A fluid-routing element for an electrochemical reactor and methods of producing the same

Abstract

There is provided herein a fluid-routing element for use in an electrochemical reactor, the fluid-routing element includes a flow-field channel(s), wherein the flow-field channel(s) includes a gas-repelling layer, and wherein a forefront of the element facing a reaction zone of the electrochemical reactor is essentially devoid of the gas-repelling layer.

Description

[0001] A FLUID-ROUTING ELEMENT FOR AN ELECTROCHEMICAL REACTOR AND METHODS OF PRODUCING THE SAME

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to the field of electrolysis. More specifically, the disclosure relates to a fluid-routing element for use in an electrochemical reactor and methods of producing the same.

[0004] BACKGROUND

[0005] Electrolysis is a method of producing hydrogen while utilizing renewable resources and avoiding carbon emissions. It involves splitting water into hydrogen and oxygen using electricity in an electrochemical reactor called an electrolyzer. The cell may consist of a solid electrolyte ion-conducting membrane positioned between an anode and a cathode. The membrane allows the transition of liquid and gaseous products and is enclosed by plates that function as current collectors. Gas-producing systems, such as proton exchange membrane PEM water electrolyzers (PEMWE), are known for their high efficiency, compact design, and ability to produce high-purity hydrogen. They are widely used in applications such as hydrogen production for fuel cells, industrial processes, and renewable energy storage. Notably, the water supply and gas removal rates depend heavily on the fluid distribution in the current collectors.

[0006] One way to ensure the effective flow of fluids is by using engraved flow field electrodes in the current collector. However, this alone is not sufficient to maintain optimal cell efficiency. When gas bubbles of hydrogen and oxygen are formed during the electrolysis process, they tend to stick to the current collector's surface. This reduces the active area of the current collector, creating non-uniform pressure gradients throughout the flow channels, thus leading to lower cell efficiency and achievable current densities. Therefore, it is essential to effectively remove gas bubbles and maintain a uniform distribution of liquid over the electrode surface for optimal performance.

[0007] Furthermore, current collectors experience hydrogen embrittlement and surface damage with time of operation, particularly in large-scale production of gas. Accordingly, there is a need in the art for a current collector that can operate effectively by promoting the desired flow pattern while reducing the formation of saddled gas bubbles. Moreover, the current collector should have improved resistance against surface damage.

[0008] SUMMARY

[0009] The disclosure is directed, in embodiments thereof, to a fluid-routing element for use in an electrochemical reactor, particularly in an electrolyzer generating gaseous products. In some embodiments, the electrochemical reactor may be utilized, for example, in the production of hydrogen and / or oxygen gas products. Further provided herein, in some embodiments thereof, are methods of producing the fluid-routing element. In some embodiments, further provided herein are uses of the fluid-routing element as a current collector that includes a flow field.

[0010] According to some embodiments, the fluid-routing element is configured to effectively route the produced gas through flow-field channels of the element away from the current collector. According to some embodiments, the flow-field channels are surface-modified to route the gaseous product away from the current collector effectively.

[0011] Advantageously, and in accordance with some embodiments, the flow-field channels are coated with a gas-repelling, i.e., aerophobic layer. Advantageously, and in accordance with some other embodiments, the flow-field channels have a rough gas-repelling layer.

[0012] According to some embodiments, the effective gas routing by the element, advantageously, decreases the energy demand of a hydrogen production process and enhances the faradaic efficiency of an electrochemical reaction. According to some embodiments, the effective gas routing by the element, advantageously, enhances the efficiency of the gas production in the electrochemical reactor, in general, and the gas production in an electrolyzer, in particular. In some embodiments, such an electrochemical reactor may be, for example, a proton exchange membrane water electrolyzer (PEMWE), an alkaline membrane or diaphragm water electrolyzer, or a decoupled water electrolyzer.

[0013] According to some further embodiments, the fluid-routing element is fabricated to protect the surface thereof against corrosion and hydrogen embrittlement and, thereby, prevent surface damage and / or prevent an increase in ohmic resistance of a current collector-electrode interface. According to some embodiments, the advantageous fluid-routing element disclosed herein is configured to prolong the life span of an electrode in general, and a current collector in particular. According to some embodiments, the advantageous fluid-routing element is capable of enhancing the overall durability and efficiency of the electrochemical reactor.

[0014] According to some embodiments, further provided herein are methods for producing the fluid-routing element by applying a gas-repelling layer on the surface of the flow-field channels.

[0015] There is provided herein, in accordance with some embodiments, a fluid-routing element for use in an electrochemical reactor, the fluid-routing element includes flow-field channel(s), wherein the flow-field channel(s) includes a gas-repelling layer, and wherein a forefront of the element facing a reaction zone of the electrochemical reactor is essentially devoid of the gas-repelling layer.

[0016] According to some embodiments, the gas-repelling layer includes hydrophilized graphene, hydrophilized graphite, hydrophilic polymer, hydrophilized polymer, polyelectrolyte, metal oxide, ceramic material, hydrogel, or any combination thereof.

[0017] According to some embodiments, the hydrophilized polymer includes polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), epoxy, polypropylene (PP), polyethylene, polystyrene (PS), polyvinylchloride (PVC), polydimethylsiloxane (PDMS), polyesters, polyurethanes, polycaprolactone, polypropylene oxide (PPO), block copolymers thereof, cross-linked version thereof, chemical modification thereof, or any combination thereof.

[0018] According to some embodiments, the hydrophilic polymer includes polyacrylate (PA), polyacrylic acid (PAA), polyvinyl alcohol (PVA), polyacrylamide (PAM), poly(N-(2- hydroxypropyl)methacrylamide) (PHPMA), poly(N,N-dimethylacrylamide) (PDMA), polyethylene glycol (PEG), polyethylenimine (PEI), polylysine (PLL), poly(lysine isophthal ami de) (PLP), poly(2-hydroxyethyl methacrylate) (PHEMA), polyvinylpyrrolidone (PVP), polysaccharides, block copolymers thereof, cross-linked version thereof, derivatives thereof, or any combination thereof. According to some embodiments, the gas-repelling layer includes, or is, a roughened surface layer.

[0019] According to some embodiments, a surface roughness of the roughened surface layer at the flow-field channel(s) is at least about 5-fold higher compared to a surface roughness of the forefront of the element.

[0020] According to some embodiments, the flow-field channels are engraved to form an engraved flow field.

[0021] According to some embodiments, the engraved flow field has a geometry including: serpentine, multi-channel serpentine, parallel channels, cascade channels, pin-type, or any combination thereof.

[0022] According to some embodiments, the flow-field is in a form selected from a group consisting of woven wire cloth, criss-cross, expanded mesh, monoliths of porous sintered powder, and any combination thereof.

[0023] According to some embodiments, the channels have dimensions of between 0.5-3 mm in width and between 0.5-3 mm in depth.

[0024] According to some embodiments, a geometric ratio between the surface area of the forefront and the surface area of the channels is in a range of between 1 : 1-2:3, respectively.

[0025] According to some embodiments, a body of the fluid-routing element is made of: titanium, gold, iron, nickel, copper, aluminum, graphite, stainless steel, alloys thereof, a composite of organic-inorganic material thereof, or any combination thereof.

[0026] According to some embodiments, the electrochemical reactor is an electrolytic cell.

[0027] According to some embodiments, the electrolytic cell is selected from: a proton exchange membrane water electrolyzer, an alkaline membrane water electrolyzer, and a decoupled water electrolyzer.

[0028] According to some embodiments, the reaction zone includes a separator, a gas diffusion layer (GDL), a porous transport layer (PTL), a catalyst layer, or any combination thereof. According to some embodiments, the separator is selected from: a proton exchange membrane, an anion exchange membrane, an ion-solvating membrane, a bi-polar membrane, and a diaphragm.

[0029] According to some embodiments, the fluid-routing element is configured to conduct an electrical current to, and from, the reaction zone, and / or to remove a gaseous product from the reaction zone.

[0030] According to some embodiments, the gaseous product is hydrogen and / or oxygen.

[0031] According to some embodiments, the fluid-routing element is associated with a hydrogen-evolving cathode.

[0032] According to some embodiments, the fluid-routing element is associated with an oxygen-evolving anode.

[0033] According to some embodiments, the fluid-routing element is for use as a current collector of a mono-polar or a bipolar electrode.

[0034] According to some embodiments, the flow-field channel(s) are engraved and coated with the hydrophilized polymer, and wherein the forefront of the element does not include the hydrophilized polymer.

[0035] There is provided herein, in accordance with some embodiments, a method for producing a fluid-routing element disclosed herein, the method includes: obtaining a current collector including flow-field channels; applying a gas-repelling layer on the current collector; and removing the applied layer from the forefront of the current collector, to obtain the fluid-routing element, such that the flow-field channels include the gas-repelling layer, and wherein the forefront of the element is essentially devoid of the gas-repelling layer.

[0036] According to some embodiments, the method further includes forming a patterned channel morphology on, or in, the current collector. According to some embodiments, the formation of the patterned channel morphology includes electro-deposition, electroless-deposition, (photo)lithography, sputtering, chemical vapor deposition, printing, etching, engraving, curving, or any combination thereof.

[0037] According to some embodiments, the current collector is surface-pre-treated prior to applying the gas-repelling layer.

[0038] According to some embodiments, applying the gas-repelling layer is facilitated by using a technique selected from: electro-deposition, thermal deposition, chemical vapor deposition, physical vapor deposition, sputtering, spraying, layer-by-layer deposition, brushing, spin coating, pre-made film layer coating, printing, dip coating, spray coating, and any combination thereof.

[0039] According to some embodiments, applying the gas-repelling layer further includes hydrophilizing the applied material and / or the surface thereof.

[0040] According to some embodiments, applying the gas-repelling layer includes roughening the surface of the element by a chemical and / or physical method.

[0041] According to some embodiments, the chemical and / or physical roughening method includes etching, sandblasting, and / or anodizing.

[0042] According to some embodiments, the removal of the gas-repelling layer from the forefront of the element includes grinding, etching, sandblasting, sanding, buffing, leaching, oxidation, scraping, polishing, or any combination thereof.

[0043] Certain embodiments of the present disclosure may include some, all, or none of the above advantages. One or more technical advantages may be readily apparent to those skilled in the art from the figures, descriptions and claims included herein. Moreover, while specific advantages have been enumerated above, various embodiments may include all, some or none of the enumerated advantages.

[0044] In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the figures and by study of the following detailed descriptions. BRIEF DESCRIPTION OF THE FIGURES

[0045] Some embodiments of the disclosure are described herein with reference to the accompanying figures. The description, together with the figures, makes apparent to a person having ordinary skill in the art how some embodiments may be practiced. The figures are for the purpose of illustrative description and no attempt is made to show structural details of an embodiment in more detail than is necessary for a fundamental understanding of the disclosure. For the sake of clarity, some objects depicted in the figures are not to scale.

[0046] In the figures:

[0047] FIGURE 1 - shows an exemplary schematic illustration of a fluid-routing element including a gas-repelling layer, according to some embodiments; and

[0048] FIGURE 2 - shows an exemplary flowchart of steps of a method for producing a partially coated fluid-routing element, according to some embodiments.

[0049] DETAILED DESCRIPTION

[0050] In the following description, various aspects of the disclosure will be described. For the purpose of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the different aspects of the disclosure. However, it will also be apparent to one skilled in the art that the disclosure may be practiced without specific details being presented herein. Furthermore, well-known features may be omitted or simplified in order not to obscure the disclosure.

[0051] Prior to setting forth the present subject matter in detail, it may be helpful to provide definitions of certain terms to be used herein. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this subject matter pertains. The following definitions are provided for clarity.

[0052] The term "a" or "an" as used herein includes the singular and the plural, unless specifically stated otherwise. Therefore, the terms "a," "an", or "at least one". As used herein, the verb "comprise" as is used in this description and in the claims and its conjugations are used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded.

[0053] As used herein, the term "about" when used in connection with a numerical value includes ±10% from the indicated value. In addition, all ranges directed to the same component or property herein are inclusive of the endpoints, are independently combinable, and include all intermediate points and ranges. It is understood that where a parameter range is provided, all integers within that range, and tenths thereof, are also provided by the invention.

[0054] Rates of water supply and gas removal in an electrochemical reactor depend mainly on the liquid and gas distribution in the current collector, the crossover of water through a membrane (or diaphragm), and the current density. While the flow-field of a current collector may aid the flow of the liquid, gas bubbles formed and settled during electrolysis reduce its active area, increase resistance, and create non-uniform pressure gradients and voltage distribution over the electrode surface. Therefore, it is crucial to effectively remove the gas bubbles and uniformly distribute the liquid for optimal cell performance.

[0055] The disclosure herein relates to a fluid-routing element configured to effectively route the produced gas through flow-field channels of the element away from the current collector. In order to effectively do so, the flow-field channels include or are coated with a gas-repelling layer that can more effectively distribute the gas away from the current collector. The reduction in gas settlement further reduces the resistance and, in turn, lowers the overall energy consumption of the electrochemical reactor. In addition, the effective routing of the gas by the element enhances the efficiency of the gas production in the electrochemical reactor, in general, and the gas production in an electrolyzer, in particular.

[0056] There is provided herein, in accordance with some embodiments, a fluid-routing element for use in an electrochemical reactor, the fluid-routing element includes flow-field channel(s), wherein the flow-field channel(s) includes a gas-repelling material layer, and wherein a forefront of the element facing a reaction zone of the electrochemical reactor, is essentially devoid of the gas-repelling material.

[0057] There is provided herein, in accordance with some embodiments, a fluid-routing element for use in an electrochemical reactor, the fluid-routing element includes a flow-field channel(s), wherein the flow-field channel(s) are at least partially coated with a gas-repelling material layer, wherein a forefront of the element facing a reaction zone of the electrochemical reactor is essentially devoid of the gas-repelling material.

[0058] According to some embodiments, the flow-field channels’ surface area includes the gas-repelling layer in at least about 25% portion of its surface, for example, about 25-35%, at least about 35-45%, at least about 45-55%, at least about 55-65%, at least about 65-75%, at least about 75-85%, or at least about 89-95% of the flow-field channels’ surface area. Each possibility is a separate embodiment.

[0059] According to some embodiments, the partial coating of the flow-field channels covers at least about 25% of the flow-field channels’ surface area, for example, about 25-35%, at least about 35-45%, at least about 45-55%, at least about 55-65%, at least about 65-75%, at least about 75-85%, or at least about 89-95% of the flow-field channels’ surface area. Each possibility is a separate embodiment.

[0060] As used herein, in accordance with some embodiments, the term “flow-field channels’ surface area” refers to the surface area at the bottom of the channels as well as to the surface area of the sides / walls of the channels.

[0061] According to some embodiments, the surface area of the bottom of the channels determines the current collection and distribution, as well as the distribution of reactant / product.

[0062] According to some embodiments, the surface area of the sides of the channels determines reactant / product distribution and fluid dynamics.

[0063] As used herein, in accordance with some embodiments, the term “channels” refers to the inner part of structured pathways that are designed to direct the flow of fluids (gases or liquids) through a specific area or system. The channels, according to some embodiments, ensure an efficient distribution of a reactant and / or product. Channels’ pathways may be included between / within the form of engraved / non-engraved flow fields that may be selected from, but are not limited to, woven (metal) wire (cloth), sintered, expanded mesh, monoliths of porous sintered powder, serpentine, multi-channel serpentine, parallel channels, cascade channels, or pin-type, according to some embodiments. Each possibility is a separate embodiment. The channels have width, height, and length, according to some embodiments. According to some embodiments, the channels have a width of between 0.5-3 mm, for example, between 0.5-1.0 mm, between 1.0-1.5 mm, between 1.5-2.0 mm, between 2.0-2.5, or between 2.5-3.0 mm. Each possibility is a separate embodiment.

[0064] According to some embodiments, the channels have a depth of between 0.5-3 mm, for example, between 0.5-1.0 mm, between 1.0-1.5 mm, between 1.5-2.0 mm, between 2.0-2.5, or between 2.5-3.0 mm. Each possibility is a separate embodiment.

[0065] According to some embodiments, a geometric ratio between the surface area of the flow-field channels and the surface area of the element’s forefront is in a range of between 1:1- 2: 1, respectively, for example, between 1 :1-1.8: 1, between 1 : 1-1.7: 1, between 1.1 : 1-1.6: 1, between 1.2: 1-1.6: 1, between 1.3: 1-1.6:1, or between 1.4: 1-1.6: 1, respectively. Each possibility is a separate embodiment.

[0066] According to some embodiments, the gas-repelling layer is divided between the bottom and the sides of the channels in a ratio of about 80 / 20, about 70 / 30, about 60 / 40, about 50 / 50, about 40 / 60, about 30 / 70, or about 20 / 80, respectively. Each possibility is a separate embodiment.

[0067] As used herein, in accordance with some embodiments, the term “gas-repelling material”, which can interchangeably be termed as “gas-phobic material” or “(super)aerophobic material”, refers to a material that resists the adhesion, absorption, adsorption, or penetration of gases.

[0068] In some embodiments, as used herein, the term “gas-repelling material layer” and the term “gas-repelling layer” can be used interchangeably. The terms refer to: 1. a coating layer that is applied to the flow field (e.g., a coating layer made of hydrophilized polymer), and / or 2. a surface of a flow field that is modified (e.g., roughened titanium).

[0069] According to some embodiments, the gas-repelling layer is configured to repel gas molecules from the surface. The gas-repelling layer is utilized to maintain a gas-minimum environment or to prevent a gas-induced degradation or contamination, such as hydrogen embrittlement, according to some embodiments. In some embodiments, the gas-repelling material is characterized by low surface energy. According to some embodiments, the gasrepelling material is hydrophilic or hydrophilized. According to some embodiments, examples for the gas-repelling material layer may include, but are not limited to, wet-etched / plasma- treated hydrophilized fluoropolymer (e.g., PTFE / Teflon), (oxygen) plasma-treated-PDMS, or graphene monolayer. Each possibility is a separate embodiment.

[0070] According to some embodiments, the forefront of the element is not part of the flowfield channels' surface area. According to some embodiments, the forefront of the element is essentially not coated with the gas-repelling layer. According to some embodiments, the forefront’s surface is in contact with an electrolyte and / or a (electrolytic) separator between the cathode and the anode.

[0071] In some embodiments, the separator is a conductive membrane. In some embodiments, the separator is a solid polymer electrolyte. In some embodiments, the separator is a proton exchange membrane (PEM).

[0072] As used herein, in accordance with some embodiments, the term “proton exchange membrane”, “PEM”, or a “polymer electrolyte membrane” refers to a semi-permeable membrane that facilitates the transport of protons (H+) from the anode to the cathode while acting as a barrier to electrons and gases. According to some embodiments, selective ion conduction is critical for the electrochemical reaction involved in water splitting and hydrogen production. The PEM may be made of, but is not limited to, according to some embodiments, perfluoro sulfonic acid polymer (e.g., Nafion, Aquivion, Flemion), sulfonated hydrocarbon polymers (e.g., poly ether ether ketone, polyphenylene sulfide), reinforced perfluoro sulfonic acid polymer composite, silica-perfluoro sulfonic acid polymer composite, or zirconia- perfluoro sulfonic acid polymer composite. Each possibility is a separate embodiment.

[0073] As used herein, in accordance with some embodiments, the term “essentially not coated / uncoated”, “does not include the gas repelling layer”, or “essentially devoid of the gasrepelling material” refers to the surface of the element’s forefront that essentially is not coated or that does not include the gas-repelling material. In some embodiments, the aforementioned terms refer to the surface of the element’s forefront that may be coated by, or include, a residual amount of the gas-repelling material. In some embodiments, the residual amount of the gasrepelling material on the element’s forefront covers a surface area that is less than about 10% of the forefront’s surface area, for example, less than about 8%, less than about 5%, less than about 3%, less than about 1%, or less than about 0.1% of the forefront’s surface area. Each possibility is a separate embodiment. A reference is now made to Fig. 1, which schematically exemplifies a partially coated fluid-routing element 100, according to some embodiments. In the example, the fluid-routing element includes the channels of the flow-field 101 coated with the gas-repelling material layer. The forefront 102 of the element is essentially uncoated with the gas-repelling material layer, according to some embodiments.

[0074] According to some embodiments, the gas-repelling material includes, but is not limited to, hydrophilized graphene, hydrophilized graphite, hydrophilic polymer, hydrophilized polymer, polyelectrolyte, metal oxides, ceramic material, hydrogel, or any combination thereof. Each possibility is a separate embodiment.

[0075] In some embodiments, the hydrophilized graphene gas-repelling material may be selected from, but is not limited to, graphene oxide, reduced graphene oxide, and any combination thereof. Each possibility is a separate embodiment.

[0076] As used herein, in accordance with some embodiments, the term “hydrophilized” refers to a material that has been chemically or physically modified to increase its hydrophilicity or affinity for water. As used herein, in accordance with some embodiments, the term “hydrophilized polymer” refers to a polymer that has been chemically or physically modified to increase its hydrophilicity, or affinity for water. This transformation involves introducing polar functional groups (such as hydroxyl, carboxyl, or amine groups) onto the material’ s / polymer's surface or structure, allowing the material / polymer to interact more effectively with water molecules. The modification can be obtained, for example, by chemical grafting or plasma treatment. Hydrophilized polymer repels gases, like hydrogen, more effectively because of their affinity for water leading to the formation of a hydration layer that acts as a barrier.

[0077] In some embodiments, the hydrophilized polymer gas-repelling material may include, but is not limited to, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), epoxy, polypropylene (PP), polyacrylate (PA), polyethylene, polystyrene (PS), polyvinylchloride (PVC), polydimethylsiloxane (PDMS), polyesters, polyurethanes, polycaprolactone, polylactic acid (PLA), polypropylene oxide (PPO), block copolymers thereof, cross-linked version thereof, derivatives thereof, or any combination thereof. Each possibility is a separate embodiment. According to some embodiments, the hydrophilized polymer gas-repelling material includes the polymer polytetrafluoroethylene (PTFE).

[0078] Furthermore, hydrophilic polymers may also repel hydrogen gas due to their ability to form a blocking hydration layer. In some embodiments, the hydrophilic polymer gas-repelling material may include, but is not limited to, polyacrylate (PA), polyacrylic acid (PAA), polyvinyl alcohol (PVA), polyacrylamide (PAM), poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA), poly(N,N-dimethylacrylamide) (PDMA), polyethylene glycol (PEG), polyethylenimine (PEI), polylysine (PLL), poly(lysine isophthalamide) (PLP), poly(2- hydroxyethyl methacrylate) (PHEMA), polyvinylpyrrolidone (PVP), polysaccharides, block copolymers thereof, cross-linked version thereof, derivatives thereof, or any combination thereof. Each possibility is a separate embodiment.

[0079] In some embodiments, when the gas-repelling material is metal oxide, the material may be selected from, but is not limited to, TixOy, IrxOy, RuxOy, NixOy, FexOy, CoxOy, MnxOy, and any combination thereof, wherein x and y can be any integer between 1 to 4, 1 to 3, or 1 to 7. Each possibility is a separate embodiment. In some embodiments, the gas-repelling material metal oxide may be selected from, but is not limited to, TiO, Ti20s, TisOs, TiCE, T CE, TisOs, IrCE, I CE, RuCE, RuCE, NiO, N12C , FeO, Fe2C , FesCE, CoO, C02CE, C03CE, MnO, MmCE, MnCE, MmCE, M CE, and any combination thereof. In some embodiments, the gas-repelling material metal oxide is TiCE. Each possibility is a separate embodiment.

[0080] In some embodiments, when the gas-repelling material is a ceramic material, the material may include, but is not limited to, alumina, silica, zirconia, titania, boron nitride, or any combination thereof. Each possibility is a separate embodiment.

[0081] In some embodiments, the hydrophilized graphene gas-repelling material may be graphene oxide.

[0082] In some embodiments, the hydrophilized graphite gas-repelling material may be oxidized graphite.

[0083] In some embodiments, the gas-repelling material is superhydrophilic Poly dimethyl siloxane (PDMS) tubes. In some embodiments, the hydrogel gas-repelling material may include, but is not limited to, a glutaraldehyde-cross-linked (super)aerophobic Ml 3 virus, polyethyleneimine (PEI), or a combination thereof. In some embodiments, the hydrogel gas-repelling material is glutaraldehyde-cross-linked (super)aerophobic nanofibrillar structure hydrogel.

[0084] There is provided herein, in accordance with some other embodiments, a fluid-routing element for use in an electrochemical reactor, the fluid-routing element includes a flow-field channel(s), wherein the flow-field channel(s) includes a gas-repelling layer having a surface roughness of at least about 5-fold higher compared to a surface roughness of the forefront of the element facing a reaction zone of the electrochemical reactor.

[0085] There is provided herein, in accordance with some other embodiments, a fluid-routing element for use in an electrochemical reactor, the fluid-routing element includes a flow-field channel(s), wherein the flow-field channel(s) are at least partially coated with a gas-repelling layer having a surface roughness of at least about 5-fold higher compared to a surface roughness of the forefront of the element facing a reaction zone of the electrochemical reactor.

[0086] According to some embodiments, the surface roughness of the gas-repelling layer at the flow-field channels is at least about 2-fold higher compared to the surface roughness of the forefront of the element, for example, at least about 2-5-fold, at least about 3-6, at least about 4-8-fold, at least about 5-10-fold, at least about 10-15-fold, or at least about 15-50-fold, higher compared to the surface roughness of the forefront of the element. Each possibility is a separate embodiment.

[0087] According to some embodiments, the surface roughness of the gas-repelling layer is in the microroughness range. According to some embodiments, the surface roughness, Rq or Ra, of the gas-repelling layer is between 0.1-10 pm, for example, between 0.1-8 pm, between 0.1- 5 pm, or between 1-5 pm. Each possibility is a separate embodiment.

[0088] As used herein, in accordance with some embodiments, the term “roughness” refers to small-scale variations in height and texture on a surface, characterized by features such as peaks, valleys, and other irregularities. The roughness may be quantified using parameters such as average roughness (Ra), root mean square roughness (Rq), and peak-to-valley height (Rz).

[0089] As used herein, in accordance with some embodiments, the term “roughened surface” refers to a surface that has been made rougher than it was before (i.e., before applying / making the (rough) gas-repelling layer). In some embodiments, the roughened surface is rougher by at least about 2-fold, for example, by at least about 2-5-fold, by at least about 3-6, by at least about 4-8-fold, by at least about 5-10-fold, by at least about 10-15-fold, or by at least about 15- 50-fold as compared to as it was before the roughening. Each possibility is a separate embodiment.

[0090] According to some other embodiments, the flow-field channels are roughened in at least about 25% of the overall flow-field channels’ surface area, for example, about 25-35%, about 35-45%, about 45-55%, about 55-65%, about 65-75%, about 75-85%, or about 89-95% of the flow-field channels’ surface area. Each possibility is a separate embodiment.

[0091] According to some embodiments, the forefront of the element is conductive. The forefront of the element remains conductive to allow electrochemical activity.

[0092] According to some further embodiments, the channels of the flow-field are modified physically and / or chemically to increase the surface area thereof. According to some embodiments, the channels of the flow-field are modified with a gas-repelling layer. According to some embodiments, the gas-repelling layer enhances the surface roughness of the channels. According to some embodiments, the high surface roughness of the channels enhances gas repelling. According to some embodiments, the high surface roughness of the channels enhances gas repelling by improving gas bubble detachment.

[0093] The rough surface may further promote turbulent flow, according to some embodiments. In some embodiments, the induced turbulent flow improves the mixing of the electrolyte and the delivery of reactants while aiding in the removal of gas bubbles.

[0094] According to some embodiments, the channels’ surface of the element includes a gasrepelling layer that is porous, patched, granulated, nano-structured, micro-structured, spattered, or sanded. Each possibility is a separate embodiment.

[0095] According to some embodiments, the surface of the channels’ gas-repelling layer is characterized by roughness that is higher by at least 20%, at least 30%, at least 40%, at least 50%, at least 80%, at least 100%, at least 200%, at least 500%, or at least 1000%, compared to the surface roughness of the forefront. Each possibility is a separate embodiment. According to some embodiments, the fluid-routing element is conductive. In some embodiments, the element is made of, or includes, at least a partially conductive material.

[0096] In some embodiments, the fluid-routing element body includes a material selected from, but is not limited to, titanium, gold, iron, nickel, copper, aluminum, graphite, stainless steel, alloys thereof, a composite of organic-inorganic material thereof, and any combination thereof. Each possibility is a separate embodiment.

[0097] According to some embodiments, the flow-field channels are engraved to form an engraved flow field.

[0098] In some embodiments, the engraved flow-field has a geometry selected from, but is not limited to, serpentine, multi-channel serpentine, parallel channels, cascade channels, pin-type, and any combination thereof. Each possibility is a separate embodiment.

[0099] According to some embodiments, the flow-field of the fluid-routing element is in a form selected from, but is not limited to, woven (metal) wire (cloth), expanded mesh, monoliths of porous sintered powder, and a combination thereof. Each possibility is a separate embodiment.

[0100] In some embodiments, the flow field channels may be sintered.

[0101] According to some embodiments, the flow-field channels’ geometry may include, but is not limited to, rectangular channels, serpentine channels, parallel channels, or trapezoidal channels. Each possibility is a separate embodiment.

[0102] According to some embodiments, the electrochemical reactor is an electrolytic cell.

[0103] According to some embodiments, the herein disclosed electrolytic cell is selected from, but is not limited to, silver plating cell, gold plating cell, copper electrorefining cell, water electrolysis cell (electrolyzer), chlor-alkali cell, aluminum anodizing cell, hall-heroult cell (aluminum production), magnesium production cell, electrolytic cleaning cell, hydrogen peroxide production cell, and kolbe electrolysis cell. Each possibility is a separate embodiment. According to some embodiments, the electrolytic cell is an electrolyzer.

[0104] As used herein, in accordance with some embodiments, the term “electrolyzer” or “electrolytic cell” refers to a device designed to carry out electrolysis, particularly the splitting of water into hydrogen and oxygen gases. While it is a type of electrolytic cell, the term “electrolyzer” is used in the context of producing hydrogen for fuel or other industrial uses. The electrolytic cell may also operate as another type of electrochemical cell, depending on the system configuration and inputs.

[0105] According to some embodiments, the herein disclosed electrolyzer is selected from, but not limited to, proton exchange membrane (PEM) water electrolyzer, alkaline membrane water electrolyzer, solid oxide electrolyzer, anion exchange membrane electrolyzer, high-pressure electrolyzer, solar-powered electrolyzer, photoelectrochemical electrolyzer, bipolar plate electrolyzer, and decoupled water electrolyzer. Each possibility is a separate embodiment. According to some embodiments, the electrolyzer is a proton exchange membrane (PEM) water electrolyzer (PEMWE).

[0106] In some embodiments, the decoupled water electrolyzer may include, but is not limited to, mediated electrochemical water splitting, a bipolar membrane electrolyzer, or modular electrolyzer system. Each possibility is a separate embodiment.

[0107] As used herein, in accordance with some embodiments, the term “proton exchange membrane water electrolyzer” or “PEMWE” refers to a device that uses electrical energy to split water into hydrogen and oxygen gases through electrolysis, typically utilizing a solid polymer membrane as the electrolyte. The membrane allows protons (H+ions) to pass through while blocking electrons and gases, enabling efficient separation of hydrogen and oxygen, according to some embodiments. At the anode, water is oxidized to produce oxygen, protons, and electrons, while at the cathode, protons are reduced to form hydrogen gas.

[0108] According to some embodiments, the reaction zone includes, but is not limited to, a separator, a gas diffusion layer (GDL), a porous transport layer (PTL), a catalyst layer, or any combination thereof. Each possibility is a separate embodiment.

[0109] According to some embodiments, the separator is selected from, but is not limited to, a proton exchange membrane (PEM), an anion exchange membrane, an ion-solvating membrane, a bi-polar membrane, and a diaphragm. Each possibility is a separate embodiment.

[0110] According to some embodiments, the gas diffusion layer (GDL) is a porous, conductive material that facilitates efficient water transport and distribution to the catalyst layer, as well as the removal of gas products away from the catalyst layer, while also providing a conductive pathway for electrons to enhance the electrical efficiency of the electrolyzer. The GDL, which can be made of carbon-based materials (e.g., carbon paper) or metallic materials (e.g., sintered titanium), may be coated with hydrophobic substances (e.g., PTFE) to optimize water management and ensure structural integrity and durability of the electrolyzer cell.

[0111] According to some embodiments, the electrochemical reactor includes at least two electrodes. According to some embodiments, the at least two electrodes include an anode. The anode may be an oxygen evolution reaction (OER) electrode. According to some embodiments, the at least two electrodes include a cathode. The cathode may be a hydrogen evolution reaction (HER) electrode.

[0112] According to some embodiments, the anode includes or is associated with the fluidrouting element. According to some embodiments, an anode current collector includes, is associated with, or is the fluid-routing element. According to some embodiments, the anode current collector may include a material selected from, but is not limited to, iridium oxide (IrCh), ruthenium oxide (RuCE), nickel oxide (NiO), cobalt oxide (CoO), iron oxide (Fe2O3), and any combination thereof. Each possibility is a separate embodiment. According to some embodiments, the anode current collector may include titanium oxide (TiCE). According to some embodiments, the anode current collector may include a composition of mixed-metal oxide. According to some embodiments, the anode current collector may include Ti(7o-x%)Ch- M(X%)02, where M stands for one or more of: Sn, Nb, Ir (e.g., Mixed Metal Oxide MMO). Each possibility is a separate embodiment. According to some embodiments, the anode current collector may include Ti / Ru(3o%)CE.

[0113] According to some embodiments, the cathode includes or is associated with the fluidrouting element. According to some embodiments, the cathode current collector includes, is associated with, or is the fluid-routing element. According to some embodiments, the cathode current collector may include a material selected from, but is not limited to, platinum, platinumruthenium alloy, platinum-palladium alloy, platinum-iridium alloy, platinum-nickel alloy, platinum on a carbon support, platinum on graphene, platinum on carbon nanotubes, platinumgroup metal with carbides / nitrides / phosphides, nickel, nickel-molybdenum alloy, nickel-iron alloy, nickel-cobalt alloy, nickel -graphene composite, nickel-carbon nanotubes composite, nickel phosphide, nickel foam, titanium grade 1, titanium grade 2, and any combination thereof. Each possibility is a separate embodiment. According to some embodiments, the electrode is porous. According to some embodiments, the electrode has a roughness at the nanoscale. According to some embodiments, the electrode has a roughness at the microscale.

[0114] According to some embodiments, the electrode is further supported by a conductive material. The conductive material may be selected from, but is not limited to, carbon paper or titanium mesh. Each possibility is a separate embodiment.

[0115] According to some embodiments, the herein disclosed fluid-routing element is capable of conducting an electrical current to, and from, the reaction zone. According to some embodiments, the fluid-routing element collects and distributes electrical current to and from the electrodes. According to some embodiments, the fluid-routing element conducts electrical current from a power supply to the catalyst layers / electrodes.

[0116] According to some embodiments, the fluid-routing element is a current collector with a flow-field.

[0117] According to some embodiments, the herein disclosed fluid-routing element is capable of routing / removing a gaseous product from the reaction zone. According to some embodiments, the fluid-routing element is configured to distribute the gaseous product away from the fluid-routing element. According to some embodiments, the fluid-routing element is configured to distribute the gaseous product away from the reaction zone.

[0118] According to some embodiments, the fluid-routing element further mediates the distribution of liquid.

[0119] According to some embodiments, the gaseous product is hydrogen.

[0120] According to some embodiments, the gaseous product is oxygen.

[0121] According to some embodiments, the herein disclosed fluid-routing element is associated with the cathode. According to some embodiments, the fluid-routing element is associated with the hydrogen-evolving reaction (HER) electrode.

[0122] According to some embodiments, the herein disclosed fluid-routing element is associated with the anode. According to some embodiments, the fluid-routing element is associated with the oxygen-evolving reaction (OER) electrode. According to some embodiments, the herein disclosed fluid-routing element is for use as a current collector in a mono-polar or bipolar electrode configuration.

[0123] According to some embodiments, the herein disclosed fluid-routing element is for use as a current collector. According to some embodiments, the fluid-routing element is for use as a current collector including a flow-field. According to some embodiments, the flow-field includes channels and / or porous structures. In some embodiments, the flow-field facilitates the effective removal of gases (hydrogen and oxygen) generated during electrolysis.

[0124] According to some embodiments, the use of the herein disclosed fluid-routing element enhances gas removal efficiency. According to some embodiments, the use of the herein disclosed (partially) coated fluid-routing element enhances gas removal efficiency. According to some embodiments, the use of the herein disclosed surface-modified fluid-routing element, including the gas-repelling layer, enhances gas removal efficiency. According to some embodiments, the use of the herein disclosed fluid-routing element reduces the gas adsorption at the electrode / current collector.

[0125] According to some embodiments, the use of the herein disclosed fluid-routing element lowers ohmic resistance in the electrode / current collector. According to some embodiments, the use of the herein disclosed fluid-routing element lowers the overall resistance in the electrochemical reactor.

[0126] According to some embodiments, the specific energy consumption of the electrochemical reactor, including the herein disclosed fluid-routing element, is less than about 5.0 kWh / Nm3, for example, between 0.5-5 kW / Nm3, between 0.5-4.5 kW / Nm3, between 0.5- 4.3 kW / Nm3, between 0.5-4.0 kW / Nm3, between 0.5-3.5 kW / Nm3, between 1.0-3.0 kW / Nm3, between 1.0-2.0 kW / Nm3, or between 1.0-1.5 kW / Nm3Each possibility is a separate embodiment.

[0127] According to some embodiments, the cell voltage efficiency of the electrochemical reactor, including the herein disclosed fluid-routing element, is at least about 65%, for example between 65-80%, between 68-80%, between 70-80%, between 70-78%, between 78-95%, or between 83-93% Each possibility is a separate embodiment.

[0128] According to some embodiments, the herein disclosed fluid-routing element protects the surface thereof against hydrogen embrittlement. According to some embodiments, the fluid-routing element protects the electrode against hydrogen embrittlement. According to some embodiments, the fluid-routing element thereby minimizes surface damage at the flow field. According to some embodiments, the fluid-routing element is capable of prolonging the life span of an electrode in general, and a current collector / flow field in particular. According to some embodiments, the fluid-routing element is capable of enhancing the overall durability and efficiency of the electrochemical reactor.

[0129] According to some embodiments, the lifetime of the electrode including the fluidrouting element is at least about 5,000 h, for example, between 10,000-15,000 h, between 15,000-20,000 h, between 15,000-22,000 h, between 22,000-25,000 h, between 25,000-27,000 h, between 27,000-30,000 h, between 30,000-32,000 h, between 32,000-35,000 h, between 35,000-40,000 h, between 40,000-55,000 h, between 55,000-80,000 h, between 80,000- 100,000 h, or between 100,000-130,000 h. Each possibility is a separate embodiment.

[0130] According to some embodiments, the current density at the electrode surface, including the herein disclosed fluid-routing element, is between 0.6-10.0 A / cm2, for example, between 1-10 A / cm2, between 1-5 A / cm2, or between 5-10 A / cm2. Each possibility is a separate embodiment.

[0131] There is provided herein, in accordance with some embodiments, a method for producing a fluid-routing element disclosed herein, the method includes obtaining a fluid-routing element comprising flow-field channels ; applying a gas-repelling material layer on the fluid-routing element; and removing the applied layer from the forefront of the element , such that the flow-field channels include the gas-repelling material layer, and wherein the forefront of the element is essentially devoid of the gas-repelling material layer.

[0132] There is provided herein, in accordance with some embodiments, a method for producing a fluid-routing element disclosed herein, the method includes obtaining a current collector including flow-field channels ; applying a gas-repelling layer on the current collector; and removing the applied layer from the forefront of the current collector , to obtain the fluid-routing element, such that the flow-field channels include the gas-repelling layer, and wherein the forefront of the element is essentially devoid of the gas-repelling layer.

[0133] There is provided herein, in accordance with some embodiments, a method for producing the partially coated fluid-routing element disclosed herein, the method including: providing a current collector including flow-field channels; applying a gas-repelling material layer on the current collector, to produce a coated fluid-routing element; and removing the applied material layer from the forefront of the current collector, to obtain the fluid routing element, such that the flow-field channels remain at least partially coated with the gas-repelling material, and wherein the forefront of the element is essentially uncoated.

[0134] A reference is now made to FIG. 2, which schematically illustrates a flowchart of a method for producing the partially coated fluid-routing element. As shown in FIG. 2, the production method 200 includes step 210, in which a current collector including a flow-field is provided, according to some embodiments. The flow field can be provided by patterning a conductive substrate. In an optional step 220, the surface of the substrate is pre-treated. The pre-treatment facilitates the application of the gas-repelling material layer in the next step. Examples of types of pre-treatment may include, but not limited to, oxidation, sanding, acidification, or irradiation with plasma or UV-ozone. In step 230, a gas-repelling (material) layer is applied on the surface of the current collector, according to some embodiments. An example of the gas-repelling layer may be a hydrophilized polymer (e.g., hydrophilized PTFE) layer or a roughened layer of the current collector surface (e.g., superaerophobic micro-nano hierarchical TiCb structures coating the channels). In step 240, the gas-repelling (material) layer is removed from the forefront of the current collector, to obtain the fluid routing element, such that the flow-field channels remain coated with the gas-repelling (material) layer and the forefront of the element is essentially uncoated with the gas-repelling material layer, according to some embodiments. The removal of the gas-repelling material layer may be facilitated by polishing the ribs of the flow-fi el d / forefront surface of the element. Sanding and buffing are examples of polishing techniques that may be utilized, in some embodiments. According to some embodiments, the obtained fluid-routing element is produced by forming first a patterned channel morphology on, or in, a substrate. In some embodiments, the patterned morphology is as disclosed herein. The patterned morphology inherently includes channeled pathways. The channels are formed between / within the patterned form of the herein disclosed engraved / non-engraved flow fields.

[0135] According to some embodiments, the formation of the patterned channels includes a technique selected from, but is not limited to, electro-deposition, electroless-deposition, (photo)lithography, sputtering, chemical vapor deposition, spin coating, film coating, printing, spraying, etching, diamond engraving, CNC engraving, photochemical engraving, rotary engraving, laser engraving, and any combination thereof. Each possibility is a separate embodiment.

[0136] According to some embodiments, the current collector is surface-pre-treated prior to applying the gas-repelling layer. According to some embodiments, the pre-treatment is cleaning the surface of the element to enhance the adhesion of the surface to the gas-repelling material. The cleaning removes a natural oxide layer from the surface. According to some embodiments, the pre-treatment may include a technique selected from, but is not limited to, sandblasting, plasma, UV / Ozone, acid, base, etching, washing, oxidation, and any combination thereof. Each possibility is a separate embodiment. According to some embodiments, the pretreatment is sandblasting. According to some embodiments, the pre-treatment is etching with an acid.

[0137] According to some embodiments, the application of the gas-repelling material is facilitated by using a technique selected from, but not limited to, electro-deposition, thermal deposition, chemical vapor deposition, physical vapor deposition, sputtering, spraying, layer- by-layer deposition, brushing, spin coating, pre-made film layer coating, printing, dip coating, spray coating, and any combination thereof. Each possibility is a separate embodiment.

[0138] In some embodiments, the application of the gas-repelling material may be followed by a polymerization step. In some embodiments, the application of the gas-repelling material may be followed by a curing step.

[0139] According to some embodiments, the application of the gas-repelling material may further include hydrophilizing the applied material. According to some embodiments, the hydrophilization of the applied material induces properties of gas repellence in the material. In some embodiments, hydrophilization may be performed before applying the gas-repelling material to the surface. In some other embodiments, the hydrophilization may be performed after applying the material to the surface.

[0140] In some embodiments, hydrophilizing the applied material may include a chemical treatment such as acid treatment and / or oxidation treatment. In some embodiments, oxidizing agents used for the oxidation may include, but are not limited to, for example, sodium naphthalenide or sodium-naphthalene complex.

[0141] In some embodiments, hydrophilizing the applied material may include irradiating the material with plasma (e.g., by utilizing gases such as nitrogen, oxygen, or air) to oxidize the surface thereof.

[0142] In some embodiments, hydrophilizing the applied material may include irradiation with an ion beam (e.g., Ar+or O2+). In some embodiments, exposing the element’s surface to ion beam irradiation induces structural changes within the applied material that may result in hydrophilic bulk properties. This treatment induces oxidative degradation of hydrophobic polymers, resulting in the formation of oxygen-containing functional groups, including hydroxyl (-OH) and carboxyl (-COOH).

[0143] In some embodiments, hydrophilizing the applied material may include further applying a hydrophilic polymer, such as PVA or PAA, to obtain a water-absorbent layer. In some embodiments, the applied hydrophilic polymer may be any of the herein-disclosed hydrophilic polymers. According to some embodiments, hydrophilizing the applied material may include further applying a ceramic material, for example, titania, silica, zirconia, or boron nitride. Each possibility is a separate embodiment,

[0144] In some embodiments, any of the hydrophilizing methods detailed herein may be combined by any means to obtain the applied hydrophilized material having a gas-repellence property.

[0145] According to some embodiments, the removal of the gas-repelling (material) layer from the forefront of the element includes, but is not limited to, grinding, etching, sandblasting, sanding, buffing, leaching, oxidation, scraping, polishing, or any combination thereof. Each possibility is a separate embodiment. There is provided herein, in accordance with some embodiments, a method for producing the fluid-routing element disclosed herein, the method includes: providing a current collector including flow-field channels; roughening the current collector, to produce a rough gas-repelling layer on the surface of the current collector; and re-smoothing the forefront of the current collector (i.e., removing the rough gasrepelling layer therefrom), to obtain the fluid routing element, wherein the surface of the flow-field channels remains rough (i.e., coated with the rough gas-repelling layer) and the forefront of the element is essentially not rough (i.e., essentially uncoated).

[0146] According to some embodiments, the forefront of the element is essentially not rough. As used herein, in accordance with some embodiments, the term “essentially not rough” or “essentially uncoated” refers to the forefront’s surface upon smoothing / polishing it. According to some embodiments, the “essentially not rough” surface is characterized by a roughness that is lower by at least about 20% than the roughness of the channels’ surface, for example, by at least about 50%, by at least about 80%, by at least about 100%, by at least about 500%, or by at least about 1000%. Each possibility is a separate embodiment.

[0147] According to some embodiments, the channels of the flow-field are surface-modified with a rough gas-repelling layer. According to some further embodiments, the channels of the flow-field are modified physically and / or chemically to increase the surface area thereof.

[0148] According to some embodiments, the gas-repelling layer enhances the surface roughness of the channels. According to some embodiments, the physical and / or chemical method for roughening the surface includes, but is not limited to, etching, sanding, and / or anodizing. Each possibility is a separate embodiment.

[0149] According to some embodiments, the surface roughness of the channels is enhanced by etching.

[0150] According to some embodiments, the surface roughness of the channels is enhanced by etching using a technique selected from, but is not limited to, acid treatment, base treatment, laser beam treatment, electron beam treatment, Plasma etching (“dry etching”), and any combination thereof. Each possibility is a separate embodiment. In some embodiments, the surface roughness of the channels is enhanced by etching its surface using an acid. According to some embodiments, the gas-repelling layer is, thus, an acid- etched surface characterized by micro-scale roughness.

[0151] According to some embodiments, the surface roughness of the channels is enhanced by anodizing the surface thereof. In some embodiments, the surface roughness of the channels is enhanced by anodizing the surface via electrochemical oxidation. In some embodiments, the surface roughness of the channels is enhanced by electrochemically anodizing the surface in the presence of an acid. According to some embodiments, the anodizing of the surface of the channels produces, thus, a (super)aerophobic gas-repelling layer. According to some embodiments, the anodized surface is characterized by (super)aerophobic micro-nano hierarchical metal oxide structures.

[0152] In some embodiments, the metal, to be anodized, is selected from, but not limited to, titanium, aluminum, and any combination thereof. Each possibility is a separate embodiment. According to some embodiments, the anodized surface is a gas-repelling layer having superaerophobic micro-nano hierarchical TiCb structures.

[0153] According to some embodiments, the inclusion of the gas-repelling material layer in the flow-field channel(s) is in a form selected from, but not limited to, added gas-repelling material, added gas-repelling material that is pre / post-modified (e.g., hydrophilization, polymerization), added gas-repelling material coating layer, gas-repelling material (layer) coating made by modifying the element, added gas-repelling material coating layer which is rough, roughen gas-repelling layer made by modifying the element’s surface, and any combination thereof. Each possibility is a separate embodiment.

[0154] The following examples are presented in order to more fully illustrate some embodiments of the invention. They should, in no way be construed, however, as limiting the broad scope of the invention. One skilled in the art can readily devise many variations and modifications of the principles disclosed herein without departing from the scope of the invention. EXAMPLES Preparation of a fluid-routing element with an aerophobic layer as the gasrepelling layer

[0155] A titanium plate with dimensions of 50 x 100 x 2 mm undergoes subtractive manufacturing techniques, such as engraving, to create a flow field of parallel channels on its surface. After engraving, the plate is sanded to remove the natural oxide layer from the substrate. The engraved plate is then etched in boiling concentrated hydrochloric acid (6M HC1) for 5 minutes to increase surface roughness and improve the adhesion of the polymer layer. A suspension of PTFE 60% is used to coat the flow channels by brushing the suspension onto them. The coated plate is sintered in a furnace at 300°C for 30 minutes, followed by slow cooling to room temperature. After the plate cools down, the coated substrate is subjected to an ethanol wash and then an aqueous suspension of polyvinyl alcohol (PVA) 10% is brushed onto the PTFE layer. The PVA-coated PTFE is then immersed in a glutaraldehyde solution to induce crosslinking of the PVA polymer chains. Finally, the crosslinked PVA-coated PTFE is rinsed with deionized water and dried at 60°C to remove residual reagents and solvent. After the plate cools down, excess layers of polymers are removed using sandpaper to ensure the forefront of the plate is exposed and conductive. Conductivity of the fluid-routing element

[0156] The PTFE-Ti composite's resistance is assessed using an Ohm-meter to ensure the conductivity of the forefront of the element and to characterize the coating layer. Wettability

[0157] The hydrophobic or hydrophilic properties of the samples are tested by the sessile drop method, this method enables us to measure the optical contact angle (CA), which is the angle formed between the drop's baseline and the tangent at its contact point with the surface. For a hydrophilic coating of the element, the CA is lower compared to a non-coated element.

[0158] T1 A fluid-routing element for PEMWE that does not include a gas-repelling layer (reference system)

[0159] Fabrication of PEM cell with two monopolar electrodes having a surface area of 10 cm2each, is performed. The cell includes catalysts-coated Nafion 117 membrane. The membrane is spray-coated with IrCb (2.0 mg of IrCb / crn2) on the anode side and 60% platinum on carbon (0.5 mg of Pt / cm2) on the cathode side. An anode porous transport layer (Ti fleece - sintered fiber) and a cathode porous transport layer (carbon paper) are hot-pressed to the catalysts- coated membrane to assemble a membrane electrode assembly (MEA). The MEA is sandwiched between two current collectors using screws and nuts. The two current collectors include Ti blocks equipped with fittings for recirculation of fluids and gas release, connectors for wiring of the cell, holes for screws, heating cartridges, PTFE foil gaskets for sealing the cell, and engraved flow-fields for supplying water to electrodes and release of gases from the electrodes in the cell.

[0160] System #1 (reference, control system) - In this case, both of the flow-fields are not coated with a gas-repelling layer. Both flow fields have mirror-like polished channels.

[0161] An electrochemical test includes polarization of the cell at different voltages (V) and recording the steady-state currents (I). The I-V curves are collected at varied temperatures and water flow rates. While using a combination of I-V experiments with periodical Electrochemical Impedance Spectroscopy (EIS) measurements (conducted at varied bias voltage and bias current modes) the effect of bubbles release on energy consumption is evaluated. - A fluid-routing element for PEMWE having a rough layer as the gasrepelling layer

[0162] Fabrication of PEM cell with two monopolar electrodes having a surface area of 10 cm2each, is performed. The cell includes catalysts-coated Nafion 117 membrane. The membrane is spray-coated with IrCb (2.0 mg of IrCb / crn2) on the anode side and 60% platinum on carbon (0.5 mg of Pt / cm2) on the cathode side. An anode porous transport layer (Ti fleece) and a cathode porous transport layer (carbon paper) are hot-pressed to the catalysts-coated membrane to assemble a membrane electrode assembly (MEA). The MEA is sandwiched between two current collectors using screws and nuts. The two current collectors include Ti blocks equipped with fittings for recirculation of fluids and gas release, connectors for wiring of the cell, holes for screws, heating cartridges, PTFE foil gaskets for sealing the cell, and engraved flow -fields for supplying water to electrodes and release of gases from the electrodes in the cell.

[0163] System #2 - In this case, both of the flow fields have a high surface area. Both of the flow-fields have channels with microroughness, i.e., about 0.5-5 pm Ra . To this aim, the flowfields in Ti end-plates are etched in 6 M boiling HC1 for 5 minutes to increase the roughness of the channels and produce channels having microroughness characteristics. The ribs of the channels are consequently polished to a mirror-like state.

[0164] The I-V & EIS electrochemical tests are performed (as in Example 4), and the results of the reference and the high surface area systems are compared to confirm lower energy consumption due to a more effective release of bubbles from the cell of the rougher system. Fluid-routing element for PEMWE having a rough aerophobic layer as the gas-repelling layer

[0165] Fabrication of PEM cell with two monopolar electrodes having a surface area of 10 cm2each, is performed. The cell includes catalysts-coated Nafion 117 membrane. The membrane is spray-coated with IrCF (2.0 mg of IrCh / cm2) on the anode side and 60% platinum on carbon (0.5 mg of Pt / cm2) on the cathode side. An anode porous transport layer (Ti fleece) and a cathode porous transport layer (carbon paper) are hot-pressed to the catalysts-coated membrane to assemble a membrane electrode assembly (MEA). The MEA is sandwiched between two current collectors using screws and nuts. The two current collectors include Ti blocks equipped with fittings for recirculation of fluids and gas release, connectors for wiring of the cell, holes for screws, heating cartridges, PTFE foil gaskets for sealing the cell, and engraved flow -fields for supplying water to electrodes and release of gases from the electrodes in the cell.

[0166] System #3 - In this case, both of the flow-fields have channels with superaerophobic metal-oxide layer. To this aim, the flow-fields in Ti end-plates are anodized in pH 3 HNO3 solution at 20-80 V to obtain superaerophobic micro-nano hierarchical TiCF structures on the surface of channels. The ribs of the channels are polished afterward to a mirror-like state.

[0167] The I-V & EIS electrochemical tests are performed (as in Example 4), and the results of the reference and the superaerophobic systems are compared to confirm lower energy consumption due to a more effective release of bubbles from the cell of the superaerophobic system. Fluid-routing element having an aerophobic layer as the gas-repelling layer

[0168] Fabrication of PEM cell with two monopolar electrodes having a surface area of 10 cm2each, is performed. The cell includes catalysts-coated Nafion 117 membrane. The membrane is spray-coated with IrCb (2.0 mg of IrCb / crn2) on the anode side and 60% platinum on carbon (0.5 mg of Pt / cm2) on the cathode side. An anode porous transport layer (Ti fleece) and a cathode porous transport layer (carbon paper) are hot-pressed to the catalysts-coated membrane to assemble a membrane electrode assembly (MEA). The MEA is sandwiched between two current collectors using screws and nuts. The two current collectors include Ti blocks equipped with fittings for recirculation of fluids and gas release, connectors for wiring of the cell, holes for screws, heating cartridges, PTFE foil gaskets for sealing the cell, and engraved flow -fields for supplying water to electrodes and release of gases from the electrodes in the cell.

[0169] System #4 - In this case, both of the flow-fields have superaerophobic hydrogel layers. To this aim, the flow-fields in Ti end-plates are coated with a superaerophobic Ml 3 virus (glutaraldehyde-cross-linked) hydrogel layer. The ribs of the channels are polished afterward to a mirror-like state.

[0170] The I-V & EIS electrochemical tests are performed (as in Example 4), and the results of the reference and the superaerophobic hydrogel systems are compared to confirm lower energy consumption due to a more effective release of bubbles from the cell of the superaerophobic system. A fluid-routing element for AMWE that does not include a gas-repelling layer (reference system)

[0171] An alkaline membrane water electrolysis (AMWE) cell with two monopolar electrodes having a surface area of 10 cm2each is fabricated. The cell includes Sustainion® 37-50 membrane spray-coated with IrCh (2.0 mg of IrCh / cm2) on the anode side and 60% platinum on carbon (0.5 mg of Pt / cm2) on the cathode side. The anode porous transport layer (stainless steel cloth) and cathode porous transport layer (stainless steel cloth) are hot-pressed to the catalysts-coated membrane to assemble a membrane electrode assembly (MEA). The MEA is sandwiched between two current collectors using screws and nuts. Two current collectors include gold-coated Ti blocks equipped with fittings for recirculation of fluids (IM KOH) and gas release, connectors for wiring of the cell, holes for screws, PTFE foil gaskets for sealing the cell, heating cartridges, and engraved flow-fields for supply of water to electrodes and release of gases from the electrodes in the cell.

[0172] System #5 - In this case, both of the flow-fields are not coated with a gas repelling layer. Both of the flow-fields have mirror-like gold-coated polished channels.

[0173] An electrochemical test includes polarization of the cell at different voltages (V) and recording the steady-state currents (I). The I-V curves are collected at varied temperatures and water flow rates. While using a combination of I-V experiments with periodical Electrochemical Impedance Spectroscopy (EIS) measurements (conducted at varied bias voltage and bias current modes) the effect of bubbles release on energy consumption is evaluated.

[0174] 9 A fluid-routing element for AMWE having a superaerophobic hydrogel layer as a gas repelling layer

[0175] An alkaline membrane water electrolysis (AMWE) cell with two monopolar electrodes having a surface area of 10 cm2each is fabricated. The cell includes Sustainion® 37-50 membrane spray-coated with IrCh (2.0 mg of IrCh / cm2) on the anode side and 60% platinum on carbon (0.5 mg of Pt / cm2) on the cathode side. The anode porous transport layer (stainless steel cloth) and cathode porous transport layer (stainless steel cloth) are hot-pressed to the catalysts-coated membrane to assemble a membrane electrode assembly (MEA). The MEA is sandwiched between two current collectors using screws and nuts. Two current collectors include gold-coated Ti blocks equipped with fittings for recirculation of fluids (IM KOH) and gas release, connectors for wiring of the cell, holes for screws, PTFE foil gaskets for sealing the cell, heating cartridges, and engraved flow-fields for supply of water to electrodes and release of gases from the electrodes in the cell.

[0176] System #6 - In this case both, of the flow-fields have superaerophobic hydrogel coating.

[0177] To this aim, the flow-fields in Ti endplates are coated with superaerophobic polyethyleneimine (PEI) hydrogel. The ribs of the channels are polished afterward to a mirror-like state. The I-V & EIS electrochemical tests are performed (as in Example 8), and the results of the reference and the superaerophobic hydrogel systems are compared to confirm lower energy consumption due to a more effective release of bubbles from the cell of the superaerophobic system.

Claims

CLAIMS1. A fluid-routing element for use in an electrochemical reactor, the fluid-routing element comprises flow-field channel(s), wherein the flow-field channel(s) comprises a gasrepelling layer, and wherein a forefront of the element facing a reaction zone of the electrochemical reactor is essentially devoid of the gas-repelling layer.

2. The fluid-routing element of claim 1, wherein the gas-repelling layer comprises hydrophilized graphene, hydrophilized graphite, hydrophilic polymer, hydrophilized polymer, polyelectrolyte, metal oxide, ceramic material, hydrogel, or any combination thereof.

3. The fluid-routing element of claim 2, wherein the hydrophilized polymer comprises polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), epoxy, polypropylene (PP), polyethylene, polystyrene (PS), polyvinylchloride (PVC), polydimethylsiloxane (PDMS), polyesters, polyurethanes, polycaprolactone, polypropylene oxide (PPO), block copolymers thereof, cross-linked version thereof, chemical modification thereof, or any combination thereof.

4. The fluid-routing element of any one of claims 2 and 3, wherein the hydrophilic polymer comprises polyacrylate (PA), polyvinyl alcohol (PVA), polyacrylamide (PAM), poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA), poly(N,N- dimethylacrylamide) (PDMA), polyethylene glycol (PEG), polyethylenimine (PEI), polylysine (PLL), poly(lysine isophthalamide) (PLP), poly(2-hydroxyethyl methacrylate) (PHEMA), polyvinylpyrrolidone (PVP), polysaccharides, block copolymers thereof, cross-linked version thereof, derivatives thereof, or any combination thereof.

5. The fluid-routing element of any one of claims 1-4, wherein the gas-repelling layer comprises, or is, a roughened surface layer.

6. The fluid-routing element of claim 5, wherein a surface roughness of the roughened surface layer at the flow-field channel(s) is at least about 5-fold higher compared to a surface roughness of the forefront of the element.

7. The fluid-routing element of any one of claims 1-6, wherein the flow-field channels are engraved to form an engraved flow field.

8. The fluid-routing element of claim 7, wherein the engraved flow field has a geometry comprising: serpentine, multi-channel serpentine, parallel channels, cascade channels, pin-type, or any combination thereof.

9. The fluid-routing element of any one of claims 1-8, wherein the flow-field is in a form selected from a group consisting of woven wire cloth, criss-cross, expanded mesh, monoliths of porous sintered powder, and any combination thereof.

10. The fluid-routing element of any one of claims 1-9, wherein the channels have dimensions of between 0.5-3 mm in width and between 0.5-3 mm in depth.

11. The fluid-routing element of any one of claims 1-10, wherein a geometric ratio between the surface area of the forefront and the surface area of the channels is in a range of between 1 : 1-2:3, respectively.

12. The fluid-routing element of any one of claims 1-11, wherein a body thereof is made of: titanium, gold, iron, nickel, copper, aluminum, graphite, stainless steel, alloys thereof, a composite of organic-inorganic material thereof, or any combination thereof.

13. The fluid-routing element of any one of claims 1-12, wherein the electrochemical reactor is an electrolytic cell.

14. The fluid-routing element of claim 13, wherein the electrolytic cell is selected from: a proton exchange membrane water electrolyzer, an alkaline membrane water electrolyzer, and a decoupled water electrolyzer.

15. The fluid-routing element of any one of claims 1-14, wherein the reaction zone comprises a separator, a gas diffusion layer (GDL), a porous transport layer (PTL), a catalyst layer, or any combination thereof.

16. The fluid-routing element of claim 15, wherein the separator is selected from: a proton exchange membrane, an anion exchange membrane, an ion-solvating membrane, a bipolar membrane, and a diaphragm.

17. The fluid-routing element of any one of claims 1-16, is configured to conduct an electrical current to, and from, the reaction zone, and / or to remove a gaseous product from the reaction zone.

18. The fluid-routing element of claim 17, wherein the gaseous product is hydrogen and / or oxygen.

19. The fluid-routing element of any one of claims 1-18, is associated with a hydrogenevolving cathode.

20. The fluid-routing element of any one of claims 1-18, is associated with an oxygenevolving anode.

21. The fluid-routing element of any one of claims 1-20, for use as a current collector of a mono-polar or a bipolar electrode.

22. The fluid-routing element of any one of claims 2-21, wherein the flow-field channel(s) are engraved and coated with the hydrophilized polymer, and wherein the forefront of the element does not comprise the hydrophilized polymer.

23. A method for producing a fluid-routing element of any one of claims 1-22, the method comprising: obtaining a current collector comprising flow-field channels; applying a gas-repelling material layer on the current collector; and removing the applied layer from the forefront of the current collector, to obtain the fluid-routing element, such that the flow-field channels comprise the gas-repelling layer, and wherein the forefront of the element is essentially devoid of the gas-repelling layer.

24. The method of claim 23, further comprising forming a patterned channel morphology on, or in, the current collector.

25. The method of claim 24, wherein the formation of the patterned channel morphology comprises electro-deposition, electroless-deposition, (photo)lithography, sputtering, chemical vapor deposition, printing, etching, engraving, curving, or any combination thereof.

26. The method of any one of claims 23-25, wherein the current collector is surface-pretreated prior to applying the gas-repelling material layer.

27. The method of any one of claims 23-26, wherein applying the gas-repelling layer is facilitated by using a technique selected from electro-deposition, thermal deposition, chemical vapor deposition, physical vapor deposition, sputtering, spraying, layer-by- layer deposition, brushing, spin coating, pre-made film layer coating, printing, dip coating, spray coating, and any combination thereof.

28. The method of any one of claims 23-27, wherein applying the gas-repelling layer further comprises hydrophilizing the applied material and / or the surface thereof.

29. The method of any one of claims 23-28, wherein applying the gas-repelling layer comprises roughening the surface of the element by a chemical and / or physical method.

30. The method of claim 29, wherein the chemical and / or physical roughening method comprises etching, sandblasting, and / or anodizing.

31. The method of any one of claims 23-30, wherein the removal of the gas-repelling layer from the forefront of the element comprises grinding, etching, sandblasting, sanding, buffing, leaching, oxidation, scraping, polishing, or any combination thereof.

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