A dual-functional membrane for carbon dioxide capture and electrocatalytic reduction

Abstract

Disclosed herein a carbon-dioxide selective gas membrane supporting a metal-doped laser-induced graphene conductive layer. The membrane may be used for electrocatalytic reduction of carbon dioxide using gas diffusion cells.

Description

A DUAL-FUNCTIONAL MEMBRANE FOR CARBON DIOXIDE CAPTURE AND ELECTROCATALYTIC REDUCTIONFIELD OF THE INVENTION

[0001] The present invention relates to materials and processes for the capture and electrochemical conversion of carbon dioxide (CO2). More specifically, the invention concerns membranes capable of simultaneously separating CO2 from gas mixtures and catalytically reducing it to formate or other carbon-containing products under electrochemical conditions.BACKGROUND

[0002] Laser-induced graphene (LIG) is a versatile specific three-dimensional porous form of graphene (e.g., graphene foam) prepared by laser irradiation of a variety of substrates, notably polymers, polyimides and / or polysulfones, e.g., polyethersulfones, in particular. This form, including the manufacturing and various uses thereof have been disclosed, inter alia, in PCT publications of patent applications W02015175060, WO2017223217, WO2018085789, and WO2017199247; in particular, PCT patent application WO2015175060 discloses laser induced graphene (LIG) materials and their use in electronic devices; and PCT patent application WO20 18085789 discloses further methods of fabricating LIG and compositions thereof, including fabricating LIG on surfaces of various polymers, including polysulfone, polyethersulfone, and polyphenyl sulfone sheets. Using LIG in sensing applications has also been disclosed, inter alia in W02020197606, and LIG-composite adhesive has been disclosed in WO2023139588.

[0003] Electrochemical reduction of CO2 (CO2RR) to value-added products has been recognized as a sustainable route to mitigate anthropogenic emissions while producing chemical feedstocks and fuels. Numerous metallic catalysts, including silver, tin, indium, and bismuth (Bi), have been developed for the conversion of CO2 to formate (HCOO ) in aqueous media. However, all known electrocatalysts operate using high-purity CO2 feeds (> 99.9 %) under continuous gas supply. Their performance is substantially deteriorated when exposed to dilute gas mixtures such as flue gas (10-15 % CO2 in N2 or air), primarily due to limited CO2 solubility, competing O2 reduction, and poor mass transport through the liquid electrolyte.Therefore, current technologies require an upstream gas separation or capture step, typically amine scrubbing or adsorption on solid sorbents, followed by desorption and transfer of concentrated CO2 to the electrolysis reactor. This multistage approach increases system complexity and energy consumption.

[0004] Accordingly, there remains a need for materials and processes that (i) operate effectively under dilute CO2 gas feeds without pre-purifi cation, (ii) preferably, combine gas- selective separation and electrochemical functionality in a single membrane, and (iii) can be manufactured by scalable, low-cost techniques.SUMMARY OF THE INVENTION

[0005] It has now been unexpectedly found that it may be possible to conduct an efficient carbon dioxide extraction from gases having composition similar to flue gases and other sources of carbon dioxide contaminants, on an asymmetrical selective membrane with a conducting layer at the contralateral side to the side contacting the carbon dioxide source. The conducting layer is doped with a catalytic moiety, such as bismuth, and catalyzes the conversion of carbon dioxide into formate, allowing capturing and fixating carbon dioxide.

[0006] Thus, provided herein a carbon-dioxide selective gas membrane supporting a metal- doped laser-induced graphene conductive layer. Optionally, the membrane is wherein said metal is selected from the group consisting of bismuth, copper, indium, gallium, antimony, tin, and a combination thereof. Optionally, the membrane is wherein said metal is in a neutral state. Optionally, the membrane is wherein said metal is in a form nanoparticle deposited into said graphene conductive layer, or in a form of a particle integrally formed therewith. Further optionally, the membrane is, wherein said metal deposited into said graphene conductive layer is a vapor-deposited metal, an electrodeposited metal, or a reduced drop-cast metal. Optionally, the membrane is wherein said membrane comprises a polymer selected from the group consisting of a polyimide, a polysulfone, and a polyether-sulfone. Further optionally, the membrane i wherein said polymer is a polyimide, optionally wherein said polymer is a polyimide of poly-[3, 3’4, 4’ -benzophenone tetracarboxylic dianhydride and 5(6)-amino-l-(4’- aminophenyl-1, 3 -trimethylindane)]. The membrane may be comprising multiple layers of same or different composition. Optionally, the membrane is wherein at least one layer disposedon the surface of said membrane comprises a polymer amenable to graphenization with laser, and at least one layer exhibiting permselectivity to carbon dioxide over nitrogen. Further optionally, the membrane is wherein both layers comprise same polymer. Optionally, the membrane is wherein at least two of said layers comprise different polymer. The membrane may be further comprising an additional layer, optionally said additional layer being continuous or discontinuous and providing mechanical stability. Optionally, the membrane is wherein said membrane contains said metal precursor. Further optionally, the membrane is wherein said metal precursor is present contiguously to said laser-induced graphene conductive layer. Optionally, the membrane is wherein said metal precursor is selected from the group consisting of a thiol of an ion of said metal, an amine complex of an ion of said metal, or an inorganic compound comprising an ion of said metal. Further optionally, the membrane is wherein said metal precursor is a thiol. Particularly optionally, the membrane is wherein said metal precursor is selected from the group consisting of chlorobismuth ethanedithiol, tin diethanethiol, indium di ethanethiol, and bromoantimony ethanedi thiol. The membrane may optionally be wherein said metal precursor is present in said layer disposed on the surface of said membrane, and optionally is not present in any layer other than said layer disposed on the surface of said membrane. The membrane may further be comprising an additive for enhancing carbon dioxide selectivity. Optionally, the membrane is wherein said additive is titanium dioxide. Optionally, the membrane may be wherein said graphene conductive layer is present in a pattern of conductive lines separated by pristine polymer area.

[0007] In a further aspect, provided herein a process of manufacturing of a carbon-dioxide selective gas membrane supporting a metal-doped laser-induced graphene conductive layer, said process comprising providing a membrane comprising a sheet of polymer amenable to laser graphenization, and irradiating said membrane with a laser to form graphene on the surface of said sheet, wherein said sheet further comprises a precursor to said metal doping. The process may be, wherein said sheet precursor to said metal doping is selected from the group consisting of a thiol of an ion of said metal, an amine complex of an ion of said metal, or an inorganic compound comprising an ion of said metal. Optionally, the process may be wherein said metal doping precursor is selected from the group consisting of chlorobismuth ethanedithiol, tin di ethanethiol, indium di ethanethiol, and bromoantimony ethanedi thiol. Optionally, the process may be wherein said providing step comprises combining in a suitable vessel said polymer with said metal doping precursor with a solvent capable of dissolving boththe polymer and the precursor, and evaporating said solvent at an elevated temperature, said elevated temperature being between 60 and 85% of the boiling point of said solvent, to provide said membrane. The process may further be comprising curing said membrane at temperatures between 80 and 150% of the final drying temperature, for a time interval of between 2 and 24 hours. The process may optionally be, wherein said metal precursor is present in an amount of between 5% and 35% by weight of the total dry weight of said polymer and said precursor. The process may optionally be wherein said solvent is selected from the group consisting of tetrahydrofuran (THF), dichloromethane (DCM), dimethyl formamide (DMF), N-methyl- pyrrolidone (NMP), and dichlorobenzene, and mixtures of any of the above. The process may optionally be wherein said irradiating is characterized by at least one of the following: i) the power of above 1.2W and for a polyimide sheet of up to 70 pm in thickness below 2.8 W, ii) pulse density of between 600 and 1200 ppi, and iii) rastering speed of between 85 and 300 mm / s. Alternatively, the process may optionally be wherein said irradiating is characterized by at least one of the following: i) the power of above 1.2W and for a polyimide sheet of up to 70 pm in thickness below 2.8 W, ii) pulse density of between 200 and 500 ppi, and iii) rastering speed of between 85 and 300 mm / s. The process may optionally be wherein said polymer is a polyimide, said metal precursor is chlorobismuth ethanedithiol, said solvent is DMF, said metal precursor is present in said membrane in 25 %wt, said drying temperature is 110 °C, and said curing interval is 12 hours at 100 °C. Optionally, the process may be further wherein said irradiating comprises the power of between 1.2 and 2.8 W, pulse density of about 1000 ppi, and rastering speed of about 90 mm / s.

[0008] In a further aspect provided herein a process of manufacturing of a carbon-dioxide selective gas membrane supporting a metal-doped laser-induced graphene conductive layer, said process comprising providing a membrane comprising a sheet of polymer amenable to laser graphenization, and irradiating said membrane with a laser to form graphene on the surface of said sheet, wherein said metal doping is introduced by vapor deposition of said metal, electrodeposition of said metals, or drop-casting onto lased membrane.

[0009] In a further aspect, provided herein a membrane as defined herein or obtainable by a process as described herein, for use in carbon dioxide separation from gas mixtures.

[0010] In a further aspect provided herein a process of electrocatalytic reduction of carbon dioxide, comprising contacting a gaseous stream comprising carbon dioxide with a gas diffusion electrode cell, said cell comprising an anode and a gas-diffusion electrode as a cathode, in an electrolyte, said anode and cathode being separated by semipermeable ion exchange membrane, wherein said gas diffusion electrode is a membrane as defined herein, and further wherein said gaseous stream comprises less than 80% of carbon dioxide. The process may optionally be wherein said gaseous stream comprises less than 30% of carbon dioxide. Optionally, the process may be wherein said electrolyte is carbon-dioxide - saturated potassium bicarbonate in a concentration of above 1 M. Optionally, the process may be, wherein said contacting is performed between ambient pressure to the pressure corresponding to maximum transmembrane pressure of said gas-diffusion electrode membrane. The process may optionally be wherein carbon dioxide is reduced into formate ion. Alternatively, the process may be wherein carbon dioxide is reduced into a product selected from the group consisting of methane, ethylene, ethane, ethanol, methanol, propanol, formate, and acetate.BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 demonstrates a SEM cross-section image at various magnification levels, of a membrane according to the invention.

[0012] Figure 2 demonstrates Bi clusters particle size distribution as obtained from a SEM cross-section image of a membrane according to the invention.

[0013] Figure 3 demonstrates SEM plan view image of cured precursor membrane in bright contrast.

[0014] Figure 4 demonstrates electrochemical carbon dioxide reduction reaction with the membrane according to the invention as a working electrode in two configurations.

[0015] Figure 5 demonstrates linear sweep voltammograms of a membrane according to the invention used in two different configurations.

[0016] Figure 6 demonstrates linear sweep voltammograms of several systems comprising membranes, including according to the invention, at varying pressure of gaseous stream comprising carbon dioxide

[0017] Figure 7 demonstrates Faradaic efficiency and current density of various configurations of cells utilizing a membrane according to the invention.

[0018] Figure 8 demonstrates the high similarity of the performance of the membranes according to the invention in linear sweep voltammograms testing regardless of the concentration of carbon dioxide in the gaseous stream.DETAILED DESCRIPTION

[0019] Thus, in a first aspect provided herein a carbon-di oxide selective gas membrane supporting a metal-doped laser-induced graphene conductive layer. The membrane is selective for carbon dioxide and supports its diffusion through it. The membrane is usually less permeable to other gases that may be present in the gas mixture contacting the membrane, such as nitrogen, oxygen, carbon monoxide, flue gases, and the like. The membrane has a laser- induced graphene layer in direct contact with the membrane; as seen herein below, the LIG graphene layer is preferably integrally formed on the membrane by laser irradiation. The LIG is doped with metal particles, serving as catalysts. The metal particles may be applied onto LIG, or, in their turn, be integrally formed with the LIG layer. Carbon dioxide diffusing through the selective membrane reaches the LIG layer doped with the catalyst, and in presence of potential, is in-situ converted into a formate ion, or in another product, such as methane, ethylene, ethane, ethanol, methanol, propanol, or acetate, as described in greater detail herein. This selective conversion of carbon dioxide from a gaseous stream which is in contact with the selective gas separation membrane creates steep concentration gradient in the membrane, facilitating diffusion and mass transfer of carbon dioxide, increasing the permselectivity of the membrane. In fact, this is the first time when carbon dioxide electrochemical capturing was successfully demonstrated from a mixture and not from pure gas. The membrane is also interchangeably referred to herein as “eCatMem” - electrocatalytic membrane.

[0020] The terms “laser-induced graphene”, “graphene foam”, “LIG”, and like, are generally used interchangeably, unless the context clearly dictates otherwise. Generally, LIG is a singleor few-sheet of a poly crystalline carbon layer(s), e.g. less than 10 layers, with atoms arranged in multiple polygon configurations, e.g. pentagon, hexagon and heptagon structures, which is in contrast to “classic” graphene consisting exclusively of sp2-hydbidized carbon hexagons. Therefore, the terms “laser-induced graphene” and / or “LIG” encompass molecules structured into polycrystalline turbostratic carbon layers, arranged in pentagon, hexagon, and heptagon configurations, in any shape or morphology. LIG is usually obtained by laser irradiation of an amenable substrate. For example, LIG may be fabricated on Kapton™, a polyimide (PI) (e.g., poly-(4,4'-oxydiphenylene-pyromellitimide), orMatrimid 5218), or on poly(ether imides). LIG can also be manufactured on other suitable polymers as known in the art, e.g., other polyimides, polysulfones, polyethersulfones, polyphenyl sulfones, or polyamides. Preferably, the polymer wherein LIG in connection with the present disclosure is Matrimid 5218.

[0021] The polymers may preferably be provided in the form of films or sheets. Then, the polymer surface may be exposed to laser. The exposing step may be conducted with a suitable laser, e.g., with CO2 laser, e.g., disposed in a cutter system, such as for example, Universal X- 660 laser cutter platform, e.g. XLS10MWH, or a Universal Laser VLS3.50. The exposure to laser may be performed under different gases’ atmosphere, based on a gas box design, such as without being limited to, 100% air, or under hydrogen (H2), argon (Ar), nitrogen (N2), or oxygen (02) atmosphere. Preferably, the LIG is manufactured at ambient atmosphere. The laser lens may be kept clean by blowing the same gas, or air, onto it, to clear the debris and / or to cool it. The lasing parameters are readily determined for each specific substrate, as disclosed in greater detail in the background section and publications mentioned therein.

[0022] By a way of a non-limiting example, the polymer may be a polyimide, e.g., Matrimid 5218. The laser system may be a 50W 10.6 pm CO2 pulsed laser equipped with “2 inch” (50.80 mm) focal length laser lens that is characterized to produce a laser focal spot size of ca. 130 microns in diameters. LIG layer may be obtained with a process comprising laser irradiating of the substrate, with the laser power and / or energy density equivalent to obtainable with laser power setting of between 2 and 6 % (of 50 W laser), which corresponds to 1.0 and 3.0 W, preferably between 1.2 W and 2.8 W. The laser firing rate may be between 800 and 1200 pulses per inch (PPI), e.g., about 1000 ppi, and a rastering speed of between 85 and 300 mm / s, e.g., about 90 mm / s, or between 100 and 252 mm / s. It is evident that other parameters may be used as available according to the specific laser apparatus used, e.g., by adjusting the laser spotdiameter, e.g., between 100 and 160 microns, pulse density, e.g. between 600 and 1200 PPI, and the energy, provided that they correspond to a similar power or energy density and / or fluence, and the lased area. Typical laser machine parameters can include but not limited to power, speed, image density, PPI, and raster / vector modes.

[0023] The specific laser powers can vary according to the duty cycles used. For example, one can use a 50 W laser at 2% to 6% power, or duty cycle, meaning that the laser is "on" only 2% to 6% of the time, respectively. Similarly, when a 75W laser is used, the duty cycle to provide the same power of between 1 and 3W can be calculated accordingly. Thus, the duty cycle depends on the wattage of the laser used and also the fluence or the step size between the laser pulses as it traverses across the polymer (e.g. the pulses density per area, and the rastering speed), e.g. PI substrate, producing LIG, depending on the fluence.

[0024] It may be necessary to create larger graphenized surfaces. To create membranes with large surface, the rastering may be modified to apply a pattern of graphenization, creating an array of conductive carbonized lines separated by pristine polymer regions. This patterning technique allows the conductive area to be maximized while minimizing the total energy input and preventing excessive thermal damage or delamination across the full membrane. This may be achieved, e.g., by lowering the lasing density from 600-1200 ppi to generally between 20- 80% of the value, e.g., between 200 and 500 ppi, while adjusting the power output and other parameters to what as generally described herein above, e.g., with a 60W laser and power output of ca. 4.8 W (8%), to compensate for the lower ppi value. Specifically, the process may employ i) the power between 4.5 and 8 W, ii) pulse density of between 200 and 500 ppi, and iii) rastering speed of between 85 and 300 mm / s.

[0025] The metal doping in the LIG layer of the membrane is present preferably in the neutral state, e.g., as free metal. Depending on the desired final product of carbon dioxide electrocatalytic reduction, various metals may be used. The metals particularly suitable for the present disclosure may be selected from the group consisting of bismuth, copper, indium, gallium, antimony, tin, and a combination thereof. Other metals may also include silver, gold, cobalt, zinc, and palladium, and combinations of any of the above. Currently preferably, the metal includes bismuth, antimony, and tin, and Bi-Sb mixtures, when formate / formic acid conversion is intended. Additionally, molybdenum, indium, and tungsten may also be used forformate formation. In specific mixtures particularly suitable for the present disclosure in reference to formate production, bismuth is the main component, and antimony is the auxiliary component. In these binary systems the weight ratio between Bi and Sb may be between l%wt and 20 %wt, preferably between 5 and 15 %wt, e.g., 6, 7, 8, 9, 10, 11, 12, 13, or 14 %wt. most preferably about 10 %wt. Further, when hydrocarbons and alcohols are the desired products of carbon dioxide reduction, the metal may be copper, cobalt, or a mixture of copper and zinc. In some further embodiments, when carbon dioxide is catalytically reduced to carbon monoxide as a step in final fixation, the metals may be iron, silver, gold, zinc, and palladium.

[0026] The metal doping in the LIG may be present in a form of a nanoparticle. The nanoparticles may have the size of between 20 to about 150 nm, and be in any suitable shape or form. However, preferably, the nanoparticles are in form of nanoplatelets, with thickness of less than about 20 nm, and dimensions of up to 150 nm. The nanoparticles are preferably integrally formed with the LIG layer upon laser irradiation of the precursor membrane, as described below. Additionally, nanoparticles may be applied onto the LIG layer formed without doping, e.g., as drop-cast suspension of nanoparticles and drying, or chemical deposition from precursor. Additionally, the doping metals may be deposited onto and / or into LIG layer using vapor chemical deposition, or an electrodeposition process. For example, metal containing salts may be pulse electrodeposited with low overpotential, e.g., near-zero overpotential, and a total charge of between 1.8 and 2.5 C. In specific examples, bismuth nitrate at an exemplary concentration of 30 mM in 2-M solution of hydrochloric acid (with other concentrations between e.g., 10 mM to the solubility limit in given medium) may be pulse- electrodeposited with near-zero overpotential, with duty cycle varying between 50 and 100% and a total charge of about 2 C.

[0027] As mentioned above, the membrane may comprise a polymer selected from the group consisting of a polyimide, a polysulfone, and a polyether-sulfone. Currently preferably, the polymer is a polyimide available under Matrimid trademark (supplied by various suppliers, e.g., Ciba Specialty Chemicals, USA, e.g., Matrimid 5218 (fully imidized thermoplastic based on Poly [3, 3’4, 4 ’-benzophenone tetracarboxylic dianhydride and 5(6)-amino-l-(4’- aminophenyl-1, 3 -trimethylindane)]. Generally, any polyimide polymer may be suitable for the practice of the present disclosure.

[0028] The membrane may have one single layer with the LIG created on one side thereof. However, advantageously, the membrane may comprise several layers, same or preferably, different. The membrane may comprise same layers when, e.g., the desired membrane thickness is not available. However, different composition of the layers in the membrane may entail significant advantages. For example, the thickness of the membrane will not be limited to the danger of burn-through during LIG creation; one layer may be completely turned into LIG if needed, e.g., to increase the surface area, whereas other layers may still function as selective gas diffusion barrier, and / or mechanical support. As described in greater detail below, in some cases the membrane is prepared containing the doped metal precursor - a metalcontaining molecule that burns away or otherwise releases the metal during graphenization of the surface and reduces the metal ions to metallic form, creating nanoparticles embedded into LIG. These additives may change the properties of the membrane, which in some cases may be less desirable. Then, the membrane may comprise at least two layers - a first layer of pristine polymer without the doping precursor, and the second layer with the doping precursor. The thickness of the doped layer may then be significantly less than would be otherwise required by mechanical properties and the maintenance of gas diffusion barrier function. A third layer is contemplated, e.g., reinforcing mesh of inert polymer, which will allow fine-tuning of the diffusion properties of the membrane without the need to maintain mechanical force.

[0029] Thus, the membrane may comprise multiple layers of same or different composition. For example, the membrane may contain at least one layer that is disposed on the surface of the membrane, i.e., one of outermost layers, comprises a polymer amenable to graphenization with laser, and a further at least one layer exhibiting permselectivity to carbon dioxide over nitrogen. As mentioned above, the both layers (in a membrane comprising two layers) may comprise same polymer, but preferably at least two of said layers comprise different polymer. The membrane may further comprise, as discussed above, an additional layer, optionally the additional layer being continuous or discontinuous and providing mechanical stability. The continuous layer providing mechanical stability is usually moderately to highly permeable to carbon dioxide, otherwise a discontinuous layer may be used.

[0030] As mentioned above, when the metal doping is integrally formed with the LIG layer, the membrane contains a metal precursor. The metal precursor may be uniformly distributed throughout the membrane, i.e., be present in similar concentrations at either side thereof. Thus,after the formation of LIG, the metal precursor is disposed contiguously to the LIG layer. Additionally, the metal precursor may be spontaneously converted into metal particles during the manufacturing of the membrane, e.g., during the curing of the membrane. Thus-formed metal particle may be in micron and submicron range, e.g., between 500 nm and 5 pm. Further, smaller particles may be present, e.g., between about 50 nm, 75 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, and 450 nm; and 100 nm, 200 nm, 30 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1.5 pm, 2 pm, 2.5 pm, 3 pm, 3.5 pm, 4 pm, and 4.5 pm; provided that the lower limit is smaller than the upper limit for a particular range. Additionally, these metal particles may increase conductivity through the membrane, in addition to LIG.

[0031] Alternatively, the metal precursor may be applied onto the membrane, optionally with a binder, e.g., before forming LIG.

[0032] The metal precursor may be a salt or a complex of the doping metal. Preferably, the salt or complex is soluble in at least one solvent that is capable of dissolving the membrane polymer. The salts or complexes of the doping metals may be selected from the group consisting of a thiol of an ion of the metal, an amine complex of an ion of said metal, or an inorganic compound comprising an ion of said metal. Preferably, the metal precursor is a thiol. Some specific metal precursors include chlorobismuth ethanedithiol, tin di ethanethiol, indium di ethanethiol, and bromoantimony ethanedi thiol.

[0033] When the membrane comprises several layers, the metal precursor may be present only in the layer disposed on the surface of the membrane. This may advantageously allow the metal precursor to be not present in any layer other than the outermost layer, which is disposed on the surface of the membrane.

[0034] The membranes may also comprise various additives as known in the art, e.g., plasticizers, fillers, etc. Advantageously, the membrane may comprise additives that enhance carbon dioxide selectivity of the membrane. Exemplary additives include but not limited to, titanium dioxide particles.

[0035] The membranes may be manufactured by an irradiating of a suitable gas permeation selective membrane with laser to form LIG on the surface of it. The membrane may contain doping metal ion-containing precursor compound, or microparticles of doping metal. The membrane may be prepared by co-dissolving the precursor and the polymer, and casting the mutual solution onto a suitable substrate, and drying to remove the solvent. The membrane may then be cured to stabilize the membrane structure.

[0036] Therefore, in a second aspect of the present disclosure provided herein is a process of manufacturing of a carbon-dioxide selective gas membrane supporting a metal-doped laser- induced graphene conductive layer, the process comprising providing a membrane comprising a sheet of polymer amenable to laser graphenization, and irradiating the membrane with a laser to form graphene on the surface of said sheet, wherein the sheet further comprises a precursor to the metal doping. The polymers amenable to graphenization have been described herein. Preferred polymer is a polyimide. Preferably, the precursor to the metal doping is selected from the group consisting of a thiol of an ion of the metal, an amine complex of an ion of the metal, or an inorganic compound comprising an ion of the metal. Particularly preferably, the metal precursor may be selected from the group consisting of chlorobismuth ethanedithiol, tin di ethanethiol, indium di ethanethiol, and bromoantimony ethanedi thiol. These precursors have the advantage of forming a mutual solution with polyimide Matrimide 5218, in a variety of solvents, as described below, which allows easy incorporation thereof in the membrane sheet to support the metal-doped LIG.

[0037] The membrane may be provided by preparing a mutual solution of the membrane polymer and the metal doping precursor, for casting and drying into the membrane. The membrane preparation may comprises combining in a suitable vessel the polymer with the metal doping precursor with a solvent capable of dissolving both the polymer and the precursor. The dissolution of the dry materials may be effected by using a suitable mixer, e.g., and overhead mixer equipped with a suitable impeller resistant to the selected solvent. Other mixing means as known in the art may be used to effect dissolution of the starting materials.

[0038] Generally, the amount of metal doping precursor will be dependent on the metal used, the polymer, and the intended process. For example, the metal doping precursor may be presentin an amount of between 5% and 35% by weight of the total dry weight of the membrane or a membrane layer containing the precursor, i.e., the total weight of the polymer and the precursor.

[0039] The obtained solution may be degassed to remove entrapped air bubbles, e.g., by slow agitation or by applying a gentle vacuum. The solution may also be cast onto a suitable substrate for drying. Casting may be performed using film-coating techniques as known in the art, including the blade coating, slot-die coating, and others. The solution casting and drying may be performed as generally described in Membrane Technology and Applications by Richard W. Baker, 2012, ISBN 9781118359693, by Wiley publishers. The suitable substrates for casting polyimide films include but not limited to, glass or metal surfaces. The cast solution may be evaporated to produce a dried sheet. The evaporating of the solvent may usually be performed at an elevated temperature, e.g., the elevated temperature being between 60 and 85% of the boiling point of the solvent used. The evaporating may be effected by slowly ramping up the temperature at a rate of between 5 to 20 °C per hour. To control surface effects, the substrate may also be covered for controlled evaporation. This slow temperature ramping may facilitate degassing if not performed prior to the casting of the film. The final drying may also be performed at higher temperatures, e.g., between 80 and 130% of the boiling point, to effect final drying and to remove the residues of the solvent. The drying may be performed to complete dryness, as detected using a suitable loss-on-drying technique or thermogravimetric analysis.

[0040] The dried or substantially dried membrane (i.e., containing still some amounts of solvent) may be left to curing at elevated temperature for extended time intervals, to facilitate the membrane aging and stabilization. The temperatures for curing operation may be between 80 and 150% of the final drying temperature. Such, for example, when the polymer is a polyimide and the solvent is DMF, the drying and curing temperature may be about 110 °C. The dried film may be cured for 12 hours after reaching final drying temperature.

[0041] When a membrane comprises multiple layers, a further layer may be cast on top of the previous layer, and dried and / or cured likewise. When a neat gas-separation function is sought from one layer and carbon dioxide reductive conversion from the other, the neat layer may contain little or no metal precursor, maximizing the membrane permselectivity potential. Conversely, the layer that is intended to graphenization doped with metal, will usually containmetal precursors, as described generally herein, Additionally or alternatively, an amount of metal precursor solution may be applied onto dried membrane surface just prior to lasing and graphenization. The thickness of the layers may be as desired and dictated by the process requirements as generally desctibed herein. For example, the thickness of the graphenizable layer may be significantly lower in this configuration that the thickness of separation membrane. Preferably, the polymer is the same polymer in various layers, although different polymers may also be used. Alternatively, the separate layers may be cast separately, and bonded together as known in the art, e.g., by applying a mutual solvent to the surfaces of both layers, by thermal welding, ultrasonic welding, etc.

[0042] Solvents suitable for preparation of the membrane sheets may be selected by the capability to dissolve completely the required amounts of the polymer and the metal doping precursors. Preferably, the solvent may be selected from the group consisting of tetrahydrofuran (THF), dichloromethane (DCM), dimethyl formamide (DMF), N-methyl- pyrrolidone (NMP), and dichlorobenzene, and any mixture of the above. Any further solvent that is capable of dissolving the polymer and optionally the metal precursor may be suitable for the application within the embodiments of the present disclosure.

[0043] The irradiating step may be characterized by the laser system parameters. Generally, when polyimide sheets are used, the power of between 1.0 and 3.0 W, preferably above 1.2W and below 2.8 W is most appropriate, to avoid the bumthrough of the film and overoxidation on one end, and to ensure complete graphenization on the other. The pulse density of between laser firing may vary between 600 and 1200 ppi, e.g., between 800 and 1200, or between 900 and 1100 ppi, e.g., about 1000 ppi. The rastering speed may be kept between 85 and 300 mm / s, e.g., about 90 mm / s, or between 100 and 252 mm / s It is evident that other parameters may be used as available according to the specific laser apparatus used, e.g., by adjusting the laser spot diameter, e.g., between 100 and 160 microns, pulse density, etc.

[0044] In some specific embodiments, provided herein a process wherein the polymer is a polyimide, the metal doping precursor is chlorobismuth ethanedithiol, the solvent is DMF, wherein the metal doping precursor is present in the membrane in 25 %wt, the drying temperature is 110 °C, and said curing interval is 12 hours at 100 °C. In further preferredembodiments, the irradiating comprises the power of between 1.2 and 2.8 W, pulse density of about 1000 ppi, and rastering speed of about 90 mm / s.

[0045] In alternative embodiments, provided herein a process of manufacturing of a carbondioxide selective gas membrane supporting a metal -doped laser-induced graphene conductive layer, the process comprising providing a membrane comprising a sheet of polymer amenable to laser graphenization, and irradiating the membrane with a laser to form graphene on the surface of said sheet, wherein the metal doping is introduced by vapor deposition of said metal, electrodeposition of said metals, or drop-casting onto lased membrane. For example, the metal may be deposited via sputtering of metal targets, thermal or egun evaporation in vacuum chambers. The metals may be in particles form and dispersed in a solution that is then used for spray coating or drop casting.

[0046] In a further aspect provided herein a membrane, e.g., eCatMem, for use in carbon dioxide separation from gaseous mixtures. In a further aspect, provided herein a membrane obtainable by the processes as generally defined herein. The membrane obtainable by the processes may be obtained by a different process, provided that the final membrane is essentially identical to the one obtained by the processes as generally described herein. These membranes may also be used in electrocatalytic reduction of carbon dioxide.

[0047] Therefore, in a further aspect, provided herein a process of electrocatalytic reduction of carbon dioxide, the process comprising contacting a gaseous stream comprising carbon dioxide with a gas diffusion electrode cell, the cell comprising an anode, and a gas-diffusion electrode as a cathode, in an electrolyte, with the anode and cathode being separated by semipermeable ion exchange membrane, wherein the gas diffusion electrode is a membrane as generally herein or obtainable by processes as generally disclosed herein. As explained above and readily seen from the appended examples, the disclosed electrocatalytic reduction of carbon dioxide was possible for gaseous streams that comprise less than 100% of carbon dioxide, i.e., gas mixtures and not pure carbon dioxide. The gaseous stream may preferably be a flue gas. Thus, the process may utilize gaseous mixtures comprising 80% of carbon dioxide by volume, or less, e.g., 50%, 45%, 40%, 35%, 30%, 25%, 20%, 18%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, or even 3% by volume. Preferably, the gaseous stream comprises between 3% and 40% by volume, e.g., between 4 and 12% by volume, or between 10% and15% by volume, or between 12% and 35% by volume, depending on the application wherefrom flue gas is obtained. Such, the process is preferably wherein the gaseous stream comprises less than 30% of carbon dioxide.

[0048] Preferably, the contacting of the gaseous stream with the gas-diffusion electrode may be performed at any suitable pressure, between ambient and the pressure corresponding to the maximum transmembrane pressure of the gas-diffusion electrode membrane. For example, the gaseous stream pressure may be between 5 and 15 psig, or any other pressure compatible with the system and maximum transmembrane pressure of the membrane used.

[0049] The electrolyte may be any suitable solution capable of sustaining the charge transfer to run the electrochemical cell. However, preferably, the electrolyte is an aqueous solution of a salt. The electrolyte may be degassed and / or saturated with carbon dioxide prior to use. Various electrolytes may be used, but particularly preferred salt is potassium bicarbonate. The concentration of potassium bicarbonate in the electrolyte solution is preferably above 1 M, further preferably above 1.5 M. Currently preferably, the concentration of potassium bicarbonate in the electrolyte may be between 2.5 and 3.3 M at 20 °C, whereas at elevated temperatures, more concentrated solutions may be used. Additionally, the electrolyte may be circulated to remove the forming reduction products of carbon dioxide and substitute it with fresh solution.

[0050] Electrochemical carbon dioxide reduction reaction (CO2RR) may be performed on eCatMem as a working electrode in several configurations, e.g., in-solution reduction in an airtight H-cell (C007-10 Gaoss Union cell, China) with a flag counter electrode, e.g., Pt flag counting electrode (1 cm2) and a hydrogen reference electrode (mini-hydro flex Gaskatel, as described in https: / / gaskatel.com / fileadmin / Redakteur / pdf-Dateien / Bedienungsanleitungen / - Manual_TestCell_FlexCell.pdf, and currently available for purchase, e.g., from https: / / www.instrumentstrade.com / c007-10-2h-replaceable-membrane-electrolytic-cell-for- electrochemical-experiment_pl l721.html, both last accessed on 15thDecember, 2025). A further configuration may be gas diffusion electrode (GDE) testing in Flexcell test cells (Gaskatel) with a Pt spiral counter electrode (3 cm2) and a hydrogen reference electrode (minihydro flex Gaskatel). In either case, a proton exchange membrane may be used to separate the catholyte and anolyte compartments (Nafion 117).

[0051] Generally, the electrochemical reduction may be performed as known in the art, e.g., as set forth in Electrochemical Methods: Fundamentals and Applications, 3rd Edition, Allen J. Bard et al, 2022, ISBN: 978-1-119-33405-7.

[0052] Generally, the process using a polyimide eCatMem doped with bismuth at 25% by weight, may be used to transform diffused carbon dioxide into formate ion. The Faradaic efficiency of the process may be as high as above 50%, and have been demonstrated in the appended examples of up to 70%, for current densities of 10-50 mA / cm2of the membrane at absolute potential differences of between 0.7 and 1.4 V versus hydrogen reference electrode. Without being bound by a theory it is believed that even higher FE may be reached for all the reduction products, not accounted for experimentally. Therefore, the process may preferably be wherein carbon dioxide is reduced into formate ion.

[0053] Additionally, the eCatMem may be operated in continuous and uninterrupted manner for extended time intervals, e.g., between 1 h and up to several days, retaining stable current values in the GDE configuration at various potentials between -0.9V and -1.3V. Membranes may however become oxidized with prologued exposure to mixtures, e.g., containing oxidizing gases, e.g., oxygen that may be present in flue gases. The membrane oxidized by separation carbon dioxide from various air mixtures may be quickly and efficiently regenerated using any reductive bias conditions, e.g., by applying cathodic reduction in a non-oxidizing atmosphere e.g., of pure carbon dioxide, or inert atmosphere like argon or nitrogen. Carbon dioxide may be particularly advantageously used as it may be provided via the selective membrane itself.

[0054] Alternatively, carbon dioxide separable from the feed gaseous stream may also be reduced into a methane, ethylene, ethane, ethanol, methanol, propanol, or acetate, as described in greater detail above in connection with the doping metals and as generally known in the art.

[0055] As used in the specification and the claims, all scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified. All scientific and patent publications mentioned in the present disclosure are incorporated herein by reference. The definitions provided herein are to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure. The term "about", “c.a ”,and like, as used interchangeably herein, as used herein indicates values that may deviate up to 1%, more specifically 5%, more specifically 10%, more specifically 15%, and in some cases up to 20% higher or lower than the value referred to, the deviation range including integer values, and, if applicable, non-integer values as well, constituting a continuous range, preferably as used herein the term "about" refers to ± 10 %. The terms "comprises", "comprising" , "includes" , "including", "having" and their conjugates mean "including but not limited to". This term encompasses the terms "consisting of and "consisting essentially of', which have their narrower meaning as known in the art, thus an embodiment described as comprising something also discloses embodiments consisting essentially of same and consisting exclusively of same. Various embodiments and aspects of the present invention as delineated hereinabove and as claimed in the claims section below find experimental support in the following examples. The following examples are representative of techniques employed by the present Inventors in carrying out aspects of the present invention. It should be appreciated that while these techniques are exemplary of preferred embodiments for the practice of the invention, those of skill in the art, in light of the present disclosure, will recognize that numerous modifications can be made without departing from the spirit and intended scope of the invention. The singular forms “a”, “an” and “the” include plural referents unless the content clearly dictates otherwise. As used herein, a phrase in the form “A and / or B” means a selection from the group consisting of (A), (B) or (A and B), and as used herein, a phrase in the form “at least one of A, B, and C” means a selection from the group consisting of (A), (B), (C), (A and B), (A and C), (B and C) or (A, and B, and C), and further combinations are envisaged for the lists comprising larger number of terms. It is appreciated that certain features of the invention, which are, for brevity, described in the context of separate embodiments, may also be provided in combination in a single embodiment, unless technically infeasible. Conversely, combinations of various features of the invention, which are, for clarity and demonstration, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination, or as reasonable to the skilled artisan, suitable, and operative. Certain features described in the context of various embodiments, including preferred features, are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

[0056] Various other features according to the invention as described herein for the aspect of electrocatalytic membrane are applicable mutatis mutandis to the methods of manufacturingsaid membranes, or uses of said membrane, according to the teachings herein. Generally, various features according to the invention as described herein for one aspect, are applicable mutatis mutandis to other disclosed aspects according to the teachings herein. The herein described preferred embodiments provided herein demonstrating some of the embodiments of the present disclosure are provided to better understand the present disclosure, which however does not limit the invention in any respect. Some variants and equivalents may be readily envisaged by the skilled artisan; the invention therefore encompasses all these variations and equivalents.EXAMPLESExample 1 - manufacturing of eCatMem

[0057] Bismuth(III) chloride (Bids reagent grade 98 %, Sigma Aldrich, 500 mg, 1.58 mmol) was suspended in 8 mL ethanol (Romicol, 99.9 %), and stirred for 10 min under N2 at room temperature. Subsequently, 1,2-ethanedithiol (+98 %, Alfa Aesar, 149.3 mg, 1.58 mmol) was added dropwise to the white suspension, turning the mixture yellow. Stirring continued for 12 h under N2 at room temperature. The yellow precipitate was filtered, washed successively with DI water (18.2 MQ cm), ethanol, and acetone (Romicol; technical grade), and air-dried to yield Bi(III) ethanedithiol chloride (BiEDTCl) powder for use in subsequent steps.

[0058] Matrimid 5218 (fully imidized thermoplastic based on Poly [3, 3’4, 4’ -benzophenone tetracarboxylic dianhydride and 5(6)-amino-l -(4’ -aminophenyl- 1, 3 -trimethylindane)]; Ciba Specialty Chemicals, USA) and BiEDTCl complex were mixed in a 1 :3 (w / w) ratio, making up 25 wt % solids in N,N-dimethylformamide (DMF, synthesis grade; Fisher Chemical), with constant stirring for 12 h at room temperature to obtain a homogeneous black solution. The solution was then allowed to rest until all entrapped air bubbles disappeared. The bubble-free solution was blade-cast onto a clean soda-lime glass substrate (Zhuhai Kaivo Optoelectronic Technology Co., Ltd). The substrate was covered with a lid and heated gradually to 110 °C at a ramp rate of ~ 15 °C / h for controlled evaporation, and held for 12 h to complete curing. The color of the membrane gradually darkens during curing, until, after 18 h from casting, the originally yellow and translucent membrane became completely black. After cooling to ambient temperature, the Bi-Matrimid film was peeled off the substrate.

[0059] The Bi-Matrimid film surface (e.g., 50-70 gm) was converted to a graphene-rich porous layer embedded with Bi species, forming the dual -functional membrane (eCatMem), using laser pyrolysis. The process was performed using a 50 W CO2 laser (Universal VLS 3.50, = 10.6 gm). The laser power was adjusted between 1.2 W and 2.8 W, and the latter value was used, pulse density 1000 ppi, and scanning speed 91 mm / s under ambient air conditions. Laser powers < 1.2 W produced incomplete pyrolysis, while > 2.8 W caused burn-through.Example 2 - characterization of eCatMem structure

[0060] The produced membrane was evaluated with scanning electron microscopy. Crosssections were examined by SEM (Thermo Helios G4 UC, 5 kV, secondary and backscatter detectors). Uncoated samples were taped with Cu tape to minimize charging. SEM images collected at 5 kV with a secondary electron detector and backscattered detector. The STEM was collected at an acceleration voltage of 30 kV in the dark field mode with a STEM3+ detector. TEM was done with a JEOL JEM 21 OOF at an accelerating voltage of 200 kV with high angular dark field and bright field detectors. EDS was obtained from JEOL 50 mm2 Si(Li) detector.

[0061] In the lased membrane, as seen in Figure 1, the following regions could be identified: (i) a continuous polymer matrix (~ 170-200 pm), (ii) a microporous transition region (~ 50- 70 pm) with embedded irregularly shaped particles, and (iii) a surface LIG layer containing vertical grapheme whiskers decorated with further platelet-shaped particles. The particles were characterized as Bi(0). In the Figure, the white bars represent the respective distances on the picture, such as “100 gm” representing 100 micrometers, “30 gm” representing 30 micrometers, “10 gm” representing 10 micrometers, “1 gm” representing 1 micrometer, and “500 nm” representing 500 nanometers.

[0062] The SEM analysis revealed that the embedded particles have the size of 2-5 gm (average particle size was ~2.7 gm, calculated using ImageJ software), as seen in histogram presented in Figure 2. In the Figure, the total number of particles, designated as “No of particles = 205” is shown as being equal 205, with the probability (designated as “probability”) plotted along the ordinate axis, whereas the mean particle size, denoted as “Particle size (gm)”, being plotted along the abscissa axis. In parallel to the metal particle formation, curing with the added Bi precursor also leads to the formation of 2-5 pm wide voids in the membrane. Without beingbound by a particular theory, it is currently believed based on the similarity of sizes of both the metal particles and voids, that both features must have probably been present before the laser pyrolysis stage, and that the polymer on the surface shrinks during solvent evaporation, as the laser pyrolysis step usually creates significantly larger voids (>20 pm wide) below the lased surface, e.g., as seen in Figure 3, wherein SEM plan view image of cured precursor membrane (with 25%wt of Bi) is shown, with the voids’ contours and the metal particles observable in bright contrast. The white bar and the designation “10 pm” represents 10 micrometers. The LIG layer was presented as a porous grass-like layer with a high density of whiskers pointing away from the membrane, decorated with 2D plate-like structures with an apparent thickness of <20 nm. Scanning transmission electron microscopy (STEM) and EDS analysis indicated that the whiskers are also embedded with Bi-based nanoparticles of various sizes.

[0063] The membrane before LIG formation was also analyzed on a PANalytical Empyrean II X-ray diffractometer (Cu Kai, X = 1.5406 A; 40 kV, 30 mA) with an X’celerator detector, at scan rate of 3° / min. Analyzing the darkened membrane it was found that part of the Bi(III) precursor was reduced to Bi(0) during the heating-curing stage. Reflections were matched to rhombohedral Bi (R3mH, JCPDS 00-044-1246). This has been corroborated by X-Ray Photoelectron Spectroscopy (XPS), which was carried out as follows: Thermo Scientific ESCALAB 250 system, monochromatic Al Ka (1487 eV) source with 900 pm spot, 150 eV pass energy, and 1 eV step. Base pressure was 5 x 1010Torr. Calibration was done to C Is = 284.8 eV. The peak deconvolution was performed using the software package CASA XPS version 2.3. Ar+etching (2-4 keV, 10 s per cycle, 3 x 3 mm area) was used for depth profiling. Bi 4f peaks (159.0 and 164.3 eV) indicated metallic Bi° and Bi-carbonate species. Bi surface was found coated with a thin oxide layer, and the N and O signals showed minimal changes in species type and concentration with etching. Importantly, no indication of sulfur was found, suggesting that the thiols evaporated in the preparation step, possibly partly explaining the void formation.

[0064] Additionally, comparing these results with the membrane after LIG formation, it was observed that the laser pyrolysis reduced the Bi oxide to metallic Bi. Before laser pyrolysis, the Bi 4f region reveals broad (~1.7 eV) peaks centered at 164 and 159 eV. These are likely due to BiOx species. After laser pyrolysis, there were two identifiable Bi species, one of BiOx species with the peaks in the same position as before laser pyrolysis, and another pair of peaks,which are assigned to Bi(0), at 100-200 meV larger binding energies. The BiOx species are likely due to surface oxidation (based on peak areas, the BiOx / Bi(0) + BiOx = 0.05 after laser pyrolysis), while the formation of Bi(0) is in agreement with the XRD and SEM images of the platelets motif, characteristic of metallic Bi.

[0065] Additionally, the LIG layer has been analyzed with RAMAN, to verify the formation pf graphene. Raman spectra were recorded on a Horiba LabRAM HR Evolution confocal Raman microscope using a 532 nm laser, 100 pm confocal hole, 600 grooves / mm grating, and 100* objective lens. Spectrometer was calibrated with Si (520.5 cm '). Spectra were acquired from 50-3000 cm1with 30 s integration time. Distinct D (1335 cm ') peak induced by defects in sp2 carbon bonds, the first-order allowed G peak (1585and 2D bands (2670 cm ') originating from second-order zone-boundary phonons, were used as hallmark of graphenization. The obtained spectra demonstrated all three peaks characteristic of graphenecontaining materials.Example 3 - characterization of eCatMem properties

[0066] Sheet Resistance was determined using four-point probe (Keithley 6211 DC source + Keithley 2001 multimeter, probe spacing s = 1.27 mm) using equation a = ^y tk, simplified to <J = 4.532 y t, as correction factor k of thickness to probe separation ratio was approximated as ~ 1 by the setup. Bi addition to Matrimid polymer reduced sheet resistance ~9-fold vs pure Matrimid-LIG, and increasing laser power 1.2 to 2.8 W during manufacturing reduced resistance by another 10-15 %.

[0067] Gas permeability and pore sizes were measured on both dried precursor membrane and on the lased membrane. The permeability measurements for CO2 and N2 were performed by custom-made constant-volume variable-pressure permeation system, as generally described in Mizrahi Rodriguez 2022 (MR, J. Membr. Sci. 2022, 659, 120746. DOI:10.1016 / j.memsci.2022.120746), equipped with Baratron pressure transducer (range 0-10 torr, resolution 0.001 torr, MKS) at 35°C and 3-10 atma upstream pressure. The permeation system was validated by N2 permeability measurements of Polysulphone (PSf) film (25 pm, SU34- FM-000125 - Good Fellow), which was found as 0.26 ± 0.03 barrer (compared to 0.26 ± 0.04 Barrer). The selectivity was calculated as the ratio between the CO2 and N2 permeabilities. The permeability values for CO2 and N2 were also in line with known in the art, but decreased by about 2 / 3 by adding the Bi complex to form the mixed matrix membrane. The permselectivity of the membranes, however, did not change significantly, as shown in the table 1 below.Table 1

[0068] Pore size determination in the eCatMem precursor membrane and after manufacturing was performed. The membranes were cut into strips (~2 x 10 mm) and degassed at 100 °C for about 6 hours under vacuum. Nitrogen adsorption-desorption isotherms of Matrimid-only and Bi-matrix Matrimid membranes were measured using the Autosorb-IQ Gas SorptionAnalyzer (Quantachrome, Florida, USA) at the liquid nitrogen temperature, followed by the Barrett- Joyner-Hal end (BJH) method analysis using the inbuilt Autosorb software. The pore size distribution for both membrane types was in the range of 3-10 nm, with no significant differences observed in the pore size distribution between Matrimid-only and Bi-mixed Matrimid membranes.Example 4 - electrochemical performance of eCatMem

[0069] Electrochemical carbon dioxide reduction reaction (CO2RR) was tested on eCatMem as a working electrode in two distinct configurations. First configuration was in-solution testing of the membrane in an airtight H-cell (C007-10 Gaoss Union cell, China) with a Pt flag counter electrode (1 cm2) and a hydrogen reference electrode (mini-hydro flex Gaskatel, as described in https: / / gaskatel.com / fileadmin / Redakteur / pdf-Dateien / Bedienungsanleitungen / Manual- _TestCell_FlexCell.pdf, and currently available for purchase, e.g., from https: / / www.instrumentstrade.com / c007-10-2h-replaceable-membrane-electrolytic-cell-for- electrochemical-experiment_pl l721.html, both last accessed on 15thDecember, 2025). The second configuration included testing of eCatMem as gas diffusion electrode (GDE) testing in Flexcell test cells (Gaskatel) with a Pt spiral counter electrode (3 cm2) and a hydrogen reference electrode (mini-hydro flex Gaskatel). The two configurations are schematically presented in a sketch in Fig 4. Carbon dioxide molecules permeating through the membrane and being converted into formate is shown in the left pane, and carbon dioxide arriving from the solution is shown in the right pane. A proton exchange membrane separated the catholyte and anolyte compartments (Nafion 117).

[0070] As to electrolyte, 3 M potassium bicarbonate aqueous solution (Thermo Scientific 99.5 %) was used. The solution was purged with CO2 (99.999 %) at 50 seem for 30 min before use. Lower concentration (I M) resulted in potentiostat overload, therefore 3 M concentration was used to minimize solution resistance. All experiments conducted at 298 K using a singlechannel BioLogic SP-50 potentiostat. Linear sweep voltagrams (LSV) were obtained using scan rate 20 mV s ', potential rangeof 0 to -0.9V to -1.3 V vs reference hydrogen electrode (RHE). Chronoamperometry was carried out for 1 h at selected potential. Feed gases were varied between pure CO2, 10 % CO2 / 9O % N2, and 10 % CO2 / 9O % air, with back pressures varying between 0, 10, and 15 psig.

[0071] To determine Faradaic efficiency of the reaction, formate concentrations from the catholyte compartment were sampled and analyzed by 1H nuclear magnetic resonance spectroscopy (NMR, Bruker AVANCE III 500 MHz) after CO2RR. A mixture of D2O (99.9 %) and dimethyl sulfoxide (DMSO, 99.7+ %, extra dry) as internal standards was used as solvent for the samples. Unknown concentrations of formate formed were determined from a calibration curve, obtained with sodium formate standard (HCOONa 99.99 wt%) solutions for correlating the relative peak area of DMSO and formate at 2.6 and 8.3 ppm, respectively, to a known concentration. The % FE of formate was calculated using the equation%FEHCOO- =N"C°°~X 2x100,F where nucoo- is the number of moles of formate in the catholyte solution, Q is the accumulated charge that passes in the electrolysis, and F is Faraday's constant (96485 C / mol ).

[0072] The electrocatalytic activity of the eCatMem in GDE and insolution (“H-cell”) configurations is strikingly different, as shown in Fig 5. In the Figure, the membrane current density in linear sweep voltammograms, designated as “J (mA / cm2)”, is plotted along the ordinate axis, whereas the membrane potential in Volts versus a reference hydrogen electrode, designates as “Potential V. vs RHE”, is plotted along abscissa axis. Shifting from H-cell (upper curve, labelled as ’H-cell’) to GDE configuration (lower curve, labelled as ‘GDE’), the current density in the -0.9 to -1.3 V increased nearly 8 times from -l-5mA / cm2to -8-42 mA / cm2. These results indicate that carbon dioxide permeates through the membrane and reacts on the conductive electrocatalytic side of the eCatMem, whereas significantly less reacts through the solution.

[0073] Next, with doped Bi embedded into graphene layer as the electrocatalyst, the current density of >-5mA / cm2at -1 V was found against back pressure of 0 psig, as shown in Fig 6. In the Figure, the membrane current density in linear sweep voltammograms, designated as “J (mA / cm2)”, is plotted along the ordinate axis, whereas the membrane potential in Volts versus a reference hydrogen electrode, designates as “Potential V. vs RHE”, is plotted along abscissa axis. The top curve is the LSV result of a membrane without bismuth, designated “W / O Bi”, the next below is with bismuth at ambient pressure of gaseous stream, designated as “0 psig”, the following below is LSV result of a membrane with bismuth and at pressure of 10 psig, designated “10 psig”, and the lowest is the LSV result of the membrane according to theinvention at 15 psig pressure of the gaseous stream designated as “15 psig”.In contrast, without Bi as the electrocatalyst, the current density was limited to <3mA / cm2. Additionally, increasing the back pressure of 100% CO2 from 0 psig to 15 psig the current density at -1.2 V increased nearly three times from 9mA / cm2to 28mA / cm2. Such a substantial increase in current density when the carbon dioxide pressure increases further indicates that CO2 transport toward the catalyst occurs through the membrane and not into the solution towards the electrode.

[0074] The FE for formate, as shown in Fig 7, has gradually decreased in the gas permeation mode from 70% to ca. 27% when the voltage decreased from -0.9V to -1.3 V. In the figure, the left pane demonstrates the FE and current density for GDE exposed to 10% of CO2 in N2 at 15 psig, with membrane potential in Volts versus a reference hydrogen electrode, designates as “Potential V. vs RHE”, plotted along abscissa axis, and the FE and current density plotted along the left and right ordinate axes, respectively, denoted as “%FE” and “J (mA / cm2)”. The middle pane demonstrates the data for 100% CO2, and the right pane for H-cell configuration with 100% CO2. At the same time, the FE peaked at ca. 68% at -1.1 V in the “H-cell” configuration but decreased to ca.10% at -1.3 V. Thus, as seen from the figure, similar maximum FEs were found in both configurations at different potentials, but the current density was >8 times higher in the GDE configuration.

[0075] The eCatMem’s ability to separate CO2 from a CO2:N2 mixture and reduce it to formate was further demonstrated by examining the LSV under 100% CO2 and 10:90 CC>2:N2 mixture. Fig 8 shows the LSV curves of eCatMem in GDE configuration using a 100% CO2 environment and a 10% CO2 in N2 mixture at 15 psig. It can be readily seen that the LSV curves are almost identical despite different inlet gas mixture. This observation is in correspondence to similar FE for formate formations observed separately.

[0076] Additionally, the eCatMem was operated continuously for about 1 h and showed stable current in the GDE configuration at various potentials between -0.9V and -1.3V. The membranes have also been tested for 4 hours of continuous use without recording chronopotentiometry, without any observable deterioration in the performance. Membranes that oxidized in air mixtures could be quickly regenerated using carbon dioxide, rapidly restoring the typical performance.The membranes were characterized after the electrochemical reduction. XPS revealed presence of Bi 4f? / 2 = 159.3 eV (Bi-carbonate), C Is = 289.9 eV, O Is = 531-533 eV. Contact angle (measured with TBU 90E (Data Physics Ltd, Germany), 2 pL KHCCh solution droplet, static angle 123 ± 2°) reduced to 85°. SEM confirmed structural integrity of the LIG-Bi whiskers.Example 5 - manufacturing of larger eCatMem

[0077] The preparation of the membrane followed the procedure set forth in Example 1. The dried membrane was lased using pattern of carbonization with a scanning speed of 4 mm / s, a laser power set to 8%, and a pulse density of 400 pulses per inch. The resulting lased area of 16 cm2could be achieved, whereas using dense lasing at the same parameters the carbonized layer delaminated from the membrane after fabrication already after 12 cm2.Example 6- eCatMem doped with antimony

[0078] The preparation of the membrane followed as set forth in Example 1, with the following addition. Bromoantimony-ethanedithiol was added in molar ratio from 0 to 5% and 10% of that of BiEDTCl prior to casting the membrane.

[0079] The obtained membrane was characterized by SEM prior to lasing, and the size of catalytic particles appeared to be significantly reduced. Increasing concentrations of the percentage of antimony (Sb) in the electrocatalyst deposited on the electrode led to a measurable increase in the current density for CO2 reduction. The average current density, for example at -1.4V vs Ag / AgCl, increased from 3 mA / cm2(0% Sb) to 7 mA / cm2(10% Sb).

[0080] Chronopotentiometry of the hybrid membranes was performed for 30 minutes at -4.5 mA / cm2. The membranes with 10% of antimony to total catalyst reached steady state operation fastest.Example 7 - literature comparison

[0081] Versus known literature as seen below with Bi-based GDEs, the eCatMem achieved FE ~ 70 % at current densities 10-50 mA / cm2in ambient pressure operation, and functioned with dilute CO2 feeds unlike standard electrodes that require pure CO2. Multiple runs with operation times longer than 4 hours have been tested without significant deterioration.

[0082] Table 2 below describes performances of bismuth-based catalyst for CO2 to formate conversionTable 2

[0083] The references as used in the table above include:(13) Diaz-Sainz, G. et al. CO2 electroreduction to formate: Continuous single-pass operation in a filter-press reactor at high current densities using Bi gas diffusion electrodes Journal of CO2 Utilization 2019, 34, 12-19. DOI: 10.1016 / j.jcou.2019.05.035(14) Wang, Q.; Zhu, C.; Wu, C.; Yu, H. Direct synthesis of bismuth nanosheets on a gas diffusion layer as a high-performance cathode for a coupled electrochemical system capable ofelectroreduction of CO2 to formate with simultaneous degradation of organic pollutants Electrochim. Acta 2019, 319, 138-147. DOI: 10.1016 / j.electacta.2019.06.167(15) Fan, L.; Xia, C.; Zhu, P.; Lu, Y.; Wang, H. Electrochemical CO2 reduction to high- concentration pure formic acid solutions in an all-solid-state reactor. Nat Commun 2020, 11, 3633. DOI: 10.1038 / s41467-020-17403-l(16) Li, Z. et al. Fabrication of Bi / Sn bimetallic electrode for high-performance electrochemical reduction of carbon dioxide to formate Chemical Engineering Journal 2022, 428, 130901. DOI: 10.1016 / j .cej .2021.130901(17) Li, Q. et al. Novel Bi, BiSn, Bi2Sn, Bi3Sn, and Bi4Sn Catalysts for Efficient Electroreduction of CO2 to Formic Acid Industrial & Engineering Chemistry Research 2020, 59, 6806-6814. DOI: 10.1021 / acs.iecr.9b03017(18) Yang, Z. et al. MOF derived bimetallic CuBi catalysts with ultra-wide potential window for high-efficient electrochemical reduction of CO2 to formate Applied Catalysis B: Environmental 2021, 298, 120571. DOI: 10.1016 / j.apcatb.202L 120571(19) Zhao, Y. et al. Spontaneously Sn-Doped Bi / BiO Core-Shell Nanowires Toward High- Performance CO2 Electroreduction to Liquid Fuel. Nano Lett 2021, 21, 6907-6913. DOI: 10.1021 / acs.nanolett. lc02053(20) Wen, G. et al. Orbital Interactions in Bi-Sn Bimetallic Electrocatalysts for Highly Selective Electrochemical CO2 Reduction toward Formate Production Advanced Energy Materials 2018, 8, 284. DOI: 10.1002 / aenm.201802427(21) Liu, B. et al. Copper-triggered delocalization of bismuth p-orbital favours high- throughput CO2 electroreduction Applied Catalysis B: Environmental 2022, 301, 120781. DOI: 10.1016 / j . apcatb .2021.120781(22) Duan, Y.-X. et al. Boosting Production of HCOOH from CO2 Electroreduction via Bi / CeOx. Angew Chem Int Ed Engl 2021, 60, 8798-8802. DOI: 10.1002 / anie.202015713(23) Deng, P. et al. Metal-Organic Framework-Derived Carbon Nanorods Encapsulating Bismuth Oxides for Rapid and Selective CO2 Electroreduction to Formate. Angew Chem Int Ed Engl 2020, 59, 10807-10813. DOI: 10.1002 / anie.202000657(24) Xia, C. et al. Continuous production of pure liquid fuel solutions via electrocatalytic CO2 reduction using solid-electrolyte devices Nature Energy 2019, 4, 776-785. DOI: 10.1038 / s41560-019-0451-x(25) Yang, J. et al. Bi-Based Metal-Organic Framework Derived Leafy Bismuth Nanosheets for Carbon Dioxide Electroreduction Advanced Energy Materials 2020, 10, 234. DOI: 10.1002 / aenm.202001709(26) Cao, C. et al. Metal-Organic Layers Leading to Atomically Thin Bismuthene for Efficient Carbon Dioxide Electroreduction to Liquid Fuel. Angew Chem Int Ed Engl 2020, 59, 15014-15020. DOI: 10.1002 / anie.202005577(27) Garcia de Arquer, F. P. et al. 2D Metal Oxyhalide-Derived Catalysts for Efficient CO2 Electroreduction. Adv Mater 2018, 30, el802858. DOI: 10.1002 / adma.201802858(28) Gong, Q. et al. Structural defects on converted bismuth oxide nanotubes enable highly active electrocatalysis of carbon dioxide reduction. Nat Commun 2019, 10, 2807. DOI: 10.1038 / s41467-019-10819-4(29) Zhao, M. et al. Atom vacancies induced electron-rich surface of ultrathin Bi nanosheet for efficient electrochemical CO2 reduction Applied Catalysis B: Environmental 2020, 266, 118625. DOI: 10.1016 / j.apcatb.2020.118625

Claims

Claims1. A carbon-di oxide selective gas membrane supporting a metal-doped laser-induced graphene conductive layer.

2. The membrane according to claim 1, wherein said metal is selected from the group consisting of bismuth, copper, indium, gallium, antimony, tin, and a combination thereof.

3. The membrane according to any one of the preceding claims, wherein said metal is in a neutral state.

4. The membrane according to any one of the preceding claims, wherein said metal is in a form nanoparticle deposited into said graphene conductive layer, or in a form of a particle integrally formed therewith.

5. The membrane according to claim 4, wherein said metal deposited into said graphene conductive layer is a vapor-deposited metal, an electrodeposited metal, or a reduced drop-cast metal.

6. The membrane according to any one of the preceding claims, wherein said membrane comprises a polymer selected from the group consisting of a polyimide, a polysulfone, and a polyether-sulfone.

7. The membrane according to claim 6, wherein said polymer is a polyimide, optionally wherein said polymer is a polyimide of poly-[3, 3’4, 4 ’-benzophenone tetracarboxylic dianhydride and 5(6)-amino-l-(4’-aminophenyl-l, 3 -trimethylindane)].

8. The membrane according to any one of the preceding claims, comprising multiple layers of same or different composition.

9. The membrane according to claim 8, wherein at least one layer disposed on the surface of said membrane comprises a polymer amenable to graphenization with laser, and at least one layer exhibiting permselectivity to carbon dioxide over nitrogen.

10. The membrane according to claim 9, wherein both layers comprise same polymer.

11. The membrane according to claim 9, wherein at least two of said layers comprise different polymer.

12. The membrane according to any one of claims 8-11, further comprising an additional layer, optionally said additional layer being continuous or discontinuous and providing mechanical stability.

13. The membrane according to any one of the preceding claims, wherein said membrane contains said metal precursor.

14. The membrane according to claim 13, wherein said metal precursor is present contiguously to said laser-induced graphene conductive layer.

15. The membrane according to any one of claims 13 or 14, wherein said metal precursor is selected from the group consisting of a thiol of an ion of said metal, an amine complex of an ion of said metal, or an inorganic compound comprising an ion of said metal.

16. The membrane according to any one of claims 13 to 15, wherein said metal precursor is a thiol.

17. The membrane according to any one of claims 13 to 16, wherein said metal precursor is selected from the group consisting of chlorobismuth ethanedithiol, tin di ethanethiol, indium di ethanethiol, and bromoantimony ethanedithiol.

18. The membrane according to any one of claims 13 to 17, wherein said metal precursor is present in said layer disposed on the surface of said membrane, and optionally is not present in any layer other than said layer disposed on the surface of said membrane.

19. The membrane according to any one of the preceding claims, further comprising an additive for enhancing carbon dioxide selectivity.

20. The membrane according to claim 19, wherein said additive is titanium dioxide.

21. The membrane according to any one of the preceding claims, wherein said graphene conductive layer is present in a pattern of conductive lines separated by pristine polymer area.

22. A process of manufacturing of a carbon-dioxide selective gas membrane supporting a metal-doped laser-induced graphene conductive layer, said process comprising providing a membrane comprising a sheet of polymer amenable to laser graphenization, and irradiating said membrane with a laser to form graphene on the surface of said sheet, wherein said sheet further comprises a precursor to said metal doping.

23. The process according to claim 22, wherein said sheet precursor to said metal doping is selected from the group consisting of a thiol of an ion of said metal, an amine complex of an ion of said metal, or an inorganic compound comprising an ion of said metal.

24. The process according to any one of claims 22 or 23, wherein said metal doping precursor is selected from the group consisting of chlorobismuth ethanedithiol, tin di ethanethiol, indium di ethanethiol, and bromoantimony ethanedi thiol.

25. The process according to any one of claims 22 to 24, wherein said providing step comprises combining in a suitable vessel said polymer with said metal doping precursor with a solvent capable of dissolving both the polymer and the precursor, and evaporating saidsolvent at an elevated temperature, said elevated temperature being between 60 and 85% of the boiling point of said solvent, to provide said membrane.

26. The process according to claim 25, further comprising curing said membrane at temperatures between 80 and 150% of the final drying temperature, for a time interval of between 2 and 24 hours.

27. The process according to any one of claims 25 to 26, wherein said metal precursor is present in an amount of between 5% and 35% by weight of the total dry weight of said polymer and said precursor.

28. The process according to any one of claims 25 to 27, wherein said solvent is selected from the group consisting of tetrahydrofuran (THF), dichloromethane (DCM), dimethyl formamide (DMF), N-methyl-pyrrolidone (NMP), and dichlorobenzene, and mixtures of any of the above.

29. The process according to any one of claims 22-28, wherein said irradiating is characterized by at least one of the following: i) the power of above 1.2W and for a polyimide sheet of up to 70 pm in thickness below 2.8 W, ii) pulse density of between 600 and 1200 ppi, and iii) rastering speed of between 85 and 300 mm / s.

30. The process according to any one of claims 22-29, wherein said polymer is a polyimide, said metal precursor is chlorobismuth ethanedithiol, said solvent is DMF, said metal precursor is present in said membrane in 25 %wt, said drying temperature is 110 °C, and said curing interval is 12 hours at 100 °C.3 l.The process according to claim 30, further wherein said irradiating comprises the power of between 1.2 and 2.8 W, pulse density of about 1000 ppi, and rastering speed of about 90 mm / s.

32. The process according to any one of claims 22-28, wherein said irradiating is characterized by the following: i) the power between 4.5 and 8 W, ii) pulse density of between 200 and 500 ppi, and iii) rastering speed of between 85 and 300 mm / s.

33. The process according to claim 32, further wherein said irradiating comprises the power of between 4.8 W, pulse density of about 400 ppi, and rastering speed of about 90 mm / s.

34. A process of manufacturing of a carbon-dioxide selective gas membrane supporting a metal-doped laser-induced graphene conductive layer, said process comprising providing a membrane comprising a sheet of polymer amenable to laser graphenization, and irradiating said membrane with a laser to form graphene on the surface of said sheet, wherein said metaldoping is introduced by vapor deposition of said metal, electrodeposition of said metals, or drop-casting onto lased membrane.

35. A membrane as defined in any one of claims 1-21, or obtainable by a process according to claims 22-34, for use in carbon dioxide separation from gas mixtures.

36. A process of electrocatalytic reduction of carbon dioxide, comprising contacting a gaseous stream comprising carbon dioxide with a gas diffusion electrode cell, said cell comprising an anode and a gas-diffusion electrode as a cathode, in an electrolyte, said anode and cathode being separated by semipermeable ion exchange membrane, wherein said gas diffusion electrode is a membrane as defined in any one of claims 1 to 21, and further wherein said gaseous stream comprises less than 80% of carbon dioxide.

37. The process according to claim 36, wherein said gaseous stream comprises less than 30% of carbon dioxide.

38. The process according to any one of claims 36 or 37, wherein said electrolyte is carbondioxide - saturated potassium bicarbonate in a concentration of above 1 M.

39. The process according to any one of claims 36 to 38, wherein said contacting is performed between ambient pressure to the pressure corresponding to maximum transmembrane pressure of said gas-diffusion electrode membrane,40. The process according to any one of claims 36 to 39, wherein carbon dioxide is reduced into formate ion.41.The process according to any one of claims 36 to 40, wherein carbon dioxide is reduced into a product selected from the group consisting of methane, ethylene, ethane, ethanol, methanol, propanol, formate, and acetate.

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