A terbium sulfide / graphene oxide composite modified electrode, a preparation method and application thereof, and an electrochemical device

Abstract

This invention belongs to the field of vanadium redox flow batteries, and relates to a terbium sulfide / graphene oxide composite modified electrode, its preparation method, application, and electrochemical device. The terbium sulfide / graphene oxide composite modified electrode comprises a carbon cloth substrate, graphene oxide supported on the surface of the carbon cloth substrate, and terbium sulfide nanoparticles grown in situ on the carbon cloth substrate and the surface of the graphene oxide. This invention synergistically constructs a three-dimensional porous composite electrode through the carbon cloth substrate, graphene oxide, and terbium sulfide nanoparticles, which has advantages such as large specific surface area, high electrocatalytic activity, and good structural stability. Graphene oxide forms a continuous conductive network on the carbon cloth surface, and terbium sulfide nanoparticles provide abundant catalytic active sites and are firmly bonded to the substrate. When applied to vanadium redox flow batteries, it can maintain high energy efficiency and voltage efficiency under high current density and long cycle conditions, while the electrode also has good flexibility, adapting to the needs of large-scale assembly.

Description

Technical Field

[0001] This invention relates to the field of vanadium redox flow battery technology, specifically to a terbium sulfide / graphene oxide composite modified electrode, its preparation method, application, and electrochemical device. Background Technology

[0002] As a large-scale energy storage technology, the performance of electrode materials in vanadium redox flow batteries directly affects the battery's energy efficiency, power density, and cycle stability. Carbon cloth, due to its flexibility, superior conductivity, and resistance to acid corrosion, is one of the most widely used electrode substrate materials in current vanadium redox flow batteries. However, unmodified carbon cloth has a low specific surface area and limited surface catalytic active sites, resulting in insufficient electrocatalytic activity for the redox reaction of vanadium ions, making it difficult to meet the performance requirements of electrodes for high current densities.

[0003] To improve the performance of carbon cloth electrodes, existing technologies often modify the carbon cloth. One typical approach is to use graphene oxide as a single modification. Graphene oxide has a two-dimensional sheet structure and a theoretically large specific surface area; introducing it into the carbon cloth system can improve the surface properties of the carbon cloth to some extent. However, carbon cloth electrodes obtained by modifying carbon cloth with graphene oxide alone still have the following shortcomings when practically applied in vanadium redox flow batteries: First, the specific surface area of ​​carbon cloth electrodes modified solely with graphene oxide has only a limited increase and remains at a relatively low level overall. Graphene oxide sheets tend to agglomerate or distribute unevenly on the carbon cloth fiber surface, resulting in a limited number of active sites on the electrode surface suitable for vanadium ion adsorption and reaction, thus restricting further improvement in the electrode's electrocatalytic performance.

[0004] Secondly, carbon cloth electrodes modified solely with graphene oxide exhibit poor structural stability. The interfacial bonding between the graphene oxide modified layer and the carbon cloth substrate is weak. During repeated charge-discharge cycles or electrode bending and assembly, the modified layer is prone to detachment or peeling, leading to irreversible damage to the electrode structure and severely limiting the electrode's cycle life.

[0005] Furthermore, the catalytic activity of carbon cloth electrodes modified solely with graphene oxide for the electrochemical reaction of vanadium ions is still insufficient, making it difficult to maintain high voltage efficiency and energy efficiency under high current density conditions.

[0006] Therefore, how to provide a modified carbon cloth electrode that combines high specific surface area, excellent electrocatalytic activity and high structural stability to meet the application requirements of vanadium redox flow batteries under high current density and long cycle conditions is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] (a) Technical problems to be solved To address the limitations of existing graphene oxide-modified carbon cloth electrodes in terms of limited specific surface area improvement, poor electrode structural stability, and insufficient electrocatalytic activity, this invention provides a terbium sulfide / graphene oxide composite modified electrode, its preparation method, application, and electrochemical device.

[0008] (II) Technical Solution To achieve the above objectives, the main technical solutions adopted by the present invention include: In a first aspect, the present invention provides a terbium sulfide / graphene oxide composite modified electrode, comprising a carbon cloth substrate, graphene oxide loaded on the surface of the carbon cloth substrate, and terbium sulfide nanoparticles grown in situ on the carbon cloth substrate and the surface of graphene oxide.

[0009] Secondly, the present invention provides a method for preparing the above-mentioned terbium sulfide / graphene oxide composite modified electrode, comprising the following steps: S1: The carbon cloth substrate is subjected to plasma treatment to obtain an activated carbon cloth substrate; S2: Provides a mixed dispersion containing terbium source, sulfur source, graphene oxide, dispersing and binding agent and perfluorosulfonic acid resin; S3: The activated carbon cloth substrate is placed in the mixed dispersion for impregnation treatment to obtain impregnated carbon cloth; S4: The impregnated carbon is arranged in a closed reactor and subjected to hydrothermal treatment under heating conditions, followed by washing and vacuum drying to obtain a terbium sulfide / graphene oxide composite modified electrode.

[0010] In the preparation method of the terbium sulfide / graphene oxide composite modified electrode as described above, optionally, in step S1, the plasma treatment is carried out under an argon atmosphere, with a treatment power of 50-120W and a treatment time of 5-15min.

[0011] In the preparation method of the terbium sulfide / graphene oxide composite modified electrode as described above, optionally, in step S2, the terbium source is a soluble terbium salt and its hydrate, and the sulfur source includes thiourea and sodium thiosulfate, with the mass ratio of thiourea to sodium thiosulfate being 1:1-3:1. The mixed dispersion was prepared as follows: terbium source and sulfur source were added sequentially to an aqueous solution with a pH of 3-4, stirred until completely dissolved, and then a dispersing and binding agent was added to obtain a dispersion. Then, graphene oxide and perfluorosulfonic acid resin were added and mixed evenly to obtain a mixed dispersion. The dispersing and binding agent was polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, or sodium carboxymethyl cellulose.

[0012] In the preparation method of the terbium sulfide / graphene oxide composite modified electrode as described above, optionally, in step S2, the concentration of the terbium source in the dispersion is 1-1.5 g / L, the concentration of the sulfur source is 15-20 g / L, the concentration of the dispersing and binding agent is 3-5 g / L, and the perfluorosulfonic acid resin is added in the form of a solution with a mass fraction of 3-10%, and the volume ratio of the perfluorosulfonic acid resin solution to the dispersion is 1:(300-800).

[0013] In the preparation method of the terbium sulfide / graphene oxide composite modified electrode as described above, optionally, in step S2, graphene oxide is added in the form of a dispersion with a concentration of 1-3 mg / mL, and the volume ratio of the added graphene oxide dispersion to the total dispersion is 1:(1000-2000).

[0014] In the preparation method of the terbium sulfide / graphene oxide composite modified electrode as described above, optionally, in step S3, the activated carbon cloth substrate is placed in a mixed dispersion, vacuumed to -0.06MPa~-0.1MPa and held at pressure for 10-20min, and then restored to normal pressure to complete one cycle; then the vacuuming, pressure holding and restoration to normal pressure cycle is repeated 2-4 times, and then the carbon cloth substrate is placed in a water bath at 50-70℃ for static impregnation for 1-3h to obtain impregnated carbon cloth.

[0015] In the preparation method of the terbium sulfide / graphene oxide composite modified electrode as described above, optionally, in step S4, impregnated carbon is arranged in a closed reactor, heated to 120-140℃ at a heating rate of 1-5℃ / min and held at that temperature for 8-12h, and then washed and vacuum dried to obtain the terbium sulfide / graphene oxide composite modified electrode.

[0016] Thirdly, the present invention provides an application of the above-mentioned terbium sulfide / graphene oxide composite modified electrode or the electrode prepared by the above-mentioned method for preparing the terbium sulfide / graphene oxide composite modified electrode in vanadium redox flow batteries, water electrolysis hydrogen production devices, air batteries, supercapacitors, zinc-bromine flow batteries or all-iron flow batteries.

[0017] Fourthly, the present invention also provides an electrochemical device comprising the above-described terbium sulfide / graphene oxide composite modified electrode or an electrode prepared by the above-described method for preparing the terbium sulfide / graphene oxide composite modified electrode. The electrochemical device is a vanadium redox flow battery, a water electrolysis hydrogen production device, an air battery, a supercapacitor, a zinc-bromine redox flow battery, or an iron redox flow battery.

[0018] (III) Beneficial Effects First, the composite modified electrode of this invention uses carbon cloth as a substrate. The carbon cloth is woven from fibers, and the interlacing of these fibers forms a large number of micron-sized pores, thus constituting a three-dimensional porous network framework. Graphene oxide is loaded onto the surface of the carbon cloth, appearing microscopically as slight protrusions extending along the carbon cloth fibers, thereby constructing a two-dimensional conductive reinforcement network on the three-dimensional framework of the carbon cloth. Terbium sulfide nanoparticles are anchored on the surfaces of the carbon cloth fibers and graphene oxide. The introduction of graphene oxide and terbium sulfide nanoparticles increases the roughness and effective specific surface area of ​​the carbon cloth electrode, providing abundant adsorption and active sites for the redox reaction of vanadium ions.

[0019] Secondly, in the composite modified electrode of the present invention, terbium sulfide nanoparticles are simultaneously anchored to the carbon cloth substrate and the graphene oxide surface through in-situ growth, so that a tight interfacial bond is formed between the carbon cloth substrate, the graphene oxide layer and the terbium sulfide active phase, which effectively enhances the adhesion between the modified layer and the carbon cloth substrate. During repeated charge-discharge cycles or electrode bending operations, the modified layer is not easy to fall off or peel off, the electrode structure remains intact, and the cycle life is significantly extended.

[0020] Third, the composite modified electrode of this invention uses in-situ grown terbium sulfide nanoparticles as the core electrocatalytic active phase. Terbium sulfide has an intrinsic catalytic promoting effect on the redox reaction of vanadium ions, which can effectively reduce the activation energy and overpotential of the reaction. The terbium sulfide nanoparticles are simultaneously distributed on the carbon cloth substrate and the surface of graphene oxide, making full use of the high specific surface area provided by graphene oxide, so that the catalytic active sites are fully exposed. The overall electrocatalytic activity of the electrode is significantly enhanced compared with the single graphene oxide modified carbon cloth electrode, so that the electrode can maintain excellent electrocatalytic response and energy efficiency at high current densities, effectively overcoming the shortcomings of the single graphene oxide modified electrode under high current density conditions.

[0021] Fourth, the composite modified electrode of this invention achieves a synergistic unity of high specific surface area, excellent conductivity, high structural stability, and high electrocatalytic activity through the structural coupling and functional complementarity of the carbon cloth substrate, graphene oxide, and terbium sulfide nanoparticles. When applied to vanadium redox flow batteries, it can maintain high energy efficiency and voltage efficiency under high current density and long cycle conditions. At the same time, the electrode has good flexibility and can adapt to the needs of large-scale and modular assembly. Attached Figure Description

[0022] Figure 1 A comparison diagram of the specific surface area of ​​the electrodes prepared in Example 1 and Comparative Examples 1-2; Figure 2 The efficiency-cycle results are shown in the graph for the electrode prepared in Example 1. Figure 3 Efficiency-cycle results of the electrode prepared for Comparative Example 1; Figure 4 Efficiency-cycle results for the electrode prepared in Comparative Example 2; Figure 5 The electrodes prepared for Example 1 and Comparative Examples 1-2 were subjected to an A·cm² temperature of 200 mA·cm². -2 Voltage efficiency-cycle stability curve at the specified value; Figure 6 This is a scanning electron microscope image of the electrode prepared in Example 1 at a low magnification. Figure 7 The image shows a scanning electron microscope image of the electrode prepared in Example 1 at a high magnification. Detailed Implementation

[0023] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] This invention provides a terbium sulfide / graphene oxide composite modified electrode, comprising a carbon cloth substrate, graphene oxide supported on the surface of the carbon cloth substrate, and terbium sulfide nanoparticles grown in situ on the carbon cloth substrate and the surface of graphene oxide.

[0025] In the terbium sulfide / graphene oxide composite modified electrode provided by this invention, the carbon cloth substrate serves as the macroscopic flexible support framework of the electrode. It is composed of interwoven fibers, giving the electrode a three-dimensional porous network structure that provides basic mechanical strength and electronic conduction channels. The carbon cloth is typically a commercially available polyacrylonitrile-based or viscose-based carbon fiber woven fabric, and its thickness and areal density can be selected according to actual application requirements. The inherent interwoven fiber structure of the carbon cloth endows the electrode with good flexibility and breathability, enabling it to adapt to the common compaction assembly process in vanadium redox flow battery stacks and maintain structural integrity under the scouring environment of electrolyte flow.

[0026] Graphene oxide is loaded onto the surface of carbon cloth fibers, specifically manifested as slight protrusions spreading along the fiber direction, forming a two-dimensional conductive reinforcement network. Graphene oxide sheets possess extremely high theoretical specific surface area and abundant oxygen-containing functional groups. When fully spread on the carbon cloth fiber surface, they not only significantly increase the geometric specific surface area and electrochemical active area of ​​the electrode, but also provide a rapid electron transport path through their conjugated π-electron system.

[0027] Terbium sulfide nanoparticles are simultaneously anchored on the surface of carbon cloth substrate fibers and graphene oxide sheets via in-situ growth, constituting the core electrocatalytic active phase of the electrode in this invention. As a rare-earth metal sulfide, terbium sulfide intrinsically promotes the vanadium ion redox couple in vanadium redox flow batteries, effectively reducing V2. 3+ / V 2+ and VO 2+ / VO2 +The activation barrier and overpotential of the redox reaction occurring on the electrode surface are crucial factors. More importantly, terbium sulfide nanoparticles are not attached to the electrode surface through physical coating or simple mechanical mixing, but rather through in-situ chemical reactions during hydrothermal processes, directly nucleating and growing at the solid-liquid interface of carbon cloth fibers and graphene oxide. This in-situ growth mode results in tight chemical bonds and mechanical interlocking between the terbium sulfide nanoparticles, the carbon cloth substrate, and the graphene oxide layer, significantly enhancing the interfacial bonding strength between the catalytic active layer and the conductive substrate. During long-term charge-discharge cycles, even under conditions of continuous electrolyte scouring and repeated electrode bending, the terbium sulfide nanoparticles are not prone to detachment, aggregation, or peeling, thus ensuring the long-term stability of the electrode active sites and the cycle life.

[0028] In the composite electrode of this invention, the three-dimensional porous framework of the carbon cloth substrate, the two-dimensional conductive network of graphene oxide, and the catalytically active phase of terbium sulfide nanoparticles are not simply physical superpositions, but rather form a highly efficient whole through structural coupling and functional complementarity. The carbon cloth provides a macroscopic conductive framework and flexible support, the graphene oxide constructs high-speed electron transport pathways at the microscale, and the terbium sulfide nanoparticles serve as highly active catalytic centers dispersed throughout the structure. Electrons can be rapidly transferred from the carbon cloth substrate to each terbium sulfide active site via the graphene oxide sheets, while vanadium ions can smoothly diffuse into the electrode interior through the inherent three-dimensional porous channels of the carbon cloth, thereby achieving synergistic optimization of electron transport and ion mass transfer within the electrode.

[0029] The present invention also provides a method for preparing the above-mentioned composite modified electrode, comprising the following steps: S1: The carbon cloth substrate is subjected to plasma treatment to obtain an activated carbon cloth substrate.

[0030] S2: Provides a mixed dispersion containing terbium source, sulfur source, graphene oxide, dispersing and binding agent and perfluorosulfonic acid resin.

[0031] S3: The activated carbon cloth substrate is placed in a mixed dispersion for impregnation treatment to obtain impregnated carbon cloth.

[0032] S4: The impregnated carbon is arranged in a closed reactor and subjected to hydrothermal treatment under heating conditions. Then, the mixed product is washed and vacuum dried to obtain a terbium sulfide / graphene oxide composite modified electrode.

[0033] In step S1 above, plasma treatment of the carbon cloth substrate aims to improve the chemical inertness of the carbon cloth fiber surface, increase surface active sites, and provide a favorable interfacial chemical environment for the uniform loading and firm anchoring of graphene oxide and terbium sulfide nanoparticles.

[0034] Commercially available carbon cloth typically contains small amounts of organic sizing agents, oil, and adsorbed impurities on its surface when it leaves the factory. These substances can hinder the direct contact between the modified components and the carbon fiber surface. Therefore, it is preferable to pre-treat the carbon cloth substrate by cleaning before plasma treatment. Specifically, carbon cloth cut to the required size can be ultrasonically cleaned sequentially in acetone, anhydrous ethanol, and deionized water for 10-20 minutes each to thoroughly remove surface organic contaminants and impurities. After cleaning, the carbon cloth should be placed in a vacuum oven and dried at 50-70°C for 4-8 hours to completely remove the moisture adsorbed on the fiber surface and within the pores, avoiding uneven local discharge caused by moisture evaporation during subsequent plasma treatment.

[0035] Plasma treatment is preferably performed under an argon atmosphere. Argon is a monatomic inert gas that is easily excited to form high-energy argon ions and free radicals under a radio frequency electric field. The cleaned and dried carbon is placed in the plasma treatment chamber. First, a vacuum is drawn until the background pressure is below 5 Pa to remove residual air from the chamber. Then, high-purity argon is introduced, with the gas flow rate adjusted to 30-50 sccm, maintaining the chamber pressure within the range of 20-40 Pa. The radio frequency power supply is turned on, and the processing power is set to 50-120 W for a processing time of 5-15 min. Under these conditions, the high-energy particles in the argon plasma bombard the carbon fiber surface, which physically etches the carbon fiber surface, increasing surface roughness and microscopic defects, thereby increasing the effective specific surface area of ​​the carbon cloth. On the other hand, high-energy particle bombardment causes the carbon-carbon bonds on the carbon fiber surface to break, forming a large number of dangling bonds and highly active sites. These active sites react rapidly with oxygen or water molecules when exposed to air or subsequent solution environments, introducing oxygen-containing polar functional groups such as hydroxyl, carboxyl, and carbonyl groups onto the carbon fiber surface, significantly improving the hydrophilicity and chemical modifiability of the carbon cloth surface.

[0036] The carbon cloth substrate treated with plasma exhibits significantly improved surface wettability and a greatly reduced contact angle with the subsequent mixing and dispersion, which facilitates the full penetration and uniform spreading of the mixing and dispersion on the carbon cloth fiber surface. Simultaneously, the oxygen-containing functional groups introduced onto the surface can act as anchoring points, forming hydrogen bonds or other chemical interactions with the oxygen-containing functional groups on the graphene oxide sheet surface and the dispersing and binding agents, thereby significantly enhancing the interfacial adhesion between the modified layer and the carbon cloth substrate. After treatment, the carbon cloth is cooled to room temperature under argon protection and should be used in subsequent steps as soon as possible to maintain its surface-activated state.

[0037] In step S2, the mixed dispersion serves as the precursor medium for the subsequent impregnation process. Its composition, concentration, and preparation method directly affect the dispersion uniformity of graphene oxide, the in-situ generation quality of terbium sulfide nanoparticles, and the overall performance of the final electrode.

[0038] Terbium sources are used to provide Tb during hydrothermal reactions.3+ Terbium ions serve as a metallic precursor for terbium sulfide (Tb₂S₃) nanoparticles. Preferably, the terbium source can be a soluble terbium salt or its hydrate, specifically, for example, terbium nitrate, terbium chloride, or terbium acetate, and more preferably, terbium nitrate hexahydrate. Terbium nitrate has high solubility and good dissociation in water, and nitrate ions are easily reduced or decomposed in a hydrothermal environment, thus avoiding the introduction of difficult-to-remove impurity anions into the final product.

[0039] The sulfur source is used to provide sulfur under hydrothermal conditions. 2- Ions, with Tb 3+ The reaction produces terbium sulfide precipitate. Preferably, the sulfur source includes a combination of thiourea and sodium thiosulfate. Thiourea, as a commonly used sulfur source precursor, can slowly hydrolyze in an acidic hydrothermal environment, releasing hydrogen sulfide or sulfur. 2- Its release rate is relatively controllable, which is conducive to the uniform formation and gradual growth of terbium sulfide crystal nuclei. Sodium thiosulfate can undergo a disproportionation reaction under acidic conditions to produce elemental sulfur and sulfite. Elemental sulfur can further react with reducing species to produce sulfur. 2- This provides a supplementary sulfur source for the formation of terbium sulfide. When thiourea and sodium thiosulfate are used in combination, they can synergistically provide a sulfur source at different stages of the hydrothermal reaction, allowing S... 2- The release curve is smoother, avoiding uneven grain size or impurity phase formation caused by local supersaturation. Preferably, the mass ratio of thiourea to sodium thiosulfate is 1:1-3:1. If the thiourea ratio is too low, S 2- If the release rate is too fast, it can easily lead to coarse grains or agglomeration. If the proportion of sodium thiosulfate is too low, the sulfur source supply will be insufficient, which may affect the yield and crystallinity of terbium sulfide.

[0040] The combined use of dispersing and bonding agents and perfluorosulfonic acid resin is one of the key aspects of the method of this invention. The two work together to solve the problem of agglomeration of graphene oxide sheets in solution and the problem of insufficient adhesion of modified layers on carbon cloth substrate.

[0041] The preferred dispersing and binding agent is polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, or sodium carboxymethyl cellulose. When dissolved in water, the dispersing and binding agent effectively prevents the graphene oxide sheets from approaching each other and recombinizing. Simultaneously, the dispersing and binding agent can form hydrogen bonds and other intermolecular interactions with the oxygen-containing functional groups on the graphene oxide surface, allowing the agent to adsorb onto the graphene oxide sheet surface and further enhancing dispersion stability.

[0042] Perfluorosulfonic acid resin is a perfluorosulfonic acid-type cation exchange polymer, with commercial products such as Nafion. Its molecule consists of a hydrophobic polytetrafluoroethylene backbone and hydrophilic sulfonic acid-terminated side chains, forming stable micelles or solutions in polar solvents. In the mixed dispersion of this invention, the sulfonic acid groups of the perfluorosulfonic acid resin provide electrostatic repulsion, further inhibiting the aggregation of graphene oxide sheets and forming a synergistic dispersion effect with dispersing and binding agents. More importantly, the perfluorosulfonic acid resin can construct ion conduction channels within the electrode; its sulfonic acid groups can promote the rapid transport of vanadium ions within the electrode, reducing the ion transport impedance at the electrode-electrolyte interface. Simultaneously, the excellent film-forming properties and chemical stability of the perfluorosulfonic acid resin help form a stable protective network on the electrode surface, enhancing the electrode's long-term corrosion resistance and structural retention in strongly acidic vanadium electrolytes.

[0043] The preferred method for preparing the mixed dispersion is as follows: First, measure deionized water and add a small amount of concentrated hydrochloric acid to adjust the pH of the solution to 3-4. Under magnetic stirring, add terbium source and sulfur source sequentially to the acidic aqueous solution, and continue stirring for 10-30 minutes until the solids are completely dissolved, obtaining a clear solution. Then, add the dispersing and binding agent to the solution. To accelerate dissolution, it is preferable to heat the solution in a water bath to 50-70°C and continue stirring for 30 minutes to 2 hours until the dispersing and binding agent is completely dissolved and the solution becomes a uniform, transparent, viscous liquid, at which point the dispersion is obtained.

[0044] Subsequently, graphene oxide is added to the above dispersion. Graphene oxide is preferably added in the form of a pre-prepared aqueous dispersion to avoid clumping and dispersion difficulties caused by directly adding dry graphene oxide powder. The concentration of the graphene oxide dispersion is preferably 1-3 mg / mL, and the volume ratio of the added graphene oxide dispersion to the aforementioned dispersion is preferably 1:1000-1:2000. Finally, a perfluorosulfonic acid resin solution is added to the solution. Perfluorosulfonic acid resin is preferably added in the form of a solution with a mass fraction of 3-10%, and the volume ratio of the perfluorosulfonic acid resin solution to the dispersion is preferably 1:300-1:800. The mixed solution is placed in an ultrasonic cleaner and ultrasonically stirred at room temperature for 20-40 minutes to allow the graphene oxide sheets to be fully exfoliated and uniformly dispersed under the combined action of the dispersing and binding agent and the perfluorosulfonic acid resin, ultimately obtaining a uniform, stable mixed dispersion without obvious precipitation or stratification.

[0045] Preferably, the concentration of the terbium source in the dispersion is 1-1.5 g / L, the total concentration of the sulfur source is 15-20 g / L, and the concentration of the dispersing and binding agent is 3-5 g / L. The concentrations of each component are optimized to generate uniformly sized and well-dispersed terbium sulfide nanoparticles in the subsequent hydrothermal steps, while ensuring sufficient dispersion of graphene oxide and uniform loading of the modified layer on the carbon cloth.

[0046] The combined use of dispersing and binding agents and perfluorosulfonic acid resin fundamentally solves the problem of discontinuous conductive networks commonly found in existing graphene oxide-modified electrodes. When only graphene oxide is used for modification, the lack of effective dispersion control methods leads to severe agglomeration and stacking of graphene oxide sheets on the carbon fiber surface, making it difficult to form a continuous and complete two-dimensional conductive network. This results in numerous breaks and blockages in the electron transport path within the electrode, significantly increasing charge transfer resistance and exacerbating electrochemical polarization during battery charging and discharging, causing significant losses in voltage and energy efficiency. In this invention, the dispersing and binding agents and perfluorosulfonic acid resin work together to promote stable suspension of graphene oxide sheets in a mixed dispersion, either as a single layer or with few layers. When the activated carbon cloth substrate is immersed in this mixed dispersion, the graphene oxide sheets can spread uniformly on the carbon fiber surface and, under the synergistic bridging effect of the dispersing and binding agents and perfluorosulfonic acid resin, overlap and interconnect with each other, ultimately constructing a continuous, complete, and low-defect two-dimensional high-speed electron transport network on the carbon fiber surface. The continuity and integrity of this conductive network are significantly better than those of a single graphene oxide modified electrode. Electrons can be rapidly transferred between graphene oxide sheets and between graphene oxide and carbon cloth substrate, greatly reducing the charge transfer resistance of the electrode. This effectively alleviates electrochemical polarization and lays a key conductive foundation for improving battery voltage efficiency and energy efficiency.

[0047] In step S3, the activated carbon cloth substrate is impregnated in a mixed dispersion to obtain impregnated carbon cloth. To ensure the mixed dispersion fully penetrates the internal pores of the carbon cloth fiber bundles and forms a uniform precursor liquid film on the surface of each carbon fiber filament, this invention preferably employs a vacuum-assisted impregnation process. The specific operation is preferably as follows: The activated carbon cloth substrate is completely immersed in a container filled with the mixed dispersion, ensuring that all parts of the carbon cloth are covered by the liquid. The container is placed in a vacuum dryer or vacuum chamber, sealed, and a vacuum pump is turned on to evacuate air, achieving a vacuum level of -0.06 MPa to -0.1 MPa. Under this vacuum condition, the gas originally occupied by air in the micropores and gaps inside the porous structure of the carbon cloth is extracted, creating a negative pressure environment. The vacuum state is maintained for 10-20 minutes, allowing the mixed dispersion to gradually penetrate into the internal pores of the carbon cloth fiber bundles and the micro-grooves on the fiber surface under the drive of the pressure difference. Subsequently, the vacuum is slowly released to restore the chamber to normal pressure, completing one cycle. At this time, the external atmospheric pressure will drive the liquid to further penetrate deeper into the carbon cloth. The above-mentioned vacuuming-pressure holding-restoration-normal pressure operation can be repeated 2-4 times to ensure that the precursor solution is filled and uniformly distributed in the three-dimensional structure of carbon cloth to the maximum extent.

[0048] After vacuum impregnation, the container containing the carbon cloth is transferred to a constant-temperature water bath and left to stand for 1-3 hours at 50-70℃. Moderate heating reduces the viscosity of the mixed dispersion, improves the mobility of the dispersing binder and perfluorosulfonic acid resin molecular chains, and promotes the adsorption and pre-assembly of graphene oxide sheets and terbium and sulfur precursor ions on the carbon fiber surface. After standing impregnation, the carbon cloth is removed from the mixed dispersion. At this point, sufficient mixed dispersion has been adsorbed onto the surface and internal pores of the carbon cloth, requiring no additional squeezing or rinsing. It can be directly used as impregnated carbon cloth for subsequent hydrothermal treatment steps.

[0049] Step S4 involves placing impregnated carbon in a closed reactor, such as a reaction vessel, and performing hydrothermal treatment under heating conditions to generate terbium sulfide nanoparticles in situ on the impregnated carbon cloth. Then, the carbon cloth is washed and vacuum dried to finally obtain a terbium sulfide / graphene oxide composite modified electrode.

[0050] Hydrothermal treatment is the core step in achieving in-situ growth of terbium sulfide nanoparticles and moderate reduction of graphene oxide. The impregnated carbon cloth is transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE). It should be noted that when the carbon cloth is removed from the impregnation solution, its surface and internal pores have already adsorbed a sufficient amount of the mixed dispersion. This liquid is carried into the reactor as a medium for the hydrothermal reaction, thus eliminating the need for additional liquid addition. After sealing the reactor, it is placed in an oven or muffle furnace and heated at a controlled rate. The preferred heating rate is 1-5 °C / min, more preferably 2 °C / min. Slow heating avoids localized overheating or sudden pressure increases within the reactor due to rapid heating, promoting uniform formation and gradual growth of terbium sulfide crystal nuclei, and preventing deformation or damage to the carbon cloth substrate due to thermal shock. The target temperature for hydrothermal treatment is preferably 120-140 °C, and the holding time is preferably 8-12 hours.

[0051] Under the aforementioned hydrothermal conditions, terbium ions adsorbed on the surface of carbon cloth in the mixed dispersion react with S produced by the decomposition of thiourea and sodium thiosulfate. 2- A chemical reaction occurs, resulting in the in-situ nucleation and growth of terbium sulfide nanoparticles on the surface of carbon fiber and graphene oxide sheets. Because the reaction occurs at the solid-liquid interface, and the polymer network formed by the dispersing binder and perfluorosulfonic acid resin has a confining and guiding effect on ion diffusion and grain growth, the generated terbium sulfide nanoparticles are small in size, uniformly dispersed, and form strong chemical bonds and physical interlocking with the carbon cloth substrate and the graphene oxide surface.

[0052] After hydrothermal treatment, allow the reactor to cool naturally to room temperature. Open the reactor and remove the carbon cloth sample. At this point, the surface of the carbon cloth may have a small amount of unreacted impurities or physically adsorbed ions attached. These need to be gently rinsed 2-4 times each with deionized water and anhydrous ethanol, alternating, to remove these residues. Vigorous rubbing or ultrasonication should be avoided during the cleaning process to prevent mechanical damage to the modified layer. After cleaning, place the carbon cloth in a vacuum oven and vacuum dry at 50-80℃ for 10-14 hours to obtain the final terbium sulfide / graphene oxide composite modified electrode.

[0053] The electrode prepared by this invention has a specific surface area of ​​up to 120 m². 2 / g or more. Electrode at 200mA·cm -2 The voltage efficiency at current density can reach over 88%, and the energy efficiency can reach over 86%. After 500 charge-discharge cycles, the voltage efficiency decay rate is less than 0.5%, demonstrating excellent comprehensive electrochemical performance and long-term cycle stability. The electrode also has good flexibility, and can be bent 100 times without significant damage. It is suitable for the large-scale and modular assembly requirements of vanadium redox flow batteries. At the same time, the preparation process is simple, environmentally friendly, and has a high yield, making it easy to promote and apply in industrial applications.

[0054] This invention also provides applications of the aforementioned terbium sulfide / graphene oxide composite modified electrode in vanadium redox flow batteries, water electrolysis hydrogen production devices, air batteries, supercapacitors, zinc-bromine flow batteries, or all-iron flow batteries. When used as the positive or negative electrode in a vanadium redox flow battery, this electrode can maintain a low polarization overpotential under high current density, significantly improving the battery's voltage efficiency and energy efficiency. Simultaneously, its excellent structural stability ensures the battery's performance retention during long-cycle charge-discharge processes. Furthermore, based on its high specific surface area, good conductivity, and the catalytic properties of terbium sulfide, this electrode can also be used as an electrode material in other electrochemical energy storage and energy conversion devices, such as in supercapacitors to improve specific capacitance and rate performance, in water electrolysis hydrogen production devices to catalyze hydrogen evolution or oxygen evolution reactions, or in the air electrode of a zinc-air battery to catalyze oxygen reduction and oxygen evolution reactions.

[0055] This invention also provides an electrochemical device comprising the aforementioned terbium sulfide / graphene oxide composite modified electrode. This electrochemical device can be a vanadium redox flow battery, a water electrolysis hydrogen production device, an air battery, a supercapacitor, a zinc-bromine flow battery, or an all-iron flow battery. The electrochemical device incorporating the electrode of this invention exhibits significant advantages over similar devices using traditional carbon cloth electrodes in terms of energy efficiency, power density, and cycle life due to the substantial improvement in electrode performance.

[0056] To further clarify the present invention and its technological advancements, the following description is provided in conjunction with specific embodiments and technical effects.

[0057] Example 1: This embodiment provides a method for preparing a terbium sulfide / graphene oxide composite modified electrode, including the following steps: S1: Commercial carbon cloth was cut into 2cm × 3cm rectangular pieces and ultrasonically cleaned sequentially in acetone, anhydrous ethanol, and deionized water for 15 minutes each. The cleaned carbon was then dried in a vacuum oven at 60℃ for 6 hours. The dried carbon was placed in a plasma treatment chamber, and a vacuum was drawn until the background pressure was below 5 Pa. High-purity argon gas was then introduced, with a flow rate of 40 sccm, maintaining the chamber pressure at 30 Pa. The radio frequency power supply was turned on, and the processing power was set to 80 W for 10 minutes. After treatment, the carbon cloth substrate was cooled to room temperature under argon protection to activate it, and then removed for later use.

[0058] S2: Measure deionized water, add concentrated hydrochloric acid dropwise to adjust the pH to 3.5, and add terbium nitrate, thiourea, and sodium thiosulfate sequentially under magnetic stirring. The mass ratio of thiourea to sodium thiosulfate is 2:1. Continue stirring for 20 minutes until the solids are completely dissolved, obtaining a clear solution. Next, add PVA with a molecular weight of 40,000, raise the water bath temperature to 60°C, and stir for 1 hour until the PVA is completely dissolved, resulting in a uniform, transparent, viscous liquid, obtaining a dispersion. Add a 2 mg / mL aqueous dispersion of graphene oxide to the dispersion, with a volume ratio of the aqueous dispersion of graphene oxide to the dispersion of 1:1500. Then add a 5% Nafion solution with a volume ratio of 1:500 to the dispersion, followed by ultrasonic stirring for 30 minutes to obtain a uniform mixed dispersion. In this step, the concentration of terbium source in the dispersion is 1.25 g / L, the total concentration of thiourea and sodium thiosulfate is 17.5 g / L, and the concentration of polyvinyl alcohol is 4 g / L.

[0059] S3: Completely immerse the activated carbon cloth substrate in the mixed dispersion. Place the beaker containing the mixed dispersion in a vacuum desiccator, evacuate to -0.08 MPa, maintain for 15 minutes, and then slowly release the vacuum. Repeat the evacuation-pressure holding-release process three times. Then seal the mouth of the beaker with plastic wrap and place it in a constant temperature water bath at 60℃ for 2 hours to soak.

[0060] S4: Transfer the impregnated carbon cloth to a polytetrafluoroethylene-lined high-pressure reactor, seal it, and place it in an oven. Heat the reactor to 130°C at a rate of 2°C / min and maintain the temperature for 8 hours. After the reaction, allow it to cool naturally to room temperature. Remove the carbon cloth and gently rinse it three times each with deionized water and anhydrous ethanol, alternating between the two. Then, dry the cleaned carbon cloth in a vacuum oven at 60°C for 12 hours to obtain... Figure 6 as well as Figure 7 The Tb2S3 / graphene oxide composite electrode shown. Figure 6The morphology at a lower magnification shows that the carbon cloth fibers are interwoven, forming abundant pores that constitute the three-dimensional porous skeleton of the electrode. Figure 7 After load modification, the carbon cloth fibers exhibited slight axially extending protrusions on their surface, which are graphene oxide. Simultaneously, in-situ grown terbium sulfide nanoparticles adhered to both the carbon cloth fibers and the graphene oxide. It can be seen that... Figure 6 and Figure 7 The loading of graphene oxide and terbium sulfide nanoparticles is relatively limited due to the low amount of precursor added during the preparation process. However, even so, the low loading is sufficient for the electrode in this embodiment to exhibit excellent electrochemical performance.

[0061] Example 2: This embodiment provides a method for preparing a terbium sulfide / graphene oxide composite modified electrode, including the following steps: S1: Commercial carbon cloth was cut into 2cm × 3cm rectangular pieces and ultrasonically cleaned sequentially in acetone, anhydrous ethanol, and deionized water for 10 minutes each. The cleaned carbon was then dried in a vacuum oven at 50℃ for 4 hours. The dried carbon was placed in a plasma treatment chamber, and a vacuum was drawn until the background pressure was below 5 Pa. High-purity argon gas was then introduced, with a flow rate of 30 sccm, maintaining the chamber pressure at 20 Pa. The radio frequency power supply was turned on, and the processing power was set to 50 W for 5 minutes. After treatment, the carbon cloth substrate was cooled to room temperature under argon protection to activate it, and then removed for later use.

[0062] S2: Measure deionized water, add concentrated hydrochloric acid dropwise to adjust the pH to 3, and add terbium nitrate, thiourea, and sodium thiosulfate sequentially under magnetic stirring. The mass ratio of thiourea to sodium thiosulfate is 1:1. Continue stirring for 10 minutes until the solids are completely dissolved to obtain a clear solution. Next, add polyvinylpyrrolidone (PVP) with a molecular weight of 39,000, raise the water bath temperature to 50°C, and stir for 0.5 hours until PPVP is completely dissolved, and the solution becomes a uniform, transparent, viscous liquid, obtaining a dispersion. Add a 1 mg / mL aqueous dispersion of graphene oxide to the dispersion, with a volume ratio of 1:1000. Then add a 3% Nafion solution with a volume ratio of 1:300 to the dispersion, followed by ultrasonic stirring for 20 minutes to obtain a uniform mixed dispersion. In this step, the concentration of terbium source in the dispersion is 1 g / L, the total concentration of thiourea and sodium thiosulfate is 15 g / L, and the concentration of polyvinylpyrrolidone is 3 g / L.

[0063] S3: Completely immerse the activated carbon cloth substrate in the mixed dispersion. Place the beaker containing the mixed dispersion in a vacuum desiccator, evacuate to -0.06 MPa, maintain for 10 minutes, and then slowly release the vacuum. Repeat the evacuation-pressure holding-release process twice. Then seal the mouth of the beaker with plastic wrap and place it in a constant temperature water bath at 50°C for 1 hour to soak.

[0064] S4: Transfer the impregnated carbon cloth to a high-pressure reactor lined with polytetrafluoroethylene (PTFE), seal it, and place it in an oven. Heat the reactor to 120°C at a rate of 1°C / min and maintain the temperature for 10 hours. After the reaction, allow it to cool naturally to room temperature. Remove the carbon cloth and gently rinse it twice each with deionized water and anhydrous ethanol, alternating between the two methods. Then, dry the cleaned carbon cloth in a vacuum oven at 50°C for 10 hours to obtain the Tb₂S₃ / graphene oxide composite electrode.

[0065] Example 3: This embodiment provides a method for preparing a terbium sulfide / graphene oxide composite modified electrode, including the following steps: S1: Commercial carbon cloth was cut into 2cm × 3cm rectangular pieces and ultrasonically cleaned sequentially in acetone, anhydrous ethanol, and deionized water for 20 minutes each. The cleaned carbon was then dried in a vacuum oven at 70℃ for 8 hours. The dried carbon was placed in a plasma treatment chamber, and a vacuum was drawn until the background pressure was below 5 Pa. High-purity argon gas was then introduced, with a flow rate of 50 sccm, maintaining the chamber pressure at 40 Pa. The radio frequency power supply was turned on, and the processing power was set to 120W for 15 minutes. After treatment, the carbon cloth substrate was cooled to room temperature under argon protection to activate it, and then removed for later use.

[0066] S2: Measure deionized water, add concentrated hydrochloric acid dropwise to adjust the pH to 4, and add terbium nitrate, thiourea, and sodium thiosulfate sequentially under magnetic stirring. The mass ratio of thiourea to sodium thiosulfate is 3:1. Continue stirring for 30 minutes until the solids are completely dissolved to obtain a clear solution. Next, add sodium carboxymethyl cellulose (molecular weight 41,000), raise the water bath temperature to 70°C, and stir for 2 hours until the sodium carboxymethyl cellulose is completely dissolved, and the solution becomes a uniform, transparent, viscous liquid to obtain a dispersion. Add a 3 mg / mL aqueous dispersion of graphene oxide to the dispersion, with a volume ratio of the aqueous dispersion of graphene oxide to the dispersion of 1:2000. Then add a 10% Nafion solution with a volume ratio of 1:800 to the dispersion, followed by ultrasonic stirring for 40 minutes to obtain a uniform mixed dispersion. In this step, the concentration of terbium source in the dispersion is 1.5 g / L, the total concentration of thiourea and sodium thiosulfate is 20 g / L, and the concentration of sodium carboxymethyl cellulose is 5 g / L.

[0067] S3: Completely immerse the activated carbon cloth substrate in the mixed dispersion. Place the beaker containing the mixed dispersion in a vacuum desiccator, apply a vacuum of -0.1 MPa, maintain the pressure for 20 minutes, and then slowly release the vacuum. Repeat the vacuum-pressure-release process four times. Then seal the mouth of the beaker with plastic wrap and place it in a constant temperature water bath at 70℃ for 3 hours to soak.

[0068] S4: Transfer the impregnated carbon cloth to a high-pressure reactor lined with polytetrafluoroethylene (PTFE), seal it, and place it in an oven. Heat the reactor to 140°C at a rate of 5°C / min and maintain the temperature for 12 hours. After the reaction, allow it to cool naturally to room temperature. Remove the carbon cloth and gently rinse it four times each with deionized water and anhydrous ethanol, alternating between the two. Then, dry the cleaned carbon cloth in a vacuum oven at 80°C for 14 hours to obtain the Tb₂S₃ / graphene oxide composite electrode.

[0069] Comparative Example 1: This comparative example provides a method for preparing a composite modified electrode. The difference from Example 1 is that the carbon cloth substrate is not subjected to plasma activation treatment in step S1.

[0070] Comparative Example 2: This comparative example provides a method for preparing a composite modified electrode. The difference from Example 1 is that PVA is not added in step S2, but the volume of Nafion solution added is twice the volume of Nafion solution in Example 1.

[0071] The specific surface area of ​​the electrode samples prepared in Examples 1-3 and Comparative Examples 1-2 was tested, and the results are as follows: Figure 1 As shown.

[0072] pass Figure 1 It can be seen that the specific surface area of ​​the terbium sulfide / graphene oxide composite modified electrode prepared in Example 1 reaches 128 m². 2 / g. Furthermore, testing showed that the specific surface areas of the electrodes prepared in Examples 2 and 3 were very close to those in Example 1, approximately 125 m². 2 / g and 127m 2 / g. The specific surface area values ​​of the three embodiments are all stable at a high level, indicating that the preparation method of the present invention can effectively construct a three-dimensional porous composite structure within different preferred parameter ranges, so that the graphene oxide is fully spread and the terbium sulfide nanoparticles are uniformly anchored, thereby significantly increasing the specific surface area of ​​the electrode.

[0073] In contrast, Comparative Example 1, lacking plasma activation pretreatment of the carbon cloth substrate, resulted in insufficient active sites on the carbon fiber surface and weak interfacial bonding between graphene oxide and the carbon cloth. This led to decreased uniformity and adhesion of the modified layer on the carbon cloth surface, reducing its specific surface area to 10³ m². 2 / g. In Comparative Example 2, without the addition of polyvinyl alcohol, dispersion was achieved solely through perfluorosulfonic acid resin. The graphene oxide sheets were prone to agglomeration in the solution, failing to form a continuous and uniform load on the carbon fiber surface, further reducing the electrode specific surface area to 90m². 2 / g. The above results indicate that plasma pretreatment and the introduction of the polyvinyl alcohol-perfluorosulfonic acid resin composite dispersion system are key factors in achieving uniform loading of graphene oxide and a significant increase in electrode specific surface area.

[0074] The electrodes prepared in Examples 1-3 and Comparative Examples 1-2 were used as the positive and negative electrodes of a vanadium redox flow battery, respectively, to assemble single cells. The cells were tested at 110-300 mA·cm⁻¹. -2 Constant current charge-discharge tests were performed at a current density, and the coulombic efficiency, voltage efficiency, and energy efficiency were recorded. The results are as follows: Figures 2 to 4 As shown.

[0075] pass Figure 2 It can be seen that the electrode prepared in Example 1 has a performance of 200 mA·cm⁻¹ -2 At the specified current density, the coulombic efficiency was 98.2%, the voltage efficiency was 88.4%, and the energy efficiency was 86.8%. Furthermore, the efficiency data of the electrodes prepared in Examples 2 and 3 were very close to those of Example 1. Specifically, the coulombic efficiency of the electrode in Example 2 was 98.0%, the voltage efficiency was 88.2%, and the energy efficiency was 86.5%, while the coulombic efficiency of the electrode in Example 3 was 98.3%, the voltage efficiency was 88.5%, and the energy efficiency was 87.0%. Examples 1-3 all exhibited high and stable coulombic efficiency, voltage efficiency, and energy efficiency under the same test conditions, proving that the method of the present invention can produce high-performance composite electrodes within different preferred parameter windows.

[0076] pass Figure 3 It can be seen that the electrode prepared in Comparative Example 1 operates at 200 mA·cm⁻¹. -2 At the specified current density, the coulombic efficiency was 96.8%, the voltage efficiency was 86.8%, and the energy efficiency was 84.1%. Compared with Example 1, the voltage efficiency and energy efficiency of Comparative Example 1 both decreased significantly. This is because the lack of a plasma activation step resulted in a stronger inertness on the carbon cloth surface, insufficient interfacial bonding between the modified layer and the carbon cloth substrate, leading to discontinuity in the electrode conductive network, decreased utilization of active sites, and increased electrochemical polarization.

[0077] pass Figure 4 It can be seen that the electrode prepared in Comparative Example 2 operates at 200 mA·cm⁻¹. -2At the specified current density, the coulombic efficiency was 97.4%, the voltage efficiency was 86.4%, and the energy efficiency was 84.1%. Compared with Example 1, the voltage efficiency of Comparative Example 2 decreased more significantly. This is because, without the addition of polyvinyl alcohol, the graphene oxide sheets agglomerated severely, making it impossible to form a continuous two-dimensional conductive network on the carbon fiber surface. This obstructed the electron transport path and increased the charge transfer resistance.

[0078] To further investigate the long-term operational stability of the electrodes, the electrodes prepared in Example 1 and Comparative Examples 1-2 were subjected to an operating temperature of 200 mA·cm⁻¹. -2 A continuous charge-discharge cycle test was conducted at a current density of 500 cycles, and the voltage efficiency was recorded as a function of the number of cycles. The results are as follows: Figure 5 As shown.

[0079] pass Figure 5 It can be seen that the electrode prepared in Example 1 maintained a highly stable voltage efficiency during 500 cycles, decreasing only from the initial 88.4% to 88.0%, with a decay rate of only 0.4%. In addition, the cycle stability of Examples 2 and 3 was found to be basically consistent with that of Example 1, with voltage efficiency decay rates of 0.5% and 0.4% after 500 cycles, respectively. All three exhibited excellent long-term cycle durability.

[0080] Comparative Example 1, lacking plasma activation, exhibited weak bonding between the modified layer and the carbon cloth substrate, leading to gradual detachment or peeling during cycling and a continuous decline in voltage efficiency. After 500 cycles, the voltage efficiency decay rate reached 5.4%. Comparative Example 2, without the addition of polyvinyl alcohol, suffered from severe graphene oxide agglomeration, resulting in even worse electrode structural stability. Its voltage efficiency showed a sharp decline after only 300 cycles, reaching a decay rate of 7.6%, failing to meet the electrode lifespan requirements for long-cycle energy storage applications.

[0081] Additionally, it should be noted that the amounts of graphene oxide and terbium sulfide precursors added in this invention have been optimized to achieve a significant performance improvement at lower loading levels, rather than pursuing higher loading levels. Therefore, in Figure 6 as well as Figure 7 In the scanning electron microscope images, graphene oxide appears as slight protrusions covering the surface of carbon fibers, and the distribution density of terbium sulfide nanoparticles is also relatively limited. However, even with a not particularly high loading, the composite electrode of this invention still exhibits a significantly improved specific surface area and excellent electrochemical performance, which further demonstrates the high efficiency of the composite structure constructed in this invention under the synergistic effect of its components.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A terbium sulfide / graphene oxide composite modified electrode, characterized in that, It includes a carbon cloth substrate, graphene oxide supported on the surface of the carbon cloth substrate, and terbium sulfide nanoparticles grown in situ on the carbon cloth substrate and the surface of graphene oxide.

2. A method for preparing the terbium sulfide / graphene oxide composite modified electrode according to claim 1, characterized in that, Includes the following steps: S1: The carbon cloth substrate is subjected to plasma treatment to obtain an activated carbon cloth substrate; S2: Provides a mixed dispersion containing terbium source, sulfur source, graphene oxide, dispersing and binding agent and perfluorosulfonic acid resin; S3: The activated carbon cloth substrate is placed in the mixed dispersion for impregnation treatment to obtain impregnated carbon cloth; S4: The impregnated carbon is arranged in a closed reactor and subjected to hydrothermal treatment under heating conditions, followed by washing and vacuum drying to obtain a terbium sulfide / graphene oxide composite modified electrode.

3. The method for preparing the terbium sulfide / graphene oxide composite modified electrode according to claim 2, characterized in that, In step S1, the plasma treatment is carried out under an argon atmosphere, with a treatment power of 50-120W and a treatment time of 5-15min.

4. The method for preparing the terbium sulfide / graphene oxide composite modified electrode according to claim 2, characterized in that, In step S2, the terbium source is a soluble terbium salt and its hydrate, and the sulfur source includes thiourea and sodium thiosulfate, with a mass ratio of thiourea to sodium thiosulfate of 1:1-3:

1. The mixed dispersion was prepared as follows: terbium source and sulfur source were added sequentially to an aqueous solution with a pH of 3-4, stirred until completely dissolved, and then a dispersing and binding agent was added to obtain a dispersion. Then, graphene oxide and perfluorosulfonic acid resin were added and mixed evenly to obtain a mixed dispersion. The dispersing and binding agent was polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, or sodium carboxymethyl cellulose.

5. The method for preparing the terbium sulfide / graphene oxide composite modified electrode according to claim 4, characterized in that, In step S2, the concentration of terbium source in the dispersion is 1-1.5 g / L, the concentration of sulfur source is 15-20 g / L, the concentration of dispersing and binding agent is 3-5 g / L, and perfluorosulfonic acid resin is added in the form of a solution with a mass fraction of 3-10%, and the volume ratio of perfluorosulfonic acid resin solution to dispersion is 1:(300-800).

6. The method for preparing the terbium sulfide / graphene oxide composite modified electrode according to claim 4, characterized in that, In step S2, graphene oxide is added in the form of a dispersion with a concentration of 1-3 mg / mL, and the volume ratio of the added graphene oxide dispersion to the total dispersion is 1:(1000-2000).

7. The method for preparing the terbium sulfide / graphene oxide composite modified electrode according to claim 2, characterized in that, In step S3, the activated carbon cloth substrate is placed in the mixed dispersion, vacuumed to -0.06MPa to -0.1MPa and held for 10-20 minutes, and then restored to normal pressure to complete one cycle; then repeat the vacuuming, holding and restoring to normal pressure cycle 2-4 times, and then place the carbon cloth substrate in a water bath at 50-70℃ for 1-3 hours to impregnate it to obtain impregnated carbon cloth.

8. The method for preparing the terbium sulfide / graphene oxide composite modified electrode according to claim 2, characterized in that, In step S4, the impregnated carbon is arranged in a closed reactor and heated to 120-140℃ at a heating rate of 1-5℃ / min and held at that temperature for 8-12h. Then, it is washed and vacuum dried to obtain the terbium sulfide / graphene oxide composite modified electrode.

9. The application of a terbium sulfide / graphene oxide composite modified electrode according to claim 1 or an electrode prepared by the preparation method of the terbium sulfide / graphene oxide composite modified electrode according to any one of claims 2-8 in a vanadium redox flow battery, a water electrolysis hydrogen production device, an air battery, a supercapacitor, a zinc-bromine flow battery, or an all-iron flow battery.

10. An electrochemical device, characterized in that, The electrode includes the terbium sulfide / graphene oxide composite modified electrode as described in claim 1, or the electrode prepared by the method for preparing the terbium sulfide / graphene oxide composite modified electrode as described in any one of claims 2-8. The electrochemical device is a vanadium redox flow battery, a water electrolysis hydrogen production device, an air battery, a supercapacitor, a zinc-bromine redox flow battery, or an iron redox flow battery.

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