Electrode for hydrogen evolution by electrolyzing water, preparation method of electrode and application of electrode in water electrolysis device

Abstract

The invention discloses an electrode for hydrogen evolution by electrolyzing water, which is characterized in that carbon cloth is used as a substrate, and micron-sized linear cobalt-based metal oxide derived from N, N-dimethylformamide complex grows on the surface of the carbon cloth. The invention also provides a preparation method of the electrode for hydrogen evolution by water electrolysis. The electrode provided by the invention has a micron-sized linear structure, so that regulation and control on a catalyst-electrolyte interface microenvironment are enhanced, and interface water molecules in an electrolyte, protons separated from a reaction intermediate and product oxygen molecules can be promoted to be quickly transferred and conveyed; high catalytic activity and current stability can be maintained in a severe acid environment; due to the formation of the N, N-dimethylformamide complex, the electronic structure of the cobalt-based metal oxide is optimized, the catalyst-electrolyte interface is improved, and the intrinsic activity and stability are improved; the electrode is hopeful to overcome severe conditions in an acid environment, and has important practical significance for realizing large-scale development of preparing green hydrogen by electrolyzing water.

Description

Technical Field

[0001] This invention belongs to the field of materials technology, specifically relating to an electrode for hydrogen evolution through water electrolysis, and further relating to an electrode containing a cobalt-based metal oxide catalyst derived from an N,N-dimethylformamide complex, its preparation method, and its application in a water electrolysis device. Background Technology

[0002] Against the backdrop of energy transition, hydrogen's potential as a clean energy source is increasingly prominent, and efficient hydrogen production technology is crucial. Proton exchange membrane electrolysis (PEMWE) has become a promising hydrogen production technology due to its highly efficient proton transport capabilities. However, the oxygen evolution reaction (OER) at its anode poses a severe challenge to the catalyst under strongly acidic conditions. In acidic OER, the rapid accumulation of protons on the catalyst surface accelerates the depletion of electrons at active metal sites, leading to irreversible over-oxidation or even dissolution and deactivation of the metal. Traditional strategies, such as doping and hybridization, mainly focus on regulating the bulk electronic structure of the catalyst to optimize the adsorption energy of intermediates, but this often overlooks the critical role of the catalyst-electrolyte interface, the actual site of the reaction. Recent studies have found that the interfacial microenvironment has a decisive influence on reaction efficiency. Combining the optimization of the intrinsic activity of the catalyst with the precise regulation of the interfacial microenvironment is an effective way to overcome the kinetic bottleneck of acidic OER.

[0003] Besides the intrinsic activity of the catalyst and the interfacial microenvironment, the behavior of bubbles generated during oxygen evolution is a core but often overlooked factor affecting the efficiency and stability of PEMWE (Protocol Electrode Evolution). If oxygen bubbles generated on the electrode surface cannot desorb in time, they will form a gas capping layer, physically shielding active sites and increasing system resistance. More seriously, the slow growth and desorption of bubbles can generate enormous tensile stress on the catalyst particles, directly leading to pulverization and detachment of the catalyst layer. Therefore, efficient bubble management is crucial for maintaining the macroscopic stability of the catalyst. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the main objective of this invention is to provide an electrode with high catalytic activity and long-term stability for hydrogen evolution in water electrolysis.

[0005] The present invention also provides a method for preparing the electrode for hydrogen evolution by water electrolysis.

[0006] The purpose of this invention is to also provide a water electrolysis device containing the aforementioned water electrolysis hydrogen evolution electrode.

[0007] The objective of this invention is achieved through the following technical solution: An electrode for hydrogen evolution through water electrolysis is based on carbon cloth, on which micron-sized linear N,N-dimethylformamide complex-derived cobalt-based metal oxides are grown.

[0008] As part of the same inventive concept, the present invention also provides a method for preparing an electrode for hydrogen evolution in water electrolysis, comprising the following steps: 1) Carbon cloth is subjected to hydrothermal treatment in a cobalt-containing mixed solution, followed by calcination to obtain cobalt-based metal oxides; 2) The prepared cobalt-based metal oxide was electrochemically activated in an N,N-dimethylformamide solution to obtain an electrode of cobalt-based metal oxide derived from an N,N-dimethylformamide complex.

[0009] N,N-dimethylformamide is a polar aprotic solvent of DMF, and its carbonyl oxygen atom has a strong coordination ability. Under the action of an electric field, when the cobalt atoms on the surface are oxidized to a high valence state, their chemical bonds become shorter and unstable. DMF molecules will adsorb and coordinate to these high-valence cobalt sites to form Co-DMF surface complex intermediates.

[0010] In some specific embodiments, the cobalt-containing mixed solution is a mixed solution composed of cobalt salt, fluoride salt and urea.

[0011] This process utilizes the slow decomposition of urea at high temperatures to release ammonia and CO2, providing an alkaline environment; while ammonium fluoride serves as a key morphology control agent. - Ions can selectively adsorb onto specific surfaces of crystals, inhibiting their lateral growth and inducing them to grow into linear shapes along the axial direction.

[0012] The cobalt salt is one or more of cobalt nitrate, cobalt chloride, and cobalt sulfate.

[0013] The fluoride salts include, but are not limited to, ammonium fluoride; The molar ratio of the cobalt salt, fluoride salt, and urea is 0.5-1.5:1.5-2.5:4-6; In some specific embodiments, the carbon arrangement in step 1) is further subjected to ultrasonic cleaning in 0.05-1.5 mol / L sulfuric acid and 75-95% ethanol for 10-30 minutes in sequence.

[0014] In some specific embodiments, the thickness of the carbon cloth in step 1) is 0.3 ~ 1 mm.

[0015] Furthermore, the thickness of the carbon cloth is 0.3mm, 0.4mm, 0.6mm, 0.8mm, or 1mm.

[0016] In some specific embodiments, the concentration of the cobalt salt solution is 0.5-1.5 mol / L.

[0017] In some specific embodiments, the cobalt salt mentioned in step 2) is one or more of cobalt nitrate, cobalt chloride, and cobalt sulfate.

[0018] In some specific embodiments, the hydrothermal treatment process conditions in step 2) are: maintaining the reaction at a hydrothermal temperature of 120~180℃ for 4~12 hours.

[0019] Furthermore, the specific temperature of the hydrothermal treatment in step 2) can be 120 ℃, 140 ℃, 160 ℃, or 180 ℃; the heating time can be 4 hours, 8 hours, or 12 hours.

[0020] In some specific embodiments, the calcination process conditions in step 2) are: calcination at 250-350°C for 1.5-2.5 hours in an air atmosphere.

[0021] In some specific embodiments, in step 3), the activation treatment of cobalt-based metal oxides in N,N-dimethylformamide is achieved by a constant voltage method.

[0022] In some specific embodiments, the N,N-dimethylformamide solution is AR, ≥99.5%; the activation voltage range is 1.8~2.4 V vs. SHE, and the activation time is 5~20 minutes.

[0023] In some specific embodiments, the process further includes vacuum drying of the cobalt-based metal oxide derived from the N,N-dimethylformamide complex prepared in step 3).

[0024] Furthermore, the process conditions for the vacuum drying treatment are: drying at a temperature of 30-80℃ for 2-8 hours.

[0025] As part of the same inventive concept, the present invention also provides a water electrolysis device comprising the aforementioned electrodes for hydrogen evolution through water electrolysis.

[0026] Compared with the prior art, the present invention has at least the following advantages: 1) The electrode for hydrogen evolution by water electrolysis provided by the present invention uses carbon cloth as a substrate, on which micron-sized linear N,N-dimethylformamide complex-derived cobalt-based metal oxides are grown. The micron-sized linear structure enhances the regulation of the catalyst-electrolyte interface microenvironment, which can promote the rapid transfer and transport of interfacial water molecules, protons released from reaction intermediates, and product oxygen molecules in the electrolyte, so as to maintain high catalytic activity and current stability in harsh acidic environments. The formation of N,N-dimethylformamide complex optimizes the electronic structure of cobalt-based metal oxides, improves the catalyst-electrolyte interface, and enhances intrinsic activity and stability.

[0027] 2) The preparation method provided by the present invention involves hydrothermally treating carbon cloth in a cobalt salt solution, followed by calcination, and then electrochemically activating the calcined product in an N,N-dimethylformamide solution to obtain a cobalt-based metal oxide derived from an N,N-dimethylformamide complex with a micron-scale linear structure grown on the surface of the carbon cloth. This preparation process is simple and environmentally friendly, requires no complex equipment or expensive raw materials, and is suitable for large-scale production.

[0028] 3) The electrode containing cobalt-based metal oxides derived from N,N-dimethylformamide complexes provided by this invention is expected to overcome the harsh conditions under acidic environments and has important practical significance for the large-scale development of water electrolysis to produce green hydrogen. Attached Figure Description

[0029] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.

[0030] Figure 1 Raman blotting of the electrode containing a cobalt-based metal oxide derived from an N,N-dimethylformamide complex prepared in Example 1; Figure 2 SEM image of cobalt-based metal oxides containing N,N-dimethylformamide complexes prepared for Example 1; Figure 3 SEM-Mapping image of the electrode containing cobalt-based metal oxides derived from N,N-dimethylformamide complex prepared in Example 1; Figure 4 The LSV curves of the electrodes of the carbon cloth of Example 1, the cobalt-based metal oxide prepared in step 2), and the cobalt-based metal oxide derived from the N,N-dimethylformamide complex prepared in step 4), and their comparative samples are shown. Detailed Implementation

[0031] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0032] It should be noted that, in the absence of conflict, the following embodiments and features can be combined with each other; and, based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0033] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0034] In the following examples, N,N-dimethylformamide was of analytical grade and had a concentration ≥99.5%; This invention provides a method for preparing an electrode for hydrogen evolution in water electrolysis, comprising the following steps: 1) Clean the carbon array sequentially with 0.05-1.5 mol / L sulfuric acid and 75-95% ethanol using ultrasonic cleaning for 10-30 minutes. 2) Carbon cloth is placed in a mixed solution of cobalt salt, fluoride salt and urea in a molar ratio of 0.5-1.5:1.5-2.5:4-6 and the reaction is maintained at a hydrothermal temperature of 120-180℃ for 4-12 hours; then the hydrothermal reaction product is calcined in air at a temperature of 250-350℃ for 1.5-2.5 hours to obtain cobalt-based metal oxide; 3) The prepared cobalt-based metal oxide was subjected to constant voltage treatment in N,N-dimethylformamide solution, with a given voltage of 1.8-2.4 V vs. SHE (relative to the potential of the calomel electrode), for 5-20 minutes; 4) After the reaction is complete, the activated product is washed and dried in a vacuum drying oven at 30-80℃ for 2-8 hours to obtain the electrode of cobalt-based metal oxide derived from N,N-dimethylformamide complex, which is used for hydrogen evolution by water electrolysis.

[0035] In the preparation of the electrode for hydrogen evolution by water electrolysis, the self-grown catalyst structure is more tightly and firmly bonded to the self-supporting substrate. Moreover, the micron-scale linear structure can provide discontinuous three-phase contact lines, effectively reducing the adhesion and final size of bubbles and accelerating bubble discharge.

[0036] Example 1 This embodiment provides a method for preparing an electrode for hydrogen evolution in water electrolysis, comprising the following steps: The carbon cloth was ultrasonically cleaned for 30 minutes in sequence with 0.5 mol / L sulfuric acid and 95% ethanol, and then dried in a vacuum drying oven. Weigh 1 mmol of cobalt nitrate hexahydrate, 2 mmol of ammonium fluoride and 5 mmol of urea and dissolve them thoroughly in a polytetrafluoroethylene reactor containing 50 mL of deionized water to obtain a mixed solution; immerse the carbon cloth pretreated in step 1) into the aforementioned mixed solution, assemble the reactor, heat to 160 °C and maintain for 8 hours; after the reaction is complete, rinse the product, place it in a muffle furnace with air in circulation, heat to 300 °C and maintain for 2 hours to obtain cobalt-based metal oxide; Using a standard three-electrode system, the prepared precursor was subjected to constant voltage treatment in N,N-dimethylformamide (AR, ≥99.5%) at a given voltage of 2.0 V vs. SHE (relative to the potential of the calomel electrode) for 15 minutes. After the reaction is complete, the activated product is washed and dried in a vacuum drying oven at 60°C for 4 hours to obtain the electrode of cobalt-based metal oxide derived from N,N-dimethylformamide complex.

[0037] Example 2 This embodiment provides a method for preparing an electrode for hydrogen evolution in water electrolysis, comprising the following steps: 1) Clean the carbon cloth with 0.5 mol / L sulfuric acid and 95% ethanol in sequence by ultrasonic cleaning for 30 minutes, and then dry it in a vacuum drying oven; 2) Weigh 1 mmol of cobalt chloride hexahydrate, 2 mmol of ammonium fluoride and 5 mmol of urea and dissolve them thoroughly in a polytetrafluoroethylene reactor containing 50 mL of deionized water to obtain a mixed solution; immerse the carbon cloth pretreated in step 1) into the aforementioned mixed solution, assemble the reactor, heat to 120 °C and maintain for 12 hours; after the reaction is complete, rinse the product, place it in a muffle furnace with air in circulation, heat to 300 °C and maintain for 2 hours to obtain cobalt-based metal oxide; 3) Using a standard three-electrode system, the prepared precursor was subjected to constant voltage treatment in N,N-dimethylformamide (AR, ≥99.5%), with a given voltage of 2.0 V vs. SHE (relative to the potential of the calomel electrode); activation was performed for 5 minutes. 4) After the reaction is complete, the product is washed and dried in a vacuum drying oven at 80°C for 2 hours to obtain the electrode of cobalt-based metal oxide derived from N,N-dimethylformamide complex.

[0038] Example 3 This embodiment provides a method for preparing an electrode for hydrogen evolution in water electrolysis, comprising the following steps: 1) Clean the carbon cloth with 0.5 mol / L sulfuric acid and 95% ethanol in sequence by ultrasonic cleaning for 30 minutes, and then dry it in a vacuum drying oven; 2) Weigh 1 mmol of cobalt sulfate heptahydrate, 2 mmol of ammonium fluoride and 5 mmol of urea and dissolve them thoroughly in a polytetrafluoroethylene reactor containing 50 mL of deionized water to obtain a mixed solution; immerse the carbon cloth pretreated in step 1) into the aforementioned mixed solution, assemble the reactor, heat to 180 °C and maintain for 4 hours; after the reaction is complete, rinse the product, place it in a muffle furnace with air in circulation, heat to 300 °C and maintain for 2 hours to obtain cobalt-based metal oxide; 3) Using a standard three-electrode system, the prepared precursor was subjected to constant voltage treatment in N,N-dimethylformamide (AR, ≥99.5%), with a given voltage of 2.0 V vs. SHE (relative to the potential of the calomel electrode), for 20 minutes. 4) After the reaction is complete, the product is washed and dried in a vacuum drying oven at 30°C for 8 hours to obtain the electrode of cobalt-based metal oxide derived from N,N-dimethylformamide complex.

[0039] Performance testing: 1) Structural assessment: This application uses Example 1 as an example to perform Raman characterization on the cobalt-based metal oxide derived from the prepared N,N-dimethylformamide complex. The results are as follows: Figure 1 As shown in the figure, compared with cobalt-based metal oxides, the product has characteristic peaks belonging to the metal N,N-dimethylformamide complex, which proves the successful preparation of cobalt-based metal oxides derived from N,N-dimethylformamide complex; 2) Morphology and elemental distribution testing This application uses Example 1 as an example to perform morphology testing on the electrode of cobalt-based metal oxide derived from the prepared N,N-dimethylformamide complex. The results are as follows: Figure 2 As shown, the SEM images reveal that the carbon cloth's skeletal structure surface forms micron-scale linear structures with lengths ranging from 3 to 6 micrometers.

[0040] The micron-scale linear structure formed on the electrode surface promotes rapid bubble desorption, reduces catalyst pulverization and shedding, and achieves long-term stability.

[0041] Meanwhile, taking Example 1 as an example, this application tests the elemental distribution in the cobalt-based metal oxide derived from the prepared N,N-dimethylformamide complex, and the results are as follows: Figure 3 As shown, Figure 3 The SEM-Mapping image of cobalt-based metal oxides derived from N,N-dimethylformamide complexes shows the uniform distribution of elements Co, N, C, and O.

[0042] 3) Electrochemical performance testing Test Method: At room temperature, the oxygen evolution performance of the electrode samples prepared in Example 1 was tested using a three-electrode system in 0.1 mol / L HClO4 solution on a Gamry Reference 3000 electrochemical workstation. The Pt sheet electrode was used as the counter electrode, the calomel electrode as the reference electrode, and the prepared electrode as the working electrode. Linear sweep voltammetry (LSV) curves were obtained by scanning at a rate of 5 mV / s. Results are as follows: Figure 4 As shown in Table 1: Table 1. Electrochemical oxygen evolution performance of the products prepared in each step of Example 1 of this invention. The carbon cloth in Table 1 is the carbon cloth without pretreatment in the embodiments of this application; The cobalt-based metal oxide (comparative sample) is a cobalt-based metal oxide prepared by a traditional method. The specific preparation method includes the following steps: 1) The carbon cloth is ultrasonically cleaned for 30 minutes with 0.5 mol / L sulfuric acid and 95% ethanol in sequence, and then placed in a vacuum drying oven to dry. 2) Weigh 0.3 ml of ammonia water and 0.05 mol of cobalt chloride hexahydrate and dissolve them thoroughly in a polytetrafluoroethylene reactor containing 50 mL of deionized water to obtain a mixed solution; immerse the acid-washed carbon cloth in the above mixed solution, assemble the reactor, heat to 160 °C and maintain for 8 hours; after the reaction is complete, rinse the product, place it in a muffle furnace with air in circulation, heat to 300 °C and maintain for 2 hours to obtain cobalt-based metal oxide; From Table 1 and Figure 4 The results show that the cobalt-based metal oxides derived from the N,N-dimethylformamide complex prepared in this application exhibit excellent oxygen evolution performance, requiring only 285 mV overpotential to provide 100 mA / cm². 2 Its current density is far superior to that of traditional cobalt-based metal oxides (432 mV) and carbon cloth (510 mV).

[0043] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. 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 therein. Such 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, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. An electrode for hydrogen evolution through water electrolysis, characterized in that, Using carbon cloth as a substrate, micron-sized linear N,N-dimethylformamide complex-derived cobalt-based metal oxides are grown on the surface of the carbon cloth.

2. A method for preparing an electrode for hydrogen evolution in water electrolysis according to claim 1, characterized in that, Includes the following steps: 1) Carbon cloth is subjected to hydrothermal treatment in a cobalt-containing mixed solution, followed by calcination to obtain cobalt-based metal oxides; 2) The prepared cobalt-based metal oxide is electrochemically activated in an N,N-dimethylformamide solution to obtain an electrode containing a cobalt-based metal oxide derived from an N,N-dimethylformamide complex.

3. The method for preparing an electrode for hydrogen evolution in water electrolysis according to claim 1, characterized in that, The cobalt-containing mixed solution mentioned in step 2) is a mixed solution composed of cobalt salt, fluoride salt and urea.

4. The method for preparing an electrode for hydrogen evolution in water electrolysis according to claim 3, characterized in that, The cobalt salt is one or more of cobalt nitrate, cobalt chloride, and cobalt sulfate; the fluoride salt includes, but is not limited to, ammonium fluoride; the molar ratio of the cobalt salt, fluoride salt, and urea is 0.5-1.5:1.5-2.5:4-6.

5. The method for preparing an electrode for hydrogen evolution in water electrolysis according to claim 4, characterized in that, The hydrothermal treatment process conditions described in step 2) are: maintaining the reaction at a hydrothermal temperature of 120~180℃ for 4~12 hours.

6. The method for preparing an electrode for hydrogen evolution in water electrolysis according to claim 5, characterized in that, The calcination process conditions described in step 2) are: calcination at 250-350℃ for 1.5-2.5 hours in an air atmosphere.

7. The method for preparing an electrode for hydrogen evolution in water electrolysis according to claim 6, characterized in that, In step 3), the activation treatment of cobalt-based metal oxides in N,N-dimethylformamide is achieved by constant voltage method.

8. The method for preparing an electrode for hydrogen evolution in water electrolysis according to claim 7, characterized in that, The N,N-dimethylformamide solution is AR, ≥99.5%; the activation voltage range is 1.8~2.4 V vs. SHE, and the activation time is 5~20 minutes.

9. The method for preparing an electrode for hydrogen evolution in water electrolysis according to claim 1, characterized in that, It also includes vacuum drying of the cobalt-based metal oxide derived from the N,N-dimethylformamide complex prepared in step 3).

10. A water electrolysis apparatus comprising the electrode for hydrogen evolution by electrolysis of water as described in claim 1 or the electrode for hydrogen evolution of water prepared by any one of the preparation methods in claims 2-9.

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