Cathode catalyst and preparation method thereof, cathode electrode, water electrolysis hydrogen production device and hydrogen production system
By using a cathode catalyst supported by metal elements such as Fe, Co, Ni in electrolytic water hydrogen production technology, the problem of high cost and insufficient stability of precious metal catalysts is solved, and low cost, high stability and high efficiency are achieved Hydrogen gas is generated.
Patent Information
- Application Number
- CN202411421215.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-12
- Publication Date
- 2024-12-10
AI Technical Summary
In the existing electrolytic hydrogen production technology, the high cost and stability of precious metal catalysts are insufficient, which limits their promotion in large-scale applications.
Carbon aerogel is used as a support and supports cathode catalysts for metal elements such as Fe, Co, Ni, etc., and is prepared by hydrothermal reaction. Combining the porous structure of carbon aerogel and the electrostatic interaction of metal elements, the stability and activity of the catalyst are improved. .
A cathode catalyst with low cost and high stability is realized, which extends the service life of the electrode, and improves the electrolytic efficiency and energy consumption of the electrolytic water hydrogen production device.
Smart Images
Figure CN119101939A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of hydrogen production by electrolysis of water, and specifically to a cathode catalyst and a preparation method thereof, a cathode electrode, a hydrogen production device by electrolysis of water, and a hydrogen production system. Background Art
[0002] Hydrogen has two major advantages in its use as an energy source: high energy density and no pollution. Among the methods of preparing hydrogen, the hydrogen produced by electrolysis of water has the advantages of high purity and easy collection and storage, so it has been widely used.
[0003] There are two main half reactions in the electrolysis of water to produce hydrogen: the hydrogen evolution reaction (HER) occurs at the cathode, and the oxygen evolution reaction (OER) occurs at the anode. For hydrogen evolution catalysts, the cathode catalyst should not only have excellent catalytic hydrogen evolution performance, but also be able to work stably for a long time at high current density. Pt and Pt-based precious metal materials have high electrolytic catalytic activity, but their high price limits their large-scale application; supported precious metal catalyst materials have low cost, but have poor stability. Summary of the invention
[0004] Based on this, the present application provides a cathode catalyst and a preparation method thereof, a cathode electrode, a water electrolysis hydrogen production device, and a hydrogen production system. The cathode catalyst provided in the present application has the advantages of low cost and strong stability.
[0005] In a first aspect of the present application, a cathode catalyst is provided, comprising a carbon aerogel and an active component supported on the carbon aerogel, wherein the active component comprises one or more of Fe, Co, Ni and Mn.
[0006] In one embodiment, the active component includes at least two of Fe, Co, Ni and Mn.
[0007] In one embodiment, the active component includes Mn element and Co element; or,
[0008] The active components include Fe element and Ni element.
[0009] In one embodiment, in the active component, the molar ratio of the Mn element to the Co element is 1:(0.5-2); or,
[0010] In the active component, the molar ratio of the Fe element to the Ni element is 1:(0.5-2).
[0011] In one embodiment, in the active component, the molar ratio of the Mn element to the Co element is 1:(0.5~2).
[0012] In one embodiment, in the cathode catalyst, the mass ratio of the metal element included in the active component to the carbon aerogel is (1-1.5): 1. In one embodiment, the carbon aerogel is a cellulose-based carbon aerogel.
[0013] In a second aspect of the present application, there is provided a method for preparing the cathode catalyst according to any one of the embodiments of the first aspect of the present application, comprising the following steps:
[0014] Mixing the active precursor material and the carbon aerogel in a solution to prepare a mixed solution;
[0015] subjecting the mixed solution to a hydrothermal reaction to prepare the cathode catalyst;
[0016] Wherein, the active precursor material includes one or more of iron salt, cobalt salt, nickel salt and manganese salt.
[0017] In one embodiment, the active precursor material includes at least two of iron salt, cobalt salt, nickel salt and manganese salt.
[0018] In one embodiment, the active precursor material includes manganese acetate tetrahydrate and cobalt chloride hexahydrate; or,
[0019] The active precursor materials include ferric chloride hexahydrate and nickel chloride hexahydrate.
[0020] In one embodiment, the molar ratio of the manganese acetate tetrahydrate to the cobalt chloride hexahydrate in the active precursor material is 1:(0.5-2); or,
[0021] The molar ratio of the ferric chloride hexahydrate to the nickel chloride hexahydrate in the active precursor material is 1:(0.5-2).
[0022] In one embodiment, the mass ratio of the metal element included in the active precursor material to the carbon aerogel is (1-1.5):1.
[0023] In one embodiment, the molar ratio of the manganese acetate tetrahydrate to the cobalt chloride hexahydrate in the active precursor material is 1:(0.5-2).
[0024] In one embodiment, the process parameters of the hydrothermal reaction include: the reaction temperature is 170°C~180°C.
[0025] In one embodiment, the method for preparing the carbon aerogel comprises the following steps:
[0026] The cellulose solution is pre-frozen at -80°C to -20°C and then freeze-dried to prepare cellulose aerogel;
[0027] The cellulose aerogel is carbonized in an inert gas atmosphere to prepare the carbon aerogel.
[0028] In a third aspect of the present application, a cathode electrode is provided, comprising an electrode substrate and a catalyst loaded on the electrode substrate, wherein the catalyst comprises the cathode catalyst described in any one of the embodiments of the first aspect of the present application.
[0029] In a fourth aspect of the present application, a device for producing hydrogen by electrolysis of water is provided, comprising a cathode electrode, an anode electrode and an electrolyte, wherein the cathode electrode and the anode electrode are arranged relatively spaced apart in the electrolyte, the cathode electrode is the cathode electrode described in the third aspect of the present application, and the electrolyte is an alkaline solution with a mass fraction of 25% to 35%.
[0030] In a fifth aspect of the present application, a hydrogen production system is provided, comprising the water electrolysis hydrogen production device described in the third aspect of the present application.
[0031] In the cathode catalyst provided in the present application, the active components include one or more of Fe, Co, Ni and Mn. Among them, Fe, Co, Ni and Mn are cheaper than Pt, and can promote the adsorption and desorption of hydrogen to improve the hydrogen evolution activity; at the same time, the positively charged metal elements in the cathode catalyst can fit tightly with the cathode substrate through electrostatic interaction to reduce the shedding of active components. Further synergistic carbon aerogel, carbon aerogel has an excellent porous structure and high specific surface area, can provide good support, help to fix the active components on the electrode, and form a stable structure, so as to avoid the shedding, loss or dispersion of active components, thereby extending the service life of the electrode and ensuring the long-term operation stability of the electrolytic water hydrogen production device.
[0032] Furthermore, the cathode catalyst provided in the present application is low-priced, can effectively ensure the electrolysis efficiency of the water electrolysis hydrogen production device, and reduce the energy consumption of the hydrogen production system. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 This is an operating time-voltage curve of the cathode electrode in Example 1 of the present application. DETAILED DESCRIPTION
[0034] The cathode catalyst and preparation method thereof, cathode electrode, water electrolysis hydrogen production device, and hydrogen production system of the present application are further described in detail below in conjunction with specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.
[0035] With the increase in the consumption of non-renewable energy, people's demand for green and clean energy continues to increase. Hydrogen energy, as an efficient and clean energy, is one of the more popular energy sources at present. Among the current commercial hydrogen production technologies, water electrolysis is mature and widely used. Among them, alkaline water electrolysis is an important technology for large-scale hydrogen production and is also one of the most mature hydrogen production technologies.
[0036] In alkaline water electrolysis, the electrolyzer is its core component, and the catalyst on the surface of the electrode substrate of the electrolyzer is the key to the energy efficiency of water electrolysis. Currently, the materials with good performance for preparing hydrogen evolution reaction electrocatalysts include precious metals, but due to the high cost and scarcity of precious metals, they cannot be commercially promoted. Therefore, it is very important to provide a cathode catalyst that can reduce the content of precious metals and ensure the stability of electrolysis.
[0037] Based on this, in the first aspect of the present application, a cathode catalyst is provided, comprising a carbon aerogel and an active component loaded on the carbon aerogel, wherein the active component comprises one or more of Fe element, Co element, Ni element and Mn element.
[0038] In the cathode catalyst provided in the present application, the active components include one or more of Fe, Co, Ni and Mn. Among them, the prices of Fe, Co, Ni and Mn are relatively low compared to Pt, and their synergistic carbon aerogel materials can improve the hydrogen evolution activity; at the same time, the positive metal elements in the cathode catalyst can fit closely with the cathode matrix through electrostatic interaction, reducing the shedding of active components; and the carbon aerogel has an excellent porous structure and a high specific surface area, which can provide good support, help to fix the active components on the electrode, and form a stable structure, so as to avoid the shedding, loss or dispersion of the active components, thereby extending the service life of the electrode and ensuring the long-term operation stability of the electrolytic water hydrogen production device.
[0039] Furthermore, the cathode catalyst provided in the present application is low-priced, can effectively ensure the electrolysis efficiency of the water electrolysis hydrogen production device, and reduce the energy consumption of the electrolysis system.
[0040] Preferably, the active component includes at least two of the Fe element, the Co element, the Ni element and the Mn element. The cathode catalyst provided in the present application preferably includes active components of at least two metal elements, and the compounding of the two active components helps to accelerate the electrolysis reaction of water molecules and promote the rate of hydrogen production; at the same time, the cathode catalyst compounded of the two active components has high durability in the cathode electrode and can maintain catalytic activity for a long time. Furthermore, in the hydrogen evolution reaction, some impurities or pollutants will adhere to the electrode surface, but at this time, the catalyst compounded of the two active components has good electron transfer performance and can quickly transfer electrons from the electrode to the catalytic active site, which helps the cathode electrode to maintain its catalytic activity in the presence of pollutants and reduce the impact of pollutants on electrode performance.
[0041] Preferably, the active component includes Mn element and Co element; or,
[0042] The active components include Fe element and Ni element.
[0043] Mn and Co elements, or Fe and Ni elements as active components, can synergistically effectively promote the adsorption and conversion of water on the surface of the cathode catalyst, improve the catalytic activity of the hydrogen evolution reaction, and accelerate the generation rate of hydrogen; at the same time, Mn and Co elements, Fe and Ni elements have different electronic structures and chemical properties, which can form complementary active sites on the catalyst surface to improve the overall activity of the catalyst, accelerate the generation rate of hydrogen, reduce the starting potential of the reaction, and delay the deactivation efficiency of the catalyst.
[0044] In order to better regulate the active center, effectively control the active structure on the catalyst surface, promote the two elements M to form more complementary active sites, improve the activity and selectivity of the catalyst; and slow down the deactivation efficiency of the catalyst and strengthen the stability of the cathode catalyst. In one example, in the active component, the molar ratio of the Mn element to the Co element is 1: (0.5~2). It can be understood that in the active component, the molar ratio of the Mn element to the Co element can be selected from any value between 1: (0.5~2). Specifically, the molar ratio of the Mn element to the Co element includes but is not limited to 1: 0.5, 1: 0.6, 1: 0.7, 1: 0.8, 1: 0.9, 1: 1, 1: 1.1, 1: 1.2, 1: 1.3, 1: 1.4, 1: 1.5, 1: 1.6, 1: 1.7, 1: 1.8, 1: 1.9 or 1: 2; or within the range of any two of the above point values as end values.
[0045] In another example, in the active component, the molar ratio of the Fe element to the Ni element is 1: (0.5~2). It can be understood that in the active component, the molar ratio of the Fe element to the Ni element can be selected from any value between 1: (0.5~2). Specifically, the molar ratio of the Fe element to the Ni element includes but is not limited to 1: 0.5, 1: 0.6, 1: 0.7, 1: 0.8, 1: 0.9, 1: 1, 1: 1.1, 1: 1.2, 1: 1.3, 1: 1.4, 1: 1.5, 1: 1.6, 1: 1.7, 1: 1.8, 1: 1.9 or 1: 2; or within the range formed by any two of the above point values as end values.
[0046] In one example, in the cathode catalyst, the mass ratio of the metal element included in the active component to the mass ratio of the carbon aerogel is (1~1.5):1. By limiting the mass ratio of the carbon aerogel to the metal element included in the active component, the stability of the catalyst carrier structure can be improved, wherein a suitable mass ratio can ensure that the active component is effectively loaded on the surface of the carbon aerogel carrier, enhance the structural stability of the cathode catalyst, improve the utilization rate of the active component and the number of active sites exposed on the surface, thereby enhancing the activity and catalytic stability of the catalyst. It can be understood that in the cathode catalyst, the mass ratio of the metal element included in the active component to the mass ratio of the carbon aerogel can be selected from any value between (1~1.5):1. Specifically, in the cathode catalyst, the mass ratio of the metal element included in the active component to the mass ratio of the carbon aerogel includes but is not limited to 1:1, 1.1:1, 1.15:1, 1.18:1, 1.2:1, 1.22:1, 1.25:1, 1.28:1, 1.3:1, 1.35:1, 1.4:1 or 1.5:1.
[0047] In one example, the active component includes a manganese compound and a cobalt compound. For example, the manganese compound is one or more of Mn2O3 and Mn(OH)3. The cobalt compound is one or more of CoO, Co2O3, Co3O4 and Co(OH)2.
[0048] In another example, the active component includes an iron compound and a nickel compound. For example, the iron compound includes one or more of Fe2O3, Fe3O4, and Fe(OH)3. The nickel compound includes one or more of NiO, Ni2O3, and Ni3O4.
[0049] In one example, the carbon aerogel is a cellulose-based carbon aerogel.
[0050] In a second aspect of the present application, there is provided a method for preparing the cathode catalyst as described in any example of the first aspect of the present application, comprising the following steps:
[0051] a1. Mixing the active precursor material and the carbon aerogel in a solution to prepare a mixed solution;
[0052] a2. subjecting the mixed solution to a hydrothermal reaction to prepare the cathode catalyst;
[0053] Wherein, the active precursor material includes one or more of iron salt, cobalt salt, nickel salt and manganese salt.
[0054] The preparation method provided by the present application has simple steps, mild conditions, does not require complex process conditions, can complete the preparation process in a relatively short time, and is easy to achieve large-scale preparation of cathode catalysts. In addition, in the preparation method provided by the present application, the active precursor materials used include common substances such as iron salts, cobalt salts, nickel salts and manganese salts. These raw materials are easy to obtain and help to improve the electrocatalytic activity and stability of the catalyst. In addition, using carbon aerogel as a carrier material can increase the specific surface area and conductivity of the catalyst and enhance its electrocatalytic performance.
[0055] In one example, the active precursor material includes manganese acetate tetrahydrate and cobalt chloride hexahydrate.
[0056] Manganese acetate tetrahydrate (MnC4H6O4·4H2O) and cobalt chloride hexahydrate (CoCl2·6H2O) are commonly used transition metal complexes, which can be converted into active manganese-based catalysts and cobalt-based catalysts under hydrothermal reaction conditions. These catalysts maintain their catalytic activity during long-term use.
[0057] In another example, the active precursor material includes ferric chloride hexahydrate and nickel chloride hexahydrate.
[0058] In one example, the molar ratio of the manganese acetate tetrahydrate to the cobalt chloride hexahydrate in the active precursor material is 1: (0.5-2). It can be understood that the molar ratio of the manganese acetate tetrahydrate to the cobalt chloride hexahydrate in the active precursor material can be selected from any value between 1: (0.5-2). Specifically, the molar ratio of the manganese acetate tetrahydrate to the cobalt chloride hexahydrate in the active precursor material includes but is not limited to 1: 0.5, 1: 0.6, 1: 0.7, 1: 0.8, 1: 0.9, 1: 1, 1: 1.1, 1: 1.2, 1: 1.3, 1: 1.4, 1: 1.5, 1: 1.6, 1: 1.7, 1: 1.8, 1: 1.9 or 1: 2.
[0059] In another example, the molar ratio of the ferric chloride hexahydrate to the nickel chloride hexahydrate in the active precursor material is 1:(0.5~2). It can be understood that the molar ratio of the ferric chloride hexahydrate to the nickel chloride hexahydrate in the active precursor material can be selected from any value between 1:(0.5~2). Specifically, the molar ratio of the ferric chloride hexahydrate to the nickel chloride hexahydrate in the active precursor material includes but is not limited to 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2.
[0060] In one example, the mass ratio of the metal element included in the active precursor material to the carbon aerogel is (1~1.5):1. Mixing the active precursor material and the carbon aerogel within the above range can ensure the mass proportion of the carbon aerogel in the cathode catalyst or the mass proportion of the metal element included in the active component of the cathode catalyst. Furthermore, the mass ratio of the metal element included in the active precursor material to the carbon aerogel includes but is not limited to 1:1, 1.1:1, 1.15:1, 1.18:1, 1.2:1, 1.22:1, 1.25:1, 1.28:1, 1.3:1, 1.35:1, 1.4:1 or 1.5:1.
[0061] By adjusting the mass fraction of the active precursor material in the mixed solution, the composition and performance of the final cathode catalyst can be adjusted to achieve controllable preparation of the cathode catalyst. In one example, in the mixed solution, the mass fraction of the active precursor material is 4wt%~10%. It can be understood that in the mixed solution, the mass fraction of the active precursor material can be selected from any value between 4wt%~10%. Specifically, the mass fraction of the active precursor material includes but is not limited to 4wt%, 5wt%, 5.5wt%, 5.8wt%, 5.9wt%, 6wt%, 6.1wt%, 6.2wt%, 6.4wt%, 6.5wt%, 6.8wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt% or 10wt%.
[0062] In one example, the process parameters of the hydrothermal reaction include: a reaction temperature of 170°C to 180°C. Limiting the temperature of the hydrothermal reaction can increase the reaction rate and accelerate the reaction process of the active precursor material and the carbon aerogel; at the same time, the reaction temperature can also promote the interaction reaction between the active precursor material and the carbon aerogel, which helps to form a uniform cathode catalyst. It can be understood that the reaction temperature of the hydrothermal reaction can be selected from any value between 170°C and 180°C. Specifically, the reaction temperature of the hydrothermal reaction includes but is not limited to 170°C, 171°C, 172°C, 173°C, 174°C, 175°C, 176°C, 177°C, 178°C, 179°C or 180°C.
[0063] In one example, the method for preparing the carbon aerogel comprises the following steps:
[0064] b4, pre-freezing the cellulose solution at -80°C to -20°C, and then freeze-drying it to prepare cellulose aerogel;
[0065] b5. Carbonizing the cellulose aerogel in an inert gas atmosphere to prepare the carbon aerogel.
[0066] In step b4, the cellulose solution is pre-frozen, and the water in the cellulose solution is frozen into ice crystals to form a porous structure; then freeze-dried, the ice crystals sublimate and leave pores to obtain cellulose aerogel. In step b5, the cellulose aerogel is carbonized, and the cellulose carbon skeleton gradually loses elements such as hydrogen and oxygen to form a carbon aerogel with high conductivity and high surface area.
[0067] In one example, the method for preparing the cellulose solution comprises the following steps:
[0068] b1. Dissolving wood powder in a solution dispersed with an oxidant and an organic acid, heating in a water bath at a temperature of 70°C to 80°C, washing with water, and removing the supernatant to obtain holocellulose;
[0069] b2, mixing the holocellulose with a KOH aqueous solution, heating the mixture in a water bath at a temperature of 85° C. to 95° C., washing the mixture with water, and removing the supernatant to obtain cellulose;
[0070] b3. Mixing the cellulose with water and subjecting the mixture to ultrasonic treatment to prepare the cellulose solution.
[0071] In one example, in step b1, the oxidant includes one or more of NaClO2 and KClO2.
[0072] In one example, in step b1, the organic acid includes one or more of formic acid (HCOOH), acetic acid (CH3COOH) and propionic acid (C2H5COOH).
[0073] In one example, in step b1, the temperature for water bath heating can be selected from any value between 70° C. and 80° C. Specifically, in step b1, the temperature for water bath heating includes but is not limited to 72° C., 74° C., 75° C., 76° C., 77° C., 78° C. or 80° C.
[0074] In step b1, wood powder is dissolved in an oxidant and an organic acid solution. The oxidant can oxidize the phenolic hydroxyl groups and aromatic ring structures in the lignin molecules, turning the lignin into a soluble small molecule compound. Therefore, after heating in a water bath, lignin will exist in the supernatant. At this time, removing the supernatant will obtain holocellulose.
[0075] In one example, in step b2, the temperature for water bath heating can be selected from any value between 85° C. and 95° C. Specifically, in step b2, the temperature for water bath heating includes but is not limited to 85° C., 88° C., 89° C., 90° C., 91° C., 92° C., 94° C. or 95° C.
[0076] In step b2, holocellulose includes cellulose and hemicellulose. Under alkaline conditions, hemicellulose is easily decomposed and dissolved. At this time, hemicellulose exists in the supernatant. At this time, removing the supernatant will obtain cellulose.
[0077] In one example, in step b3, the device for ultrasonic treatment is an ultrasonic cell disruptor.
[0078] In one specific example, the method for preparing the aerogel comprises the following steps:
[0079] (1) dissolving wood powder in a solution dispersed with NaClO2 and CH3COOH, heating in a water bath at 70°C to 80°C, washing with water, and removing the supernatant to obtain holocellulose;
[0080] (2) mixing the holocellulose with a KOH aqueous solution, heating the mixture in a water bath at a temperature of 85° C. to 95° C., washing the mixture with water, and removing the supernatant to obtain cellulose;
[0081] (3) mixing the cellulose with water and performing ultrasonic treatment using an ultrasonic cell pulverizer to prepare the cellulose solution;
[0082] (4) pre-freezing the cellulose solution at -80°C to -20°C, and then freeze-drying the solution to prepare a cellulose aerogel;
[0083] (5) The cellulose aerogel is carbonized in an inert gas atmosphere to prepare the carbon aerogel.
[0084] In a third aspect of the present application, a cathode electrode is provided, comprising an electrode substrate and a catalyst supported on the electrode substrate, wherein the catalyst comprises the cathode catalyst described in any example of the first aspect of the present application.
[0085] It is understandable that the material of the electrode substrate can be selected from materials commonly used by those skilled in the art. For example, the material of the electrode substrate includes but is not limited to nickel foam, nickel wire or nickel mesh.
[0086] The present application also provides a method for preparing a cathode electrode, comprising the following steps:
[0087] c1. Mixing the cathode catalyst and the conductive agent in a mass ratio of (7-9):1, adding a binder and a solvent to prepare a slurry;
[0088] c2. The slurry is coated on a cathode substrate, and after drying, pressed into a cathode electrode.
[0089] It can be understood that in step c1, the mass ratio of the cathode catalyst and the conductive agent can be selected from any value between (7~9): 1. Specifically, the mass ratio of the cathode catalyst and the conductive agent includes but is not limited to 7: 1, 7.1: 1, 7.3: 1, 7.4: 1, 7.5: 1, 7.6: 1, 7.7: 1, 7.8: 1, 7.9: 1, 8: 1, 8.1: 1, 8.2: 1, 8.3: 1, 8.5: 1, 8.8: 1, 8.9: 1 or 9: 1; or within the range formed by any two of the above point values as end values.
[0090] It is understandable that in step c1, the selected adhesive may be an adhesive commonly used by those skilled in the art. For example, the types of adhesive include but are not limited to polytetrafluoroethylene, chloroprene, and acrylic acid.
[0091] In step c1, the solvent includes but is not limited to methanol, ethanol or propanol.
[0092] In one example, the cathode electrode is an electrode for hydrogen evolution reaction.
[0093] The cathode catalyst provided by the present application helps to accelerate the electrolysis reaction of water molecules and promote the rate of hydrogen production; at the same time, the cathode catalyst has high durability in the cathode electrode and can maintain catalytic activity for a long time. Further, in the hydrogen evolution reaction, some impurities or pollutants will adhere to the electrode surface, but at this time the cathode catalyst of the present application has good electron transfer performance and can quickly transfer electrons from the electrode to the catalytic active site, which helps the cathode electrode maintain its catalytic activity in the presence of pollutants and reduces the impact of pollutants on electrode performance.
[0094] In a fourth aspect of the present application, a device for producing hydrogen by electrolysis of water is provided, comprising a cathode electrode, an anode electrode and an electrolyte, wherein the cathode electrode and the anode electrode are arranged relatively spaced apart in the electrolyte, the cathode electrode is the cathode electrode described in the third aspect of the present application, and the electrolyte is an alkaline solution with a mass fraction of 25% to 35%.
[0095] The cathode catalyst provided in the present application has excellent stability in an alkaline environment, so it is suitable for electrolysis of alkaline water. Specifically, the electrolyte is an alkaline solution with a mass fraction of 25% to 35%. More specifically, the mass fraction of the alkaline solution includes but is not limited to 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34% or 35%. For example, the alkaline solution includes but is not limited to potassium hydroxide and sodium hydroxide.
[0096] In one example, the water electrolysis hydrogen production system further includes a diaphragm.
[0097] In a fifth aspect of the present application, a hydrogen production system is provided, comprising the water electrolysis hydrogen production device described in the third aspect of the present application.
[0098] In one example, the hydrogen production system includes a water electrolysis hydrogen production device, a gas-liquid separation device and a purification device. The hydrogen production system provided in the present application applies voltage to the water electrolysis hydrogen production device through a power supply to electrolyze the electrolyte in the electrolytic cell cavity to obtain a gas-liquid mixture containing hydrogen, and the gas-liquid mixture containing hydrogen is processed by the gas-liquid separation device and the purification device to obtain high-purity hydrogen.
[0099] Specifically, an alkaline solution is selected as the electrolyte in the present application, wherein a voltage is applied to the water electrolysis hydrogen production device through a power supply, and hydroxide ions undergo oxidation reaction at the anode electrode to produce oxygen. The specific reaction includes: 4OH - - 4e - =O2+2H2O; at the cathode electrode, water molecules gain electrons and undergo a reduction reaction to produce hydrogen and hydroxide ions. At this time, the active components on the cathode electrode can promote the adsorption and desorption of hydrogen, thereby effectively improving the hydrogen evolution reaction. The specific reactions include: 2H2O+2e -= H2+2OH - However, the H2 produced in the cathode will also carry some liquid and a very small amount of oxygen, so what is obtained on the cathode side is a gas-liquid mixture containing hydrogen; the gas-liquid mixture containing hydrogen is further processed by a gas-liquid separation device and a purification device to obtain high-purity hydrogen.
[0100] The following further specific examples are provided to explain the present application in detail. It should also be understood that the following examples are only used to further explain the present application and cannot be understood as limiting the scope of protection of the present application. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present application belong to the scope of protection of the present application. The specific process parameters of the following embodiments are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not necessarily limited to the specific values of the embodiments below.
[0101] Preparation Example 1
[0102] Preparation of carbon aerogel:
[0103] (1) dissolving wood powder in a solution dispersed with NaClO2 and CH3COOH (the mass percentage of NaClO2 in the solution is 50% and the mass percentage of CH3COOH is 50%), heating the solution in a water bath at 75°C for 5 h, washing the solution with water, and removing the supernatant to remove lignin from the wood powder to obtain holocellulose;
[0104] (2) mixing the holocellulose with a KOH aqueous solution (the mass percentage of KOH in the KOH aqueous solution is 30%), heating the mixture in a water bath at a temperature of 90° C., washing the mixture with water, and removing the supernatant to remove the hemicellulose, thereby obtaining cellulose;
[0105] (3) mixing the cellulose with water, and performing ultrasonic treatment for 30 minutes using an ultrasonic cell crusher to prepare the cellulose solution (the mass fraction of cellulose in the cellulose solution is 0.8%);
[0106] (4) pre-freezing the cellulose solution at -80°C to -20°C for 24 hours, and then freeze-drying it for 3 days to prepare cellulose aerogel;
[0107] (5) The cellulose aerogel is carbonized in a N2 atmosphere (the process parameters of the carbonization treatment include: heating to 900°C at a heating rate of 3°C / min, keeping the temperature for 2 hours, and then naturally cooling to room temperature) to prepare the carbon aerogel.
[0108] Example 1
[0109] Preparation of cathode catalyst:
[0110] (1) MnC4H6O4·4H2O and CoCl2·6H2O are dissolved in deionized water at a molar ratio of 1:1 to prepare a mixed solution, wherein the mass percentage of the metal element in the mixed solution is 6wt%;
[0111] (2) The mixed solution was stirred for 30 min to form a uniform solution, and then the mixed solution and the carbon aerogel obtained in Preparation Example 1 were mixed at a mass ratio of 20:1, and transferred to a reactor, heated at 170°C for 8 h, and taken out after cooling to room temperature. After washing with ethanol three times, it was dried at 60°C for 12 h to obtain a cathode catalyst.
[0112] Preparation of cathode electrode:
[0113] Grind the cathode catalyst in an agate mortar for 30 minutes, take 15 mg of cathode catalyst powder and 1.875 mg of acetylene black powder, mix and grind again, then add 1.5 mg of polytetrafluoroethylene PTFE and an appropriate amount of ethanol, stir to mix into a slurry, apply it on the nickel mesh, dry at 100 ° C for 10 hours, and then press into a cathode electrode at a pressure of 10 MPa.
[0114] Electrolysis hydrogen production performance test:
[0115] An electrochemical workstation three-electrode system was used, with the prepared cathode electrode as the working electrode, Hg / HgO as the reference electrode, and Pt sheet electrode as the counter electrode. A KOH solution with a mass fraction of 30 wt% was selected as the electrolyte to test the hydrogen evolution stability of the cathode electrode at room temperature.
[0116] The operating time-voltage curve of the cathode electrode of Example 1 obtained by testing is as follows: Figure 1 As shown, the voltage drop rate after 10 hours of chronopotentiometry is shown in Table 1.
[0117] Example 2
[0118] Example 2 is basically the same as Example 1, the main difference being that the preparation step (1) of the cathode catalyst in Example 2 is different from that in Example 1. The preparation step (1) of Example 2 is:
[0119] MnC4H6O4·4H2O was dissolved in deionized water to prepare a mixed solution, in which the mass percentage of the metal element in the mixed solution was 6 wt %.
[0120] The voltage drop rate of the cathode electrode of Example 2 after 10 hours of chronopotentiometry is shown in Table 1.
[0121] Example 3
[0122] Example 3 is basically the same as Example 1, the main difference being that the preparation step (1) of the cathode catalyst in Example 3 is different from that in Example 1. The preparation step (1) of Example 3 is:
[0123] (1) MnC4H6O4·4H2O and CoCl2·6H2O were dissolved in deionized water at a molar ratio of 1:1.5 to prepare a mixed solution, wherein the mass percentage of the metal element in the mixed solution was 6 wt %.
[0124] The voltage drop rate of the cathode electrode of Example 3 after 10 hours of chronopotentiometry is shown in Table 1.
[0125] Example 4
[0126] Example 4 is basically the same as Example 1, with the main difference being that in the electrolytic hydrogen production performance test of Example 4, the selected electrolyte is a KOH solution with a mass fraction of 25 wt%.
[0127] The voltage drop rate of the cathode electrode of Example 4 after 10 hours of chronopotentiometry is shown in Table 1.
[0128] Example 5
[0129] Example 5 is basically the same as Example 1, the main difference being that the preparation step (1) of the cathode catalyst in Example 5 is different from that in Example 1. The preparation step (1) of the cathode catalyst in Example 5 is:
[0130] FeCl3·6H2O and NiCl2·6H2O were dissolved in deionized water at a molar ratio of 1:1 to prepare a mixed solution, wherein the mass percentage of the metal element in the mixed solution was 6 wt %.
[0131] The voltage drop rate of the cathode electrode of Example 5 after 10 hours of chronopotentiometry is shown in Table 1.
[0132] Example 6
[0133] Example 6 is basically the same as Example 1, the main difference being that the preparation step (2) of the cathode catalyst in Example 6 is different from that in Example 1, wherein the preparation step of the cathode catalyst in Example 6 is:
[0134] The mixed solution was stirred for 30 min to form a uniform solution, and then the mixed solution and carbon aerogel were transferred to a reactor at a mass ratio of 20:1, heated at 170 °C for 8 h, and taken out after cooling to room temperature. After washing three times with ethanol, it was dried at 60 °C for 12 h to obtain a cathode catalyst.
[0135] The carbon aerogel selected in Example 6 is prepared by the following steps:
[0136] (1) Add 5 g of starch to 10 mL of water and mix thoroughly to prepare a starch-water mixture; heat 300 mL of 5% by mass ferric chloride solution to 100°C, then pour the starch-water mixture into the solution to prepare a gel solution, and cool the solution to obtain a starch hydrogel.
[0137] (2) After freezing the starch hydrogel at -80°C for 12 hours, vacuum drying was performed at 0°C for 24 hours to obtain freeze-dried starch aerogel. The freeze-dried starch aerogel was placed in a carbonization furnace for carbonization treatment. The carbonization process included: heating to 700°C at a heating rate of 4°C / min and maintaining for 2 hours; and naturally cooling to room temperature to obtain carbon aerogel.
[0138] The voltage drop rate of the cathode electrode of Example 6 after 10 hours of chronopotentiometry is shown in Table 1.
[0139] Comparative Example 1
[0140] Comparative Example 1 is substantially the same as Example 1, with the main difference being that carbon fiber is used in the preparation (2) of the cathode catalyst in Comparative Example 1 to replace the carbon aerogel in step (2) of Example 1.
[0141] The voltage drop rate of the cathode electrode of Comparative Example 1 after 10 hours of chronopotentiometry is shown in Table 1.
[0142] Comparative Example 2
[0143] Comparative Example 2 is basically the same as Example 1, with the main difference being that the preparation (1) of the cathode catalyst in Comparative Example 2 is different from that in Example 1. The preparation step (1) of Comparative Example 2 is:
[0144] (1) Nano-sheet MoS2 is dissolved in deionized water to prepare a mixed solution, wherein the mass percentage of the metal element in the mixed solution is 6 wt %.
[0145] The voltage drop rate of the cathode electrode of Comparative Example 1 after 10 hours of chronopotentiometry is shown in Table 1.
[0146] In the cathode catalyst prepared in Example 1, the carbon aerogel carrier has a 3D pore structure, and the pore structure size is about 1 μm to 3 μm. Figure 1 is the operating time-voltage curve of the cathode electrode of Example 1, Figure 1 It can be seen that the voltage drop value of the cathode electrode of Example 1 after 10 hours of chronopotentiometry is very small, with a voltage drop rate of 6%, and its initial voltage is basically retained; this shows that the cathode catalyst has good hydrogen evolution stability.
[0147] Table 1
[0148]
[0149] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0150] The above-described embodiments only express several implementation methods of the present application, which is convenient for understanding the technical solution of the present application in detail, but it cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description can be used to interpret the content of the claims.
Claims
1. A cathode catalyst, characterized in that The invention comprises a carbon aerogel and an active component supported on the carbon aerogel, wherein the active component comprises one or more of Fe, Co, Ni and Mn elements.
2. The cathode catalyst according to claim 1, characterized in that The active components include at least two of Fe, Co, Ni and Mn.
3. The cathode catalyst according to claim 2, characterized in that The active components include Mn and Co; or The active components include Fe and Ni.
4. The cathode catalyst according to claim 3, characterized in that In the active component, the molar ratio of the Mn element to the Co element is 1:(0.5-2); or, In the active component, the molar ratio of the Fe element to the Ni element is 1:(0.5-2).
5. The cathode catalyst according to claim 4, characterized in that In the active component, the molar ratio of the Mn element to the Co element is 1:(0.5-2).
6. The cathode catalyst according to any one of claims 1 to 5, characterized in that In the cathode catalyst, the mass ratio of the metal element included in the active component to the carbon aerogel is (1-1.5):
1.
7. The cathode catalyst according to any one of claims 1 to 5, characterized in that The carbon aerogel is a cellulose-based carbon aerogel.
8. A method for preparing a cathode catalyst according to any one of claims 1 to 7, characterized in that: The following steps are involved: mixing an active precursor material and the carbon aerogel in a solution to prepare a mixed solution; subjecting the mixed solution to a hydrothermal reaction to prepare the cathode catalyst; The active precursor material includes one or more of iron salt, cobalt salt, nickel salt and manganese salt.
9. The method for preparing a cathode catalyst according to claim 8, wherein: The active precursor material includes at least two of an iron salt, a cobalt salt, a nickel salt, and a manganese salt.
10. The method for preparing a cathode catalyst according to claim 8, wherein: The active precursor material comprises manganese acetate tetrahydrate and cobalt chloride hexahydrate; or, The active precursor materials include ferric chloride hexahydrate and nickel chloride hexahydrate.
11. The method for preparing a cathode catalyst according to claim 10, wherein: The molar ratio of the manganese acetate tetrahydrate to the cobalt chloride hexahydrate in the active precursor material is 1:(0.5-2); or, The molar ratio of the ferric chloride hexahydrate to the nickel chloride hexahydrate in the active precursor material is 1:(0.5-2).
12. The method for preparing a cathode catalyst according to claim 11, wherein: The molar ratio of the manganese acetate tetrahydrate to the cobalt chloride hexahydrate in the active precursor material is 1:(0.5-2).
13. The method for preparing a cathode catalyst according to any one of claims 8 to 12, characterized in that: The mass ratio of the metal element included in the active precursor material to the carbon aerogel is (1-1.5):
1.
14. The method for preparing a cathode catalyst according to any one of claims 8 to 12, wherein: The process parameters of the hydrothermal reaction include: a reaction temperature of 170°C to 180°C.
15. The method for preparing a cathode catalyst according to any one of claims 8 to 12, characterized in that: The preparation method of the carbon aerogel comprises the following steps: The cellulose solution was pre-frozen at -80°C to -20°C and then freeze-dried to prepare cellulose aerogel. The cellulose aerogel is carbonized in an inert gas atmosphere to prepare the carbon aerogel.
16. A cathode electrode, characterized in that: The invention comprises an electrode substrate and a catalyst supported on the electrode substrate, wherein the catalyst comprises the cathode catalyst according to any one of claims 1 to 7.
17. A hydrogen production device by electrolysis of water, characterized in that: It comprises a cathode electrode, an anode electrode and an electrolyte, wherein the cathode electrode and the anode electrode are arranged in the electrolyte with relative spacing, the cathode electrode is the cathode electrode according to claim 16, and the electrolyte is an alkaline solution with a mass fraction of 25% to 35%.
18. A hydrogen production system, characterized in that: Including the water electrolysis hydrogen production device as described in claim 17.