Method for making and / or delaminating porous graphene membranes and membranes produced using the method

Abstract

Method for making a porous graphene layer (5) comprising the following steps: providing a catalytically active substrate (1) to catalyse the graphene formation under chemical vapour deposition conditions, on its surface (3) being provided with a plurality of catalytically inactive domains (2); chemical vapour deposition on the surface (3) of the catalytically active substrate (1), the pores (6) in the porous graphene layer (5) being formed in situ due to the presence of the catalytically inactive domains (2); wherein subsequent to the chemical vapor deposition the porous graphene layer (5) is removed from the substrate (3), in that the exposed porous graphene layer (5) is subjected to an aqueous solution containing a dissolved oxidant, directly or indirectly followed by treatment of the exposed porous graphene layer (5) with an aqueous persulfate solution, directly or indirectly followed by lamination of a carrier layer onto the exposed porous graphene layer (5) from the side opposite to the catalytically active substrate (1) and mechanical separation of said carrier layer (16) with the exposed porous graphene layer (5) from said catalytically active substrate (1).

Description

[0001] TITLE

[0002] METHOD FOR MAKING AND / OR DELAMINATING POROUS GRAPHENE MEMBRANES AND MEMBRANES PRODUCED USING THE METHOD

[0003] TECHNICAL FIELD

[0004] The present invention relates to a method for producing porous (‘holey’) graphene membranes that are waterproof yet highly breathable due to enhanced vapor transmission through the pores perforated within graphene layers, with a particular focus on delamination from the catalytic substrate. Furthermore, it relates to graphene membranes made using the method and uses of such membranes, as well as to catalytic substrates and uses thereof for making such membranes.

[0005] PRIOR ART

[0006] Waterproof membranes used in outdoor apparel are effective against high liquid static pressures (rain penetration resistance). However, in general they suffer from low vapor permeability to allow sufficient moisture vapor transport, breathability of the garments and user comfort.

[0007] Highly breathable membranes are also relevant to various technical textile applications including military uniforms for chemical protection, emergency responder uniforms, protective gloves and outdoor electronic circuit protective packaging. Membranes offering high efflux rates and / or selectivity also have a wide range of potential applications in separations and energy applications. They would also spark on many other potential areas of applications, unseen for the present absence of highly breathable membranes.

[0008] While GoreTex® is dominant in the waterproof membrane market, there are numerous alternative membrane providers manufacturing membranes from various polymers besides PTFE such as polyamide and polyurethanes. In each case, the membranes consist of a polymer film with small pores to enable passage of water vapor. The thickness of conventional membranes and limitations on pore area density limits the magnitude of vapor transport.

[0009] One proposed replacement material for applications where high vapor transmission and water sealing properties are required is porous graphene. Graphene, a two-dimensional, single-layer sheet of sp2 hybridized carbon atoms, has attracted world-wide attention and research interest, owing to its exceptional physical properties, including high electronic conductivity, thermal stability, and mechanical strength. The use of porous graphene membranes in fabric laminate structures has been proposed in the following documents: WO-A-2014084860 generally describes the fixation of a porous graphene layer onto a fibrous substrate backing. It describes the laminate assembly together with methods for constructing and assembling the laminate. It does not describe a method used to form the porous graphene layer.

[0010] US-A-2015273401 expands on the method described in WO-A-2014084860 with an assembly of a porous graphene membrane on a fabric substrate together with inclusion of selective membrane layers on the side of the graphene layer. The making of porous graphene membrane material is sketched to involve the growing of a contiguous monolayer and perforating the layer and a subsequent step.

[0011] Aspects relevant to porous graphene and its various production methods can be summarized as follows as categories and sub-categories.

[0012] Category 1 : Post-synthesis formation of porous graphene - Serial processes Post-synthesis formation involves perforating holes in a contiguous graphene layer, which is synthesized in a prior step. Serial processes involve hole-by-hole fabrication of the porous graphene layer. This is a slow process, which offers minimal utility for scale-up production of porous membranes.

[0013] Category 1.1 : Nitrogen assisted e-beam perforation

[0014] Scanning electron microscope (SEM) imaging in presence of nitrogen gas can be used to induce a localized reactive ion etching process by ionizing the nitrogen molecules with the focused electron beam of the SEM. With this approach, pores down to 10 nm can be etched into multilayer graphene (less than 10 layers). However, nitrogen ion diffusion out of the region of electron beam focus causes pores to etch outside of the region of interest questioning this approach to yield dense arrays of small pores. Additionally, use of the SEM makes it a serial pore milling process, which is difficult to scale up.

[0015] Category 1.2: FIB & unfocused e-beam patterning

[0016] In this two-step process, first 3keV, Ar+focused ion-beam (FIB) is used to create one- and two-atomic defects into a graphene monolayer which needs to be cooled to 148K to obtain the desired defect sizes. Next, an unfocused electron beam with 80keV is used to grow the defects from the pore fringe, while leaving the non-defected graphene parts unaffected enabling down to 0.6nm diameter pore creation.

[0017] Alternatively, focused ion beams using either Ga+or He+ions can be used to create pores from 1000nm to sub-10nm in size. The process enables control over the pore size, pore density, and pore arrangement, however due to the serial nature of the milling, scale-up remains difficult. Also, milling of sub-5nm pores is challenging.

[0018] WO-A-2015167145 discloses a graphene membrane and a method for manufacturing the same. The graphene membrane includes a graphene layer having a porous pattern including a plurality of pores having a size of 5 to 100nm and a supporter configured to support the graphene layer and including a plurality of pores having a greater size than the intended pores of the graphene layer. The proposed method involves the formation of block copolymer domains on the graphene surface to form a mask template. Subsequent exposure to ion beam irradiation is used to etch pores into the graphene layer.

[0019] Category 1.3: TEM based methods

[0020] In order to measure the translocation of DNA through graphene nanopores, free-standing graphene can be perforated by a 300kV acceleration voltage electron beam in a transmission electron microscope (TEM). Mono- and multilayer graphene can be patterned with pores ranging from 2nm - 40nm. No amorphization is observed in the vicinity around the pore, indicating that the local crystallinity is preserved. This method is however not parallel and takes quite some time.

[0021] Category 2: Post-synthesis formation of porous graphene - Parallel processes Post-synthesis formation involves perforating holes in a contiguous graphene layer, which is synthesized in a prior step. Parallel processing involves perforating the graphene layer in multiple locations at the same time.

[0022] Category 2.1 : Ultraviolet-induced oxidative etching

[0023] UV-etches are performed to create sub-nm defects into graphene, which grow upon prolonged exposure. Repeating 15 etches with 1 min exposure to a bilayer graphene membrane e.g. yield pores that show size selective sieving of SFe, which has a kinetic diameter of 4.9A.

[0024] Category 2.2: Ion bombardment & oxidative etching

[0025] Ga+ ions with 8keV can be accelerated at the graphene surface with 52° angle of incidence creating defects into the graphene lattice. Subsequently, the graphene defects can be etched using acidic potassium permanganate to etch unsaturated carbon bonds and thus enlarge the pore until a stabilization at 0.4nm pore diameter after 60min etch time occurs, which is thought to originate from formation of functional groups inhibiting a further growth reaction.

[0026] Category 2.3: Oxygen plasma

[0027] Sub-nm pores can be created by exposing suspended monolayer graphene to 1s - 6s of oxygen plasma etch (20W), where the etch time determines the pore size and density. Pore sizes of 0.5 - 1nm at a pore density of 1pore / 100nm2can be achieved with 1.5s exposure to the plasma.

[0028] Category 2.4: Strain-assisted Pt nanoparticle perforation

[0029] Self-assembly of block copolymer (BCP) micelles containing Pt precursor leads to distributed Pt nanoparticles across a substrate onto which a previously prepared graphene monolayer can be transferred such that perforation is obtained after annealing at 400°C. Catalytic perforation of graphene is facilitated due to localized strain at the Pt nanoparticles. The pore size and density can be controlled with the micelle composition leading down to 17nm pores at 12.8% porosity. Large-scale perforation in theory should be possible, however obtaining a uniform dispersion of Pt precursors is challenging and the largest areas shown are ca. 4pm2.

[0030] Category 2.5: Perforation using catalytic oxidation in contact with metal particles

[0031] KR-A-20120081935 and KR-A-101325575 propose to apply a thin metal film layer (Au or Ag) deposited onto surface of an existing graphene layer followed by an annealing step to form metal particle domains on the graphene surface. Further thermal steps lead to formation of pores at the contact to the metal domains via a catalytic oxidation.

[0032] Category 2.6: Using anodic alumina as template

[0033] Graphene on a substrate can be patterned using an anodic alumina membrane. The anodic alumina is placed with the small pore side facing the existing contiguous graphene substrate and a plasma exposure removes the graphene if not protected by the alumina. The resulting pore size is 40nm - 60nm.

[0034] Category 3: Formation of porous graphene membranes from graphene platelets

[0035] Porous membranes of graphitic layers may alternatively be formed through the assembly of films composed of graphene (or graphene oxide) platelets. The platelets in principle form a laminar structure with pores forming between the platelet boundaries. The graphene platelet approach tends to form relatively thick layers that do not fully exploit the inherent two-dimensional planar (low thickness) geometry of graphene.

[0036] Category 3.1 : Pore template during film formation

[0037] CN-A-104261403 describes a preparation method for graphene film with a three- dimensional porous structure. Polystyrene domains are used as a sacrificial template for pore formation within a film layer formed from graphene oxide platelets as starting material. Category 4: Direct synthesis of porous graphene membranes

[0038] Direct synthesis of porous graphene membranes involves the simultaneous formation of graphene layer(s) that directly form porous features in the graphene layer. Direct synthesis methods avoid the need for post-synthesis processing to achieve the porous structure.

[0039] Category 4.1 : Pores due to grain boundary defects

[0040] EP-A-2511002 proposes the growth of a graphene layer on an untreated copper substrate. The monolayer is subsequently solution coated with PMMA and then immersed in an etchant to remove the copper. The PMMA-layer carrying the graphene layer was attached to a PTMSP film and the PMMA layer removed using a solvent. In the resultant graphene layer a plurality of grains of graphene is present with pores as defects between the graphene grains. The patent describes the membrane properties for separation of various substances from liquids and gases. Category 4.2: Template patterning of carbon source followed by graphene layer formation CN-A-103241728 provides a method for preparing a graphene nanopore array, which comprises the following steps: 1) coating a carbon source solution on the surface of a porous anodic alumina (PAA) template; 2) pressing the PAA template with the carbon source coated on the surface of a metal base, peeling the PAA template, and ensuring that the carbon source is preserved on the surface of the metal base and the carbon source preserves a pattern which is consistent with that on the surface of the PAA template; and 3) performing annealing treatment on the obtained metal base in the presence of a mixed gas flow of hydrogen gas and argon gas, thus converting the carbon source into the graphene nanopore array. The nanopore array obtained by the invention is an interconnected nanopore array structure rather than a single nanopore or several nanopores; and the pore size of the nanopores can be regulated through the template effect of the PAA itself, and can be further regulated through growing and etching in the later stage.

[0041] TW-A-201439359 describes a method for forming a large-area graphene layer on a porous substrate by a chemical vapor deposition process. In a first step, carbon material is deposited onto a porous template using CVD. In a second step, the carbon material undergoes annealing and catalytic graphitization to convert the carbon to a graphene layer. In a third step, liquid exfoliation is used to reduce the number of graphene layers on the substrate.

[0042] Category 4.3: Direct growth of porous graphene using porous templates and patterns CN-A-102583337 describes a preparation method for graphene material with porous structure. Porous magnesium oxide / silicon composite material is used as a template substrate. Chemical Vapor Deposition (CVD) is used to grow graphene directly on the porous template. The graphene layer retains the porous structure of the template substrate. The porous graphene layer is recovered by destructive etching of the magnesium oxide / silicon composite substrate.

[0043] US-A-2012241069 discloses how a graphene pattern is fabricated by forming a pattern of passivation material on a growth substrate. The pattern of passivation material defines an inverse pattern of exposed surface on the growth substrate. A carbon-containing gas is supplied to the inverse pattern of the exposed surface of the growth substrate, and patterned graphene is formed from the carbon. The passivation material does not facilitate graphene growth, while the inverse pattern of exposed surface of the growth substrate facilitates graphene growth.

[0044] US-A-2013160701 proposes methods for growing microstructured and nanostructured graphene by growing the microstructured and nanostructured graphene from the bottom-up directly in the desired pattern. The graphene structures can be grown via chemical vapor deposition (CVD) on substrates that are partially covered by a patterned graphene growth barrier which guides the growth of the graphene.

[0045] WO2017212039 proposes a method for making a porous graphene layer of a thickness of less than 100 nm with pores having an average size in the range of 5-900 nm, comprising the following steps: providing a catalytically active copper substrate catalyzing graphene formation under chemical vapor deposition conditions, said catalytically active substrate in or on its surface being provided with a plurality of catalytically inactive domains having a size essentially corresponding to the size of the pores in the resultant porous graphene layer; chemical vapor deposition using a carbon source in the gas phase and formation of the porous graphene layer on the surface of the catalytically active substrate, the pores in the graphene layer in situ being formed due to the presence of the catalytically inactive domains.

[0046] In the field of graphene CVD growth Dong et al (The Growth of Graphene on Ni-Cu Alloy Thin Films at a Low Temperature and Its Carbon Diffusion Mechanism, Nanomaterials (Basel). 2019 Nov; 9(11): 1633) found that carbon solid solubility in metals is an important factor affecting uniform graphene growth by chemical vapor deposition (CVD) at high temperatures. At low temperatures, however, it was found that the carbon diffusion rate (CDR) on the metal catalyst surface has a greater impact on the number and uniformity of graphene layers compared with that of the carbon solid solubility. The CDR decreases rapidly with decreasing temperatures, resulting in inhomogeneous and multilayer graphene. In the work, a Ni-Cu alloy sacrificial layer was used as the catalyst based on the following properties. Cu was selected to increase the CDR, while Ni was used to provide high catalytic activity. By plasma-enhanced CVD, graphene was grown on the surface of Ni-Cu alloy under low pressure using methane as the carbon source. The optimal composition of the Ni-Cu alloy, 1 :2, i.e. a Ni proportion of 33%, was selected through experiments. In addition, the plasma power was optimized to improve the graphene quality. On the basis of the parameter optimization, together with our previously-reported, in-situ, sacrificial metal-layer etching technique, relatively homogeneous wafer-size patterned graphene was obtained directly on a 2-inch SiO2 / Si substrate at a low temperature (-600 °C).

[0047] Losurdo et al (GrapheneCVD growth on copper and nickel: role of hydrogen in kinetics and structure, Phys. Chem. Chem. Phys., 2011 ,13, 20836-20843) report, that understanding the chemical vapor deposition (CVD) kinetics of graphene growth is important for advancing graphene processing and achieving better control of graphene thickness and properties. In the perspective of improving large area graphene quality, they have investigated in realtime the CVD kinetics using CH4-H2 precursors on both polycrystalline copper and nickel only substrates. They highlighted the role of hydrogen in differentiating the growth kinetics and thickness of graphene on copper and nickel. Specifically, the growth kinetics and mechanism is framed in the competitive dissociative chemisorption of H2 and dehydrogenating chemisorption of CH4, and in the competition of the in-diffusion of carbon and hydrogen, being hydrogen in-diffusion faster in copper than nickel, while carbon diffusion is faster in nickel than copper. It is shown that hydrogen acts as an inhibitor for the CH4 dehydrogenation on copper, contributing to suppress deposition onto the copper substrate, and degrades quality of graphene. Additionally, the evidence of the role of hydrogen in forming C-H out of plane defects in CVD graphene on Cu is also provided. Conversely, resurfacing recombination of hydrogen aids CH4 decomposition in the case of Ni. Understanding better and providing other elements to the kinetics of graphene growth is helpful to define the optimal CH4 / H2 ratio, which ultimately can contribute to improve graphene layer thickness uniformity even on polycrystalline substrates.

[0048] Samir Al-Hilfi (Chemical vapour deposition of graphene on Cu-Ni alloy, Thesis, The University of Manchester, 2018) has explored the impact of C solubility in the catalytic substrates, on the CVD growth of graphene. Cu-Ni alloys show complete solid solubility across their composition range and can be used to explore the influence of C solubility on graphene growth. Graphene is grown on Cu-Ni alloys of composition Cu, Cu70-Ni30, Cu55- Ni45, Cu33-Ni67 and Ni in a hot-wall CVD reactor. So, in all cases either the substrate was Ni free or contained at least 30% Ni. Firstly, the growth was achieved on pure metals (Cu and Ni) using CH4 as a C source and the produced film was characterised by Raman spectroscopy and scanning electron microscopy (SEM). The C profile within the substrate bulk was measured by glow discharge optical emission stereoscopy (GDOES). The latter showed the difference in bulk C content between Cu and Ni, which reflects the influence on the graphitic film on the surface. The CVD growth of graphene on Cu-Ni alloy showed a transition from bilayer graphene (BLG) to few layer graphene (FLG) surface coverage when the Ni content increased, which is accompanied by an increase in the diffusion of C in the bulk and incubation time. The cooling rate showed a significant effect on the graphene surface coverage; however, the influence varied with Ni content. The fluid flow simulation indicated that the gas velocity beneath the substrate is very low which results in a lower mass transfer to the bottom substrate surface. Gas-phase kinetics simulation reveals the impact of gas residence time on the concentration of active species; moreover, the concentration increases down the stream of the flowing gas. Finally, the surface reactions of the CH4 / H2 mixture model showed a good agreement with the experimental observations under low growth pressure; however, it failed at high growth pressure.

[0049] WO2021121952 discloses a method for making a porous graphene layer of a thickness of less than 100 nm, comprising the following steps: providing a catalytically active substrate, said catalytically active substrate on its surface being provided with a plurality of catalytically inactive domains having a size essentially corresponding to the size of the pores in the resultant porous graphene layer; chemical vapour deposition and formation of the porous graphene layer on the surface of the catalytically active substrate; wherein the catalytically active substrate is a copper-nickel alloy substrate with a copper content in the range of 98 to less than 99.96 % by weight and a nickel content in the range of more than 0.04-2 % by weight, the copper and nickel contents complementing to 100% by weight of the catalytically active substrate.

[0050] US4784687 reports that the scarcity of high-grade tungsten ores obliges users to seek to recover it from scrap materials, but drill bits in particular pose especial problems. Existing proposals to use acidic hydrogen peroxide to oxides and solubilize tungsten is extremely inefficient in reagent consumption per unit tungsten recovered. According to the present invention, hydrogen peroxide can be used considerably more efficiently in the extraction of tungsten into an aqueous acidic solution by employing certain promoters which are solid at 50 DEG C. in the form of fused blocks. These blocks release the promoter slowly into the reaction solution and achieve similar efficiency of use of hydrogen peroxide and acid but at markedly reduced consumption of promoter in comparison with the same promoter added in powder or granular form. Examples of such promoter are hydroxy or amino substituted aromatic carboxylic acids e.g. 2-hydroxybenzoic acid. The promoters can most conveniently be used in a multi-stage tungsten extraction process.

[0051] In summary, the existing technology for the waterproof breathable membranes can be improved and there exists room for improvement and needs for breakthrough technology to gain vapor breathability (rapid gas phase transport) while maintaining the liquid barrier properties, for the sake of customer comfort and protection of materials beneath the garment or packaging. Porous graphene membranes have been proposed for such applications, and also have been analyzed and compared with conventional breathable membranes and have been shown to exhibit better breathability, but the existing processes for making suitable porous graphene membranes are not always sufficiently suitable for upscaling and industrial processes.

[0052] SUMMARY OF THE INVENTION

[0053] One crucial aspect in relation with these processes for the manufacturing of porous graphene layers is how to delaminate them from the catalytic substrate on which the graphene layers are grown.

[0054] Current state-of-the-art graphene delamination processes include etching methods, electrochemical delamination, and mechanical delamination.

[0055] Etching methods, involving removal of the catalytic substrate through complete dissolution, are rather established, however they are time-consuming, costly, complicated and generate a lot of chemical waste, the recovery of which is requiring energy and cost.

[0056] Electrochemical delamination is nondestructive and allows to reuse the catalytic substrate. However again electrolyte and electricity are required, and in particular the generated bubbles required to effectively separate the graphene from the catalytic substrate, may cause defects in the porous graphene layers deteriorating the properties thereof, and the process is slow if bubbles are to be avoided as much as possible. For highly porous graphene this method is therefore not suitable.

[0057] Mechanical delamination is nondestructive and allows to reuse the substrate, and in principle allows for short delamination time. On the other hand, to allow for mechanical delamination along pretreatment for the oxidation of the catalytic substrate layer is required, so the method is using up the substrate layer. In addition, there are strong adhesive forces between the graphene and the catalytic layer, so the control of this mechanical delamination is difficult and for highly porous graphene this method is therefore also not suitable.

[0058] The above-mentioned document WO-A-2021 / 121952 discloses a delamination method involving a pre-leaching process with sodium hydroxide solution at elevated temperatures, followed by PMMA coating as temporary carrier substrate layer and baking at elevated temperature, followed by electrochemical delamination or by mechanical delamination. Also disclosed is a method for characterization in which, after pre-leaching and PMMA coating, the catalyst substrate is fully dissolved away by floating in an ammonium persulfate solution, transfer to a silicon wafer, and subsequent PMMA layer removal by acetone. This method however only allows for characterization but not for subsequent transfer to a porous woven or nonwoven carrier material for a final use. The problem with sodium hydroxide preleaching in any case is that it does not allow to fully remove the tungsten (or other non- catalytic) nanoparticles on the catalytic substrate. The document discloses immersion of as grown graphene on the substrate into an NaOH solution. It is well known that NaOH is a reducing agent and under the conditions given in this document will reduce the WO3 of the catalytically inactive domains into Na2WO4.

[0059] According to a first aspect of the invention it relates to a method for making a porous graphene layer of a thickness of less than 100 nm with pores having an average characteristic width as defined in the specification in the range of 1 - 1000 nm, comprising the following steps: providing a catalytically active substrate to catalyse the graphene formation under chemical vapour deposition conditions, said catalytically active substrate on its surface being provided with a plurality of catalytically inactive domains having a nanostructure essentially corresponding to the shape of the pores in the resultant porous graphene layer; chemical vapour deposition using a carbon source in the gas phase and formation of the porous graphene layer on the surface of the catalytically active substrate, the pores in the porous graphene layer being formed in situ due to the presence of the catalytically inactive domains.

[0060] So far, the process is based on the procedure as disclosed in the above-mentioned documents WO-A-2017 / 212039 and WO-A-2021 / 121952, the content of which as concerns these above steps is expressly included into this disclosure.

[0061] The proposed method includes the following elements:

[0062] 1. The preparation of a (preferably specific copper / nickel alloy) catalytic substrate;

[0063] 2. The preparation of a topology of catalytically inactive material on top of such a catalytic substrate in the form of catalytically inactive nanostructures;

[0064] 3. The synthesis of a porous graphene layer on a (copper / nickel alloy) catalytic substrate with such a topology of catalytically inactive nano material, which is then followed by

[0065] 4. Pre-leaching conditioning of the porous graphene layer interface with the catalytic substrate, and

[0066] 5. Mechanical separation of the porous graphene layer from the catalytic substrate; optionally:

[0067] 6. Applying such a porous graphene layer on a nonwoven or porous fabric.

[0068] These individual steps can be carried out as follows:

[0069] 1. Preparation of Cu-Ni alloy:

[0070] Cu catalyst e.g. as purchased from Alfa Aesar (Copper foil, 0.025 mm, 99.8%, Product No. 49686) is provided; a Ni film with a varied thickness from 10 nm to 2.2 pm or 50 to 300 nm is deposited on as-received commercial Cu catalyst by E-beam evaporator or sputtering in vacuum (e.g. FHR, Pentaco 100, Ni purity 99.95%, 3 x 10-3 mbar); pressure of the sputtering is about 0.006 mbar with 200 seem of Ar; the resulting film of Ni is deposited from 10 nm to 2.2 pm or 50 to 300 nm with DC plasma whose power is 0.25 kW; a bi-layered structure of Ni / Cu catalyst is annealed at e.g. 1000 °C for e.g. 1 hour to convert to a binary metal alloy (Cu-Ni alloy) under low pressure (e.g. 200 mTorr) with e.g. 50 seem of H2 in a chemical vapor deposition (CVD) system (e.g. Graphene Square. Inc, TCVD-RF100CA).

[0071] The concentration of Ni is more than 0.04% to 10% or preferably in the range of more than 0.04 to 2% by weight, or also in the range of 0.1 - 10% preferably in the range of 0.2-8% or 0.3-5%, typically in the range of 0.4-3%. Particularly preferably, the catalytically active substrate has a nickel content in the range of 0.06 - 1% by weight or 0.08 - 0.8% by weight complemented to 100% by weight by the copper content. The balance is Cu (for the broadest range it is thus 99.96 - 90%, for a typical range it is 99.94 less than 99% or 99.6- 97%, the balance does not include very minor impurities which can be present in the starting Cu foil or in the starting Ni, and which in the final substrate make up less than 0.05% or less than 0.02% by weight in total). The range of Ni content depends on the initial Ni thickness. The typical working content of Ni is preferably in the range of 0.5-2%.

[0072] 2. Conversion of W thin film into W nanostructures:

[0073] A thin film of W (thickness 1-10 nm) can be deposited on the Cu-Ni alloy according to the preceding paragraph by sputtering or E-beam evaporator in vacuum (e.g. FHR, Pentaco 100, W purity 99.95%) with e.g. E-beam evaporator or sputtering in vacuum (e.g. 3 x 10-3 mbar); the pressure of the sputtering is e.g. 0.002 mbar with e.g. 100 seem of Ar; the thin film of W is deposited from 1 to 10 nm with e.g. 0.25 kW of DC plasma; a W / Cu-Ni alloy is mounted in the center of a 4-inch quartz tube chamber positioned in the furnace of the CVD system (e.g. Graphene Square. Inc, TCVD-RF100CA); the chamber is evacuated to reach a pressure of e.g. 45 mTorr and then purged with inert gas, e.g. N2 (e.g. 100 seem) for e.g. 5 min normally at room temperature; after purging, the chamber is put under vacuum (e.g. 45 mTorr) again and then the pressure is increased e.g. with a gas mixture of Ar and H2 (800 seem and 40 seem, respectively); to convert the W thin film into W nanostructures (NSs). The NSs are based variously on symmetric W nanoparticles and asymmetric W nanowalls with various degrees of interparticle agglomeration. The W / Cu-Ni alloy is carefully annealed at elevated temperature (e.g. 750-950°C or 800-900°C) for an extended period of time, e.g. 1 hour including ramping with the continuous supply of e.g. 800 seem of Ar and 40 seem of H2 under 4 Torr.

[0074] 3. Synthesis of highly porous graphene

[0075] Once W nanostructures appear in the process according to the preceding paragraph, e.g. a hydrocarbon source for example 40 seem of methane is introduced in the chamber with e.g. 300 seem of Ar and 40 seem of H2 under 4 Torr in the low-pressure CVD system; depending on the desired level of porosity or thickness, a growth duration is carefully controlled from e.g. 5 to 120 min or 5 - 60 min; afterwards, the furnace is programmed to cool to room temperature under flow of Ar and H2. Under these conditions, a total CVD time of 30 to 120 minutes leads to a graphene layer thickness of approximately 10 nm. CVD time of 5 minutes leads to a graphene layer thickness of approximately below 1 nm, but this may also depend on further parameters.

[0076] 4. Pre-leaching conditioning of highly porous graphene:

[0077] After the growth of highly porous graphene, directly or after an intermediate treatment, a pre-leaching process with oxidant for as-grown highly porous graphene on its exposed surface is carried out as detailed below. The sample material can subsequently be rinsed with Dl-water and dried prior to the next step. This is followed by subjecting the highly porous graphene on its exposed surface to persulfate treatment as detailed below. The sample material can subsequently be rinsed with Dl-water and dried prior to the next step. This is followed by application of a carrier layer on the exposed surface of the highly porous graphene.

[0078] 5. Mechanical separation of highly porous graphene with carrier layer as detailed further below.

[0079] Recycling of the catalytic substrate:

[0080] After the process of mechanical separation (delamination), the Cu-Ni alloy can be re-used to grow highly porous graphene, repeatably.

[0081] 6. Polyurethane non-woven interface (which can be the above-mentioned carrier layer or an addition layer added after the process, can also be another thermoplastic polymer in non-woven or otherwise porous woven or knitted structures):

[0082] 1. Normally characteristic filament diameter: 314 nm (standard deviation: 190 nm) (the characteristic filament diameter is defined as a diameter of the individual filament of the non-woven material on average)

[0083] 2. Normally characteristic pore width: 1281 nm (standard deviation: 603 nm) (the characteristic pore width is defined as a width of the individual topmost pore in the nonwoven material on average).

[0084] More generally speaking, the present invention according to a first aspect thereof relates to a method for making a porous graphene layer of a thickness of less than 100 nm, in particular with pores having an average characteristic width in the range of 1-1000 nm, preferably in the range of 5 - 900 nm, comprising the following steps: providing a catalytically active substrate to catalyse the graphene formation under chemical vapour deposition conditions, said catalytically active substrate on its surface being provided with a plurality of catalytically inactive domains having a nanostructure essentially corresponding to the shape of the pores in the resultant porous graphene layer; chemical vapour deposition using a carbon source in the gas phase and formation of the porous graphene layer on the surface of the catalytically active substrate, the pores in the porous graphene layer being formed in situ due to the presence of the catalytically inactive domains.

[0085] The average characteristic width of the pores is defined and measured as follows:

[0086] As the shape of pore becomes elongated and uneven, resulting from the W nanostructures, it is challenging to obtain the pore diameter. The characteristic width was, therefore, chosen and defined as the widest width of pore rather than the diameter of the pore. The characteristic width of the pores was extracted by using image analysis software (Imaged) on scanning electron microscope (SEM) images. Porous graphene was transferred onto SiNx chip including hole with 4 pm in diameter to make a free-standing section suitable for clear image interpretation. Five representative SEM images of porous graphene were then, taken over 1.14 pm2to visualize the clear difference in the contrast between pore and surrounding graphene (e.g., black for pore and grey for graphene). As the characteristic width of pore is few tens of nm, high magnification SEM images were required. Afterward, based on the SEM image, the widest width of each pore opening was measured and the average of the measured widths subsequently calculated.

[0087] According to a preferred embodiment of the invention, in particular the catalytically active substrate is a copper-nickel alloy substrate with a copper content in the range of 85-98 % by weight or 90 - 99.9 by weight and a nickel content in the range of 2-15 % by weight or in particular more than 0.04-2 % by weight, the copper and nickel contents complementing to 100% by weight of the catalytically active substrate.

[0088] Using such a catalytically active substrate alloy it is possible to make relatively thick graphene layers having also higher porosity than the previously available porous graphene layers. Without being bound to any theoretical explanation, it appears that this particular alloy allows the provision of particular topologies of catalytically inactive domains on the surface thereof and as a result of this topological structure allows the making of thicker graphene layers with superior gaseous permeation and liquid barrier properties.

[0089] The porous graphene layer preferably has a thickness in the range of less than 50 nm, preferably in the range of 1-20 nm, in particular in the range of 5-15 nm or 7-12 nm.

[0090] For the preferred nickel concentration, the corresponding graphene preferably has an areal porosity (defined as the ratio of total area of pores to total projected area of the layer) of more than 2.5%, preferably of more than 5%, preferably in the range of 10-70%, and at the same time a thickness in the range of more than 1 nm, preferably of more than 2 nm, preferably in the range of 2-15 nm. Further preferably the porous graphene layer has an areal porosity, defined as the areal fraction of pore space in the total graphene layer, in the range of at least 10%, preferably at least 15%, more preferably of at least 20% or at least 25%, or at least 40%.

[0091] According to yet another preferred embodiment, the catalytically active substrate is provided on its surface with a plurality of catalytically inactive domains by applying, preferably using sputtering, e-beam evaporation or PVD, an essentially contiguous tungsten layer. Preferably this tungsten layer has a thickness in the range of more than 1 nm, preferably more than 3 nm, more preferably more than 5 nm, or in the range of 1-10 nm, preferably in the range of 5-10 nm. Subsequently this structure is subjected to a step of annealing at a pressure below normal pressure, preferably of less than 100 mTorr or less than 4 Torr, in particular under a reducing atmosphere, preferably in the presence of an inert gas such as argon or nitrogen gas, combined with hydrogen gas, to convert the tungsten film into a plurality of catalytically inactive domains. Typically, the annealing takes place at a temperature in the range of 700-1100°C, more preferably in the range of 750-950°C or 800- 900°C, typically during a time span in the range of 10-180 minutes, preferably in the range of 10-60 min or 50-100 minutes.

[0092] According to a preferred embodiment the method is adapted such as to obtain catalytically inactive domains having an average characteristic width in the range between 1-1000 nm, preferably in the range of 10 - 100 nm, more preferably in the range of 10-50 nm, or preferably having an average characteristic width in the range between 5-900 nm, preferably in the range of 10-200 nm, more preferably in the range of 10-100 nm.

[0093] The step of chemical vapour deposition to form the graphene layer can be carried out using a carbon source in the gas phase under formation of the porous graphene layer on the surface of the catalytically active substrate, the pores in the graphene layer in situ being formed due to the presence of the catalytically inactive domains, using methane gas as carbon source, preferably in the co-presence of argon and hydrogen gas under reduced pressure, preferably below 50 Torr, preferably below 5 Torr, during a time span of preferably in the range of 10-120 minutes, preferably below 60 minutes, more preferably below 50 minutes, most preferably below 35 minutes. This graphene layer deposition process preferably takes place during a time span allowing for the generation of a graphene layer of average thickness of more than 5 nm, preferably in the range of 8-12 nm.

[0094] The porous graphene layer can be removed from the catalytic substrate, and can furthermore be applied to a porous, preferably nonwoven or fabric supporting substrate, preferably in that for removal of the graphene layer first a supporting carrier layer is applied to the graphene layer on the surface opposite to the catalytic substrate and the sandwich of this carrier layer and graphene is removed from the catalytic substrate, and then this structure can be directly or indirectly applied to the porous, preferably nonwoven or fabric supporting substrate, followed by removal of the temporary carrier layer if needed.

[0095] As the carrier layer before mechanical separation from the substrate preferably a porous material layer is chosen. This type of carrier layer can be classified into two categories: track-etched membrane and non-woven porous membrane. Track-etched membranes exhibit porosity that refers to the percentage of the total surface area occupied by the pores (as characterized through electron microscopy imaging), typically ranging from less than 1% to 16%. In case of non-woven porous membrane, porosity represents the percentage of the total volume occupied by the pores, which typically falls between 40% to 80%.

[0096] The carrier layer can be a woven or nonwoven layer, and it can be based on at least one of the following materials: bio-based materials or synthetic materials or a combination thereof, the former including cotton, rayon, cellulose, chitosan, alginate, starch, keratin, fibroin, or a combination thereof, the latter including polyurethane (Pll; e.g. Finetex ENE), polyester, polycarbonate, polyamide, polyacrylonitrile, polyethersulfone, polyethylene, polypropylene, polysiloxanes, poly methyl methacrylate, or a combination thereof.

[0097] The porous material layer can be added to the exposed surface of the highly porous graphene layer by lamination.

[0098] The graphene layer after or for mechanical separation from the catalytic substrate can be attached to a porous, preferably nonwoven or fabric supporting substrate, preferably having a characteristic filament diameter in the range of 200-2000 nm, preferably in the range of 300-1000 nm, in particular with a standard deviation in the range of less than 500 nm, and / or having a characteristic pore size in the range of 500-50000 nm, preferably in the range of 1000-10000 nm, in particular with a standard deviation in the range of less than 1000 nm.

[0099] Preferably the nonwoven or fabric supporting substrate is attached to the graphene layer using solvent induced bonding or heat bonding, wherein preferably adhesion to non-woven is effected using isopropanol-mediated adhesion plus annealing and / or heat treatment.

[0100] According to the invention, in particular and more broadly speaking, subsequent to the chemical vapor deposition of the porous graphene layer the porous graphene layer is removed from the substrate, in that the exposed porous graphene layer on the surface of the catalytically active substrate is subjected to an aqueous solution containing a dissolved oxidant (leading in particular to an oxidation of the catalytically inactive domains, in case of iron oxidant solutions such as Murakami's reagent containing potassium ferricyanide, this leads to the formation of FeW04), directly or indirectly followed by treatment of the exposed porous graphene layer on the surface of the catalytically active substrate with an aqueous persulfate solution (Chemical reaction: S2O82" + Cu = Cu2++ 2SO42"), directly or indirectly followed by lamination and / or generation of a carrier layer onto the exposed porous graphene layer from the side opposite to the catalytically active substrate and mechanical separation of said carrier layer with the exposed porous graphene layer from said catalytically active substrate.

[0101] It is noted that for the catalytically inactive domains (in particular W nanoparticles) to be dissolved, an oxidation of the catalytically inactive domains (in particular W nanoparticles) has to precede their dissolution. When 0.1 M NaOH at a mild temperature (40-60°C) is used, an oxidation reaction of W nanoparticles e.g. due to the oxygen gas contained in the water is slow. As a result, it takes too long to remove W nanoparticles, and even if, W nanoparticles are not completely removed, there are always leftover within realistic reaction times. With an extended period, not only do some W nanoparticles remain on the metal catalyst surface, NaOH is also crystalized on the graphene surface. Therefore, the slow kinetics of 0.1 M NaOH alone makes it essentially unuseable.

[0102] The aqueous solution containing a dissolved oxidant therefore preferably comprises a dissolved, preferably iron based, oxidant and sodium hydroxide and / or potassium hydroxide. The oxidant dissolved according to this invention does not include gas such as oxygen gas which is present in a solution, this is not considered a "dissolved oxidant" for not being dissolved.

[0103] So according to the invention, a process is proposed without complete chemical dissolution of the substrate.

[0104] Important elements of this process are the new pre-leaching process (removal of W nanoparticles) and water intercalation separation (highly porous graphene delamination). The binding energy between graphene and metal plays a key role in graphene separation (delamination).

[0105] In the process, the W thin film is converted into W nanoparticles, and subsequently WC (tungsten carbide) nanoparticles upon an introduction of carbon feedstock. Carbon atoms at the edge of pores in highly porous graphene bind to WC nanoparticles, and W-C and C- C binding energy are high. Therefore, with electrochemical and mechanical delamination it is not possible to detach highly porous graphene from the metal catalyst. To overcome this, the proposed method provides for a suitable and adapted pre-leaching step with oxidant followed by a step of gentle breaking (conditioning) of the adhesion between the catalytic substrate and the highly porous graphene layer without complete chemical dissolution of the substrate.

[0106] The proposal is a pre-leaching process comprising a dissolved oxidant, e.g. Murakami’s reagent, for the removal of WC nanoparticles, and a persulfate (e.g. APS, ammonium persulfate) treatment, in particular for partial etching at the Cu-Ni alloy to graphene interface surface, wherein, without being bound to any explanation, the APS solvent penetrates through the pores of the exposed surface of the porous graphene layer which allows fast and spatially uniform lateral diffusion and subsequent localized etching throughout the interface, followed by application of a carrier layer and (water intercalation) separation, wherein e.g. water penetrates into the interface between hydrophobic graphene and hydrophilic Cu-Ni surface due to capillary force. So, the highly porous graphene can be easily separated from the catalytic surface.

[0107] The proposed process is not only more reliable and stable, economically and ecologically beneficial, it also allows for a massive reduction in production time, at least by a factor of 2 or 3 compared with a pre-leaching and electrochemical delamination processes.

[0108] According to a preferred embodiment of the proposed method, before treatment with a persulfate solution, the catalytically active substrate with the porous graphene layer is rinsed with water, preferably with distilled water, more preferably repeatedly rinsed with distilled water.

[0109] According to another preferred embodiment of the proposed method, the aqueous solution containing a dissolved oxidant is selected from the group consisting of: an aqueous hydroxide solution comprising ferricyanide, or an acidic solution comprising hydrogen peroxide (e.g. HNO3 + H2O2 or H2SO4 (3% w / w) + H2O2 (9% w / w)).

[0110] Preferably the aqueous solution containing a dissolved oxidant is selected from an aqueous sodium hydroxide and / or potassium hydroxide solution comprising further sodium ferricyanide and / or potassium ferricyanide, such as Murakami's reagent. The reaction taking place normally is then: oxidation of tungsten carbide by (potassium) ferricyanide; chemical reaction between WO3 and (Na)OH to form Na2WC>4 (sodium tungstate) and water; sodium tungstate is water soluble and a recycling source of tungsten for subsequent chemical synthesis.

[0111] Preferably in such a aqueous solution containing a dissolved oxidant the weight proportion of potassium (and / or sodium) hydroxide is in the range of 0.05-10%, preferably in the range of 0.1-3% or in the range of 0.3-2% or in the range of 0.5-1.5%, and / or the weight proportion of potassium (and / or sodium) ferricyanide to water is in the range of 0.05-10%, preferably in the range of 0.1-3% or in the range of 0.3-2% or in the range of 0.5-1.5%, in each case relative to 100% of water used for the preparation of that solution.

[0112] Preferably for the aqueous solution containing a dissolved oxidant a diluted version of a starting reagent having been prepared by adding 10 g of potassium ferricyanide and 10 g of potassium hydroxide to 100 mL of water is used, such that the starting solution has a potassium ferricyanide concentration of 0.3M and a potassium hydroxide concentration of 1.8 M. Preferably the dilution with water is by at least 80%, or by at least 90% or by up to 95%, so the concentration is reduced to 1 / 5, to 1 / 10 or 1 / 20, respectively, from that starting concentration.

[0113] Preferably, the aqueous solution containing a dissolved oxidant is an aqueous solution comprising, preferably exclusively, potassium (and / or sodium) hydroxide and potassium (and / or sodium) ferricyanide, and wherein the concentration of (potassium) hydroxide is in the range of 0.05-0.4M, preferably in the range of 0.07-0.2M, and wherein the concentration of (potassium) ferricyanide is in the range of 0.005-0.1 M, preferably in the range of 0.01- 0.04M. Or the ratio of the weight proportion of sodium hydroxide to the weight proportion of potassium ferricyanide is in the range of 0.2-5, preferably in the range of 0.5-2 or in the range of 0.8-1.2.

[0114] According to another preferred embodiment of the proposed method, the step of treatment with the aqueous solution containing a dissolved oxidant is carried out at a temperature in the range of 15-35°C, preferably in the range of 20-30°C, and / or over a time span in the range of 0.5-20 minutes, preferably in the range of 1-5 minutes.

[0115] Preferably, said aqueous persulfate solution comprises persulfate selected from the group consisting of: ammonium persulfate, sodium persulfate, potassium persulfate, or a combination thereof, wherein preferably the persulfate concentration is in the range of 0.05- 2M, preferably in the range of 0.075-1.5M.

[0116] The step of treatment with the aqueous persulfate solution is normally carried out at a temperature in the range of 15-35°C, preferably in the range of 20-30°C, and / or over a short time, so e.g. a time span in the range of 1-180 seconds, preferably in the range of 5-120 or 5-60 or 5-20 seconds.

[0117] According to another preferred embodiment of the proposed method, directly following the step of treatment with the aqueous persulfate solution, the substrate with the porous graphene layer is rinsed with water, preferably with distilled water, more preferably repeatedly rinsed with distilled water.

[0118] According to another preferred embodiment of the proposed method, mechanical separation of said carrier layer with the exposed porous graphene layer from said substrate is carried out by water intercalation separation, preferably by gradual immersion into water, preferably distilled water. Mechanical separation in the present context means that the mechanical separation action is not done by surmounting the interfacial adhesion force, but rather the adhesion is released through the pre-leaching and the separation is mediated by the water intercalation and (gentle) separation in contrast to mechanical delamination methods.

[0119] Said carrier layer is preferably a porous carrier layer, preferably the carrier layer intended for final use e.g. in clothing or the like as defined further below.

[0120] According to another preferred embodiment of the proposed method, the catalytically active substrate is a copper-nickel alloy substrate with a copper content in the range of 98 to less than 99.96 % by weight and a nickel content in the range of more than 0.04 to 2% by weight, the copper and nickel contents complementing to 100% by weight of the catalytically active substrate (1), wherein preferably the catalytically active substrate has a nickel content in the range of 0.06 - 1 % by weight or 0.08 - 0.8% by weight complemented to 100% by weight by the copper content. Further the invention relates to a graphene layer, preferably on at least one carrier layer, obtainable or obtained using a method as given above.

[0121] Such a layer may have a thickness in the range of less than 50 nm, preferably in the range of 1-20 nm, in particular in the range of 5-15 nm or 7-12 nm and / or it may have an areal porosity in the range of at least 10%, preferably at least 15%, more preferably of at least 20% or at least 25% or at least 30% or at least 40%.

[0122] Further the invention relates to a piece of textile or apparel having at least one graphene layer, preferably on at least one carrier layer, made using a method defined above and / or as defined above, preferably in the form of a water resistant and / or water repellent and / or breathable apparel.

[0123] Last but not least the invention relates to a use of a graphene layer, preferably on at least one carrier layer, made using a method defined above or according to above as a semipermeable membrane, in particular for textile applications in the field of apparel, or in the technical field, in particular for providing water barrier in electronics and / or mobile devices.

[0124] Further embodiments of the invention are laid down in the dependent claims.

[0125] BRIEF DESCRIPTION OF THE DRAWINGS

[0126] Preferred embodiments of the invention are described in the following with reference to the drawings, which are for the purpose of illustrating the present preferred embodiments of the invention and not for the purpose of limiting the same. In the drawings,

[0127] Fig. 1 shows a schematic representation of the first phase of the process including the growth procedure of porous graphene and pre-leaching process by Murakami’s reagent;

[0128] Fig. 2 shows representative SEM images of the surface of the metal catalyst (a) with graphene layer before and (b) after the pre-leaching process by Murakami’s reagent for 2 minutes;

[0129] Fig. 3 shows representative SEM images of the surface of the metal catalyst with graphene layer after the pre-leaching process by Murakami’s reagent for different degrees of dilution of Murakami’s reagent and depending on the dilution of Murakami’s reagent, (a) no dilution, (b) 80% dilution, (c) 90% dilution, and (d) 95% dilution;

[0130] Fig. 4 shows a schematic representation of the second phase of the process including the APS treatment and water separation;

[0131] Fig. 5 shows representative SEM images of the surface of the metal catalyst (a) after the pre-leaching process by Murakami’s reagent without graphene layer and (b) after pre-leaching process by Murakami’s reagent and APS treatment without graphene layer;

[0132] Fig. 6 shows representative (a) AFM image of porous graphene on SiO2 and (b) SEM image of porous graphene on the porous polymer membrane;

[0133] Fig. 6 shows the presence of tungsten particles after sodium hydroxide only treatment during 5 minutes (a), 10 minutes (b) and 15 minutes (c);

[0134] Fig. 7 shows the formation of sodium hydroxide crystals after sodium hydroxide only treatment of 15 minutes (a), 20 minutes (b) and 30 minutes (c);

[0135] Fig. 8 shows the effects of treatment with Murakami's reagent during 10 seconds (a), 20 seconds (b) and 30 seconds (c).

[0136] DESCRIPTION OF PREFERRED EMBODIMENTS

[0137] Fig. 1 schematically illustrates the first phase of the proposed method in the individual steps up to and including the preleaching. A catalytic copper / nickel substrate is in a first step on the surface provided with a layer 12 of catalytically inactive material, in particular a layer 12 of tungsten in a tungsten deposition step 11. Subsequently this coated substrate 1 is optionally introduced into an enclosure and is then subjected to a step of thermal annealing 15 under reducing conditions. The result is the generation of the pattern of catalytically inactive domains 2 on the surface 3 of the catalytic substrate 1. In the following step 4 of growth of the graphene layer on the substrate 1 again in the optional enclosure the substrate 1 is subjected to chemical vapour deposition of methane leading to the formation of the porous graphene layer 5, interrupted by the catalytically inactive domains 2 locally forming the holes for the future porosity. In a following step of removal of the enclosure (if used at all), this layered substrate is freed.

[0138] Then this layered substrate is subjected to a pre-leaching step by immersion into Murakami's reagent to remove the catalytically inactive domains 2. The conditions are as follows: 10g KOH + 10g K3[Fe(CN)6] + 100 ml Water for 2 min.

[0139] Then this layered substrate is subjected to rinsing in DI water (8, DI water as mentioned herein is water that has been treated to remove all ions, typically, that means all of the dissolved mineral salts, it normally has a conductivity of less than 10 pS / cm or less than 1 or 0.5 pS / cm; also distilled water can be used which has been boiled so that it evaporates and then re-condensed, leaving most impurities behind) for 2 min.

[0140] Fig. 2 shows representative SEM images of the resulting structures, i.e. of the surface of the metal catalyst 1 (a) with graphene layer 5 before and (b) after the pre-leaching process by Murakami’s reagent for 2 minutes. As one can see from the comparison of these pictures, the bright spots in the illustration of the un-pre-leached representation (Fig. 2a), which show the catalytically inactive domains 2, i.e. the tungsten dots, on the surface of the catalytic substrate 1 , are completely removed after the pre-leaching (Fig. 2b). This was also confirmed by elemental analysis of the separated graphene layer and by inspection of the surface of the catalytic substrate 1 after removal of the highly porous graphene layer as will be detailed further below.

[0141] This is a major advantage compared with previously known pre-leaching processes, because in the previously known pre-leaching processes without oxidative component under many conditions there were residuals of the tungsten which remained in / on the highly porous graphene layer, which on the one hand was problematic in terms of re-coverage of the tungsten in a cyclic process and in terms of undesired tungsten content in the final graphene layer.

[0142] Fig. 3 shows representative SEM images of the metal catalyst with graphene layer after the pre-leaching process by Murakami’s reagent for different degrees of dilution of Murakami’s reagent and depending on the dilution of Murakami’s reagent, (a) no dilution, (b) 80% dilution, (c) 90% dilution, and (d) 95% dilution (see also more detailed experimental information further below).

[0143] The effectiveness of various dilutions of Murakami’s reagent in eliminating tungsten carbide particles from the surface of the catalytic substrate with varied time. This is because undiluted Murakami’s reagent succeeds in completely removing tungsten within 10 seconds while causing partial graphene layer detachment during Dl-water rinsing. Consequently, it is not always optimal for graphene membrane applications. To address this issue and prevent any potential damage, the utilization of diluted Murakami’s reagent is advisable. Three dilution percentages, namely 80%, 90%, and 95%, were tested. The 80% dilution of Murakami’s reagent required 30 seconds to remove tungsten without causing any damage. The 90% diluted Murakami’s reagent effectively eliminated tungsten from the substrate surface without any damage within 60 seconds. Similarly, the 95% dilution of Murakami’s reagent successfully etched all tungsten on the surface of the catalytic substrate within 120 seconds, with no observable damages. Consequently, the reaction time can be precisely controlled to align with the post process if necessary.

[0144] Fig. 4 schematically illustrates the following, second phase of the proposed method in the individual steps up to and including the preleaching. The structure resulting from the process as illustrated in Fig. 1 in this second phase is subjected to a persulfate treatment, i.e. a step of immersion into an aqueous persulfate solution 9. The corresponding conditions are as follows: 0.1 M ammonium persulfate solution ((NH4)2S20s in water, APS) for 10 sec. This APS treatment under conditions where there is an exposed surface of the porous graphene layer 5 for a short time span allows for a slight edging of the interface between the porous graphene layer 5 and the catalytic substrate 1 , leading to a released bond 13 between these two layers, as the surface 3 of the layer 1 is accessible for the APS solution through the pores 6 in the layer 5. However, the conditions are adapted such that the substrate layer 1 is not completely edged away.

[0145] Subsequent to this edging step with APS, the catalytic substrate 1 with the porous graphene layer 5 on its surface 3 is subjected to rinsing with DI water. The conditions are as follows: 60 secs in Dl-water.

[0146] This leads to a structure where the porous graphene layer 5 is located on the catalytic substrate 1 (illustration in the top row of Fig. 4 to the very right), but where the previously rather strong bond between the catalytic substrate 1 and they graphene layer 5 is released 13, so the structure is prepared for gentle mechanical removal of the porous graphene layer 5 from the substrate 1. This is initiated by first applying a porous membrane or carrier layer 16 to the exposed surface of the porous graphene layer 5 in a step 14 of application of a carrier layer. This can be a step of lamination, but it can also be a step of in situ formation of the porous membrane layer 16 on the porous graphene layer 5.

[0147] Once this sandwich structure 21 of the porous membrane layer 16 and the porous graphene layer 5 is generated, the structure is ready for removal of that sandwich structure 21 from the catalytic substrate 1. This is for example possible by gradual immersion of the structure 1 , 21 into a bath of an aqueous solution or Dl-water 17. The final structure 21 will then gradually float in a free-floating part 19 on the surface 18 of the water and will gradually be released from the substrate 1 , so the still on substrate part 20 will become smaller and smaller. After that process the supported released porous graphene layer 21 , which is floating in a controlled way on the surface 18 of the water, can be picked up without any harm to the structure 21 , in particular by using its upper surface.

[0148] Fig. 5 shows representative SEM images of the surface of the metal catalyst (a) after preleaching process by Murakami without graphene layer and (b) after pre-leaching process by Murakami and APS treatment without graphene layer. As one can see from the illustration, after the pre-leaching process by Murakami, there is essentially no tungsten on the catalytic copper / nickel substrate. Hence, the pre-leaching step ensures the efficient and complete removal of tungsten. However, the catalytic substrate’s roughness becomes pronounced due to NaOH’s oxidation during the pre-leaching process, necessitating additional treatment to achieve a smooth surface. Conversely, the APS treatment, which follows the pre-leaching process, loosens the bond between the graphene layer and the surface of the catalytic substrate and mildly etches the interfacial surface, resulting in a smooth surface. Therefore, APS treatment proves advantageous for the recycling of the catalytic substrate, promoting its reusability.

[0149] Fig. 6 shows representative (a) AFM image of porous graphene on SiO2 and (b) SEM image of porous graphene on the porous polymer membrane. The samples were prepared according to the process in Fig. 1 and 4. For example, a preparation method involves the synthesis of porous graphene, which is then subjected to the pre-leaching process by Murakami, followed by APS treatment. This treatment prepares the porous graphene layer for separation, with or without a porous membrane. Following the separation process, the porous graphene without porous membrane is transferred onto SiO2 and the porous graphene with porous membrane is directly picked up. Notably, as depicted in Fig. 6 (a) and (b), the structural integrity of the porous graphene remains intact even after undergoing the pre-leaching process and subsequent APS treatment. This observation highlights the fact that these processes do not adversely affect the structural characteristics of the porous graphene.

[0150] Detailed working examples:

[0151] Making of Cu / Ni substrate:

[0152] A Cu-Ni alloy catalyst was formed for synthesizing thick highly porous graphene. As- received Cu foil without any treatment (0.025 mm, 99.8%, Product No. 49686, Alfa Aesar) was coated a film of Ni by physical vapor deposition (PVD, sputtering or e-beam evaporation). Ni film (50-500 nm in thickness or 0.01 - 2.2 pm in thickness) was coated by using sputtering (FHR, Pentaco 100, Ni purity 99.95%) under 6x10-3mbar with 200 seem of Ar and 0.25 kW of plasma power for 85 - 18700 sec or 425 to 4250 sec, depending upon the thickness of Ni film. The bi-layered Ni / Cu was placed in low-pressure chemical vapor deposition (LP-CVD, Graphene Square. Inc, TCVD-RF100CA) system to anneal. Temperature of a furnace was first ramped up to 1000 °C for 60 min with 50 seem of H2. Further, the annealing process was performed at 1000 °C for 15 min in H2 environment to prevent unwanted oxidation. Afterward, a formation of Cu-Ni alloy was completed by interdiffusing in bulk state, resulting from being completely soluble in the other. In order to rapidly decrease the temperature down to room temperature, the furnace was moved to downstream position. A cooling rate of 50 °C / min resulted while maintaining the same level of H2. Making of W nanostructures on Cu / Ni substrate:

[0153] After the formation of the Cu-Ni alloy, a thin film of W (2-10 nm) was deposited on the Cu- Ni alloy by using sputtering (FHR, Pentaco 100, W purity 99.95%). The deposition was carried out with 0.25 kW of DC power and 100 seem of Ar under 3x1 O'3mbar for 15 to 75 sec, leading to a varied thickness.

[0154] As-prepared W / Cu-Ni alloy was placed in the middle of furnace in the LP-CVD system. The chamber was pumped out until 0.05 mTorr by turbo molecular pump to remove any residual gases and then the pressure was increased up to 45 mTorr with 50 seem of Ar. Afterward, the chamber was purged out with N2 for 5 min and vacuumed down to 45 mT orr. The furnace was heated up to the growth temperature of 750-950 °C or 800-950 °C with the supply of 800 seem of Ar and 40 seem of H2 under 4 Torr. Once the target temperature was reached, the temperature was maintained for 10 min to stabilize. In the meantime, the thin film of W was transforming into W nanostructures due to solid-state de-wetting. Since there is no solid solubility between Cu-Ni alloy and W, different morphologies of W nanostructures can be obtained without any pre-lithography processes.

[0155] Making of graphene layer:

[0156] When the desired morphology of W was achieved, the synthesis of highly porous graphene was then carried out with the introduction of 40 seem of CH4, 40 seem of H2, and 300 seem of Ar under 4 Torr for 30 min. Then, the temperature was programmed to cool down to room temperature under a mixture of 800 seem of Ar and 40 seem of H2. The resulting structure is given in Fig. 2a (see also further above).

[0157] Pre-leaching step:

[0158] After the CVD synthesis of highly porous graphene, a pre-leaching process was carried out to remove the W nanostructures in a state where the highly porous graphene is exposed, i.e. is freely accessible from the side opposite to the catalytic substrate. As-synthesized highly porous graphene on the catalytic substrate was immersed in Murakami's reagent, i.e. 10g KOH + 10g Ka[Fe(CN)6] + 100 ml Water for 10 to 120 sec as a function of the concentration of the reagent (see also further below) at room temperature (temperature of 20 °C, 293.15 K, and an absolute pressure of 1 atm, 101.325 kPa, this standard is also called normal temperature and pressure, abbreviated as NTP). The highly porous graphene / Cu-Ni alloy sample was then immersed in fresh Dl-water twice for 60 secs each to rinse and subsequently dried by flushing with N2 gas. The resulting structure is given in Fig. 2b (see also further above).

[0159] A series of different dilution degrees and immersion times was run from the same starting material to investigate the behaviour of pre-leaching, namely no dilution with immersion for 10 secs, 80% dilution with immersion for 30 secs, 90% dilution with immersion for 60 secs, and 95% dilution with immersion for 120 secs. The resulting structure is given in Fig. 3 (see also further above).

[0160] Graphene layer release:

[0161] To release the bond between the Cu-Ni alloy catalyst substrate and the highly porous graphene, the Cu-Ni alloy catalyst substrate with the highly porous graphene layer was immersed in a 0.1 M ammonium persulfate solution ((NH4)2S20s, APS, 248614, Sigma Aldrich) for 10 seconds at room temperature (NTP). The resulting structure was then rinsed with Dl-water for 60 seconds.

[0162] Applying and assembly of highly porous graphene onto porous non-woven material:

[0163] An assembly of highly porous graphene with porous non-woven material such as polyurethane (Finetext ENE, DT007) was carried out. After the pre-leaching process, the non-woven material was adhered onto the highly porous graphene in various ways: (1) Isopropanol (IPA)-mediated adhesion and (2) heated lamination.

[0164] The assembly of highly porous graphene with porous non-woven material (i.e., approximately 1 .2 pm of characteristic hole diameter and 9 pm in thickness) was achieved in the IPA-mediated method and / or heated lamination. The IPA-mediated adhesion process involves the direct lamination of a thin non-woven material onto pre-leached highly porous graphene at room temperature. The lamination is followed by gentle application of IPA until complete wetting is achieved. Subsequently, the laminated sample is left to dry under ambient conditions. During the drying process, as the IPA evaporates, the interfacial contact between the non-woven material and the highly porous graphene is significantly enhanced, thereby ensuring a robust adhesion. To further reinforce the bond, the dried sample is subjected to heating on a hotplate (I KA, C-Mag HS 7) at 150 °C for 10 minutes. For the heated lamination method, the thin non-woven material was directly laminated on preleached highly porous graphene with a varied temperature depending on the glass temperature of polymer. Alternatively, the heated lamination method is employed, wherein the thin non-woven material is directly laminated onto pre-leached highly porous graphene at a temperature tailored to the glass temperature of the polymer. In the case of the polyurethane membrane, the polyurethane carrier layer is directly laminated onto preleached highly porous graphene at 130 °C. Following the lamination process, the sample is heated on the hotplate (I KA, C-Mag HS 7) at 150 °C for 10 minutes to further improve the adhesion. Alternative approaches to working with non-woven materials include direct deposition of fibers onto the porous graphene substrate for example via electrospinning or melt spinning of fibers.

[0165] Graphene layer separation:

[0166] To lift-off the highly porous graphene with the carrier layer from the Cu-Ni alloy catalyst substrate, the Cu-Ni alloy catalyst substrate with the highly porous graphene on the carrier layer was, under an angle relative to the water surface and the highly porous graphene on the carrier layer facing upwards, gradually immersed into Dl-water so that the highly porous graphene on the carrier layer gradually floats on the surface of the water under liff-off from the Cu-Ni alloy catalyst substrate. The resulting structure is given in Fig. 6b (see also further above).

[0167] For analysis purposes the sample was transferred on a Si wafer having 280-nm-thick SiC>2 to investigate the highly porous graphene. See Fig. 6a (see also further above).

[0168] Membrane preparation for measurement of gas flow rate and water entry pressure:

[0169] The assembly of highly porous graphene with the non-woven material was cut into small piece of around 1 cm x 1 cm. A frame of 2 cm x 2 cm for the assembled membrane was made of stainless steel with a hole of 2 mm at the center of the frame. The assembled membrane was laid on the metal foil including a small hole of 0.8 mm in diameter as a mechanical support. Afterward, the whole membrane was attached in carbon tape punched a hole in the middle on either side of the membrane and then sandwiched by the frame. Note that every hole needs to be aligned axially.

[0170] Gas flow rate measurement:

[0171] The nitrogen gas permeance flow rate was characterized using a custom-built setup. The membrane described above was placed in a custom-made fixture and the sealing was achieved by utilizing rubber O-rings on both sides of the membrane. Nitrogen was issued to the feed side and pressure controlled by a regulator (SMC, IR1000-F01) with measurement of the pressure rise upstream by digital manometer (OMEGA, HHP91). A mass flow meter (MKS, Germany) measures the flow rate in seem at the downstream. All the measurements were carried out at room temperature.

[0172] The assembly of highly porous graphene onto the non-woven material was fabricated by following the synthesis of highly porous graphene and the assembly of them described above. The highly porous graphene was synthesized on the catalyst where Ni film of 150 nm was deposited on top of commercial Cu foil by sputtering process and subsequently bi- layered Ni / Cu catalyst was annealed to transform into Cu-Ni alloy. The synthesis process of highly porous graphene having approximately 24% of porosity and 5-nm thick on the Cu- Ni alloy with thin film of W of 4 nm was carried out at 800 °C with the introduction of 40 seem of CH4, 40 seem of H2, and 300 seem of Ar under 4 Torr for 30 min. In addition, the duration of the synthesis was adjusted from 30 to 60 min, leading to a decrease in porosity for the purpose of investigating how porosity of graphene affects gas flow rate. After the assembly of highly porous graphene with the non-woven material in the IPA-mediated method was performed, the metal catalyst was etched away by 0.5 M APS and was rinsed with the mixture of 5% ethanol and Dl-water, following the dry process.

[0173] The membrane of highly porous graphene / non-woven material was mounted on the stainless-steel frame. The frame with the membrane was placed and clamped in the custom-made fixture which was connected to the gas line with the regulator and to the mass flow meter. Note that the mass flow meter is limited by 20 seem of N2. The pressure of N2 was slowly and gradually increased. For example, the pressure of N2 was increased in a step of 20 mbar and maintained for 1 min to stabilize the pressure until the mass flow meter showed 20 seem of N2.

[0174] To illustrate in particular the difference between a treatment of a catalytic substrate (with tungsten particles as catalytically inactive particles) and having a graphene layer formed thereon as disclosed in WO2021121952, using sodium hydroxide under the conditions there, the following experiments were carried out.

[0175] As mentioned, for W nanoparticles to be dissolved, an oxidation of W nanoparticles has to precede their dissolution.

[0176] When 0.1 M NaOH at a mild temperature (40-60°C) is used, an oxidation reaction of W nanoparticles is very slow. As a result, it takes more than 10 minutes to remove W nanoparticles.

[0177] Even then, W nanoparticles are not completely removed, there are always some leftovers within optimal reaction time.

[0178] Fig. 7 illustrates the results of corresponding experiments. Using a procedure according to WO2021121952, i.e. 0.1 M NaOH at 40 °C, at 5, 10 and 15' as illustrated in a), b) and c) respectively, the circles indicate where remaining W nanoparticles remain. For a 5-min-long reaction (a), most of W nanoparticles remained on the surface, hindering a mechanical separation. For 10-min-long reaction (b), lots of W nanoparticles are still observed on the surface. For 15-min-long reaction (c), a handful of W nanoparticles existed on the surface; however, a longer process can cause another problem.

[0179] With an extended period, not only do some W nanoparticles remain on the metal catalyst surface, NaOH is also crystalized on the graphene surface.

[0180] Fig. 8 illustrates the results of corresponding experiments in terms of the presence of sodium hydroxide crystals. After 15-min-long reaction (a), a significant number of NaOH crystals were already created on the surface of highly porous graphene with a few W nanoparticles remaining. After 20-min-long reaction (b), even though most W nanoparticles disappeared, an increased number of NaOH crystals were generated on the surface of highly porous graphene. After 30-min-long reaction (c), many big NaOH crystals were created on the surface of highly porous graphene.

[0181] The presence of crystals is problematic as it gives physical contamination of the membrane surface and pores that can lead to blockages and interference with membrane function.

[0182] The crystal debris (with alkaline pH) is further problematic as it can give negative interaction with materials subsequently placed in contact with the graphene surface such as lamination or other supporting layers.

[0183] Further problematic is the inconsistency of processing with the buildup of NaOH crystals with time which leads to a compromise in processing between dissolution of the W particles and formation of the NaOH crystals which leads to less than optimal clearing of the W particles compared to the rapid and residue-free processing of the proposed method, in particular of the Murakami method.

[0184] Furthermore, severe oxidation of the Cu-Ni surface makes the substrate for long treatment times unsuitable for recycling.

[0185] Therefore, a fast kinetics is crucial for a complete removal of W nanoparticles and recycling of metal catalyst.

[0186] Therefore, the slow kinetics of 0.1 M NaOH severely restricts its usability.

[0187] In contrast, when Murakami’s reagent is used, a fast chemical reaction of W nanoparticles into WO3 results in fast dissolution of W nanoparticles within 30 secs without harming the underlying substrate.

[0188] This fast and strong chemical reaction enables a quick complete removal of W nanoparticles, as illustrated in Fig. 9.

[0189] Therefore, the proposed oxidative reagent, in particular Murakimi’s reagent, shows a particular beneficial effect on how fast a reaction kinetics can become by reducing a reaction time from greater than 10 min for NaOH to less than 30 sec with Murakami’s reagent.

[0190] LIST OF REFERENCE SIGNS catalytic substrate, 3 surface of substrate copper / nickel substrate 4 step of growth of the catalytically inactive domains graphene layer on the substrate 13 released bond between 1 and porous graphene layer 5 pore in 5 14 step of application of carrier dissolved oxidant solution, layer 16 Murakami reagent 15 step of thermal annealing aqueous rinsing solution, DI 16 carrier layer water 17 aqueous solution, DI water aqueous persulfate solution, 18 surface of 17 APS solution 19 free floating part of 21 aqueous rinsing solution, DI 20 (still) on-substrate part of 21 water 21 supported released porous tungsten deposition graphene layer contiguous tungsten film layer

Claims

CLAIMS1. Method for making a porous graphene layer (5) of a thickness of less than 100 nm with pores (6) having an average characteristic width as defined in the specification in the range of 1 - 1000 nm, comprising the following steps: providing a catalytically active substrate (1) to catalyse the graphene formation under chemical vapour deposition conditions, said catalytically active substrate (1) on its surface (3) being provided with a plurality of catalytically inactive domains (2) having a nanostructure essentially corresponding to the shape of the pores (6) in the resultant porous graphene layer (5); chemical vapour deposition using a carbon source in the gas phase and formation of the porous graphene layer (5) on the surface (3) of the catalytically active substrate (1), the pores (6) in the porous graphene layer (5) being formed in situ due to the presence of the catalytically inactive domains (2); wherein subsequent to the chemical vapor deposition of the porous graphene layer (5) the porous graphene layer (5) is removed from the substrate (3), in that the exposed porous graphene layer (5) on the surface (3) of the catalytically active substrate (1) is subjected to an aqueous solution containing a dissolved oxidant, directly or indirectly followed by treatment of the exposed porous graphene layer (5) on the surface (3) of the catalytically active substrate (1) with an aqueous persulfate solution, directly or indirectly followed by lamination and / or generation of a carrier layer (16) onto the exposed porous graphene layer (5) from the side opposite to the catalytically active substrate (1) and mechanical separation of said carrier layer (16) with the exposed porous graphene layer (5) from said catalytically active substrate (1).

2. Method according to claim 1 , wherein before treatment with a persulfate solution, the catalytically active substrate (1) with the porous graphene layer (5) is rinsed with water, preferably with distilled water, more preferably repeatedly rinsed with distilled water.

3. Method according to any of the preceding claims, wherein the aqueous solution containing a dissolved oxidant is selected from the group consisting of: an aqueous hydroxide solution comprising ferricyanide, or an acidic solution comprising hydrogenperoxide, wherein preferably the aqueous solution containing a dissolved oxidant is selected from an aqueous sodium and / or potassium hydroxide solution comprising sodium and / or potassium ferricyanide, preferably the aqueous solution containing a dissolved oxidant is consisting of water and aqueous sodium and / or potassium hydroxide and sodium and / or potassium ferricyanide, wherein further preferably in that aqueous solution containing a dissolved oxidant the weight proportion of potassium hydroxide is in the range of 0.05-10%, preferably in the range of 0.1-3% or in the range of 0.3-2% or in the range of 0.5-1.5%, and / or the weight proportion of potassium ferricyanide to water is in the range of 0.05-10%, preferably in the range of 0.1-3% or in the range of 0.3-2% or in the range of 0.5-1.5%, in each case relative to 100% of water used for the preparation of that solution, and / or wherein ration of the weight proportion of potassium hydroxide to the weight proportion of potassium ferricyanide is in the range of 0.2-5, preferably in the range of 0.5- 2 or in the range of 0.8-1.2.

4. Method according to claim 3, wherein the step of treatment with the aqueous solution containing a dissolved oxidant is carried out at a temperature in the range of 15- 35°C, preferably in the range of 20-30°C, and / or over a time span in the range of 0.5-20 minutes, preferably in the range of 1-5 minutes.

5. Method according to any of the preceding claims, wherein said aqueous persulfate solution comprises persulfate selected from the group consisting of: ammonium persulfate, sodium persulfate, potassium persulfate, or a combination thereof, wherein preferably the persulfate concentration is in the range of 0.05-2M, preferably in the range of 0.075- 1.5M.

6. Method according to claim 5, wherein the step of treatment with the aqueous persulfate solution is carried out at a temperature in the range of 15-35°C, preferably in the range of 20-30°C, and / or over a time span in the range of 1-180 seconds, preferably in the range of 5-120 or 5-60 or 5-20 seconds.

7. Method according to any of the preceding claims, wherein directly following the step of treatment with the aqueous persulfate solution, the substrate with the porous graphene layer (5) is rinsed with water, preferably with distilled water, more preferably repeatedly rinsed with distilled water.

8. Method according to any of the preceding claims, wherein mechanical separation of said carrier layer (16) with the exposed porous graphene layer from said substrate is carried out by water intercalation separation, preferably by gradual immersion into water, preferably distilled water.

9. Method according to any of the preceding claims, wherein said carrier layer (16) is a porous carrier layer, preferably the carrier layer is the intended for final use, in particular as a semipermeable membrane, in particular for textile applications in the field of apparel, or in the technical field for providing water barrier in electronics and / or mobile devices.

10. Method according to any of the preceding claims, wherein the catalytically active substrate (1) is a copper-nickel alloy substrate with a copper content in the range of 98 to less than 99.96 % by weight and a nickel content in the range of more than 0.04 to 2% by weight, the copper and nickel contents complementing to 100% by weight of the catalytically active substrate (1), wherein preferably the catalytically active substrate (1) has a nickel content in the range of 0.06 - 1 % by weight or 0.08 - 0.8% by weight complemented to 100% by weight by the copper content.

11. Method according to any of the preceding claims, wherein the aqueous solution containing a dissolved oxidant is an aqueous solution comprising, preferably consisting of, at least one of potassium hydroxide and sodium hydroxide as well as at least one of potassium ferricyanide and sodium ferricyanide, and wherein the concentration of potassium hydroxide is in the range of 0.05-0.4M, preferably in the range of 0.07-0.2M, and wherein the concentration of potassium ferricyanide is in the range of 0.005-0.1 M, preferably in the range of 0.01-0.04M.

12. Graphene layer (5), on at least one carrier layer (16), obtainable or obtained using a method according to any of the preceding claims.

13. Graphene layer (5) according to claim 12, wherein it has a thickness in the range of less than 50 nm, preferably in the range of 1-20 nm, in particular in the range of 5- 15 nm or 7-12 nm and / or wherein it has an areal porosity in the range of at least 10%, preferably at least 15%, more preferably of at least 20% or at least 25% or at least 30% or at least 40%.

14. Piece of textile or apparel having at least one graphene layer (5), preferably on at least one carrier layer (16), made using a method according to any of the preceding claims 1-11 and / or according to any of claims 12 or 13, preferably in the form of a water resistant and / or water repellent and / or breathable apparel.

15. Use of a graphene layer (5), preferably on at least one carrier layer (16), according to any of the preceding claims as a semipermeable membrane, in particular for textile applications in the field of apparel, or in the technical field for providing water barrier in electronics and / or mobile devices.

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