially of, or consists of a single layer comprising boron atoms or two or more layers, where each layer independently comprises boron atoms. In various examples, the single layer or each of the two more layers is borophene or a borophene layer or a 2D layer (e.g., atomically thin or the like) of boron atoms. In various examples, each of the boron atoms is independently covalently bonded to at least two other boron atoms (e.g., 2, 3, 4, or 5 other boron atoms). In various examples, at least a portion, substantially all, or all of the boron atoms of the borophene tube is / are oxidized. In various examples, the hollow tube (or the single layer or the two or more layers independently) comprises, consists essentially of, or consists of (or is) one or more or a plurality of hexagonal pyramidal units or groups (such as. for example, dovetailed hexagonal pyramidal units or groups or the like), icosahedral units or groups, or a structural analog or analogs thereof, or the like, or any combination thereof, where each hexagonal pyramidal units or group (such as, for example, a dovetailed hexagonal pyramidal unit or group or the like), icosahedral unit or group, or the structural analog or analogs thereof, or the like, or the combination thereof comprises boron atoms (e.g., where each of the boron atoms is independently covalently bonded to at least two other boron atoms (e.g., 2, 3, 4, or 5 other boron atoms)). In various examples, one or more or all of the single layer or each of the two or more layers is / are independently at least partially, substantially, or completely crystalline. In various examples, at least a portion, substantially all, or all of the single layer or each of the two or more layers independently is / are or comprises xi phase borophene, / 3i 2 phase borophene, be phase borophene, a phase borophene, Pmmn phase borophene, Pmmm phase borophene, a-icosohedral phase borophene, P-icosohedral phase borophene, a structural analog thereof, or the like, or any combination thereof. In various examples, the hollow tube, the hollow fiber, or the like (such as, for example, the borophene tube, the borophene fiber, or the like) (or the single layer or each of the two or more layers) is / are independently metallic, comprise a metallic electronic structure, exhibit metallic or semi-metallic behavior, or the like. In various example, the hollow tube, the hollow fiber, or the like (such as, for example, the borophene tube, the borophene fiber, or the like) comprises (or has) a length orthe like of about 50 nm about 5 pm, including all 0.1 nm values and ranges therebetween and / or a linear, cross-sectional dimension or the like of about 1 nm to about 2 pm, including all 0.1 nm values and ranges therebetween. In various examples, the hollow tube, the hollow fiber, or the like (such as, for example, the borophene tube, the borophene fiber, or the like) is free-standing or the like.

[0006] In an aspect, the present disclosure provides compositions comprising hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like), or any combination thereof of the present disclosure. In various examples, a composition is produced by a method and / or used in a method of the present disclosure. In various examples, a composition is suitable of configured for or is used in a material or a device of the present disclosure. In various examples, a composition comprises a plurality of hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like), or any combination thereof. In various examples, at least a portion, substantially all, or all of the hollow tubes, the hollow fibers, or the like (such as. for example, the borophene tubes, the borophene fibers, or the like), or the combination thereof in the composition are substantially the same or the same or two or more or all of the hollow tubes, the hollow fibers, or the like (such as, for example, the borophene tubes, the borophene fibers, or the like) or the combination thereof in the composition are different. In various examples, the composition comprises the hollow tubes, the hollow fibers, or the like (such as, for example, the borophene tubes, the borophene fibers, or the like), or the combination thereof independently comprise (or at least 80% or more comprise (or have)) a length or the like and / or the hollow tubes, the hollow fibers, or the like (such as, for example, the borophene tubes, the borophene fibers, or the like), or the combination thereof comprise (or have) an average length or the like of about 50 nm to about 5 pm, including all 0.1 nm values and ranges therebetween. In various examples, the composition comprises the hollow tubes, the hollow fibers, or the like (such as. for example, the borophene tubes, the borophene fibers, or the like), or the combination thereof independently comprise (or have) (or at least 80% or more comprise (or have)) a linear, cross-sectional dimension or the like or the hollow tubes, the hollow fibers, or the like (such as, for example, the borophene tubes, the borophene fibers, or the like), or the combination thereof comprise (or have) an average linear, cross-sectional dimension or the like of about 1 nm to about 2 pm, including all 0.1 nm values and ranges therebetween. In various examples, at least a portion, substantially all, or all of the boron atomsof one or more, substantially all, or all of the hollow tubes, the hollow fibers, or the like (such as, for example, the borophene tubes, the borophene fibers, or the like), or the combination thereof is / are oxidized.

[0007] In an aspect, the present disclosure provides methods of making hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like), or any combination thereof. In various examples, a method produces a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof and / or a composition of the present disclosure. In various examples, a method of making a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof comprises, consists essentially of, or consists of: a mechanically mixing, agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like a composition (such as, for example, a reaction mixture or the like) comprising: one or more boron precursor(s): and one or more solvent(s), under pressure (e.g., elevated pressure, which may be greater than ambient pressure) (which may be autogenous pressure or the like). In various examples, mechanically mixing, agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like, or any combination thereof results in exfoliation of at least a portion of the boron precursor(s). In various examples, the solvent(s) each independently exhibit(s) one or more or all of: a vapor pressure of about 0.05 bar to about 1.2 bar (e.g., at room temperature or the like), including all 0.01 bar values and ranges therebetween (e.g.. about 0.05 bar to about 0.7 bar (e.g., at room temperature or the like), about 0.5 bar to about 0.7 bar (e.g., at room temperature or the like)), about 0.5 bar to about 1.2 bar (e.g., at room temperature or the like), about 0.2 bar to about 0.5 bar (e.g., at room temperature or the like), or about 0.25 bar (e.g.. at room temperature or the like): a boiling point of about 40 °C to about 75 °C, including all 0.1 °C values and ranges therebetween (e.g., about 50 °C to about 60 °C); a boiling point vapor pressure (or a critical pressure or the like) of about 46 bar to about 46.9 bar, including all 0.1 bar values and ranges therebetween (e.g., about 46.4 bar to about 46.9 bar); miscibility in benzene, diethyl ether, methanol, chloroform, ethanol, or the like, or any combination thereof: or a density of about 0.784 (e.g., 0.7845) g / cm\ Non-limiting examples of solvents include ketones (e.g., acetone, which may be ACS grade acetone or thelike, structural analogs thereof, and the like), structural analogs thereof, and the like, and any combination thereof. In various examples, the mechanically mixing, the agitating, or the like is micromechanically mixing or agitating, micromechanical exfoliating, or the like, or any combination thereof and / or the agitating is sonochemical agitating or the like. In various examples, the mechanically mixing, the agitating (e.g., sonochemically exfoliating, ultrasonically agitating, intercalation-mediated exfoliating, or the like, or any combination thereof), or the like, or any combination thereof results in exfoliation of at least a portion of the boron precursor(s) and production of at least one intermediate (such as, for example, borophene sheet(s) or the like). In various examples, the method further comprises oxidizing at least a portion, substantially all, or all of a product (e.g., borophene tube(s) (such as, for example, hollow fiber(s), hollow tube(s), or the like) or a composition). In various examples, a method further comprises isolation of a product (e.g., borophene tube(s), such as, for example, hollow fiber(s), hollow tube(s), or the like, or a composition).

[0008] In an aspect, the present disclosure provides uses of a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof or a composition or compositions of the present disclosure. The hollow tube or tubes, the hollow fiber or fibers, or the like (such as, for example, the borophene tube or tubes, the borophene fiber or fibers, or the like), or the combination thereof and / or the composition or the compositions can be used in applications such as, for example, energy storage and / or generation, in optoelectronic applications, in gas storage, in sensing applications, in field emission applications, in thermal conductivity applications, in molecular electronic applications, in structural applications, in fiber / fabric applications, in biomedical applications, in electronic applications, in molecular electronic applications, in filtration applications, in catalysis applications, as conductive adhesives, as thermal materials, and the like. In various examples, a material (such as, for example, a conductive adhesive, a thermal material, a sensor material, a reinforcing material, or the like, or any combination thereof) comprises the hollow tube or tubes, the hollow fiber or fibers, or the like (such as, for example, the borophene tube or tubes, the borophene fiber or fibers, or the like), or the combination thereof and / or the composition or compositions.

[0009] In an aspect, the present disclosure provides devices. In various examples, a device comprises a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, aborophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof or a composition or compositions of the present disclosure. In various examples, the device is a sensor, an actuator, a detector, or the like or the device comprises a sensor, an actuator, a detector, or the like, or any combination thereof. In various examples, the device is an energy storage and / or generation device, an optoelectronic device, a gas storage device, a sensing device, a field emission device, a thermal conductivity device, a molecular electronic device, a filtration device, or the like, or any combination thereof.

[0010] In various examples, methods of the present disclosure provide a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof, or a composition is / are generated by sonochemical exfoliation, an approach that is not only low-cost but also scalable for industrial production. It is considered this development effectively opens the door to a new class of materials, with potential to drive innovation in important areas described herein (such as, for example, sensor technology, high-capacity batteries, spintronic computing, and the like).BRIEF DESCRIPTION OF THE FIGURES

[0011] For a fuller understanding of the nature and objects of the disclosure, reference should be made to the following detailed description taken in conjunction with the accompanying figures.

[0012] FIG. 1 shows (a)-(c) optical images of hollow tubes on Si / SiO2 substrates from a hollow tube synthesis showing diameters of a few microns to tens of microns.

[0013] FIG. 2 shows optical images (drop cast solution without any treatment / filtration) of hollow tubes on Si / SiO2 substrates from another borophene synthesis (using the same reaction parameters as the synthesis of the borophene tubes shown in FIG. 1 A) showing hollow tubes with diameters of a few microns to tens of microns demonstrating repeatability of the synthesis.

[0014] FIG. 3 shows bright field TEM image of a hollow tube.

[0015] FIG. 4 shows intensity profile from different regions of a hollow tube.

[0016] FIG. 5 shows fast Fourier transform (bottom) pattern of a hollow tube image (top).

[0017] FIG. 6 shows local fast Fourier transform pattern of a hollow tube image.

[0018] FIG. 7 shows Electron Energy Loss Spectroscopy (EELS) of a hollow tube.

[0019] FIG. 8 shows High-Resolution Transmission Electron Microscopy (HRTEM) image of a hollow tube.[0020| FIG. 9 shows High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM) characterization and corresponding Energy Dispersive X-ray (EDX) spectroscopy quantification of a hollow tube.

[0021] FIG. 10 shows HAADF-STEM and EELS characterization and corresponding Energy Dispersive X-ray (EDX) spectroscopy quantification of a hollow tube.

[0022] FIG. 11 shows beta- 12 with protrusion borophene phases.

[0023] FIG. 12 shows SEM images of borophene sheets (a)-(d) formed when boron powder was not kept under the pressurized condition during synthesis.

[0024] FIG. 13 shows SEM images of borophene sheets formed from boron powder (commercially available - ottokemi.com, <50 micro-meter, 99% Code- B 0063) when boron powder was not kept under pressurized condition during synthesis.

[0025] FIG. 14 shows laser on / off cycles for red (650 nm), green (532 nm), and blue (405 nm) wavelength for (a) borophene sheet and (b) borophene tube, (c) Shows a bar graph of their response %.

[0026] FIG. 15 shows cyclic voltammetry (CV) comparison of unmodified and modified electrodes (BSs / PPy@ITO and HTs / PPy@ITO) recorded in blank electrolyte and in 0.1 M KC1 containing 50 pM caffeine.

[0027] FIG. 16 shows a bar graph comparing the oxidation peak current densities of BSs / PPy@ITO and HTs / PPy@ITO electrodes.DETAILED DESCRIPTION OF THE DISCLOSURE

[0028] Although subject matter of the present disclosure is described in terms of certain embodiments and examples, other embodiments and examples, including embodiments and examples that do not provide all of the benefits and features set forth herein, are also within the scope of this disclosure. For example, various structural, logical, and process step changes may be made without departing from the scope of the disclosure.

[0029] As used herein, unless otherwise indicated, “about”, “substantially”, or “the like”, when used in connection with a measurable variable (such as, for example, a parameter, an amount, a temporal duration, or the like) or a list of alternatives, is meant to encompass variations of and from the specified value including, but not limited to, those within experimental error (which can be determined by, e.g., a given data set, an art accepted standard, etc. and / or with, e.g., a given confidence interval (e.g., 90%, 95%, or more confidence interval from themean), such as, for example, variations of + / -10% or less, +1-5% or less, + / -1 % or less, and + / - 0.1% or less of and from the specified value), insofar such variations in a variable and / or variations in the alternatives are appropriate to perform in the instant disclosure. As used herein, the term “about” may mean that the amount or value in question is the exact value or a value that provides equivalent results or effects as recited in the claims or taught herein. That is, it is understood that amounts, sizes, compositions, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error, or the like, or other factors known to those of skill in the art such that equivalent results or effects are obtained. In general, an amount, size, composition, parameter, or other quantity or characteristic, or alternative is “about” or “the like,” whether or not expressly stated to be such. It is understood that where “about,” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0030] Ranges of values are disclosed herein. The ranges set out a lower limit value and an upper limit value. Unless otherwise stated, the ranges include the lower limit value, the upper limit value, and all values between the lower limit value and the upper limit value, including, but not limited to, all values to the magnitude of the smallest value (either the lower limit value or the upper limit value) of a range. It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a numerical range of “0.1% to 5%” should be interpreted to include not only the explicitly recited values of 0.1% to 5%, but also, unless otherwise stated, include individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.5% to 1.1%; 0.5% to 2.4%; 0.5% to 3.2%, and 0.5% to 4.4%, and other possible sub-ranges) within the indicated range. It is also understood (as presented above) that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. Similarly, when values are expressed as approximations, by useof the antecedent “about,” it will be understood that the particular value forms a further disclosure. For example, if the value “about 10” is disclosed, then “10” is also disclosed.

[0001] As used herein, unless otherwise stated, the term “structural analog” refers to any hollow tube, hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (such as, for example, an oxidized hollow tube, an oxidized hollow fiber, or the like (such as, for example, an oxidized borophene tube, an oxidized borophene fiber, or the like), solvent, or the like, or any portion thereof (such as, for example, one or more group(s) thereof or the like) or group if one atom or group of atoms, functional group or functional groups, or substructure or substructures is / are replaced with another atom or group of atoms, functional group or functional groups, substructure or substructures, or the like. In various examples, the term “structural analog” refers to any group that is derived from an original hollow tube, hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (such as, for example, an oxidized hollow tube, an oxidized hollow fiber, or the like (such as, for example, an oxidized borophene tube, an oxidized borophene fiber, or the like), solvent, or a portion thereof (such as, for example, one or more group(s) thereof or the like) or the like by a chemical reaction, where the original hollow tube, hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (such as, for example, an oxidized hollow tube, an oxidized hollow fiber, or the like (such as, for example, an oxidized borophene tube, an oxidized borophene fiber, or the like), solvent, or the like or the portion thereof (such as, for example, one or more group(s) thereof or the like) or the like is modified or partially substituted such that at least one structural feature of the original hollow tube, hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (such as, for example, an oxidized hollow tube, an oxidized hollow fiber, or the like (such as, for example, an oxidized borophene tube, an oxidized borophene fiber, or the like), solvent, or the like or the portion thereof (such as, for example, one or more group(s) thereof or the like) or the like is retained in the structural analog.

[0002] As used herein, unless otherwise stated, the term “group” refers to a chemical entity that is monovalent (i.e., has one terminus that can be (is) covalently bonded to other chemical species), divalent, or polyvalent (i.e., has two or more termini that can be (are) covalently bonded to other chemical species). The term “group” also includes radicals (e.g., monovalent radicals and multivalent radicals, such as, for example, divalent radicals, trivalent radicals, and the like).Illustrative examples of groups include:the like.

[0031] The present disclosure describes, inter alia, hollow tubes, hollow fibers, or the like and compositions thereof and methods of making same. The present disclosure also provides uses of hollow tubes, hollow fibers, or the like and compositions thereof.

[0032] In an aspect, the present disclosure provides hollow tubes, hollow fibers, and the like. In various examples, hollow tube is a borophene tube or the like or a hollow fiber is a borophene fiber or the like. In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) is produced by a method of the present disclosure. In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) is configured for a use described herein. Nonlimiting examples of borophene tubes are disclosed herein.

[0033] In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like), which may be a single- wall hollow tube or fiber (or single-wall boron tube or fiber), such as, for example, a hollow tube (e.g., a single-wall borophene tube or fiber or the like) or the like, comprises, consists essentially of, or consists of a single layer (e.g., first layer) of boron atoms (e.g., a single layer of boron atoms). In various examples, a single layer (e.g., first layer) of boron atoms is borophene or a borophene layer or a 2D layer (e.g., atomically thin or the like) of boron atoms. In various examples, each boron atom is independently covalently bonded to at least two other boron atoms (e.g., 2, 3, 4, or 5 other boron atoms). In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) comprises at least two layers (e.g., second layer, third layer, fourth layer, or the like) (e.g., concentric layers) of boron atoms, which may be a multi-wall boron tube, a multi- wall borophene tube, or the like. Each of the at least two layers (e.g.. concentric layers) independently comprises, consists essentially of, or consists of boron atoms (e.g., a single layer of boron atoms (such as, for example, borophene or a borophene layer), where each boron atom is covalently bonded to at least two other boron atoms (e.g., 2, 3, 4, or 5 other boron atoms)) and is disposed on a layer or layers (e.g., the first layer or the like) of boron atoms (e.g., a single layer of boron atoms, where each boron atom is covalently bonded to at least two other boron atoms (e.g., 2, 3, 4, or 5 other boron atoms)). In various examples, atleast a portion, substantially all, or all of the boron atoms of a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) are oxidized. In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) is / are not subjected to any post-formation processes.

[0034] In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (or a layer or layers thereof independently) comprises, consists essentially of, or consists of (or is) one or more or a plurality of hexagonal pyramidal units or groups (such as, for example, dovetailed hexagonal pyramidal units or groups or the like), icosahedral units or groups, or a structural analog or analogs thereof, or the like, or any combination thereof. In various examples, each hexagonal pyramidal units or group (such as, for example, a dovetailed hexagonal pyramidal unit or group or the like), icosahedral unit or group, or the structural analog or analogs thereof, or the like, or the combination thereof comprises boron atoms (e.g., a plurality of boron atoms) (e.g., where each of the boron atoms is independently covalently bonded to at least two other boron atoms (e.g., 2, 3, 4, or 5 other boron atoms)).

[0035] A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (or a layer or layers thereof) may be at least partially crystalline. In various examples, one or more or all of a single layer or layers of a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) is / are independently at least partially, substantially, or completely crystalline. In various examples, one or more or all of a single layer or layers a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) is / are independently single crystalline or comprises one or more crystalline domain(s). In various examples, one or more or all of a single layer or layers a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) is / are independently comprises one or more crystalline domain(s), where the crystalline domain(s) independently comprise a size (e.g., one or more linear dimension(s) or the like) of about 5 nm to about 50 nm, including all 0.1 nm values and ranges therebetween (e.g., about 10 nm to about 50 nm). A size (e.g., a linear dimension or the like) of a crystalline domain can be determined by methods known in the art. In various examples, a crystalline domain is determined by electron microcopy (such as, for example, transmission electron microscopy or the like). In various examples, domain size is determinedusing a diffraction or a scattering measurement or measurements, such as, for example, x-ray scattering, electron scattering, or the like, or any combination thereof.

[0036] A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (or a layer or a layers thereof independnetly) may comprise one or more phase(s), at least two or more or all of which may be distinct (e.g., compositionally distinct, structurally distinct, or the like) phases. In various examples, at least a portion, substantially all, or all of each of the single layer(s) a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) independently is / are or comprisesphase borophene, / S phase borophene, 6e phase borophene, a phase borophene, Pmmn phase borophene, Pmmm phase borophene, a-icosohedral phase borophene, p-icosohedral phase borophene, a structural analog thereof, or the like, or any combination thereof.

[0037] A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (or a layer or layers thereof independently) may be metallic, comprise a metallic or semi-metallic electronic structure, exhibit metallic or semi-metallic behavior, or the like. In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) comprises or exhibits a metallic electronic structure. In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) exhibits semiconducting behavior with a band gap of 0.1 eV (eV = electron volt(s)) to about 0.4 eV, including all 0.005 eV values and ranges therebetween. A band gap of a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) can be determined by methods known in the art. In various examples, a band gap of a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) is determined by optical absorption spectroscopy, scanning tunneling microscopy, density functional theory calculation, or the like, or any combination thereof.

[0038] A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) can have various dimensions. In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) comprises (or has) a length (such as, for example, a longest longitudinal dimension or axis or the like) of about 50 nm (nm = nanometer(s)) to about 5 pm (pm = micron(s)), including all 0.1 nm values and ranges therebetween (e.g., about 100 nm to about 1 pm, about 100 to about 2 pmabout 200 nm to 1 pm, or about 200 nm to about 2 pm). In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) comprises (or has) a linear, cross-sectional dimension (such as, for example, a radius (e.g., assuming a circular cross section or the like) or the like) of about 1 nm to about 2 pm, including all 0.1 nm values and ranges therebetween (e.g., about 1 nm to about 200 nm, about 1 nm to about 500 nm, or about 100 nm to about 500 nm). A dimension or dimensions of a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) can be determined by methods known in the art. In various examples, a dimension or dimensions of a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) is / are determined by electron microscopy (such as, for example, transmission electron microscopy, scanning electron microscopy, scanning tunneling microscopy, or the like), atomic force microscopy, confocal and / or fluorescence optical microscopy, or the like, or any combination thereof.

[0039] A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) can have one or more desirable properties. In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) exhibits an optical property (e.g., a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) is translucent (such as, for example, translucent at one or more or all visible wavelengths (such as, for example, 380 nm to 750 nm, including all integer wavelength values and ranges therebetween)); or a thermal property (e.g., a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) is stable (e.g.. under electron beam irradiation under vacuum or the like) at about 300 KeV), or the like, or both). By “stable” it is meant that a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) does not exhibit observable degradation or no degradation, observable damage or no damage, or any combination thereof at about 300 KeV (e.g., under electron beam irradiation under vacuum) or more. Degradation (such as, for example, structural changes, or the like, or any combination thereof) can observed, determined, quantified or the like by methods known in the art. In various examples, degradation and / or damage is observed, determined, quantified or the like by an electron microscopy method (such as, for example, transmission electron microscopy or the like), or the like, or any combination thereof.[0040| A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) can exhibit a desirable defect level. In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (or a layer or layers thereof) does not exhibit observable defect(s). Non-limiting examples of defects include atom vacanc(ies), interstitial atom(s), domain boundar(ies), polymorph(s), protrusion(s), or the like, or any combination thereof. The presence and / or absence of a defect or defects can be determined by methods known in the art. In various examples, a crystalline domain is determined by electron microcopy (such as, for example, transmission electron microscopy (TEM) (e.g. high-resolution TEM, which may be BF (bright field)-HRTEM or the like, or the like) (e.g., fast Fourier transform of HRTEM images or the like), scanning transmission electron microscopy (STEM), or the like), electron diffraction, or the like, or any combination thereof.

[0041] A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (or a layer or layers thereof) can be formed from a rolled sheet of boron atoms or the like. In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (or a layer or layers thereof) is formed from a rolled borophene sheet or sheets (e.g., a rolled exfoliated borophene sheet or sheets or the like) (or each layer thereof is independently formed from a rolled borophene sheet (e.g., a rolled exfoliated borophene sheet or the like)). In various examples, each layer or the layers (e.g., borophene sheet(s) thereof) of a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) independently comprises out-of-plane triangular atomic ridge-like structures (e.g., as shown in FIG. 4) or the like.

[0042] In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (or a layer or layers thereof) is / are formed without any vacuum deposition (e.g., molecular beam epitaxy (MBE), atomic layer deposition (ALD), or the like), without any laser ablation, without any chemical treatment, without use of any gases, or any combination thereof. In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (or a layer or layers thereof) is not a nanowire, a nanorod, or a bamboo-like nanotube, or the like. In various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (or a layer or layers thereof) is not embedded in or attached or grown from a substrate(such, as for example, a metal substrate or the like) or the like. Tn various examples, a hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) is a free-standing hollow tube, free-standing hollow fiber, or the like (such as, for example, a free-standing borophene tube, a free-standing borophene fiber, or the like).

[0043] In an aspect, the present disclosure provides compositions. In various examples, a composition comprises one or more or a plurality of hollow tube(s). hollow fiber(s). or the like (such as, for example, borophene tube(s), borophene fiber(s), or the like), or any combination thereof of the present disclosure (such as, for example, hollow tube(s), hollow fiber(s), or the like (such as, for example, borophene tube(s), borophene fiber(s), or the like) or any combination thereof made by a method of the present disclosure). In various examples, a composition or compositions is / are suitable or configured for a use of the present disclosure. In various examples, a composition or compositions is / are used in a device of the present disclosure. Nonlimiting examples of compositions are disclosed herein.

[0044] In various examples, a composition comprises a plurality of hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like), or any combination thereof. In various examples, at least a portion, substantially all, or all of the hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like), or any combination thereof in a composition are substantially the same or the same (e.g., chemically the same, structurally the same, or both). In various examples, two or more or all of the hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like), or any combination thereof in a composition are different (e.g., chemically and / or compositionally different, structurally different, or both). In various examples, the hollow tube(s), hollow fiber(s), or the like (such as, for example, borophene tube(s), borophene fiber(s), or the like), or the combination thereof of a composition is / are not subjected to any postformation processes.

[0045] A composition can comprise various hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like), or any combination thereof. In various examples, a composition comprises hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like), or any combination thereof independently comprising (or having) (or at least 80%, at least 90%, at least 95%, at least 98%. or at least 99%, or at least 99.5% of the hollow tubes, hollow fibers, or the like (such as, forexample, borophene tubes, borophene fibers, or the like), or any combination thereof comprise (or have)) a length (such as, for example, a longest longitudinal dimension or axis or the like) and / or the hollow tubes, hollow fibers, or the like (such as. for example, borophene tubes, borophene fibers), or any combination thereof of a composition comprise (or have) an average length (such as, for example, an average longest longitudinal dimension or axis or the like) of about 50 nm to about 5 pm, including all 0.1 nm values and ranges therebetween (e.g., about 100 nm to about 1 pm, about 100 to about 2 pm about 200 nm to 1 pm, or about 200 nm to about 2 pm). In various examples, a composition comprises hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like), or any combination thereof independently comprising (or having) (or at least 80%, at least 90%, at least 95%, at least 98%, or at least 99%, or at least 99.5% of the hollow tubes, hollow fibers, or the like (such as. for example, borophene tubes, borophene fibers, or the like), or any combination thereof comprises (or has)) a linear, cross-sectional dimension (such as, for example, a radius (assuming a circular cross section) or the like) or the hollow tubes, hollow fibers, or the like (such as. for example, borophene tubes, borophene fibers, or the like), or any combination thereof comprise (or have) an average linear, cross-sectional dimension (such as, for example, an average radius (assuming a circular cross section) of about 1 nm to about 2 pm, including all 0.1 nm values and ranges therebetween (e.g., about 1 nm to about 200 nm, about 1 nm to about 500 nm, or about 100 nm to about 500 nm). In various examples, at least a portion, substantially all, or all of the boron atoms of one or more, substantially all, or all of the borophene tube(s) (such as, for example, one or more hollow fiber(s) or one or more hollow tube(s)) is / are oxidized.

[0046] In an aspect, the present disclosure provides methods of making hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like), or any combination thereof and compositions. In various examples, a method comprises mechanically mixing, agitating, or the like, or any combination thereof one or more boron precursor(s) that are under pressure (such as, for example, in a closed system or the like). In various examples, a method produces a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof and / or a composition of the present disclosure. Non-limiting examples of methods of making hollow tube(s), hollow fiber(s), or the like (such as, for example, borophene tube(s),borophene fiber(s), or the like), or any combination thereof and / or compositions are disclosed herein.

[0047] In various examples, a method of making a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof comprises, consists essentially of, or consists of: a mechanically mixing, agitating (e.g.. sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like a composition (such as, for example, a reaction mixture or the like) comprising: one or more boron precursor(s); and one or more solvent(s), under pressure (e.g., elevated pressure, which may be greater than ambient pressure) (which may be autogenous pressure or the like). In various examples, mechanically mixing, agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like, or any combination thereof results in exfoliation of at least a portion of the boron precursor(s). In various examples, mechanically mixing, agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like, or any combination thereof results in exfoliation of at least a portion of the boron precursor(s) and production of at least one intermediate (such as, for example, borophene sheet(s) or the like).

[0048] A composition (e.g., a reaction mixture or the like) can comprise various boron precursor(s). A single boron precursor or any combination of two or more different (e.g., chemically and / or compositionally different, structurally different, or both) boron precursors can be used. Non-limiting examples of boron precursor(s) include boron powders (such as, for example, crystalline boron powders, mixed-phase crystalline boron flakes, polymorphs of boron crystals or the like), and the like, and any combination thereof.

[0049] A boron precursor can have various sizes. In various examples, a boron precursor or precursors independently comprises (or has) a length (such as, for example, a longest longitudinal dimension or axis or the like) or an average length (such as, for example, an average longest longitudinal dimension or axis or the like) of about at about 150 nm to about 3,500 nm or more (e.g., a 100 microns or more or 200 microns or more), including all 0.1 nm values and ranges therebetween (e.g., about 150 nm to about 2,000 nm, or about 150 nm to about 2,500 nm).[0050| A composition (e.g., a reaction mixture or the like) can comprise various solvent(s). A single solvent or any combination of two or more different (e.g., chemically and / or compositionally different, structurally different, or both) solvents, which may be present in the same or in two or more different amounts, can be used. In various examples, a solvent exhibits one or more or all of: a vapor pressure of about 0.05 bar to about 1.2 bar (e.g., at room temperature or the like), including all 0.01 bar values and ranges therebetween (e.g.. about 0.05 bar to about 0.7 bar (e.g., at room temperature or the like), about 0.5 bar to about 0.7 bar (e.g., at room temperature or the like)), about 0.5 bar to about 1.2 bar (e.g., at room temperature or the like), about 0.2 bar to about 0.5 bar (e.g., at room temperature or the like), or about 0.25 bar (e.g., at room temperature or the like); a boiling point of about 40 °C to about 75 °C, including all 0.1 °C values and ranges therebetween (e.g.. about 50 °C to about 60 °C): a boiling point vapor pressure (or a critical pressure or the like) of about 46 bar to about 46.9 bar (e.g., at about 373 K to about 510 K, including all 0.1 K values and ranges therebetween), including all 0.1 bar values and ranges therebetween (e.g., about 46.4 bar to about 46.9 bar (e.g., at about 373 K to about 510 K, including all 0.1 K values and ranges therebetween)); miscibility in benzene, diethyl ether, methanol, chloroform, ethanol, or the like, or any combination thereof; or a density of about 0.784 (e.g., 0.7845) g / cm3. Non-limiting examples of solvents include ketones (e.g., acetone, which may be ACS grade acetone or the like, structural analogs thereof, and the like), structural analogs thereof, and the like, and any combination thereof.

[0051] A method can be earned out in a composition (e.g., in a reaction mixture) comprising or comprising one or more boron precursor(s) and one or more solvent(s) that further comprises various atmospheres. In various examples, a method is carried out in a composition (e.g., in a reaction mixture comprising one or more boron precursor(s) and one or more solvent(s) further comprises an ambient environment (such as. for example, the ambient environment of the composition (e.g., the reaction mixture) or the ambient environment present during formation of the composition (e.g., the reaction mixture), such as, for example, air (e.g., ambient air or the like) or the like. In various examples, the atmosphere of the mechanically mixing, agitating, or the like comprises (or is) the ambient environment (such as, for example, the ambient environment of the composition (e.g., the reaction mixture) or the ambient environment present during formation of the composition (e.g., the reaction mixture), such as, for example, air (e.g., ambient air or the like) or the like.[0052J Various mechanically mixing, agitating, or the like, or any combination thereof can be used. In various examples, mechanically mixing, agitating, or the like is micromechanic ally mixing or agitating, micromechanical exfoliating, or the like, or any combination thereof and / or agitating is sonochemical agitating or the like. In various examples, mechanically mixing, agitating (e.g., sonochemically exfoliating, intercalation-mediated exfoliation (such as, for example, by sonochemical agitating or the like), or the like, or any combination thereof), or the like, or any combination thereof results in exfoliation of at least a portion of the boron precursor(s). In various examples, mechanically mixing, agitating (e.g., sonochemically exfoliating, ultrasonically agitating, intercalation-mediated exfoliating, or the like, or any combination thereof), or the like, or any combination thereof results in exfoliation of at least a portion of the boron precursor(s) and production of at least one intermediate (such as, for example, borophene sheet(s) or the like). In various examples, a mechanically mixing, agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like, or any combination thereof results in cavitation, production of shock waves, or the like, or any combination thereof and / or formation of microbubbles or the like.

[0053] A mechanically mixing, agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like, or any combination thereof can be performed under various conditions. A mechanically mixing, agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like, or any combination thereof can comprise one or more step(s) and each step can be performed under the same or different conditions as other steps.

[0054] In various examples, an agitating (such as, for example, sonochemical agitating or the like) or the like comprises a compression and rarefaction cycle rate of about 37 kHz to about 80 kHz, including all 0.1 Hz values and ranges therebetween (e.g., about 37 to about 40 kHz or about 40 kHz). In various examples, a mechanically mixing or agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof) or the like or any combination thereof comprises about 40,000 compression and rarefaction cycles in about 1 second. In these examples, the pressure may be about 29 to about 36 atm, including all 0.1 atm values and ranges therebetween.[0055| A mechanically mixing, agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like, or any combination thereof can be earned out at various temperatures. In various examples, a mechanically mixing, agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like is carried out at a temperature of about 40 °C to about 60 °C, including all 0.1 °C values and ranges therebetween (e.g., about 45 °C). In various examples, a mechanically mixing, agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like, or any combination thereof is carried out at a temperature up to or about a lowest degradation temperature of a boron precursor or the boron precursors or a solvent or the solvents. In various examples, in the case of multiple steps, each step is performed at the same or different temperature as the other steps.

[0056] A mechanically mixing, agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like, or any combination thereof can be carried out at various pressures. In various examples, a mechanically mixing, agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like is carried out at about 29 atm (atm = atmosphere(s)) to about 36 atm, including all 0.1 atm values and ranges therebetween. In various examples, in the case of multiple steps, each step is performed at the same or different pressure as the other steps. In various examples, the pressure is not externally applied or exogenous pressure. In various examples, the pressure results from the closed nature of the container and the (p,P,T) relationship for the solvent(s) (its equation of state) (which may be referred to as autogenous pressure).

[0057] A mechanically mixing, agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like can be carried out for various times. A mechanically mixing, agitating (e.g., sonochemical exfoliation, ultrasonic exfoliation, intercalation-mediated exfoliation, or the like, or any combination thereof), or the like time may depend on factors such as, for example, one or more or all of (if applicable) temperature, pressure, intensity of the mechanically mixing, agitating, or the like. In various examples, reaction times range from about minutes (e.g., two minutes) to about 24 hours, including all integer minute values and ranges therebetween (e.g., about 8hours). In various examples, each step is performed at the same or different time as the other steps.

[0058] At least a portion, substantially all, or all of the borophene tube or tubes (such as, for example, a hollow fiber or fibers or a hollow tube or tubes) produced in a method may be oxidized or the like. In various examples, a method further comprises oxidizing at least a portion, substantially all, or all of a product (e.g.. borophene tube(s) (such as, for example, hollow fiber(s), hollow tube(s), or the like) or a composition) (e.g., product formed from an agitated (e.g., sonochemical exfoliated, intercalation-mediated exfoliated, or the like, or any combination thereof) composition). In various examples, a method further comprises contacting at least a portion, substantially all, or all of a product (e.g., hollow fiber(s), hollow tube(s), or the like or a composition) (e.g., formed from an agitated (e.g., sonochemical exfoliated, intercalation- mediated exfoliated, or the like, or any combination thereof) composition) with one or more oxidizing agent(s). Non-limiting examples of oxidizing agents include peroxides (such as, for example, hydrogen peroxide, structural analogs thereof, and the like), molecular oxygen, ozone, oxidizing acids (such as, for example, nitric acid and the like), chlorate ions, chlorite ions, or the like).

[0059] At least a portion, substantially all, or all of the borophene tube or tubes (such as, for example, a hollow fiber or fibers or a hollow tube or tubes) or oxidized structural analogs thereof produced in a method may be isolated. In various examples, a method further comprises isolation of a product (e.g., a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof, or a composition) (e.g., formed from a mechanically mixed or agitated (e.g., sonochemical exfoliated, ultrasonically exfoliated, intercalation-mediated exfoliated, or the like, or any combination thereof) composition (e.g., a reaction mixture). In various examples, a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof or a composition formed by a method as described herein is / are isolated. Suitable isolation methods are known in the art. In various examples, at least a portion, substantially all, or all of the hollow fiber(s), hollow tube(s), or the like or the composition is / are isolated by precipitation, centrifugation, filtration (such as, ultrafiltration or the like), dialysis, or the like (any of which may be size selective). In various examples, a method further comprises isolating at least a portion,substantially all, or all of the hollow fiber(s), hollow tube(s), or the like or the composition (e.g., in one or more fraction(s), which may be size-selective fractions or the like).

[0060] In various examples, a method does not comprise a process or a processes such as, for example, vacuum deposition (e.g., molecular beam epitaxy (MBE), atomic layer deposition (ALD), or the like), any laser ablation, any chemical treatment, use of any gases (such as, for example, reactive gases or the like), or any combination thereof. In various examples, a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof is / are not a nanowire or nanowires, a nanorod or nanorods, a bamboo-like nanotube or nanotubes, or the like. In various examples, a borophene tube or tubes (such as, for example, a hollow fiber or fibers or a hollow tube or tubes) is / are not embedded in a metal substrate or the like. In various examples, a borophene tube or tubes (such as, for example, a hollow fiber or fibers or a hollow tube or tubes) or a composition is / are not subjected to any post-formation processes.

[0061] In an aspect, the present disclosure provides uses of a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof or a composition or compositions of the present disclosure. Non-limiting examples of compositions are disclosed herein.

[0062] A hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof or a composition or compositions can be used in various applications. Non-limiting examples of applications include energy storage and / or generation, in optoelectronic applications, in gas storage (such as, for example, hydrogen gas storage, halogen gas storage, or the like), in sensing applications (such as, for example, gas sensing, light sensing, strain sensing, explosive material sensing, or the like), in field emission applications, in thermal conductivity applications, in molecular electronic applications, in structural applications, in fiber / fabric applications, in biomedical applications (such as, for example, disease diagnosis, or the like), in electronic applications (such as, for example, in electronic / semiconductor chip, spintronic chip, or the like), in molecular electronic applications, in filtration applications, in catalysis applications, as conductive adhesives, as thermal materials, as reinforcing materials, and the like.

[0063] In various examples, a material comprises a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, orthe like), or any combination thereof or a composition or compositions. Tn various examples, a material is a conductive adhesive, a thermal material, a sensor material, a reinforcing material, or the like, or any combination thereof.

[0064] In an aspect, the present disclosure provides devices. In various examples, a device comprises a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof or a composition or compositions of the present disclosure. Non-limiting examples of devices are disclosed herein.

[0065] In various examples, a device is a sensor, an actuator, a detector, or the like. In various examples, a device comprises a sensor, an actuator, a detector, or the like, or any combination thereof. Non-limiting examples of devices include energy storage and / or generation devices, optoelectronic devices, gas storage devices (such as, for example, hydrogen gas storage devices, halogen gas storage devices, or the like), sensing devices (such as, for example, sensors (e.g., surface-enhanced Raman scattering (SERS) detection devices or the like) and the like) (such as, for example, gas sensing devices, light sensing devices, strain sensing devices, explosive material sensing devices, or the like), field emission devices, thermal conductivity devices, molecular electronic devices, filtration devices, and the like, and any combination thereof. Non-limiting examples of sensors include gas sensors, light sensors, strain sensors, explosive material sensors, biosensors, and the like.

[0066] In various examples, a device comprises one or more electrode(s) and one or more or all of the electrode(s) (such as, for example, cathode(s), anode(s), or the like, or any combination thereof) comprises a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof or a composition or compositions. In various examples, a device comprises one or more substrates(s) and one or more or all of the substrate(s) comprises (or is) a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof or a composition or compositions. In various examples, a device comprises a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof or a composition or compositions disposed on a substrate (such as, for example, a glass substrate, a silicon substrate, a glassy electrode (e.g., a cathode or an anode), orthe like, which may be suitable or configured for sensing, energy storage, an energy generation platform, or the like.

[0067] The following Statements provide examples of hollow tubes, hollow fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), compositions, methods of making a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof, compositions, uses of a hollow tube or tubes, a hollow fiber or fibers, or the like (such as, for example, a borophene tube or tubes, a borophene fiber or fibers, or the like), or any combination thereof, and devices:Statement 1. A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (e.g., a single-wall boron tube, a borophene tube (such as, for example, a single- wall borophene tube or the like, or the like) comprising, consisting essentially of, or consisting of a single layer (e.g., first layer) of boron atoms (e.g., a single layer of boron atoms (such as, for example, borophene or a borophene layer or a 2D layer (e.g.. atomically thin or the like) of boron atoms), where each boron atom is independently covalently bonded to at least two other boron atoms (e.g., 2, 3, 4, or 5 other boron atoms).Statement 2. A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) according to Statement 1, where the single layer of boron atoms is at least partially, substantially, or completely crystalline.Statement 3. A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) according to Statement 1 or 2, where at least a portion, substantially all, or all of the single layer of boron atoms is or comprises phase borophene, 3i 2 phase borophene, 5e phase borophene, a phase borophene, Pmmn phase borophene. Pmmm phase borophene. a-icosohedral phase borophene, [3-icosohedral phase borophene, a structural analog thereof, or the like, or any combination thereof (e.g., as shown in FIG. 10).Statement 4. A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like)according to any one of the preceding Statements, where the single layer of boron atoms comprises one or more or a plurality of hexagonal pyramidal units or groups (such as, for example, dovetailed hexagonal pyramidal units or groups or the like), icosahedral units or groups, or a structural analog or analogs thereof, or the like, or any combination thereof.Statement 5. A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (which may be a multi-wall boron tube, a multiwall- wall borophene tube, or the like) according to any one of the preceding Statements, further comprising one or more or two or more additional layers (e.g., second layer, third layer, fourth layer, or the like) (e.g., concentric additional layer(s)), where each additional layer comprises, consists essentially of, or consists of boron atoms (e.g., a single layer of boron atoms (such as, for example, borophene or a borophene layer), where each boron atom is covalently bonded to two other boron atoms) and is disposed on a layer or layers (e.g., the first layer or the like) of boron atoms (e.g., a single layer of boron atoms, where each boron atom is covalently bonded to two other boron atoms).Statement 6. A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) according to any one of the preceding Statements, where the hollow tube or fiber comprises (or has) a length (such as, for example, a longest longitudinal dimension or axis or the like) of about 50 nm (nm = nanometer(s)) to about 5 pm (pm = micron(s)), including all 0.1 nm values and ranges therebetween (e.g., about 100 nm to about 1 pm, about 100 to about 2 pm about 200 nm to 1 pm, or about 200 nm to about 2 pm).Statement 7. A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) according to any one of the preceding Statements, where the hollow tube or fiber comprises (or has) a linear, cross-sectional dimension (such as, for example, a radius (e.g., assuming a circular cross section or the like) or the like) of about 1 nm to about 2 pm, including all 0.1 nm values and ranges therebetween (e.g., about 1 nm to about 200 nm, about 1 nm to about 500 nm, or about 100 nm to about 500 nm).Statement 8. A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) according to any one of the preceding Statements, where at least a portion, substantially all, or all of the boron atoms are oxidized.Statement 9. A hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) according to any one of the preceding Statements, where the hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) exhibits one or more or all of the following: an optical property - the hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) istranslucent; or a thermal property - the borophene or borophene tube or hollow tube or the like is stable at least at about 300 KeV, or both.Statement 10. A composition comprising a plurality of hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like, or the like), or any combination thereof of the present disclosure (e.g., a plurality of hollow tubes, hollow fibers, or the like (such as. for example, borophene tubes, borophene fibers, or the like, or the like), or any combination thereof independently according to any one of Statements 1-9).Statement 11. A composition according to Statement 10, where the hollow tubes, the hollow fibers, or the like (such as, for example, the borophene tubes, the borophene fibers, or the like) of the plurality of hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like, or the like) independently comprises (or has) (or at least 80%, at least 90%, at least 95%, at least 98%, or at least 99%, or at least 99.5% of the hollow tubes or hollow fibers comprises (or has)) a length (such as, for example, a longest longitudinal dimension or axis or the like) or the hollow tubes, the hollow fibers, or the like (such as, for example, the borophene tubes, the borophene fibers, or the like) of the plurality of hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like, or the like) comprise (or have) an average length (such as, for example, an average longest longitudinal dimension or axis or the like) of about 50 nm to about 5 pm, including all 0.1 nm values and ranges therebetween (e.g., about 100 nm to about 1 pm, about 100 to about 2 pm about 200 nm to 1 pm, or about 200 nm to about 2 pm).Statement 12. A composition according to Statement 10 or 11, where the hollow tubes, the hollow fibers, or the like (such as, for example, the borophene tubes, the borophene fibers, or the like) of the plurality of hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like, or the like) independently comprise (or have) (or at least 80%, at least 90%. at least 95%, at least 98%, or at least 99%, or at least 99.5% of the hollow tubes or hollow fibers) comprises (or has) a linear, cross-sectional dimension (such as, for example, a radius (assuming a circular cross section) or the like) or the hollow tubes, the hollow fibers, or the like (such as, for example, the borophene tubes, the borophene fibers, or the like) of the plurality of hollow tubes, hollow fibers, or the like (such as, for example, borophene tubes, borophene fibers, or the like, or the like) comprise (or have) an average linear, cross-sectional dimension (such as, for example, an average radius (assuming a circular cross section) of about 1nm to about 2 pm, including all 0.1 nm values and ranges therebetween (e.g., about 1 nm to about 200 nm, about 1 nm to about 500 nm, or about 100 nm to about 500 nm).Statement 13. A method of making hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) (such as, for example, hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) of the present disclosure (e.g., hollow tube, a hollow fiber, or the like (such as, for example, a borophene tube, a borophene fiber, or the like) of according to any one of Statements 1-9 or the like) and / or a composition of the present disclosure (e.g., composition according to any one of Statements 10-12, or the like) comprising, consisting essentially of, or consisting of: mechanically mixing, agitating (e.g., sonochemically agitating, ultransonically agitating or the like) (e.g., sonochemically exfoliating, ultrasonically exfoliating, intercalation-mediated exfoliating, or the like, or any combination thereof), or the like, or any combination thereof a composition (such as, for example, a reaction mixture or the like) comprising: one or more boron precursor(s); and one or more solvent(s), under pressure (e.g., elevated pressure, which may be greater than ambient pressure) (which may be autogenous pressure or the like), where the hollow tube, the hollow fiber, or the like (such as, for example, the borophene tube, the borophene fiber, or the like) or the composition is formed. Statement 14. A method according to Statement 13, where the one or more boron precursor(s) is / are independently chosen from boron powders (such as, for example, crystalline boron powders, mixed-phase crystalline boron flakes, polymorphs of boron crystals or the like), and the like, and any combination thereof.Statement 15. A method according to Statement 13 or 14, where the one or more boron precursors(s) independently comprises (or has) a length (such as, for example, a longest longitudinal dimension or axis or the like) or an average length (such as, for example, an average longest longitudinal dimension or axis or the like) of about 150 nm to about 3,500 nm or more (e.g., a 100 microns or more or 200 microns or more), including all 0.1 nm values and ranges therebetween (e.g., about 150 nm to about 2,000 nm, about 150 nm to about 2,500 nm, or about 150 nm to about 3,000 nm).Statement 16. A method according to any one of Statements 13-15, where the one or more solvent(s) independently exhibit(s) one or more or all of: a vapor pressure of about 0.05 bar to about 1.2 bar (e.g., at room temperature or the like), including all 0.01 bar values and rangestherebetween (e.g., about 0.05 bar to about 0.7 bar (e.g., at room temperature or the like), about 0.5 bar to about 0.7 bar (e.g., at room temperature or the like)), about 0.5 bar to about 1.2 bar (e.g., at room temperature or the like), about 0.2 bar to about 0.5 bar (e.g., at room temperature or the like), or about 0.25 bar (e.g., at room temperature or the like); a boiling point of about 40 °C to about 75 °C, including all 0.1 °C values and ranges therebetween (e.g., about 50 °C to about 60 °C): a boiling point of about 40 °C to about 75 °C, including all 0.1 °C values and ranges therebetween (e.g., about 50 °C to about 60 °C); a boiling point vapor pressure (or a critical pressure or the like) of about 46 bar to about 46.9 bar (e.g., at about 373 K to about 510 K, including all 0.1 K values and ranges therebetween), including all 0.1 bar values and ranges therebetween (e.g., about 46.4 bar to about 46.9 bar (e.g., at about 373 K to about 510 K, including all 0.1 K values and ranges therebetween)); miscibility in benzene, diethyl ether, methanol, chloroform, ethanol, or the like, or any combination thereof; or a density of about 0784 g / cm3(such as, for example, 0.7845 g / cm3).Statement 17. A method according to any one of Statements 13-16. where the solvent(s) is / are chosen from ketone(s) (e.g., acetone, which may be ACS grade acetone or the like), and the like, and any combination thereof.Statement 18. A method according to any one of Statements 13-17, where the mechanically mixing and / or agitating comprises (or is) micromechanically mixing or agitating, micromechanical exfoliating, sonochemically exfoliating, ultrasonically exfoliating, intercalation-mediated exfoliating, sonochemical agitating, intercalation-based exfoliation, or the like, or any combination thereof.Statement 19. A method according to any one of Statements 13-18, where the agitating (such as, for example, sonochemical agitating or the like) or the like comprises a compression and rarefaction cycle rate of about 37 kHz to about 80 kHz, including all 0.1 Hz values and ranges therebetween (e.g., about 37 to about 40 kHz or about 40 kHz) or comprises about 40.000 compression and rarefaction cycles in about 1 second.Statement 20. A method according to any one of Statements 13-19, where the pressure is about 29 to about 36 atm, including all 0.1 atm values and ranges therebetween.Statement 21. A method according to any one of Statements 13-20, the method further comprising oxidizing or the like at least a portion, substantially all, or all of the hollow tube.Statement 22. A method according to any one of Statements 13-21 , the method further comprising isolating or the like the hollow tube.Statement 23. Use of one or more hollow tube(s), hollow fiber(s), or the like (such as, for example, borophene tube(s), borophene fiber(s), or the like) or one or more composition(s) of the present disclosure (such as, for example, one or more hollow tube(s), hollow fiber(s), or the like (such as, for example, borophene tube(s), borophene fiber(s), or the like) independently of any one of Statements 1 to 9 and / or one or more composition(s) of any one of Statements 10 to 12 and / or hollow fiber(s) or hollow tube(s) or composition(s) made by a method of the present disclosure (e.g., one or more hollow tube(s), hollow fiber(s), or the like (such as, for example, borophene tube(s), borophene fiber(s), or the like) or composition(s) independently made by a method of any one of Statements 13 to 22)) in energy storage and / or generation, in optoelectronic applications, in gas storage (such as, for example, hydrogen gas storage, halogen gas storage, or the like), in sensing applications (such as, for example, gas sensing, light sensing, strain sensing, explosive material sensing, or the like), in field emission applications, in thermal conductivity applications, in molecular electronic applications, in structural applications, in fiber / fabric applications, in biomedical applications (such as, for example, disease diagnosis, or the like), in electronic applications (such as, for example, in electronic / semiconductor chip, spintronic chip, or the like), in molecular electronic applications, as conductive adhesives, as thermal materials, as reinforcing materials, in filtration applications, in catalysis applications, or the like.Statement 24. A device comprising one or more hollow tube(s), hollow fiber(s), or the like (such as, for example, borophene tube(s), borophene fiber(s). or the like) or one or more composition(s) of the present disclosure (such as, for example, one or more hollow fiber(s) or hollow tube(s) of any one of Statements 1 to 9 and / or one or more composition(s) of any one of Statements 10 to 12 and / or hollow tube(s), hollow fiber(s). or the like (such as. for example, borophene tube(s), borophene fiber(s), or the like) or composition(s) made by a method of the present disclosure (e.g., hollow tube(s), hollow fiber(s), or the like (such as, for example, borophene tube(s), borophene fiber(s), or the like) or composition(s) independently made by a method of any one of Statements 13 to 23)).Statement 25. A device according to Statement 24, where the device is or comprises an energy storage and / or generation device, an optoelectronic device, a gas storage device (such as, forexample, a hydrogen gas storage device, a halogen gas storage device, or the like), a sensing device (e.g., a sensor (e.g., a surface-enhanced Raman scattering (SERS) detection device or the like) (such as, for example, a gas sensing device, a light sensing device, a strain sensing device, an explosive material sensing device, a biosensing device, or the like), a field emission device, a thermal conductivity device, a molecular electronic device, a filtration device, or the like. Statement 26. A device according to Statement 24 or 25. where the device is a sensor (such as, for example, a gas sensor, a light sensor, a strain sensor, an explosive material sensor, a biosensor, or the like), an actuator, a detector, or the like.Statement 27. A device according to any one of Statements 25-26, where the sensor is a gas sensor, a light sensor, a strain sensor, an explosive material sensor, a biosensor, or the like, or any combination thereof.

[0068] The steps of the methods described in the various embodiments and examples disclosed herein are sufficient to produce one or more borophene tube(s) or a composition or to carry out a method of the present disclosure. Thus, in various examples, a method consists essentially of any combination of the steps of the methods disclosed herein. In various other examples, a method consists of such steps.

[0069] The following Examples are presented to illustrate the present disclosure. The Examples are not intended to be limiting in any manner.EXAMPLE 1

[0070] This example provides examples of hollow tubes, hollow fibers, and compositions of the present disclosure, and methods of making and uses of same.

[0071] It was suspected that the pressure needed to roll a borophene sheet could not be achieved using an open container. A closed glass PFTE lined bottle that could withstand pressure created by acetone solvent was used. The change from an open container to a sealed vessel unexpectedly led to formation of hollow tubes or hollow fibers (described herein). Direct synthesis (one-step) of hollow tubes and hollow fibers using acetone as a solvent was demonstrated. Detailed microscopic and spectroscopic tools were employed to establish the technique and materials produced.

[0072] A typical synthesis proceeded as follows. First, 1.5 gm of the as-received boron powder was dispersed in analytical-grade acetone, in a Borosil tube (Product Code: 9910010) with a PTFE liner cap. The temperature of the ultrasonicator was maintained at 45 °C and theexfoliation time was optimized as 8 hours. Tn the closed tube, bubble jets were formed inside the solvent and the pressure generated inside the Borosil glass tube was not released.

[0073] Acetone having a lone pair of electrons on its oxygen and borophene being electrophilic, it is expected that the borophene surface would adsorb acetone. In fact, acetone gets adsorbed onto graphene as well (E ads - -0.28 eV for graphene, as calculated by Wang et. al. in J. Mater. Chem. A, 2015, 3, 6282-6285). Thus, solvent- solute interactions play a huge role in exfoliation. Moreover, volatile solvents having low vaporization points such as acetone (vapor pressure of -0.25 bar at room temperature, boiling point of 329 K), toluene, benzene, IPA etc. will behave differently under ultrasonic agitation. In fact, solvent surface energy is another crucial factor for exfoliation of 2D sheets (Coleman et. al. in Accounts of Chemical Research. 2012, 46, 14-22). As mentioned in the following table, surface tensions for routine solvents at room temperature are in 20-75 mJ m-2range (see table below).

[0074] Ultrasonic waves induce compression and rarefaction cycles at a fast rate (40 kHz in our case). During rarefaction cycles, cavitation occurs, and thus leads to formation of transient microbubbles. Growth of the microbubble proceeds through rectified diffusion and coalescence in the transient cavitations. The microbubbles burst as the temperature rises to - 1900 K in the liquid phase, localized pressure inside the sonication reaches up to a value of 20 MPa (-0.4 meV / A2) and the heating / cooling rate can reach 109Ks1(see Suslick et. al., in JACS, 1986). For the cavitation to occur in liquid phase, the local temperature would be -1900 K which corresponds to -150 meV in energy (this is localized energy though in the cavitation region). Thus, heat energy locally generated in the cavitation region along with solvent surface energy and solute- solvent interactions would be responsible for the exfoliation of 2D materials. For acetone, surface energy is 24 mJ / m2which amounts to 1.5 meV / A2. All these contributions could exceed the total inter-layer coupling of n layers of borophene, leading to exfoliation of the last layer and an n-1 layer stack. Theoretical understanding of exfoliation has already beendeveloped (Jung et. al., Nano Lett. 2018, 18, 2759-2765). Borophene exfoliation energy is expected to be very close to that of the phosphorene as both of them are elemental 2D sheets and they have out-of-plane atomic ridge-like structures (rectangular in case of phosphorene and triangular in case of borophene). Thermal surplus energy of the order of 150 meV, localized in cavitation region along with solute- solvent interactions and solvent surface energy would be reasonably sufficient for structural transformations (metamorphism) in boron i.e., a- rhombohedral and P-rhombohedral structures to a-tetragonal structure.

[0075] The following was noted:A) As a consequence of the pressure inside the bottle, surface layers of powder were exfoliated and rolled to form a tube to minimize the surface area and edge length.B) The closed bottle containing boron powder dispersed in acetone after 8 hours was centrifuged and characterized for phase and purity.C) The borophene tubes have successfully been transferred onto various substrates such as: FIG. 1(a) thermally oxidized silicon (SiCL), FIG. 1(b) Indium Tin Oxide (ITO) and FIG. 1(c) Fluorine doped Tin Oxide (FTO).D) Single-layer borophene (SLB), multilayer (MLB), and an intermediate between tube and sheets were found (evident from SEM images).E) Highly pure borophene tubes were found without any impurities (evident from EELS (TEM)).

[0076] Results. Optical image demonstrates successful exfoliation of hollow tubes and fibers tubes on Si / SiO2 substrate. Tubes are clearly visible on the Si / SiOz substrate (FIG. 2).

[0077] High resolution transmission electron microscopy study of hollow tubes and fibers. Bright field and Dark field Imaging. Bright field TEM image (FIG. 3) shows the formation of a hollow tube. The homogenous contrast suggests the transparent nature of the tube. The bright field TEM image shows a large-scale hollow tube formation. The intensity scan from different regions of a hollow tube indicates the existence of few layers of boron (FIG. 4). The intensity from the hollow tube drastically reduces as compared to the amorphous background (FIG. 4). Higher intensity across the edges indicates the tube nature of borophene (FIG. 4). Total intensity scan indicates the uniform thickness of the hollow tube (FIG. 4). The size (length and diameter) of the hollow tube is 2.7 pm x 0.2 pm (FIG. 4).[0078| The local fast Fourier transform pattern of the nano tube demonstrates the overall crystalline nature of the hollow tube (FIG. 5). The local fast Fourier transform pattern from different region of the hollow tube suggests uniform crystallinity of the hollow tube (FIG. 6). The crystallinity is also maintained at the interface.[0079[ Electron energy loss spectroscopy (EELS) shows the characteristics B-K to confirm the existence of B atom in hollow tube (FIG. 7). EELS also confirms the purity of the material.

[0080] The HRTEM image (FIG. 8) exhibits (a) free standing section of a hollow tube and (b) a hollow tube on a lacey carbon grid. The magnified section of (a,b) hollow tube is shown in (c,d), respectively. The magnified image section (c,d) clearly shows the tube nature of the borophene. The higher contrast on the edge indicates the edge thickness of the tube.

[0081] The EDX mapping show the boron distribution from the hollow tube and C distribution from the background lacey carbon grid (FIG. 9). The EDX elemental mapping shows the absence of the other atomic species (FIG. 9).

[0082] The HAADF image and corresponding electron energy loss spectra scan (FIG. 10). The EELS spectra acquired from the selected area from the hollow tube (FIG. 10). The EELS spectra clearly shows the B-K edge from the hollow tube area (FIG. 10). The C-K edge arises from the background lacey carbon grid (FIG. 10).

[0083] Theoretical simulation suggests ripples in the highly flexible borophene sheet help to coil boron nanotubes from rippled borophenes (a representative structure is shown in FIG. 11). The plane structures transform into rippled structures with very small compression and weak perturbations, such as molecular adsorption, which are very likely to occur during functionalization, as well as in the presence of pressure within a closed sonication bottle. The compression energies of the rippled structures increase linearly and slowly with the increase of the compression. For example, from 10% to 20% compression along the planar direction increases compression energy by 0.1 eV in the rippled structure with periods of 2 units in the compressed direction. This suggests how the geometry of the borophene evolves with compression to form the boron nanotube. Additionally, the transition of the borophene phase from beta-12 to chi-3 has been observed during planar compression at around 30% of the sheet. This suggests the possibility of having the chi-3 dominated phase in the hollow nanotube.

[0084] When boron powder as received was not subjected to pressurized condition then the supernatant contained only sheets. The starting material used is boron powder (as received) andacetone was used as solvent for intercalation and exfoliation during sonochemical exfoliation. When boron powder was not kept under the pressurized condition only sheets were formed (FIG. 12).

[0085] When commercially available boron powder was not subjected to pressurized condition then the supernatant have mixed morphology of distorted spherical particles and some morphology resembled to thick fragmented / distorted sheets (FIG. 13). The starting material used is boron powder (ottokemi.com, <50 micro-meter, 99% Code- B 0063) and acetone was used as solvent for intercalation and exfoliation during sonochemical exfoliation.EXAMPLE 2

[0086] This example provides examples of uses of hollow tubes, hollow fibers, and compositions of the present disclosure.

[0087] Laser light Response of Hollow Tube at various wavelengths. Silicon wafers (1 cm2) were first cleaned by immersion in a soap solution and subjected to ultrasonic agitation for 20 minutes to remove surface-bound organic contaminants. This was followed by sequential ultrasonic cleaning in ethanol and deionized (DI) water for 20 minutes each to further purify the surface. A Piranha solution was then employed to eliminate any remaining organic and inorganic residues and to enhance the hydrophilicity of the Si surface. Subsequently, a borophene sheet or tube made as described in EXAMPLE 1 dispersion was drop-cast onto the cleaned wafer and thermally dried at 70 °C to ensure complete solvent evaporation. The prepared device was then characterized for its current-time (I-t) behavior using a four-point probe measurement setup (FIG. 14(a)— (c)).

[0088] The current-time (I-t) response was measured by first placing the device in the dark, then sequentially exposing it to red (650 nm), green (532 nm), and blue (405 nm) lasers, each undergoing multiple on / off cycles. Upon laser illumination, the current increased, reached a saturation point, and subsequently decreased when the laser was turned off. Among the three, the blue laser induced the most pronounced current change, while the red laser produced the smallest response. This trend is attributed to the higher photon energy associated with shorter wavelengths, with blue light carrying more energy than green or red light. All lasers used had a constant power output of 5 mW. As illustrated in the figure, the initial dark current was approximately 207 pA for both borophene sheet and tube. Upon laser exposure, the currentincreased to saturation levels of around 270 and 288 pA for red, 308 and 328 pA for green, and 340 and 362 pA for blue laser illumination for borophene sheet and tube, respectively.

[0089] The response % of both borophene sheet and tube was evaluated under red, green, and blue laser illumination. For the borophene sheet, the response values were 30.43%, 48.79%, and 64.25%, respectively, while the hollow tube exhibited enhanced responses of 39.13%, 58.45%, and 74.87% under the same conditions.

[0090] The hollow tube demonstrates higher sensitivity to visible light, effectively detecting red, green, and blue laser radiation with distinct photoresponse levels as compared to borophene sheet. Its enhanced responsivity, particularly under blue light, highlights its potential for broadband photodetection across the visible spectrum.EXAMPLE 3

[0091] This example provides examples of uses of hollow tubes, hollow fibers, and compositions of the present disclosure.

[0092] Electrode Fabrication. The polymerization electrolyte was formulated by dispersing 0.15 M pyrrole monomer in an acetonitrile solvent mixed with 0.1 M lithium perchlorate (LiCICh). A conductive polyp yrrole (PPy) layer was synthesized via electrochemical polymerization, transforming the monomeric precursor into a polymerized matrix. This electrochemical deposition produced a coherent PPy film adhering to the ITO substrate.

[0093] Cyclic voltammetry (CV) served as the driving method for initiating pyrrole polymerization. Over five consecutive CV sweeps spanning -0.2 V to 1.2 V at 50 mV s’1, a homogeneous PPy layer was electrodeposited onto the ITO surface. Subsequently, presynthesized hollow tubes (HTs) made as described in EXAMPLE 1 were deposited via dropcasting onto the PPy-coated substrate. To optimize adhesion and solvent removal, the composite was thermally treated at 50°C, ensuring a consistent dispersion of BTs across the polymer surface.

[0094] Caffeine Electrochemical Measurement. The ITO electrode underwent cyclic electropolymerization of pyrrole over five voltammetric cycles, operating between -0.2 V and 1.2 V with a 50 mV s’1sweep speed. Electrochemical analyses of bare and polymer-modified electrodes were conducted in two media: a 0.1 M KC1 inert electrolyte and a solution containing 50 pM caffeine. Caffeine quantification utilized a slower scan rate of 30 mV s’1. KC1 was selected as the electrolyte for its practicality, low hazard profile, and versatility inelectrochemistry. Its high aqueous solubility enables straightforward dissolution, while its reduced environmental and physiological risks make it preferable over more toxic alternatives.

[0095] Cyclic Voltammetry (CV) with the sensor explored caffeine’s electrochemical activity across a -1 V to 1 V span (FIG. 15). Bare ITO electrodes in caffeine-spiked solutions showed negligible charge transfer activity, whereas the sensor in blank KC1 lacked detectable signals. However, introducing caffeine induced distinct redox behavior in the modified electrode (BSs / PPy@ITO). Enhanced current intensities and subtle potential variations in the hybrid system suggest its composite architecture actively facilitates caffeine’s electron transfer processes, contrasting sharply with unmodified controls. When the sensor was modified with BTs, the BTs / PPy@ITO sensor showed an even greater enhancement in current density values compared to the BSs-based sensor. The enhancement in electrochemical response observed with BTs / PPy@ITO is attributed to the unique tubular morphology of hollow-tubes, which offers a higher surface-to-volume ratio, enhanced edge-plane exposure, and improved electron transport pathways compared to the planar structure of borophene sheets. This structural advantage allows for more efficient interaction with caffeine molecules and faster electron transfer kinetics. FIG. 16 presents a bar graph comparison of the oxidation peak current densities for BSs / PPy@ITO and BTs / PPy@ITO electrodes. The observed variation in current response highlights the distinct electrochemical behavior of the two modified electrode systems. Notably, the BTs / PPy@ITO electrode exhibits a higher oxidation peak current density compared to BSs / PPy@ITO, indicating enhanced charge transfer kinetics and improved electrochemical activity. This enhancement may be attributed to the specific surface properties or electronic interactions of the BTs component with the PPy matrix, which facilitate more efficient redox processes at the electrode-electrolyte interface. These findings suggest that the BTs-based platform could be more effective for applications requiring high electrochemical sensitivity.

[0096] These results demonstrate that the sensor delivers accurate and reliable measurements, underscoring its expected potential for real-world applications. Its design supports the development of portable, user-friendly devices for on-site caffeine analysis, which could significantly transform monitoring practices in both consumer goods and pharmaceutical sectors. This advancement not only contributes to better health risk management but also offers a versatile tool for research and industrial use, highlighting the sensor’s broader impact on enhancing safety, quality control, and regulatory compliance in everyday consumables.[0097| Although the present disclosure has been described with respect to one or more particular embodiments and / or examples, it will be understood that other embodiments and / or examples of the present disclosure may be made without departing from the scope of the present disclosure.

Claims

CLAIMS:

1. A hollow tube or a hollow fiber comprising a single layer of boron atoms, wherein each boron atom is independently covalently bonded to at least two other boron atoms.

2. The hollow tube or the hollow fiber of claim 1, wherein the single layer of boron atoms is at least partially, substantially, or completely crystalline.

3. The hollow tube or the hollow fiber of claim 1, wherein at least a portion, substantially all, or all of the single layer of boron atoms is or comprises phase borophene, / 3iz phase borophene, §6 phase borophene, a phase borophene, Pmmn phase borophene, Pmmm phase borophene, a- icosohedral phase borophene, 0-icosohedral phase borophene, a structural analog thereof, or any combination thereof.

4. The hollow tube or the hollow fiber of claim 1, wherein the single layer of boron atoms comprises one or more or a plurality of hexagonal pyramidal units, icosahedral units, or a structural analog or analogs thereof, or any combination thereof.

5. The hollow tube or the hollow fiber of claim 1 , further comprising two or more additional layers, wherein each additional layer independently comprises a single layer of boron atoms and is disposed on a layer or layers of boron atoms wherein each boron atom is covalently bonded to two other boron atoms).

6. The hollow tube or the hollow fiber of claim 1, wherein the hollow tube comprises a length of about 50 nm to about 5 pm.

7. The hollow tube or the hollow fiber of claim 1, wherein the hollow tube comprises a linear, cross-sectional dimension of about 1 nm to about 2 pm.

8. The hollow tube or the hollow fiber of claim 1, wherein at least a portion, substantially all, or all of the boron atoms are oxidized.

9. The hollow tube or the hollow fiber of claim 1, wherein the hollow tube is translucent and / or the hollow tube is stable at least at about 300 KeV.

10. A composition comprising a plurality of hollow tubes or hollow fibers of claim 1.

11. The composition of claim 10, wherein the hollow tubes or the hollow fibers of the plurality of hollow tubes or hollow fibers comprise an average length of about 50 nm to about 5 pm.

12. The composition of claim 10, the hollow tubes or the hollow fibers of the plurality of hollow tubes or hollow fibers comprise an average linear, cross-sectional dimension about 1 nm to about 2 pm.

13. A method of making a hollow tube or hollow fiber of claim 1 comprising: mechanically mixing and / or agitating a composition comprising: one or more boron precursor(s); and one or more solvent(s), under pressure, wherein the hollow tube or fiber is formed.

14. The method of claim 13, wherein the one or more boron precursor(s) is / are independently chosen from crystalline boron powders, mixed-phase crystalline boron flakes, polymorphs of boron crystals and any combination thereof.

15. The method of claim 13, wherein the one or more boron precursor(s) independently comprise a length of about 150 nm to about 3,500 nm.

16. The method of claim 13, wherein the one or more solvent(s) independently exhibit(s) one or more or all of: a vapor pressure of about 0.05 bar to about 1.2 bar; a boiling point of about 40 °C to about 75 °C;a boiling point vapor pressure or a critical pressure of about 46.4 bar to about 46.9 bar; miscibility in benzene, diethyl ether, methanol, chloroform, or ethanol, or any combination thereof; or a density of about 0.7845 g / cm3.

17. The method of claim 13, wherein the one or more solvent(s) is / are chosen from ketones and any combination thereof.

18. The method of claim 13, wherein the mechanically mixing and / or agitating comprises micromechanically mixing or agitating, micromechanical exfoliating, sonochemically exfoliating, ultrasonically exfoliating, intercalation-mediated exfoliating, or any combination thereof.

19. The method of claim 13, wherein the mechanically mixing and / or agitating is sonochemical agitating and the sonochemical agitating comprises a compression and rarefaction cycle rate of about 37 kHz to about 80 kHz.

20. The method of claim 13, wherein the pressure is about 29 to about 36 atm.

21. The method of claim 13, the method further comprising oxidizing at least a portion, substantially all, or all of the hollow tube or hollow fiber.

22. The method of claim 13, the method further comprising isolating the hollow tube or hollow fiber.

23. Use of hollow tube(s) or hollow fiber(s) of claim 1 in energy storage and / or generation, in optoelectronic applications, in gas storage, in sensing applications , in field emission applications, in thermal conductivity applications, in molecular electronic applications, in structural applications, in fiber / fabric applications, in biomedical applications, in electronic applications, in molecular electronic applications, in filtration applications, in catalysis applications, as conductive adhesives, as thermal materials, or as reinforcing materials.

24. A device comprising one or more hollow tube(s) and / or hollow fiber(s) of claim 1.

25. The device of claim 24, wherein the device comprises an energy storage and / or generation device, an optoelectronic device, a gas storage device, a sensing device, a field emission device, a thermal conductivity device, a molecular electronic device, or a filtration device.

26. The device of claim 24, wherein the device is a sensor, an actuator, or a detector.

27. The device of claim 26, wherein the sensor is a gas sensor, a light sensor, a strain sensor, an explosive material sensor, a biosensor, or any combination thereof.

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