Porous water-splitting catalyst based on textile material and method for its preparation

Abstract

The present invention relates to a porous water-splitting catalyst based on a textile material and a method for preparing the same, and the porous water-splitting catalyst based on a textile material according to the present invention includes: a porous textile support (10) formed by the intercrossing of a plurality of fibers (11); a bonding layer (20) formed on the surface of the fibers (11); a conductive layer (30) including a nanoparticle layer (31) including metal nanoparticles and formed on the bonding layer (20), and a monomolecular layer (33) including an amine group (NH2)-containing monomolecular material and formed on the nanoparticle layer (31); and a catalyst layer (40) containing a catalytic metal and formed on the conductive layer (30) by electroplating of the catalytic metal.

Description

TECHNICAL FIELD

[0001] The present invention relates to a fabric-based porous water-splitting catalyst and a method for preparing the same. More particularly, the present invention relates to a fabric-based porous water-splitting catalyst coated with a catalyst material through a simple electroplating process and a method for preparing the same. BACKGROUND

[0002] With the progress of industrial development, fossil fuels such as coal, oil, and natural gas have been depleted and cause environmental pollution and global warming. Therefore, there is a need to develop an energy source having potential to replace fossil fuels. In these circumstances, considerable research efforts have been made worldwide to develop alternative energy technologies including technologies for converting natural energy such as solar energy, wind energy, and tidal energy into electrical energy and technologies for producing hydrogen energy from natural resources such as water. In particular, hydrogen is produced from water, which is one of the most abundant resources on earth, as a raw material, and is a clean energy that does not release pollutants upon combustion. In addition, hydrogen produces more energy per unit weight than any other energy. Due to these advantages, hydrogen is attracting attention as a next-generation energy source. Hydrogen is generally produced by reforming under high-temperature and high-pressure conditions. However, hydrogen gas production by reforming emits carbon dioxide, which is environmentally unfriendly. Due to this disadvantage, many research groups have focused on a more efficient water-splitting method.

[0003] Only when a water-splitting catalyst has high performance for both an oxygen evolution reaction and a hydrogen evolution reaction in the same electrolyte, its overall high performance for water splitting can be expected. When water is catalytically split, intermediates repeatedly attach to and detach from the surface of the catalyst, which represents the activation energy of the catalyst. Therefore, abundant active sites on the catalyst surface and fast charge transfer are important for efficient hydrogen production.

[0004] Platinum (Pt) for a cathode and iridium (Ir) and ruthenium (Ru) for an anode are mainly used as catalyst materials for water splitting. These metals are produced and used in the form of nanoparticles or powders to secure a large surface area. However, since the produced metal nanoparticles or powders are difficult to use, they are blended with carbon black and a Nafion polymer and dropped on glass carbon before use. In addition, metals are expensive, and the low hygroscopicity of carbon black affects the contact area between the catalytic active sites and the electrolyte. The insulating material Nafion reduces charge transfer, ultimately leading to degradation of catalytic performance.

[0005] Therefore, there is an urgent need for a solution to address the problems of conventional water-splitting catalysts. SUMMARY

[0006] TECHNICAL PROBLEM

[0007] The present invention is directed to solving the problems of the prior art, and an aspect of the present invention is to provide a fabric-based porous water-splitting catalyst in which a metal is uniformly coated on the surface of fibers constituting a porous insulating fabric support by electroplating, and a method for preparing the water-splitting catalyst.

[0008] Technical Solution

[0009] The fabric-based porous water-splitting catalyst according to one embodiment of the present invention includes: a porous fabric support made by interweaving a plurality of fibers; a binding layer formed on the surface of the fibers; a conductive layer including a nanoparticle layer including metal nanoparticles and formed on the binding layer, and a monolayer including an amine group (NH2)-containing monomolecular material and formed on the nanoparticle layer; and a catalyst layer including a catalytic metal and formed by electroplating the catalytic metal on the conductive layer.

[0010] The fibers can be selected from the group consisting of cellulose fibers, polyester fibers, nylon fibers, acrylic fibers, and mixtures thereof.

[0011] The binding layer can include a polymer material containing an amine group (NH2).

[0012] The polymer material can be selected from the group consisting of polyethyleneimine (PEI), poly(allylamine hydrochloride) (PAH), and mixtures thereof.

[0013] The metal nanoparticles can be nanoparticles of one or more metals selected from the group consisting of Au, Ag, Al, Cu, and Pt.

[0014] The monomolecular material can be selected from the group consisting of tris(2-aminoethyl)amine (TREN), propane-1,2,3-triamine, diethylenetriamine (DETA), tetra(aminomethyl)methane, methane tetraamine, and mixtures thereof.

[0015] The conductive layer can be provided in a plurality, and the plurality of conductive layers can be stacked together.

[0016] The sheet resistance of the conductive layer can be 10 0 Ω / sq to 10 4 Ω / sq.

[0017] The catalytic metal can be selected from the group consisting of Ni, Co, Fe, Mo, Au, Ag, Cu, Cr, Ti, and alloys thereof.

[0018] The catalyst layer can include: a metal layer including the catalytic metal; and a hydroxide layer including a hydroxide of the catalytic metal and formed on the metal layer.

[0019] The catalytic metal present in the metal layer can be different from the catalytic metal of the catalytic metal hydroxide.

[0020] The method for preparing a fabric-based porous water-splitting catalyst according to one embodiment of the present application includes: (a) preparing a first dispersion of a polymer material, and immersing a porous fabric support made by interweaving a plurality of fibers into the first dispersion to form a binding layer on the surfaces of the fibers; (b) preparing a second dispersion of metal nanoparticles, and immersing the fabric support on which the binding layer is formed into the second dispersion to form a nanoparticle layer; (c) preparing a third dispersion of an amine group-containing monomolecular material, and immersing the fabric support on which the nanoparticle layer is formed into the third dispersion to form a monomolecular layer; and (d) electroplating a catalytic metal to form a catalyst layer on the monomolecular layer.

[0021] Steps (b) and (c) can be sequentially repeated at least twice before step (d) to form at least two conductive layers stacked together, each of the at least two conductive layers including a nanoparticle layer and a monomolecular layer stacked on the nanoparticle layer.

[0022] Step (d) can include: electroplating a catalytic metal to form a metal layer; and immersing the metal layer into an alkaline solution to form a hydroxide layer.

[0023] The features and advantages of the present application will become apparent from the following description with reference to the accompanying drawings.

[0024] Before describing the present application in detail, it is to be understood that the terminology and phraseology used herein are not to be interpreted literally and literally, but are intended to convey a general understanding of the present application. It is further understood that combinations of features, concepts and / or functions from one aspect of the present application can be applied to another aspect of the present application, unless explicitly stated to the contrary.

[0025] Advantageous effects

[0026] According to the present application, the metal is uniformly coated on all fiber strands constituting the porous insulating fabric structure by electroplating, ensuring excellent charge transport properties of the water-splitting catalyst and the conductivity of the water-splitting catalyst equivalent to that of the metal.

[0027] In addition, the fabric structure maintains its porosity to provide a large surface area. Therefore, the electrolyte easily penetrates into the fabric structure, and hydrogen and oxygen produced as a result of water splitting easily escape through the fabric structure, thereby achieving high performance of the water-splitting catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a cross-sectional view of a fabric-based porous water-splitting catalyst according to a first embodiment of the present application.

[0029] Figure 2is a partial cross-sectional view of a fabric-based porous water-splitting catalyst according to a first embodiment of the present invention.

[0030] Figure 3 is a cross-sectional view of a fabric-based porous water-splitting catalyst according to a second embodiment of the present invention.

[0031] Figure 4 is a cross-sectional view of a fabric-based porous water-splitting catalyst according to a third embodiment of the present invention.

[0032] Figure 5 and Figure 6 is a cross-sectional view of a fabric-based porous water-splitting catalyst according to a fourth embodiment of the present invention.

[0033] Figure 7 and Figure 8 is a flowchart and a diagram, respectively, showing a method for preparing a fabric-based porous water-splitting catalyst according to one embodiment of the present invention.

[0034] Figure 9 shows the change in the sheet resistance of the fabric-based porous water-splitting catalyst prepared in the Examples with an increase in the number (n) of conductive layers stacked in the catalyst.

[0035] Figures 10a to 10c is a scanning electron microscope (SEM) image of the fabric-based porous water-splitting catalyst prepared in the Examples.

[0036] Figures 11a to 11c shows the results of the evaluation of the activity of the fabric-based porous water-splitting catalyst prepared in the Examples for the hydrogen evolution reaction.

[0037] Figure 12 shows the results of the evaluation of the activity of the fabric-based porous water-splitting catalyst prepared in the Examples for the oxygen evolution reaction.

[0038] Figure 13a and Figure 13b shows the results of the evaluation of the activity of the fabric-based porous water-splitting catalyst prepared in the Examples for the hydrogen evolution reaction and the oxygen evolution reaction. DETAILED DESCRIPTION

[0039] Other objects, advantages and novel features of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, identical or similar reference signs generally indicate identical or similar components throughout the several views, even though the components depicted in the different drawings can be shown not identically or similarly. Although the terms such as "first" and "second" can be used to describe various elements, the elements should not be limited by the above terms. The terms are only used to distinguish one element from another element. In the description of the present application, the detailed description of related technology is omitted when it is considered that the detailed description of related technology can unnecessarily obscure the essence of the present application.

[0040] Preferred embodiments of the present application will now be described in detail with reference to the accompanying drawings.

[0041] Figure 1 is a cross-sectional view of a fabric-based porous water-splitting catalyst according to a first embodiment of the present application, and Figure 2 is a partial cross-sectional view of a fabric-based porous water-splitting catalyst according to the first embodiment of the present application.

[0042] As shown in Figure 1 and Figure 2 A fabric-based porous water-splitting catalyst according to the first embodiment of the present application includes: a porous fabric support 10 made by interweaving a plurality of fibers 11; a binding layer 20 formed on a surface of the fiber 11; a conductive layer 30 including a nanoparticle layer 31 including metal nanoparticles and formed on the binding layer 20, and a monomolecular layer 33 including an amine group (NH2)-containing monomolecular material and formed on the nanoparticle layer 31; and a catalyst layer 40 including a catalytic metal and formed by electroplating the catalytic metal on the conductive layer 30.

[0043] The present application relates to a fabric-based porous water-splitting catalyst. Conventional water-splitting catalysts use expensive metals, have a small contact area between catalytic active sites and electrolytes, and suffer from poor charge transfer. The present application is made in view of the problems of conventional water-splitting catalysts.

[0044] The fabric-based porous water-splitting catalyst of the present application includes a fabric support 10, a binding layer 20, a conductive layer 30, and a catalyst layer 40.

[0045] The fabric support 10 is a substrate made by interlacing multiple fibers 11 and has a plurality of pores formed between the fibers 11. The constituent fibers 11 of the porous fabric support 10 are elongated linear objects. The fibers 11 can include both natural fibers 11 and synthetic fibers 11. That is, the fabric support 10 can be made by spinning and weaving natural fibers 11, synthetic fibers 11, or blends thereof. The fibers 11 can be selected from, but are not limited to, cellulose fibers, polyester fibers, nylon fibers, acrylic fibers, and blends thereof. The fibers are not limited to a specific type, as long as they are interlaced to form a fabric support 10 of a predetermined shape.

[0046] Multiple fibers 11 are typically woven into a fabric support 10. However, the scope of the invention is not limited to weaving, and any technique for forming the fabric support 10 in two-dimensional or three-dimensional shapes can be used. Examples of such techniques include those for manufacturing ordinary paper or traditional Korean paper (“Hanji”) by dispersing the fibers 11 in water to cause the fibers to become thinly entangled. The fabric support 10 made of fibers 11 has a plurality of pores extending from its outer surface to its interior. Depending on the type of fibers 11, the fabric support 10 may be non-conductive. The fabric support 10 supports a conductive layer 30 and a catalyst layer 40. The conductive layer 30 is bonded to the fabric support 10 via a bonding layer 20.

[0047] The bonding layer 20 is formed by adsorbing a polymer material onto the fabric support 10. The polymer material allows for the coating of metal nanoparticles onto the fabric support 10 to form a nanoparticle layer 31, which will be described below. The polymer material can not only adsorb onto the surface of the fabric support 10 (i.e., the outer fibers 11 exposed on the outside), but also permeate into the fabric support 10 through its pores and adsorb onto the outer surface of the inner fibers 11, such as… Figure 2 As shown in the diagram, the polymer material may contain amine groups (NH2) that have a strong affinity for metal nanoparticles. For example, the polymer material may be selected from, but is not limited to, polyethyleneimine (PEI), poly(allylamine hydrochloride) (PAH), and mixtures thereof. There are no particular limitations on the polymer material, as long as it can fix the metal nanoparticles to the surface of fiber 11.

[0048] The conductive layer 30 has a bilayer structure, consisting of a nanoparticle layer 31 formed on the bonding layer 20 and a monolayer 33 stacked on the nanoparticle layer 31. The nanoparticle layer 31 is formed of metal nanoparticles on the bonding layer 20. The nanoparticle layer is fixed to the fabric support 10 by the bonding layer 20, as described above. The nanoparticle layer is formed on the inner and outer fibers 11 of the fabric support 10. The metal nanoparticles can be nanoparticles selected from, but not limited to, one or more metals selected from, but not limited to, Au, Ag, Al, Cu, and Pt.

[0049] The monolayer 33 is a layer formed by coating a monomolecular material on the nanoparticle layer 31. The monomolecular material contains one or more amine groups (NH2) and can be selected from, but is not necessarily limited to, tris(2)-aminoethyl)amine (TREN), propane-1,2,3-triamine, diethylenetriamine (DETA), tetra(aminomethyl)methane, methane tetraamine, and mixtures thereof. The monomolecular material is not particularly limited as long as it contains one or more amine groups. The monomolecular material, together with the polymeric material, immobilizes the metal nanoparticles and imparts electrical conductivity to the nanoparticle layer 31. A thin film composed of metal particles surrounded by long organic ligands exhibits insulating properties. In contrast, the polymeric material containing amine groups (for the binding layer 20) and the monomolecular material containing amine groups (for the monolayer 33) replace the insulating organic ligands to improve the binding strength between the metal nanoparticles and impart electrical conductivity to the nanoparticle layer 31.

[0050] The conductive layer 30 has a small electrical conductivity for electroplating, such that the catalyst layer 40 is formed by electroplating. The conductive layer 30 can have a sheet resistance in the range of 10 0 Ω / sq to 10 4 Ω / sq. Within this range, electroplating can be effectively performed. However, the sheet resistance of the conductive layer 30 is not necessarily limited to the range defined above and can be determined depending on the type of metal nanoparticles and monomolecular material, as well as the structure of the conductive layer 30, which will be described below.

[0051] The catalyst layer 40 is a layer formed by electroplating a catalytic metal on the conductive layer 30. The catalytic metal is a metal having catalytic activity for water splitting. For example, the catalytic metal can be selected from, but is not necessarily limited to, Ni, Co, Fe, Mo, Au, Ag, Cu, Cr, Ti, and alloys thereof. That is, the catalyst layer 40 can be formed of any metal and alloys thereof. The alloys can be, for example, NiCo and NiFe. Any catalytic metal that can be coated on the conductive layer 30 by electroplating and has catalytic activity for water splitting can be used without limitation. Electroplating enables the catalytic metal to be uniformly coated on the outer surface of the fiber 11 of the fabric support 10 at a high density. Since the conductive layer 30 is formed on the outer surface of the fiber 11 while maintaining the porosity of the fabric support 10, the catalyst layer 40 can be uniformly formed on the inner and outer fibers 11 of the fabric support 10, and thus its surface area increases. As a result, the fabric-based porous water splitting catalyst of the present application has high electrical conductivity at a level comparable to that of metals, and provides a large surface area through which an electrolyte can easily permeate and hydrogen and oxygen generated by the splitting of water can easily escape. Electroplating is performed in a simple manner in a short time, thereby reducing the time taken to prepare the catalyst, and enables the catalyst to be prepared at a low cost in an effectively controlled manner.

[0052] Figure 3 is a cross-sectional view of a fabric-based porous water-splitting catalyst according to the second embodiment of the present application, taken along Figure 2 line A-A' of FIG. 4B.

[0053] Referring to Figure 3 , the fabric-based porous water-splitting catalyst according to the second embodiment of the present application has a structure in which two or more conductive layers 30 are stacked together, i.e., a second conductive layer 30b is stacked on a first conductive layer 30a or another conductive layer 30 can be optionally stacked thereon. The nanoparticle layer 31 and the monolayer 33 of the different conductive layers 30 can be constructed using the same or different materials. For example, Au nanoparticles can be used for the nanoparticle layer 31a of the first conductive layer 30a, DETA can be used as the monomolecular material for the monolayer 33a of the first conductive layer, Ag nanoparticles can be used for the nanoparticle layer 31b of the second conductive layer 30b, and TREN can be used as the monomolecular material for the monolayer 33b of the second conductive layer. In this case, the conductive layer 30 has an (Au / DETA) / (Ag / TREN) bilayer structure.

[0054] Figure 4 is a cross-sectional view of a fabric-based porous water-splitting catalyst according to the third embodiment of the present application, and corresponds to a cross-sectional view taken along Figure 2 line A-A' of FIG. 5B.

[0055] As shown in Figure 4 , the fabric-based porous water-splitting catalyst can include a catalyst layer 40 including a metal layer 41 and a hydroxide layer 43.

[0056] The metal layer 41 is a layer containing a catalytic metal and is formed by electroplating, as described above. For example, the metal layer 41 can be a layer of electroplated Ni.

[0057] The hydroxide layer 43 is a layer containing a hydroxide of the catalytic metal. The metal layer 41 and the hydroxide layer function as catalytically active materials. The hydroxide layer 43 can be formed by immersing the fabric support 10 on which the metal layer 41 is formed into an alkaline solution. For example, a layer of Ni(OH)2as the hydroxide layer 43 can be formed on the surface of the Ni layer as the metal layer 41 by immersing the Ni metal layer 41 into a KOH solution. At this time, the Ni(OH)2may split the HO-O bond, and the Ni is adsorbed with the split intermediate H ad . The Ni serves as a primary material for recombining the adsorbed H ad into hydrogen. Thus, the metal layer 41 and the hydroxide layer 43 as catalytically active materials can form a single catalyst electrode without the use of an additional binder.

[0058] Figure 5 and Figure 6 is a cross-sectional view of a fabric-based porous water-splitting catalyst according to a fourth embodiment of the present application (see the cross-sectional view taken along the line A-A' of Figure 2 .

[0059] In the embodiments shown in Figure 5 and Figure 6 , two or more catalyst layers 40 are stacked together. That is, the catalyst layer can be a first catalyst layer 40a and a second catalyst layer 40b formed on the first catalyst layer. Each of the catalyst layers 40 can include a metal layer 41 and optionally further include a hydroxide layer 43. The metal layer 41 and the hydroxide layer 43 are the same as those described above. For example, only the metal layer 41 can be provided as the first catalyst layer 40, and the combination of the metal layer 41 and the hydroxide layer 43 can be provided as the second catalyst layer 40 to form a (metal layer) / (metal layer / hydroxide layer) structure, as shown in Figure 6 . Alternatively, two catalyst layers 40 can be stacked together to form a (metal layer / hydroxide layer) / (metal layer / hydroxide layer), (metal layer / hydroxide layer) / (metal layer), or (metal layer) / (metal layer) structure. Alternatively, three or more catalyst layers 40 can be stacked together to form a (metal layer) / (metal layer) / (metal layer / hydroxide layer) or (metal layer) / (metal layer / hydroxide layer) / (metal layer) structure. The constituent metal layers 41 of the catalyst layers 40 do not necessarily have to be formed of the same catalytic metal. Different catalytic metals can be used for the metal layers of the catalyst layers. In the case where different catalytic metals are used in the catalyst layers 40, the catalytic metal for the metal layer 41 of one of the catalyst layers 40 can be different from the catalytic metal for the hydroxide layer 43 (i.e., the catalytic metal prior to the formation of the hydroxide).

[0060] Inventive Embodiments

[0061] A description will be given of a method for preparing a fabric-based porous water-splitting catalyst according to the present application. The fabric-based porous water-splitting catalyst is the same as the catalyst described above, and its detailed description is omitted or only briefly introduced to avoid repetition.

[0062] Figure 7 and Figure 8 are a flowchart and a diagram, respectively, showing a method for preparing a fabric-based porous water-splitting catalyst according to one embodiment of the present application.

[0063] As Figure 7 and Figure 8As shown in the middle, the method includes: (a) preparing a first dispersion of a polymer material, and immersing a porous fabric support made by interlacing a plurality of fibers in the first dispersion to form a binding layer on the surface of the fibers (S100); (b) preparing a second dispersion of metal nanoparticles, and immersing the fabric support on which the binding layer is formed in the second dispersion to form a nanoparticle layer (S200); (c) preparing a third dispersion of an amine group-containing monomolecular material, and immersing the fabric support on which the nanoparticle layer is formed in the third dispersion to form a monomolecular layer (S300); and (d) electroplating a catalytic metal to form a catalyst layer on the monomolecular layer (S400).

[0064] Briefly, the method includes: forming a binding layer (S100); forming a nanoparticle layer (S200); forming a monomolecular layer (S300); and forming a catalyst layer (S400).

[0065] In S100, the binding layer is formed on the surface of the fibers constituting the fabric support. Specifically, a first dispersion of a polymer material is prepared and the fabric support is immersed in the first dispersion to form the binding layer. The fabric support is a porous substrate made by interlacing a plurality of fibers. The first dispersion penetrates into the fabric support through the pores of the fabric support, and the polymer material is adsorbed to the surface of the internal fibers as well as the surface of the external fibers. The fibers can be selected from, but are not necessarily limited to, cellulose fibers, polyester fibers, nylon fibers, acrylic fibers, and mixtures thereof. The polymer material is a polymer containing an amine group and can be selected from, but is not necessarily limited to, polyethyleneimine (PEI), poly(allylamine hydrochloride) (PAH), and mixtures thereof. The first dispersion can be prepared using any solvent capable of dispersing the polymer material to form the binding layer on the surface of the fibers. The solvent for the first dispersion is not particularly limited and can be, for example, ethanol.

[0066] In S200, metal nanoparticles are coated on the binding layer to form a nanoparticle layer. Specifically, a second dispersion of metal nanoparticles is prepared and the fabric support on which the binding layer is formed is immersed in the second dispersion to form the nanoparticle layer. Since the pores of the fabric support are not closed by the binding layer, the second dispersion penetrates into the fabric support through the pores of the fabric support and is coated on the binding layer adsorbed to the surface of the fibers. The metal nanoparticles can be nanoparticles of one or more metals selected from, but not necessarily limited to, Au, Ag, Al, Cu, and Pt. The second dispersion can be prepared by dispersing the metal nanoparticles in a suitable solvent, including but not necessarily limited to toluene.

[0067] In S300, a thin monolayer is formed using an amine group-containing monomolecular material. Specifically, the amine group-containing monomolecular material is dispersed in a suitable solvent such as ethanol to prepare a third dispersion, and the fabric support on which the nanoparticle layer is formed is immersed in the third dispersion to form a monolayer. The third dispersion penetrates into the fabric support through the pores of the fabric support, and the monomolecular material is coated on the nanoparticle layer formed on the surfaces of the external and internal fibers to form a monolayer. The monomolecular material can be selected from, but is not necessarily limited to, tris(2-aminoethyl)amine (TREN), propane-1,2,3-triamine, diethylenetriamine (DETA), tetra(aminomethyl)methane, methane tetraamine, and mixtures thereof. The nanoparticle layer and the monolayer stacked on the nanoparticle layer form a conductive layer.

[0068] The conductive layer has as low conductivity as possible so that a catalyst layer is formed by electroplating. The sheet resistance of the conductive layer is preferably in the range of 10 0 Ω / sq to 10 4 Ω / sq. This range can be achieved by appropriately selecting the type of metal nanoparticles or forming the conductive layer in a multilayer structure. Referring to Figure 8 , two or more conductive layers can be formed by sequentially repeating S200 and S300 several times ("layer-by-layer assembly"). In this case, the same material can be used for the constituent metal nanoparticle layer and monolayer of different conductive layers. Alternatively, at least one of these materials can be replaced with a different material.

[0069] In S400, a catalytic metal is electroplated on the conductive layer. The catalytic metal can be selected from, but is not particularly limited to, Ni, Co, Fe, Mo, Au, Ag, Cu, Cr, Ti, and alloys thereof. The layer formed by electroplating the catalytic metal is defined as a metal layer. The catalyst layer can also include a hydroxide layer. The hydroxide layer can be formed by immersing the metal layer in an alkaline solution. The alkaline solution can be, for example, a KOH solution. The alkaline solution is not particularly limited as long as it can chemically react with the metal layer to form a hydroxide layer on the surface of the metal layer.

[0070] The catalyst layer can be provided in plural, and the plural catalyst layers can be stacked together. Each of the catalyst layers can optionally include a hydroxide layer in addition to the metal layer. To this end, electroplating and immersion in an alkaline solution are selectively performed.

[0071] The present application will be explained more specifically with reference to Examples and Evaluation Examples.

[0072] Example: Preparation of Fabric-Based Porous Water Splitting Catalyst

[0073] A first dispersion was prepared by dispersing PEI having amine groups in ethanol to a concentration of 2 mg / mL. Thereafter, a porous fabric support made of cellulose (“cellulose substrate”) was immersed in the first dispersion for 3 hours, washed twice with ethanol, and dried with a desiccator. Au nanoparticles were hydrophobically stabilized with tetraoctyl ammonium bromide (TOABr) and dispersed in toluene to prepare a second dispersion. Then, the fabric support was immersed in the second dispersion for 1 hour, washed twice with toluene, dried with a desiccator, and immersed in a 2 mg / mL solution of diethylenetriamine (DETA) in ethanol (third dispersion) for 30 minutes. DETA is a monomolecular compound having amine groups. Again, the fabric support was washed twice with ethanol and dried. The sequential immersions in the second and third dispersions resulted in the formation of a (TOABr-Au NP / DETA) structure in which Au nanoparticles and the monomolecular compound DETA are stacked by layer-by-layer assembly. Au nanoparticles and DETA as a monomolecular compound are alternately stacked on the structure to form a conductive layer (cotton / PEI / (TOABr-Au / DETA) n ) until a thin layer resistance of 10 0 Ω / sq to 10 4 Ω / sq is achieved.

[0074] Then, electroplating was performed in a Watt’s bath with a Ni plating solution at 1.3 A for 30 minutes. The type and composition of the plating solution vary depending on the desired plating metal. Specifically, the fabric support as a cathode and the desired plating metal as an anode were immersed in an electrolyte solution and connected to a power source. Electricity was applied to the two electrodes to form a catalyst layer on the conductive layer stack. The plated fabric support was washed twice with deionized water (DI). Thereafter, NiFe plating was performed once.

[0075] The plated fabric support was placed in a vacuum oven at 150 °C, dried for 3 hours, immersed in a 0.1 M KOH solution for 1 hour, washed twice with DI, and dried.

[0076] The resulting water-splitting catalyst had the following structures: cotton / PEI / (TOABr-Au NP / DETA)4 / Ni, cotton / PEI / (TOABr-Au NP / DETA)4 / NiCo, cotton / PEI / (TOABr-Au NP / DETA)4 / Ni / NiFe, and cotton / PEI / (TOABr-Au NP / DETA)4 / Ni / Ni(OH)2.

[0077] Example 1: Analysis of the relationship between the number of conductive layers and the thin layer resistance value

[0078] As the number (n) of the stacked conductive layers (TOABr-Au / DETA) in the sample increases, the thin layer resistance value of the cotton / PEI / (TOABr-Au / DETA)4 / Ni sample prepared in the measurement example n The thin layer resistance value of the sample. The results are shown in Figure 9 .

[0079] Referring to Figure 9 , the number of the stacked conductive layers has a reverse proportional relationship with the thin layer resistance. In the example, the number of the conductive layers formed by plating is 4, each of the conductive layers has a double layer structure, and the thin layer resistance before plating is 10 0 Ω / sq to 10 4 Ω / sq.

[0080] Evaluation Example 2: Analysis of the structure of the fabric-based porous water-splitting catalyst

[0081] Figures 10a to 10c are scanning electron microscope (SEM) images of the fabric-based porous water-splitting catalyst prepared in the example. Specifically, Figure 10a , Figure 10b and Figure 10c show plan and cross-sectional SEM images of the cotton / PEI / (TOABr-Au NP / DETA)4 / Ni, cotton / PEI / (TOABr-Au NP / DETA)4 / Ni / NiFe, and cotton / PEI / (TOABr-Au NP / DETA)4 / NiCo samples, respectively.

[0082] Figure 10a , Figure 10b , Figure 10c Analysis of the cross-sectional SEM data shown in

[0083] Evaluation Example 3: Evaluation of the activity for the hydrogen evolution reaction

[0084] Figures 11a to 11c shows the results of the evaluation of the activity of the fabric-based porous water-splitting catalyst prepared in the example for the hydrogen evolution reaction.

[0085] The electrochemical catalytic properties of the cotton / PEI / (TOABr-Au NP / DETA)4 and cotton / PEI / (TOABr-Au NP / DETA)4 / Ni / Ni(OH)2 samples prepared in the measurement examples were investigated. First, each sample was cut into 0.5cm × 1cm pieces. Except for the measurement portion (0.5cm × 0.5cm) and the portion held by pliers, the pieces were finished with epoxy resin and connected to a reversible hydrogen electrode (RHE) as the reference electrode and a Pt mesh as the counter electrode in a three-electrode system in 1M KOH electrolyte. The current density (j, mA cm⁻¹) of the catalyst was measured under varying potentials (V relative to the RHE). -2 The results are shown in Figure 11a and Figure 11b In the middle. The overpotential (V) of the sample without electroplated Ni (EL: electrodeless deposition) and the overpotential of the sample with electroplated Ni (EP: electroplating) (see Figure 11a The results are shown in the comparison. Figure 11c middle.

[0086] The activities of commercial Ni foam, electroless Ni-coated samples (EL Ni-cotton), and Ni-plated samples (EP Ni-cotton) for the hydrogen evolution reaction (HER) in 1 MKOH electrolyte were compared (see [link to relevant documentation]). Figure 11a As a result, the Ni-plated catalyst exhibited the highest performance. TOABr-Au nanoparticles did not contribute to the activity of the Ni-plated catalyst for the hydrogen evolution reaction (see [link to relevant documentation]). Figure 11b ).

[0087] At -10mA cm -2 The overpotentials of the unplated sample (EL Ni-cotton) and the electroplated sample (EP Ni-cotton) with the same cotton thickness were measured to be 87 mV and 12 mV, respectively, indicating that the performance of the electroplated Ni catalyst is superior to that of the unplated Ni catalyst (see [reference]). Figure 11c ).

[0088] Evaluation Example 4: Evaluation of the activity of the oxygen evolution reaction

[0089] Figure 12 The results of the evaluation of the activity of the fabric-based porous water splitting catalyst prepared in the examples for the oxygen evolution reaction are shown.

[0090] The activity of the commercial Ni foam, the galvanic Ni sample (EP Ni-cotton) and the galvanic NiFe sample (EP NiFe LDH / Ni-cotton) for the oxygen evolution reaction was evaluated. To this end, each of the samples was connected to a reversible hydrogen electrode (RHE) as reference electrode and a Pt mesh as counter electrode in a three-electrode system in 1 M KOH electrolyte and the current density (j, mA cm -2 ) of the catalyst was measured as a function of the potential (V vs. RHE), see Figure 12 . As a result, the additional NiFe plating on the plated Ni layer leads to an improvement of the catalytic performance.

[0091] Example 5: Evaluation of the activity for the hydrogen evolution reaction and the oxygen evolution reaction

[0092] Figure 13a and Figure 13b The results of the evaluation of the activity of the fabric-based porous water splitting catalysts prepared in the examples for the hydrogen evolution reaction and the oxygen evolution reaction are shown.

[0093] The activity of the water splitting catalysts for water splitting was measured. To this end, a galvanic Ni sample was connected to the cathode (-) and a galvanic Ni sample was connected to the anode (+) in 1 M KOH electrolyte. The cell voltage was measured at 10 mA cm -2 , 50 mA cm -2 and 100 mA cm -2 as 1.39 V, 1.57 V and 1.62 V, respectively (see Figure 13a ).

[0094] Referring to Figure 13b , when a constant current density of 10 mA cm -2 was applied to both electrodes, almost no change in the cell potential was observed for 100 hours. The current density (j) - voltage curves before and after the stability test matched well, indicating a high catalyst stability.

[0095] While the application has been described herein with respect to the above specific embodiments, the embodiments are not intended to limit the application, but on the contrary, are meant to illustrate the application for the purposes of exemplification. It will be apparent to those skilled in the art that modifications and improvements can be made without departing from the spirit and scope of the application.

[0096] Simple modifications and variations of the application are within the scope of the application, and the particular scope of the application will be set forth in the appended claims.

[0097] [Legend of the figures]

[0098] 10: fabric support 11: fiber

[0099] 20: bonding layer 30: conductive layer

[0100] 31: nanoparticle layer 33: monolayer

[0101] 40: catalyst layer 41: metal layer

[0102] 43: hydroxide layer

[0103] Industrial applicability

[0104] In the water-splitting catalyst of the present application, metal is uniformly coated on all fiber strands constituting the porous insulating fabric structure by electroplating. This uniform coating ensures excellent charge transport properties of the water-splitting catalyst and the conductivity of the water-splitting catalyst equivalent to that of the metal. Thus, the present application is considered to be industrially applicable.

Claims

1. A porous water splitting catalyst based on fabric, comprising: A porous fabric support made by interlacing multiple fibers; a bonding layer formed on the surface of the fibers; a conductive layer comprising a nanoparticle layer containing metal nanoparticles and formed on the bonding layer and a monomolecular layer containing an amine-containing (NH2) monomolecular material and formed on the nanoparticle layer. and a catalyst layer, the catalyst layer comprising a catalytic metal and formed by electroplating the catalytic metal onto the conductive layer. The catalyst layer Includes: a metal layer, wherein the metal layer contains the catalytic metal; and the hydroxide layer formed on the surface of the metal layer, The hydroxide layer is formed by immersing the metal layer in an alkaline solution. The metal layer mentioned above is a Ni layer. The hydroxide layer is a Ni(OH)2 layer. The sheet resistance of the conductive layer is 10. 0 Ω / sq up to 10 4 Ω / sq, so that the Ni layer is formed by electroplating. The conductive layers are configured in plurality of units, and the plurality of conductive layers are stacked together to achieve a density of 10. 0 Ω / sq up to 10 4 Thin-film resistance in Ω / sq.

2. The fabric-based porous water splitting catalyst according to claim 1, wherein the fiber is selected from cellulose fiber, polyester fiber, nylon fiber, acrylic fiber, and mixtures thereof.

3. The fabric-based porous water splitting catalyst according to claim 1, wherein the binding layer comprises an amine-containing (NH2) polymer material.

4. The fabric-based porous water splitting catalyst according to claim 3, wherein the polymer material is selected from polyethyleneimine (PEI), poly(allylamine hydrochloride) (PAH), and mixtures thereof.

5. The fabric-based porous water splitting catalyst according to claim 1, wherein the metal nanoparticles are nanoparticles of one or more metals selected from Au, Ag, Al, Cu and Pt.

6. The fabric-based porous water splitting catalyst according to claim 1, wherein the single-molecule material is selected from tris(2-aminoethyl)amine (TREN), propane-1,2,3-triamine, diethylenetriamine (DETA), tetra(aminomethyl)methane, methanetetraamine, and mixtures thereof.

7. A method for preparing a fabric-based porous water splitting catalyst, comprising: (a) A first dispersion of a polymer material is prepared, and a porous fabric support made by interlacing multiple fibers is immersed in the first dispersion to form a bonding layer on the surface of the fibers; (b) A second dispersion of metal nanoparticles is prepared, and the fabric support on which the bonding layer is formed is immersed in the second dispersion to form a nanoparticle layer; (c) A third dispersion of an amino-containing monomolecular material is prepared, and the fabric support on which the nanoparticle layer is formed is immersed in the third dispersion to form a monomolecular layer; (d) Electroplating a catalytic metal to form a catalyst layer on the monolayer, Step (d) includes: electroplating a catalytic metal to form a metal layer; And immersing the metal layer in an alkaline solution to form a hydroxide layer on the surface of the metal layer, The metal layer mentioned above is a Ni layer. The hydroxide layer is a Ni(OH)2 layer. This includes the nanoparticle layer and the conductive layer of the monolayer stacked on the nanoparticle layer, with a sheet resistance of 10. 0 Ω / sq up to 10 4 Ω / sq, so that the Ni layer is formed by electroplating. Steps (b) and (c) are sequentially repeated at least twice before step (d) to form at least two conductive layers stacked together, such that 10 0 Ω / sq up to 10 4 Thin-film resistance in Ω / sq.

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