One-dimensional lepidocrocite composition

Abstract

The present invention provides a method for converting binary and ternary titanium carbides, nitrides, borides, phosphides, aluminides and silicides into lepidocrocite nanofilaments in a bottom-to-top manner, which in some cases self-assemble into 2D flakes by immersing them in a quaternary ammonium solution at moderate temperatures. The resulting flakes may be C-containing layers that in turn consist of nanowires in cross-section, in some cases where some nanowires may have a length of several microns.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority and the benefit of U.S. Patent Application No. 63 / 398,782 (filed on August 17, 2022) and U.S. Patent Application No. 63 / 373,490 (filed on August 25, 2022). All of the foregoing applications are hereby incorporated by reference in their entirety for any purpose. Field of the Invention

[0003] The present disclosure relates to the fields of 1D and 2D materials and metal - oxide - based nanomaterials. Background Art

[0004] Nanostructured (NS) titanium dioxide TiO 2 has become and will continue to receive extensive research attention due to its unique physical and chemical properties and potential applications in many fields such as coating pigments, catalysis, photocatalysis, photoluminescence, gas sensors, solar energy, and fuel cells. 1-11 One - dimensional (1D) and two - dimensional (2D) materials have properties and characteristics that their three - dimensional (3D) solids do not possess. It can be said that the most important difference is that they have a much larger surface area. In terms of properties, low - dimensional solids allow for quantum confinement and more active catalytic sites. Therefore, there has long been a need in the art for 1D materials with useful properties. Summary of the Invention

[0005] A bottom - up, sol - gel - based, one - pot, inexpensive, and highly scalable process can be used to fabricate TiO - based 1D nanowires (NFs). 2 12 In our method, we simply immerse earth - abundant, non - toxic, water - insoluble binary and ternary titanium carbides, nitrides, borides, etc. in an aqueous solution of tetramethylammonium hydroxide (TMAH) at a temperature in the range of 50 to 85 °C for dozens of hours under ambient pressure. This process converts the precursors into 1D NFs, which then self - assemble into quasi - 2D flakes after being washed and filtered with water. 12 We show that the structure of our 1D NFs is based on lepidocrocite, hereafter referred to as 1DL. We also show that the NFs grow along the a or 200 direction and stack along the b and c directions. Brief Description of the Drawings

[0006] In the drawings, which are not necessarily to scale, the same numbers may describe similar components in different views. The same numbers with different letter suffixes may represent different instances of similar components. These draw Figure 1 ings generally illustrate, by way of example (but not by way of limitation), the various aspects discussed in this document. In the drawings: ​

[0007] Figure 1 : a) XRD patterns of two samples, one cleaned with ethanol; the other cleaned with ethanol and then with 0.5 M LiCl (see the method section). The positions of the (200) and (002) peaks at and ≈62° are crystallographic and not process-invariant. The positions of all other peaks are. Note the logarithmic scale on the y-axis. The yellow band outlines three arcs / rings previously observed in the SAD pattern of 2D flakes in TEM. 12 b) Schematic of the DFT-generated structure where TiO 2 bands stack perpendicular to the b-axis. All predicted non-basal planes are also traced. The rectangle in the lower right represents the unit cell with lattice parameters a and b. Note that while a is crystallographic, b is not, and b depends on the spacing between the bands chosen here as The same is true for stacking along 001. c) Schematic of the (001) plane assuming it is 2 Ti atoms wide. Along the c direction, the spacing between two adjacent Ti atoms or This results in peaks in the diffraction and SAD patterns at ≈ 12 The approximate "thickness" of the 2-atom-thick Ti bands is also shown in b and c - measured from the outermost O to the outermost O.

[0008] Figure 2 : Raman spectra of six samples that were cleaned differently (see the method section). In all cases, the resulting spectra are consistent with those of goethite. The inset shows the effect of laser power on the spectra. At high power, the material transforms from goethite to anatase. Laser powers of 10%, 50%, and 100% correspond to 6, 29, and 52 mW cm -2 .

[0009] Figure 3 : ABF TEM micrograph of a single 1D L NF bundle oriented along the fiber axis. The lower left inset is the FFT of the region outlined by the blue square. The red circles superimposed on the FFT are the predicted indices after choosing the layer spacing along the b direction as The agreement is very good. The lower right inset shows a schematic (not to scale) of goethite layers stacked along the b-axis. The growth direction is along

[200] , coinciding with the bundle axis. The upper left inset is a software-generated SAD pattern where the distance between the bands along the b direction is assumed to be Figure 1 The plane outlined in b is indicated by the red arrow. The upper right inset is a HAADF image of the region shown in the figure. The precursor is TiB 2 , reacted in TMAH at 80 °C for 5 days.

[0010] Figure 4 : Low-angle annular dark-field TEM micrographs of the same sample as shown in Figure 3 . a) Low magnification. b) High magnification of the region enclosed by the green square in a). The scale bar is 5 nm. The zigzag features of Ti atoms in the nanobelts in the region enclosed by the red circle are obvious. Their bilayer nature is also evident.

[0011] Figure 5 : ABF TEM micrographs of the same sample as in Figure 3 , but focused on different regions. The top inset is the FFT generated from the blue square, showing a diffuse ring without distinct diffraction spots. The bottom inset is the FFT obtained from the green square, showing distinct diffraction spots, indicating that this region is mostly crystalline.

[0012] Figure 6 : LAADF TEM image of loose NF bundles from TiC; b) Magnified view of the dashed region in a) shows the crystalline contrast of the NFs. The ordered NF region shows the atomic column contrast of goethite aligned along the

[100] orientation.

[0013] Figure 7 : Tauc plots as a function of various cleaning procedures. (See the Methods section).

[0014] Figure 8 : Scalable synthesis of nanofiber-based mesoporous particles. (a) Schematic of the temperature-controlled shaking incubator used to convert the TiB 2 precursor powder into nanofiber-based mesoporous particles. (b) Following the cleaning protocol to remove any unreacted TMAH salts. (c) DFT-generated goethite structure showing 2-Ti-atom-thick bands growing along

[100] and stacking along

[010] (i.e., the a and b crystal directions, respectively). (d) Insertion of various cations (monovalent and divalent cations) into the inter-filament channels.

[0015] Figure 9 : (a) XRD patterns (logarithmic scale) of the TiB 2 precursor powder (top black curve) and samples reacted for 1 to 5 days, then washed with ethanol and dried overnight in air at 50 °C. The peaks at ≈26°, 48°, and 62° 2θ correspond to the 110, 200, and 002 planes of goethite, respectively. These values correspond to the 3 arcs / rings observed in the SAD pattern of the 1DL in TEM. The 0k0 peak is denoted by an asterisk. The black dashed line represents the diffraction peak of TiB 2 . (b)-(d) SEM micrographs of the mesoporous particles after 5 days of reaction (at different magnifications). The inset in (b) shows the MPP size distribution obtained from the micrograph using ImageJ. Figures 15 - 17 More SEM images are shown.

[0016] Figure 10 : (a) TiB 2 STEM imaging of the mesoparticles of the derived sample, which was oscillated in TMAH at 80 °C for 5 days, washed with ethanol, and then dehydrated in air at 50 °C overnight. (b) and (c) LAADF STEM micrographs of 1DL nanofiber bundles oriented along the fiber axis (at different magnifications). The inset in (b) shows the FFT generated from the area enclosed by the yellow square. (d)-(h) EDX elemental mapping of the mesoparticles shown in the inset of (a).

[0017] Figure 11 : Characterization of mesoporous particles, (a)-(c) XRD patterns and (d)-(k) SEM micrographs, prepared by oscillating the TiB 2 precursor powder in TMAH solution at 80 °C for 5 days, washing with the solvents / solutions marked in the figure, and then drying in air at 50 °C.

[0018] Figure 12 : (a) TiB 2 Zeta potential (left y-axis) and average hydrodynamic size (right y-axis) of the derived sample after oscillating in TMAH at 80 °C for 5 days and then washing with the solvents / solutions marked in the figure.

[0019] Figure 13 : SEM micrographs of the samples at different magnifications after reacting for 1 day (a, b, c) and 5 days (d, e, f). The samples were reacted in TMAH at 80 °C, then washed with ethanol, and then dried in ambient air at 50 °C. Micrographs after reacting for 2, 3, and 4 days are as Figure 25 shown and are indistinguishable from the micrographs shown here.

[0020] Figure 14 : Reaction location and morphology. a) NF forms at the solid / liquid interface by forming TiO 6 octahedra and attaching to the bottom of the growing NF. b) Effect of the washing procedure on the final morphology.

[0021] Figure 15 : SEM micrographs of the samples washed with ethanol and then dried in air at 50 °C overnight at different magnifications. All samples were reacted in an oscillator at 80 °C for 5 days.

[0022] Figure 16 : SEM micrographs of the samples washed with ethanol, then with 0.5 M aqueous LiCl solution, and finally with water, and then dried in air at 50 °C overnight at different magnifications. All samples were reacted in an oscillator at 80 °C for 5 days.

[0023] Figure 17 : SEM micrographs at different magnifications of the samples that were washed with ethanol and then immersed in 5M NaCl aqueous solution and water, and then dried overnight in air at 50 °C. All samples reacted in an oscillator at 80 °C for 5 days.

[0024] Figure 18 : HAADF imaging and EELS elemental mapping of MPP obtained after ethanol washing. (a) HAADF imaging of the NF beam from which the EELS mapping was obtained. (b) HAADF image acquired simultaneously with the elemental mapping. No observable change in morphology was observed in subsequent scans. (c) The elemental composition was collected from the region outlined by the dashed box in (b) and calculated using the Hartree-Slater model. (d)-(g) EELS elemental maps of Ti, O, C, and N, respectively.

[0025] Figure 19 : (a) XRD patterns of the sample before and after ion exchange with the brine solution marked on the figure. (b)-(c) The same as (a), but after ethanol washing, the powder was further treated in LiCl aqueous solution and then stirred in the brine solution marked on the figure. The vertical blue dashed lines are aligned on the figure, representing the d-spacing of the LiCl-washed sample. The vertical black dashed line / grey band represents the lowest and highest d-spacing values of the 110 non-substrate reflection relative to various inserts between the NFs. The vertical red dashed line / band refers to the 200 and 002 goethite reflections at 2θ values of ~48° and 62°, respectively. The asterisk indicates the unreacted TiB 2 peak, which we used as an internal standard to align the XRD patterns.

[0026] Figure 20 : Characterization of mesoporous particles, (a) XRD pattern and (b) SEM micrograph, prepared by oscillating the TiB 2 precursor powder in TMAH solution at 80 °C for 5 days, washing with ethanol until neutral, directly stirring in the solution marked on the figure, and then drying in air at 50 °C. Note the logarithmic scale on the y-axis.

[0027] Figure 21 : (a) and (b) Static frames of the ethanol-washed powder dispersed in ethanol and water, respectively. (c) The same as (a), but the powder was treated in LiCl aqueous solution and then dispersed in water.

[0028] Figure 22. AFM scans of (a) and (b) colloidal suspensions (obtained by heating TiC in TMAH at 80 °C for 3 days, washing with ethanol until neutralized, and then dispersing in water before and after dilution by 500 times respectively, and then drop-casting on glass slides). The inset shows the height profile corresponding to the blue line in (d); the thinnest wire is 1.5 nm high. This figure is reproduced from Mat. Today with permission from Elsevier (license number 5591960829133). F

[0029] Figure 23 . (a) Thermogravimetric plot of MPP prepared by oscillating TiB 2 in TMAH solution at 80 °C for 5 days, and then washing with ethanol until neutralized. Some samples were further treated in LiCl or NaCl solution and then rinsed with water. All powders were dried in air at 50 °C. The vertical dashed lines are 200 °C and 400 °C. (b)-(c) XRD patterns of MPP treated under the conditions marked on the figure. All TGA powders were heated to 800 °C at a rate of 10 °C / min in argon. The black and blue asterisks in (b) and (c) represent anatase and rutile obtained after TGA respectively. The vertical arrow on the middle green line in (c) represents Li2Ti2O4, while the vertical arrow on the bottom red line represents Na 2 Ti 6 O 13 .

[0030] Figure 24 : SEM micrographs of TiB 2 -derived mesoporous particles (washed with ethanol and dried in air at 50 °C) heated to 200 °C under Ar ( Figure 23 represented by the red curve in b). (c)-(f) The same as (a)-(c), but the powder was heated to 800 °C ( Figure 23 represented by the green curve in b).

[0031] Figure 25 : SEM micrographs of the samples at different magnifications after reacting for 2 days (a, b, c), 3 days (d, e, f), and 4 days (g, h, i). The samples were reacted in TMAH at 80 °C, then washed with ethanol, and then dried in ambient air at 50 °C.

[0032] Figure 45: SEM micrograph showing the conversion of TiB 2 particles to 1DL NF by local corrosion. The samples were reacted in TMAH at 80 °C for 3 days, then washed with ethanol, and then dried in ambient air at 50 °C. Detailed Description

[0033] The present disclosure can be more readily understood with reference to the following detailed description of the desired embodiments and the examples included therein.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control. Preferred methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in practice or testing. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting.

[0035] Unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" include plural referents.

[0036] As used in the specification and claims, the term "comprising" can include embodiments of "consisting of" and "consisting essentially of". The terms "comprising", "including", "having", "may", "containing", and their variants as used herein are intended to be open transitional phrases, terms, or words that require the presence of the specified ingredient / step and allow the presence of other ingredients / steps. However, such description should also be construed to describe the composition or method as "consisting of the recited ingredients / steps" and "consisting essentially of the recited ingredients / steps", which allows only the presence of the specified ingredients / steps and any impurities that may result therefrom, and excludes other ingredients / steps.

[0037] As used herein, the terms "about" and "at or about" mean that the quantity or value being discussed can be a value that is approximately or roughly the same as the specified value. It is generally understood that, as used herein, unless otherwise stated or inferred, it is a nominal value ±10% variation. This term is intended to convey that similar values promote equivalent results or effects as described in the claims. That is, it should be understood that quantities, sizes, formulations, parameters, and other amounts and characteristics are not and need not be exact, but can be approximated and / or larger or smaller as needed, reflecting tolerances, conversion factors, rounding, measurement errors, etc., and other factors known to those of ordinary skill in the art. Generally speaking, whether or not explicitly stated, quantities, sizes, formulations, parameters, or other amounts or characteristics are "about" or "approximate". It should be understood that when "about" is used before a quantitative value, the parameter also includes the specific quantitative value itself unless otherwise explicitly stated.

[0038] Unless otherwise stated, numerical values should be understood to include the same numerical values when reduced to the same number of significant figures and numerical values that differ from the stated value by less than the experimental error determined by conventional measurement techniques of the type described in this application.

[0039] All ranges disclosed herein include the endpoints and are independent of the endpoints (e.g., "between 2 grams and 10 grams, and all intermediate values including 2 grams, 10 grams, and all intermediate values"). The endpoints and any values disclosed herein are not limited to the exact ranges or values; they are sufficiently imprecise to include values approximating these ranges and / or values. All ranges are combinable.

[0040] As used herein, approximate language may be used to modify any quantitative representation that can vary without resulting in a change in the basic function associated therewith. Thus, in some cases, a value modified by one or more terms (e.g., "about" and "substantially") may not be limited to the specified exact value. In at least some cases, approximate language may correspond to the precision of the instrument used to measure the value. The modifier "about" should also be considered to disclose a range defined by the absolute values of the two endpoints. For example, the expression "about 2 to about 4" also discloses the range "2 to 4". The term "about" may refer to plus or minus 10% of the indicated number. For example, "about 10%" may represent a range from 9% to 11%, and "about 1" may represent a range from 0.9 to 1.1. Other meanings of "about" may be apparent from the context, such as rounding, and thus, for example, "about 1" may also represent a range from 0.5 to 1.4. Additionally, the term "comprising" should be understood to have an open-ended meaning of "including", but the term also includes the closed-ended meaning of "consisting of". For example, a composition comprising components A and B may be a composition comprising A, B, and other components, but may also be a composition consisting of A and B. Any document cited herein is incorporated herein by reference in its entirety for any purpose.

[0041] Results and Discussion

[0042] All experimental details can be found in the Methods section.

[0043] Figure 1 XRD patterns of 2 samples were plotted on a logarithmic scale. These samples were synthesized by reacting TiB 2 powder with TMAH at 80 °C for 5 days. After the reaction, the resulting powder was washed with ethanol until pH ≈ 7. In one case, the powder was directly dehydrated from ethanol in air at 50 °C ( Figure 1 the bottom blue curve in a). In another case, the precipitate was further stirred in LiCl solution, then rinsed with DI water, and then the powder was allowed to air-dry naturally again ( Figure 1 the top red curve in a).

[0044] Figure 1 The vertical dashed lines in represent two low-intensity unreacted TiB 2The peak serves as an internal standard. When the powder is washed with ethanol, the XRD pattern is characterized by 7 basal reflections with a d-spacing of approximately ≈ This is due to the stacking of "2D" flakes composed of in-plane arrangements of 1DLs (see below). After washing with LiCl (see the method section), the d-spacing value drops to ≈ Confirming that the TMA + cations are replaced by Li + . Figure 1 The yellow bands in a represent goethite non-basal reflections, with values of approximately 26°, 48°, and ≈ These peak positions match very well with our previous XRD patterns and the rings observed in previous SAD patterns in TEM. 12

[0045] Figure 2 The Raman spectra of 6 samples treated in different ways as outlined in the method section are shown. In all cases, the spectra obtained are consistent with goethite. 13 In hindsight, it is now clear that because the laser power used to obtain our previous spectra 12 was too high, causing the transformation of goethite to anatase. The best evidence is that when the laser power is increased, the Raman spectrum changes from a spectrum consistent with goethite to a spectrum consistent with anatase (insert Figure 2 ).

[0046] The next task is to reconcile the XRD pattern ( Figure 1 a) with the goethite structure. This is important because, apart from the (200) peak at ≈ and possibly the peak at ≈ , all other peaks are not standard goethite features. 9,14 The typical features of the latter are a strong (103) peak at ≈ and a smaller (110) peak to its left. 9,14 Recently, Ma et al. 15 published their XRD pattern attributed to goethite, in which 4 peaks were indexed as (101), (004), (200), and there was also a peak at ≈ that they did not index.

[0047] To simulate our structure, we utilized DFT calculations of goethite. 16 The latter consists of bands 2 Ti atoms thick stacked along the b direction ( Figure 1 b). Half of the O atoms are 4-fold coordinated; the other half are 2-fold coordinated. The (200) peak in the XRD pattern is attributed to the plane Figure 1 labeled as the vertical plane in b. As described below, the plane that gives rise to the peak is asFigure 1 as shown in c and indexed as (002). In our coordinate system ( Figure 1 b), ≈ the peak at is attributed to the (110) plane ( Figure 1 b). Most of the other peaks are 00l peaks characteristic of 2D materials. Note that in the ethanol-cleaned samples ( Figure 1 blue pattern in a), the order along the stacking direction is higher than that of the LiCl-cleaned counterparts.

[0048] Figure 3 shows the annular bright-field (ABF) TEM image of the TiB 2 -derived NF bundles, and the FFT at the center of the micrograph outlined by the blue square. To simulate the FFT, we started from the goethite structure generated by DFT 16 and tilted it so that the c-axis became the zone axis ( Figure 1 b). The goethite layers stack along the b-axis ( Figure 1 b), such that the growth direction is

[100] , and importantly, the growth direction coincides with the beam axis ( Figure 3 lower-right inset). The stacking distance between the 2D layers was adjusted to match the (010) and (020) points on the FFT. The selected interlayer distance (hereinafter referred to as d010) is for the other points ( Figure 3 upper-left inset) generated by the single-crystal diffraction module of Crystal Maker software. That is, only one adjustable parameter was used.

[0049] The agreement between the FFT points and our simulated SAD (red circles in the lower-left inset) is very good, indicating that the 110 and 200 d spacings are and The corresponding distances (hereinafter referred to as d110 and d200, respectively) obtained from the XRD patterns of the (110) and (200) planes are and 12 This difference in d-spacing is not unexpected, especially when using the FFT of atomic-resolution STEM images. The position of the "diffraction points" in the FFT is based on the calibration of the underlying STEM image, which is affected by the accuracy of the underlying image calibration, scanning distortion, and image pixel size. The fact that we simulate 2D goethite in DFT while dealing with 1DL in the experiment may play a role. In addition, our material contains C, 12 which is not included in the DFT model, and this fact may be important as we can better understand where the C atoms are located. There is no doubt that the XRD results are more accurate, but the symmetry of the diffraction peaks is consistent. Based on the d200 value, the a lattice parameter is slightly smaller than that of Tominaka et al17 reported They also used TMAH to fabricate 2D lepidocrocite.

[0050] In the bright regions, the Ti atomic columns may stack, as Figure 4 shown, a zigzag pattern of Ti atoms can be discerned, which is consistent with Figure 1 the schematic shown in Figure 1 b.

[0051] Using the Scherer formula, we estimated the domain sizes along

[110] ,

[200] , and

[002] to be 4.2, 7.3, and 3.4 nm, respectively. Compared with the Figure 3 , 4 and micrographs shown in 5, these sizes are smaller, indicating that this order is finer than the relatively large macroscopic features observed (i.e., 2D flakes, fiber bundles, etc.).

[0052] Although the "crystalline" regions are key to our interpretation of the structure, there are indeed a significant number of bundles or 2D flakes with poor crystallinity. Figure 5 Depicts 2 regions surrounded by blue and green squares. The FFT pattern of the blue region ( Figure 5 upper left inset) is clearly amorphous. The corresponding FFT of the green region (lower inset) produces a pattern identical to that Figure 3 shown, but significantly less clear.

[0053] At this point, it is very important to critically evaluate the structure we proposed. Based on DFT calculations, the thickness of the 2-Ti atom band from the outermost O to the outermost O is ≈ ( Figure 1 b). If the total interlayer distance is then the interlayer channel spacing is ≈ Currently, it is not clear why the (0h0) peak clearly visible in the FFT ( Figure 3 ) is missing in the XRD pattern. The origin of all other non-substrate peaks can be traced back to the planes where Ti atoms in one band or unit cell are connected to an increasing number of Ti atoms in adjacent bands ( Figure 1 numbered in Figure 1 b), as shown in

[0054] ≈ The d-spacing of the peak does not match any (1n0) plane ( Figure 1 b), and it does not appear in the Figure 3 simulated FFT shown in the upper left inset. Therefore, it must be associated with the c-axis. The DFT c lattice parameter LP is ≈ Its (002) d-spacing d002 is ≈ In the XRD pattern, experiments show that this peak appears at 61.0 ± 0.4°, 12 corresponding to a c-LP of Therefore, we attribute this crystal peak to the (002) reflection. Note that there are two (002) reflections. The first is related to the stacking of NFs along the c-axis at ( Figure 1 a). The second is crystallographic and originates from Figure 1 the X-rays with top reflections shown in c, which appear at ≈

[0055] Based on the above results, we have determined 2 out of 3 planes of our 1DL NFs; (100) and (001). What about the third surface, i.e., (010)? In this surface, Ti and O atoms are coplanar ( Figure 1 c). If this surface is cut such that only 2 Ti layers remain, they will also project a zigzag pattern ( Figure 1 c), which will be difficult to distinguish from the (001) surface that also produces a zigzag pattern ( Figure 4 ). Despite this comment, from the TEM images shown in Figure 3 and other figures, it can be preliminarily concluded that the thickness of the (001) nanobelts is at ≈ order of magnitude; their DFT width is ( Figure 1 c). If this size is wider, it is less likely to have the relatively uniform microstructure shown in Figure 3 . Equally important, if there are relatively large segments, they will be crystalline and thus easily distinguishable in TEM.

[0056] Similarly, in MXene 18 and other 2D material literatures, it has been confirmed that it is not easy to find "edge-on" oriented multilayers MLs because the substrates of most 2D flakes are parallel to the surface. 19 Generally, most flakes are flipped up at the ML edges to expose their basal planes in an edge-on configuration. 18 The situation here is exactly the opposite; most regions are either poorly crystalline, amorphous, or exhibit an "edge-on" structure ( Figure 3 , 4 and 5). When 2D goethite with a strong (101) peak in XRD is imaged in TEM, it is not difficult to find relatively large islands and lattice fringes. 15,17Their absence strongly suggests that they do not exist and that instead 1DL NFs self-assemble into “2D” sheets. This is important because if the NFs seen here are indeed 1D, then we are dealing with NFs with a cross-sectional area of ≈ In this case, it is important to emphasize that we are not suggesting that 2D layers do not exist; the XRD patterns are clear. What we are saying is that the “2D” sheets are composed of 1DL NFs that self-assemble into layers.

[0057] Figure 6 This further supports the conclusion that we are dealing with NFs. In this TiC-derived sample, individual NFs can be easily discerned. Despite these comments, we acknowledge here that what we see in the micrographs could potentially be the edges of larger sheets extending into the plane of the page, although this is unlikely.

[0058] It is important to verify the above conclusion at this point. Of the three distances d200, d002, and d101, only the first two are crystallographic. For this reason, for all the materials produced to date (over 200 independent runs), the position of the 200 peak at ≈ in the XRD pattern does not change ( Figure 1 a). The same is true for the peak. 12 On the other hand, the position of the (110) peak depends on the surrounding medium ( Figure 1 a), and thus it cannot be crystallographic. Another important observation consistent with this concept is that the distance between NFs in the red line plotted in Figure 3 is ≈ which is comparable to the used to adjust the theory to fit the FFT pattern.

[0059] Compared to 2D materials with one stacking direction, there are two here; one along the (010) direction or the b-axis ( Figure 3 lower right inset in Figure 1 ); the other out of the plane of the page (along the c-axis), which is responsible for the low-angle reflections labeled (00l) in Figure 1 . Not much information about the c-axis spacing or stacking can be gleaned from the STEM images. Not surprisingly, this spacing also varies with the nature of the cations surrounding the NFs, as shown by the peaks labeled (00l) in

[0060] Note that most of the peaks and the strongest peaks are (00l) peaks. This is particularly evident when the y-axis is plotted linearly rather than logarithmically. Figure 7 ) confirm the existence of an indirect bandgap at ≈ 4 eV as previously reported. 12We note in passing that, as discussed in our previous work, 12 This bandgap energy is produced by a bottom-up approach based on TiO 2 The literature contains many reports on TiO-based materials. 2 However, to the best of our knowledge, none of them reported the effect of quantum size on the band gap.

[0061] In summary, TiB was heated in TMAH at 80 °C. 2 The 1D NF produced by reacting TiC powder with lepidocrocite TiO 2 The NFs grow in the

[100] direction and stack along the b direction in the plane. The NFs self-assemble to create bundles ( Figure 3 ) or larger 2D flakes as shown in our previous work. 12 While the "crystalline" regions are key to our understanding of the structure, it is true that a large fraction of the bundles or 2D sheets are poorly crystallized. Some regions appear amorphous.

[0062] No matter how well the NFs self-assemble, if we assume that their cross-section is Their theoretical specific surface area will be >1700m 2 / g. This is an extraordinary number for titanium-containing materials and partly explains some of the extraordinary properties these materials exhibit. The process for making them is inexpensive and highly scalable—we routinely make 100g batches in a laboratory setting—and the precursor powders (such as TiC, TiB 2 The fact that titanium-containing MAX phases) are abundant on Earth and non-toxic suggests that they will be used on a large scale in countless fields.

[0063] method

[0064] Materials synthesis and processing

[0065] The 1DL NF samples were prepared by mixing TiB 2 (Thermo Scientific, -325) powder was mixed with an aqueous solution of tetramethylammonium hydroxide TMAH (Alfa Aesar, 25wt.%, 99.9999% in DI water) at 80°C with a temperature-controlled incubator / oscillator for 5 days. In all cases, the Ti:TMAH molar ratio was kept at 0.6. After the reaction, the resulting powder was washed with ethanol (Decon Lab Inc., 200 degrees) until pH ≈ 7. The powder was then dehydrated in air at 50°C overnight. To explore any potential effects of drying temperature, another sample from the same batch was dehydrated at room temperature (RT).

[0066] To evaluate the ion exchange capacity, the ethanol-washed precipitate was further stirred three times for 6 hours each in one of the following salt solutions in the wet state: 0.5 M LiCl, 5 M LiCl, 0.5 M NaCl, or 5 M NaCl, and then rinsed three times with DI water to remove any unreacted salts or reaction products. All salts were purchased from Alfa Aesar with a purity >99%. The LiCl- and NaCl-washed powders were then air-dried at 50 °C, similar to the above.

[0067] To compare the samples treated with an oscillator and those prepared using magnetic stirring, 20 In one case, TiB 2 powder was magnetically stirred in a TMAH solution at 300 rpm according to the above molar ratio, temperature, and time conditions. After the reaction, the resulting slurry was washed six times with ethanol until the pH ≈ 7, redispersed in DI water, shaken for 5 minutes, and then centrifuged at 3500 rpm for 30 minutes. The resulting colloidal suspension was then filtered using vacuum-assisted filtration to produce a filter membrane, which was air-dried at 50 °C overnight.

[0068] Figure 2 The Raman spectra shown were obtained for the following six samples: ethanol-washed, 0.5 M LiCl, 5 M LiCl, 0.5 M NaCl, 5 M NaCl, and the magnetic stirring sample.

[0069] X-ray diffraction

[0070] XRD patterns were obtained using a diffractometer (Rigaku MiniFlex) operating in the 2 - 65° 2θ range with Cu Kα radiation (40 kV and 15 mA), a step size of 0.02°, and a dwell time of 1 s. All XRD patterns were obtained from powders air-dried at 50 °C overnight.

[0071] Raman spectroscopy

[0072] Two sets of Raman spectra were obtained in two different laboratories. At Drexel University, the Raman spectra were collected in air at room temperature. Measurements were performed using an inverted reflection mode Renishaw InVia (Gloucestershire, UK) instrument equipped with a 63× (NA = 0.7) objective and a diffraction-based room temperature CCD spectrometer. An Ar+ laser (514 nm) was used, and the laser power was maintained in the range of ~0.5 - 1.5 mW.

[0073] In another set obtained from the University of Fayetteville, a suspension of the derivative material QDN with a concentration of 10 mg / mL was prepared using deionized (DI) water (Millipore), isopropyl alcohol (>99.7%, Sigma Aldrich), and dimethyl sulfoxide (DMSO, 99.9%, Sigma Aldrich) solvents, and then drop-cast onto microscope slides and air-dried at room temperature (RT) for 24 hours. Raman spectra were collected at room temperature using an XploRA PLUS confocal Raman microscope (Horiba Scientific, Piscataway, NJ, USA) equipped with a 250 mm focal length spectrometer in a backscattering geometry. The spectrometer was first calibrated using a silicon chip, excited by an air-cooled 532 nm solid-state laser (100 mW), and a spot size of 1 μm was obtained using a 100x (NA = 0.9 and WD = 0.21 mm) objective. A 1200 gr / mm grating was used, and scattered light was collected using a thermoelectric (TE) air-cooled charge-coupled device (CCD) detector with 1024 x 256 pixels and a spectral resolution of 1 cm 2 -1. The laser power was attenuated to 10%, 25%, 50%, or 100% using a neutral density (ND) filter wheel, and spectra were acquired at lower power (10%) or higher power. Raman spectra were collected in the range of 75–1200 cm -1 -1 with an integration time of 2 seconds and a cumulative number of 64 times. The collected Raman spectra were fitted according to the Gaussian-Lorentzian function using LabSpec 6 software to obtain the peak positions and their intensities. -1

[0074] Transmission electron microscopy

[0075] Atomic-scale characterization was performed using an aberration-corrected cold field emission TEM (JEOL ARM200CF) operating at a primary electron energy of 200 kV. 21 Imaging was performed with an emission current of 15 μA and an electron probe semi-convergence angle of 24 mrad, resulting in an electron probe size of approximately 80 pm. Annular bright field (ABF) imaging 22-23 is a coherent imaging technique that uses an outer angle of 23 mrad and an inner angle of 11 mrad for imaging. For low-angle annular dark field (LAADF) imaging, the inner and outer angles are 30 mrad and 120 mrad, respectively. HAADF images 24 were collected with inner and outer detector angles of 68 mrad and 280 mrad, respectively. The main contrast mechanism for HAADF imaging is related to the square of the average atomic number and the total thickness of the atomic columns. 25

[0076] The TEM samples were prepared by dispersing nanofiber powder in 5 mL of methanol. The solution was drop-cast onto a 3 mm copper grid coated with a lacey carbon film and allowed to dry for one hour. Then the TEM grid was loaded onto a plasma-cleaned double-tilt holder and inserted into the microscope column.

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[0103] Additional disclosure – II

[0104] Titanium dioxide (TiO 2 ) nanostructures have become and will continue to be the subject of extensive research attention due to their unique physical and chemical properties and potential applications in numerous fields such as paint pigments, catalysis, photocatalysis, photoluminescence, gas sensors, solar energy, and fuel cells. Among commercially available nanostructured titanium dioxides, Evonik's Aeroxide TiO 2 P25 (previously sold by Degussa), hereinafter referred to as P25, is used. P25 synthesized by the flame pyrolysis of TiCl 4 is attractive due to its high photocatalytic activity.

[0105] In many respects, P25 has been and still is considered the gold standard for TiO 2 -based catalytic and photocatalytic applications. However, its main drawback is cost; flame pyrolysis is a relatively expensive process. It can be said that if P25 were cheaper, it would find more applications. Therefore, we have developed a significantly cheaper method for fabricating one-dimensional (1D) titanium dioxide, which we have shown to perform better than P25 in many applications.

[0106] The formulation requires reacting a precursor powder with an aqueous solution of tetramethylammonium hydroxide (TMAH) (in a polyethylene bottle) at a temperature range of 50 °C to 85 °C for several days. In one case, we used 5 different Mn-containing powders (such as Mn 3 O 4 , Mn 2 O 3, MnB, etc.) react in an aqueous TMAH solution for several days and are converted into birnessite-based two-dimensional (2D) sheets with a thickness of 2 ± 0.4 nm and a width of ≈200 nm. These 2D birnessite sheets have remarkable crystallinity. In turn, they exhibit enhanced electrochemical reactivity in both reversible O 2 electrocatalysis and supercapacitor applications.

[0107] Following the same protocol, immersing FeB powder in an alkaline aqueous solution (TMAH; tetramethylammonium hydroxide, TBAH; or potassium hydroxide, KOH) produces ferromagnetic Fe 3 O 4 nanoparticles with an average particle size of ∼15 nm.

[0108] In another example, we convert inexpensive, earth-abundant, water-insoluble Ti precursors (including TiC, TiN, TiB 2 , etc.) into 1D nanowires (NFs). The recipe requires reacting the Ti precursor powder with an aqueous TMAH solution (in a polyethylene bottle) for several days in the temperature range of 50 °C to 85 °C. We conclude that the 1D NFs crystallize in a goethite-type TiO 2 -based structure ( Figure 8 c). Henceforth, these goethite 1D NFs will be referred to as 1DLs. The cross-sectional area of our 1DL NFs is ≈ This extreme size leads us to conclude that for bottom-up processed titanium dioxide-based materials, the quantum size effect is responsible for the record bandgap energy (E g ≈ 4 eV).

[0109] We have conducted several studies on our 1DLs, and the results show that they are unique and outperform P25. We show that when exposed to radiation equivalent to one sun, the photochemical hydrogen production rate is approximately an order of magnitude higher than that of P25 tested under the same conditions. In the field of water purification, we show that our 1DLs can adsorb record amounts of uranium (U 4+ ) values, making water contaminated with this actinide drinkable. Finally, compared to the original polymer, the composite of our 1DLs with a repairable dynamic covalent thiol network shows a 500-fold increase in modulus at 60 wt% filler.

[0110] After the reaction, it was washed with ethanol (EtOH) until the pH ≈ 7, then washed with water, and pseudo-two-dimensional p-2D was formed after filtration. We call them "pseudo" because the flakes (composed of 1DL NF) are only superficially 2D. We show that these p-2D flakes exist in the colloid even at relatively short reaction times. It can be seen that water exerts a strong driving force to align the 1DL perpendicular to its

[200] growth direction. This self-alignment first leads to the formation of nanobundles and μ-fibers, which in turn self-align into p-2D flakes. Regardless of the experimental conditions or the final morphology, the 1DL NF remains an essential building block.

[0111] Here, we show that if the 1DL NF is dried in ethanol (i.e., not dispersed in water), they form spherical mesoporous particles, hereinafter referred to as MPP, with a diameter comparable to that of the precursor powder. In this work, we: i) report the large-scale synthesis (100 g batch) of MPP composed of 1DLNF; ii) elucidate the mechanism leading to the formation of MPP; iii) show that, like other layered titanates, the space between the NF is highly ion-exchangeable. To this end, we can easily replace the TMA + , Li + , Na + , Mg 2+ , Mn 2+ , Fe 2+ , Ni 2+ , Co 2+ or Zn 2+ cations present after the reaction stage with the TMA + cations (see the schematic diagram in Figure 8 d). iv) Measure the surface charge and hydrodynamic radius of the MPP inserted with TMA + or Li + ions.

[0112] The starting precursor selected was TiB 2 , because it is the most reactive compared to TiC and TiN. A large batch of TiB 2 powder can be almost completely converted to 1DL at 80 °C in ≈ 3 days.

[0113] Results and Discussion

[0114] The precursor was reacted with TMAH using a hot plate and a magnetic stirrer. To prepare batches of up to 100 g at a time, we used a temperature-controlled shaking incubator. The experimental details can be found in the experimental procedure section. Briefly, we mixed 100 g of commercially available TiB 2 powder with ∼1 L of 25 wt.% TMAH aqueous solution and shook it in a temperature-controlled shaking incubator at 80 °C for 1 to 5 days (d) ( Figure 8a). In a set of experiments, the resulting powder was washed several times with EtOH using a overhead stirrer until the pH was ~7( Figure 8 b), and then it was placed in air to dry at 50 °C.

[0115] Preliminary results showed that when the EtOH-washed samples were put into water, the MPP did not maintain its morphology. However, if the TMA + cation was replaced by Li + cation, the MPP would maintain its morphology. To explore this idea, in a set of experiments, the EtOH-washed powder was stirred in saline solutions of 0.5 M LiCl, 5 M LiCl, 0.5 M NaCl or 5 M NaCl in the wet state( Figure 9 d). Then the powder was rinsed several times with DI water to remove any residual salts and then dried in air at 50 °C.

[0116] To evaluate the ability to insert various monovalent and divalent cations between the NFs, the EtOH- and EtOH / LiCl-washed powders were further treated by placing them in one of the following aqueous solutions( Figure 8 d): i) 0.1 M nitric acid, HNO 3 , 0.5 M acetic acid or ii) an aqueous solution of one of the following salts at 0.02 M: MgCl 2 , MnCl 2 , FeSO 4 , CoCl 2 , NiCl 2 or ZnCl 2 . In all cases, after the powder was immersed in the salt solution, it was washed several times with DI water and dried in air at 50 °C for 24 h.

[0117] Characterization of 1DL NFs

[0118] Before going further, the X-ray diffraction (XRD) characteristics of our 1DL NFs can be viewed. Figure 9 a shows the reaction time dependence (on a logarithmic scale) of the XRD pattern. In a typical 1DL XRD pattern( Figure 9 a), there are three types of peaks. The first is due to the unreacted precursor (in this case TiB 2 ), at Figure 9They are shown as black dashed lines in a. They are useful because they can be used as internal standards. Second, the 010 peak at low 2q angles - and its higher 0k0 reflections (indicated by asterisks) - reflect the d-spacing values between NFs stacked along the b direction. As with other 2D materials, the positions of these peaks are strongly related to the cations inserted between them. Importantly, the distance here is not the distance between the flakes, but the distance between the NFs. According to Figure 9 the results shown in a, it is clear that after the first day, the d-spacing is no longer a function of the reaction time.

[0119] The (110) peak located at approximately ~26° 2q ( Figure 9 shown as a gray band in a) is a weak function of the cations between the NFs. The last and most fundamental peaks are the peaks at 2q values of approximately ~48° and 62° - Figure 9 shown as red bands in a - indexed as 200 and 002 of the goethite structure, respectively. These peaks are useful because they are essentially crystallographic and should - as confirmed in this article - be completely independent of the cations in the system. It is from these 2q values that we obtained the a and c lattice parameters of goethite, namely and

[0120] As mentioned above, Figure 9 a shows the time dependence of the XRD patterns of the TiB 2 precursor powder ( Figure 9 the top pattern in a) and the powders reacted at 80 °C for 1 to 5 days, as Figure 9 shown from top to bottom in a. As the reaction time increased from 1 day to 3 days, the intensity of the TiB 2 diffraction peaks gradually decreased, while the 1DL peak became dominant. The latter was again identified by Figure 9 the two red bands in a and the low-angle 010 peak (and its higher-order peaks) at 9° 2q. The distance between the 1DL NFs was calculated to be These results indicate that after 3 days, the conversion of the precursor to the 1DL powder was complete. However, to minimize the proportion of unreacted precursor, we carried out a 5-day reaction. All characterizations were performed on the powder reacted for 5 days ( Figure 9 the blue curve in a).

[0121] Figure 9 b - d show the scanning electron microscope (SEM) micrographs of a typical MPP after cleaning with EtOH to pH 7. On the millimeter scale, the powder appears to be well-dispersed and little aggregation was observed ( Figure 9 b). At higher magnification, the MPP is porous and mostly spherical, with an average size of ~13 μm ( Figure 9inset in b), consisting of entangled 1DL NF bundles ( Figure 9 c and d). To date, in 50 different batches prepared and characterized, the shape and size of the MPPs have been very consistent. Other micrographs are shown as Figures 15 - 17 follows. Summarizing this section: After cleaning with EtOH, the 1DL NF self-assembles into individual, non-agglomerated, free-flowing MPPs with a particle size range of 5 to 30 μm ( Figure 2 b and inset).

[0122] To better understand the MPP structure, we imaged it in HR-STEM ( Figure 10 a-c). If we assume that the fiber bundle shown in Figure 10 a is a single MPP, its diameter is approximately 1 μm. At higher magnification, it is clear that the bundle is again composed of multiple 1DL NF ( Figure 10 b and c). Low-angle annular dark field (LAADF) images ( Figure 10 c) show that the building blocks are still NF, 2 Ti atoms wide, with a zigzag pattern. The fast Fourier transform (FFT) pattern of the bundle ( Figure 10 inset in b) yields 2 main arcs - confirming the 1D nature of our NF - with d-spacings corresponding to the XRD peaks at 2θ values of ∼26° and ∼48° ( Figure 9 gray and red dashed bands in a). Additionally, the arcs bisect the

[100] growth direction.

[0123] Regarding the composition of the 1DL bundles, we obtained STEM-EDS maps of the MPPs shown in Figure 10 the inset in a. Only trace amounts of B (<1%) were detected ( Figure 10 d), which is consistent with the almost complete conversion of TiB 2 to 1DL NF and the effectiveness of our process in washing out any B-containing reaction products. From an extended perspective, these powders were neither centrifuged nor filtered. Note the uniform distribution of Ti and O atoms ( Figure 10 e-f). The calculated atomic percentages of Ti and O are 24.5% and 49.5% respectively, which is consistent with the TiO 2 stoichiometry. Lacy carbon carriers can be seen in the C map ( Figure 10 g), which obscures the C in the 1DL. The uniform distribution of N on the MPP supports the fact that TMA + ions are inserted between the NF ( Figure 10 h). Due to the large overlap between the N K-edge and the Ti L-edge, it is difficult to quantify the amount of N present.

[0124] To address this issue and better control the C content, we acquired electron energy loss spectroscopy (EELS) spectra in which the Ti and N peaks are easily distinguishable, and the elemental composition can be calculated using the Hartree-Slater cross-section model. To further reduce the contribution of surface hydrocarbons, we used a liquid nitrogen N 2 cold stage to cool the sample in situ. Elemental mapping derived from the core loss spectra ( Figure 18 ) shows that the Ti and O concentrations are again consistent with the TiO 2 stoichiometry. The ratio of C to N is 4.5, which is consistent with the expected ratio of 4 for the TMA cation.

[0125] Chemical stability and cation exchange of 1DL NF

[0126] We determined that we could easily ion-exchange the TMA + cation (present after EtOH washing to pH ≈ 7). Here we show that the Li + cation can in turn be replaced by the following cations: H + , Na + , Mg + , Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , and Zn 2 + . The XRD patterns after ion exchange are plotted in 2+ . Typical SEM micrographs of the MPP are shown in Figure 11 a-c. Figure 11 d-k. Figure 19 a-c show the same data as shown in Figure 11 a-c, but on a logarithmic scale.

[0127] As described in the experimental section, after ion exchange, all powders were rinsed several times with DI water and dried in air at 50 °C before further characterization. In all cases, no other peaks were observed except for the 1DL XRD peaks ( Figure 11 a-c and 19a-c), which confirmed that we had successfully removed most of the unreacted salts and unwanted reaction products. This also means that the unwanted reaction products are water-soluble.

[0128] After EtOH washing ( Figure 11 the blue patterns in c and 19a), the first peak is at ∼7.5° 2θ, corresponding to the 010 basal reflection, whose d-spacing is a measure of the thickness of the NF along the b direction as well as any intercalated ions and / or water. Since we know from DFT calculations that the thickness of one NF along the b direction is ≈ Therefore, TMA + and H 2 O thickness is ≈ This is reasonable.

[0129] After cleaning with LiCl or NaCl solution ([[]] Figure 11 black and green patterns in a and 19a respectively), the d-spacing shrinks to and confirming that TMA + ions are successfully exchanged with Li + or Na + ions. The d-spacing of the Li + -inserted powder is slightly higher than that of Na + , which may reflect a slightly larger hydration shell for the former (see Figure 23 for the TGA results). Similarly, assuming the thickness of one NF along the b-direction is ≈ then the Li + +H 2 O and Na + +H 2 O thicknesses are and

[0130] Figure 11 b shows the XRD patterns of the powder first cleaned with LiCl solution and then treated in HNO 3 or MgCl 2 aqueous solution. The XRD patterns of the remaining cations are plotted in Figure 11 c. For the Li + -inserted NF, the initial d-spacing is ≈ ( Figure 11 top black pattern in b and c). When stirred in 0.1 M nitric acid, the peak slightly shifts to ≈ ( Figure 11 red pattern in b), indicating that hydronium ions have been successfully inserted between the NFs. Similarly, stirring the Li 2 -inserted NF in 0.02 M MgCl + solution ( Figure 11 green pattern in b) causes the d-spacing to expand from to which we take as evidence of the exchange of Li + ions with Mg 2+ ions.

[0131] Other divalent cations (Mn 2+ 、Fe 2+The situation is very similar to that of (etc.). When the LiCl-washed powder is further treated in an aqueous solution of 0.02 M target cations, Li + and Mn 2+ 、Fe 2+ 、Co 2+ 、Ni 2+ and Zn 2+ cation exchange occurs between them. As Figure 11 shown in c, for Mn 2+ 、Fe 2+ 、Co 2+ 、Ni 2+ and Zn 2+ inserted into 1DL NF, the d-spacings obtained after cation exchange are and

[0132] Interestingly, when the powder washed with EtOH is directly (i.e., without first exchanging TMA + with Li + ) immersed in HNO 3 、CoCl 2 or NiCl 2 aqueous solution for 24 hours or longer, the low-angle peak disappears ( Figure 20 a), which means that any order along the b stacking direction is disrupted. The only remaining peaks are the three non-substrate reflections at 2θ values of ≈26°, ≈48° and ≈62° ( Figure 20 the red bands in a). The SEM micrograph of the NiCl 2 washed sample ( Figure 20 b) confirms the change in the MPP morphology to nano-sized, slightly porous aggregates.

[0133] To summarize this section, the inter-filament space between 1DL NF is easily exchangeable with monovalent (H3O + 、Li + and Na + ) and divalent cations (Mg 2+ 、Mn 2+ 、Fe 2+ 、Co 2+ 、Ni 2+ and Zn 2+ ). Through the slight shift of the small-angle (<10°) 2θ peak, the corresponding XRD patterns clearly show the successful insertion of these cations. It can be noted here that the non-substrate peaks located at ~48° and 62° 2θ ( Figure 11 the red dotted lines / bands in a-c and 19a-c) are perfectly aligned in all cases, regardless of the nature of the insert. This result indirectly confirms the correctness of assigning these peaks to the 1DL backbone (see below).

[0134] Surface Charge and Hydrodynamic Size of NF Aggregates

[0135] One goal of this work was to investigate the surface charge and aggregation behavior of the prepared NF and NF-based MPPs doped with TMA + or Li + cations. To this end, we measured the zeta potential ζ and the hydrodynamic diameter d of the powders once after cleaning with EtOH and another time after cleaning with an aqueous LiCl solution H . Note that except for the first sample (top row in Table 1) which was cleaned and measured in EtOH, all other samples were cleaned with the solvents / solutions mentioned in the first column of Table 1 and then dispersed in DI water to measure the ζ potential and d H . All measurements were repeated 3 times; the average of the results was taken (see Figure 12 ) and summarized in Table 1 below

[0136] Table 1: Summary of the measured ζ potential and Z-average hydrodynamic size d H as a function of the cleaning media shown in the left column

[0137]

[0138] When the solvent was EtOH, the ζ potential of the MPP was -5 ± 1.5 mV, which explains the colloidal instability in this solvent; the MPP settled to the bottom of the container ( Figure 21 a), and only particles / entities with d H of ~0.1 μm remained suspended (right axis in Figure 12 ). When the MPP was dispersed in DI water, the recorded ζ potential was approximately ~ -53 ± 10 mV, resulting in a highly stable colloidal suspension (see Figure 21 b). The high surface charge stabilized the aggregates of 1DL NF to a size of 2 ± 0.8 μm (right axis in Figure 12 ). The size of these aggregates is a function of the colloidal concentration. After cleaning the MPP with an aqueous LiCl solution (immediately after cleaning with EtOH), the ζ potential value decreased from -53 ± 10 mV in DI water to -33 ± 1.3 mV in a 0.05 M LiCl solution ( Figure 12 and Table 1). As the molar concentration of the LiCl solution increased to 0.5 M and 5 M, the ζ potential changed slightly to ≈ -28 ± 0.5 mV ( Figure 12 and Table 1 above

[0139] When the MPP (cleaned with ethanol to neutrality) was dried at 50 °C and then redispersed in DI water, the pH increased significantly to a value of ~10. This may be due to O - and / or OH -This is due to the absorption of protons at the surface end. However, in our case, we did not observe any change in the low-angle peak, indicating that the surface oxygen atoms were hydroxylated by protonation.

[0140] In summary, after neutralization in EtOH, the ζ-potential was slightly negative and most of the MPP settled ( Figure 21 c). Only aggregates smaller than 1.4 μm were suspended in EtOH ( Figure 12 ). After washing with water, the ζ-potential was very negative at ≈ -50 ± 10 mV, which explained the colloidal stability in water.

[0141] From DI water to 0.05 M LiCl solution, the surface charge decreased significantly, which basically corresponded to the electrostatic adsorption of Li + ions on the negatively charged surface of NF. This in turn led to a reduction in the electric double layer, resulting in a decrease in the repulsive electrostatic interaction between NFs. As the molar concentration increased from 0.05 M to 5 M, the surface charge then decreased ( Figure 12 and Table 1), which further demonstrated that the diffusion layer thickness of 1DL NF decreased with increasing ionic strength.

[0142] Thermal stability of 1DL NF

[0143] The thermal stability of our MPP was investigated by thermogravimetric analysis (TGA) of NFs inserted with TMA + , Li + or Na + in Ar up to 800 °C. Before the TGA experiment, all powders were dried in air at 50 °C for 24 h. The TGA results of the samples washed with ethanol and salt were different. Figure 23 a. The latter lost weight before ≈ 250 °C and then leveled off. The weight change at this temperature was mainly due to the loss of H 2 O. 26 The weight loss caused by washing with LiCl was slightly higher (18%) than that with NaCl (15%) ( Figure 23 a).

[0144] Heating the NF washed with EtOH and inserted with TMA + to 200 °C resulted in a mass loss of ≈ 15%, which was mainly probably due to the residual EtOH solvent during washing ( Figure 23 a). Further heating to ≈ 350 °C led to a further mass decrease of ≈ 15%, which was most likely due to the loss of the hydration layer between NFs and the inserted TMA cations ( Figure 23 a). Heating to 200 °C did not change the XRD pattern ( Figure 23 b). At higher magnification ( Figure 24f), some NFs start to spheroidize / coarsen.

[0145] Heating the LiCl-washed MPP at up to ≈200 °C results in a primary mass loss event of ≈17 wt.% ( Figure 23 a), which most likely corresponds to the loss of the hydration layer associated with Li cations and / or dehydroxylation. The situation for the NaCl-washed MPP is very similar, with a mass loss of approximately 14 wt.% observed at up to ≈200 °C ( Figure 23 a). The higher mass loss (17%) for the LiCl-washed sample indicates that the number of water molecules associated with Li ions is slightly higher than that of Na ions (with a weight loss of ≈15%). When the powder is further heated to 800 °C, no further weight loss is observed.

[0146] However, the XRD patterns show that the Li + -inserted NFs transform into a mixture of rutile and lithium titanate, Li 2 Ti 2 O 4 ( Figure 23 green pattern in c). After calcination at 800 °C, the Na + -inserted NFs transform into a mixture of rutile and sodium titanate, Na 2 Ti 6 O 13 .

[0147] 1DL NF Morphology, Formation Mechanism, and Self-Assembly

[0148] The Location and Nature of the Reaction Occurrence

[0149] Here, Figure 9 the XRD patterns of the samples reacted for 1 to 5 days as shown in a clearly show the presence of strong TiB 2 peaks ( Figure 9 black dashed lines in a). The corresponding SEM micrographs ( Figure 13 and Figure 25 ) clearly show that, regardless of the reaction time, the surface of the MPP looks the same at all magnifications. This is a useful observation as it indicates that the transformation of TiB 2 to 1DL starts from the surface and moves inwards towards the central core over time. This also indicates that, at least initially, the reaction must be surface reaction rate-controlled (see Figure 26 ). Figure 14 a is a schematic diagram of what we imagine is happening at the interface. First, Ti atoms are released into the reaction medium, at which point they are transformed into TiO 6Octahedron. The latter then inserts itself between the receding substrate and the 1DL growing away from it. The implications of this conclusion are useful because in principle it allows for the formation of core-shell configurations.

[0150] One of the major drawbacks of using nanomaterials, especially nanoparticles, is that often after expending a great deal of effort in fabricating them, they aggregate and require additional processing to disperse them, which in turn introduces unwanted chemicals and contaminants. Thus, the fact that our MPPs are free-flowing can be revolutionary because we can now have many of the advantages of reduced size without their disadvantages.

[0151] Finally, the fact that NF nucleates on the surface of our precursors may also explain why these 1DL NFs have not been found previously. In most sol-gel work to date, the starting point has been water-soluble Ti sources. We speculate that nucleation of the reaction on a solid surface allows the NF to grow in only one dimension. More work needs to be done here. However, there is no doubt that this form of Ostwald ripening is occurring in our microstructures. Our initial TiB 2 had a primary particle size in the range of 5 μm, with a few particles exceeding 10 μm in size. As Figure 9 shown in the inset in b, the final size of the MPPs is larger. This result not only confirms the Ostwald ripening mechanism but also indicates that our final product, 1DL NFs, can dissolve and reprecipitate in our reaction medium.

[0152] In summary, we report a truly large-scale synthesis method for TiO 2 -based sub-nanostructures using a facile solution precipitation method at ambient pressure and temperatures <100 °C. Our method requires shaking water-insoluble, inexpensive, and commercially available Ti-containing powders (such as TiB 2 ) in an aqueous solution of TMAH in a plastic bottle at 80 °C for 1 - 5 days. The resulting powder is washed with EtOH and water using a overhead stirrer and beaker, and then allowed to dehydrate in air at 50 °C. Centrifugation or filtration is not required when handling these nanomaterials, thus reducing the production cost at an industrial level. Low-magnification SEM imaging shows that each particle has a spongy morphology with an average size of ∼13 μm. Further detailed by using HR-STEM and SAD patterns, the building blocks of the MPPs are goethite-type titanate NFs with a cross-sectional area of and lengths of several micrometers. According to our TGA results, the mesoporous morphology remains stable up to a temperature of 800 °C.

[0153] We further investigated the ability to insert various cations into the inter-filament channels. Here, we show that the NFs can interact with various monovalent cations (H 3 O+ , Li + and Na + ) and divalent cations (Mg 2+ , Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ and Zn 2+ ) can easily undergo ion exchange.

[0154] Finally, we investigated the surface charge and hydrodynamic size of the self-assembled NFs and showed that the ζ potential can be > -60 mV in DI water, resulting in a highly stable colloidal suspension.

[0155] Experimental procedures

[0156] Material synthesis and processing

[0157] 1DL sample preparation

[0158] Our scalable synthesis protocol requires mixing commercial TiB 2 (-325 mesh, Thermo Scientific, Pennsylvania, USA) powder with an aqueous TMAH solution (Alfa Aesar, 25 wt.% in DI water, 99.9999%) in a polyethylene bottle. The Ti:TMAH molar ratio was kept constant at 0.6. In a typical batch, we immersed 100 g of TiB 2 powder into 900 mL of TMAH solution in 5 different polyethylene bottles, each with a capacity of 250 mL. The bottles were then transferred to a temperature-controlled incubator / shaker (211DS 49L orbital shaker, Labnet International Inc., North Carolina) and shaken at 175 rpm at 80 °C for 1 to 5 days.

[0159] Washing protocol

[0160] After the reaction, all the resulting precipitates were combined in a 1 L beaker, allowed the powder to settle, then the supernatant was poured out and discarded. To wash away any unreacted TMAH, the 1 L beaker was refilled with EtOH (Decon Lab Inc., 200 proof), stirred for 1 to 2 hours at room temperature using a overhead stirrer (OSC-10L-200 rpm, LabFish, China), then allowed the powder to settle again, and the EtOH supernatant containing excess TMA + cations and other unwanted reaction products was poured into the waste again. This process was repeated several times until the pH was ≈ 7, and then the powder was dried overnight in air at 50 °C.

[0161] Synthesis of ion-inserted 1DL NFs

[0162] To evaluate the ion exchange capacity, some powders were then further stirred 3 times for 6 hours each on a magnetic stirrer in one of the following salt solutions in the wet state: 0.5 M LiCl, 5 M LiCl, 0.5 M NaCl, or 5 M NaCl, and then rinsed 3 times with DI water to remove any unreacted salts and / or reaction products. All salts were purchased from Alfa Aesar with a purity >99%. The LiCl- and NaCl-treated powders were then air-dried overnight at 50 °C.

[0163] X-ray diffraction, XRD

[0164] XRD patterns were obtained using a diffractometer (Rigaku MiniFlex, Tokyo, Japan) operating with Cu Kα radiation (40 kV and 15 mA). The powders were scanned in the range of 2 - 65° 2θ with a step size of 0.02° and a dwell time of 1 s. Unless otherwise stated, all powders were dried overnight in air at 50 °C before any XRD scans.

[0165] Scanning electron microscopy

[0166] Micrographs of our materials were obtained using a scanning electron microscope SEM (Zeiss Supra 50VP, Carl Zeiss SMT AG, Oberkochen, Germany). The SEM settings were set to an in-lens detector, a 30 mm aperture, and an acceleration voltage of 3 - 5 kV.

[0167] Particle size distribution

[0168] The particle size distribution was performed by measuring the minimum and maximum lengths of each of a total of 100 particles using ImageJ software.

[0169] Scanning transmission electron microscopy

[0170] Scanning transmission electron microscopy STEM was performed using an aberration-corrected cold field emission JEOL ARM200CF, operating at a primary electron energy of 200 kV. Imaging and spectroscopic measurements were carried out at an emission current of 15 μA, an electron probe semi-convergence angle of 24 mrad, and inner and outer detector angles of 68 mrad and 280 mrad for high-angle annular dark field (HAADF) imaging. For low-angle annular dark field (LAADF) imaging, the inner and outer angles were 30 mrad and 120 mrad, respectively. Annular bright field (ABF) imaging was performed using an outer angle of 23 mrad and an inner angle of 11 mrad.

[0171] For nano-scale elemental identification and quantification, the ARM200CF is equipped with an Oxford XMX100TLE X-ray windowless silicon drift detector (SDD) with a detector area of 100 mm 2 .

[0172] STEM samples were prepared by drop-casting a suspension of 5 ml of TiB 2 derived powder (5d, 80 °C) in mEtOH onto a 3 mm lacey carbon copper grid. The samples were then allowed to dry for one hour and then inserted into the microscope column.

[0173] Electron energy loss spectroscopy (EELS)

[0174] EELS measurements were performed using a post-column Gatan Continuum GIFER spectrometer with an electron probe semi-convergence angle of 17.8 mrad and a collection angle of 53.4 mrad. In-situ cooling was performed using a Gatan 636 liquid nitrogen N 2 cold stage. To reduce the presence of diving, the sample was heated to 100 °C inside the microscope column and held for one hour.

[0175] Zeta potential and particle size measurements

[0176] A Zetasizer (Nano-ZS, Malvern Panalytical, Malvern, UK) was used for electrophoretic mobility measurements. The electrophoretic mobility values were converted to zeta potential ζ using the Smoluchowski model. The hydrodynamic diameter d was also measured using dynamic light scattering DLS on the same machine H . The average hydrodynamic diameter was calculated from the diffusion coefficient using the Strokes-Einstein equation. All measurements were performed under ambient conditions with an equilibration time of 120 seconds.

[0177] Thermogravimetric analysis, TGA

[0178] A thermogravimetric balance (TA Instruments Q50, Newcastle, Delaware, USA) was used for TGA analysis. Dry powder (∼40 mg) was loaded into a sapphire crucible and heated at a rate of 10 °C / minute to 800 °C under an Ar flow of 10 mL / minute, and then the system was allowed to cool naturally.

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[0227] Aspect

[0228] The following aspects are illustrative only and do not limit the scope of the present disclosure or the claims. Any one or more parts of any one or more aspects may be combined with any one or more parts of any one or more other aspects.

[0229] Aspect 1. A composition comprising: a plurality of metal oxide sub-nanowires and / or nanowires, said sub-nanowires and / or nanowires optionally comprising goethite regions, said plurality of metal oxide sub-nanowires and / or nanowires optionally comprising a certain amount of carbon, said plurality of metal oxide sub-nanowires and / or nanowires optionally being in bundles, sheets, or both sheets and bundles.

[0230] Aspect 2. The composition according to claim 1, wherein at least some of said nanowires and / or sub-nanowires have a width in the range of about to about such as about to about .

[0231] Aspect 3. The composition of Aspect 1, wherein at least some of the nanofibers and / or sub-nanofibers contain Ti atoms. The Ti atoms can be arranged, for example, in a zigzag pattern.

[0232] Aspect 4. The composition of Aspect 1, wherein the nanofibers and / or sub-nanofibers define a non-circular cross-section. Such a cross-section can be, for example, elliptical.

[0233] Aspect 5. The composition of Aspect 4, wherein the nanofibers and / or sub-nanofibers define a cross-sectional aspect ratio greater than 1 to about 10.

[0234] Aspect 6. The composition of Aspect 5, wherein the nanofibers and / or sub-nanofibers define a cross-sectional aspect ratio of about 2 to about 5.

[0235] Aspect 7. The composition of Aspect 1, wherein the average cross-sectional area of the nanofibers and / or sub-nanofibers is in the range of about to about .

[0236] Aspect 8. The composition of Aspect 1, wherein the length of at least some of the nanofibers and / or sub-nanofibers is in the range of 1 nm to about 25 μm.

[0237] Aspect 9. The composition of Aspect 8, wherein the length of at least some of the nanofibers and / or sub-nanofibers is in the range of 1 nm to about 1 μm.

[0238] Aspect 10. The composition of Aspect 1, wherein the nanofibers and / or sub-nanofibers are contained in a plurality of sheets.

[0239] Aspect 11. The composition of Aspect 1, wherein at least some of the plurality of nanofibers and / or sub-nanofibers are located in a common plane.

[0240] Aspect 12. The composition of any one of Aspects 1-11, further comprising a pharmaceutically acceptable carrier.

[0241] Aspect 13. The composition of Aspect 1, further comprising an adhesive.

[0242] Aspect 14. The composition of Aspect 13, wherein the adhesive comprises a polymer.

[0243] Aspect 15. A device comprising the composition according to Aspect 1.

[0244] Aspect 16. The device of Aspect 15, wherein the device is characterized as an energy storage device.

[0245] Aspect 17. The device of Aspect 15, wherein the device comprises an electrode.

[0246] Aspect 18. The device of aspect 17, wherein the electrode comprises the composition according to aspect 1.

[0247] Aspect 19. The device of aspect 15, wherein the device comprises a dispenser in which the composition according to aspect 1 is provided.

[0248] Aspect 20. A method comprising contacting a mono-, bi-, tri- or higher-valent carbide, nitride, boride, phosphide, aluminate or silicide or titanium metal with a quaternary ammonium salt and / or a base, wherein the mono-, bi-, tri- or higher-valent carbide, nitride, boride, phosphide, aluminate or silicide or titanium metal is optionally water-insoluble, and the water-insoluble bi-, tri- or higher-valent carbide, nitride, boride, phosphide, aluminate or silicide optionally comprises a transition metal, and the transition metal optionally comprises titanium, and the contacting is carried out under conditions sufficient to produce a nanofibrous product.

[0249] Aspect 21. The method of aspect 20, wherein the conditions include a temperature of 0 °C to 100 °C for about 5 hours to about 1 week.

[0250] Aspect 22. The method of aspect 20, the method comprising contacting a bi-, tri- or higher-valent boride with a quaternary ammonium salt and / or a base to produce a nanofibrous product.

[0251] Aspect 23. The method of aspect 22, wherein the diboride comprises one or more titanium borides.

[0252] Aspect 24. The method of aspect 22, wherein the quaternary ammonium salt and / or the base comprises ammonium hydroxide, ammonium halide, or any combination thereof.

[0253] Aspect 25. The method of aspect 24, wherein the ammonium hydroxide comprises tetramethylammonium hydroxide (TMAOH), tetraethylammonium hydroxide (TEAOH), tetrapropylammonium hydroxide (TPAOH), tetrabutylammonium hydroxide (TBAOH), ammonium hydroxide (NH 4 OH), their amine derivatives, or any combination thereof.

[0254] Aspect 26. The method of aspect 24, wherein the quaternary ammonium salt comprises quaternary ammonium chloride, quaternary ammonium bromide, quaternary ammonium iodide, quaternary ammonium fluoride, or any combination thereof.

[0255] Aspect 27. The method of aspect 20, the method further comprising filtering the product.

[0256] Aspect 28. The method of aspect 20, the method further comprising washing the product with a metal salt and / or other water-soluble metal compound.

[0257] Aspect 29. The method of aspect 20, the method further comprising washing the product with a metal salt and / or a water-soluble metal compound, the metal salt optionally comprising a metal sulfate, nitrate, chromate, acetate, carbonate, permanganate or metal hydroxide, or any combination thereof.

[0258] Aspect 30. The method of aspect 29, wherein the metal in the metal salt comprises Li, Na, K, Cs, Mg, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Cd, Ta or W, or any combination thereof.

[0259] Aspect 31. The method of aspect 29, wherein the metal salt comprises LiCl, KCl, NaCl, CsCl, LiF, KF, NaF, LiOH, KOH, NaOH, or any combination thereof.

[0260] Aspect 32. The method of aspect 29, wherein the metal salt comprises CrCl 3 , MnCl 2 , FeCl 2 , FeCl 3 , CoCl 2 , NiCl 2 , MoCl 5 , FeSO 4 , (NH 4 ) 2 Fe(SO 4 ) 2 , CuCl 2 , CuCl, ZnCl 2 , or any combination thereof.

[0261] Aspect 33. The method of aspect 20, wherein the product is the composition according to aspect 1.

[0262] Aspect 34. A method, the method comprising: contacting particulate TiO 2 with a quaternary ammonium salt and / or a base, the contacting being carried out under conditions sufficient to produce a nanoparticle product, the nanoparticle product optionally having at least some nanoparticles with a diameter of about 2 nm to about 1000 nm, optionally about 10 nm to about 100 nm.

[0263] Aspect 35. The method of aspect 34, wherein the quaternary ammonium salt and / or the base comprises ammonium hydroxide, ammonium halide, or any combination thereof.

[0264] Aspect 36. The method of aspect 34, wherein the quaternary ammonium base comprises tetramethylammonium hydroxide (TMAOH), tetraethylammonium hydroxide (TEAOH), tetrapropylammonium hydroxide (TPAOH), tetrabutylammonium hydroxide (TBAOH), ammonium hydroxide (NH4 OH), their amine derivatives, or any combination thereof.

[0265] Aspect 37. The method of aspect 34, wherein the quaternary ammonium salt comprises quaternary ammonium chloride, quaternary ammonium bromide, quaternary ammonium iodide, quaternary ammonium fluoride, or any combination thereof and a base.

[0266] Aspect 38. The method of aspect 34, the method further comprising filtering the product.

[0267] Aspect 39. A composition comprising a population of nanoparticles prepared according to aspect 34.

[0268] Aspect 40. A method comprising replacing TiO with a population of nanoparticles prepared according to aspect 34 2 .

[0269] Aspect 41. A method comprising: contacting a monovalent, divalent, trivalent or higher valent carbide, nitride, boride, phosphide, aluminate or silicide or titanium metal with a quaternary ammonium salt and / or a base, the monovalent, divalent, trivalent or higher valent carbide, nitride, boride, phosphide, aluminate or silicide or titanium metal being optionally water-insoluble, the water-insoluble divalent, trivalent or higher valent carbide, nitride, boride, phosphide, aluminate or silicide optionally containing a transition metal, the transition metal optionally containing titanium, the contacting optionally being carried out while oscillating, and the contacting being carried out under conditions sufficient to produce mesoporous particles.

[0270] Aspect 42. A method comprising: contacting a monovalent, divalent, trivalent or higher valent carbide, nitride, boride, phosphide, aluminate or silicide or titanium metal with a quaternary ammonium salt and / or a base, the monovalent, divalent, trivalent or higher valent carbide, nitride, boride, phosphide, aluminate or silicide or titanium metal being optionally water-insoluble, the water-insoluble divalent, trivalent or higher valent carbide, nitride, boride, phosphide, aluminate or silicide optionally containing a transition metal, the transition metal optionally containing titanium, the contacting optionally being carried out while oscillating, the contacting being followed by washing with at least one salt, and the contacting being carried out under conditions sufficient to produce mesoporous particles.

[0271] Aspect 43. A method, the method comprising: contacting a mono-, di-, tri- or higher-order carbide, nitride, boride, phosphide, aluminate or silicide or titanium metal with a quaternary ammonium salt and / or a base, the mono-, di-, tri- or higher-order carbide, nitride, boride, phosphide, aluminate or silicide or titanium metal being optionally water-insoluble, the water-insoluble di-, tri- or higher-order carbide, nitride, boride, phosphide, aluminate or silicide optionally containing a transition metal, the transition metal optionally containing titanium, the contacting being carried out while oscillating and at a temperature of about 50 °C to about 95 °C, and subsequently washing with LiCl to produce mesoporous particles.

[0272] Aspect 44. A composition comprising the mesoporous particles prepared according to any one of Aspects 41-43.

[0273] Aspect 45. The composition according to Aspect 44, further comprising a therapeutic agent.

[0274] Aspect 46. An electrode comprising the composition according to Aspect 44.

[0275] Aspect 47. A device comprising the composition according to Aspect 44.

[0276] Aspect 48. The device of Aspect 47, wherein the device is an energy storage device.

[0277] Aspect 49. A method comprising operating the device of Aspect 47.

[0278] Aspect 50. A mesoporous particle comprising: a plurality of goethite nanofibers, the plurality of goethite nanofibers optionally containing Ti, the diameter of the mesoporous particle being in the range of about 1 μm to about 30 μm.

[0279] Aspect 51. The mesoporous particle of Aspect 50, wherein the diameter of the mesoporous particle is about 2 μm to about 25 μm.

[0280] Aspect 52. The mesoporous particle of Aspect 50, wherein the nanofibers contain a plurality of Ti atoms arranged in a zigzag pattern.

[0281] Aspect 53. A composition comprising a plurality of the mesoporous particles according to Aspect 50.

[0282] Aspect 54. A colloid comprising a plurality of the mesoporous particles according to Aspect 50.

[0283] Aspect 55. The colloid of Aspect 54, wherein a plurality of mesoporous particles are suspended in water.

[0284] Aspect 56. The colloid of Aspect 54, wherein a plurality of mesoporous particles are suspended in an aqueous medium.

Claims

1. A composition comprising: a plurality of metal oxide sub-nanowires and / or nanowires, said sub-nanowires and / or nanowires optionally comprising goethite regions, said plurality of metal oxide sub-nanowires and / or nanowires optionally comprising a certain amount of carbon, said plurality of metal oxide sub-nanowires and / or nanowires optionally being contained in bundles, sheets, or both sheets and bundles.

2. The composition according to claim 1, wherein at least some of the nanofibers and / or sub-nanofibers have a width in the range of about to about .

3. The composition according to claim 1, wherein at least some of said nanowires and / or sub-nanowires comprise Ti atoms.

4. The composition according to claim 1, wherein said nanowires and / or sub-nanowires define a non-circular cross-section.

5. The composition according to claim 4, wherein said nanowires and / or sub-nanowires define a cross-sectional aspect ratio greater than 1 to about 10.

6. The composition according to claim 5, wherein said nanowires and / or sub-nanowires define a cross-sectional aspect ratio of about 2 to about 5.

7. The composition according to claim 1, wherein the nanofibers and / or sub-nanofibers have an average cross-sectional area in the range of about to about .

8. The composition according to claim 1, wherein at least some of said nanowires and / or sub-nanowires have a length in the range of 1 nm to about 25 μm.

9. The composition according to claim 8, wherein at least some of said nanowires and / or sub-nanowires have a length in the range of 1 nm to about 1 μm.

10. The composition according to claim 1, wherein said nanowires and / or sub-nanowires are contained in a plurality of sheets.

11. The composition according to claim 1, wherein at least some of the plurality of nanowires and / or sub-nanowires lie in a common plane.

12. The composition according to any one of claims 1-11, further comprising a pharmaceutically acceptable carrier.

13. The composition according to claim 1, further comprising an adhesive.

14. The composition according to claim 13, wherein said adhesive comprises a polymer.

15. A device comprising the composition according to claim 1.

16. The device according to claim 15, wherein the device is characterized as an energy storage device.

17. The device according to claim 15, wherein the device comprises an electrode.

18. The device according to claim 17, wherein the electrode comprises the composition according to claim 1.

19. The device according to claim 15, wherein the device comprises a dispenser in which the composition according to claim 1 is provided.

20. A method comprising: contacting a mono-, bi-, tri- or higher-valent carbide, nitride, boride, phosphide, aluminate or silicide or titanium metal with a quaternary ammonium salt and / or a base, said mono-, bi-, tri- or higher-valent carbide, nitride, boride, phosphide, aluminate or silicide or titanium metal optionally being water-insoluble, said water-insoluble bi-, tri- or higher-valent carbide, nitride, boride, phosphide, aluminate or silicide optionally comprising a transition metal, said transition metal optionally comprising titanium, said contacting being carried out under conditions sufficient to produce a nanofilamentous product.

21. The method according to claim 20, wherein the conditions include a temperature of 0 °C to 100 °C for about 5 hours to about 1 week.

22. The method according to claim 20, the method comprising contacting a binary, ternary or higher boride with a quaternary ammonium salt and / or a base to produce a nanofibrous product.

23. The method according to claim 22, wherein the binary boride comprises one or more titanium borides.

24. The method according to claim 22, wherein the quaternary ammonium salt and / or the base comprises ammonium hydroxide, ammonium halide, or any combination thereof.

25. The method according to claim 24, wherein the ammonium hydroxide comprises tetramethylammonium hydroxide (TMAOH), tetraethylammonium hydroxide (TEAOH), tetrapropylammonium hydroxide (TPAOH), tetrabutylammonium hydroxide (TBAOH), ammonium hydroxide (NH 4 OH), their amine derivatives, or any combination thereof.

26. The method according to claim 24, wherein the quaternary ammonium salt comprises quaternary ammonium chloride, quaternary ammonium bromide, quaternary ammonium iodide, quaternary ammonium fluoride, or any combination thereof.

27. The method according to claim 20, the method further comprising filtering the product.

28. The method according to claim 20, the method further comprising washing the product with a metal salt and / or other water-soluble metal compound.

29. The method according to claim 20, the method further comprising washing the product with a metal salt and / or a water-soluble metal compound, the metal salt optionally comprising a sulfate, nitrate, chromate, acetate, carbonate, permanganate of a metal or a metal hydroxide, or any combination thereof.

30. The method according to claim 29, wherein the metal in the metal salt comprises Li, Na, K, Cs, Mg, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Cd, Ta or W, or any combination thereof.

31. The method according to claim 29, wherein the metal salt comprises LiCl, KCl, NaCl, CsCl, LiF, KF, NaF, LiOH, KOH, NaOH, or any combination thereof.

32. The method according to claim 29, wherein the metal salt comprises CrCl 3 , MnCl 2 , FeCl 2 , FeCl 3 , CoCl 2 , NiCl 2 , MoCl 5 , FeSO 4 , (NH 4 ) 2 Fe(SO 4 ) 2 , CuCl 2 , CuCl, ZnCl 2 , or any combination thereof.

33. The method according to claim 20, wherein the product is the composition according to claim 1.

34. A method, the method comprising: Contact granular TiO 2 with a quaternary ammonium salt and / or a base, the contacting is carried out under conditions sufficient to produce a nanoparticle product, the nanoparticle product optionally having at least some nanoparticles with a diameter of about 2 nm to about 1000 nm, optionally about 10 nm to about 100 nm.

35. The method according to claim 34, wherein the quaternary ammonium salt and / or the base comprises ammonium hydroxide, ammonium halide, or any combination thereof.

36. The method according to claim 34, wherein the quaternary ammonium base comprises tetramethylammonium hydroxide (TMAOH), tetraethylammonium hydroxide (TEAOH), tetrapropylammonium hydroxide (TPAOH), tetrabutylammonium hydroxide (TBAOH), ammonium hydroxide (NH 4 OH), their amine derivatives, or any combination thereof.

37. The method according to claim 34, wherein the quaternary ammonium salt comprises quaternary ammonium chloride, quaternary ammonium bromide, quaternary ammonium iodide, quaternary ammonium fluoride, or any combination thereof and a base.

38. The method according to claim 34, which further comprises filtering the product.

39. A composition comprising a population of nanoparticles prepared according to claim 34.

40. A method, the method comprising replacing TiO with a population of nanoparticles prepared according to claim 34 2 .

41. A method, the method comprising: contacting a mono-, bi-, tri- or higher carbide, nitride, boride, phosphide, aluminate or silicide or titanium metal with a quaternary ammonium salt and / or a base, the mono-, bi-, tri- or higher carbide, nitride, boride, phosphide, aluminate or silicide or titanium metal optionally being water-insoluble, The non-water-soluble binary, ternary or higher-order carbides, nitrides, borides, phosphides, aluminides or silicides optionally contain transition metals, and the transition metals optionally contain titanium. The contacting is optionally carried out while oscillating, and the contacting is carried out under conditions sufficient to produce mesoporous particles.

42. A method, the method comprises: contacting a mono-, bi-, tri- or higher-order carbide, nitride, boride, phosphide, aluminide or silicide or titanium metal with a quaternary ammonium salt and / or a base, the mono-, bi-, tri- or higher-order carbide, nitride, boride, phosphide, aluminide or silicide or titanium metal is optionally non-water-soluble, the non-water-soluble binary, ternary or higher-order carbides, nitrides, borides, phosphides, aluminide or silicide optionally contain transition metals, and the transition metals optionally contain titanium, the contacting is optionally carried out while oscillating, the contacting is followed by washing with at least one salt, and the contacting is carried out under conditions sufficient to produce mesoporous particles.

43. A method, the method comprises: contacting a mono-, bi-, tri- or higher-order carbide, nitride, boride, phosphide, aluminide or silicide or titanium metal with a quaternary ammonium salt and / or a base, the mono-, bi-, tri- or higher-order carbide, nitride, boride, phosphide, aluminide or silicide or titanium metal is optionally non-water-soluble, the non-water-soluble binary, ternary or higher-order carbides, nitrides, borides, phosphides, aluminide or silicide optionally contain transition metals, and the transition metals optionally contain titanium, the contacting is carried out while oscillating and at a temperature of about 50 °C to about 95 °C, and then washing with LiCl to produce mesoporous particles.

44. A composition comprising the mesoporous particles prepared according to any one of claims 41-43.

45. The composition according to claim 44, further comprising a therapeutic agent.

46. An electrode comprising the composition according to claim 44.

47. A device comprising the composition according to claim 44.

48. The device according to claim 47, wherein the device is an energy storage device.

49. A method comprising operating the device according to claim 47.

50. A mesoporous particle comprising: a plurality of goethite nanofibers, the plurality of goethite nanofibers optionally contain Ti, the mesoporous particle has a diameter in the range of about 1 μm to about 30 μm.

51. The mesoporous particle according to claim 50, wherein the mesoporous particle has a diameter of about 2 μm to about 25 μm.

52. The mesoporous particle according to claim 50, wherein the nanofibers contain a plurality of Ti atoms arranged in a zigzag pattern.

53. A composition comprising a plurality of the mesoporous particles according to claim 50.

54. A colloid comprising a plurality of the mesoporous particles according to claim 50.

55. The colloid according to claim 54, wherein a plurality of mesoporous particles are suspended in water.

56. The colloid according to claim 54, wherein a plurality of mesoporous particles are suspended in an aqueous medium.

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