Method for making porous graphene and for post-processing and / or functionalization thereof and graphene obtained using such methods

Abstract

Method for the surface functionalization of a graphene layer of a thickness of less than 200 µm, wherein a (pristine) graphene layer is reacted on at least one side on a surface with a halo-alkylsilane in a hydrolysation condensation reaction under formation of silicone on the surface.

Description

[0001] F07417 20.10.2025

[0002] 1

[0003] TITLE

[0004] METHOD FOR MAKING POROUS GRAPHENE AND FOR POST-PROCESSING AND / OR FUNCTIONALIZATION THEREOF AND GRAPHENE OBTAINED USING

[0005] SUCH METHODS

[0006] TECHNICAL FIELD

[0007] The present invention relates to a method for producing and / or post-processing porous (‘holey’) graphene membranes, in particular those that are waterproof yet highly breathable due to enhanced vapor transmission through the pores perforated within graphene layers. Furthermore, it relates to graphene membranes made using the method and uses of such membranes.

[0008] PRIOR ART

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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 F07417 20.10.2025

[0013] 2 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.

[0014] 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 in a subsequent step.

[0015] 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.

[0016] KR-A-20120081935 and KR-A-101325575 propose to apply a thin metal film layer (Au or Ag) deposited onto the 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.

[0017] 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. 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.

[0018] 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 F07417 20.10.2025

[0019] 3 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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 F07417 20.10.2025

[0025] 4 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.

[0026] 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.

[0027] In summary, the existing technology for the waterproof breathable membranes or generally of porous graphene membranes can be improved and there exists room for improvement and needs for breakthrough technology e.g. to gain vapor breathability (rapid gas phase transport) while maintaining the liquid barrier properties, or other properties and mechanical stability 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.

[0028] Bong et al. in "Bacteria Repellent Properties of Trichlorosilane Self-Assembled Graphene" (2013 Appl. Phys. Express 6 127003) that the bacteria repellent property and thermal stability of pristine graphene and graphene chemically modified with a trichlorosilane (HDF- S) self-assembled monolayer (SAM) were investigated. The contact angles of HDF-S selfassembled graphene (105.8±0.5°) are reported to be improved by ~30% compared with those of pristine graphene (79.4±0.9°). In a bacterial atmosphere, while the bacteria were able to migrate to the pristine graphene surface, they were not able to migrate to the surface of the HDF-S self-assembled graphene. Moreover, the HDF-S SAM on graphene showed stable hydrophobic properties from -40 to 500 °C.

[0029] Shateri-Khalilabad et al in "Preparation of superhydrophobic electroconductive graphene- coated cotton cellulose" (Cellulose (2013) 20:963-972) report a simple and versatile method based on cotton cellulose coated with graphene for the fabrication of superhydrophobic and electroconductive textiles. Graphene oxide was deposited on cotton fibers by a dip-pad-dry method followed by reduction with ascorbic acid to yield a fabric with F07417 20.10.2025

[0030] 5 a layer of graphene. The fabric was then reacted with methyltrichlorosilane to form polymethylsiloxane (PMS) nanofilaments on the fibers surface. The surface chemistry and morphology were characterized by UV-visible reflectance spectrophotometry, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy and scanning electron microscopy. The water contact angle (CA) / shedding angle (SHA) and resistivity measurements were used for assessing hydrophobicity and conductivity, respectively. The graphene-coated fabric showed hydrophobicity with the CA of 143.2° ± 2.9° and SHA of 41 °. The formation of PMS nanofilaments displayed superhydrophobicity with CA of 163° ± 3.4° and SHA of 7°, which indicated the self-cleaning ability. Conductivity of the graphene- coated fabric was confirmed by the electrical resistivity of 91.8 kQ / sq which increased to 112.5 kQ / sq after the formation of PMS nanofilaments. Notably, graphene oxide planar particles according to this disclosure have a different morphology to planar graphene with pores in the layer: edge sites are on outside of graphene oxide flakes whereas porous graphene sheets the edge sites are internal to the planar layer.

[0031] WO-A-2024060525 discloses a fabric-based breathable and washable wearable sensor and a manufacturing method therefor. A nano conductive active material is adsorbed on the surface of an elastic fabric material by means of the interaction between the nano conductive active material and the elastic fabric material, and a hydrophobic layer is formed on the surface by means of hydrophobic modification.

[0032] SUMMARY OF THE INVENTION

[0033] Often termed the “ultimate” membrane, porous or perforated graphene can be a gamechanger for various applications ranging from gas separation to water-proof membrane to oil-water separation. The application of these graphene membranes depends primarily on their pore size distribution, control over this parameter and the absence of any defects during their production is considered critical to preserve their exceptional membrane performance. However, the production of these materials is not without challenges. They are often synthesized via chemical vapor deposition (CVD) on metal catalysts and their assembly requires the transfer from the metallic surface onto a carrier material. During their processing, defects can appear, which can be detrimental to the desired membrane properties. To mitigate these issues and to improve their performance, many efforts have been dedicated to modifying the surface. In this work, we specifically aimed to reinforce the graphene layer by growing silicone-based structures on the surface and simultaneously to modify its wettability. While there has been a lot of contention over the surface properties of graphene, it is generally considered slightly hydrophobic due to the presence of airborne organic contaminants on the surface, while clean free-standing graphene is reported to be F07417 20.10.2025

[0034] 6 hydrophilic. Hence, targeted modifications of their hydrophobic properties can improve their performance specially for water-proof membrane applications and oil water separation. Here, silanes are used to alter the surface properties of graphene surfaces. Silanes have low surface energy, ideal for rendering a surface hydrophobic or even superhydrophobic. However, after the advent of per- and poly-fluoroalkyl substances (PFAS) in the 1940s, silane chemistries were widely overlooked until a decade ago. There is a potential of silane chemistry as a viable alternative to harmful PFAS. A hydrolyzation condensation reaction of halosilanes such as chlorosilanes (especially trichloro silane) either by vapor phase or in liquid phase can be used to introduce filamentary networks of silicones on surfaces. I ntriguingly, water drops deposited on these surfaces show a contact angle of almost 180 ° leading to a virtually perfect spherical shape. These filamentary structures can be optimized by changing process parameters such as solvents, relative humidity, time of reaction, type of silanes.

[0035] A significant gap still exists in transferring silanization processes to the field of chemical vapor-deposited graphene, partly due to their intrinsic chemically inert nature; hence they may require some form of chemical, plasma, and doping treatment prior to the chemical modification to make them receptive by introducing reactive groups in the basal plane. Which in turn, disrupts the sp2 conjugation of the basal plane, essentially changing the properties of the graphene layer that make them so unique and robust. Forming a siloxane network / brushes / monolayer on any surface depends on the presence of reactive groups such as hydroxyls to initiate / accelerate the reaction. In that context, while pristine graphene without any structural defects should not have any reactive group on the surface, porous or holey graphene, on the other hand, can have multiple reactive groups, including -H, -OH, and -COOH, due to the presence of edge type of defects at the pore boundaries. Hence, by exploiting these functional groups, we have introduced / accelerated silicone-based structures on the surface of porous graphene upon silanization.

[0036] In this study, we show that the wetting properties of CVD-synthesized porous graphene can be controlled within minutes by a simple silanization process. Furthermore, by elucidating the kinetics of the silanization reaction, we can also predict the minimum reaction time required to obtain a superhydrophobic CVD synthesized porous graphene. The role of edge defects in the kinetics of the reaction is also high-lighted in this work. When the silanization reaction was carried out on a pristine graphene, drastic differences in the kinetics of the reaction and, consequently, their phenomenological behavior highlighted the role of functional groups in the growth kinetics of the filamentary structures. Additionally, further tweaking of the surface properties could be achieved by infusion of oils, which led to the formation of a slippery-like layer. F07417 20.10.2025

[0037] 7

[0038] This application outlines a simple approach for modifying the wetting properties of graphene surfaces. By varying the silane type, one can obtain different types of morphology on the graphene surface. During the deposition and condensation polymerization process of different types of silanes, e.g. monosilane may form an ultra-thin layer, di-silane form a thicker layer on the surface, and tri-silane form a thick layer consisting of filamentary structures. The filamentary structures formed during the deposition of e.g. tri-silane influences the hydrophobicity of the surface quite remarkably. The low surface energy, along with the hierarchical roughness associated with the filamentary structures, leads to a long-lasting metastable Cassie-Baxter wetting state, which increased the contact angle of water in the process. So, the mono- and di-silane coatings are normally forming monolayer and brush-like layers respectively. Normally these structures are essentially homogeneous coating layers of the polymer molecules packed closely together (effectively forming non- porous interface layers). For a tri-silane coating one important aspect is the formation of fibrillar structural features with void spaces in between the fibrils. The voids form an irregular porous network which is normally distinct from the mono- and di- type coating layers.

[0039] Surprisingly, depending on the presence or absence of pores on the graphene surface, the surface coverage of the filamentary structures differs with identical deposition time of the (tri-)silane, highlighting the role of pore edges in promoting the growth. Aided by the abundance of functional groups present at the edges of the graphene pores, within 15 minutes of deposition of (tri-)silane, one is e.g. able to increase the WCA on these porous graphene surfaces from 90 ° to almost 160 °. When the (tri-)silane is reacted on porous graphene surfaces, an exponential decay of the contact angle hysteresis (CAH) is observed with deposition time, which correlates with a logistic increase of the surface coverage of the filamentary structures, emphasizing the control over the surface properties of these graphene-siloxane hybrid surfaces. One can also identify the vertical growth probability of these filamentary structures, indicating the possibility of thickness control of the “siloxane- filament carpet” on the porous graphene surfaces. A simple approach for fabricating graphene-based SLIPS is also disclosed here, by infusing oil such as silicone oil into a siloxane-filament carpet on the graphene surfaces. One can show that the CAH is < 10° for both high and low surface tension liquids when the filamentary structures are infused with a lubricant.

[0040] The proposed approach is simple, easy to use, and scalable. Additionally, the approach allows for tweaking of surface properties of graphene ranging from superhydrophobic to slippery surface in a controllable manner, which can undoubtedly contribute towards the fabrication of state-of-the-art graphene-based membranes for various applications.

[0041] More generally speaking, according to a first aspect of the present invention, it relates to a F07417 20.10.2025

[0042] 8 method for the surface functionalization of a graphene layer of normally a thickness of less than 200 pm.

[0043] According to the proposed surface functionalization method, a, normally pristine and porous, graphene layer is reacted on at least one side on a surface with a halo-alkylsilane in a hydrolysation condensation reaction under formation of silicone on the surface.

[0044] Preferably, in this reaction no fluorinated reagents (F-compounds) are used, in particular no silane hydrofluoro chain reagent, in particular no heptadecafluoro-1 ,1 ,2,2-tetrahydrodecyl- trichlorosilane (HDF-S).

[0045] Porous graphene plays a key role to achieve what one is aiming for (synergistic technical effect). With pristine graphene having no pores, one can only see a low surface coverage density with scattered and individual filaments, thereby resulting in low contact angle and no slippery characteristics.

[0046] In case of a pristine graphene layer the layer is a graphene layer which previously has not been treated on the surface using this method.

[0047] However, is to be noted that the above-described surface functionalization method can also be applied repeatedly for applying several (same or different) layers of silicone on the surface. Also pre-treated graphene layers can be the starting material for the proposed surface functionalization method.

[0048] The graphene layer can thus already be surface treated to provide for improved reactivity with respect to the silanization agent, so it can for example already have been plasma treated or the like. However, preferably the layer is a pristine graphene layer, which, except for cleaning, is not pretreated prior to applying the above method, so it is normally a graphene layer originating from a CVD process and, if needed, followed by cleaning that surface.

[0049] The halo-alkylsilane is preferably selected as a chloro-alkylsilane and / or as a bromoalkylsilane, preferably having in the range of 1-5, preferably 1-3 preferably fully saturated carbon atoms, wherein preferably the halo-alkylsilane has in the range of 1-3 reactive halogens.

[0050] The halo-alkylsilane is preferably selected as a chloro methyl silane, preferably selected from at least one of the group consisting of: monochloro trimethyl silane, dichloro dimethyl silane, and trichloro methyl silane, wherein preferably trichloro methyl silane is used.

[0051] In particular if trichloro methyl silane is used, the beneficial technical effect of utilizing this compound is to form filamentary structure, resulting in a Cassie-Baxter wetting state. As a result, with no need for harmful F-compounds, one can significantly improve the contact angle up to 1600much better than 1000of the contact angle achieved in the prior art using fluorinated chemistry. Replacing F-compounds and achieving even better contact angle F07417 20.10.2025

[0052] 9 while pores in graphene remaining open is a key contribution for the applications where high contact angle is required without F-compounds.The hydrolysation condensation reaction can be a gas phase or liquid phase reaction, preferably before or after the (pristine) graphene layer has been detached from a catalytically active substrate.

[0053] The hydrolysation condensation reaction can be carried out by immersing or coating (e.g. line coating, spraying or the like, also allowing for a continuous process) the (pristine) graphene layer with a solution of the halo-alkylsilane in a solvent, preferably an organic solvent, more preferably selected from the group consisting of toluene, acetone, ethanol or a mixture thereof.

[0054] In this context, preferably the halo-alkylsilane is selected from at least one of the group consisting of: monochloro trimethyl silane, dichloro dimethyl silane, and trichloro methyl silane, and wherein the halo-alkylsilane is dissolved in an organic solvent, preferably toluene, preferably at a concentration in the range of 0.001-1 g / ml, more preferably in the range of 0.005-0.1 g / ml.

[0055] The hydrolysation condensation reaction is normally carried out for a time span in the range of 1 minute-6 hours, preferably in the range of 3-360 minutes, preferably at a temperature in the range of 10-40°C, more preferably followed by at least one rinsing step with the same or at least one different organic solvent and / or water.

[0056] The (pristine) graphene layer is preferably a porous graphene layer of a thickness of less than 100 nm with pores having an average characteristic width in the range of 1 - 1000 nm. The average characteristic width of the pores is defined and measured as follows:

[0057] 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 holes 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.

[0058] Surprisingly it was found that the porous nature of such a layer is not impaired by the surface functionalization, the surface functionalization only provides for additional properties (super hydrophobicity, slippery properties, mechanical stabilization etc.), but does not impair for F07417 20.10.2025

[0059] 10 example the functionality as concerns water or steam permeability. Such a porous graphene layer is preferably obtained in a method 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] The catalytically active substrate is preferably 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.

[0061] The catalytically active substrate can have 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 catalytically active substrate is preferably prepared by applying, preferably using electrochemical plating, e-beam evaporation, PVD or sputtering, a nickel film of a thickness in the range of 10 nm to 2.2 pm preferably in the range of 25-300 or 20-500 nm, preferably in the range of 50-300 nm on a pure copper foil, preferably having a thickness in the range of 0.01 -0.10mm, preferably in the range of 0.02-0.04 mm, in particular having a purity of more than 99.5%, and by annealing, preferably at a temperature in the range of 800- 1200°C, preferably in the range of 900-1100°C, in particular during a time span of 10 minutes-120minutes, preferably during a time span in the range of 30 minutes-90 minutes. 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.

[0062] The porous graphene layer further preferably has an areal porosity (defined as the ratio of total area of pores to total projected area of the 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 30% or at least 40%.

[0063] The catalytically active substrate is normally provided on its surface with a plurality of catalytically inactive domains by applying, preferably using sputtering, e-beam evaporation or PVD, and essentially contiguous tungsten layer, preferably with 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, and by subsequently annealing at a pressure below normal pressure, preferably of less than 100 mTorr, in particular under a F07417 20.10.2025

[0064] 11 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 (2), wherein preferably 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 50-100 minutes.

[0065] Preferably the catalytically inactive domains have an average characteristic width in the range of 1-1000 nm, preferably in the range of 10 - 100 nm, more preferably in the range of 10-50 nm, or 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.

[0066] Chemical vapour deposition can be carried out 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 using methane gas as carbon source, preferably in the copresence 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, wherein 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.

[0067] The porous or non-porous graphene layer can be removed from the catalytic substrate, and applied to a e.g. porous, preferably nonwoven or fabric supporting substrate, wherein functionalization can be carried out before or after the porous graphene layer has been detached from the catalytically active substrate and before or after being applied to said porous, preferably nonwoven or fabric supporting substrate, preferably in that for removal of the graphene layer first a carrier layer is applied to the graphene layer on the surface opposite to the catalytic substrate and the sandwich of this carrier layer is removed from the catalytic substrate. The carrier layer can by made from a polymeric material, such as PMMA, preferably applied by spin coating. Typically a carrier layer is sufficiently thick and self- supporting, and / or has a thickness of at least 50 nm or in the range of 70-500 nm, preferred thickness in the range of 150-200 nm.

[0068] Preferably prior to removal of the graphene layer, the layered structure of the catalytic substrate with the catalytically inactive domains and the graphene layer are subjected to a pre-leaching process weakening or removing the bond between the graphene layer and the catalytic substrate and / or wherein the catalytically inactive domains.

[0069] Preferably this pre-leaching step includes the formation of an oxide layer at least partially, F07417 20.10.2025

[0070] 12 preferably essentially completely between the graphene layer and the catalytic substrate and the removal of the catalytically inactive domains.

[0071] Preferably the pre-leaching step is subjected to a basic or acidic environment, preferably in water, more preferably at a pH of less than 6 or more than 7, preferably more than 10, more preferably at a pH of more than 12, wherein most preferably an aqueous solution of 0.01- 0.5 M NaOH is used, preferably for a time span in the range of 10-60 minutes at a temperature in the range of 40-60°C, optionally followed by rinsing with water and drying.

[0072] Subsequent to the chemical vapor deposition of the porous graphene layer the (porous) graphene layer can be removed from the substrate, in that the exposed (porous or non-porous) graphene layer on the surface of the catalytically active substrate is subjected to an aqueous solution containing a dissolved oxidant, directly or indirectly followed by treatment of the exposed (porous or non-porous) graphene layer on the surface of the catalytically active substrate with an aqueous persulfate solution, directly or indirectly followed by lamination and / or generation of a carrier layer onto the exposed (porous or non-porous) graphene layer from the side opposite to the catalytically active substrate and mechanical separation of said carrier layer with the exposed (porous or non-porous) graphene layer from said catalytically active substrate.

[0073] The graphene layer can be removed, preferably after a pre-leaching step, using electrochemical methods, by immersing the layered structure of the catalytic substrate with the catalytically inactive domains and the graphene layer in an electrolyte and applying electrochemical potential to the substrate relative to a counterelectrode in the same electrolyte.

[0074] On the functionalized surface the silanization preferably takes the form of a layer of individual or interconnected filaments (in particular when treating with polychloro alkylsilane such as trichloromethylsilane), and wherein the voids in that layer are filled with a liquid, preferably a viscous liquid and / or a silicon oil (e.g. by immersion under normal or elevated temperature).

[0075] Furthermore, the present invention relates to a graphene layer, preferably on at least one supporting substrate, obtainable or obtained using a method according to the above description.

[0076] Preferably the layer 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.

[0077] Preferably the layer 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%.

[0078] Preferably on the functionalized surface the silanization takes the form of a layer of F07417 20.10.2025

[0079] 13 individual or interconnected filaments, and the voids in that layer are filled with a liquid, preferably a viscous liquid and / or a silicon oil.

[0080] Furthermore, the present invention relates to a piece of textile or apparel having at least one graphene layer made using such a method and / or according to the above, preferably in the form of a filtering or separation device or a water resistant and / or water repellent and / or breathable apparel.

[0081] Also, the present invention relates to a use of such a graphene layer as a membrane, preferably semipermeable membrane, in particular for filtering, separation or textile applications in the field of apparel, or in the technical field, in particular for superhydrophobic or and / or slippery surface properties, including providing water barrier in electronics including batteries and / or mobile devices.

[0082] Further embodiments of the invention are laid down in the dependent claims.

[0083] BRIEF DESCRIPTION OF THE DRAWINGS

[0084] 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,

[0085] Fig. 1 shows a schematic diagram of the silane deposition process;

[0086] Fig. 2 shows the influence of siloxane deposition on the wettability of the graphene surface: (i) contact angle of water measured on untreated and treated Gr / Copper plotted as a function of type of treatment (mono / di-silane / tri-silane); (ii) snapshots of the measurements visually representing the different behaviour of water upon treatment: (a) untreated sample, (b) Monosilane-, (c) Di-silane-, and (d) Tri-silane-treated;

[0087] Fig. 4 shows the influence of tri-silane reaction time on their phenomenological behaviour: (i) advancing (square) and receding (up triangle) contact angle of water plotted as a function of silane deposition time; the CAH is plotted in the right y-axis as a function of deposition time; (ii) snapshots of the contact angle measurements advancing (right) receding (left) with varying tri-silane reaction time (0 min to 60 min); the experiments were carried out after transferring the porous graphene layer from metal catalyst onto silicon oxide substrates; (iii) advancing (square) and receding (up triangle) contact angle of water plotted as a function of silane deposition time; the CAH is plotted in the right y-axis as a function of deposition time; (iv) snap-shots of the contact angle measurements advancing (right) receding (left) with varying tri-silane reaction time (0 min to 60 min); the experiments were carried out on the porous graphene layer on the F07417 20.10.2025

[0088] 14 metal catalyst;

[0089] Fig. 5 shows the influence of tri-silane deposition time on the surface coverage of the filamentary structures; (i) surface density of the filamentary structures on the surface plotted as a function of deposition time; the CAH measurements are plotted at the right y-axis, which shows a clear correlation between CAH measurements and the measured CAH of water; (ii) the SEM images of the transferred graphene surface after (a) 0 min, (b) 5 min, (c) 15 min, (d) 30 min, and (e) 60 minutes of tri-silane reaction; from the SEM images one can clearly identify changes in the surface coverage of the filamentary structures with varying reaction time;

[0090] Fig. 6 shows in (i) (a) dynamic contact angle of water plotted as a function of reaction time of tri-silane on pristine graphene (without any treatment) transferred on silicon oxide substrates; snapshots of advancing (left) and receding (right) contact angle of water on pristine graphene surfaces after (c) 0 minutes (no trisilane reaction), (d) 30 minutes, and (e) 60 minutes of tri-silane reaction, (ii) Comparison of CAH of water as a function of reaction time (minutes) between pristine (blue circles) and porous (faded red circle) graphene;

[0091] Fig. 7 shows in (i) (a-b) large scale and (c) small scale SEM images of the pristine graphene surface after 1 hour of reaction time with tri silane which show sporadic formation of filamentary structures; (ii) (a-b) large scale and (c) small scale SEM images of the porous graphene surface after 1 hour of reaction time with tri silane demonstrating homogeneous formation of filamentary structures on the graphene surfaces creating a type of “silicone-filament” carpet on graphene mimicking the “lotus-leaf” effect;

[0092] Fig. 8 shows in (i) average roughness (Ra, faded grey) and the RMS roughness (Rq, black) of the layer of silica filament like structures grown on SLPG graphene as a function of reaction time; (ii) roughness parameter (RZ) plotted as a function of reaction time; (iii) corresponding FTIR spectra of the graphene surface modified with tri-silane for different times; the peak observed at wavenumber 2962 cm-1 indicates the presence of -CH3 groups and peak observed at wavenumber 1260 cm-1 originates from the symmetric deformation of methyl groups in Si- CH3 indicating the presence of silanes on the graphene surface; (iv) integrated peak areas of peak 1 and 2 plotted with respect to reaction time (minutes) showing a systematic increase over time indicating increased formation of the filamentary structures;

[0093] Fig. 9 shows SEM images of porous graphene on the metal catalyst after reacting with F07417 20.10.2025

[0094] 15 tri silane for (a) 0 min, (b) 3 min, (c) 5 min, (d) 10 min, (e) 15 min, (f) 30 min, (g) 45 min, and (g) 60 min;

[0095] Fig. 10 shows large scale SEM images of porous graphene transferred on the silicon oxide substrates after reacting with tri silane for (a) 5 min, (b) 15 min, (c) 30 min, and (d) 60 min;

[0096] Fig. 11 shows height (top row) and intensity (bottom row) images obtained by confocal laser scanning microscopy of transferred porous graphene films treated with trisilane for (a) 0 min, (b) 5 min, (c) 15 min, (d) 30 min, and (e) 60 min. The sizes of the images are (25 x 32) pm2; the lines indicate where the line roughnesses were measured to obtain Ra, Rq, and Rz values;

[0097] Fig. 12 shows observations of a slippery graphene-based layer; (A) (a-b) top view and (c) cross-section of the tri-silane modified (reaction time ca. 240 minutes) graphene surface visualized through SEM; the scale bars are specified in each image; the cross-section image clearly shows that the thickness of the filamentary silane layer is > 5 pm; (B) the dynamic contact angle and contact angle hysteresis (CAH) of ethylene glycol (y = 48 mN / m) and water (y = 72 mN / m) on tri-silane modified graphene before and after infusion of silicone oil; (C) snapshots of advancing and receding water (a, c) and ethylene glycol (b, d) droplets before (a, b) and after (c, d) the infusion of silicone oil.

[0098] DESCRIPTION OF PREFERRED EMBODIMENTS

[0099] Materials and Methods:

[0100] Fig. 1 shows a schematic diagram of the silane deposition process, the details of the individual steps are given in the following.

[0101] Synthesis of porous graphene:

[0102] The synthesis of chemical vapor deposited (OVD) porous graphene is mentioned in detail e.g. in WO2017212039 or in WO2021121952 reference is made to these disclosures for the general technology.

[0103] The method used here follows a bottom-up approach where nanoparticles of tungsten (W) are formed on top of the copper (Cu) catalyst. The graphene is subsequently synthesized by CVD on the W free area of the catalyst leaving pores upon the removal of the W nanoparticles (droplets) at the end of the process.

[0104] In brief, a W film of 2 nm thickness was sputter coated on bare Cu foil (JX Metals Corporation, 99.9% purity) using FHR Pentaco 100 at a pressure of 0.002 mbar, with 100 standard cubic centimetres per minute (seem) of Ar under 0.25 kW of DC plasma. Before the CVD process, the Cu foil (Alfa Aesar 46986, 99.8% purity) was treated with an Ar-ion F07417 20.10.2025

[0105] 16 beam for 10 minutes. The treated W / Cu catalyst was kept within a Cu envelope (Alfa Aesar 46986) for further processing. The W / Cu catalyst in the Cu foil envelope was placed at the centre of a low-pressure chemical vapor deposition (CVD) furnace. The W / Cu in the Cu envelope is annealed first at a 950 °C in the CVD chamber for 30 minutes under a flow of 50 seem of H2 which allows for the spinodal dewetting of the W layer resulting in smaller droplets on the catalyst. Then the methane source is introduced after the annealing process in the CVD chamber. Graphene synthesis was initiated at the identical elevated temperature by introducing a mixture of 4 seem of CH4 and 50 seem of H2 at 800 mTorr for 10 minutes. The sample was then gradually cooled to room temperature while maintaining a flow of 100 seem of H2. Nucleation and growth of graphene is inhibited in the areas where W droplets are present resulting in the formation of pores when the graphene is transferred to a desired substrate.

[0106] Synthesis of pristine graphene:

[0107] For the synthesis of non-porous / pristine graphene the copper catalyst was purchased from JX Metals. In this case, the Cu could be used as received (without pretreatment) for the synthesis process. A small part of the foil was cut and placed at the centre of the CVD furnace. Here, the annealing of the Cu was done at 1000 °C for 20 minutes under a flow of 50 seem of H2. Subsequently, the graphene was synthesized at an identical temperature by introducing a mixture of 50 seem of CH4 and 10 seem of H2 flow for 45 minutes. After the growth was completed, the sample was gradually cooled down to room temperature with 20 seem and 100 seem of H2 and Ar flow, respectively.

[0108] Transfer of graphene onto silicon substrates:

[0109] An etching process was used here to transfer the graphene from the metal catalyst. This kind of transfer process of graphene requires a supporting layer to prevent the layer from disintegrating and to minimize transfer induced defects.

[0110] For the transfer process, a sufficiently thick layer of spin-coated poly(methylmethacrylate) (PMMA, typically having a thickness of at least 50 nm or in the range of 70-500 nm, preferred thickness in the range of 150-200 nm) was used as a supporting layer. The Cu catalyst and the W droplets were etched by floating the samples (with spin coated PMMA layer) on an aqueous 0.5M ammonium persulfate (NH4)2S20s (APS, Sigma-Aldrich) bath with the Cu side at the interface (for the etching method reference is made to the disclosure in WO2021121952, alternatively a method as disclosed in PCT / EP2024 / 076852 can be used, both disclosures are included as for the etching process). After 10 minutes, the samples were washed with water and wiped with lint-free tissue to remove the backside graphene formed during the CVD process. Afterward, the samples were placed back on the etching bath for 3 hrs. The sample was then floated on a water bath for 1 hour to remove F07417 20.10.2025

[0111] 17 the APS residues when no copper residue was visible on the sample.

[0112] The sample was then picked up using a silicon dioxide substrate. The silicon substrate used was a piece of silicon wafer with a silicon dioxide surface layer (SiC>2 depth is about 280nm). The starting wafer size is generally 4 inches diameter and ca. 500 pm overall thickness. The cut piece used in the experiments is typically 1 x 1 cm2. The pick-up angle was 45° to ensure conformal adhesion of the graphene with the substrate. After sufficient drying, the PMMA layer was dissolved by placing the sample in an acetone bath (Sigma-Alrich) for 1 hour, and then the sample was dried with nitrogen flow.

[0113] Growth of siloxane filaments:

[0114] Silinized-Graphene samples were prepared by immersion in a silane / toluene solution. Monochloro trimethyl silane (Monosilane), Dichloro dimethyl silane (Di-silane), and Trichloro methyl silane (Tri-silane) and solvents such as toluene, acetone, and ethanol (all HPLC grade) were purchased from Sigma Aldrich. The concentration of silane in toluene was kept constant in all cases at 0.01 g / ml. Toluene was chosen as the desired solvent for the deposition process due to the low water solubility and content in order to prevent rapid hydrolysis of the chlorosilanes. The samples, (i) graphene as prepared on copper catalyst and (ii) graphene transferred to silicon substrate by etching process, were immersed in the 0.01 g / ml of chlorosilane / toluene solution for varying time periods ranging from 3 minutes to 4 hours maximum. After immersion, the samples were rinsed immediately by a jet flow of acetone for 30 seconds, followed by a cleaning jet flow with water and subsequently ethanol for 30 seconds, respectively. The order of the rinsing process is kept constant throughout this study. The cleaning process removes both the excess and unreacted silanes from the surface. After the cleaning process the samples were dried under an argon / nitrogen flow at room temperature (30 s).

[0115] Contact angle measurements:

[0116] The dynamic contact angle measurements were carried out by increasing (advancing) and reducing (receding) the volume of a sessile drop (Kruss DSA 10 mK2 drop shape analyser system). After placing a sessile drop of 2 pl in volume on the sample's surface (using a 0.5 mm diameter syringe needle), 6 pl of the desired liquid was continuously dosed at a rate of 20 pl / min. A video was recorded of the drop during the dosing process (CCD camera, 12.5 fps, total number of frames = 180) to measure the advancing contact angle. After the dosing process, the liquid was retracted at an identical rate, and another video was recorded with identical parameters during the retraction process. Each frame of the video was analysed using the drop shape analyser software, and the tangent method was used to measure the contact angle of each frame. The contact angle values presented here were averaged from all the frames acquired during the measurement, where the error bars represent the F07417 20.10.2025

[0117] 18 variation of contact angles within the acquired frames.

[0118] Results:

[0119] Three different types of silanes, namely trichloromethyl silane (Tri-silane), dichlorodimethyl silane (Di-silane), and monochloro trimethyl silane (Mono-silane) were reacted on porous graphene surfaces. As the name tells, these silanes have three, two, or one hydrolysable chlorine atoms. The hydrolysis of the Cl-group into a hydroxyl is responsible for the growth of different silane structures. Upon hydrolysis, condensation polymerization of the hydroxy silanes and elimination of water leads to continuous growth of siloxane structures. Depending on the silane type, either monolayer, brush layer, or network-type layers can be grown. In this framework, we deposited three types of silanes during 1 hr on as-grown porous graphene surface still attached onto the catalyst and porous graphene after transfer on a flat silicon substrate. The deposition procedure and removal of excess silanes after the deposition are given above.

[0120] The influence of silane layer morphology and conformation on their phenomenological behaviour was identified, which in this case is surface wettability. In this context, the dynamic contact angle of water after the deposition was measured and compared with the untreated surface.

[0121] Fig. 2 shows the influence of siloxane condensation and deposition on the dynamic contact angle of water. Graphene on a copper substrate shows an advancing contact angle of (84.2 ± 2.3)° with very high contact angle hysteresis (28.4 ± 0.4)°. The advancing contact angle is somewhat similar to the static contact angle and contact angle hysteresis indicates the ability of a drop to roll off (it is a qualitative indicator of the kinetic barrier associated with the removal of the contact line from a surface). To term a surface as superhydrophobic, it has to have a water contact angle of > 150° with a contact angle hysteresis (CAH) of less than 10°, while slippery surfaces should show low CAH (< 10°) to even low surface tension liquids. Hence, we focused on measuring both contact angle and contact angle hysteresis. In this case, we measured the dynamic contact angle of water after the deposition of different silanes. Di-type silane and mono-type silane did not demonstrate significant changes in the advancing contact angle. However, we could identify an increased receding contact angle, indicating the possibility of a type layer on the surface of graphene. Interestingly, a significant increase in the dynamic contact angle of water was observed with the introduction of tri-silane on the graphene layer. Starting from (84.2 ± 2.3)°, the advancing water contact angle of water increased to ca. (151 .2 ± 2.4)° with the introduction of tri-silane. More significantly, the CAH of water was as low as 9°, indicating the possibility of easy drop roll-off. Such a high contact angle of water points to a roughness-induced contact angle originating from the Cassie-Baxter wetting state. Young's contact angle of water on a F07417 20.10.2025

[0122] 19 surface of PDMS is usually 105° - 110°.

[0123] To understand the origin of the significantly high contact angle associated with the tri-silane deposition process, we analysed the surface of the graphene with varying silane deposition and compared it with graphene on copper. Scanning electron microscopy (SEM) was used to investigate the changes in the morphological features of the graphene surface with the deposition of three types of silanes (deposition time = 1 hr) to establish a correlation with their phenomenological behaviour.

[0124] As one can see from Fig. 3, the SEM images of the graphene on the metal catalyst show the presence of tungsten nanoparticles (needed for the pore formation) and a wrinkled graphene layer. The wrinkling phenomenon of graphene on copper surfaces during its synthesis is often observed due to its higher thermal expansion coefficient than copper. Monosilane has only one reactive / hydrolysable group. Hence, when the chlorine atom hydrolyses in presence of water, it can only form monolayer domains along the defect sites / pore edges as condensation in this case cannot occur due to the structural constraint as one can see in a). Consistently SEM images of the graphene layer obtained after the deposition of monosilane still show the presence of both the tungsten nanoparticles and the wrinkled regions of the graphene, indicating a thin mono-siloxane layer on the surface. SEM images of the di-silane deposited sample show the tungsten particles. However, the wrinkling features of the graphene film diminished noticeably after the condensation of the di-silane on the surface, indicating the presence of a thicker layer consistent with a brush layer growth. It is to be noted that due to the presence of two chlorine atoms, the condensation polymerization after the hydrolysis can occur only in one direction (growth due to constraint) resulting in a linear brush layer growth (see b).

[0125] The tri-silane deposited graphene surface showed the presence of filamentary structures. Tri-type silane tends to form filamentary structures due to a combination of the fast growth process and its reactivity. Compared to their di- or mono- counterparts, the presence of three hydrolysable chlorine atoms in tri-silane makes them highly reactive (schematic in c). Hence, from a point of view of structure formation, the growth in this case occurs rapidly and in a random manner due to considerably higher degree of freedom of polymerization during the condensation process, which facilitates the formation of fibrillar structures. Through SEM analysis, we can observe a porous siloxane layer aided by the networks of filaments. The porosity of the surface originating from the tortuous arrangement of siloxane filaments promotes the formation of air pockets upon liquid droplet deposition, hence enabling the Cassie-Baxter wetting state. Notably, we also did not observe any changes in the contact angle value during the measurements, highlighting the absence of any transition from the Cassie-Baxter wetting state to the Wenzel wetting state, indicating a long-living F07417 20.10.2025

[0126] 20 metastable Cassie-Baxter wetting state. Furthermore, these filamentary siloxane structures covered the whole surface of graphene, demonstrating the homogeneity of the layer formation on graphene. Based on the findings of the three silane types, focus was put on determining the kinetics of the deposition of the tri-type silane due to its exceptional superhydrophobic behaviour.

[0127] Focusing on the deposition of these filamentary structures, the influence of the growth time on the homogeneity of the filamentary structures observed on the graphene film was investigated. Therefore, we varied the deposition time systematically from 0 hr to 1 hr. We deposited the silanes before and after the transfer of the porous graphene from the copper catalyst on silicon oxide (300 nm) substrates (without any surface treatment) to exclude the possible influence of copper / copper oxide from the growth mechanism of the filamentary structures. We measured a very low water contact angle and very high CAH when no silane was deposited. Already after 3 minutes reaction time, we observed a noticeable increase in the water contact angle. However, the CAH was still very high, but was eventually reduced to < 5° after extension of the reaction time to 15 minutes. Interestingly, when plotting CAH as a function of reaction time (Fig. 4. i and iii), an exponential decay was observed. The following relation could be used to identify the influence of silane deposition time on their phenomenological behaviour (CAH):

[0128] CAHt= CAHf+ CAH0Xexp-0-2*time where CAHt indicates the CAH measured at time t, CAHo is the CAH measured at time 0 (untreated surface), and CAHt is the CAH measured at the final time point of the reaction (in this case 3600 s). The equation was used to fit the CAH plot obtained during measurements, where we could identify that CAH decreased exponentially with an exponent of ca. -0.2. CAH is a phenomenological implication of the changes in the morphological and chemical features of the porous graphene surfaces. Hence, to understand this behaviour, one needs to elucidate the influence of the structural changes in the graphene film with the reaction time of tri-silane. So far, it was established that the exceptionally low CAH and WCA can be associated with the presence of filamentary structures on the graphene film. Consequently, the influence of reaction time on the filamentary structures was investigated via scanning electron microscopy.

[0129] First the changes in the morphological features of the graphene surface with varying times of silane reaction on both graphene on copper catalyst and graphene after transfer on SiO2 substrate were investigated as shown in Fig. 4. The SEM images revealed increased surface density of the filamentary structures with increased reaction time. We could detect very few filamentary structures with 3 to 5 minutes of reaction time in both cases (surface coverage ca. (30.5 ± 5.3) %). We analysed the samples where the silane was reacted on F07417 20.10.2025

[0130] 21 the transferred graphene with Imaged to quantify the surface covered by the filamentary structures with varying deposition times. After plotting the surface covered by structures as a function of time, we could accurately correlate the percentage of coverage with the measured CAH data. As the area covered by the filamentary structure increased, the contact angle hysteresis decreased. While the surface coverage of the filamentary structures followed a logistic increase, the CAH followed an exponential decay with varying reaction times (see Fig. 5). We could achieve WCA as high as (157.3 ± 0.4)° and CAH as low as (1 .5 ± 1.4)° with (78.8 ± 6.4)% surface coverage of these filamentary structures within 30 minutes of reaction. As discussed earlier, the CAH determines the ability of the drop to roll off a surface; for example, low CAH of water on lotus leaves makes them superhydrophobic and self-cleaning. The origin of low CAH of superhydrophobic surfaces is often attributed to hierarchical structures (roughness at different length scales); here, the filamentary structure of the partially networked methyl siloxane provides the hierarchy necessary for easy roll-off. Hence, with increasing filamentary structures, we can observe decreasing CAH on CVD graphene surfaces allowing for precise tailoring of their wetting properties within 30 minutes of treatment.

[0131] It is worth noting that when the identical reaction of tri-silane on transferred pristine graphene surfaces (graphene without any pores) was carried out, the superhydrophobic effect was not so evident, notably since the CAH remained very high even with 1 hr of deposition time (see Fig. 6 and 7). Further analysis with SEM revealed the presence of uneven surface coverage of the filamentary structures even after 1 hour of deposition. Such an observation suggests that the edge defects on the porous surface can most likely accelerate the formation of the filamentary structures during the reaction of tri-silane.

[0132] While one can observe the logistic growth of the filamentary structures with increasing deposition time, there is still a probability of growth of the filamentary structures in the z- direction. Hence, it is important to investigate the growth likelihood perpendicular to the surface. Thus, we opted for confocal laser scanning microscopy (CLSM) to obtain the roughness changes associated with tri-silane deposition. Work on CLSM on CVD graphene surfaces demonstrated its efficiency in measuring parameters such as thickness variation, wrinkling, and roughness. The roughness was calculated by using line roughness (line length = 32 pm, minimum 20 measurements). The average roughness (Ra) and the rms roughness (Rq) of untreated surface were ca. 2.45 nm and ca. 3.1 nm respectively, consistent with single layer or few layers porous graphene surfaces. Significant increase in the roughness values was observed with varying silane reaction times. Higher roughness indicates growth in the z-direction due to the presence of fibres, further increase in the roughness values observed with increasing reaction times might explain the logistic growth F07417 20.10.2025

[0133] 22 observed in this study. When we plotted both Rq and Ra as a function of reaction time (Fig. 8.i), we could observe an exponential growth with time (Fig. 8.i). Additionally, we also calculated the maximum height of the layers (RZ) which also showed exponential growth over time (Fig. 8.ii), implying that while the surface coverage in the x-y direction reached a plateau within 15 minutes, the filamentary structures continued to grow vertically (as evident by the exponential increase of roughness with time), pointing to the potential of continuous growth of silane filament carpet.

[0134] Additionally, we measured the FTIR spectra (at a grazing angle of 83°) of the graphene surfaces with varying deposition times (Fig. 8. iii) using agilent Spectrometer Cary 680 and Agilent Microscope 620 with a grazing angle objective (128 scans and a spectral resolution of 4 cm-1). We used the samples transferred onto a silicon oxide substrate for roughness measurements and the FTIR analysis. Hence, we focused our analysis on determining the content of hydrophobic radicals. From the FTIR spectra, we could identify two peaks associated with the growth of the filamentary structures: one associated with the stretching vibration of the CH bonds at 2962 cm-1 related to the methyl groups and the other associated with the symmetric deformation of CH3 in the Si-CH3 groups at 1259 cm-1. The Si-CH3 groups are associated to the partially networked methyl siloxane chains formed during the polymerization condensation process of the tri-silane. The notable absence of these two peaks in the spectra of the untreated porous graphene surface confirmed conclusively that these two peaks indeed originate from the filamentary structures. As such they can be tracked to follow the siloxane grow reaction on the porous graphene surface.

[0135] The intensity of the two peaks is associated with the systematic increase in deposition time (shown in Fig. 8.iv). The area under the peak at 2962 and 1260 cm-1 was integrated. We could observe a systematic increase in their area with the increase in the deposition time that is associated to the growing of filaments with increasing reaction time. The correlation between the roughness measurements and the FTIR spectra over time points further explicitly to the vertical growth of the filaments with increasing time of deposition. This follows from the increased pathlength of the IR beam through the filamentous structure in the grazing angle FTIR set up. Our observations suggest that not only the surface coverage but also the thickness of the filamentary layer can be controlled by the reaction time, which might be critical in the design of graphene-based waterproof membranes (specifically for properties such as hydrostatic pressure).

[0136] SEM images of the graphene surfaces on copper after varying reaction time of tri-silane: As-synthesized porous graphene surfaces on copper were treated with varying reaction times of tri-silane (0 minutes to 60 minutes), and both dynamic contact angles of water and SEM images were measured of the samples. From the SEM images as given in Fig. 9, F07417 20.10.2025

[0137] 23 systematic change in the surface density of the filamentary structures could be observed. The as-synthesized porous graphene on copper shows two morphological features: (i) the tungsten nanoparticles formed during the annealing process (where pores are formed) and (ii) the wrinkled graphene film. Filamentary structures on the graphene surface could be observed upon treatment of the tri-silane. Furthermore, with 3 and 5 minutes of treatment, we could only observe a few filamentary structures, which increased considerably with 15 minutes of treatment, consistent with the measured dynamic contact angle where both CAH and WCA increased substantially after 15 minutes of reaction.

[0138] Additional large scale SEM images of the graphene surfaces on silicon after varying reaction time of tri-silane'.

[0139] Large-scale SEM images of the transferred graphene on silicon substrates after varying reaction times of tri-silane as shown in Fig. 10 clearly show the varying surface densities of the filamentary structures on the graphene surface. While irregular coverage of the filamentary structures at 5 minutes was observed (leading to a high CAH), 30 minutes and 60 minutes reaction show homogeneous carpet filaments mimicking quite clearly the hierarchical structures observed in lotus leaves. The large-scale images obtained here establish the control over the surface density of the filamentary structures formed on the surface, further demonstrating the precise control over the wettability of porous graphene surfaces.

[0140] Line roughness measurement with CLSM:

[0141] Identical image sizes were used to measure the roughness of the samples. The image sizes were (25 x 32) pm2. Here, we have used a minimum of 20 line roughness measurements to calculate the average roughness (Ra), rms roughness (Rrms), and maximum height reported here. The images used for the measurements are shown in Fig. 11 . Both the height and intensity images obtained by CLSM measurements indicate the varying roughness of the samples with increasing tri-silane reaction time. Notably, on the untreated surface, we can identify the edges of the graphene domains, and the homogeneous thickness of the layer is very evident and consistent with CVD-synthesized graphene further confirming the reliability of the measurements. With 5 minutes of tri-silane reaction, the appearance of thicker domains in both height and intensity images can be identified. However, these domains are present in random areas on the sample, consistent with the morphological features observed by SEM. With increasing reaction time, a clear increase in the roughness and an apparent increase in thicker domains were observed. Interestingly, we could identify a significant change in the roughness when the reaction time was increased from 30 minutes to 60 minutes, pointing towards the vertical growth of these filamentary structures with time. F07417 20.10.2025

[0142] 24

[0143] SUPS surfaces:

[0144] While superhydrophobic properties on a graphene surface opens the pathway to myriads of functional membrane applications, we also aimed to explore the potential of making graphene-based surfaces repellent to low surface tension liquids. One of many explored omni-repellent surfaces, Slippery Liquid Infused Porous Surfaces or SLIPS have been quite prominent due to their simplistic approach and elegant physics. SLIPS is a bioinspired surface mimicking the slippery nature of the Nepenthes Pitcher plant, where the patterned leaves surfaces are usually infused with water, leading to insects slipping in the plant funnel after landing on the leaf.

[0145] We wanted first to grow the filamentary structures as thick as possible to minimize the leaching of the oil from the structures; hence, the reaction time was increased to 4 hrs. After 4 hours of reaction with tri-silane, we observed a carpet of these filamentary structures as thick as 5 pm in some regions (Fig. 12.i(a-c)). Next, we infused these structures with a silicone oil of relatively lower viscosity (100 cSt), and we could observe effective spreading of the oil on the surface pointing to the infusion. The samples were kept under vacuum and then rinsed with water to remove the excess oil. We measured the dynamic contact angle of both water and ethylene glycol. We deliberately chose two liquids with very different surface tension, one representing the highest possible and the other representing the lower surface tension liquids. Before the infusion of oil, the advancing water contact angle was almost 152°, and the CAH was 3°, demonstrating a lotus leaf-type effect. When we deposited a drop of ethylene glycol (y = 48 mN / m), the drop spread quickly on the surface with an advancing contact angle of 31 ° and the CAH of 15°. Such a high CAH indicates a spreading behaviour of low surface tension liquids, possibly indicating a transition of Cassie- Baxter to Wenzel state. Consistent with what previous works have observed in the lotusleaf effect, these surfaces are ineffective for low surface tension liquids due to a relatively unstable Cassie-Baxter state, leading to a transition to the Wenzel state as the liquid penetrates the porous structure.

[0146] Notably, we observed a very different wetting behaviour of both water and ethylene glycol after the infusion of oil. The advancing contact angle of water reduced significantly after the infusion of oil. Still, the CAH of water remained < 10 °, which is indicative of a slippery surface. Furthermore, we also didn’t observe any cloaking of the oil in the water droplet during the measurement. When ethylene glycol drops were dosed on the surface, we observed a noticeably higher advancing contact angle, indicating no penetration of the drop, and the CAH remained less than 10 °. Lower CAH and high contact angle of ethylene glycol points to a liquid / liquid interface where the angle of ethylene glycol drop arises from the classical young’s contact angle on a liquid / liquid interface. This work provides the first F07417 20.10.2025

[0147] 25 description for fabricating graphene-based SLIPS. The findings demonstrate the possibility of modifying graphene surfaces focused on various coating applications specifically for water / oil repel lence.

[0148] LIST OF REFERENCE SIGNS

[0149] APS ammonium persulfate

[0150] CAH contact angle hysteresis

[0151] CLSM confocal laser scanning microscopy

[0152] Cu copper

[0153] CVD chemical vapor deposition / deposited

[0154] Gr graphene

[0155] SEM Scanning electron microscopy

[0156] PMMA poly(methylmethacrylate)

[0157] SLIPS Slippery Liquid Infused Porous Surfaces

[0158] W tungsten

[0159] WCA water contact angle

Claims

F07417 20.10.202526CLAIMS1 . Method for the surface functionalization of a graphene layer of a thickness of less than 200 pm, wherein the graphene layer, in the form of a pristine graphene layer, is 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, wherein this graphene layer is reacted on at least one side on a surface with a halo-alkylsilane in a hydrolysation condensation reaction under formation of silicone on the surface.

2. Method according to claim 1 , wherein the halo-alkylsilane is selected as a chloro-alkylsilane and / or as a bromo-alkylsilane, preferably having in the range of 1-5, preferably 1-3 preferably fully saturated carbon atoms, wherein preferably the halo- alkylsilane has in the range of 1-3 reactive halogens.

3. Method according to any of the preceding claims, wherein the halo- alkylsilane is selected as a chloro methyl silane, preferably selected from at least one of the group consisting of: monochloro trimethyl silane, dichloro dimethyl silane, and trichloro methyl silane, wherein preferably trichloro methyl silane is used.

4. Method according to any of the preceding claims, wherein the hydrolysation condensation reaction is a gas phase or liquid phase reaction, preferably before or after the graphene layer has been detached from a catalytically active substrate.

5. Method according to any of the preceding claims, wherein the hydrolysation condensation reaction is carried out by immersing or coating the graphene layer with a solution of the halo-alkylsilane in a solvent, preferably an organic solvent, more preferably selected from the group consisting of toluene, acetone, ethanol or a mixture thereof.

6. Method according to claim 5, wherein the halo-alkylsilane is selected from at least one of the group consisting of: monochloro trimethyl silane, dichloro dimethyl silane, and trichloro methyl silane, and wherein the halo-alkylsilane is dissolved in an organic solvent, preferably toluene, preferably at a concentration in the range of 0.001-1 g / ml, more preferably in the range of 0.005-0.1 g / ml.F07417 20.10.2025277. Method according to any of the preceding claims 5 or 6, wherein the hydrolysation condensation reaction is carried out for a time span in the range of 1 minute- 6 hours, preferably in the range of 3-360 minutes, preferably at a temperature in the range of 10-40°C, more preferably followed by at least one rinsing step with the same or at least one different organic solvent and / or water.

8. Method according to any of the preceding claims, wherein the graphene layer is obtained in a method 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.

9. Method according to claim 8, 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 to 2% by weight, the copper and nickel contents complementing to 100% by weight of the catalytically active substrate, 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, and / or wherein the catalytically active substrate is prepared by applying, preferably using electrochemical plating, e-beam evaporation, PVD or sputtering, a nickel film of a thickness in the range of 10 nm to 2.2 pm preferably in the range of 25-300 or 20-500 nm, preferably in the range of 50-300 nm on a pure copper foil, preferably having a thickness in the range of 0.01 -0.10mm, preferably in the range of 0.02-0.04 mm, in particular having a purity of more than 99.5%, and by annealing, preferably at a temperature in the range of 800-1200°C, preferably in the range of 900-1100°C, in particular during a time span of 10 minutes-120minutes, preferably during a time span in the range of 30 minutes-90 minutes.

10. Method according to any of the preceding claims 8 or 9, wherein the porous graphene layer has a thickness in the range of less than 50 nm, preferably in the range ofF07417 20.10.2025281-20 nm, in particular in the range of 5-15 nm or 7-12 nm, and / or wherein the porous graphene layer 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%, and / or wherein 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, and essentially contiguous tungsten layer, preferably with 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, and by subsequently annealing at a pressure below normal pressure, preferably of less than 100 mTorr, 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 (2), wherein preferably 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 50-100 minutes, wherein preferably the catalytically inactive domains have an average characteristic width in the range of 10 - 100 nm, preferably in the range of 10-50 nm, or 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.

11. Method according to any of the preceding claims 8-10, wherein 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 graphene layer in situ being formed due to the presence of the catalytically inactive domains using methane gas as carbon source, preferably in the copresence 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, wherein 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, and / or wherein the porous graphene layer is removed from the catalytic substrate, and applied to a porous, preferably nonwoven or fabric supporting substrate, wherein the functionalization is carried out before or after the porous graphene layer has been detached from the catalytically active substrate and before or after being applied to said porous,F07417 20.10.202529 preferably nonwoven or fabric supporting substrate, preferably in that for removal of the graphene layer first a carrier layer is applied to the graphene layer on the surface opposite to the catalytic substrate and the sandwich of this carrier layer is removed from the catalytic substrate, wherein preferably prior to removal of the graphene layer, the layered structure of the catalytic substrate with the catalytically inactive domains and the graphene layer are subjected to a pre-leaching process weakening or removing the bond between the graphene layer and the catalytic substrate and / or wherein the catalytically inactive domains, wherein preferably this pre-leaching step includes the formation of an oxide layer at least partially, preferably essentially completely between the graphene layer and the catalytic substrate and the removal of the catalytically inactive domains, and / or wherein preferably the pre-leaching step is subjected to a basic or acidic environment, preferably in water, more preferably at a pH of less than 6 or more than 7, preferably more than 10, more preferably at a pH of more than 12, wherein most preferably an aqueous solution of 0.01-0.5 M NaOH is used, preferably for a time span in the range of 10-60 minutes at a temperature in the range of 40-60°C, optionally followed by rinsing with water and drying, or wherein 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, 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, 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 (5) from said catalytically active substrate, or wherein the graphene layer is removed, preferably after a pre-leaching step, using electrochemical methods, by immersing the layered structure of the catalytic substrate with the catalytically inactive domains and the graphene layer in an electrolyte and applying electrochemical potential to the substrate relative to a counterelectrode in the same electrolyte.

12. Method according to any of the preceding claims, wherein on the functionalized surface the silanization takes the form of a layer of individual orF07417 20.10.202530 interconnected filaments, and wherein the voids in that layer are or can be filled with a liquid, preferably a viscous liquid and / or a silicon oil.

13. Graphene layer, preferably on at least one supporting substrate, obtained using a method according to any of the preceding claims, wherein it 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 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% and / or wherein on the functionalized surface the silanization takes the form of a layer of individual or interconnected filaments, and wherein the voids in that layer are filled with a liquid, preferably a viscous liquid and / or a silicon oil.

14. Piece of textile or apparel having at least one graphene layer made using a method according to any of the preceding claims 1-12 and / or according to claim 13, preferably in the form of a filtering or separation device or a water resistant and / or water repellent and / or breathable apparel.

15. Use of a graphene layer according to any of the preceding claims as a membrane, preferably semipermeable membrane, in particular for filtering, separation or textile applications in the field of apparel, or for providing superhydrophobic or and / or slippery surface properties, including providing water barrier in electronics including batteries and / or mobile devices.

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