Systems and methods for fabricating carbon nanotube-based electrodes

Abstract

Systems and methods are provided for preparing a graphene-based compound for fabricating electrodes.

Description

ANTONIJO LICITAR JANUARY 30, 2026P5889PC00SYSTEMS AND METHODS FOR FABRICATING CARBON NANOTUBE-BASED ELECTRODES

[0001] The present application claims the benefit of US provisional application 63 / 752,374 filed on January 31st, 2025.BACKGROUND

[0002] Textile waste, particularly cotton waste, is a global concern due to its environmental impact. Cotton, a natural fiber, is primarily composed of cellulose, a complex carbohydrate that forms the primary structural component of many plants. Cotton waste is generated in large quantities from various sources, including the textile industry, clothing manufacturing, and consumer discards. This waste often ends up in landfills or is incinerated, contributing to environmental pollution and waste of resources.

[0003] In addition, carbon nanomaterials, such as carbon nanotubes (CNTs) and graphene, are advanced materials with exceptional properties. Carbon nanotubes are cylindrical nanostructures composed of carbon atoms, exhibiting high strength, electrical conductivity, and thermal conductivity. Graphene, a single layer of carbon atoms arranged in a two-dimensional honeycomb lattice, is known for its exceptional mechanical strength, electrical conductivity, and thermal properties. These properties make carbon nanomaterials suitable for a wide range of applications, including electronics, energy storage, composite materials, and environmental remediation.

[0004] Furthermore, electrodes are a pivotal component in many electrochemical devices such as batteries, fuel cells, and supercapacitors. Traditional electrodes are often made from scarce or non-renewable resources, which can limit their efficiency and sustainability. Moreover, the fabrication of electrodes often involves high energy consumption and the use of hazardous chemicals, which poses environmental concerns.SUMMARY

[0005] According to one aspect of the present disclosure, a method for preparing a graphenebased compound for fabricating electrodes can include dispersing a waste material in an alkaline solution; mechanically processing the waste material and the alkaline solution to create a slurry; neutralizing the slurry with sulfuric acid; adding particles to the neutralized slurry; heating the neutralized slurry and iron particles to initiate a carbonization process, the carbonization process transforming fibers of the slurry into a compound comprising one or more graphene nanostructures; mixing the compound with clay to form a matrix comprising graphene, iron, and clay; and baking the matrix in an inert atmosphere.

[0006] In some embodiments, the waste can include at least one of cotton waste, cellulosic waste, wood waste, hemp, mushrooms, algae, or seaweed. In some embodiments, the alkaline solution can include a potassium hydroxide (KOH) solution. In some embodiments, the mechanical processing of the waste material and the alkaline solution can be performed using a blender. In some embodiments, heating the slurry to initiate the carbonization process can include heating the slurry in an atmosphere-controlled oven at a temperature between 400°C and 1200°C. In some embodiments, the atmosphere-controlled oven can be devoid of oxygen and comprises a controlled atmosphere of pure nitrogen (N) and carbon monoxide (CO).

[0007] In some embodiments, the baking can be performed at 1200°C. In some embodiments, the method can include electroplating the baked matrix with a layer of metal. In some embodiments, the metal can include nickel. In some embodiments, electroplating the baked matrix can include submerging the baked matrix in an electroplating bath. In some embodiments, the electroplating bath can include nickel sulfate (NiSO4), nickel chloride (NiCI2), boric acid (H3BO3), and water. In some embodiments, the electroplating bath comprises 240 g / L of NiSO4, 60 g / L of NiCI2, and 30 g / L of H3BO3. In some embodiments, electroplating the baked matrix can include passing a current through the electroplating bath.

[0008] In some embodiments, the method can include adding at least one transition metal catalyst into the matrix. In some embodiments, the at least one transition metal catalyst can include cobalt or nickel. In some embodiments, adding particles to the neutralized slurry can include adding at least one of iron, nickel, magnesium, silicon, aluminum, or a material salt to the neutralized slurry.

[0009] According to another aspect of the present disclosure, an electrode formed of a matrix that can include graphene, iron, and a ceramic-based material can be made by a process including the steps of dispersing a waste material in an alkaline solution; mechanically processing the waste material and the alkaline solution to create a slurry; neutralizing the slurrywith sulfuric acid; adding particles to the neutralized slurry; heating the neutralized slurry to initiate a carbonization process, the carbonization process transforming fibers of the slurry into a compound comprising one or more graphene nanostructures; mixing the compound with a ceramic-based material to form a matrix comprising graphene, iron, and the ceramic-based material; baking the matrix in an inert atmosphere; and electroplating the baked matrix with a layer of metal.

[0010] In some embodiments, the waste can include at least one of cotton waste, cellulosic waste, wood waste, hemp, mushrooms, algae, or seaweed. In some embodiments, the metal can include nickel. In some embodiments, electroplating the baked matrix can include submerging the baked matrix in an electroplating bath comprising nickel sulfate (NiSO4), nickel chloride (NiCI2), boric acid (H3BO3), and water.BRIEF DESCRIPTION OF THE FIGURES

[0011] FIG. 1 is a flowchart of an example process for producing CNTs from cotton waste according to example embodiments of the present disclosure.

[0012] FIG. 2A is a flowchart of an example process 200 for preparing a graphene-based compound for fabricating electrodes according to example embodiments of the present disclosure.

[0013] FIG. 2B is a flowchart of an example electroplating process 208 according to example embodiments of the present disclosure.

[0014] FIGS. 3A-3D show example Raman analysis performed on sample graphite collected according to various embodiments of the present disclosure.

[0015] The drawings are not necessarily to scale, or inclusive of all elements of a system, emphasis instead generally being placed upon illustrating the concepts, structures, and techniques sought to be protected herein.DETAILED DESCRIPTION

[0016] The following description sets forth exemplary aspects of the present disclosure. It should be recognized, however, that such description is not intended as a limitation on thescope of the present disclosure. Rather, the description also encompasses combinations and modifications to those exemplary aspects described herein.

[0017] The production of carbon nanomaterials typically involves high-temperature (between about 400°C and 1200°C) processes, such as carbonization or pyrolysis, in which carbon-containing materials are heated in the absence of oxygen. These processes can be applied to various carbon sources, including natural and synthetic polymers, hydrocarbons, and biomass. The choice of carbon source, along with the specific process conditions, can influence the properties and quality of the resulting carbon nanomaterials.

[0018] Various catalysts and support materials, such as iron (Fe), silicon (Si), and silicon dioxide (SiO2), can be used in the production of carbon nanotubes. These materials can influence the growth, structure, and properties of the carbon nanotubes. For instance, iron nanoparticles can facilitate the growth of carbon nanotubes and introduce magnetic properties, while silicon and silicon dioxide can serve as support materials and influence the carbonization process.

[0019] Despite the potential of carbon nanomaterials, their production often involves the use of non-renewable resources and energy-intensive processes. Therefore, there is a continuous interest in developing more sustainable and efficient methods for producing these advanced materials. These advanced carbon materials may include carbon nanotubes and graphene.

[0020] Embodiments of the present disclosure relate to systems and methods for producing CNTs. In particular, the disclosed systems and methods can convert waste materials, particularly textile waste such as cotton, into advanced carbon materials. In some embodiments, the disclosed principles involve a series of chemical and physical transformations of the waste material. This may include dispersion and saturation of the waste material in an alkaline solution, such as a potassium hydroxide (KOH) solution, followed by mechanical processing to create a fine slurry. The slurry may then be dried and re-saturated with a fresh alkaline solution. In some embodiments, the alkaline-treated waste material is subjected to high-temperature treatment in an atmosphere-controlled oven, inducing carbonization and transforming the waste material into a carbonaceous material comprising graphene monolayers.

[0021] Embodiments of the present disclosure can provide a sustainable and efficient way to produce advanced carbon materials from waste materials. By utilizing waste materials, particularly cotton waste, the disclosed techniques can not only provide a solution to waste management but can also reduce the environmental impact of waste. Furthermore, theadvanced carbon materials produced through this method may have enhanced properties and performance, potentially solving technical problems present in the field of advanced material production and application.

[0022] In additional embodiments, the resultant graphene fibers can be used as the base material for constructing 3D electrodes. These fibers can be mixed with clay to form a claygraphene matrix, which is then baked at a specific temperature in an inert atmosphere. In some embodiments, the baked clay-graphene electrodes are then electroplated with nickel, using a solution of nickel salts. This electroplating process can enhance the electrical conductivity and catalytic properties of the electrodes, making them suitable for various applications such as water electrolysis.

[0023] FIG. 1 is a flowchart of an example process 100 for producing carbon nanotubes from cotton waste according to example embodiments of the present disclosure. In some embodiments, the process 100 can begin with the collection of textile waste, particularly cotton waste or other waste primarily composed of cellulose. While the present disclosure primarily focuses on the use of cotton waste, it is worth noting that the method is not limited to this type of waste material. In some embodiments, fibers from various materials and waste material can be used in the production of carbon nanotubes and graphene. This can include, but is not limited to, feedstocks, cellulosic waste, wood waste, hemp, mushrooms, algae, seaweed, and other micro-structured materials with a high carbon content. In some embodiments, some polymers and plastics can be included, as well. Even waste materials with a high fat content can be used in the process. This flexibility in the choice of waste material broadens the applicability of the method and further contributes to waste management and environmental sustainability. In addition, it is important to note that various blocks listed in process 100 can be optional and only be used for specific applications. For example, in some embodiments, the slurry may not be dried.

[0024] At block 101, the process 100 can include dispersing the waste in an alkaline solution. In some embodiments, the alkaline solution can include a KOH solution, a sodium hydroxide (NaOH) solution, or other similar solutions. In some embodiments, an acid solution can be used instead of an alkaline solution. In some embodiments, the waste can be dispersed in the solution until saturation is reached. In some embodiments, the alkaline solution can be a one to six molar KOH solution. The dispersion and saturation of the cotton waste in the alkaline solution can facilitate the breakdown of the cellulose structure in the cotton fibers, which can better prepare them for subsequent carbonization. In some embodiments, the dispersing stepcan include immersing the waste in the KOH solution (e.g., a 12% KOH solution) for up to four hours, which can allow for the removal of non-cellulosic substances such as metals, dyes, and residual textile finishing chemicals.

[0025] At block 102, the process 100 can include mechanically processing the mixture to create a slurry of waste fibers and the alkaline material. The mechanical processing can involve various techniques and equipment. For example, in some embodiments, a blender can be used to mechanically process the saturated waste and alkaline material mixture. The use of a blender can allow for efficient and uniform processing of the cotton waste, resulting in a fine slurry of cotton fibers and the alkaline material. In some embodiments, various mixers (mechanical and ultrasonic) can be used, as well. In some embodiments, prior to mechanically processing the mixture, the process 100 can include scooping out an upper layer of the mixture to remove floating impurities.

[0026] At block 103, the process 100 can include drying the slurry to remove excess water. The drying process can involve various techniques and equipment, depending on the specific requirements and conditions. For instance, the slurry can be spread out on a flat surface and allowed to air dry, or it can be placed in a drying oven or a dehydrator. The goal of this drying process is to remove excess water from the slurry, leaving behind a dry mixture of cotton fibers and alkaline material. In some embodiments, prior to the drying, the shredded waste can be drained of excess KOH solution.

[0027] In some embodiments, prior to proceeding to block 104, the process 100 can include resaturating the dried slurry with another alkaline solution. This second solution can also include solutions of salts (e.g., Fe and Si). In one example, the dried slurry can be mixed with FeCI3solution, such as 50 ml of 3M FeCI3solution. This re-saturating can ensure complete contact of the cotton with the solution. In some embodiments, re-saturating the dried slurry can include adding a fresh KOH solution to the dried slurry and mixing it thoroughly. The re-saturation step can ensure thorough chemical penetration into the waste fibers, further preparing them for the subsequent carbonization process. The concentration of the fresh alkaline solution used for resaturation can vary, but in some cases, a one to six molar KOH solution can be used, similar to the initial dispersion step at block 101. In some embodiments, the resulting solution can be stirred with a magnetic stirrer, such as for about two hours and then dried again, such as in an oven overnight at a temperature of about 80°C.

[0028] At block 104, the process 100 can include heating the re-saturated slurry. In some embodiments, heating the re-saturated slurry can include placing the slurry in an atmosphere-controlled oven and heating it to a specific temperature in an environment devoid of oxygen. The absence of oxygen during this process may prevent combustion, allowing for the transformation of the cotton fibers into a carbonaceous material. The specific temperature for the carbonization process may vary, but in some embodiments, slurry can be heated to 400-1200°C (e.g., around 850°C), which can induce carbonization and lead to the formation of graphene and / or carbon nanotubes.

[0029] In some embodiments, the carbonization process at block 104 can be carried out in a controlled atmosphere of pure nitrogen, hydrogen, carbon monoxide, and / or argon. In some embodiments, the atmosphere can be a vacuum. In some embodiments, the atmosphere can include various noble gases and / or vapor from different materials such as magnesium, aluminum, etc. The use of these gases can provide an inert atmosphere, preventing oxidation and facilitating the carbonization process. The controlled atmosphere can also influence the structure and properties of the resulting carbon nanotubes. For instance, the presence of carbon monoxide may promote the formation of carbon nanotubes with a specific structure and size.

[0030] In some embodiments, the carbonization process at block 104 can include additional processing to produce graphene. This can include a second stage of carbonization, where the CNTs produced in the first stage are further processed through carbonization. This second stage of carbonization may lead to the transformation of the carbon nanotubes into graphene, a single layer of carbon atoms arranged in a two-dimensional honeycomb lattice. The specific conditions and parameters of this second stage of carbonization can be adjusted based on the specific requirements and desired properties of the resulting graphene. In some embodiments, the two-stage carbonization process can be performed as follows. First, the slurry can be heated up to about 350°C, such as at a heating rate of about 2.5°C / min. Then, the slurry can be held at 350°C for a predefined amount of time (i.e. , a “residence time”), which can be about one hour, to facilitate carbonization. The carbonization can be referred to as the first stage of the two-stage process. The second stage can be referred to as the graphitization process. Here, after the carbonization, the material can be heated to a temperature of about 900°C. In some embodiments, the heating rate for this heating phase can be the same as in the carbonization stage. Then, the mixture can be held at 900°C for another predefined period of time, such as one hour, to promote graphitization.

[0031] After the mixture has been held at 900°C and the graphitization has occurred, the mixture can be allowed to cool, for example at a slow cooling rate. At the end of the cooling, the graphitized cotton can be transferred to a beaker or other receptable and stirred with a solution.In some embodiments, the graphitized cotton can be stirred in an HCI solution, such as a 1M HCI solution. The stirring can be performed for about two hours or any other time necessary to assist with the removal of unwanted materials, such as residual iron and potassium species. In some embodiments, the stirring can also facilitate particle size reduction. In some embodiments, the stirring can also facilitate the reduction of particle size. In some embodiments, after the stirring has been completed, the solution of the graphitized cotton can be filtered and washed, such as with water and ethanol. The washing can be performed until a neutral pH is achieved. The material can then be filtered and dried before being collected for the desired application.

[0032] In some embodiments, other methods can be used after the first stage of the carbonization at block 104 to produce graphene. These methods can include, but are not limited to, collider or exfoliation techniques. Collider techniques can involve the use of high-energy collisions to break down the CNTs and rearrange the carbon atoms into a graphene structure. Exfoliation techniques, on the other hand, can involve the use of mechanical or chemical processes to separate the layers of the CNTs and form graphene. These alternative methods can provide additional flexibility in the production of graphene, allowing for the adjustment of the process based on the specific requirements and desired properties of the resulting graphene.

[0033] In some embodiments, the method can include the addition of different types of nanoparticles during the process 100, such as prior to the heating step at block 104. These nanoparticles can include, but are not limited to, nano iron (Fe) particles, nano carbon (C) graphite particles, magnesium (Mg) nanoparticles, copper (Cu) nanoparticles, cobalt, lithium (Li), aluminum (AL), zinc, titanium, platinum, nickel (Ni) nanoparticles, or combinations thereof. The incorporation of these nanoparticles into the carbon nanotubes can influence the properties and applications of the resulting carbon materials.

[0034] For instance, in some embodiments, nano Fe particles can be incorporated into the carbon nanotubes. The presence of Fe nanoparticles can introduce specific properties into the carbon nanotubes. These properties can include, but are not limited to, catalytic activity, magnetic properties, and enhanced adsorption capabilities for environmental remediation.

[0035] In some embodiments, nano C graphite particles or graphene can be incorporated into the carbon nanotubes. The addition of graphite nanoparticles to the carbon nanotubes can enhance their mechanical and thermal properties, making them suitable for various applications, such as reinforcement of materials and use as solid lubricants.

[0036] In some embodiments, Mg nanoparticles can be incorporated into the carbon nanotubes. Mg-decorated carbon nanotubes can be used for various applications, such as hydrogen storage in fuel cell applications and as catalysts in specific chemical reactions.

[0037] In some embodiments, Cu nanoparticles can be incorporated into the carbon nanotubes. Cu-decorated carbon nanotubes can enhance the electrical conductivity of materials, making them valuable in electronics and conductive coatings. They can also improve heat dissipation in electronic devices and thermal management applications.

[0038] In some embodiments, Ni nanoparticles can be incorporated into the carbon nanotubes. Ni-decorated carbon nanotubes can serve as catalysts for water splitting and hydrogen production. They can also be used in applications that require magnetic responsiveness.

[0039] In some embodiments, Silicon (Si) and silicon dioxide (SiO2) can also be used in the process 100. These materials generally serve as catalysts and as support materials in the conversion process. In addition, they can facilitate the decomposition of carbon-containing materials at high temperatures. Furthermore, Si and SiO2 can also influence the structure and properties of the resulting carbon nanotubes, potentially enhancing their performance in various applications by enhancing their electrical conductivity and increasing surface area.

[0040] As described above, Si and SiO2 can be used as support materials during the process. As support materials, they may provide a surface for the growth of carbon nanotubes, influencing their orientation and alignment. This can result in the formation of carbon nanotubes with a uniform and well-ordered structure, which can be beneficial for various applications, such as electronics and energy storage. Moreover, Si- or SiO2-decorated carbon nanotubes can exhibit improved electrical conductivity, making them suitable for use in high-performance electronic devices. They can also have a high surface area, making them effective for use in energy storage devices and environmental remediation applications.

[0041] It is important to note that the use of Si and SiO2 in the process 100 is not limited to the production of carbon nanotubes. In some embodiments, these materials can also be used in the production of other advanced carbon materials, such as graphene. The specific conditions and parameters of the process, including the concentration of Si and SiO2 and the carbonization temperature, can be adjusted based on the specific requirements and desired properties of the resulting carbon materials.

[0042] In some embodiments, using the assumption of a ten percent yield, the amount of carbon nanotubes produced from 1 kg of cotton waste can be as follows: 0.5 kg (500 grams) ofcarbon in cotton multiplied by 0.1 equals 50 grams of carbon nanotubes. Therefore, approximately 50 grams of carbon nanotubes can be obtained from one kg of cotton waste.

[0043] Embodiments of the present disclosure also relate to a process for preparing a graphene-based compound for fabricating electrodes. In particular, the disclosed method can yield graphene-based electrodes from renewable resources such as cotton waste. In other words, embodiments of the disclosure provide a method for transforming cotton waste into high-performance electrodes through a multi-step process involving chemical treatment, high-temperature carbonization, and electroplating. The disclosed method can offer an eco-friendly solution to electrode fabrication, leveraging the abundance of cotton waste and other renewable resources. For example, the disclosed techniques can include treating cotton waste with an alkaline solution, such as KOH, neutralizing the treated slurry with sulfuric acid (H2SO4), and incorporating iron (Fe) powder into the neutralized mixture. This mixture can then undergo a high-temperature carbonization process, resulting in graphene nanostructures embedded within a nano-porous Fe network. The resulting graphene-Fe compound can then be mixed with clay to form a matrix, which can be utilized to manufacture electrodes. In addition, the electrodes can be further enhanced with nickel electroplating.

[0044] The graphene-based electrodes fabricated via the disclosed techniques can demonstrate superior electrochemical properties, making them suitable for various industrial applications. For instance, the increased surface area and conductivity of these electrodes can improve hydrogen production efficiency in hydrogen electrolysis. In battery technology, the electrodes can enhance energy density and cycling stability, particularly in lithium-ion batteries. Furthermore, the electrodes can be applied to supercapacitors and wastewater treatment, exploiting their high surface area and electrocatalytic efficiency.

[0045] FIG. 2A is a flowchart of an example process 200 for preparing a graphene-based compound for fabricating electrodes according to example embodiments of the present disclosure. In some embodiments, the process 200 can begin with the collection of textile waste, particularly cotton waste or other waste primarily composed of cellulose. While the present disclosure primarily focuses on the use of cotton waste, it is worth noting that the method is not limited to this type of waste material. In some embodiments, fibers from various materials and waste material can be used in the production of carbon nanotubes and graphene. This can include, but is not limited to, feedstocks, cellulosic waste, wood waste, hemp, mushrooms, algae, seaweed, and other micro-structured materials with a high carbon content. Even waste materials with a high fat content can be used in the process. This flexibility in the choice ofwaste material broadens the applicability of the process and further contributes to waste management and environmental sustainability. In addition, it is important to note that various blocks listed in process 200 can be optional and only be used for specific applications. For example, in some embodiments, the slurry may not be dried. In another example, the neutralizing step may not be needed.

[0046] At block 201 , the process 200 can include dispersing the waste (or other material) in an alkaline solution. In some embodiments, the alkaline solution can include a KOH solution. In some embodiments, an acid solution can be used instead of an alkaline solution. In some embodiments, the waste can be dispersed in a one to six molar KOH solution, which forms a mixture. In some embodiments, the waste can be dispersed in the alkaline solution until saturation is reached. In some embodiments, similar to block 101 of FIG. 1, the dispersion and saturation of the waste in the solution can facilitate the breakdown of the cellulose structure in the cotton fibers, which can better prepare them for subsequent carbonization.

[0047] At block 202, the process 200 can include mechanically processing the mixture to form a fine slurry of waste fibers and alkaline material. The alkaline treatment may serve to modify the physical and chemical properties of the cotton waste, preparing it for subsequent processing steps. For example, the mechanical processing can involve various techniques and equipment. For example, in some embodiments, a blender can be used to mechanically process the saturated waste and alkaline material. The use of a blender can allow for efficient and uniform processing of the cotton waste, resulting in a fine slurry of cotton fibers and alkaline material. In some embodiments, various mixers (mechanical and ultrasonic) can be used, as well.

[0048] At block 203, the process 200 can include neutralizing the slurry. In some embodiments, the slurry can be neutralized with sulfuric acid (H2SO4). The neutralization step can result in the formation of potassium sulfate (K2SO4) and water (H2O). In addition, the neutralization step can serve to balance the pH of the slurry, ensuring that it is suitable for further processing.

[0049] At block 204, the process 200 can include adding particles to the neutralized slurry, in some embodiments, the particles can include Fe (e.g., Fe powder), nickel, silicon, magnesium, aluminum, material salts, and others. In some embodiments, the Fe powder can be micronsized, and its incorporation can serve to enhance the electrochemical properties of the resulting material. The Fe powder may be evenly distributed throughout the mixture, which can help ensure that the resulting material has a uniform composition.

[0050] At block 205, the process 200 can include heating the slurry and particle mixture. In some embodiments, heating the slurry and particle mixture can include initiating a high-temperature carbonization process, which can include heating the mixture from 400 to 1200°C (e.g., around 850°C) in a controlled atmosphere. For example, the controlled atmosphere can include pure nitrogen, carbon monoxide, and / or argon. In some embodiments, the atmosphere can be a vacuum. In some embodiments, the atmosphere can include various noble gases and / or vapor from different materials such as magnesium, aluminum, etc. The high-temperature carbonization process can result in the formation of graphene nanostructures embedded within a nanoporous Fe network.

[0051] In some embodiments, precise temperature control during the carbonization and electrode fabrication processes can be of operational relevance. For example, the temperature during this step can influence the quality and consistency of the graphene structure, as well as the electrochemical properties of the resulting electrodes. Therefore, maintaining a precise temperature during these processes can be beneficial for ensuring the production of high-quality graphene-based electrodes.

[0052] The high-temperature carbonization step of block 207 can be important in the fabrication of graphene-based electrodes. During this step, the mixture can be subjected to high temperatures in a controlled atmosphere, which can facilitate the transformation of the organic components of the mixture into carbon-based materials. The carbonization process can result in the formation of graphene nanostructures, which are single layers of carbon atoms arranged in a two-dimensional honeycomb lattice. The carbonization process can cause these graphene nanostructures to be embedded within a nanoporous Fe network, which forms a composite material with enhanced electrochemical properties.

[0053] In some embodiments, the number of graphene layers formed during the carbonization process may be optimized for specific applications. For instance, a greater number of graphene layers can be beneficial for applications that require high electrical conductivity, such as energy storage devices and sensors. On the other hand, a smaller number of graphene layers can be advantageous for applications that require high surface area, such as catalysts and adsorbents. The optimization of the number of graphene layers can be achieved by adjusting the carbonization conditions, such as the temperature, the duration, and the atmosphere. For example, a higher carbonization temperature or a longer carbonization duration can result in a greater number of graphene layers. Conversely, a lower carbonization temperature or a shorter carbonization duration can result in a smaller number of graphene layers. The atmosphereduring the carbonization process can also influence the number of graphene layers. For example, a nitrogen (N) and carbon monoxide (CO) atmosphere can facilitate the formation of a greater number of graphene layers.

[0054] At block 206, the process 200 can include mixing the heated compound (e.g., the carbonized compound) with a ceramic-based material, such as clay, zirconium, zeolites, yttrium, SiO2, aluminum oxide (AIO3), and others. In some embodiments, mixing the heated compound with ceramic-based material can yield a matrix. In some embodiments, the ceramic-based material can serve as a binder, helping to maintain the integrity and structure of the graphene-Fe compound. The matrix can then be utilized to manufacture electrodes, which may be used in various electrochemical devices. The electrodes fabricated from the matrix may demonstrate superior electrochemical properties, making them suitable for various industrial applications. In some embodiments, mixing the heated compound with ceramic-based material can also include mixing with water.

[0055] At block 207, the process 200 can include baking the compound (of graphene, Fe, clay, and / or water). In some embodiments, baking the compound can be performed at a high temperature, such as 1200°C, in an inert atmosphere. The high temperature can facilitate the formation of a stable matrix, while the inert atmosphere can prevent unwanted reactions that could compromise the quality of the matrix. The resulting matrix can exhibit a high degree of structural stability and electrical conductivity, making it suitable for the fabrication of electrodes.

[0056] At this point in process 200, after block 207 has been completed, the resulting compound (the matrix) can be utilized to manufacture electrodes. In some embodiments, the process of electrode fabrication can involve shaping the matrix into the desired form and applying a curing process to harden the electrode. The electrodes fabricated from the matrix can demonstrate superior electrochemical properties, such as high surface area, high electrical conductivity, and excellent electrocatalytic efficiency. These properties can make the electrodes suitable for various industrial applications, including but not limited to, hydrogen electrolysis, battery technology, and wastewater treatment.

[0057] In some embodiments, process 200 can further include an electroplating technique. For example, at block 208, the baked compound can be washed to prepare for electroplating. Then, at block 209, the process can include electroplating the baked compound from block 207. In some embodiments, the compound can be electroplated with nickel. Additional details of the disclosed electroplating techniques are described in relation to FIG. 2B. In some embodiments, after washing the material at block 208, the material can be neutralized again.

[0058] FIG. 2B is a flowchart of an example electroplating process 209 according to example embodiments of the present disclosure. At block 210, the process 209 can include submerging the graphene-clay electrodes in an electroplating bath. In some embodiments the electroplating bath can include nickel sulfate (NiSO4), nickel chloride (NiCI2), and boric acid (H3BO3). In some embodiments, the concentrations of the chemicals in the electroplating bath can be carefully controlled to ensure effective nickel deposition. For instance, the concentration of NiSO4can be around 240 g / L, the concentration of NiCI2can be around 60 g / L, and the concentration of H3BO3can be around 30 g / L. However, these concentrations can vary based on specific requirements. In some embodiments, the role of boric acid in the electroplating bath can be to buffer the pH and control the rate of nickel ion release, helping to ensure a uniform and high-quality nickel coating on the electrode surface. In some embodiments, during electroplating, the graphene-clay electrode can act as the cathode. When an electric current is applied, Ni2+ions in the solution can be reduced and deposited as a thin layer of metallic nickel on the electrode surface. Controlling the thickness and uniformity of the nickel layer can have important consequences for the electrode’s ultimate performance.

[0059] At block 211 , the process 209 can include passing an electric current through the solution. In some embodiments, passing the current through the solution can cause nickel ions to reduce and deposit on the surface of the electrodes. This can enhance the electrical conductivity and providing catalytic properties to the electrode. In some embodiments, the parameters of the nickel electroplating process, such as the current density, temperature, and plating time, can be carefully controlled and optimized for effective nickel deposition. For example, the current parameters can depend on the type of application and desired end product. In an example involving the intercalation of lithium, then a voltage of 3 V in voltage can be used. However, a value for other materials such as salts may include different values.

[0060] In some embodiments, the current density can range from around 2 to 4 A / dm2and the bath temperature can range from about 50-60°C.

[0061] For example, the optimization of these parameters can involve adjustments based on the specific properties of the electrodes and the desired characteristics of the nickel coating. In particular, a higher current density can result in a faster deposition rate, while a lower temperature can result in a smoother and more uniform coating. The plating time can be adjusted to control the thickness of the nickel layer, with a longer plating time resulting in a thicker layer. The optimization of these parameters can contribute to the production of high-quality electrodes with enhanced electrical conductivity and catalytic properties.

[0062] At block 212, the process 209 can include adding a transition metal catalyst to the solution. In some embodiments, the transition metal catalysts can include cobalt and / or nickel, in some embodiments, the incorporation of these catalysts can augment electrocatalytic effects and enhance the electrochemical activity of the graphene-based electrodes, potentially improving their performance in various electrochemical applications. In some embodiments, the type and amount of transition metal catalysts incorporated into the graphene matrix can be carefully controlled and optimized. The specific type of catalyst used can depend on the desired electrochemical properties of the resulting electrodes. For instance, cobalt can be used to enhance the electrocatalytic efficiency of the electrodes, while nickel can be used to enhance their electrical conductivity. The amount of catalyst incorporated can be adjusted based on the specific requirements of the electrochemical application.

[0063] In some embodiments, the incorporation of transition metal catalysts into the graphene matrix can involve a chemical reaction between the catalyst and the graphene nanostructures. This reaction can result in the formation of a stable and efficient metal-graphene composite material. The formation of this composite material can enhance the electrochemical properties of the resulting electrodes, making them suitable for various industrial applications.

[0064] In some embodiments, the graphene-based electrodes fabricated through the disclosed techniques can exhibit superior electrochemical properties, making them suitable for various industrial applications. The graphene nanostructures embedded within the nanoporous Fe network can provide a high surface area, which can enhance the electrochemical activity of the electrodes. The high surface area can facilitate the interaction between the electrode and the electrolyte in electrochemical devices, potentially improving the efficiency of the electrochemical reactions.

[0065] Other benefits can include high electrical conductivity and electrocatalytic efficiency. The high electrical conductivity can be attributed to the exceptional electronic properties of graphene and the conductive Fe network. The high electrical conductivity can enable efficient charge transfer in electrochemical devices, potentially improving their performance. The electrocatalytic efficiency can be particularly beneficial for applications such as hydrogen electrolysis and wastewater treatment, where the electrodes can facilitate the electrochemical reactions involved.

[0066] In addition, the disclosed electrodes can be used in various applications. For example, the graphene-based electrodes can be used in hydrogen electrolysis, where they can improve the efficiency of hydrogen production. The high surface area and electrocatalytic efficiency ofthe electrodes can enhance the rate of the water splitting reaction, potentially leading to a higher yield of hydrogen. In battery technology, the electrodes can enhance energy density and cycling stability, particularly in lithium-ion batteries. The high electrical conductivity and electrocatalytic efficiency of the electrodes can contribute to the improved performance of these batteries. In addition, the graphene-based electrodes can be applied to supercapacitors. The high surface area and electrical conductivity of the electrodes can enhance the charge storage capacity of the supercapacitors, potentially improving their energy storage performance. In environmental applications, such as wastewater treatment, the electrodes can exploit their high surface area and electrocatalytic efficiency to facilitate the removal of pollutants from wastewater.

[0067] Finally, the disclosed techniques (i.e., the processes of FIGS. 1, 2A, and 2B) can be extended to integrate other types of agricultural or industrial waste. This integration can further enhance the sustainability of the process, leveraging the abundance of these waste materials. The specific types of agricultural or industrial waste used can depend on various factors, including their availability, their chemical composition, and the desired properties of the resulting electrodes.

[0068] FIGS. 3A-3D show example Raman analysis performed on sample graphite collected according to various embodiments of the present disclosure. The Raman analysis was performed with Renishaw inVia™ confocal Raman microscope using green laser at 1% intensity to avoid burning of the measured materials. Four points were chosen at random from the material, and each plot 301-304 of FIGS. 3A-3D corresponds to one of those selected points, respectively. In the plots 301-304, the x-axis is wavelength in cm-1and the y-axis is intensity in abs. Table 1 below shows various parameters of interest of the plots 301-304.Table 1

[0069] Additional Applications

[0070] In some embodiments, the graphene materials produced according to the principles described herein can be used in applications that include 1) energy storage, such as supercapacitors and batteries where moderate surface areas can offer good conductivity and charge storage capabilities; 2) catalysis support, facilitating reactions without the need for extremely high surface areas; 3) electromagnetic shielding; 4) composite materials for enhancing mechanical strength and electrical conductivity; 5) sensors, such as gas or biosensors; and 6) heat dissipation.

[0071] Additional Features for Improving the Disclosed Principles

[0072] In some embodiments, using a higher ratio of KOH to cotton (e.g., 2:1 or more) can promote the development of more porous structures and increase surface area. In addition, both Fe and Ni can be incorporated as catalysts during the pyrolysis process, which can improve the formation of CNTs and graphene both enhancing both yield and conductivity. In some embodiments conducting the pyrolysis in an inert atmosphere (like argon) instead of air can prevent oxidation and improve graphitization, as well as increase crystallinity and conductivity. In some embodiments, post-annealing at 900-1000°C can improve the graphitic structure of the carbon material and can lead to better thermal stability and conductivity. In some embodiments, the mechanical milling process can be fine-tuned to reduce particle size and improve material properties. In some embodiments, introducing cryogenic milling (using liquid nitrogen) can prevent agglomeration during the milling process, which can help achieve a uniform nanoscale size distribution. In some embodiments, a ball-to-powder ratio of about 10:1 during milling can help achieve finer nanoparticles. In some embodiments, after milling, a mild acid wash (e.g., HCI) can remove residual metal catalysts, which can enhance conductivity and surface area. In some embodiments, after milling, functionalizing the CNTs or graphene with oxygen-containing groups or conductive coatings (e.g., graphene oxide or conductive polymers) can improve properties in battery and supercapacitor applications.

[0073] Example Cotton Preparation Methodology

[0074] An example cotton preparation methodology according to the present disclosure is as follows.

[0075] A first step involves preparing and blending the sample. The cotton sheets can be cut into small pieces (e.g., 1cm by 1cm) and soaked in a 6M KOH solution to remove impurities,dyes, etc. from the cotton. After the soaking, the released impurities can be collected from the top of the soaking container. Then, a portion of the mixture can be put into a blenderand blended continuously. In some embodiments, the levels of cotton and KOH solution can be approximately equal. During blending, the cotton threads can be separated from each other to enhance the swelling of the material. In some embodiments, the blender can be set to blend at its highest speed to add additional shredding. However, in some embodiments, the operating time of the blender has a maximum time of about 45 seconds.

[0076] A second step involves drying the samples. This step can include squeezing the mixture and then drying the mixture in a dryer, such as an industrial dryer. In some embodiments, the material can be dried for at least 1.5 hours.

[0077] A third step can involve preparing the samples for placement in a furnace. In some embodiments, water can be added to the container of cotton so that the water level is twice as high as the cotton level. Three balls can be placed in the container and ground for 30 minutes on a ball mill. In some embodiments, sulfuric acid can be added until a pH value around 3 is obtained. In some embodiments, iron can be added into the container, the amount depending on the specific application. In other embodiments, nickel can be added into the container, the amount depending on the specific application. The mixture can then be ground in the ball mill again to ensure the iron or nickel is evenly dispersed on the cotton. Then, the cotton can be separated from the liquid. In some embodiments, this can involve centrifuging the extracted liquid so that the iron or nickel settles at the bottom of the centrifuge tube. Thereafter, the process can be repeated one or more times and then inserted into the furnace.

[0078] A fourth step can involve placing the samples in the furnace. This can include placing the reactors and a fireclay brick in the furnace, as well as placing a requisite amount of granulated activated carbon onto the brick. This amount can be calculated by considering the inner furnace volume and the percentage of the oxygen present in the furnace. In some embodiments, 10g of granulated activated carbon can be enough.

[0079] In some embodiments, the furnace can be programmed to operate at 0-100 °C for 30 min; 100-100°C for 60 min; 100-600°C for 170 min; 600-850°C for 85 min; 850-850°C for 20 min; and 850-50°C for 300 min.

[0080] A fifth step can include thermal processing in the furnace. This can include vacuum pumping the furnace to obtain a complete or at least 80-90% vacuum and filling the furnace with nitrogen. Then, the material can be baked in the furnace.

[0081] Example Fe-Cotton and Ni-Cotton Materials Synthesis for Battery Electrodes

[0082] The preparation of the samples is as described elsewhere in this application, such as above in the example methodology for preparing cotton. For these preparation rounds, cotton waste can be cut into about 1cm x 1cm sizes, soaked in 2L of 6M KOH, blended with a blender, squeezed, dried, and acidified as described in an old document. Specific to these preparations, 4 jars (2 for Fe-cotton and the other 2 for Ni-cotton) were used. 90g of dried blended cotton waste was put in each of the jars. 500ml of distilled water was added into each jar. The jars were then transferred to the ball milling device for thorough mixing of the cotton and the waste for 30 minutes. After mixing, the pH of the content of each jar was measured, and based on this measurement, the acidification of the cotton solution was done. On average, 15ml of concentrated sulfuric acid was required to bring down the pH to the required value. To the two jars allocated to Fe-cotton, 180g of Fe was added into each of them, likewise 180g of Ni was added to each of the jars allocated to Ni-cotton. Each of the jars contained a total of 270g of Fe-cotton content and Ni-cotton content with respect to their allocations. Each jar was transferred to the ball milling device and allowed to mix for at least 2 hours. After mixing, the water was drained out of the jars, followed by drying and weighing each jar's contents.

[0083] In this example, recorded acidification pH values for the two Fe-cotton mixtures were 3.09 and 3.07. Moreover, recorded acidification pH values for the two Ni-cotton mixtures were 3.04 and 3.05. The total mass of material content in each jar (excluding water) was about 270g. the total mass of each jar after mixing, draining, and drying was 1) 242g (152g of Fe retained i.e. , 84% retained) for Fe-cotton mixture 1; 2) 248g (158g of Fe retained i.e., 88% retained) for Fe-cotton 2; 3) 250g (160g of Fe retained i.e., 89% retained) for Ni-cotton 1; and 4) 246g (154g of Fe retained i.e., 86% retained) for Ni-cotton 2.

[0084] Second Example Cotton Preparation Methodology and Resulting Yields

[0085] An example cotton preparation methodology according to the present disclosure is as follows.

[0086] The procedure is as outlined for the second attempt. The first step was the complete immersion of the cotton material in 12% KOH for the pretreatment of the cotton material to remove non-cellulosic substances such as metals, dyes, and residual textile finishing chemicals. This was left for 4 hours. After this immersion period, the upper layer was scooped out toremove floating impurities. The soaked cotton was then shredded with a blender to produce fibers. After the shredding, the shredded cotton was drained of excess KOH solution. It was then dried. 120g of the shredded cotton was then mixed with 240ml of 3M FeCI3solution to facilitate complete contact of the cotton with the ferric chloride solution, followed by 2hrs stirring using a magnetic stirrer. Then it was dried in the oven overnight at 80°C. The dried material was then transferred into a metal container and sealed. This container was then transferred into a furnace and was subjected to 2-stage pyrolysis. Firstly, it was heated up to 350°C at a heating rate of 3°C / min and was held for 1 hr (residence time) at 350°C to facilitate carbonization. After the carbonization, the graphitization was done by heating up the material to 900°C at the same heating rate and was held for 1 hr at 900°C to promote graphitization. At the end of the graphitization, the material cooled at a slower rate. At the end of the cooling, the graphitized cotton was transferred to a beaker and stirred in 2M HCI for 2 hrs. to remove unwanted materials such as residual iron and potassium species from the material and facilitate particle size reduction. After 2 hours, the solution of the graphitized cotton was neutralized with 0.1M KOH by adding dropwise and checking the pH. After attaining a neutral pH, the solution was filtered and washed several times with water and ethanol until neutral pH was confirmed. It was then transferred to an ethanol water solution that contains 20% ethanol in 500ml of water. It was then sonicated for 42 hours. Then transferred to magnetic stirrer for another 24hrs. The solution's upper layer was then filtered periodically with solvent added to make up for the reduced volume. This continued till the end of the duration. It was then filtered and dried, before transferring it into a muffle furnace for thermal treatment at 700 degrees for 3 hours. At the end of the treatment, the cotton graphene was collected, weighed, and stored for analysis.

[0087] Various different starting masses were utilized. In one embodiment, 120g of cotton yielded a 15.02g mass of graphene material (~12.51 %). In another embodiments, 100g of cotton yielded a 12.73g mass of graphene material.

[0088] Examples of Cotton Pyrolysis

[0089] An example of cotton pyrolysis according to the present disclosure is described as follows.

[0090] Here, the waste cotton material from fabrics was first cut to smaller pieces and immersed in a solution of 6M KOH for 3 hours. After this, the upper layer of the solution was scooped out to remove suspended contaminants, then the remaining was grinded with ablender to shred the cotton waste into threadlike materials as much as possible. This was followed by the pressing of the soaked blended cotton fiber to remove excess solvent before drying it in a vacuum dryer overnight. The dried cotton was then weighed into pyrolysis containers before transferring them into the furnace where previous furnace programming was followed by operating at a heating rate of 3°C / min up to 850°C, and a residence time of 20 minutes, in a nitrogen filled atmosphere. At the end of the pyrolysis, the material was extracted and weighed. A 52.4g mass of cotton fiber resulted in a 21 ,15g mass of cotton fiber after pyrolysis.

[0091] In an example where the cotton is heated to 900°C instead of 850°C and with a residence time of 120 minutes instead of 20 minutes, a 120.3g mass of cotton fiber resulted in a 36.07g mass of cotton fiber after pyrolysis.

[0092] Finally, 40g of cotton char carbonized at 350°C under inert atmosphere was mixed with KOH and FeCI3 in a ratio of 1 :2:0.5 (that is, KOH was twice the mass of cotton char, and FeCI3 was half the mass of the char). The materials were well mixed and weighed into pyrolysis container before transferring it into the furnace where the furnace was programmed at a heating rate of 3°C / min up to 900°C, and a residence time of 120 minutes, in a nitrogen filled atmosphere. At the end of the pyrolysis, the material was extracted and weighed. An 138g mass of loaded material resulted in 5.3g of product after pyrolysis.

[0093] In another example, 40g of carbonized cotton was weighed and mixed with 80g of KOH. They were blended using a coffee seed blending machine. After the blending, the material was transferred into the pyrolysis container. The container was then placed in the furnace where previous furnace programming was followed by operating at a heating rate of 3°C / min but to 900°C (instead of 850°C) and a residence time of 120 minutes (instead of 20 minutes), in a nitrogen filled atmosphere. At the end of the pyrolysis, the material was extracted and weighed. An 120g mass of loaded material resulted in 3.02g of product after pyrolysis.

[0094] While various embodiments have been described above, it should be understood that they have been presented by way of example and not limitation. It will be apparent to persons skilled in the relevant art(s) that various changes in form and detail may be made therein without departing from the spirit and scope. In fact, after reading the above description, it will be apparent to one skilled in the relevant art(s) how to implement alternative embodiments. For example, other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Accordingly, other implementations are within the scope of the following claims.

[0095] In addition, it should be understood that any figures which highlight the functionality and advantages are presented for example purposes only. The disclosed methodology and system are each sufficiently flexible and configurable such that they may be utilized in ways other than that shown.

[0096] Although the term “at least one” may often be used in the specification, claims and drawings, the terms “a”, “an”, “the”, “said”, etc. also signify “at least one” or “the at least one” in the specification, claims and drawings.

[0097] Finally, it is the applicant's intent that only claims that include the express language "means for" or "step for" be interpreted under 35 U.S.C. 112(f). Claims that do not expressly include the phrase "means for" or "step for" are not to be interpreted under 35 U.S.C. 112(f).

Claims

CLAIMS1. A method for preparing a graphene-based compound for fabricating electrodes comprising:dispersing a waste material in an alkaline solution;mechanically processing the waste material and the alkaline solution to create a slurry; neutralizing the slurry with sulfuric acid;adding particles to the neutralized slurry;heating the neutralized slurry and iron particles to initiate a carbonization process, the carbonization process transforming fibers of the slurry into a compound comprising one or more graphene nanostructures;mixing the compound with clay to form a matrix comprising graphene, iron, and clay; andbaking the matrix in an inert atmosphere.

2. The method of claim 1 , wherein the waste comprises at least one of cotton waste, cellulosic waste, wood waste, hemp, mushrooms, algae, or seaweed.

3. The method of claim 1 or 2, wherein the alkaline solution comprises a potassium hydroxide (KOH) solution.

4. The method of any of claims 1 - 3, wherein the mechanical processing of the waste material and the alkaline solution is performed using a blender.

5. The method of any of claims 1 - 4, wherein heating the slurry to initiate the carbonization process comprises heating the slurry in an atmosphere-controlled oven at a temperature between 400°C and 1200°C.

6. The method of claim 5, wherein the atmosphere-controlled oven is devoid of oxygen and comprises a controlled atmosphere of pure nitrogen (N) and carbon monoxide (CO).

7. The method of any of claims 1 - 6, wherein the baking is performed at 1200°C.

238. The method of any of claims 1 - 7, further comprising electroplating the baked matrix with a layer of metal.

9. The method of claim 8, wherein the metal comprises nickel.

10. The method of claim 8 or 9, wherein electroplating the baked matrix comprises submerging the baked matrix in an electroplating bath.

11. The method of claim 10, wherein the electroplating bath comprises nickel sulfate (NiSO4), nickel chloride (NiCI2), boric acid (H3BO3), and water.

12. The method of claim 11, wherein the electroplating bath comprises 240 g / L of NiSO4, 60 g / L of NiCI2, and 30 g / L of H3BO3.

13. The method of any of claims 10 - 12, wherein electroplating the baked matrix comprises passing a current through the electroplating bath.

14. The method of any of claims 1 - 13, comprising adding at least one transition metal catalyst into the matrix.

15. The method of claim 14, wherein the at least one transition metal catalyst comprises cobalt or nickel.

16. The method of any of claims 1 - 15, wherein adding particles to the neutralized slurry comprises adding at least one of iron, nickel, magnesium, silicon, aluminum, or a material salt to the neutralized slurry.

17. An electrode formed of a matrix comprising graphene, iron, and a ceramic-based material made by a process according to any of claims 1 - 16.

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