Hydrogen storage material and fuel cell containing same

Abstract

The present disclosure relates to a fuel cell including a fuel storage material made of a mesoporous N-doped carbon material. The fuel storage material includes a composite material including a proton-conducting polymer material, a scaffold of coalesced (N-doped) carbon nanofoam particles, and a coating on the scaffold, the coating comprising N-doped graphitic carbon. The fuel storage material allows fuel to be stored within the fuel cell and is typically incorporated adjacent to an electrode to supply fuel to the electrode when the fuel cell is operating in redox mode.

Description

[Technical Field]

[0001] The present disclosure relates to hydrogen storage materials for fuel cells, and in particular to fuel cells including hydrogen storage materials. In particular, the present disclosure relates to fuel cells configured to operate in both redox and regenerative modes. The present disclosure also relates to fuel cells having fuel storage materials integrated therein, and thus may include fuel cell-based energy storage devices. The present disclosure also relates to methods of forming the fuel storage materials. [Background technology]

[0002] Conventional electrochemical fuel cells convert fuel and oxidant into electrical energy and reaction products. The typical layout of a conventional fuel cell includes a solid polymer ion transport membrane sandwiched between an anode and a cathode. The polymer membrane allows protons to pass through the membrane but blocks the passage of electrons. Typically, both the anode and cathode are formed from an electrically conductive porous material, such as porous carbon, to which small particles of platinum and / or other precious metal catalysts are bonded.

[0003] The anode and cathode are typically formed on adjacent surfaces of the membrane, a combination commonly referred to as a membrane electrode assembly, or MEA.

[0004] Typically, the polymer membrane and porous electrode layers are sandwiched between flow plates. In conventional fuel cells, the flow plates deliver reactants to the anode and cathode and remove reaction products. Fuel cells can include porous gas diffusion layers fabricated to ensure efficient diffusion of gases to and from the anode and cathode surfaces and to assist in managing water vapor and liquid water.

[0005] Because the voltage produced by a single fuel cell is very low, multiple cells are typically connected in series, arranged so that the conductive flow plate on the cathode side of one cell is in electrical contact with the adjacent flow plate on the anode side of the next cell.

[0006] The present invention aims to provide improvements in the design of fuel cells and fuel cell stacks formed from such fuel cells.

[0007] The present disclosure relates to a composite material comprising a superstructure of coalesced (N-doped) carbon nanofoam particles coated with an N-doped graphitic carbon material, for particular use as a fuel storage material.

[0008] 1. A composite material comprising a superstructure of composite particles, the superstructure comprising: a scaffold of coalesced carbon nanofoam particles; a coating on the scaffold, said coating comprising N-doped graphitic carbon; and Including, The carbon nanofoam particles may optionally be N-doped.

[0009] According to a second aspect of the present disclosure, there is provided a fuel storage material comprising the composite material of the first aspect of the present disclosure and a proton-conducting polymer material.

[0010] According to a third aspect of the present disclosure, there is provided a fuel cell comprising the fuel storage material of the second aspect of the present disclosure as part of or adjacent to an electrode, and which, when operating in a redox mode, at least partially supplies said fuel to the electrode.

[0011] While the present disclosure is susceptible to various modifications and alternative forms, specifics of which are illustrated in the drawings and described in detail below. It should be understood, however, that other embodiments are possible aside from the specific embodiments described. All modifications, equivalents, and alternative embodiments falling within the spirit and scope of the appended claims are likewise embraced.

[0012] The above description is not intended to represent every embodiment or every implementation within the scope of the present or future claims. The following figures and detailed description also illustrate examples of various embodiments. Various example embodiments will be more fully understood by considering the following detailed description in conjunction with the accompanying drawings.

[0013] One or more embodiments will now be described, by way of example only, with reference to the accompanying drawings. [Brief explanation of the drawings]

[0014] [Figure 1] 1 illustrates an example embodiment of a fuel cell and schematically illustrates a fuel cell stack formed from such fuel cells. [Figure 2a] 1 shows an SEM micrograph of the N-doped carbon nanofoam material formed in Example 1. [Figure 2b] 1 shows an SEM micrograph of the N-doped carbon nanofoam material formed in Example 1. [Figure 3a] TEM micrographs of the composite materials are shown. [Figure 3b] TEM micrographs of the composite materials are shown. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present disclosure provides composite materials and fuel cells containing the composite materials in various configurations. The composite materials include a superstructure of composite particles, the superstructure including a scaffold of coalesced (N-doped) carbon nanofoam particles and a coating on the scaffold, the coating including N-doped graphitic carbon. The carbon nanofoam particle scaffold itself is optionally N-doped (also referred to as (N-doped) carbon nanofoam). The present disclosure also provides various examples of composite materials in different configurations that find various uses, particularly as fuel storage materials in fuel cells that can operate in conventional redox mode and regenerative mode. A particularly preferred type of (N-doped) carbon nanofoam material used in the examples of the present disclosure is described in more detail below.

[0016] An exemplary embodiment of a fuel cell is described.

[0017] In one or more embodiments, a fuel cell can be configured to operate in both a conventional redox mode, in which fuel and oxidant are consumed to produce electrical current and one or more reaction products, and a regenerative mode, in which an electrical potential difference is applied to the fuel cell and at least one of the one or more reaction products is electrolyzed to produce the fuel. Thus, one or more exemplary embodiments of a fuel cell include a reversible fuel cell. In one or more examples, one or more catalyst layers are provided to enable operation in the redox mode and the regenerative mode.

[0018] In one or more embodiments, a fuel cell can include a fuel storage material as a structure or layer in conjunction with, i.e., alongside, or forming part of, a fuel cell electrode, thereby providing a reservoir of fuel within the fuel cell. In one or more examples, a fuel storage material is provided between a first plate containing the active area of ​​the fuel cell and a second plate.

[0019] In one or more examples, the fuel is protons, and the fuel storage material is configured to store the fuel.

[0020] In one or more examples, the fuel storage material is electrically connected to the electrodes.

[0021] In one or more examples, the fuel storage material includes a composite material including a superstructure of composite particles, the superstructure comprising: a scaffold of coalesced (N-doped) carbon nanofoam particles; a coating on the scaffold, said coating comprising N-doped graphitic carbon; and and a proton conducting polymer material as described below.

[0022] It will be appreciated that a fuel cell may be configured to include the fuel storage material without being configured to operate in the redox mode and regeneration mode, for example, a fuel cell may be configured to operate only in the regeneration mode, thereby functioning to store fuel in the fuel storage material for extraction.

[0023] It will be appreciated that references to a "fuel cell" may also be understood to refer generally to a stack of fuel cells, given that the shape of a fuel cell is replicated throughout the stack.

[0024] 1 illustrates an exemplary fuel cell 100 according to one embodiment of the present disclosure. The fuel cell 100 includes a polymer electrolyte membrane, or "PEM," 101. The PEM 101 includes a semi-permeable membrane and can be configured to conduct protons while functioning as an electronic insulator and reactant barrier.

[0025] The first plate 104 is positioned adjacent, e.g., directly adjacent, to the first electrode 102. The second plate 105 is positioned adjacent, e.g., directly adjacent, to the second electrode 103. In one or more examples, the first plate includes channels (not shown in FIG. 1 ) formed in a surface 106 of the first plate that faces the first electrode 102. The channels can be configured to receive a fluid, such as an oxidant, from one or more fluid inlets (shown schematically at 107) and distribute the fluid across the surface of the first electrode 102.

[0026] Each plate 104, 105 may include a current tab 112, 113 through which electrical current flows during use.

[0027] The fuel cell 100 may include one or more first catalyst layers 114, 115 between the first plate 104 and the polymer electrolyte membrane 101. The one or more first catalyst layers may be configured to provide active sites for catalytic activity for one or both of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Suitable catalyst materials for use in the catalyst layers are described in more detail below.

[0028] In one or more examples, an OER catalyst layer may be provided on the side 114 of the first electrode facing the first plate 104. In one or more examples, an ORR catalyst layer may be provided on the side 115 of the first electrode facing the PEM 101.

[0029] In this example and one or more other examples, the first electrode 102 is porous, allowing fluid to pass through the electrode and reach the PEM 101 .

[0030] The fuel cell 100 may include one or more second catalyst layers 116, 117 between the second plate 105 and the polymer electrolyte membrane 101. The one or more second catalyst layers may be configured to provide active sites for catalytic activity for one or both of the hydrogen reduction reaction (HRR) and the hydrogen evolution reaction (HER).

[0031] In one or more examples, a HER catalyst layer can be provided on the side 116 of the second electrode facing the second plate 105. In one or more examples, a HRR catalyst layer can be provided on the side 117 of the second electrode facing the PEM 101.

[0032] Catalytic materials suitable for use as HER and HRR catalysts are described in detail below.

[0033] In this example and one or more examples, the fuel cell 100 is configured to operate in a redox mode and a regeneration mode. In the redox mode, the fuel cell 100 is configured such that a fuel is supplied to the second electrode 103 and an oxidant, such as oxygen from the air, is supplied to the first electrode 102, generating an electric current between the first electrode 102 and the second electrode 103 and generating a reaction product at the first electrode 102.

[0034] In a hydrogen-based fuel cell, the fuel comprises hydrogen, the oxidant comprises oxygen from air or an oxygen source, and the reaction product comprises water.

[0035] In regeneration mode, the fuel cell is configured so that a reaction product, such as water in the case of a hydrogen-based fuel cell, is supplied to the first electrode 102. A power source (not shown) provides a potential difference between the first electrode 102 and the second electrode 103, which causes the fuel, e.g., hydrogen, to be produced at the second electrode 103.

[0036] The fuel cell 100 may include a fuel storage material as part of or adjacent to the second electrode 103 to at least partially supply the fuel to the second electrode 103 in a redox mode and / or at least partially store the fuel produced at the second electrode 103 in a regeneration mode.

[0037] In this example or in one or more examples, the second electrode 103 is formed from the fuel storage material. Thus, the fuel storage material may be an integral part of the second electrode 103.

[0038] In other examples, the fuel storage material may comprise a layer separate from the second electrode 103, but is disposed adjacent to the second electrode 103 within the fuel cell 100, i.e., at least partially between the first plate 104 and the second plate 105.

[0039] In one or more examples, the PEM is bonded to a gas diffusion layer (such as a carbon-based conductor, e.g., carbon paper, carbon cloth, or carbon fiber, preferably carbon paper), and the other side of the gas diffusion layer is coated with a HER catalyst. This catalyst layer is adjacent to the anode and allows for the facile transfer of electrons.

[0040] This configuration has been found to be advantageous when the anode functions as a fuel storage material (e.g., the N-doped graphite-coated (N-doped) carbon nanofoam material and proton-conducting polymer material described herein). In such a configuration, hydrogen generated by the HER is also captured. It has been found that when the HER is directly coated on the anode, hot spots can occur, resulting in reduced efficiency of hydrogen storage.

[0041] In one or more embodiments, the fuel cell 100 is configured to be sandwiched between a first plate 104 and a second plate 105 and includes a peripheral gasket 120 that includes at least a polymer electrolyte membrane 101, a first electrode 102, a second electrode 103, one or more first catalyst layers, and one or more second catalyst layers. The gasket 120 can be made of silicone or vulcanized rubber. In other examples, the fuel cell 100 can be surrounded by a housing to contain the layers, reactants, and reaction products.

[0042] In one or more examples, fuel cell 100 may be part of a fuel cell stack 121 that includes multiple fuel cells arranged in series with one another. In Figure 1, box 122 schematically represents a fuel cell adjacent to fuel cell 100 in fuel cell stack 121. Adjacent fuel cell 122 is substantially identical to fuel cell 100.

[0043] 1 illustrates a fuel cell capable of operating in both redox and regenerative modes by having suitable catalyst layers and integrated fuel storage materials, although in one or more examples, only a portion of the above structure may be provided.

[0044] In one example, the fuel cell 100 may be configured to include the fuel storage material but operate only in a redox mode. Thus, in one or more examples, only the catalyst(s) that act to promote the redox reaction may be provided. In further examples, one or more first catalysts may not be provided, and one or more second catalysts may be provided. In such examples, the fuel storage material of the second electrode 103 may be "recharged" from an external fuel source rather than operating in a regeneration mode. Thus, during "recharge," hydrogen gas may be supplied to the second electrode 105 through the channels in the second plate 105, and one or more second catalyst layers 117, 116 may reduce the hydrogen gas to protons for storage in the fuel storage material.

[0045] In a further example, the fuel cell 100 may be configured to include the fuel storage material but operate only in a redox mode. The first and second catalyst layers function to improve the reaction rate of the fuel cell, but this may not be necessary in some applications. Thus, in one or more examples, the fuel cell 100 may include the fuel storage material but not one or more of the first and second catalyst layers 114, 115, 116, 117.

[0046] In a further example, the fuel cell 100 may be configured to operate only in regenerative mode, and thus, one or more first catalyst layers 114 may be provided, but one or more second catalyst layers 116, 117 may not be present.

[0047] Some specific materials that may be used in fuel cells are discussed in more detail below.

[0048] (N-doped) carbon nanofoam materials The present disclosure provides (N-doped) carbon nanofoam materials that have excellent properties as components of composite materials and fuel storage materials in fuel cells.

[0049] As used herein, the term "(N-doped)" (i.e., in parentheses) means that the material is optionally doped with N. Thus, "(N-doped) carbon nanofoam material" refers to a carbon nanofoam material that may be optionally N-doped.

[0050] As used herein, "C nf " may be used to refer to carbon nanofoam materials.

[0051] As used herein, "C nf -N x " may be used to represent N-doped carbon nanofoam material.

[0052] Carbon materials provide useful electrocatalysts due to their high surface area, high conductivity, and cost. Various types of carbon materials suitable for use as electrocatalysts are disclosed in X. Wang et al., Adv. Energy Mater., 2017, 7, 1700544.

[0053] Nonmetallic atoms such as N, P, S, and B can be doped into carbon structures, resulting in multiple possible configurations of doped carbon materials. These heteroatoms are more electronegative than carbon, making neighboring carbon atoms electron-deficient, thereby facilitating oxygen adsorption into carbon nanostructures. Doped carbon structures can take on a variety of morphologies, including nanotubes, sheets, and particulate carbon materials.

[0054] Among these doping atoms, N is advantageous because it provides a stable material with a desirable balance of properties. Furthermore, N doping improves the hydrogen storage properties of fuel storage materials comprising the disclosed carbon nanofoams. In contrast, doping with S and P typically acidifies the carbon, producing materials with greater pH sensitivity.

[0055] The (N-doped) carbon nanofoam material of the present disclosure may be characterized as a scaffold of coalesced (N-doped) carbon nanofoam particles, said particles having diameters between 0.005 μm and 25 μm.

[0056] Preferably, the nanofoam particles have a diameter of 0.01 to 15 μm, preferably 0.01 to 5 μm, more preferably 0.01 to 2 μm.

[0057] The diameter of the nanofoam particles can be measured by SEM. Typically, such a process measures the largest dimension of the particle.

[0058] The average diameter can be calculated by taking the average of the largest dimension measurements of 10 individual nanofoam particles.

[0059] The (N-doped) carbon nanofoam materials of the present disclosure are continuous or semi-continuous interconnected superstructures of coalesced (N-doped) carbon nanofoam particles, which can serve as a scaffold or support for the N-doped graphitic carbon in the composite materials of the present disclosure.

[0060] In one example, the scaffold has a tortuous path of open pores that is at least 3 times the average diameter of the nanofoam particles, preferably at least 5 times the average diameter of the nanofoam particles, for example 5 to 100 times, preferably 5 to 50 times the average diameter of the nanofoam particles.

[0061] Open pores are typically irregularly shaped, as shown in Figure 2b. Pore size can be determined by SEM, and the average size of a given pore is defined as the average of the largest and smallest dimensions of that pore as determined by SEM.

[0062] The average size of the pores in the scaffold will vary depending on the particle size of the nanofoam particles, and is typically between 10 and 100 μm, such as when the nanofoam particles are about 1 μm.

[0063] In an alternative embodiment, the average size of the pores in the scaffold is typically between 0.2 and 2 μm.

[0064] The average pore size can be determined by averaging 10 average pore sizes measured by SEM.

[0065] In one example, the density of the (N-doped) carbon nanofoam material is 300 mg / cm 3 Less than 50-200 mg / cm 3 , preferably 50 to 150 mg / cm 3 is.

[0066] The density of the (N-doped) carbon nanofoam material can be measured by weighing the bulk material and correlating the mass to the average elemental density.

[0067] Methods for producing carbon nanofoam are known in the art, for example as described in Sattler et al., Carbon 95 (2015), pp 434-441.

[0068] An example of a method for forming (N-doped) carbon nanofoam material is i. forming a mixture of sugar, water, and a hydrocarbon medium; ii. heating the mixture to form carbon nanofoam; iii. Optionally, heating the carbon nanofoam in the presence of an acidic nitrogen source (e.g., nitric acid) to form N-doped carbon nanofoam.

[0069] Sugars suitable for use include monosaccharides, disaccharides, trisaccharides, such as sucrose, glucose, or fructose, preferably sucrose.

[0070] The sugar and water mixture is highly concentrated, i.e., at least 3 molar, typically at least 4 molar, e.g., about 5 molar, and at such high concentrations, complete dissolution of the sugar typically requires heating to 50°C to 85°C, e.g., 60°C to 80°C, and vigorous stirring.

[0071] Typically, the concentrated sugar solution is cooled, for example to below 50° C., before adding the hydrocarbon vehicle.

[0072] Suitable hydrocarbon mediators include aromatic hydrocarbons such as pyrene, chrysene, benz[a]anthracene, fluoranthene, anthracene, naphthalene, benzene, hexane, and the like, with anthracene, naphthalene, and benzene being preferred, and naphthalene being most preferred.

[0073] Typically, only a small amount of hydrocarbon mediator (e.g., naphthalene) is required. For example, the ratio of hydrocarbon mediator (e.g., naphthalene) to sugar (e.g., sucrose) is typically 1:25,000 to 1:75,000, or 1:50,000 to 1:65,000.

[0074] Step ii involves heating the mixture to form the nanofoam. The mixture is heated at a temperature and for a time sufficient to carbonize the sugars and form a granular material.

[0075] Preferably, the mixture is heated at a temperature between 100°C and 600°C for 30 minutes to 24 hours. Heating to higher temperatures typically requires shorter heating times. For example, the mixture can be heated to 500°C for 1 hour. Alternatively, the mixture can be heated to 155°C for 5 hours. Of course, it is possible to heat the mixture for longer periods of time, but this is usually not necessary.

[0076] Preferably, the mixture is heated at a temperature of 350° C. to 600° C. for 30 minutes to 3 hours, or alternatively, the mixture is heated at a temperature of 100° C. to 300° C. for 4 minutes to 12 hours.

[0077] The heating step carbonizes the material to form nanofoam, and is therefore typically carried out in a suitably inert vessel such as a Teflon-coated hydrothermal reactor.

[0078] The heating step is preferably carried out in a closed reactor.

[0079] The resulting nanofoam may optionally be comminuted, for example by milling, which may be carried out in a ball mill.

[0080] The resulting material is a scaffold of coalesced (N-doped) carbon nanofoam particles. The (N-doped) carbon nanofoam particles are typically mesoporous, i.e., have pores between 2 nm and 50 nm. The nanofoam particles are covalently bonded together, resulting in a scaffold that retains its shape remarkably well even under mechanical stress, such as during milling.

[0081] The pore size of the mesopores can be measured by tunneling electron microscopy. In such a process, the material can be coated with a metal such as titanium by sputtering. After coating, the pore structure can be observed using a tunneling electron microscope, and the pore size can be determined from the image produced. While this method provides a surface image, it is clear from the reactivity of the entire material that the pores extend into the carbon structure below the surface. Therefore, this material is best described as a mesoporous (N-doped) carbon nanofoam.

[0082] The shape of the nanofoam particles can vary and can depend on the sugar and carbohydrate vehicle used, for example, glucose and naphthalene form cube-like structures.

[0083] Sucrose and naphthalene are preferred and produce roughly spherical particles.

[0084] The diameter of the nanofoam particles is typically 0.01 to 15 μm, preferably 0.01 to 5 μm, and more preferably 0.01 to 2 μm.

[0085] Step iii. involves N-doping the carbon nanoform by heating it with an acidic nitrogen source such as nitric acid (HNO), nitrous acid (HNO), hyponitrous acid (HNO), or mixtures thereof, with nitric acid being preferred.

[0086] Typically, the carbon nanofoam is heated to at least 80°C for at least 2 hours, such as at least 90°C for at least 4 hours, preferably 95°C to 115°C for at least 4 hours.

[0087] Heating is typically carried out in a suitable acid-resistant pressure vessel, such as a Teflon hydrothermal reactor.

[0088] To ensure a sufficient level of N doping, the acidic nitrogen source (e.g., nitric acid) needs to be sufficiently concentrated. Suitable concentrations (e.g., nitric acid) include 3 molar to 10 molar, preferably 4 molar to 8 molar.

[0089] Treating carbon nanofoam particles with nitric acid or an alternative acidic nitrogen source introduces N doping into the structure, forming a mixture of pyridinic N, pyrrolic N, and graphitic N sites. However, when nitric acid or an alternative acidic nitrogen source is used, the acidic conditions also result in the formation of additional carboxyl groups on the surface of the material. Furthermore, pitting corrosion can occur on the surface, potentially resulting in the loss of some of the mesoporous structure. Therefore, conditions must be controlled to achieve the desired amount of doping while avoiding excessive degradation of the mesoporous structure. However, the process is gentle enough to ensure that the scaffolding of the coalesced particles is maintained.

[0090] Typically, after treatment with nitric acid or an alternative acidic nitrogen source, the surface pore size increases by about 2-10%.

[0091] Typically, the N content of the obtained material is 0.1-8 wt%, for example 0.5-6 wt%, or 1-5 wt%. Preferably, the N content of the obtained substance is 2 wt% or more.

[0092] The surface area of ​​the resulting material is typically between 200 and 3500 m 2 / g, preferably 400 to 3000m 2 / g, preferably 800 to 2500m 2 / g, preferably 800 to 2000m 2 / g. For example, 900 to 2000 m 2 / g, preferably 900 to 1500m 2 / g.

[0093] The surface area can be measured, for example, by BET isotherm at 77 K using nitrogen.

[0094] The above process is an exemplary method for forming N-doped carbon nanofoam. Alternative methods are possible. For example, a mesoporous structure can be obtained by heating a mixture of sugar, water, and a hydrocarbon medium. If the mixture contains a nitrogen source, N-doped carbon nanofoam can be formed without the need for step iii (treatment with an acidic nitrogen source).

[0095] composite material The present disclosure optionally provides a composite material comprising a superstructure of composite particles, said superstructure comprising a scaffold of coalesced (N-doped) carbon nanofoam particles and a coating on the scaffold, said coating comprising N-doped graphitic carbon. The coalesced (N-doped) carbon nanofoam particle scaffold is as described above and may optionally itself be N-doped, for example, formed by treatment with an acidic nitrogen source such as nitric acid.

[0096] N-doped graphitic carbon coatings can be formed by treating a coalesced nanofoam particle scaffold with a structural protein and then coating the (N-doped) carbon nanofoam scaffold with N-doped graphitic carbon. This step can be performed on an (N-doped) carbon nanofoam particle scaffold (e.g., one formed after treatment with an acidic nitrogen source) or on a coalesced (N-doped) carbon nanofoam particle scaffold (i.e., one where the scaffold material is not N-doped).

[0097] During formation, the (N-doped) carbon nanofoam scaffold provides a template for the growth of the N-doped graphitic phase, which is typically located on the surfaces of the (N-doped) carbon nanofoam scaffold, such as on the outer and inner surfaces, within the open pores, etc.

[0098] The composite material typically retains the same overall structure as coalesced particles of the (N-doped) carbon nanofoam scaffold used as a template before coating with the N-doped graphitic carbon phase.

[0099] Thus, a composite material may be described as comprising composite particles.

[0100] Thus, the composite particles comprise a continuous or semi-continuous scaffold of (N-doped) carbon nanofoam coated with N-doped graphitic carbon. The N-doped graphitic phase is typically disposed on the surface of the (N-doped) carbon nanofoam scaffold, e.g., on the outer and inner surfaces, within the open pores, etc.

[0101] The composite particles are joined together via (N-doped) carbon nanofoam scaffolds to form the superstructure of the composite material, i.e., the (N-doped) carbon nanofoam scaffolds interconnect the composite particles to form the superstructure.

[0102] The coalesced superstructure of the composite particles may also include N-doped graphitic carbon on the available surface.

[0103] In the context of this disclosure, "N-doped graphitic carbon" refers to graphitic carbon containing nitrogen atoms within the graphite planes. These nitrogen atoms form graphite moieties (replacing carbon with three bonds, forming six-member rings), pyridine moieties (replacing carbon with two bonds, forming five-member rings), and pyrrole moieties (replacing carbon with two bonds, forming five-member rings) within the graphite planes. The pyridine and pyrrole moieties within the graphite planes reduce the number of atoms, resulting in defects or vacancies within the planes.

[0104] Preferably, the diameter of the composite particle is 0.005 μm to 25 μm. For example, the diameter of the composite particle is 0.01 to 15 μm, for example, 0.01 to 5 μm, or 0.01 to 2 μm.

[0105] Smaller particles are typically preferred because they have a much greater surface area.

[0106] Preferably, the diameter of the composite particle is 100 nm or less, for example, 50 nm or less, 30 nm or less, for example, 25 nm or less, 20 nm or less. Preferably, the diameter of the composite particle is 10 to 30 nm.

[0107] The composite particles tend to agglomerate to form clusters, which typically have diameters of 1 to 10 μm, for example 2 to 8 μm, or 3 to 6 μm.

[0108] For example, if the composite particles are about 20 nm, the aggregated clusters can have diameters of about 3-6 μm.

[0109] The diameter of composite particles and clusters can be measured by TEM. Typically, such processes measure the largest dimension of the particle / cluster.

[0110] The formation of the composite material typically involves: -Heating (N-doped) carbon nanofoam materials together with structural proteins in a low-oxygen environment Includes.

[0111] Thus, one example of a method for forming a composite material is a. forming a mixture of sugar, water, and a hydrocarbon medium; b. heating the mixture to form a carbon nanofoam material; c. optionally, heating the carbon nanoform with an acidic nitrogen source (e.g., nitric acid) to form N-doped carbon nanoform; d. Optionally, milling the (N-doped) carbon nanofoam material; and e. heating the (N-doped) carbon nanofoam material with a structural protein in a low-oxygen environment to form a composite material; f. optionally treating the composite material with a pitting agent to form an activated composite material; g. Optionally, grinding the composite material; and Includes.

[0112] Steps e. to g. may be repeated as necessary until the required amount of N-doped graphite area is obtained and the required active surface area is achieved.

[0113] Steps a., b., and c. are identical to steps i., ii., and iii. of the exemplary method for forming (N-doped) carbon nanofoam material.

[0114] Step d is optional, but is often performed to ensure a more consistent material is used as a scaffold for the formation of N-doped graphitic carbon. Suitable comminution methods include milling, such as ball milling.

[0115] Step e. involves heating the resulting nanofoam together with structural proteins in a low-oxygen environment to form an N-doped graphite coating on the (N-doped) carbon nanofoam.

[0116] The low-oxygen environment can be achieved by any means, preferably using an inert atmosphere (such as argon gas) or a vacuum.

[0117] The mixture is heated to a high temperature for a relatively short time. Longer heating at the temperature required to effect N doping is possible, but is usually not necessary.

[0118] Typically, step e. involves heating at a temperature of at least 400°C for at least 10 minutes, for example, at 450°C to 900°C for 10 minutes to 3 hours, preferably at 500°C to 600°C for 30 minutes to 90 minutes.

[0119] Heating at high temperatures, such as above 1000°C, graphitizes the structural proteins, forming large amounts of graphite. The low temperatures used in step e. result in partial graphitization.

[0120] The resulting material contains N-doped graphitic carbon coated on the (N-doped) carbon nanofoam, eg, on the exterior and interior surfaces, within the open pores, etc.

[0121] Optional step f. includes treating the resulting material with a pitting agent to form an activated composite material. In the context of the present disclosure, "pitting agent" refers to a substance that causes activation of the composite material, for example, by increasing the surface area. For example, step f. can create pits or depressions in the surface of the composite material, providing a larger active surface area.

[0122] The pitted composite may be referred to as an "activated composite."

[0123] Suitable pitting agents include alkali or alkaline earth metal carbonates, alkali or alkaline earth metal hydroxides, such as NaOH, KOH, Na2CO3, K2CO3, or mixtures thereof.

[0124] Alternatively, acidic pitting agents such as H2SO4, HCl, HNO3, H3PO4, and mixtures thereof may be used.

[0125] Preferably, the pitting agent is an alkali or alkaline earth carbonate. When an alkali or alkaline earth carbonate pitting agent is used, regular and consistent pitting is achieved. Typically, the alkali or alkaline earth carbonate pitting agent increases the number of mesopores in the material, and the mesopores have smooth or rounded edges. Rounded mesopores are particularly advantageous for hydrogen storage by physical adsorption.

[0126] In contrast, when an acidic pitting agent is used, the pitting is more random and the newly formed pits may have jagged edges and have irregular shapes.

[0127] Preferably, the pitting agent is K2CO3.

[0128] The pitting agent should be included in an amount sufficient to enhance surface activity, typically in excess (by weight). For example, the weight ratio of composite to pitting agent can be 1:1.5 or greater, e.g., 1:2 to 1:10, 1:2.5 to 1:8, or 1:3 to 1:5. Preferably, the weight ratio of composite to pitting agent is 1:3.

[0129] Step f. must be carried out in a low-oxygen environment at high temperatures, typically at a temperature of at least 600°C for at least 10 minutes, e.g., 650-1000°C for 10 minutes to 3 hours, and preferably 750-850°C for 1 hour.

[0130] Optional step g. can be performed by milling, which separates any loosely bound graphitic material, leaving a composite particle superstructure comprising a coalesced (N-doped) carbon nanofoam scaffold and a coating of N-doped graphite.

[0131] The N-doped graphitic material is preferably covalently bonded to the scaffold.

[0132] Typically, the N content of the obtained material is 0.1-8 wt%, for example 0.5-6 wt%, or 1-5 wt%. Preferably, the N content of the obtained substance is 2 wt% or more.

[0133] The surface area of ​​the resulting material is typically between 200 and 3500 m 2 / g, preferably 400 to 3000m 2 / g, preferably 800 to 2500m 2 / g, preferably 800 to 2000m 2 / g. For example, 900 to 2000 m 2 / g, preferably 900 to 1500m 2 / g.

[0134] When a pitting agent is used, the surface area of ​​the resulting material can be 25% to 50% higher than the surface area of ​​the same material before pitting. The amount of surface area increase depends on the amount / concentration of the pitting agent, the temperature at which the pitting is performed, the length of the pitting step, and the type of pitting agent used.

[0135] Any suitable structural protein may be used, such as keratin or collagen, although keratin is preferred. The structural protein should preferably be dry and in a form that allows it to be intimately mixed with the carbon particles, such as in powder form.

[0136] Suitable collagen materials that can be used include gelatin.

[0137] Any source of keratin can be used, including hair, nails, feathers, horns, talons, baleen, or hooves.

[0138] Preferably, the structural protein is bird feathers. Bird feathers are highly porous, and it has been found that the resulting material remains porous after carbonization to form an N-doped graphite coating.

[0139] Feathers from any suitable bird can be used, but farmed birds such as chickens, turkeys, ducks and geese are particularly suitable due to their ready availability.

[0140] Down feathers are preferred, especially goose down and duck down.

[0141] Typically, bird feathers are mixed with (N-doped) carbon nanofoam in a weight ratio of nanofoam to feathers of 2:1 to 1:4, preferably 3:2 to 1:3.

[0142] After formation of the coating layer, the resulting material can optionally be comminuted, for example by milling.

[0143] OER, ORR, HER, HRR catalyst materials Various types of catalytic materials are known for use in fuel cells. For example, X. Wang et al., Adv. Energy Mater., 2017, 7, 1700544 and C. Zhang et al., Front. Energy., 2017, 11, 268-285 and N. Alonso-Vante et al., Catalysts, 2018, 8, 559 provide an overview.

[0144] In some embodiments, bifunctional catalysts may be used in fuel cells. A bifunctional catalyst is a catalyst that has the ability to catalyze two different types of reactions.

[0145] In some cases, the ORR and OER can be catalyzed by the same bifunctional catalyst.

[0146] In some cases, OER and HER can be catalyzed by the same bifunctional catalyst.

[0147] When a bifunctional catalyst is used, heterojunctions can be used to separate positive and negative charges within the organic material.

[0148] Noble metal-based electrocatalysts (Pt, Ir, and Ru-based) are well known to catalyze ORR, OER, and HER reactions.

[0149] Platinum group metals are known to be used as electrocatalysts, with platinum being the most commonly used electrocatalyst. However, concerns about the durability of platinum in use around the world have led to research into new platinum group metal alloy nanoparticles supported on conductive substrates such as carbon, carbon black, oxides, single-walled carbon nanotubes, and carbon nanofibers.

[0150] Such platinum group metal alloys can be described as Pt-M (where M=3d transition metal) alloy nanoparticles, for example, where M is one or more of Ni, Co, Fe, Cu, Pd, Rh, Ti, V, Cr, Mo, W, and Re. For example, PtNi3, Pt x Co (where x = 2, 3, 5, 7, and 9), Pt3Cu, PtCu, and PtCu3.

[0151] In some cases, ternary Pt-based systems may also be suitable catalysts. For example, a catalyst may be described as Pt-MN, where M is as defined above and N is Fe, Cu, Ni, or Co. Examples include PtCuNi, PtCoNi, PtFeNi, and PtFeCo.

[0152] Transition metal-based catalysts are also known as electrocatalysts suitable for ORR, OER, and HER. For example, catalysts based on Ti, V, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, or mixtures thereof, such as Mn, Co, Ni, and Fe oxides.

[0153] Preferably, the transition metal is selected from Co, Fe, Ni, or mixtures thereof.

[0154] Preferably, the transition metal is Co.

[0155] Suitable cobalt-based catalysts include, but are not limited to, cobalt oxide, cobalt phosphide, cobalt halides, cobalt nitrate, cobalt chalcogenides (sulfides and selenides), Co-containing layered double hydroxides, Co-NC, Co-based single atoms, Co-MOFs (metal organic frameworks), cobalt carboxylates, Co-Nx / C, and composites thereof.

[0156] Fuel Storage Materials The present disclosure further provides a fuel storage material, particularly for use in a fuel cell, said fuel storage material comprising a proton conducting polymer material and a composite material comprising a superstructure of composite particles, said superstructure comprising: a scaffold of coalesced (N-doped) carbon nanofoam particles; a coating on the scaffold, wherein the coating comprises N-doped graphitic carbon.

[0157] The N-doped graphitic carbon coated (N-doped) carbon nanofoam material is preferably as described herein.

[0158] Proton conducting polymer materials are typically capable of conducting protons at room temperature, ie, 25°C.

[0159] "Able to conduct protons" means that the proton conductivity is 10 -3 S / cm, preferably above 10 -2 This means that the proton conductivity exceeds 1000 S / cm. Of course, the polymer itself may have a very low proton conductivity in the dry state. The proton conductivity of a polymer material is measured on a hydrated and (optionally) acidified polymer.

[0160] The proton conducting polymer material may be an acid doped hydrogel.

[0161] When an appropriate acid, such as phosphoric acid or sulfuric acid, is added to the hydrogel, the resulting polymeric material exhibits very high proton conductivity.

[0162] A suitable level of acid dopant in the hydrogel is 5-25% by weight, preferably 10-20% by weight.

[0163] Suitable hydrogels are selected from polyvinyl alcohol, poly(meth)acrylate, collagen, gelatin and fibrin.

[0164] Preferred hydrogel polymers are selected from poly(meth)acrylates and gelatin, with polyacrylates being particularly preferred.

[0165] The fuel storage material typically contains less than 15 wt %, preferably 0.1 to 12 wt %, more preferably 0.2 to 10 wt %, and even more preferably 0.5 to 8 wt % of the acid-doped hydrogel.

[0166] The proton conducting polymeric material may be a fluorinated acid polymer, preferably a fluorinated acid polymer as described herein.

[0167] Preferably, the fluorinated acid polymer in the fuel storage material has the formula X: [ka] wherein each c is independently 0 or an integer from 1 to 3; n is at least 4; R f 3 and R f 4 are independently selected from F, Cl, or highly fluorinated alkyl groups having 1 to 10 carbon atoms; a=0, 1, or 2, E 5 is selected from hydrogen or a cation such as Li, Na, or K.

[0168] Preferably, the fluorinated acid polymer in the fuel storage material has a perfluorocarbon backbone and a structure of the formula [ka] and a side chain represented by the formula: E 5 is selected from hydrogen or a cation such as Li, Na, or K.

[0169] Preferably, the fluorinated acid polymer in the fuel storage material is of Formula XI: [ka] wherein each c is independently 0 or an integer from 1 to 3; n is at least 4; E 5 is selected from hydrogen or a cation such as Li, Na, or K.

[0170] The fuel storage material typically contains less than 5 wt %, for example 0.05 to 5 wt %, preferably 0.1 to 4 wt %, more preferably 0.1 to 3 wt %, even more preferably 0.2 to 2 wt % of the fluorinated acid polymer.

[0171] In one example, a method for making a fuel storage material includes: forming a paste of a composite material, a proton conducting polymer material and a dispersant, said composite material comprising: forming a composite particle superstructure comprising a scaffold of coalesced (N-doped) carbon nanofoam particles and a coating on the scaffold, the coating comprising N-doped graphitic carbon; compressing the paste into a hardened form; drying the solidified form; and Includes.

[0172] Typically, the paste is formed using water as a dispersant.

[0173] When the proton conducting polymer material is an acid doped hydrogel, the forming step comprises: forming a mixture of a hydrogel-forming polymer, an acid dopant, and a composite material; freeze-drying the mixture; adding water to form a paste of the freeze-dried conductive polymer material and composite material; may include:

[0174] The freeze-drying step improves the structural integrity of the hydrogel, allowing it to maintain excellent proton conductivity when incorporated into fuel storage materials.

[0175] Typically, the drying step involves heating the solidified form at a temperature high enough to facilitate removal of the dispersant, but low enough so as not to damage the proton-conducting polymer material.

[0176] Suitable temperatures include 50 to 250° C., for example, when using a fluorinated acid polymer as the proton conducting material, 100 to 200° C. To facilitate removal of the dispersant, heating may be carried out in a flowing air stream.

[0177] When acid-doped hydrogels are used as proton-conducting materials, it is generally preferable to avoid high temperatures during the drying step, as these hydrogels tend to be less stable at high temperatures. Preferably, the drying step involves drying at a temperature of 75° C. or less.

[0178] Optionally, after drying, the material may be degassed, for example in a vacuum oven.

[0179] The fuel storage material may further include an Arrhenius acid to facilitate the absorption and storage of protons. While any Arrhenius acid may be used, suitable acids include sulfuric acid, phosphoric acid, and nitric acid. The Arrhenius acid added to the fuel cell is also referred to as a "polymer activator."

[0180] In the case of hydrogel-based proton conducting materials, the acid is preferably phosphoric acid.

[0181] In the case of fluorinated polymeric sulfonic acid based proton conducting materials, the acid is preferably sulfuric acid.

[0182] The material can be treated with an Arrhenius acid by immersing it in a solution of the acid for a sufficient period of time (eg, at least 4 hours).

[0183] Once loaded with acid, the material can be dried to remove most of the water, but to ensure sufficient proton conductivity, it is beneficial to maintain a low water content: residual water within the material aids in the transport and retention of hydrogen ions, which interact with water to form hydronium ions.

[0184] Typically, the fuel storage material contains at least 0.01 wt% water, preferably at least 0.1 wt% water, for example 0.01 to 5 wt% water, preferably 0.1 to 2 wt% water.

[0185] Without wishing to be bound by theory, the N-doped graphitic carbon phase promotes the chemisorption of hydronium ions within the fuel storage material, and the nitrogen sites (especially the pyridine and pyrrole sites) can hydrogen bond with the ions to immobilize them on the surface of the material.

[0186] "Hydronium ion" is protonated water, i.e., HO + The fuel storage material of the present disclosure is hydronium itself, or H5O2 + , H7O3 + , H9O4 + The solvated forms of hydronium, such as HCl, ...

[0187] Charge balance is believed to be achieved by negative charges stored in the graphite material, which is further facilitated and stabilized by the electronegativity of the nitrogen atoms and the high electrical conductivity of the material as a whole.

[0188] In an operating fuel cell, the released hydronium ions migrate to the PEM and protons pass through the PEM to the counter electrode, where they react with oxygen to form water.

[0189] Without wishing to be bound by theory, the fuel storage material also stores hydrogen through physical adsorption within the mesopores of the (N-doped) carbon nanofoam. Therefore, as the concentration of hydronium ions increases, it becomes less favorable to store additional hydrogen as hydronium while maintaining charge balance within the graphitic material. Instead, dihydrogen forms, which condenses within the mesopores of the (N-doped) carbon nanofoam when the pressure increases to a sufficient level (e.g., above about 5 bar). Within the mesopores, hydrogen is in a quasi-liquid state. The liquefied hydrogen is immobilized in the fuel storage material by physical adsorption onto the surfaces of the mesopores. While hydrogen liquefaction typically occurs at high pressures (e.g., 300 bar), the confined liquefaction within the mesopores of the (N-doped) carbon nanofoam facilitates liquefaction at much lower pressures (e.g., about 5 bar).

[0190] N-doping of carbon nanofoam further promotes physical adsorption because the electronegativity of the N atom promotes the formation of van der Waals interactions between hydrogen and N-doped carbon nanofoam. To enhance the hydrogen storage properties of fuel storage materials, it is beneficial to increase the number of mesopores in the carbon nanofoam as well as the degree of N-doping.

[0191] The primary hydrogen storage mechanism within a fuel storage material depends on the temperature and pressure of the system. Typically, chemisorption dominates when the pressure is below 5 bar and the temperature is typically below 80 °C, while physisorption dominates when the pressure is above 5 bar and the temperature is typically above 80 °C. However, it is common for hydrogen to be stored by both chemisorption and physisorption simultaneously.

[0192] Surprisingly, the fuel storage material is capable of storing hydrogen at levels greater than 1 wt%, such as greater than 1.5 wt%, or greater than 1.8 wt%, or even greater than 2 wt%.

[0193] Measurement Protocol Pore ​​size calculation To calculate the pore size at and below the micropore level, we used the protocol described by Kawazoe et al., J. Chem. Eng. Japan, 16(6), 1983, 470-475.

[0194] The above protocol describes how to calculate the effective pore size distribution from the adsorption isotherm. The pore size distribution was calculated from the N2 isotherm at 77 K.

[0195] To measure the N2 isotherm at liquid N2 temperature, a sample (approximately 0.3 g) was placed in a sample holder and heated at 200 °C for 10 min. -5 Torr (1.33x10 -3 The mixture was degassed for at least 48 hours at a pressure of 1.33 × 10 Pa. A Cahn electrobalance allowed for very accurate mass measurements. A ULVAC ionization vacuum gauge and an MKS Baratron sensor were used for pressure measurements (pressure range 1.33 × 10 -6 ~6.65×10 -1 Pa, 1.33 x 10 -1 ~10 5 Pa).

[0196] To calculate the pore volume above 1.5 nm, we used the following protocol: Dollimore, D. and GRHeal et al., J. AppL Chem., 14, 1964, 109-114.

[0197] The above protocol describes how to calculate pore size distributions from adsorption isotherms on porous solids.

[0198] Here, the total amount of nitrogen absorbed at a pressure of 1 atmosphere and a temperature of 77 K gives the total pore volume. In the cylindrical pore model, the total pore volume is: 1 / 4*pi*d*d*l, is calculated using the formula: d is the average pore diameter, l is the total pore length.

[0199] If the BET surface area measures the total surface area of ​​the pores, then the BET surface area S(BET) = pi * d * l. The l was eliminated from the two equations and the average diameter d was calculated.

[0200] The Barrett-Joyner-Halenda (BJH) method assumes capillary condensation of liquid nitrogen within the pores. The pore size distribution is calculated by taking into account the nitrogen adsorption layer and capillary condensation from the relative pressure of the adsorption isotherm and the amount of nitrogen absorbed at a given relative pressure. The adsorption and desorption branches lead to different pore size distributions. Therefore, the desorption branch is usually used.

[0201] surface area The samples were treated at elevated temperature (120 °C) and reduced pressure for at least 8 h before nitrogen adsorption to remove bound gases and adsorbed water from the material.

[0202] N2 adsorption analysis can be performed using a Belsorp Mini (Bel Japan, Inc.) apparatus at 77 K using liquid gas for each test, and the adsorption data is used to calculate the surface area using Brunauer-Emmett-Teller (BET) theory.

[0203] Density calculation of carbon nanofoam The following methods are used: Displacement density method: Using water as the displacement medium, the density is calculated using the formula D=m / v (mass ÷ volume) at 22°C and 1 atm pressure.

[0204] The TAP density method is explained by the following: The International Pharmacopoeia, s.3.6. Bulk Density and Tapped Density of Powders, QAS11_450 FINAL (revised March 2012). Tapped density is the increase in bulk density obtained after mechanically tapping a container containing a powder sample.

[0205] Here, tapped density is obtained by mechanically tapping a graduated cylinder containing the sample until there is little or no change in volume. Tapping can be done in a variety of ways. Tapped density is calculated by dividing the mass by the final volume of the powder.

[0206] The mean value of the two measurements was then calculated.

[0207] Conductivity of ground material samples Spin coating was used to prepare the material samples, which were prepared in the same way as the preparation steps for making electrodes: the silver foil was coated with the material sample in a solution and 5% binder was added.

[0208] If the resistance of the material sample was greater than or equal to a kilohm, a two-point probe was used.

[0209] The spin-coated film is placed in a metal sample holder and a vacuum is created inside to remove any moisture.

[0210] Two-point and four-point probe tests can be used.

[0211] The measured conductivity of the samples averaged between 0.4 S / cm and 100 S / cm, depending on the layer thickness and the conductivity of the carbon support used.

[0212] Preferences, options, and embodiments with respect to a given aspect, feature, or parameter of the present invention should be considered to be disclosed in combination with any preferences, options, and embodiments with respect to all other aspects, features, and parameters of the present disclosure, unless the context indicates otherwise. Embodiments and features of the present invention are also outlined in the following sections.

[0213] A1. A (N-doped) carbon nanofoam material comprising a scaffold of coalesced (N-doped) carbon nanofoam particles, preferably wherein said particles have a diameter between 0.005 μm and 25 μm.

[0214] A2. The (N-doped) carbon nanofoam material according to item A1, wherein the (N-doped) carbon nanofoam particles have a diameter of 0.01 to 15 μm.

[0215] A3. The (N-doped) carbon nanofoam material according to paragraph A1 or A2, wherein the (N-doped) carbon nanofoam particles have a diameter of 0.01 to 5 μm.

[0216] A4. The (N-doped) carbon nanofoam material according to any one of paragraphs A1 to A3, wherein the (N-doped) carbon nanofoam particles have a diameter of 0.01 to 2 μm.

[0217] A5. The (N-doped) carbon nanofoam material according to any one of paragraphs A1 to A4, wherein the (N-doped) carbon nanofoam particles are mesoporous.

[0218] A6. The (N-doped) carbon nanofoam material of any one of paragraphs A1-A5, wherein the material is a scaffold of coalesced (N-doped) carbon nanofoam particles, the scaffold having a tortuous path of open pores at least three times the average diameter of the nanofoam particles.

[0219] A7. The (N-doped) carbon nanofoam material according to any one of paragraphs A1 to A6, wherein the open pores of the scaffold have an average pore size of 10 to 100 μm.

[0220] A8. The (N-doped) carbon nanofoam material according to item A7, wherein the open pores of the scaffold have an average pore diameter of 0.2-2 μm.

[0221] A9. The material is 300 mg / cm 3The (N-doped) carbon nanofoam material of any one of paragraphs A1 to A8, having a density of less than

[0222] A10. The material is 50 to 200 mg / cm 3 The (N-doped) carbon nanofoam material according to item A9, having a density of

[0223] A11. The material is 50 to 150 mg / cm 3 The (N-doped) carbon nanofoam material according to item A10, having a density of

[0224] A12. The (N-doped) carbon nanofoam material according to any one of paragraphs A1 to A11, wherein the (N-doped) carbon nanofoam has an N content of 0.1 to 8 wt %.

[0225] A13. The (N-doped) carbon nanofoam material according to any one of paragraphs A1 to A12, wherein the (N-doped) carbon nanofoam has an N content of 1 to 5 wt %.

[0226] A14. The (N-doped) carbon nanofoam material according to any one of paragraphs A1 to A13, wherein the (N-doped) carbon nanofoam has an N content of 2 wt % or more.

[0227] A15. The (N-doped) carbon nanofoam has a viscosity of 400 to 3000 m 2 The (N-doped) carbon nanofoam material according to any one of paragraphs A1 to A14, having a surface area of ​​1 / g.

[0228] A16. The (N-doped) carbon nanofoam is 900-2000m 2 The (N-doped) carbon nanofoam material according to any one of paragraphs A1 to A14, having a surface area of ​​1 / g.

[0229] A17. The (N-doped) carbon nanofoam material has a viscosity of 900 to 1500 m 2 The (N-doped) carbon nanofoam material according to any one of paragraphs A1 to A14, having a surface area of ​​1 / g.

[0230] A18. The (N-doped) carbon nanofoam material according to any one of paragraphs A1 to A17, wherein the (N-doped) carbon nanofoam material is an N-doped carbon nanofoam material.

[0231] B1. A method for forming (N-doped) carbon nanofoam material, comprising: i. forming a mixture of sugar, water, and a hydrocarbon medium; ii. heating the mixture to form carbon nanofoam; iii. optionally, heating said carbon nanofoam in the presence of an acidic nitrogen source to form N-doped carbon nanofoam; A method comprising:

[0232] B2. The method of claim B1, wherein the sugar is one or more monosaccharides, disaccharides, and / or trisaccharides.

[0233] B3. The method according to claim B2, wherein the sugar is one or more of sucrose, glucose, or fructose.

[0234] B4. The method according to item B3, wherein the sugar is sucrose.

[0235] B5. The concentration of the sugar and water solution is at least 3 mol / dm 3 The method according to any one of items B1 to B4, wherein

[0236] B6. The concentration of the sugar and water solution is at least 4 mol / dm 3 The method according to any one of items B1 to B5, wherein

[0237] B7. The concentration of the sugar and water solution is at least 5 mol / dm 3 The method according to any one of items B1 to B6, wherein

[0238] B8. The method according to any one of items B1 to B7, wherein the solution is completely dissolved in water to form a mixture of sugar and water.

[0239] B9. The method according to item B8, wherein the sugar dissolves in water upon heating and vigorous stirring.

[0240] B10. The method according to item B9, wherein the sugar dissolves in water when the solution is heated to 50°C to 85°C.

[0241] B11. The method according to item B9, wherein the sugar dissolves in water when the solution is heated to 60°C to 80°C.

[0242] B12. The method of any one of paragraphs B5-B11, wherein the sugar and water solution is cooled before adding the hydrocarbon vehicle.

[0243] B13. The method of claim B12, wherein the sugar and water solution is cooled to below 50° C. before adding the hydrocarbon vehicle.

[0244] B14. The method according to any one of paragraphs B1 to B13, wherein the hydrocarbon medium is an aromatic hydrocarbon.

[0245] B15. The method according to item B14, wherein the aromatic hydrocarbon is pyrene.

[0246] B16. The method according to item B14, wherein the aromatic hydrocarbon is chrysene.

[0247] B17. The method according to item B14, wherein the aromatic hydrocarbon is benz[a]anthracene.

[0248] B18. The method according to item B14, wherein the aromatic hydrocarbon is fluoranthene.

[0249] B19. The method according to item B14, wherein the aromatic hydrocarbon is anthracene.

[0250] B20. The method according to item B14, wherein the aromatic hydrocarbon is naphthalene.

[0251] B21. The method according to item B14, wherein the aromatic hydrocarbon is benzene.

[0252] B22. The method according to item B14, wherein the aromatic hydrocarbon is hexane.

[0253] B23. The method according to any one of items B1 to B13, wherein the hydrocarbon intermediate is one or more of the aromatic hydrocarbons described in items B15 to B22.

[0254] B24. The method according to item B1, wherein the hydrocarbon medium is naphthalene and the sugar is sucrose.

[0255] B25. The method according to any one of paragraphs B1 to B24, wherein the ratio of carbohydrate vehicle to sugar is 1:25,000 to 1:75,000.

[0256] B26. The method according to any one of paragraphs B1 to B25, wherein the ratio of carbohydrate vehicle to sugar is 1:50,000 to 1:65,000.

[0257] B27. The method of any one of paragraphs B1-B26, wherein step ii is carried out at a temperature and for a time sufficient to carbonize the sugar to form a particulate material.

[0258] B28. The method according to item B27, wherein step ii is carried out at a temperature of 100°C to 600°C for 30 minutes to 24 hours.

[0259] B29. The method according to item B28, wherein step ii is carried out at a temperature of 350°C to 600°C for 30 minutes to 3 hours.

[0260] B30. The method according to item B29, wherein step ii is carried out at a temperature of 100°C to 300°C for 4 hours to 12 hours.

[0261] B31. The method according to any one of paragraphs B1 to B30, wherein step ii is carried out in an inert container.

[0262] B32. The method according to any one of paragraphs B1 to B31, wherein step ii is carried out in a closed reactor.

[0263] B33. The method according to any one of paragraphs B1 to B32, wherein the nanoform produced in step ii is milled.

[0264] B34. The method according to item B33, wherein the (N-doped) carbon nanofoam particles coalesce to form a scaffold.

[0265] B35. The method according to item B33 or B34, wherein said (N-doped) carbon nanofoam particles are mesoporous.

[0266] B36. The method according to any one of paragraphs B33 to B35, wherein the diameter of the carbon nanofoam particles formed in step ii is 0.1 to 25 μm.

[0267] B37. The method according to any one of paragraphs B33 to B36, wherein the diameter of the carbon nanofoam particles formed in step ii is 0.2 to 15 μm.

[0268] B38. The method according to any one of paragraphs B33 to B37, wherein the diameter of the carbon nanofoam particles formed in step ii is 0.5 to 5 μm.

[0269] B39. The method according to any one of paragraphs B33 to B38, wherein the diameter of the carbon nanofoam particles formed in step ii is 0.5 to 2 μm.

[0270] B40. The method of any one of paragraphs B1 to B39, wherein the carbon nanofoam in step iii is heated to at least 80° C. for at least 2 hours.

[0271] B41. The method of any one of paragraphs B1 to B40, wherein the carbon nanofoam in step iii is heated to at least 90° C. for at least 4 hours.

[0272] B42. The method of any one of paragraphs B1 to B41, wherein the carbon nanofoam in step iii is heated to 95°C to 115°C for at least 4 hours.

[0273] B43. The method according to any one of paragraphs B1 to B42, wherein step iii) is carried out in a suitable acid-resistant pressure vessel.

[0274] B44. The method according to any one of items B1 to B43, wherein the acidic nitrogen source is nitric acid.

[0275] B45. Nitric acid is used in step iii, the concentration is 3 mol / dm 3 ~10 mol / dm 3 The method according to item B44, wherein

[0276] B46. Nitric acid is used in step iii, the concentration is 4 mol / dm 3 ~8 mol / dm 3 The method according to item B44, wherein

[0277] B47. The method according to any one of paragraphs B1 to B46, wherein the (N-doped) carbon nanofoam has an N content of 0.1 to 8 wt. %.

[0278] B48. The method according to any one of paragraphs B1 to B47, wherein the (N-doped) carbon nanofoam has an N content of 1 to 5 wt. %.

[0279] B49. The method according to any one of paragraphs B1 to B48, wherein the (N-doped) carbon nanofoam has an N content of 2% by weight or more.

[0280] B50. The (N-doped) carbon nanofoam has a viscosity of 400 to 3000 m 2The method according to any one of items B1 to B49, having a surface area of ​​ / g.

[0281] B51. The (N-doped) carbon nanofoam is 900 to 2000 m 2 The method according to any one of items B1 to B50, having a surface area of ​​ / g.

[0282] B52. The (N-doped) carbon nanofoam is 900 to 1500 m 2 The method according to any one of items B1 to B51, having a surface area of ​​ / g.

[0283] B53. (N-doped) carbon nanofoam material obtained by the method of items B1 to B52.

[0284] C1. A composite material comprising a superstructure of composite particles, said superstructure comprising: a scaffold of coalesced (N-doped) carbon nanofoam particles; a coating on the scaffold, wherein the coating comprises N-doped graphitic carbon. Composite material.

[0285] C2. The composite material according to item C1, wherein the composite particles have a diameter of 0.005 to 25 μm.

[0286] C3. The composite material according to item C1 or C2, wherein the composite particles have a diameter of 0.01 to 15 μm.

[0287] C4. The composite material according to any one of items C1 to C3, wherein the composite particles have a diameter of 0.01 to 2 μm.

[0288] C5. The composite material according to any one of items C1 to C4, wherein the composite particles have a diameter of 100 nm or less.

[0289] C6. The composite material according to any one of items C1 to C5, wherein the composite particles have a diameter of 10 to 30 nm.

[0290] C7. The composite material according to any one of items C1 to C6, wherein the composite particles are aggregated into clusters of 1 to 10 μm.

[0291] C8. The composite material of any one of items C1 to C7, wherein the composite particles aggregate into clusters of 2 to 8 μm.

[0292] C9. The composite material of any one of paragraphs C1 to C8, wherein the composite particles aggregate into clusters of 3 to 6 μm.

[0293] C10. The composite material according to any one of paragraphs C1 to C9, wherein the (N-doped) carbon nanofoam particles are mesoporous.

[0294] C11. The composite material of any one of paragraphs C1 to C10, wherein the (N-doped) carbon nanofoam particles are N-doped.

[0295] C12. The composite material of any one of items C1 to C11, wherein the N-doped graphitic carbon coating is formed by treating an (N-doped) carbon nanofoam with a structural protein and coating the nanofoam with N-doped graphitic carbon.

[0296] C13. The composite material according to any one of items C1 to C12, wherein the material has N-doped graphitic domains located in the open pores of the scaffold of coalesced (N-doped) carbon nanofoam particles.

[0297] C14. The composite material of any one of items C1 to C13, wherein the N-doped graphitic carbon is covalently bonded to a (N-doped) carbon nanofoam scaffold.

[0298] C15. The composite material according to any one of items C1 to C14, wherein the N content in the material is 0.1 to 8 wt%.

[0299] C16. The composite material according to any one of items C1 to C15, wherein the N content in the material is 1 to 5 wt%.

[0300] C17. The composite material according to any one of items C1 to C16, wherein the N content in the material is 2% by weight or more.

[0301] D1. A method for producing a composite material by heating an (N-doped) carbon nanofoam material (preferably an (N-doped) carbon nanofoam material according to any one of paragraphs A1 to A18) together with a structural protein in a low oxygen environment.

[0302] D2. A method of forming a composite material, comprising: a. forming a mixture of sugar, water, and a hydrocarbon medium; b. heating the mixture to form a carbon nanofoam material; c. optionally, heating the carbon nanofoam in the presence of an acidic nitrogen source (such as nitric acid) to form N-doped carbon nanofoam; d. Optionally, milling the (N-doped) carbon nanofoam material; and e. heating the (N-doped) carbon nanofoam material with a structural protein in a low-oxygen environment to form a composite material; f. optionally treating the composite material with a pitting agent to form an activated composite material; g. Optionally, grinding the material; and A method comprising:

[0303] D3. The method according to item D2, wherein steps (e)-(g) can be repeated as necessary until the required amount of N-doped graphite region is obtained.

[0304] D4. The method according to item D2 or D3, wherein steps (a), (b) and (c) are the same as steps (i), (ii) and (iii) of any of items B1 to B51.

[0305] D5. The method according to any one of paragraphs D2 to D4, wherein the grinding steps (d) and / or (f) are carried out by milling.

[0306] D6. The method according to any one of items D2 to D5, wherein step (e) forms N-doped graphitic carbon covalently bonded to said (N-doped) carbon nanofoam.

[0307] D7. The method according to any one of items D1 to D6, wherein the low-oxygen environment is achieved by using an inert atmosphere (such as argon gas).

[0308] D8. The method according to any one of items D1 to D7, wherein the low oxygen environment is achieved by using a vacuum.

[0309] The method according to any one of paragraphs D1 to D8, wherein in step D9, the (N-doped) carbon nanofoam material is heated to a temperature of at least 400° C. for at least 10 minutes.

[0310] D10. The method according to any one of paragraphs D1 to D9, wherein the (N-doped) carbon nanofoam material is heated to a temperature of at least 450°C to 900°C for 10 minutes to 3 hours.

[0311] D11. The method of any one of paragraphs D1 to D10, wherein the (N-doped) carbon nanofoam material is heated to a temperature of at least 500°C to 600°C for 30 to 90 minutes.

[0312] D12. The method according to any one of items D9-D10, wherein the obtained material contains N-doped graphitic carbon.

[0313] D13. The method of any one of paragraphs D1-D12, wherein the structural protein is dried and in a form that allows it to be intimately mixed with the carbon particles.

[0314] D14. The method of D13, wherein the structural protein is in powder form.

[0315] D15. The method according to any one of items D1 to D14, wherein the structural protein is collagen.

[0316] D16. The method according to item D15, wherein the source of collagen is gelatin.

[0317] D17. The method according to any one of paragraphs D1 to D14, wherein the structural protein is keratin.

[0318] D18. The method according to item D17, wherein the source of keratin is hair.

[0319] D19. The method according to item D17, wherein the source of keratin is nails.

[0320] D20. The method according to item D17, wherein the source of the keratin is feathers.

[0321] D21. The method according to item D17, wherein the source of keratin is horn.

[0322] D22. The method according to item D17, wherein the source of keratin is claws.

[0323] D23. The method according to item D17, wherein the source of the keratin is whalebone.

[0324] D24. The method according to item D17, wherein the source of the keratin is hoof.

[0325] D25. The method according to item D20, wherein the feathers are bird feathers.

[0326] D26. The method according to item D25, wherein the bird feathers are farmed bird feathers.

[0327] D27. The method according to item D25, wherein the bird feathers are chicken feathers.

[0328] D28. The method according to item D25, wherein the bird feathers are turkey feathers.

[0329] D29. The method according to item D25, wherein the bird feathers are duck feathers.

[0330] D30. The method according to item D25, wherein the bird feathers are goose feathers.

[0331] D31. The method according to item D25, wherein the bird feathers are down feathers.

[0332] D32. The method according to item D31, wherein the fluff is goose fluff.

[0333] D33. The method according to item D31, wherein the fluff is duck fluff.

[0334] D34. The method according to any one of items D25 to D33, wherein the ratio of bird feathers to (N-doped) carbon nanofoam is a weight ratio of nanofoam to feathers of 2:1 to 1:4.

[0335] D35. The method according to any one of items D25 to D33, wherein the ratio of bird feathers to (N-doped) carbon nanofoam is between 3:2 and 1:3 by weight of nanofoam to feathers.

[0336] D36. The method according to any one of items D1 to D33, wherein step f. is carried out in a hypoxic environment.

[0337] D37. The method of any one of items D1 to D36, wherein step f. is carried out at a temperature of at least 600° C. for at least 10 minutes.

[0338] D38. The method according to any one of items D37, wherein step f. is carried out at 650 to 1000°C for 10 minutes to 3 hours.

[0339] D39. The method of any one of items D37 or D38, wherein step f. is carried out at 750-850°C for 1 hour.

[0340] D40. The method of any one of paragraphs D1-D39, wherein the weight ratio of composite material:pitting agent is 1:1.5 or greater.

[0341] D41. The method according to any one of items D1 to D40, wherein the weight ratio of the composite material to the pitting agent is 1:2 to 1:10, for example, 1:2.5 to 1:8, or 1:3 to 1:5.

[0342] D42. The method of any one of paragraphs D1-D40, wherein the weight ratio of composite material:pitting agent is 1:3.

[0343] D43. The method according to any one of items D1 to D42, wherein the pitting agent is potassium carbonate (K2CO3).

[0344] D44. A composite material obtainable by the method according to any one of items D1 to D43.

[0345] E1. Fuel storage materials, (i) a proton-conducting polymer material; (ii) a composite material comprising a superstructure of composite particles, said superstructure comprising: a scaffold of coalesced (N-doped) carbon nanofoam particles; a coating on the scaffold, wherein the coating comprises N-doped graphitic carbon. Fuel storage materials.

[0346] E2. The fuel storage material according to claim E1, wherein the composite material is as described in any one of claims C1-C17 or D44.

[0347] E3. The fuel storage material according to paragraphs E1 or E2, wherein the proton-conducting polymer material is capable of conducting protons at room temperature, i.e., 25°C.

[0348] E4. The fuel storage material of any one of paragraphs E1-E3, wherein the proton-conducting polymer material is an acid-doped hydrogel.

[0349] E5. The fuel storage material of claim E4, wherein the hydrogel is doped with phosphoric acid.

[0350] E6. The fuel storage material of item E4, wherein the hydrogel is doped with sulfuric acid.

[0351] E7. The fuel storage material according to any one of paragraphs E4 to E6, wherein the acid dopant in the hydrogel is 5 to 25% by weight.

[0352] E8. The fuel storage material according to any one of items E4 to E7, wherein the acid dopant in the hydrogel is 10 to 20% by weight.

[0353] E9. The fuel storage material of any one of paragraphs E4 to E8, wherein the hydrogel is polyvinyl alcohol.

[0354] E10. The fuel storage material of any one of paragraphs E4-E8, wherein the hydrogel is a poly(meth)acrylate.

[0355] E11. The fuel storage material of any one of paragraphs E4 to E8, wherein the hydrogel is collagen.

[0356] E12. The fuel storage material according to any one of paragraphs E4 to E8, wherein the hydrogel is gelatin.

[0357] E13. The fuel storage material of any one of paragraphs E4 to E8, wherein the hydrogel is fibrin.

[0358] E14. The fuel storage material of any one of paragraphs E4-E13, wherein the fuel storage material contains less than 15% by weight of an acid-doped hydrogel.

[0359] E15. The fuel storage material according to any one of paragraphs E4 to E14, wherein the fuel storage material typically contains 4 to 12 wt. % of the acid-doped hydrogel.

[0360] E16. The fuel storage material according to any one of paragraphs E4 to E15, wherein the fuel storage material typically contains 5 to 10 wt. % of the acid-doped hydrogel.

[0361] E17. The fuel storage material of any one of paragraphs E1-E3, wherein the polymeric material is a fluorinated acid polymer.

[0362] E18. The fuel storage material according to item E17, wherein the acidic groups are directly attached to side chains on the polymer backbone.

[0363] E19. The fuel storage material according to item E17 or E18, wherein the acidic groups are selected from carboxylic acid groups, sulfonic acid groups, sulfonimide groups, phosphoric acid groups, phosphonic acid groups, and combinations thereof.

[0364] E20. The fuel storage material according to any one of items E17-E19, wherein the acidic groups are selected from the group consisting of sulfonic acid groups, sulfonimide groups, and combinations thereof.

[0365] E21. The fuel storage material of any one of paragraphs E17-E20, wherein at least about 50% of the total number of halogen and hydrogen atoms in the polymer are fluorine atoms.

[0366] E22. The fuel storage material according to any one of paragraphs E17-E21, wherein at least about 75% of the total number of halogen and hydrogen atoms in the polymer are fluorine atoms.

[0367] E23. The fuel storage material according to any one of paragraphs E17 to E22, wherein at least about 90% of the total number of halogen and hydrogen atoms in the polymer are fluorine atoms.

[0368] E24. The fuel storage material according to any one of items E17 to E23, wherein the fluorinated acid polymer is perfluorinated.

[0369] E25. The fuel storage material according to any one of paragraphs E17 to E24, wherein the polymer backbone is selected from polyolefins, polyacrylates, polymethacrylates, polyimides, polyamides, polyaramids, polyacrylamides, polystyrenes, and copolymers thereof.

[0370] E26. The fuel storage material according to any one of items E17 to E25, wherein the acidic group is a sulfonic acid group.

[0371] E27. The fuel storage material according to any one of paragraphs E17 to E25, wherein the acidic group is a sulfonimide group.

[0372] E28. The sulfonimide group has the following formula: -SO2-NH-SO2-R The fuel storage material according to item E27, having the formula: wherein R is an alkyl group.

[0373] E29. The fuel storage material according to item E17, wherein the acidic group is on a fluorinated side chain.

[0374] E30. The fuel storage material according to item E29, wherein the fluorinated side chains are selected from alkyl groups, alkoxy groups, amide groups, ether groups, and combinations thereof.

[0375] E31. The fuel storage material of any one of paragraphs E17-E30, wherein the fluorinated acid polymer has a highly fluorinated olefin backbone with pendant highly fluorinated alkyl sulfonate, highly fluorinated ether sulfonate, highly fluorinated ester sulfonate, or highly fluorinated ether sulfonimide groups.

[0376] E32. The fuel storage material according to any one of paragraphs E17-E31, wherein the fluorinated acid polymer is a perfluoroolefin having perfluoroether sulfonic acid side chains.

[0377] E33. The fuel storage material according to item E17, wherein the polymer is a copolymer of 1,1-difluoroethylene and 2-(1,1-difluoro-2-(trifluoromethyl)allyloxy)-1,1,2,2-tetrafluoroethanesulfonic acid.

[0378] E34. The fuel storage material according to item E17, wherein the polymer is a copolymer of ethylene and 2-(2-(1,2,2-trifluorovinyloxy)-1,1,2,3,3,3-hexafluoropropoxy)-1,1,2,2-tetrafluoroethanesulfonic acid.

[0379] E35. The fuel storage material according to item E17, wherein the polymer is a homopolymer or copolymer of a fluorinated, partially sulfonated poly(arylene ether sulfone).

[0380] E36. The fluorinated acid polymer has Formula VII: [ka] is a sulfonimide polymer having the formula: R f is selected from highly fluorinated alkylenes, highly fluorinated heteroalkylenes, highly fluorinated arylenes, and highly fluorinated heteroarylenes, optionally substituted with one or more ether oxygens; The fuel storage material according to item E17, wherein n is at least 4.

[0381] Fuel storage materials according to item E36, where E37.n is greater than 10.

[0382] E38. The fluorinated acid polymer has formula XI: [ka] wherein each c is independently 0 or an integer from 1 to 3; n is at least 4; E 5 is selected from hydrogen or a cation such as Li, Na, or K.

[0383] E39. The fuel storage material according to item E17, wherein the fluorinated acid polymer also includes repeat units derived from at least one highly fluorinated ethylenically unsaturated compound.

[0384] E40. The fluorinated acid polymer has the formula: [ka] and a side chain, wherein R f 3 and R f 4 are independently selected from F, Cl, or highly fluorinated alkyl groups having 1 to 10 carbon atoms; a=0, 1, or 2, E 5 is selected from hydrogen or a cation such as Li, Na, or K.

[0385] E41. The fluorinated acid polymer comprises a perfluorocarbon backbone and a fluorinated acid polymer of the formula: [ka] and a side chain represented by the formula: E 5 is selected from hydrogen or a cation such as Li, Na, or K.

[0386] E42. The fuel storage material according to any one of items E17 to E41, wherein the material contains less than 5% by weight of a fluorinated acid polymer.

[0387] E43. The fuel storage material according to any one of paragraphs E17 to E42, wherein the material contains 0.1 to 5% by weight of a fluorinated acid polymer.

[0388] E44. The fuel storage material according to any one of paragraphs E17 to E43, wherein the material contains 0.3 to 4 wt. % of a fluorinated acid polymer.

[0389] E45. The fuel storage material according to any one of paragraphs E17 to E44, wherein the material contains 0.5 to 3% by weight of a fluorinated acid polymer.

[0390] E46. The fuel storage material of any one of paragraphs E1-E45, wherein the material further comprises an Arrhenius acid.

[0391] E47. The fuel storage material according to item E46, wherein the Arrhenius acid is sulfuric acid, phosphoric acid, or nitric acid.

[0392] E48. The fuel storage material according to item E46, wherein when the proton conducting material is a hydrogel, the Arrhenius acid is phosphoric acid.

[0393] E49. The fuel storage material according to item E47, wherein when the proton conducting material is a fluorinated polymeric sulfonic acid based material, the Arrhenius acid is sulfuric acid.

[0394] E50. The fuel storage material of any one of paragraphs E1-E49, wherein the fuel storage material is capable of storing hydrogen at levels greater than 1% by weight.

[0395] E51. The fuel storage material of any one of paragraphs E1-E50, wherein the fuel storage material is capable of storing more than 2% hydrogen by weight.

[0396] F1. A method for producing a fuel storage material, comprising: (i) forming a paste of a composite material, a proton conducting polymer material, and a dispersant, said composite material comprising a superstructure of composite particles, said superstructure comprising: a scaffold of coalesced (N-doped) carbon nanofoam particles; a coating on the scaffold, wherein the coating comprises N-doped graphitic carbon. Forming and (ii) compressing the paste into a solid form; (iii) drying the solidified form; A method comprising:

[0397] F2. The method of F1, wherein the paste is formed using water as a dispersant.

[0398] F3. The method of any one of items F1 to F2, wherein the polymeric material is an acid-doped hydrogel.

[0399] F4. Step (i) (a) forming a mixture of a hydrogel-forming polymer, an acid dopant, and a composite material; (b) freeze-drying the mixture; (c) adding water to form a paste of the freeze-dried conductive polymer material and the composite material; The method according to item F3, comprising:

[0400] F5. The method of any one of paragraphs F1-F4, wherein step (iii) comprises heating the solidified form at a temperature high enough to facilitate removal of the dispersing agent, but low enough so as not to damage the proton-conducting polymer material.

[0401] F6. The method of any one of paragraphs F1-F5, wherein the proton conducting material is a fluorinated acid polymer.

[0402] F7. The method according to item F6, wherein step (iii) comprises heating the solidified form at a temperature of 50 to 250°C.

[0403] F8. The method according to item F7, wherein step (iii) comprises heating the solidified form at a temperature of 100 to 200°C.

[0404] F9. The method of any one of items F7 to F8, wherein the heating is performed in a flowing air stream to facilitate removal of the dispersant.

[0405] F10. The method according to any one of items F1 to F5, wherein the proton-conducting material is an acid-doped hydrogel.

[0406] F11. The method of claim F10, wherein step (iii) comprises heating the solidified form at a temperature of 75°C or less.

[0407] F12. The method of any one of paragraphs F1-F11, wherein after step (iii), the material may be degassed.

[0408] F13. The method of any one of paragraphs F1-F12, wherein after step (iii), the material can be degassed in a vacuum furnace.

[0409] F14. The method of any one of items F1 to F13, wherein the composite material is as described in any one of items C1 to C17 or D44.

[0410] F15. The method of claim F1, wherein the formed fuel storage material is according to any one of claims E1 to E51.

[0411] F16. A fuel storage material obtainable by the method according to any one of items F1 to F15.

[0412] G1. A fuel cell comprising the fuel storage material of any one of paragraphs E1-E51 or F16.

[0413] G2. The fuel cell of claim G1, wherein the fuel storage material is part of or adjacent to an electrode and at least partially supplies the fuel to the electrode when operating in a redox mode.

[0414] G3. A fuel cell (100), a polymer electrolyte membrane (101) having a first electrode (102) on one side and a second electrode (103) on the other side, said polymer electrolyte membrane (101), said first electrode (102) and said second electrode (103) being disposed between a first plate (104) and a second plate (105); a polymer electrolyte membrane (101), wherein the first plate (104) is disposed adjacent to the first electrode (102) and the second plate (105) is disposed adjacent to the second electrode (105), the first plate optionally at least partially facing the first electrode (102) and defining a flow path configured to supply a fluid to the first electrode (102) and receive a fluid from the first electrode (102); one or more first catalyst layers between the first plate (104) and the polymer electrolyte membrane (101); one or more second catalyst layers between the second plate (105) and the polymer electrolyte membrane (101); Including, the fuel cell is configured to operate in a redox mode and a regenerative mode; In the redox mode, the fuel cell is configured such that fuel is supplied to the second electrode (103) and oxygen is supplied to the first electrode (102), and a current and reaction products are generated between the first electrode and the second electrode; In the regeneration mode, the fuel cell is configured to provide the reaction products to the first electrode (102) and a potential difference between the first electrode and the second electrode, thereby producing the fuel at the second electrode (103); the fuel cell includes a fuel storage material at or adjacent to the second electrode (103) to at least partially supply the fuel to the second electrode (103) in the redox mode and / or store the fuel in the regeneration mode; The fuel storage material comprises: a composite material and a proton conducting polymer material, the composite material including a superstructure of composite particles, the superstructure including: a scaffold of coalesced (N-doped) carbon nanofoam particles; a coating on the scaffold, wherein the coating comprises N-doped graphitic carbon. Fuel cells (100).

[0415] G4. The fuel cell of any one of paragraphs G1-G3, wherein the proton-conducting polymer material is a fluorinated acid polymer.

[0416] G5. The fuel cell according to item G4, wherein the material contains 0.1 to 5 wt. % of a fluorinated acid polymer.

[0417] G6. The fuel cell according to any one of paragraphs G1 to G3, wherein the proton-conducting polymer material is an acid-doped hydrogel.

[0418] G7. The fuel cell according to item G6, wherein the fuel storage material typically contains 4 to 12 wt. % acid-doped hydrogel.

[0419] G8. The fuel cell of any one of paragraphs G1-G7, wherein the material further comprises an Arrhenius acid.

[0420] G9. Each Diffusion of fuel into and / or out of the channels of said second plate; Diffusion of oxygen, e.g., from air, into and / or out of the channels of the first plate; Diffusion of fuel or its derivatives into and / or out of the membrane; and diffusion of fuel or its derivatives into and / or out of the membrane; The fuel cell according to any one of items G1-G8, further comprising one or more gas diffusion layers each configured to promote one or more of:

[0421] G10. The fuel cell according to item G9, wherein the gas diffusion layer has a hydrophobic coating.

[0422] G11. The fuel cell of any one of items G1 to G10, wherein the first electrode comprises carbon cloth.

[0423] G12. The fuel cell of any one of paragraphs G1-G11, wherein the first electrode comprises carbon paper.

[0424] G13. The fuel cell of any one of paragraphs G1 to G12, wherein the first electrode comprises a metal frit.

[0425] G14. The fuel cell according to item G9, wherein the gas diffusion layer comprises a porous structure of fibers or open-cell foam.

[0426] G15. The first plate and the second plate at least partially contain the fuel, oxygen, and reaction products in the fuel cell, and a rigid element that provides structural support to the first electrode, the membrane, and the second electrode; a conductive element for electrically coupling to the first electrode and the second electrode and for coupling to a circuit that transports electrons between the electrodes; a structure in which the first flow path and the second flow path are formed; The fuel cell according to any one of items G1 to G14, including none, one, or more of the above.

[0427] G16. The fuel cell of any one of items G1 to G15, wherein the fuel cell comprises a first electrode and a second electrode separated by a polymer electrolyte membrane, and the fuel storage material is disposed adjacent to or as part of the second electrode.

[0428] G17. A fuel cell stack comprising a plurality of fuel cells arranged in series, the plurality of fuel cells including at least one fuel cell according to any one of items G1 to G16.

[0429] G18. The fuel cell according to item G17, wherein the fuel cell stack does not include any cooling elements.

[0430] G19. The fuel cell of any one of paragraphs G1-G18, wherein the catalyst on the one or more first catalyst layers catalyzes OER and / or ORR reactions.

[0431] G20. The fuel cell described in any one of items G1 to G19, wherein the second plate includes a flow channel formed in a surface facing the second electrode and is configured to supply fluid to and receive fluid from the second electrode.

[0432] G21. The fuel cell according to any one of items G1 to G20, wherein the fuel cell comprises a gas diffusion layer between the polymer electrolyte membrane (101) and the second electrode (103).

[0433] G22. The fuel cell according to item G21, wherein the gas diffusion layer has a hydrophobic coating.

[0434] G23. The fuel cell according to item G21 or item G22, wherein the gas diffusion layer comprises a porous structure of fibers or open-cell foam.

[0435] G24. The fuel cell of any one of items G1 to G23, wherein the fuel cell is configured to receive hydrogen as fuel through the flow channels of the second plate.

[0436] G25. The fuel cell according to any one of items G1 to G24, wherein the fuel cell comprises a hydrogen fuel cell, the fuel comprises hydrogen, the oxidant comprises air, and the reaction product comprises water.

[0437] G26. The fuel cell of any one of items G1 to G25, wherein the first electrode comprises a woven layer of conductive fibers.

[0438] G27. The fuel cell according to item G26, wherein the fibers of the woven layer comprise a metal.

[0439] G28. The fuel cell according to items G26-G27, wherein the fibrous layer comprises a non-platinum group metal.

[0440] G29. The fuel cell according to item G28, wherein the fibrous layer comprises a nonwoven fabric.

[0441] G30. The first plate and the second plate at least partially contain the fuel, oxygen, and reaction products in the fuel cell, and a rigid element that provides structural support to the first electrode, the membrane, and the second electrode; a conductive element for electrically coupling to the first electrode and the second electrode and for coupling to a circuit that transports electrons between the electrodes; The fuel cell according to any one of items G1 to G29, which does not include either a structure in which the first flow path and the second flow path are formed, or includes one or more of these.

[0442] G31. The fuel cell of any one of items G1-G30, wherein the fuel cell is configured to be sandwiched between the first plate and the second plate and includes a peripheral gasket including at least the polymer electrolyte membrane, the first electrode, the second electrode, the one or more first catalyst layers, and the one or more second catalyst layers.

[0443] G32. A fuel cell stack comprising a plurality of fuel cells arranged in series, the plurality of fuel cells including at least one fuel cell according to any one of items G1 to G31.

[0444] H1. Use of a fuel storage material according to any of items E1 to E51 or F16 in a fuel cell.

[0445] H2. Use of a fuel storage material according to any of items E1 to E51 or F16 for storing hydrogen.

[0446] H3. The use according to item H2, wherein the hydrogen is in the form of a hydronium ion.

[0447] H4. The use according to item H3, wherein the hydrogen is stored by chemisorption.

[0448] H5. The use according to item H2, wherein the hydrogen is in liquefied hydrogen form.

[0449] H6. The use according to item H5, wherein the hydrogen is stored by physical adsorption.

[0450] H7. The use according to item H2, wherein the hydrogen is in the form of hydronium ions and liquefied hydrogen.

[0451] H8. The use according to item H7, wherein the hydrogen is stored by physical and chemical adsorption. [Example]

[0452] Example 1 - Preparation of N-doped carbon nanofoam 171 g of sugar was dissolved in 100 ml of deionized water (DI water). The mixture was heated and stirred until the sugar was completely dissolved. The final temperature was approximately 60°C to 80°C.

[0453] The mixture was allowed to cool to about 45° C. and 3 mg of naphthalene was added. The mixture was stirred to dissolve the naphthalene.

[0454] The resulting mixture was added to a Teflon-lined hydrothermal reactor, which was sealed and placed in an oven at 155°C for 5 hours.

[0455] The resulting mixture was allowed to cool, and the carbonaceous material was removed and thoroughly washed using physical dissolution, decantation, and DI filtering of the material in that order. The filtrate was dried under vacuum in an oven at 50 °C for 6-12 hours.

[0456] The material was then ground in a ball mill using 5mm-10mm steel bearings (other bearings such as alumina or zirconium could also be used) for at least 24 hours, and then sieved through a 43-63 micron polyamide filter.

[0457] The resulting material was nitrogen-doped by treatment with 6 M HNO3 at 100 °C for 8 h, then neutralized using a mild sodium bicarbonate solution and washed with DI water until the pH reached 6.5–7. The material was then dried under vacuum at 50 °C for 6–12 h.

[0458] SEM micrographs of the resulting material are shown in Figures 2a and 2b. The material is a scaffold of small particulate material, approximately 1-2 μm in diameter, which coalesce to form the foamed porous material.

[0459] Example 2 - Preparation of N-doped graphitic carbon coated carbon nanofoam material (composite material)

[0460] 171 g of sugar was dissolved in 100 ml of deionized water (DI water). The mixture was heated and stirred until the sugar was completely dissolved. The final temperature was approximately 60°C to 80°C.

[0461] The mixture was allowed to cool to about 45° C. and 3 mg of naphthalene was added. The mixture was stirred to dissolve the naphthalene.

[0462] The mixture was added to a Teflon-lined hydrothermal reactor, which was sealed and heated in an oven at 69°C for 5 hours.

[0463] The material was nitrogen-doped by mixing it with goose down in a 50:50 ratio (carbon material and feathers), and the mixture was heated to 550 °C for 1 hour in a low-oxygen environment (under argon flow).

[0464] Once the composite was formed, a pitting agent (K2CO3) was added to the mixture in a composite to pitting agent mass ratio of 1:3. The material was then dried and heated at 800 °C for 1 h under a nitrogen atmosphere.

[0465] Once complete, the mixture was cooled and the carbonaceous material was removed. The material was thoroughly washed using physical dissolution, decantation, and DI filtering, in that order. The filtrate was dried under vacuum in an oven at 50°C for 6-12 hours.

[0466] The material was then ground in a ball mill using 5mm-10mm steel bearings (other bearings such as alumina or zirconium could also be used) for 12 hours and then sieved through a 43-63 micron polyamide filter.

[0467] Optionally, the washing and grinding can be repeated to produce the final product.

[0468] TEM micrographs of the resulting material are shown in Figures 3a and 3b. The material is a superstructure of small particulate material, approximately 10-30 nm in diameter, which aggregate to form clusters of approximately 4-5 μm, as shown in Figures 3a and 3b, respectively.

[0469] To disperse the aggregates and image the individual particles, an ionic solvent, such as isopropyl alcohol, is added to the sample.

[0470] Example 3 - Fuel Storage Material 20 ml of deionized water was added to 100 g of the composite material from Example 2. 1 wt % of the 60% EtOH Nafion® 212 solution was added to the carbon nanofoam solution. The materials were mixed with a paddle to ensure uniform dispersion.

[0471] The solution was solidified into a sheet 2-3 mm thick (depending on the effective surface area of ​​the final battery model). The electrode sheet was then exposed to a stream of dehumidified dry air at 150°C for 2 minutes. Infrared heating was used as the heating mechanism.

[0472] Next, the preheated electrode sheet was sent to a vacuum furnace and treated at 70°C and 101 kPa for 6 hours to degas the material.

[0473] After degassing the material, the sheets were immersed in 1M H2SO4 for 8-12 hours. After the immersion step, the material was allowed to dry at room temperature for 24 hours to allow excess water to evaporate, but not completely remove the moisture. It is estimated that a water content of at least 5000 ppm is required for proton conductivity.

[0474] The material is then cut to the required shape.

[0475] Example 4 - Estimation of storage capacity The hydrogen storage capacity of N-doped carbon nanofoam, including N-doped graphitic carbon (composite), was estimated from the discharge time of a fuel cell containing the composite in the fuel storage electrode. The results were compared with those of other known carbon nanofoam materials. [Table 1] Table 1. Details of fuel storage materials A to E

[0476] To form the electrodes, each material was combined with Nafion® 212 (5–10%) and soaked in 1 M H2SO4 to activate the Nafion. The amount of fuel storage material in each test cell was normalized to 1 g. Test battery dimensions: 3cm x 3cm Effective surface area: 9cm 2 Catalyst: Pt-C, 20% platinum on carbon (purchased from fuelcellstore: 20% platinum on Vulcan XC 72, product code: 591278) Polymer activator: 1M H2SO4 PEM: Nafion® 115 Fuel: 10mL of water Accurate time: 1 minute ·Load: 100mA

[0477] Table 2 shows the discharge times for each carbon nanofoam material. Storage materials D and E show significantly longer discharge times than materials A, B, and C. This indicates that materials D and E have higher hydrogen storage capacities, with material E having the best performance.

[0478] Without wishing to be bound by theory, it is believed that materials D and E have better hydrogen storage capabilities due to their larger surface area and higher degree of N-doping, which facilitates the absorption of the hydronium form of hydrogen. For example, hydrogen can be absorbed by the hydronium form of HO. + , H5O2 + , or H9O3 + It can be stored as [Table 2] Table 2. Discharge times for fuel storage materials A to E

[0479] Based on the discharge time, samples D and E are estimated to store approximately 1-2% hydrogen.

Claims

1. 1. A fuel cell comprising a fuel storage material, the fuel storage material comprising: (i) a proton-conducting polymer material; and (ii) a composite material comprising a superstructure of composite particles, said superstructure comprising: a scaffold of coalesced carbon nanofoam particles; a coating on the scaffold, the coating comprising N-doped graphitic carbon; The carbon nanofoam particles may optionally be N-doped. fuel cell.

2. 10. The fuel cell of claim 1, wherein the fuel storage material is part of or adjacent to an electrode and at least partially supplies the fuel to the electrode when operating in a redox mode.

3. 10. A fuel cell according to any one of the preceding claims, wherein the composite material comprises composite particles, the composite particles having a diameter of 0.005 to 25 μm.

4. 10. A fuel cell according to any one of the preceding claims, wherein the N-doped graphitic carbon is covalently bonded to the (N-doped) carbon nanofoam scaffold.

5. 10. A fuel cell according to any one of the preceding claims, wherein the (N-doped) carbon nanofoam particles are N-doped carbon nanofoam particles.

6. 10. The fuel cell according to any one of the preceding claims, wherein the composite material has an N content of 1-5 wt%.

7. 10. A fuel cell according to any one of the preceding claims, wherein the scaffold of coalesced (N-doped) carbon nanofoam particles has a tortuous path of open pores at least three times the average diameter of the nanofoam particles.

8. 8. The fuel cell of claim 7, wherein the composite material has N-doped graphitic domains located in the open pores of the scaffold of coalesced (N-doped) carbon nanofoam particles.

9. The composite material has a thickness of 900 to 2000 m ２ 10. A fuel cell according to any one of the preceding claims, having a surface area of ​​1000 W / g.

10. 10. A fuel cell according to any one of the preceding claims, wherein the proton conducting polymer material is an acid doped hydrogel.

11. The fuel cell according to any one of claims 1 to 9, wherein the polymer material is a fluorinated acid polymer.

12. A fuel cell stack comprising a plurality of fuel cells arranged in series, said plurality of fuel cells including at least one fuel cell according to any one of claims 1 to 11.

13. 12. A method for producing a composite material according to any one of claims 1 to 11, said method comprising: a. forming a mixture of sugar, water, and a carbohydrate medium; b. heating the mixture to form a carbon nanofoam material; c. Optionally, heating the carbon nanofoam in the presence of an acidic nitrogen source (such as nitric acid) to form N-doped carbon nanofoam; d. Optionally, milling the (N-doped) carbon nanofoam material; e. Heating the (N-doped) carbon nanofoam material together with structural proteins in a low oxygen environment to form a composite material; f. Optionally, treating the composite material with a pitting agent to form an activated composite material; g. Optionally, grinding the material; A method comprising:

14. 14. The method of claim 13, wherein the structural protein is collagen, gelatin or keratin, preferably the structural protein is feather, more preferably the structural protein is bird feather.

15. 1. A composite material comprising a superstructure of composite particles, the superstructure comprising: a scaffold of coalesced (N-doped) carbon nanofoam particles; a coating on the scaffold, wherein the coating comprises N-doped graphitic carbon.

16. 16. The composite material of claim 15, wherein the N-doped graphitic carbon is covalently bonded to the (N-doped) carbon nanofoam scaffold.

17. 17. A composite material according to claim 15 or claim 16, wherein the (N-doped) carbon nanofoam particles are N-doped.

18. The composite material according to any one of claims 15 to 17, wherein the N content in the material is 2% by weight or more.

19. (i) a proton-conducting polymer material; and (ii) a composite material according to any one of claims 15 to 18; and 2. A fuel storage material comprising:

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