Iron-cobalt bimetallic oxyhydroxide as well as preparation method and application thereof
By designing a needle-shaped nanostructured iron-cobalt bimetallic hydroxyoxide catalyst, the existing catalysts have solved the problems of high cost, poor stability and low catalytic activity in the urea oxidation coupled hydrogen production technology, and achieved efficient and economical urea oxidation efficiency.
Patent Information
- Application Number
- CN202510303136.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-14
- Publication Date
- 2025-05-30
AI Technical Summary
The existing catalysts have problems such as high cost, poor stability, low catalytic activity and low oxidation efficiency in the urea oxidation coupled hydrogen production technology, which limits the industrial application of this technology.
A catalyst with a needle-shaped nanostructure was prepared by dissolving iron nitrate nitrate and cobalt nitrate hexahydrate in water, adding ammonium fluoride and urea, and then carrying out hydrothermal reaction.
The catalyst has excellent stability and catalytic activity, can significantly improve the urea oxidation efficiency, reduce the catalyst cost, and is suitable for industrial production and application.
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Figure CN120060896A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of hydrogen production by electrolyzing water. Specifically, it relates to an iron-cobalt bimetallic hydroxide oxide and its preparation method and application. Background Art
[0002] In the context of the profound adjustment of the global energy structure and the high attention paid to environmental sustainability, hydrogen energy has become the research focus in the energy field and an important direction for future development due to its excellent physical and chemical properties, including high energy density, pollution-free reaction products, and renewability. However, at the current stage, the large-scale production of hydrogen energy faces many challenges. Among them, the traditional method of hydrogen production by electrolyzing water has a high theoretical voltage and high energy consumption, which has become one of the key bottlenecks restricting its wide application. Therefore, it is of great significance to actively explore efficient and economical hydrogen production strategies.
[0003] As a highly potential new hydrogen production technology path, hydrogen production by coupling urea oxidation shows significant advantages in terms of resource utilization and environmental protection. Urea, as a nitrogen-containing organic compound widely present in nature, is abundant in agricultural production, domestic sewage, and industrial wastewater. As a hydrogen production raw material, it can not only achieve the efficient recovery and recycling of resources but also couple hydrogen production through the urea oxidation reaction, effectively avoiding environmental negative effects such as water eutrophication caused by urea emissions, which meets the requirements of green chemistry and sustainable development.
[0004] However, the efficient production of hydrogen by coupling urea oxidation highly depends on high-performance catalysts and requires precise regulation of the electronic structure of the catalysts to improve the stability and activity of the reaction. Currently, the catalysts applied in this field have many limitations. Although noble metal-based catalysts (such as ruthenium, palladium, etc.) show excellent catalytic activity, their rarity and high cost greatly limit the feasibility of large-scale industrial applications. In contrast, non-noble metal catalysts often perform poorly in key performance indicators such as catalytic activity, long-term stability, and selectivity for the urea oxidation reaction, resulting in low conversion efficiency of the reaction, limited hydrogen production rate, and easy occurrence of side reactions, seriously hindering the further development of the hydrogen production technology by coupling urea oxidation.
[0005] Therefore, it is necessary to design an iron-cobalt bimetallic hydroxide oxide catalyst to solve the problems of high cost, inapplicability to industrial production, poor stability, low catalytic activity, and low oxidation efficiency of existing catalysts. Summary of the Invention
[0006] In view of this, the present invention proposes an iron-cobalt bimetallic hydroxide oxide catalyst, aiming to solve the problems of inapplicability to industrial production, poor stability, and low catalytic activity of existing catalysts.
[0007] In one aspect, the present invention provides a method for preparing an iron-cobalt bimetallic oxyhydroxide catalyst, comprising the following steps:
[0008] Pre-treating the nickel foam and setting it aside to obtain the nickel foam for use;
[0009] Dissolving ferric nitrate nonahydrate and cobalt nitrate hexahydrate in water, and performing a first stirring until they are completely dissolved, to obtain a first mixed solution;
[0010] adding ammonium fluoride to the first mixed solution, performing a second stirring until it is completely dissolved, and then adding urea and performing a third stirring to obtain a second mixed solution;
[0011] The second mixed solution is mixed with the nickel foam to be used, and a hydrothermal reaction is carried out to obtain an iron-cobalt bimetallic oxyhydroxide.
[0012] Furthermore, the pretreatment is specifically as follows: the nickel foam is first immersed in 3 mol / L hydrochloric acid for 15 minutes and then washed with water, and then the nickel foam is ultrasonically treated in anhydrous ethanol and water for 5 minutes respectively, and then washed with water three times and then taken out and dried naturally.
[0013] Furthermore, the rotation speeds of the first stirring, the second stirring and the third stirring are 400-600 rpm; and the time of the third stirring is 5-10 minutes.
[0014] Further, the molar concentration of the ferric nitrate nonahydrate is 1-2 mM; the molar concentration of the cobalt nitrate hexahydrate is 0.3-1 mM; the molar concentration of urea is 1-10 mM; the molar concentration of ammonium fluoride is 1-3 mM;
[0015] Furthermore, the temperature for dissolving the ferric nitrate nonahydrate and the cobalt nitrate hexahydrate is 40-50°C.
[0016] Furthermore, the hydrothermal reaction is specifically to heat the temperature to 100-120° C. at a first heating rate, maintain for 2-3 hours, and then heat the temperature to 140-160° C. at a second heating rate, maintain for 6-9 hours.
[0017] Furthermore, the first heating rate is 10-15°C / min; the second heating rate is 3-5°C / min.
[0018] Furthermore, after the hydrothermal reaction is completed, the obtained product is post-treated. The post-treatment is specifically as follows: the product is washed three times with a washing solution, centrifuged at a speed of 3000 rpm for 5 minutes after each washing, the supernatant is discarded, and finally dried at 60-100°C.
[0019] On the one hand, the present invention provides an iron-cobalt bimetallic hydroxide oxide obtained by the preparation method.
[0020] On the other hand, the present invention proposes an application of the iron-cobalt bimetallic hydroxide catalyst, including: using the iron-cobalt bimetallic hydroxide catalyst as the anode to produce hydrogen by urea-assisted electrolysis of water in an alkaline solution.
[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0022] 1. The preparation process of the method of the present invention is simple, convenient, efficient, has mild reaction conditions, has extremely high repeatability, and is suitable for industrial production and application.
[0023] 2. The iron-cobalt bimetallic hydroxide catalyst prepared by the present invention has a needle-like nanostructure, strong tip effect. When a voltage is applied, the electric field strength will be amplified at the tip, thereby enhancing the urea oxidation efficiency. And the needle-like structure is conducive to the diffusion of electrolytes and products, promoting the mass transfer process.
[0024] 3. The iron-cobalt bimetallic hydroxide catalyst prepared by the present invention has more catalytic active sites and excellent stability.
[0025] 4. The present invention improves the performance of the anode for urea-assisted alkaline electrolysis of water by cobalt-iron co-assembly, and significantly improves the catalytic activity of urea decomposition on the premise of not using precious metals and reducing the catalyst cost.
[0026] 5. The preparation of the iron-cobalt bimetallic hydroxide catalyst of the present invention can be carried out in large quantities, does not require expensive equipment, and can be widely used in urea-assisted water electrolysis hydrogen production devices. Description of the Drawings
[0027] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. And throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:
[0028] Figure 1 is the Scanning electron microscopy (SEM) image of the iron-cobalt bimetallic hydroxide catalyst prepared in Example 2;
[0029] Figure 2 is the High-resolution transmission electron microscopy (HRTEM) image of the iron-cobalt bimetallic hydroxide catalyst prepared in Example 2 of the present invention;
[0030] Figure 3XRD pattern of the iron-cobalt bimetallic hydroxide catalyst prepared in Example 2 of the present invention;
[0031] Figure 4 Performance comparison chart of the urea oxidation reaction of the iron-cobalt bimetallic hydroxide catalyst prepared in Example 2 of the present invention, FeOOH prepared in Comparative Example 1, and Co(OH)2 prepared in Comparative Example 2;
[0032] Figure 5 Stability comparison chart of the urea oxidation reaction of the iron-cobalt bimetallic hydroxide catalyst prepared in Example 2 of the present invention;
[0033] Figure 6 Performance comparison chart of the catalytic performance of the urea-assisted alkaline anion electrolyzer in which the iron-cobalt bimetallic hydroxide catalyst prepared in Example 2 of the present invention, FeOOH prepared in Comparative Example 1, and Co(OH)2 prepared in Comparative Example 2 are respectively combined with the commercial noble metal Pt / C / NF prepared in Comparative Example 3;
[0034] Figure 7 Stability comparison chart of the catalytic stability of the urea-assisted alkaline anion electrolyzer in which the iron-cobalt bimetallic hydroxide catalyst prepared in Example 2 of the present invention, FeOOH prepared in Comparative Example 1, and Co(OH)2 prepared in Comparative Example 2 are respectively combined with the commercial noble metal Pt / C / NF prepared in Comparative Example 3;
[0035] Figure 8 Flow chart of the preparation method of the iron-cobalt bimetallic hydroxide catalyst provided in the embodiment of the present invention. Detailed implementation manners
[0036] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. Hereinafter, the present invention will be described in detail with reference to the drawings and in combination with the embodiments.
[0037] The efficient realization of urea oxidation coupled hydrogen production is highly dependent on high-performance catalysts, and requires precise control of the catalyst electronic structure to improve the stability and activity of the reaction. At present, there are many limitations in the catalysts used in this field. Although precious metal-based catalysts (such as ruthenium, palladium, etc.) show excellent catalytic activity, their rarity and high cost greatly limit the feasibility of large-scale industrial applications; in contrast, non-precious metal catalysts often perform poorly in key performance indicators such as catalytic activity, long-term stability, and selectivity for urea oxidation reactions, resulting in low conversion efficiency, limited hydrogen yield, and easy to cause side reaction interference, which seriously hinders the further development of urea oxidation coupled hydrogen production technology.
[0038] Therefore, it is necessary to design an iron-cobalt bimetallic hydroxide catalyst to solve the problems that the existing catalyst is not suitable for industrial production, has poor stability, low catalytic activity and low oxidation efficiency.
[0039] On the one hand, in some embodiments of the present invention, the preparation method of the iron-cobalt bimetallic oxyhydroxide catalyst comprises the following steps:
[0040] Pre-treating the nickel foam and setting it aside to obtain the nickel foam for use;
[0041] Dissolving ferric nitrate nonahydrate and cobalt nitrate hexahydrate in water, and performing a first stirring until they are completely dissolved, to obtain a first mixed solution;
[0042] adding ammonium fluoride to the first mixed solution, performing a second stirring until it is completely dissolved, and then adding urea and performing a third stirring to obtain a second mixed solution;
[0043] The second mixed solution is mixed with the nickel foam to be used, and a hydrothermal reaction is performed to obtain iron-cobalt bimetallic oxyhydroxide (Co-FeOOH).
[0044] It can be understood that the preparation process is simple and convenient, highly efficient, mild in reaction conditions, and reproducible, and is extremely suitable for large-scale industrial production.
[0045] In some embodiments of the present invention, the pretreatment is specifically as follows: the nickel foam is first soaked in 3 mol / L hydrochloric acid for 15 minutes and then washed with water, and then the nickel foam is ultrasonically treated in anhydrous ethanol and water for 5 minutes respectively, and then washed with water three times and then taken out and dried naturally.
[0046] Specifically, the water is preferably ultrapure water.
[0047] It is understandable that during the storage and processing of nickel foam, an oxide layer is likely to form on its surface. These oxide layers will hinder the subsequent deposition and reaction of active substances on the surface of nickel foam. By soaking in HCl and then ultrasonically impregnating in ultrapure water and absolute ethanol, the surface oxide layer can be effectively removed, exposing more active sites on the surface of nickel foam.
[0048] In some embodiments of the present invention, the rotation speeds of the first stirring, the second stirring, and the third stirring are: 400 - 600 rpm; the time of the third stirring is 5 - 10 minutes; the rotation speed of the stirring is preferably 500 rpm, and the time of the third stirring is preferably 8 minutes.
[0049] Specifically, when performing the second stirring, ammonium fluoride is slowly added and then stirred while adding to prevent precipitation due to excessive local concentration.
[0050] In some embodiments of the present invention, the molar concentration of iron(III) nitrate nonahydrate is 1 - 2 mM; the molar concentration of cobalt(II) nitrate hexahydrate is 0.3 - 1 mM; the molar concentration of urea is 1 - 10 mM; the molar concentration of ammonium fluoride is 1 - 3 mM; the molar concentration of iron(III) nitrate nonahydrate is preferably 1.5 mM, the molar concentration of cobalt(II) nitrate hexahydrate is preferably 0.5 mM, the molar concentration of urea is preferably 5 mM, and the molar concentration of ammonium fluoride is preferably 2 mM.
[0051] In some embodiments of the present invention, the temperature for dissolving iron(III) nitrate nonahydrate and cobalt(II) nitrate hexahydrate is 40 - 50 °C; the dissolving temperature is preferably 45 °C.
[0052] It is understandable that heating water helps to increase the dissolution rate of raw materials such as iron nitrate and cobalt nitrate.
[0053] In some embodiments of the present invention, the hydrothermal reaction specifically involves heating to 100 - 120 °C at a first heating rate and maintaining for 2 - 3 hours, and then heating to 140 - 160 °C at a second heating rate and maintaining for 6 - 9 hours. The first heating temperature is preferably 120 °C, and the maintaining time is preferably 2.5 hours; the second heating temperature is preferably 140 °C, and the maintaining time is preferably 8 hours.
[0054] It is understandable that the method of segmented heating can better control the crystal growth process, which is beneficial to the formation of an iron - cobalt bimetallic hydroxide oxide catalyst with high crystallinity and uniform particle size.
[0055] In some embodiments of the present invention, the first heating rate is: 10 - 15 °C / min; the second heating rate is: 3 - 5 °C / min. The first heating rate is preferably 13 °C / min, and the second heating rate is preferably 4 °C / min.
[0056] It can be understood that heating at a faster heating rate in the early stage of the reaction can allow the raw materials to react initially and form nuclei, and subsequently heating at a lower heating rate is conducive to the formation of an iron-cobalt bimetallic hydroxide catalyst with high crystallinity and uniform particle size.
[0057] In some embodiments of the present invention, after the hydrothermal reaction is completed, the obtained product is post-treated, and the post-treatment is specifically: the product is washed three times with a washing solution, centrifuged at a speed of 3000 rpm for 5 minutes after each washing, the supernatant is discarded, and finally dried at 60-100°C; the drying temperature is preferably 80°C.
[0058] Specifically, the preparation method of the washing liquid is: mixing ultrapure water and anhydrous ethanol in a volume ratio of 9:1; the drying is vacuum drying with a vacuum degree of 0.09 MPa.
[0059] It is understandable that ethanol can reduce the surface tension of the product, help remove impurities, and accelerate the subsequent drying process. Vacuum drying can reduce the boiling point of water, speed up the drying speed, and effectively prevent the product from being oxidized during the drying process, thereby improving the purity and performance of the product.
[0060] On the one hand, in some embodiments of the present invention, an iron-cobalt bimetallic oxyhydroxide is also provided.
[0061] On the other hand, in some embodiments of the present invention, an application of the iron-cobalt bimetallic oxyhydroxide catalyst is provided, specifically, the iron-cobalt bimetallic oxyhydroxide catalyst is used as an anode to produce hydrogen through urea-assisted water electrolysis in an alkaline solution.
[0062] Example 1
[0063] S1, soaking the nickel foam in 3 mol / L hydrochloric acid for 15 min and then washing with ultrapure water, then ultrasonically treating the nickel foam in anhydrous ethanol and ultrapure water for 5 min respectively, then washing with ultrapure water three times and then taking out and drying naturally to obtain a nickel foam for use;
[0064] S2, dissolving 1 mM ferric nitrate nonahydrate and 0.3 mM cobalt nitrate hexahydrate in water at a temperature of 40° C., and stirring at a speed of 400 rpm until completely dissolved to obtain a first mixed solution;
[0065] S3, slowly adding 1 mM ammonium fluoride to the first mixed solution, stirring at a speed of 400 rpm, until it is completely dissolved, then adding 1 mM urea and stirring at a speed of 400 rpm for 5 minutes to obtain a second mixed solution;
[0066] S4, mixing the second mixed solution with the nickel foam to be used, raising the temperature to 100° C. at a heating rate of 10° C. / min, maintaining for 2 hours, and then raising the temperature to 140° C. at a heating rate of 3° C. / min, maintaining for 6 hours;
[0067] S5. After completion, the obtained product is washed three times with a washing solution, centrifuged at a speed of 3000 rpm for 5 minutes after each washing, the supernatant is discarded, and finally dried at 60° C. to obtain the iron-cobalt bimetallic hydroxide catalyst.
[0068] Example 2
[0069] S1, soaking the nickel foam in 3 mol / L hydrochloric acid for 15 min and then washing with ultrapure water, then ultrasonically treating the nickel foam in anhydrous ethanol and ultrapure water for 5 min respectively, then washing with ultrapure water three times and then taking out and drying naturally to obtain a nickel foam for use;
[0070] S2, dissolving 1.5 mM ferric nitrate nonahydrate and 0.5 mM cobalt nitrate hexahydrate in water at a temperature of 45° C., and stirring at a speed of 500 rpm until completely dissolved to obtain a first mixed solution;
[0071] S3, slowly adding 2 mM ammonium fluoride to the first mixed solution, stirring at a speed of 500 rpm, until completely dissolved, then adding 5 mM urea and stirring at a speed of 500 rpm for 8 minutes to obtain a second mixed solution;
[0072] S4, mixing the second mixed solution with the stand-by nickel foam, raising the temperature to 120° C. at a heating rate of 13° C. / min, maintaining for 2.5 hours, and then raising the temperature to 140° C. at a heating rate of 4° C. / min, maintaining for 8 hours;
[0073] S5. After completion, the obtained product is washed three times with a washing solution, centrifuged at a speed of 3000 rpm for 5 minutes after each washing, the supernatant is discarded, and finally dried at 80° C. to obtain the iron-cobalt bimetallic hydroxide catalyst.
[0074] Example 3
[0075] S1, soaking the nickel foam in 3 mol / L hydrochloric acid for 15 min and then washing with ultrapure water, then ultrasonically treating the nickel foam in anhydrous ethanol and ultrapure water for 5 min respectively, then washing with ultrapure water three times and then taking out and drying naturally to obtain a nickel foam for use;
[0076] S2, dissolving 2 mM ferric nitrate nonahydrate and 1 mM cobalt nitrate hexahydrate in water at a temperature of 50° C., and stirring at a speed of 600 rpm until completely dissolved to obtain a first mixed solution;
[0077] S3, slowly adding 2 mM ammonium fluoride to the first mixed solution, stirring at a speed of 600 rpm, until completely dissolved, then adding 10 mM urea and stirring at a speed of 600 rpm for 10 minutes to obtain a second mixed solution;
[0078] S4, mixing the second mixed solution with the nickel foam to be used, raising the temperature to 120° C. at a heating rate of 15° C. / min, maintaining for 3 hours, and then raising the temperature to 160° C. at a heating rate of 5° C. / min, maintaining for 9 hours;
[0079] S5. After completion, the obtained product is washed three times with a washing solution, centrifuged at a speed of 3000 rpm for 5 minutes after each washing, the supernatant is discarded, and finally dried at 100° C. to obtain the iron-cobalt bimetallic hydroxide catalyst.
[0080] Comparative Example 1
[0081] S1, soaking the nickel foam in 3 mol / L hydrochloric acid for 15 min and then washing with ultrapure water, then ultrasonically treating the nickel foam in anhydrous ethanol and ultrapure water for 5 min respectively, then washing with ultrapure water three times and then taking out and drying naturally to obtain a nickel foam for use;
[0082] S2, dissolving 1.5 mM ferric nitrate nonahydrate in water at a temperature of 45° C., and stirring at a speed of 500 rpm until completely dissolved to obtain a first mixed solution;
[0083] S3, slowly adding 2 mM ammonium fluoride to the first mixed solution, stirring at a speed of 500 rpm, until completely dissolved, then adding 5 mM urea and stirring at a speed of 500 rpm for 8 minutes to obtain a second mixed solution;
[0084] S4, mixing the second mixed solution with the stand-by nickel foam, raising the temperature to 120° C. at a heating rate of 13° C. / min, maintaining for 2.5 hours, and then raising the temperature to 140° C. at a heating rate of 4° C. / min, maintaining for 8 hours;
[0085] S5. After completion, the obtained product is washed three times with a washing solution, centrifuged at a speed of 3000 rpm for 5 minutes after each washing, the supernatant is discarded, and finally dried at 80° C. to obtain FeOOH.
[0086] Comparative Example 2
[0087] S1, soaking the nickel foam in 3 mol / L hydrochloric acid for 15 min and then washing with ultrapure water, then ultrasonically treating the nickel foam in anhydrous ethanol and ultrapure water for 5 min respectively, then washing with ultrapure water three times and then taking out and drying naturally to obtain a nickel foam for use;
[0088] S2, dissolving 0.5 mM cobalt nitrate hexahydrate in water at a temperature of 45° C., and stirring at a speed of 500 rpm until completely dissolved to obtain a first mixed solution;
[0089] S3, slowly adding 2 mM ammonium fluoride to the first mixed solution, stirring at a speed of 500 rpm, until it is completely dissolved, then adding 5 mM urea and stirring at a speed of 500 rpm for 8 minutes to obtain a second mixed solution;
[0090] S4, mixing the second mixed solution with the nickel foam to be used, raising the temperature to 120° C. at a heating rate of 13° C. / min, maintaining for 2.5 hours, and then raising the temperature to 140° C. at a heating rate of 4° C. / min, maintaining for 8 hours;
[0091] S5. After completion, the obtained product was washed three times with a washing solution, centrifuged at 3000 rpm for 5 minutes after each washing, the supernatant was discarded, and finally dried at 80°C to obtain Co(OH) 2 .
[0092] Comparative Example 3
[0093] The existing Pt / C catalyst was coated on nickel foam after ultrasonic dispersion in ethanol. The loading of a single nickel foam carrier was 1 mg / cm2 to obtain a commercial Pt / C / NF catalyst.
[0094] Effect test
[0095] Test 1
[0096] The Co-FeOOH material prepared in Example 2 of the present invention was subjected to SEM, TEM and XRD tests. The results are as follows Figure 1-3 As shown: Figure 1 The needle-shaped Co-FeOOH catalyst can be seen. The tip effect of the needle-shaped catalyst will enhance the local electric field strength and improve electron transfer. The nano-needle-shaped structure will expose more active sites, thereby improving the catalytic performance. Figure 2 Clear lattice fringes can be clearly seen, and the lattice spacings of 0.741 and 0.254 nm represent the (110) and (211) crystal planes of Co-FeOOH, respectively; Figure 3 It shows that the Co-FeOOH material prepared in the example has the diffraction peak of FeOOH.
[0097] Test 2
[0098] The Co-FeOOH prepared in Example 2, the FeOOH prepared in Comparative Example 1 and the Co(OH) prepared in Comparative Example 2 were 2 Conduct UOR performance testing:
[0099] The electrolytic cell was selected as the container, the test sample was the working electrode, the platinum wire was the auxiliary electrode, the Ag / AgCl electrode was the reference electrode, and the electrolyte was 1M KOH + 0.33M urea solution. The test was carried out using an electrochemical workstation. All voltage ranges mentioned in this article are relative to the reversible hydrogen electrode (RHE).
[0100] UOR performance test conditions: Temperature: room temperature; LSV scan rate: 10 mV / s; LSV test voltage range: 0 - 2.5 V.
[0101] UOR stability test conditions: Temperature: room temperature; Current density: 100 mA / cm2; Test time: 60 h.
[0102] The test results are as Figure 4-5 shown. Specifically, it can be seen from the figure that the Co-FeOOH catalyst has excellent UOR catalytic performance and stability. The voltage of the catalyst is 1.59 V at a current density of 1000 mA / cm2, which is significantly better than that of FeOOH and Co(OH) 2 , and the performance of the catalyst changes little after 60 h of urea oxidation reaction at a current density of 100 mA / cm2.
[0103] Test 3
[0104] Co-FeOOH, FeOOH, Co(OH) prepared in Example 2 2 and commercial Pt / C / NF catalysts were used as the cathode and anode respectively to assemble a urea-assisted alkaline anion electrolytic cell for performance and stability tests. The electrolytic cell was selected as the container, the test sample was the working electrode, and the electrolyte was 1M KOH + 0.33M urea solution.
[0105] Performance test conditions: Temperature: room temperature; LSV scan rate: 10 mV / s; LSV test voltage range: 0 - 5 V.
[0106] Stability test conditions: Temperature: room temperature; Current density: 1000 mA / cm2; Test time: 24 h.
[0107] The test results are as Figure 6-7 shown. Specifically, it can be seen from the figure that the urea-assisted alkaline anion electrolytic cell assembled with the Pt / C / NF catalyst and the Co-FeOOH catalyst has better performance than the urea-assisted alkaline anion electrolytic cells assembled with FeOOH and Co(OH)2 respectively. The electrolysis voltage is 2.8 V at a current density of 1000 mA / cm2, and it has very good stability. The performance of the catalyst changes little after 24 h of electrolysis at a current density of 1000 mA / cm2.
[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or make equivalent replacements, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the protection scope of the claims of the present invention.
Claims
1. A method for preparing an iron-cobalt bimetallic oxyhydroxide catalyst, characterized in that: The following steps are involved: Pre-treating the nickel foam and setting it aside to obtain the nickel foam for use; Dissolving ferric nitrate nonahydrate and cobalt nitrate hexahydrate in water, and performing a first stirring until they are completely dissolved, to obtain a first mixed solution; adding ammonium fluoride to the first mixed solution, performing a second stirring until it is completely dissolved, and then adding urea and performing a third stirring to obtain a second mixed solution; The second mixed solution is mixed with the nickel foam to be used, and a hydrothermal reaction is carried out to obtain an iron-cobalt bimetallic oxyhydroxide.
2. The method for preparing an iron-cobalt bimetallic oxyhydroxide catalyst according to claim 1, characterized in that: The pretreatment is specifically as follows: the nickel foam is first immersed in 3 mol / L hydrochloric acid for 15 minutes and then washed with water, and then the nickel foam is ultrasonically treated in anhydrous ethanol and water for 5 minutes respectively, and then washed with water three times and then taken out for natural drying.
3. The method for preparing an iron-cobalt bimetallic oxyhydroxide catalyst according to claim 1, characterized in that: The first stirring, the second stirring and the third stirring speed are 400-600 rpm; the third stirring time is 5-10 minutes.
4. The method for preparing an iron-cobalt bimetallic oxyhydroxide catalyst according to claim 1, characterized in that: The molar concentration of the ferric nitrate nonahydrate is 1-2 mM; the molar concentration of the cobalt nitrate hexahydrate is 0.3-1 mM; the molar concentration of urea is 1-10 mM; and the molar concentration of ammonium fluoride is 1-3 mM.
5. The method for preparing an iron-cobalt bimetallic oxyhydroxide catalyst according to claim 1, characterized in that: The temperature at which the ferric nitrate nonahydrate and the cobalt nitrate hexahydrate are dissolved is 40-50°C.
6. The method for preparing an iron-cobalt bimetallic oxyhydroxide catalyst according to claim 1, characterized in that: The hydrothermal reaction is specifically as follows: heating to 100-120° C. at a first heating rate, maintaining for 2-3 hours, and then heating to 140-160° C. at a second heating rate, maintaining for 6-9 hours.
7. The method for preparing an iron-cobalt bimetallic oxyhydroxide catalyst according to claim 6, characterized in that: The first heating rate is 10-15°C / min; the second heating rate is 3-5°C / min.
8. The method for preparing an iron-cobalt bimetallic oxyhydroxide catalyst according to claim 1, characterized in that: After the hydrothermal reaction is completed, the obtained product is post-treated. The post-treatment is specifically as follows: the product is washed three times with a washing solution, centrifuged at a speed of 3000 rpm for 5 minutes after each washing, the supernatant is discarded, and finally dried at 60-100°C.
9. An iron-cobalt bimetallic oxyhydroxide catalyst obtained by the preparation method according to any one of claims 1 to 8.
10. Use of the iron-cobalt bimetallic oxyhydroxide catalyst according to any one of claims 1 to 8, characterized in that: The iron-cobalt bimetallic oxyhydroxide catalyst is used as an anode to produce hydrogen through urea-assisted water electrolysis in an alkaline solution.