RuO2 / C functionalized composite material and preparation method and application thereof

Abstract

The invention belongs to a functional composite material, and provides a RuO2 / C functional composite material as well as a preparation method and application thereof in order to solve the technical problem of low CO2 conversion efficiency of a thermoelectric catalyst of an existing CO2 / H2 fuel cell cathode. The RuO2 / C functionalized composite material comprises carbon spheres, RuO2 particles are attached to the surfaces of the carbon spheres, the surfaces of the RuO2 particles are coated with carbon layers, and unpaired electrons exist on the surfaces of the carbon layers and the surfaces of the carbon spheres. According to the composite material disclosed by the invention, the surfaces of the carbon layer and the carbon spheres have rich unpaired electrons, and CO2 can be effectively adsorbed and activated in a specific CO2 / H2 fuel cell thermal field environment.

Description

Technical Field

[0001] This application pertains to a functional composite material, specifically relating to a RuO2 / C functionalized composite material, its preparation method, and its applications. Background Technology

[0002] Large-scale CO2 emissions have triggered a series of ecological and environmental problems. Reducing CO2 chemically (CO2R) to achieve carbon emission reduction can not only mitigate the greenhouse effect but also contribute to the recycling of carbon resources. Furthermore, improving energy efficiency is also a crucial pathway to carbon emission reduction.

[0003] Currently, chemical plants, cement plants, and steel mills all emit large amounts of CO2 and generate significant amounts of low-quality waste heat. Therefore, achieving low-temperature waste heat recovery is of great significance to enterprise development. A CO2 / H2 fuel cell is a device that can directly convert low-quality waste heat into electrical energy while selectively reducing CO2 gas into high-value-added chemicals such as methane. In this type of battery system, the anode undergoes a hydrogenation reaction, while the cathode undergoes a CO2 reduction reaction. However, the slow kinetics of the cathode CO2 reduction process, with its low conversion rate and efficiency, greatly restricts the further development of this technology. Currently, the core challenge of this technology lies in finding an efficient and stable thermoelectric catalyst for the cathode CO2 reduction reaction.

[0004] In existing technologies, researchers have explored various catalysts, such as noble metal catalysts (e.g., Pt) and ordinary RuO2 / C catalysts. However, noble metal catalysts exhibit poor selectivity for CO2 reduction and are prone to hydrogen evolution side reactions, resulting in low CO2 conversion efficiency. While ordinary RuO2 / C catalysts have applications in areas such as oxygen evolution reactions, their activity for CO2 reduction is not ideal when used in CO2 / H2 fuel cells, failing to achieve high CO2 conversion efficiency. Summary of the Invention

[0005] This application addresses the technical problem of low CO2 conversion efficiency in existing thermoelectric catalysts for CO2 / H2 fuel cell cathodes by providing a RuO2 / C functionalized composite material, its preparation method, and its application.

[0006] To achieve the above objectives, this application adopts the following technical solution: In a first aspect, this application proposes a RuO2 / C functionalized composite material, comprising carbon spheres; RuO2 particles are attached to the surface of the carbon spheres, and a carbon layer is coated on the surface of the RuO2 particles, wherein both the carbon layer and the surface of the carbon spheres have unpaired electrons.

[0007] Furthermore, RuO2 accounts for 1%-80% of the mass of RuO2 / C functionalized composite materials.

[0008] Furthermore, RuO2 accounts for 50%-80% of the mass of RuO2 / C functionalized composite materials.

[0009] Furthermore, the RuO2 particles are nanoparticles with a size of 1nm-10nm.

[0010] Secondly, this application proposes an application of the above-mentioned RuO2 / C functionalized composite material in the cathode thermoelectric catalyst of a CO2 / H2 fuel cell.

[0011] Furthermore, the CO2 / H2 fuel cell includes an anode, a cathode, an electrolyte membrane, and a reactant gas; The electrolyte membrane is an acidic electrolyte membrane containing phosphoric acid as an electrolyte; The reactant gases include H2 or a mixture of H2 and an inert gas introduced at the anode, and CO2 or a mixture of CO2 and an inert gas introduced at the cathode.

[0012] Thirdly, this application proposes a method for preparing the above-mentioned RuO2 / C functionalized composite material, comprising: The carbon precursor was added to deionized water and stirred until homogeneous to obtain a dispersion. Add RuO2 particles to the dispersion and stir until homogeneous to obtain a mixed solution; The mixed solution is subjected to a hydrothermal reaction at a first temperature. After the reaction is completed, it is cooled to room temperature, and the solid portion is dried at a second temperature to obtain a dried sample. The first temperature is greater than the second temperature. The dried sample was ground to obtain a RuO2 / C functionalized composite material.

[0013] Furthermore, the carbon precursor is at least one of glucose and sucrose.

[0014] Furthermore, the first temperature is less than or equal to 260°C.

[0015] Furthermore, the second temperature is 60℃-100℃.

[0016] Compared with the prior art, this application has the following beneficial effects: This application proposes a RuO2 / C functionalized composite material. The carbon layer and carbon spheres possess abundant unpaired electrons, which, under specific CO2 / H2 fuel cell thermal environments, can effectively adsorb and activate CO2. This causes the C=O double bonds of the highly stable CO2 molecule to bend and elongate, thus activating it. The unpaired electrons in the composite material are effectively transferred to Ru metal sites and oxygen sites, making both Ru and O reactive sites, effectively adsorbing and activating CO2. This mechanism overturns the commonly held belief that the metal center in oxide systems is the active site, and this effect cannot be achieved using RuO2 or carbon materials alone, or even other known catalysts. Experimental verification shows that the cathode using the RuO2 / C functionalized composite material of this application achieves a CO2-to-methane rate of 1242.5 μmol gcat. - ¹ h - ¹, which is 18 times that of RuO2 loaded on carbon nanotubes (RuO2 / CNTs), and the current contribution of methane generation is 28.2% (1.5% for RuO2 / CNTs), resulting in a significant improvement in performance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram illustrating the preparation principle of Example 1 of this application; Figure 2 This is a SEM image of the RuO2 / C functionalized composite material prepared in Example 1 of this application; Figure 3 This is a TEM image of the RuO2 / C functionalized composite material prepared in Example 1 of this application; Figure 4 Fourier transform infrared spectrum of the RuO2 / C functionalized composite material prepared in Example 1 of this application; Figure 5 The electron paramagnetic resonance spectrum of the RuO2 / C functionalized composite material prepared in Example 1 of this application; Figure 6 The diagram shows the methane production from CO2 reduction using the RuO2 / C functionalized composite material prepared in Example 1 of this application; wherein the reaction area of ​​the CO2 / H2 fuel cell electrode plate used is 9 square centimeters. Figure 7The diagram shows the methane production from CO2 reduction using the RuO2 / C functionalized composite material prepared in Example 1 of this application; wherein the reaction area of ​​the CO2 / H2 fuel cell electrode plate used is 24.6 square centimeters. Figure 8 The discharge curve of the RuO2 / C functionalized composite material prepared in Example 1 of this application for CO2 reduction is shown. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] In the description of the embodiments of this application, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0024] In the description of the embodiments of this application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0025] The greenhouse effect and extreme weather events caused by massive carbon dioxide emissions are becoming increasingly severe, making carbon emission reduction and carbon resource recycling a global consensus. Among numerous carbon emission reduction technologies, the CO2 reduction reaction (CO2R), as a chemical conversion pathway, can both reduce atmospheric CO2 concentration to mitigate the greenhouse effect and convert CO2 into high-value-added chemicals, achieving sustainable utilization of carbon resources, thus attracting widespread attention. Meanwhile, improving energy efficiency is also a key direction for carbon emission reduction. In industrial production, chemical plants, cement plants, steel mills, and other industries not only continuously emit large amounts of CO2 during production but also generate a large amount of underutilized, low-quality waste heat. Effective recovery of this waste heat can reduce enterprise energy consumption and further contribute to achieving carbon emission reduction targets. Against this backdrop, carbon dioxide / hydrogen fuel cells have emerged. These cells can directly convert low-quality waste heat into electrical energy, while simultaneously achieving highly selective reduction of CO2 at the cathode to produce economically valuable chemicals such as methane. The working principle involves a hydrogen oxidation reaction at the anode (hydrogen combines with oxygen to produce water and release electrons), and a CO2 reduction reaction at the cathode. This is a novel low-carbon technology that integrates waste heat recovery, power generation, and carbon conversion, and has broad application prospects in areas such as industrial emission reduction and distributed energy supply.

[0026] However, CO2 / H2 fuel cells still face core technological bottlenecks in practical applications. The kinetics of the CO2 reduction reaction at the cathode are extremely slow, and CO2 molecules struggle to undergo rapid electron transfer and chemical bond reconstruction on the cathode surface. This results in a consistently low CO2 conversion rate, causing the overall energy conversion efficiency and carbon conversion efficiency of the battery system to fail to meet the practical requirements of industrial applications. The key to solving this problem lies in developing high-performance thermoelectric catalysts for the CO2 reduction reaction at the cathode. The performance of these catalysts directly determines the overall technical specifications and application value of CO2 / H2 fuel cells.

[0027] To overcome the aforementioned technical bottlenecks, the scientific community has conducted extensive research on cathode catalysts for CO2 / H2 fuel cells, exploring various types of catalytic materials. Among these, noble metal catalysts were one of the earliest research directions. These materials have already demonstrated certain activity in the catalytic reactions of traditional fuel cells, and therefore are being explored for application in CO2 reduction reactions. In addition, ordinary ruthenium oxide / carbon catalysts have also attracted attention. These catalysts have a mature application foundation in scenarios such as the oxygen evolution reaction, and their structural characteristics are considered potentially suitable for CO2 reduction reaction systems.

[0028] However, existing catalyst solutions all have significant drawbacks, failing to fundamentally solve the problem of insufficient cathode catalytic efficiency in CO2 / H2 fuel cells. For noble metal catalysts, the core issue lies in their poor selectivity for the CO2 reduction reaction. While catalyzing CO2 reduction, they readily trigger hydrogen evolution side reactions, consuming electrons and energy in the battery and significantly reducing the effective CO2 conversion efficiency. Furthermore, the high cost of noble metal materials limits their feasibility for large-scale application. While ordinary RuO2 / C catalysts show certain advantages in areas such as oxygen evolution reactions, their catalytic activity falls far short of practical requirements when applied to the CO2 reduction reaction scenario in CO2 / H2 fuel cells. Specifically, they cannot effectively reduce the activation energy of the CO2 reduction reaction, making it difficult to accelerate the reaction kinetics. Ultimately, this results in a low CO2 conversion rate and efficiency, failing to meet the performance requirements of the battery system.

[0029] CO2 molecules possess good thermodynamic stability. The double bonds in CO2 molecules exhibit partial triple bond properties, with short bond lengths and bond energies as high as 750 kJ / mol. The carbon-oxygen bond is difficult to break, leading to challenging adsorption and activation, and a slow kinetic reaction. Furthermore, the carbon atom in the CO2 molecule is electrophilic, requiring an external electron donation for activation. In principle, the effective adsorption and activation of carbon dioxide on the catalyst surface is the primary and crucial step in the entire process. For carbon dioxide activation, the formation of carbon dioxide adsorption free radicals (CO2) first occurs through an electron transfer process. - *), which is then transferred via proton transfer to form a carboxyl adsorption intermediate (COOH*), or through proton-electron co-transfer (where * represents the adsorption site). Regardless of the pathway, rapid electron transfer is a crucial prerequisite.

[0030] Based on the above, this application proposes a RuO2 / C functionalized composite material, its preparation method, and its application. The following is a detailed description of this application in conjunction with embodiments and accompanying drawings.

[0031] This application proposes a RuO2 / C functionalized composite material, characterized in that it includes carbon spheres; RuO2 particles are attached to the surface of the carbon spheres, and the surface of the RuO2 particles is coated with a carbon layer. The carbon layer and the surface of the carbon spheres have unpaired electrons that can rapidly transfer electrons to CO2.

[0032] This application uses carbon spheres as the core support carrier, which possesses a high specific surface area and good electronic conductivity. These spheres provide stable attachment sites for RuO2 particles, preventing particle aggregation, and also construct efficient electron transport channels, ensuring rapid electron transfer during the reaction. The RuO2 particles uniformly attached to the carbon sphere surface are the basic active units of the catalytic reaction, possessing inherent CO2 reduction catalytic potential and providing core catalytic sites for the reaction. The carbon layer coating the RuO2 particle surface is not a simple inert coating structure, but a specially treated active carbon layer rich in unpaired electrons. These unpaired electrons act as electron donors, interacting strongly with CO2 molecules. Through electron transfer, they weaken the stable C=O double bonds in the CO2 molecule, causing them to bend, elongate, and thus activate, solving the key problem of CO2 molecule activation difficulty. Furthermore, these unpaired electrons can also transfer to the Ru metal sites and oxygen sites within the RuO2 particles, altering the electronic state density of Ru and O. This breaks the traditional understanding that only the metal center is an active site, allowing Ru and O to jointly become highly efficient active sites, significantly increasing the number of active centers in the catalytic reaction. Meanwhile, the carbon layer coating structure can also provide physical protection for RuO2 particles, preventing them from being eroded or deactivated in the thermal environment of fuel cells, thus ensuring the long-term stability of the catalyst. The multi-level carbon structure formed by the carbon sphere substrate and the surface carbon layer can also optimize the diffusion channels of reactant CO2 and product methane, further improving the reaction kinetic rate. Ultimately, through this synergistic design, a simultaneous leap in the activity, selectivity and stability of the CO2 reduction reaction is achieved.

[0033] In RuO2 / C functionalized composite materials, the RuO2 particles are nanoparticles with a size of 1 nm- The 10nm particle size of RuO2 gives it a large specific surface area, which is beneficial for enhancing its catalytic activity. This application effectively solves the problems of activity and stability of cathode catalysts in the CO2 reduction process by confining RuO2 particles to the nanoscale and precisely controlling their size range. Nanoscale RuO2 particles have a high specific surface area, significantly increasing the number of exposed active sites and providing more reaction sites for CO2 molecules. Meanwhile, the size range of 1nm- Within 10 nm, it prevents agglomeration caused by excessively small particles and avoids the reduction in active site density caused by excessively large sizes, thus achieving a balance between catalytic activity and structural stability in the CO2 reduction reaction.

[0034] In a preferred embodiment, the mass percentage of RuO2 in the RuO2 / C functionalized composite material is 1%-80%, a range that can meet the needs of different application scenarios. In a more preferred embodiment, the mass percentage of RuO2 in the RuO2 / C functionalized composite material is 50%-80%, within which the material exhibits superior catalytic performance. The mass percentage of RuO2 is used to optimize catalytic activity; however, inappropriate RuO2 content can lead to low CO2 reduction efficiency. Specifically, if the content is too low, there are insufficient active sites to effectively drive the reaction; if the content is too high, it can easily cause particle aggregation, structural damage, and increased side reactions, thus failing to achieve stable high conversion efficiency. When the mass percentage of RuO2 is strictly limited to 1%-80%, RuO2 particles form a moderate load on the carbon sphere surface, the carbon layer coating structure remains intact, and the unpaired electron conduction pathway is not disturbed. This range allows RuO2, as the core catalytic component, to provide sufficient active sites for CO2 reduction while maintaining the dispersion and support of the carbon sphere support for the particles. This synergistically optimizes the electron transfer capability and structural stability of the material, effectively overcoming the limitation of catalytic efficiency caused by content imbalance. When the mass ratio is optimized to 50%-80%, the interfacial interaction between RuO2 and the carbon matrix is ​​optimized, ensuring both efficient adsorption and activation of CO2 molecules in the cathode reaction and inhibiting the migration and aggregation of RuO2 particles at high contents, thereby maintaining the structural stability and effective reaction area of ​​the catalyst.

[0035] As an example, in addition to unpaired electrons on the carbon layer surface, they can originate from functional groups such as hydroxyl, carboxyl, and carbonyl groups. These unpaired electrons endow RuO2 / C functionalized composite materials with excellent electrocatalytic performance. It should be noted that hydroxyl groups can be introduced through surface oxidation treatment or chemical modification to enhance surface hydrophilicity and promote the adsorption and enrichment of CO2 molecules. Carboxyl groups are acidic functional groups present on the carbon layer surface and can be formed by treating carbon materials with acidic oxidants to strengthen surface acidic sites, which is beneficial for the directional activation of CO2. Carbonyl groups are used as electron acceptors to lower the energy barrier of reduction reactions. This application introduces oxygen-containing functional groups such as hydroxyl, carboxyl, or carbonyl groups onto the carbon layer and carbon sphere surface, creating abundant unpaired electrons on the carbon layer and carbon sphere surface to optimize the chemical environment of the catalyst surface. Specifically, the hydroxyl group provides a proton transfer channel to stabilize the reaction intermediate, the carboxyl group promotes the directional adsorption and activation of CO2 molecules through acidic sites, and the carbonyl group improves the electron transfer path through its electron acceptor properties. If the three are used in combination, their synergistic effect can effectively compensate for the limitations of a single unpaired electron at the active site, thereby improving the overall performance of the CO2 reduction reaction.

[0036] This application also proposes a method for preparing RuO2 / C functionalized composite materials, which may include: (1) Add the carbon precursor to deionized water and stir until homogeneous to obtain a dispersion.

[0037] (2) Add RuO2 particles to the dispersion and stir until homogeneous to obtain a mixed solution.

[0038] (3) The mixed solution is subjected to a hydrothermal reaction at a first temperature. After the reaction is completed, it is cooled to room temperature. The solid part is taken and dried at a second temperature to obtain a dried sample. The first temperature is greater than the second temperature.

[0039] (4) Grind the mixed dry sample to obtain RuO2 / C functionalized composite material.

[0040] A hydrothermal reaction using a carbon precursor, followed by a mild oxidation treatment, forms hydroxyl and carboxyl functional groups on the carbon layer surface and carbon spheres, thereby enhancing its adsorption capacity and activation efficiency for CO2 molecules. This effectively improves the chemical environment of the catalyst surface, enhances the adsorption and activation capacity of CO2 molecules, and improves the selectivity and activity of the CO2 reduction reaction, thus solving the technical problem of low CO2 conversion efficiency. The first temperature of the hydrothermal reaction is precisely controlled to be higher than the second temperature of the drying process, thus maintaining the nanoscale size of RuO2 particles while preserving the unpaired electron characteristics of the carbon layer surface. The hydrothermal reaction at a suitable temperature promotes carbonization and fixes the RuO2 particles, while the lower-temperature drying process avoids damage to the carbon layer structure caused by high temperatures, maintaining the unpaired electron characteristics. The grinding operation further increases the specific surface area of ​​the material and exposes active sites.

[0041] The following are some embodiments of the preparation method of this application, which will further illustrate this application in detail.

[0042] Example 1 (1) Add 480 mg of glucose powder to 28 mL of deionized water, sonicate the solution for 10-30 min, and magnetically stir for 30-60 min to obtain a dispersion.

[0043] (2) Add 400 mg RuO2 nanoparticles to the dispersion, then continue sonication for 30 min and magnetic stirring for 10-30 min to obtain a mixed solution.

[0044] (3) Transfer the mixed solution to a stainless steel reactor and hydrothermally heat it at 180°C for 18 h.

[0045] (4) After the hydrothermal reaction is completed, the mixed solution obtained is cooled to room temperature, then vacuum filtered and washed with deionized water and acetone until neutral.

[0046] (5) Dry the sample obtained in step (4) at 80°C for 12 hours.

[0047] (6) Grind and weigh the sample after drying in step (5), and finally seal and store it.

[0048] Example 2 (1) Add 350 mg of glucose powder to 28 mL of deionized water, sonicate the solution for 10-30 min, and magnetically stir for 30-60 min to obtain a dispersion.

[0049] (2) Add 100 mg RuO2 nanoparticles to the dispersion, then continue sonication for 30 min and magnetic stirring for 10-30 min to obtain a mixed solution.

[0050] (3) Transfer the mixed solution to a stainless steel reactor and hydrothermally heat it at 200°C for 18 h.

[0051] (4) After the hydrothermal reaction is completed, the mixed solution obtained is cooled to room temperature, then vacuum filtered and washed with deionized water and acetone until neutral.

[0052] (5) Dry the sample obtained in step (4) at 60°C for 12 hours.

[0053] (6) Grind and weigh the sample after drying in step (5), and finally seal and store it.

[0054] Example 3 (1) Add 200mg of glucose powder to 28 mL of deionized water, sonicate the solution for 10-30 min, and magnetically stir for 30-60 min to obtain a dispersion.

[0055] (2) Add 300 mg RuO2 nanoparticles to the dispersion, then continue sonication for 30 min and magnetic stirring for 10-30 min to obtain a mixed solution.

[0056] (3) Transfer the mixed solution to a stainless steel reactor and hydrothermally heat it at 260°C for 18 h.

[0057] (4) After the hydrothermal reaction is completed, the mixed solution obtained is cooled to room temperature, then vacuum filtered and washed with deionized water and acetone until neutral.

[0058] (5) Dry the sample obtained in step (4) at 100°C for 12 hours.

[0059] (6) Grind and weigh the sample after drying in step (5), and finally seal and store it.

[0060] Example 4 (1) Add 100 mg of glucose powder to 28 mL of deionized water, sonicate the solution for 10-30 min, and magnetically stir for 30-60 min to obtain a dispersion.

[0061] (2) Add 350 mg RuO2 nanoparticles to the dispersion, then continue sonication for 30 min and magnetic stirring for 10-30 min to obtain a mixed solution.

[0062] (3) Transfer the mixed solution to a stainless steel reactor and hydrothermally heat it at 180°C for 18 h.

[0063] (4) After the hydrothermal reaction is completed, the mixed solution obtained is cooled to room temperature, then vacuum filtered and washed with deionized water and acetone until neutral.

[0064] (5) Dry the sample obtained in step (4) at 70°C for 12 hours.

[0065] (6) Grind and weigh the sample after drying in step (5), and finally seal and store it.

[0066] Example 5 (1) Add 400 mg of glucose powder to 28 mL of deionized water, sonicate the solution for 10-30 min, and magnetically stir for 30-60 min to obtain a dispersion.

[0067] (2) Add 400 mg RuO2 nanoparticles to the dispersion, then continue sonication for 30 min and magnetic stirring for 10-30 min to obtain a mixed solution.

[0068] (3) Transfer the mixed solution to a stainless steel reactor and hydrothermally heat it at 160°C for 18 h.

[0069] (4) After the hydrothermal reaction is completed, the mixed solution obtained is cooled to room temperature, then vacuum filtered and washed with deionized water and acetone until neutral.

[0070] (5) Dry the sample obtained in step (4) at 80°C for 12 hours.

[0071] (6) Grind and weigh the sample after drying in step (5), and finally seal and store it.

[0072] It should be noted that in other embodiments of this application, the carbon precursor can be glucose, sucrose, or a mixture of glucose and sucrose, that is, glucose can be replaced in the above embodiments to obtain more embodiments.

[0073] In the above embodiments, the functional groups on the surface of the carbon layer and carbon spheres can be at least one of hydroxyl, carboxyl, and carbonyl groups.

[0074] This application uses a hydrothermal method to coat the surface of RuO2 with a carbon layer and load it onto carbon spheres. This composite material has abundant unpaired electrons, which not only makes the process very simple, but also ensures the uniformity and dispersion of metal nanoparticles.

[0075] A CO2 / H2 fuel cell is a device that utilizes low-temperature waste heat (≤200°C) to simultaneously generate electricity and reduce carbon dioxide. The CO2 / H2 fuel cell includes an anode and a cathode. The anode catalyzes the oxidation of H2 and can employ a commercially available Pt / C catalyst. The cathode uses the composite material proposed in this application as the electrocatalyst. In this embodiment, as a preferred embodiment, an acidic electrolyte membrane, such as a polybenzimidazole phosphate membrane, is used. The reaction gas is H2 or a mixture of hydrogen and an inert gas introduced at the anode, and CO2 or a mixture of CO2 and an inert gas introduced at the cathode. The composite material of Example 1 and the CO2 / H2 fuel cell using this composite material were then tested and verified. Figure 1 The diagram shown is a schematic representation of the preparation principle of Embodiment 1 of this application. Figure 2 The image shown is a SEM image of the RuO2 / C functionalized composite material prepared in Example 1 of this application. The scale bar is 1 μm. Figure 2 It can be seen that the main morphology of the RuO2 / C composite catalyst is RuO2 nanoparticles supported on carbon spheres. For example... Figure 3 The image shown is a TEM image of the RuO2 / C functionalized composite material prepared in Example 1 of this application. The scale bar is 10 nm. Figure 3 It can be seen that the RuO2 surface in the RuO2 / C composite catalyst is covered with a carbon layer. For example... Figure 4 The image shown is the Fourier transform infrared spectrum of the RuO2 / C functionalized composite material prepared in Example 1 of this application. The RuO2 / C composite material is rich in various functional groups: hydroxyl, carboxyl, carbonyl, etc. Figure 5 The image shows the electron paramagnetic resonance spectrum of the RuO2 / C functionalized composite material prepared in Example 1 of this application. It can be seen that the RuO2 / C catalyst composite material contains extremely abundant unpaired electrons. Figure 6 The figure shows the methane yield of the RuO2 / C functionalized composite material prepared in Example 1 of this application for CO2 reduction. The RuO2 / C composite catalyst, used in a CO2 / H2 fuel cell for CO2 reduction, exhibits the highest CH4 yield at 190°C, reaching 1441.7 ppm, with a conversion rate of 1242.5 μmol gcat. -1 h -1 The current contribution ratio is 10.1%. For example... Figure 7The figure shown is a graph illustrating the methane yield of the RuO2 / C functionalized composite material prepared in Example 1 of this application for CO2 reduction. This application effectively increases the battery reaction area. The RuO2 / C composite catalyst, used in a CO2 / H2 fuel cell for CO2 reduction, achieves a CH4 yield of 3429 ppm at 190°C, with a current contribution ratio of 28.2%. Figure 6 The reaction area of ​​the CO2 / H2 fuel cell electrode plates used is 9 square centimeters. Figure 7 The CO2 / H2 fuel cell electrode plate used has a reaction area of ​​24 square centimeters. A larger reaction contact area provides CO2 with a longer reaction path and more reaction opportunities, thereby improving CO2 conversion efficiency. This demonstrates that the system can rapidly improve CO2 conversion efficiency by increasing the reaction area of ​​the device. Figure 8 The figure shows the discharge curve of the RuO2 / C functionalized composite material prepared in Example 1 of this application for CO2 reduction. The RuO2 / C composite catalyst exhibits the highest current density of 4.25 mA cm⁻¹ at 190 °C for CO2 reduction. -2 The power density is 0.12 mW / cm². -2 .

[0076] This application discloses the application of RuO2 / C composite materials rich in unpaired electrons in a novel CO2 / H2 fuel cell technology, effectively improving the CO2 reduction rate and conversion efficiency. Experimental verification also demonstrates that this invention is not a simple superposition of known materials and devices. In the specific thermal environment of this CO2 / H2 fuel cell, the RuO2 / C composite material rich in unpaired electrons can effectively adsorb and activate CO2, causing the C=O double bonds of the very stable CO2 molecule to bend and elongate, thereby activating it. The unpaired electrons in the composite material are effectively transferred to Ru metal sites and oxygen sites, making both Ru and O reactive sites, effectively adsorbing and activating CO2. This mechanism also breaks the commonly held belief that the active site is at the metal center of an oxide system, and is something that cannot be achieved by using RuO2 or carbon materials alone, or even other known catalysts.

[0077] Detailed comparative experiments have demonstrated that the cathode using the composite material of this application can achieve a CO2-to-methane rate of 1242.5 μmol gcat. - ¹ h -¹, this is 18 times that of RuO2 loaded on carbon nanotubes (RuO2 / CNTs), and the current contribution to methane generation is 28.2% (compared to 1.5% for RuO2 / CNTs). This significant performance improvement demonstrates the outstanding advantages of this application. Therefore, this application does not require the development of entirely new and complex material systems or major modifications to the battery structure. Through ingenious catalyst selection, it achieves a qualitative leap in system performance in a simple and low-cost manner, providing a highly valuable solution for the commercial application of CO2 reduction catalysts.

[0078] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A RuO2 / C functionalized composite material, characterized in that, The carbon sphere has RuO2 particles attached to the surface of the carbon sphere, and the RuO2 particles have a carbon layer coated on the surface of the RuO2 particles, and the carbon layer and the surface of the carbon sphere both have unpaired electrons.

2. The Ru02 / C functionalized composite material according to claim 1, characterized in that, The mass ratio of RuO2 in the RuO2 / C functional composite material is 1%-80%.

3. The Ru02 / C functionalized composite material according to claim 2, characterized in that, The mass ratio of RuO2 in the RuO2 / C functional composite material is 50%-80%.

4. The Ru02 / C functionalized composite material according to claim 1, characterized in that, The RuO2 particles are nanoparticles, and the size of the RuO2 particles is 1nm-10nm.

5. The use of the RuO2 / C functional composite material according to any one of claims 1 to 4 as a cathode thermoelectric catalyst for a CO2 / H2 fuel cell.

6. Use of the RuO2 / C functionalized composite material according to claim 5 as a cathode thermoelectric catalyst for CO2 / H2 fuel cells, characterized by the fact that, The CO2 / H2 fuel cell comprises an anode, a cathode, an electrolyte membrane and a reaction gas; The electrolyte membrane is an acid electrolyte membrane containing phosphoric acid as an electrolyte; The reaction gas comprises H2 or a mixture of H2 and inert gas introduced into the anode, and CO2 or a mixture of CO2 and inert gas introduced into the cathode.

7. A method for preparing the RuO2 / C functional composite material according to any one of claims 1 to 4, characterized in that, The method comprises: adding a carbon precursor into deionized water and stirring until uniform to obtain a dispersion; adding RuO2 particles into the dispersion and stirring until uniform to obtain a mixed solution; subjecting the mixed solution to hydrothermal reaction at a first temperature, cooling to room temperature after the reaction is completed, and drying the solid part at a second temperature to obtain a dried sample; the first temperature is greater than the second temperature; grinding the dried sample to obtain a RuO2 / C functional composite material.

8. The method for preparing a RuO2 / C functionalized composite material according to claim 7, characterized in that, The carbon precursor is at least one of glucose and sucrose.

9. The method of claim 7, wherein the RuO2 / C functionalized composite material is prepared by the steps of: The first temperature is less than or equal to 260℃.

10. The method for preparing a RuO2 / C functionalized composite material according to claim 9, characterized in that, The second temperature is 60℃-100℃.

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