Hybrid structures for hydrogen storage

Abstract

A hydrogen storage system comprising (i) a nanoporous solid; (ii) an aqueous fluid-promoter mixture and (iii) one or more pressure-inducing liquids. A method of storing hydrogen comprising contacting a nanoporous solid with an aqueous fluid-promoter mixture under conditions suitable for the formation of a hydrated solid; and contacting the hydrated solid with at least one pressure-inducing liquid under conditions suitable for the formation of a hydrogen storage material.

Description

HYBRID STRUCTURES FOR HYDROGEN STORAGECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of U.S. Provisional Patent Application Serial No. 63 / 614,000 filed December 22, 2023 and entitled “HIGH-CAPACITY HYDROGEN STORAGE THROUGH HYBRID SOLID-LIQUID STRUCTURES,” which is hereby incorporated herein by reference in its entirety for all purposes.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] This invention was made with government support under N000114-23-1-2034 awarded by the Office of Naval Research. The government has certain rights in the invention.TECHNICAL FIELD

[0003] The present disclosure relates to renewable energy systems. More specifically, the present disclosure relates methods and compositions for hydrogen storage.BACKGROUND

[0004] In the evolving context of sustainable energy and the global challenge of climate change, hydrogen has emerged as a key component in both stationary and portable energy systems, currently contributing to 18% of the total energy demand. Hydrogen has the potential to address two major challenges in the global drive to achieve net zero emissions by 2050. First, it can help tackle the perennial issue of the intermittency of renewable energy sources such as wind and solar. By converting excess power generated on windy or sunny days into hydrogen, the gas can store renewable energy that can then be dispatched at times of peak demand as a clean fuel source for power generation. Second, hydrogen can replace fossil fuels to decarbonize sectors where electrification alone won’t suffice, such as domestic heating, industry, shipping and aviation.SUMMARY

[0005] Disclosed herein is a hydrogen storage system comprising (i) a nanoporous solid; (ii) an aqueous fluid-promoter mixture and (iii) one or more pressure-inducing liquids.

[0006] Also disclosed herein is a method of storing hydrogen comprising contacting a nanoporous solid with an aqueous fluid-promoter mixture under conditions suitable forthe formation of a hydrated solid; and contacting the hydrated solid with at least one pressure-inducing liquid under conditions suitable for the formation of a hydrogen storage material.

[0007] Embodiments described herein comprise a combination of features and characteristics intended to address various shortcomings associated with certain prior devices, systems, and methods. The foregoing has outlined rather broadly the features and technical characteristics of the disclosed embodiments in order that the detailed description that follows may be better understood. The various characteristics and features described above, as well as others, will be readily apparent to those skilled in the art upon reading the following detailed description, and by referring to the accompanying drawings. It should be appreciated that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes as the disclosed embodiments. It should also be realized that such equivalent constructions do not depart from the spirit and scope of the principles disclosed herein.BRIEF DESCRIPTION OF THE FIGURES

[0008] For a detailed description of various exemplary embodiments, reference will now be made to the accompanying drawings in which:

[0009] Figure 1A is a schematic illustration of an aspect of the disclosed solid liquid storage material (SLSM) platform designed for high-capacity hydrogen storage, featuring an SLSM with a pore diameter of 2.4 nm positioned at the bottom of the chamber.

[0010] Figure 1 B is a schematic depiction of the SLSM platform where 'IT denotes the first layer of octane, representing the outermost layer. 12' refers to the silicon oil layer, 13' to the second octane layer, and 14' is the innermost layer consisting of the water / THF layer.

[0011] Figure 1 C a photograph of an SLSM illustrating the layered structure.

[0012] Figure 1 D is a plot of the interfacial tension between octane and the water / THF solution at varying concentrations of sodium dodecyl (SDS).

[0013] Figure 1 E is a plot of the pressure of a droplet (Pd) computed based on the Laplace equation for the different layers of the SLSM.

[0014] Figure 2A is a plot of the volumetric flow rate of hydrogen as a function of time during hydrate formation in an exemplary SLSM with water and tetrahydrofuran (THF).

[0015] Figure 2B is a plot of the hydrogen pressure as a function of time during hydrate formation in an exemplary SLSM with water and THF .

[0016] Figure 2C is a plot of the system temperature as a function of time during hydrate formation in an exemplary SLSM with water and THF.

[0017] Figure 2D is a plot of the volumetric flow rate of hydrogen as a function of time during hydrate formation in an exemplary SLSM with water and tetrahydrothiophene (THT).

[0018] Figure 2E is a plot of the hydrogen pressure as a function of time during hydrate formation in an exemplary SLSM with water and THT .

[0019] Figure 2F is a plot of the system temperature as a function of time during hydrate formation in an exemplary SLSM with water and THT.

[0020] Figure 3A depicts the Fourier transform infrared spectroscopy (FTIR) peaks for the indicated configuration of confined water.

[0021] Figure 3B is the FTIR spectra of a sample of bulk water with a THF promoter.

[0022] Figure 3C is the FTI spectra of a sample of ice water with a THF promoter.

[0023] Figure 3D is an FTIR spectra of an SLSM of the present disclosure.

[0024] Figure 3E is an X-ray diffraction spectra (XRD) of an SLSM of the present disclosure in the absence of hydrogen at 25 °C.

[0025] Figure 3F is an XRD of an SLSM of the present disclosure in the absence of hydrogen at -78 °C.

[0026] Figure 3G is an XRD of an SLSM of the present disclosure in the presence of hydrogen at -78 °C.

[0027] Figure 4A is a bar graph of storage capacity as a function of pressure for an SLSM or a bulk water / THF solution.

[0028] Figure 4B is a plot of storage capacity as a function of pressure for the indicated materials.

[0029] Figure 5A is a plot of charging time at the indicated pressure for the indicated materials.

[0030] Figure 5B is a plot of discharging time at the indicated pressure for the indicated materials.

[0031] Figure 5C is a bar graph of the charging time for the indicated samples.

[0032] Figure 5D is plot of the storgage capacity and charging time of an SLSM of the present disclosure as a function of cycle number.DETAILED DESCRIPTION

[0033] The following discussion is directed to various exemplary embodiments. However, one skilled in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

[0034] Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.

[0035] Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints, and open-ended ranges should be interpreted to include only commercially practical values. In addition, with respect to all ranges disclosed herein, such ranges are intended to include any combination of the mentioned upper and lower limits even if the particular combination is not specifically listed. All lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11 , 0.12, 0.13, etc.).

[0036] In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to... .” As used herein, the phrases “consist(s) of’ and “consisting of” are used to refer to exclusive components of a composition, meaning only those expressly recited components are included in the composition; whereas the phrases “consist(s) essentially of’ and “consisting essentially of” are used to refer to the primary components of a composition, meaning that only small or trace amounts of components other than the expressly recited components (e.g., impurities,byproducts, etc. ) may be included in the composition. For example, a composition consisting of X and Y refers to a composition that only includes X and Y, and thus, does not include any other components ; and a composition consisting essentially of X and Y refers to a composition that primarily comprises X and Y, but may include small or trace amounts of components other than X and Y. In embodiments described herein , any such small or trace amounts of components other than those expressly recited following the phrase “consist (s) essentially of’ or “consisting essentially of’ preferably represent less than 5.0 wt% of the composition, more preferably less than 4.0 wt% of the composition, even more preferably less than 3.0 wt% of the composition, and still more preferably less than 1.0 wt% of the composition. Use of broader terms such as comprises, includes, having, etc. should be understood to provide support for narrower terms such as consisting of, consisting essentially of, comprised substantially of, etc. Use of the term "optionally" with respect to any element of a claim is intended to mean that the subject element is required, or alternatively, is not required. Both alternatives are intended to be within the scope of the claim.

[0037] As used herein, the terms “approximately,” “about,” “substantially,” and the like mean within 10% (i.e., plus or minus 10%) of the recited value. Thus, for example, a recited angle of “about 80 degrees” refers to an angle ranging from 72 degrees to 88 degrees.

[0038] The necessity for high-capacity, safe, and cost-effective hydrogen storage is paramount in advancing the hydrogen economy, but still, it remains a challenge. Factors contributing to the challenges in storing hydrogen include (i) a low volumetric energy density compared to other gases; (ii) a boiling point close to absolute zero meaning storage requires cryogenic temperatures; and (ii) the ability to corrode metal containers under certain conditions.

[0039] Various advanced material systems, such as metal hydrides, metal-organic frameworks, and 2D materials, have been investigated as systems hydrogen storage with the potential for high storage capacities. However, limitations due to high operating pressures, slow charging / discharging rates, and energy-intensive discharging processes have impeded their further development. Thus, an ongoing need exists for methods and compositions for use in hydrogen storage that addresses some of the aforementioned challenges.

[0040] Disclosed herein are compositions and methods for the storage of hydrogen In one or more aspects, hydrogen is stored in a solid liquid storage material (SLSM) comprising (i) a nanoporous solid; (ii) an aqueous promoter; and (iii) one or more pressure-inducing liquids. In some aspects, a method of preparing an SLSM comprises impregnation of the nanoporous solid with an aqueous fluid-promoter mixture to form an impregnated nanoporous solid; charging of the impregnated nanoporous solid with hydrogen under conditions suitable for formation of hydrogen-containing nanoporous solid and creating a pressure-inducing film on at least a portion of the hydrogencontaining nanoporous solids to form the SLSM.

[0041] In one or more aspects, the nanoporous solid is characterized by the presence of nanopores with a pore-size regime ranging from about 1 nanometers (nm) to about 1000 nm or from about 1.5 nm to 100 nm or from about 1.75 nm to about 10 nm. In one or more aspects, the solid has 50% of the total amount of pores present as nanopores of the type disclosed herein, or equal to or greater than about 75%, or equal to or greater than about 85%, or equal to or greater than about 90%.

[0042] Nonlimiting examples of nanoporous solids suitable for use in the present disclosure include metal-organic frameworks, zeolites, ceramics, activated carbon, silicates, polymeric materials, aerogels, pillared materials, inorganic porous hybrid materials and combinations thereof. In an aspect, the nanoporous solid comprises silica.

[0043] In one or more aspects, a method of the present disclosure comprises contacting a nanoporous solid with mixture comprising an aqueous fluid, such as deionized water and a promoter. In an aspect, the promoter is any compound or mixture of compounds that facilitates nucleation of a hydrogen hydrate within the nanoporous solid. Nonlimiting examples of promoters include tetrahydrofuran (THF), 1 ,3-dioxolane, cyclopentane, tetrahydrothiophene, argon, nitrogen, or combinations thereof. The promoter may be present in an amount that provides a final percentage of promoter that ranges from about 1 weight percent (wt.%) to about 20 wt.% based on the total weight of the mixture, or from about 2 wt.% to about 18 wt.%, or from about 3 wt.% to about 15 wt.%, or from about 4 wt.% to about 12 wt.%, or from about 5 wt.% to about 10 wt.%.

[0044] Contacting of the aqueous fluid-promoter mixture with the nanoporous solid may be carried out using any suitable methodology and at temperatures ranging from about -20 °C to about 0 °C For example, the nanoporous solid may be immersed in a solution of the aqueous fluid-promoter mixture. In other aspects, the aqueous-fluid promotermixture is injected into the nanoporous solid. In either aspect, the nanoporous solid contacted with the aqueous fluid-promoter mixture may be treated to reduce the amount of aqueous fluid on the surface of the solid and increase the amount of aqueous fluid present in the pores of the material. For example, the nanoporous solid following contact with the aqueous fluid-promoter mixture may be centrifuged. The resulting material is termed a hydrated nanoporous solid.

[0045] In one or more aspects, the hydrated nanoporous solid is contacted with one or more pressure-inducing liquids. Any liquid able to create a liquid-liquid interface with the aqueous fluid-promoter mixture having an interfacial tension of equal to or greater than about 20 milliNewtons per meter (mN / m) may be used. In an aspect, a first pressureinducing liquid suitable for use in the present disclosure creates a liquid-liquid interfacial tension of equal to or greater than about 25 mN / m, or equal to or greater than about 30 mN / m, or equal to or greater than about 35 mN / m, or equal to or greater than about 40 mN / m, or equal to or greater than about 45 mN / m, or equal to or greater than about 50 mN / m, or from about 20 mN / m to about 70 mN / m, or from about 25 mN / m to about 65 mN / m, or from about 30 mN / m to about 60 mN / m, or from about 35 mN / m to about 55 mN / m.

[0046] In one or more aspects, the pressure-inducing liquid comprises a mixture of a hydrocarbon and a surfactant such as sodium dodecyl sulfate (SDS).

[0047] In one or more aspects, the hydrocarbon is an aliphatic hydrocarbon. For example, the aliphatic hydrocarbon may comprise a C3 to C20 aliphatic hydrocarbons or a C4 to C15 aliphatic hydrocarbons; or a C5 to C10 aliphatic hydrocarbons. Non-limiting examples of suitable acyclic aliphatic hydrocarbon include propane, iso-butane, n- butane, butane (n-butane or a mixture of linear and branched C4 acyclic aliphatic hydrocarbons), pentane (n-pentane or a mixture of linear and branched Cs acyclic aliphatic hydrocarbons), hexane (n-hexane or mixture of linear and branched Cs acyclic aliphatic hydrocarbons), heptane (n-heptane or mixture of linear and branched C7 acyclic aliphatic hydrocarbons), octane (n-octane or a mixture of linear and branched Cs acyclic aliphatic hydrocarbons), and combinations thereof.

[0048] The mixture of hydrocarbon and surfactant is a pressure-inducing-liquid that may form a layer (h) covering at least a portion of the hydrated nanoporous solid surface. For example, equal to or greater than about 50% of the hydrated nanoporous solid surface, or equal to or greater than about 75% or equal to or greater than about 85%. In some aspects, h forms a layer that covers about 100% of the surface of the hydratednanoporous solid. The hydrated nanoporous solid with a h is herein termed a pressurized solid.

[0049] In an aspect, the pressurized solid is contacted with a modifying liquid that functions to adjust the thickness of h to achieve one or more user or process goals. For example, the modifying liquid may comprise any water-immiscible liquid, for example silicone. Silicone may form a second layer I2 adjacent to the first layer comprising the pressure-inducing liquid, h. Hereinafter, the pressurized solid having the octane layer adjusted by the modifying liquid is termed the adjusted pressurized solid. In some aspects, the adjusted pressurized solid is contacted with a second pressure-inducing liquid to form a third layer, I3. The second pressure-inducing liquid may be the same or different from the first pressure-inducing liquid. The adjusted pressurized solid having one or more additional layers of a pressure-inducing liquid is termed the SLSM.

[0050] In one or more aspects, each liquid layer in the SLSM has a thickness ranging from about 1 nm to about 100 nm or from about 2 nm to about 50 or from about 10 nm to about 25 nm. An exemplary aspect of a hydrogen storage device comprising an SLSM is depicted schematically in Figure 1A. Figure 1 B, depicts an exemplary SLSM while Figure 1 C depicts a layered hydrogen storage system of the present disclosure.

[0051] Without wishing to be limited by theory, an aqueous fluid-promoter mixture of the present disclosure coupled with the concavity of the nanopores facilitates the ordering of water within the pores of the nanoporous solid and formation of hydrogen hydrate. Further, the pressure-inducing liquid functions to create a liquid-liquid interfacial tension that is directly related to the hydrogen storage capacity of the nanoporous solid.

[0052] In an aspect, a method of the present disclosure further comprises charging the SLSM with hydrogen. Any method of the charging the SLSM with hydrogen may be used such as contacting the SLSM with a hydrogen stream within a closed vessel.

[0053] The charged-SLM may have an amount of hydrogen hydrate captured ranging from about 0.1 wt.% to about 5 wt.% based on the total weight of the SLSM or from about 0.5 wt.% to about 2.5 wt.% or from about 1 wt.% to about 2 wt.%.

[0054] In one or more aspects, the charged SLSM is discharged to release hydrogen. Discharging of the charged SLSM may be carried out by subjecting the charged SLSM to alterations in temperatures, pressures or both. In one or more aspects, the charged SLSM may be discharged by removal of the aqueous fluid-promoter mixture.

[0055] Hydrogen storage systems are essential for the successful shift to sustainable energy, offering approaches to mitigate climate challenges. The principal advantages ofthese systems include high storage capacities at moderate pressures and temperatures, fast charging and discharging, as well as cost-effectiveness and safety. The presently disclosed SLSM surprisingly allows for the restructuring of water and a high droplet pressure resulting in a storage capacity of hydrogen hydrate that is increased by over two orders of magnitude when compared to other storage materials. It is also noteworthy that the temperature range for hydrogen storage materials was limited to -40 to 85 °C, in line with a United States Department of Energy target for 2025. Within these specified operating conditions, an SLSM of the present disclosure exhibits a higher storage capacity when compared to other state-of-the-art materials and suggests a groundbreaking platform for hydrogen storage.

[0056] Beyond high storage capacity, the presently disclosed SLSM displays additional benefits regarding charging / discharging rates when compared to existing materials. The SLSM has both the lowest charging pressure and remarkably also has one of the shortest charging times in comparison to other materials. For some materials, temperatures nearing 700 K are necessary for H2 to release. An SLSM of the present disclosure stands out as having one of the shortest discharging times at room temperatures. These performances underscore the potential of the SLSM as a hydrogen storage material.

[0057] The presently disclosed SLSM represents a novel material that stores hydrogen in the molecular structure of water, devoid of negative environmental impacts. An exemplary SLSSM comprises water, THF, octane, silicon oil and modified silica. Both water and THF are commodities, and modified silica can be produced through a well- established synthesis process, indicating the scalability potential of SLSM for application in both expansive stationary and compact mobile environments. Further, an SLSM having localized interfacial and confined hydrogen storage presented herein will facilitate the safe implementation of hydrogen across a diverse range of energy systems, encompassing power generation and land and sea transport.ADDITIONAL DISCLOSURE

[0058] A first aspect which is a hydrogen storage system comprising (i) a nanoporous solid; (ii) an aqueous fluid-promoter mixture and (iii) one or more pressure-inducing liquids.

[0059] A second aspect which is the system of the first aspect wherein the nanoporous solid has a pore size regime of from about 1 nm to about 1000 nm.

[0060] A third aspect which is the system of any of the first through second aspects wherein the nanoporous solid comprises metal-organic frameworks, zeolites, ceramics, activated carbon, silicates, polymeric materials, aerogels, pillared materials, inorganic porous hybrid materials or combinations thereof.

[0061] A fourth aspect which is the system of any of the first through third aspects wherein the aqueous fluid comprises deionized water.

[0062] A fifth aspect which is the system of any of the first through fourth aspects wherein the promoter comprises tetrahydrofuran (THF), 1 ,3-dioxolane, cyclopentane, tetrahydrothiophene, argon, nitrogen or conbinations thereof.

[0063] A sixth aspect which is the system of any of the first through fifth aspects wherein the promoter is present in the aqueous fluid-promoter mixture in an amount of from about 1 wt.% to about 20 wt.% based on the total weight of the aqueous fluid-promoter mixture.

[0064] A seventh aspect which is the system of any of the first through sixth aspects wherein the pressure-inducing liquid creates a liquid-liquid interface having an interfacial tension of equal to or greater than about 20 milliNewtons per meter.

[0065] An eighth aspect which is the system of any of the first through seventh aspects wherein the pressure-inducing liquid comprises an aliphatic hydrocarbon and a surfactant.

[0066] A ninth aspect which is the system of the eighth aspect wherein the aliphatic hydrocarbon comprises C3 to C20 aliphatic hydrocarbon.

[0067] A tenth aspect which is the system of the eighth aspect wherein the aliphatic hydrocarbon comprises propane, iso-butane, n-butane, butane (n-butane ora mixture of linear and branched C4 acyclic aliphatic hydrocarbons), a mixture of linear and branched C5 acyclic aliphatic hydrocarbons), hexane (n-hexane or mixture of linear and branched Cs acyclic aliphatic hydrocarbons), heptane (n-heptane or mixture of linear and branched C7 acyclic aliphatic hydrocarbons), octane (n-octane, a mixture of linear and branched Cs acyclic aliphatic hydrocarbons), or combinations thereof.

[0068] An eleventh aspect which is the system of any of the first through tenth apsects having a hydrogen storage capacity of from about 0.1 wt.% to about 5 wt.% based on the total weight of the system.

[0069] A twelfth aspect which is a method of storing hydrogen comprising contacting a nanoporous solid with an aqueous fluid-promoter mixture under conditions suitable for the formation of a hydrated solid; and contacting the hydrated solid with at least onepressure-inducing liquid under conditions suitable for the formation of a hydrogen storage material.

[0070] A thirteeenth aspect which is the method of the twelfth aspect wherein the nanoporous solid comprises metal-organic frameworks, zeolites, ceramics, activated carbon, silicates, polymeric materials, aerogels, pillared materials, inorganic porous hybrid materials or combinations thereof.

[0071] A fourteenth aspect which is the method of any of the twelfth through thirteenth aspects wherein the nanoporous solid comprises silica.

[0072] A fifteenth aspect which is the method of any of the twelfth through fourteenth aspects wherein the aqueous fluid comprises deionized water.

[0073] A sixteenth aspect which is the method of any of the twelfth through fifteenth aspects wherein the promoter comprises tetrahydrofuran (THF), 1 ,3-dioxolane, cyclopentane, tetrahydrothiophene, argon, nitrogen, or combinations thereof.

[0074] A seventeenth aspect which is the method of any of the twelfth through sixteenth aspects wherein the pressure-inducing liquid comprises an aliphatic hydrocarbon and a surfactant.

[0075] An eighteenth aspect which is the method of any of the twelfth through seventeenth aspects wherein the hydrogen storage material has a hydrogen storage capacity of from about 0.1 wt.% to about 5 wt.% based on the total weight of the hydrogen storage material.

[0076] A ninteenth aspect which is the method of any of the twelfth through eighteenth aspects further comprising charging the hydrogen storage material at a pressure ranging of from about 4 bar to about 12 bar.

[0077] A twentieth aspect which is the method of any of the twelfth through nineteenth aspects further comprising charging the hydrogen storage material at a temperature ranging from about -40 °C to about 85 °C.EXAMPLES

[0078] The following examples are given as particular aspects of the present disclosure and demonstrate the practice and advantages thereof. It is understood that the examples are given by way of illustration and are not intended to limit the specification or the claims to follow in any manner.EXAMPLE 1

[0079] The interfacial tension between octane and a water / THF mixture was measured as a function of SDS concentration using the pendant drop method as described by Saad, S. M. I., Policova, Z. & Neumann, A. W. Design and accuracy of pendant drop methods for surface tension measurement. Colloids Surf A Physicochem Eng Asp 384, 442-452 (2011 ). The results are presented in Figure 1D.

[0080] The data demonstrate that the highest interfacial tension was achieved using THF containing 1.387 mM SDS. The interfacial tension between each layer was measured, and then by utilizing the Laplace pressure equation, the pressure each layer exerts on water was calculated and the results plotted in Figure 1 E. With reference to Figure 1 E, the final pressure within the water layer was approximately 1200 bar.EXAMPLE 2

[0081] An SLSM comprising silica, approximately 2 g, was utilized for hydrogen storage through hydrogen hydrates. A closed system comprising water, a 10 mol% THF promoter, SLSM, and H2 gas. To initiate the hydrogen storage experiment, the SLSM was placed at the bottom of a chamber, which was then with H2 gas. As depicted in Figure 2A, hydrate formation proceeded in two distinct phases: (i) hydrogen diffusion in water and (ii) hydrate nucleation and growth. There was an induction period between these phases due to the necessary time it takes to establish stable hydrate nuclei capable of forming hydrate crystals. During the diffusion of hydrogen gas in the hydrate, the chamber pressure tended to decrease. To counter the pressure drop, the chamber was connected to a hydrogen cylinder, which ensured pressure stability and simulated isobaric conditions at approximately 10 bar, Figure 2B. During the initial phase of the experiment, water / THF was saturated with hydrogen at 5°C, which was then followed by a stepwise reduction in temperature to initiate hydrate formation. As the temperature decreased, the hydrogen flow rate into the chamber was increased to maintain constant pressure. The flow rate was monitored using a flow meter with a maximum capacity of 10 ml / min. After the induction period, hydrate phase nucleation began at the pore wallwater interface, as indicated by a significant increase in the volumetric flow rate. A concurrent peak in the temperature curve, corresponding with the increased hydrogen flow rate through the chamber, signified the heat release due to exothermic hydrate formation reaction. The temperature graph in Figure 2C focused on the range where hydrate formation occurs, and the full scale of temperature graph. Once hydrate formation was initiated, the experiment proceeded until the flow rate reached zero,signifying completion of hydrate formation. The sample was then extracted at dry ice temperature for further characterization and analysis. Additionally, to account for the effect of temperature on the volumetric flow calculation a control experiment using an empty chamber was performed. The flow rate in the control experiment within the chamber aligned closely with the SLSM experiment until a marked increase in the SLSM experiment indicated hydrate formation.

[0082] A similar procedure was performed with a solution of water and 10% THT (tetrahydrothiophene) as the promotor. The results are displayed in Figures 2D-F. The capacity of THT surpassed thatofTHF; however, THT emitted a strong odor, preventing sample analysis by XRD and NMR.EXAMPLE 3

[0083] The specific surface chemistry of an SLSM was investigated. The types of bonding present in the water molecules of a bulk water / THF mixture when confined within SLSM pores are depicted in Figure 3A. In Figure 3A the different bonding configurations of confined water are designated as follows: DA is a donor acceptor; DDA is a double donor single acceptor; DDAA is a double donor- double acceptor and DAA is a single donor-double acceptor.

[0084] The bonding configurations of water in the bulk water / THF mixture, ice water / THF mixture and an SLSM were analyzed through Fourier Transform infrared (FTIR) spectroscopy, Figure 3B, 3C and 3D, respectively. The FTIR results in Figures 3B, 3C and 3D show that water confined in SLSM pores exhibits a higher number of double donor double acceptor (DDAA)bonds relative to donor acceptor (DA)DA bonds, implying the development of ice-like structures, thereby facilitating hydrate formations As observed in Figured 3B and 3D, the ratio of DDAA to DA in SLSM is 1 .3, whereas it is 0.94 in bulk water. FTIR was also performed on Water / THF ice, and as depicted in Figure 3B, the DDAA / DA ratio is 1.4, which is slightly greater than in the confined water / THF within SLSM. This suggests that the structure of water confined in SLSM resembles the structure of ice, which is favorable for hydrate formation. Figure 3A presents the raw data of SLSM, showcasing several datasets that demonstrated the repeatability of our research. From these datasets, one sample was selected and plotted both a single exponential fit and a distribution fit. The T2 value of SLSM, based on the single exponential fit, is 118 microseconds. In contrast, the T2 for bulk water is in the order of seconds, and for ice, it is around 1 microsecond, which falls below the minimumdetection threshold of our instrument. This suggests that we form a structure which is distinctly different from that of ice and bulk water.

[0085] To ascertain the presence of hydrogen hydrate, XRD and low frequency NMR analyses were performed on SLSM post-experiment. As shown in Figure 3E, XRD conducted on SLSM at room temperature displayed an amorphous structure, reflecting the non-crystalline nature of silica. In Figure 3F, XRD at dry ice temperature on SLSM in the absence of hydrogen, revealed that the water within SLSM has transitioned to ice, as indicated by the corresponding peaks in the XRD pattern. These peaks closely resemble of ice but exhibited slight deviations attributable to the confinement effect. The final XRD analysis of SLSM at dry ice temperature, presented in Figure 3G, exhibited distinctive peaks indicative of hydrate formation, which are dissimilar to those of ice, thereby substantiating the formation of a hydrate structure.EXAMPLE 4

[0086] The storage capacity of the SLSM was investigated. A storage capacity of 5.1 wt% is achievable for pure water but necessitates a substantially higher pressure of approximately 200 MPa. The total volume of hydrogen flow into the chamber can be calculated based on the volumetric flow rate curve presented in Figure 2A. Subsequently, the storage capacity of the SLSM was determined, by dividing the total mass of hydrogen consumption per total mass of the sample. As depicted in Figure 4A, the SLSM demonstrated storage capacities of 3.7 wt%, 3.45 wt%, and 3.33 wt% at pressures of 10, 8, and 6 bar, respectively. Also, the capacity of SLSM with THT was determined to be 4.2 wt%. The US Department of Energy (DOE) target for 2025 for onboard light-duty vehicles, material-handling equipment, and portable power applications are 5.5 % gravimetric storage capacity and 0.04 (kg Hydrogen / L System) volumetric storage capacity in the working pressure range of 5-12 bar with working temperature range of - 40°C to 85 °C. Regarding the volumetric storage capacity of the SLSM, by knowing the mass of hydrogen and the volume of sample, the volumetric capacity was calculated. The density of SLSM is 1.18 kg / m3; therefore, the volumetric storage capacity at 10 bar is 4.237 kg / m3. Figure 4B compared the hydrogen storage capacity of the SLSM and other state-of-the-art materials within the operational pressure range of 4-12 bar. It was also noteworthy that the temperature range for storage materials was limited to -40 to 85 °C, in line with DOE target for 2025. Within these specified operating conditions, the SLSM exhibited a higher storage capacity comparedto other state-of-the-art materials and suggests a groundbreaking platform for hydrogen storage.

[0087] Beyond high storage capacity, the SLSM presents additional benefits regarding charging / discharging rates as opposed to existing materials. The charging durations for various cutting-edge materials are illustrated in Figure 5A, with the charging pressure for each material indicated on their respective graphs. Despite SLSM having the lowest charging pressure, it remarkably also had one of the shortest charging times in comparison to other materials. The discharging durations for various hydrogen storage materials, along with their respective discharging temperatures, are presented in Figure 5B. The charging temperature for various samples are compared to that of an SLSM and the results are presented in Figure 5C. The storage capacity and charging time for an SLSM was plotted as a function of run cycles and the results are presented in Figure 5D. For the majority of these materials, the discharge process was performed at elevated temperatures or under vacuum conditions, which negatively affects the practical application of these materials. For some materials, temperatures nearing 700 K are necessary for H2 to release. An SLSM of the type disclosed herein stands out as having one of the shortest discharging times at room temperatures. The SLSMs of the present disclosure display short charging and discharging times. Further discharging of an SLSM can occur at ambient temperatures.These performances underscore the potential of an SLSM to present as a hydrogen storage material.

[0088] While preferred embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the systems, apparatus, and processes described herein are possible and are within the scope of the disclosure. For example, the relative dimensions of various parts, the materials from which the various parts are made, and other parameters can be varied. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. Unless expressly stated otherwise, the steps in a method claim may be performed in any order. The recitation of identifiers such as (a), (b), (c) or (1 ), (2), (3) before steps in a method claim are not intended to and do not specify a particular order to the steps, but rather are used to simplify subsequent reference to such steps.

[0089] Each and every claim is incorporated into the specification as an aspect of the present disclosure. Thus, the claims are a further description and are an addition to the aspects of the present invention. The discussion of a reference herein is not an admission that it is prior art to the presently disclosed subject matter, especially any reference that may have a publication date after the priority date of this application. The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference, to the extent that they provide exemplary, procedural or other details supplementary to those set forth herein. In the event of conflict, the present specification, including definitions, is intended to control.

Claims

CLAIMSWhat is claimed is:

1. A hydrogen storage system, comprising:(i) a nanoporous solid;(ii) an aqueous fluid-promoter mixture in contact with the nanoporous solid; and(iii) one or more pressure-inducing liquids.

2. The system of claim 1 , wherein the nanoporous solid has a pore size regime of from about 1 nm to about 1000 nm.

3. The system of claim 1 , wherein the nanoporous solid comprises metal-organic frameworks, zeolites, ceramics, activated carbon, silicates, polymeric materials, aerogels, pillared materials, inorganic porous hybrid materials or combinations thereof.

4. The system of claim 1 , wherein the aqueous fluid comprises deionized water.

5. The system of claim 1 , wherein a promotor present in the aqueous fluidpromoter mixture comprises tetrahydrofuran (THF), 1,3-dioxolane, cyclopentane, tetrahydrothiophene, argon, nitrogen or conbinations thereof.

6. The system of claim 1 , wherein a promoter present in the aqueous fluidpromoter mixture in an amount of from about 1 wt.% to about 20 et.% based on the total weight of the aqueous fluid-promoter mixture.

7. The system of claim 1 , wherein the pressure-inducing liquid creates a liquidliquid interface having an interfacial tension of equal to or greater than about 20 milliNewtons per meter (mN / m).

8. The system of claim 1 , wherein the pressure-inducing liquid comprises an aliphatic hydrocarbon and a surfactant.

9. The system of claim 8, wherein the aliphatic hydrocarbon comprises C3 to C20 aliphatic hydrocarbon.

10. The system of claim 8, wherein the aliphatic hydrocarbon comprises propane, iso-butane, n-butane, butane (n-butane ora mixture of linear and branched C4 acyclic aliphatic hydrocarbons), a mixture of linear and branched C5 acyclic aliphatic hydrocarbons), hexane (n-hexane or mixture of linear and branched Ce acyclic aliphatic hydrocarbons), heptane (n-heptane or mixture of linear and branched C7 acyclic aliphatic hydrocarbons), octane (n-octane, a mixture of linear and branched Cs acyclic aliphatic hydrocarbons), or combinations thereof.11 . The system of claim 1 , having a hydrogen storage capacity of from about 0.1 wt.% to about 5 wt.% based on the total weight of the system.

12. A method of storing hydrogen, comprising contacting a nanoporous solid with an aqueous fluid-promoter mixture under conditions suitable for the formation of a hydrated solid; , contacting the hydrated solid with at least one pressure-inducing liquid under conditions suitable for the formation of a hydrogen storage material; and contacting the hydrogen storage material with hydrogen.13 The method of claim 12, wherein the nanoporous solid comprises metalorganic frameworks, zeolites, ceramics, activated carbon, silicates, polymeric materials, aerogels, pillared materials, inorganic porous hybrid materials or combinations thereof.

14. The method of claim 12, wherein the nanoporous solid comprises silica.

15. The method of claim 12, wherein the aqueous fluid comprises deionized water.

16. The method of claim 12, wherein the promoter comprises tetrahydrofuran (THF), 1 ,3 -dioxolane, cyclopentane, tetrahydrothiophene, argon, nitrogen, or combinations thereof.

17. The method of claim 12, wherein the pressure-inducing liquid comprises an aliphatic hydrocarbon and a surfactant.

18. The method of claim 12, wherein the hydrogen storage material has a hydrogen storage capacity of from about 0.1 wt.% to about 5 wt.% based on the total weight of the hydrogen storage material.

19. The method of claim 12, further comprising charging the hydrogen storage material at a pressure ranging of from about 4 bar to about 12 bar.

20. The method of claim 12, further comprising charging the hydrogen storage material at a temperature ranging from about -40 °C to about 85 °C.

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