A method for preparing bromine-doped two-dimensional nickel-iron oxide and its application

Abstract

This invention provides a method for preparing bromine-doped two-dimensional nickel-iron oxide and its application, belonging to the field of nanomaterial preparation technology. This invention involves reacting succinic acid, ethylene glycol, metal salt, and bromide salt in a mixed solution, combined with Joule heating rapid heating and cooling technology, to form a bromide-doped two-dimensional porous structure. This method has a simple synthesis process, and the prepared catalyst exhibits low overpotential and excellent stability in alkaline seawater electrolysis, significantly improving OER reaction efficiency and providing a highly efficient and durable electrochemical catalyst for seawater hydrogen production technology.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation technology, specifically relating to a method for preparing bromine-doped two-dimensional nickel-iron oxide and its application in seawater electrolysis. Background Technology

[0002] Seawater electrolysis for hydrogen production is a clean energy technology that is of great significance for reducing carbon emissions and promoting a sustainable energy transition. In this process, the anode catalyst plays a crucial role. Specifically, the anode catalyst can effectively reduce the overpotential of the oxygen evolution reaction, thereby improving electrolysis efficiency. Therefore, developing efficient, stable, and durable anode catalysts is key to advancing seawater electrolysis for hydrogen production technology.

[0003] Among numerous anode catalyst materials, nickel-iron oxides have emerged as a potentially ideal choice due to their tunable electronic structure and relatively low cost. However, nickel-iron oxides still face some challenges, such as relatively low catalytic activity and susceptibility to chloride ions (Cl-) in seawater. - ) and hypochlorite (ClO) - Corrosion and other issues limit its performance in practical applications.

[0004] To overcome these limitations, researchers proposed processing nickel-iron oxide into a two-dimensional porous structure. Two-dimensional materials possess a large specific surface area, high porosity, and good mass diffusion efficiency, providing more active sites. Simultaneously, the large specific surface area and porosity make two-dimensional materials easier to modify with heteroatoms, thereby forming a passivation layer on their surface to protect the anodic active sites from Cl. - / ClO -Corrosion. Common synthesis methods, such as vapor deposition and wet chemical methods, still have certain limitations. Although vapor deposition can precisely control the thickness and morphology of materials, its equipment is expensive and the operation is complex, limiting its large-scale application. For example, Chinese patent document CN117448793A discloses a thin-layer two-dimensional oxide material and its preparation and application. This patent first treats the substrate with gas plasma, and then chemically vapor-deposits oxides on the substrate, thereby growing thin-layer two-dimensional oxide materials. This preparation process requires high-end equipment and has high preparation costs, making it unsuitable for large-scale production. Compared with vapor deposition, wet chemical methods are favored due to their lower cost, simplicity, and efficiency. They are relatively easy to use for the large-scale preparation of nanosheets of layered materials such as layered double hydroxides (LDHs), but the preparation of nanosheets of non-layered metal oxides still faces significant challenges. Most methods rely on templates to facilitate the formation of two-dimensional structures. For example, Chinese patent document CN107253701A discloses a method for preparing ultrathin two-dimensional nanomaterials. This patent first disperses metal salts and graphene oxide in a pre-prepared buffer solution with a target pH, then reacts them in a liquid phase under heating. After washing and drying, the prepared powder is calcined in a muffle furnace to obtain two-dimensional metal oxides. This process is cumbersome, requires the preparation of buffer solutions and uses graphene oxide as a sacrificial template, resulting in high costs and low efficiency in the preparation of two-dimensional metal oxides, making it unsuitable for industrialization. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing bromine-doped two-dimensional nickel-iron metal oxides. This method has a simple synthesis process, and the prepared catalyst achieves excellent stability with low overpotential in alkaline seawater electrolysis, significantly improving the OER reaction efficiency and providing a highly efficient and durable electrochemical catalyst for seawater hydrogen production technology.

[0006] To achieve this objective, the technical solution of the present invention is as follows:

[0007] A method for preparing a bromine-doped two-dimensional nickel-iron oxide includes the following steps:

[0008] (1) Succinic acid, ethylene glycol, ferric nitrate nonahydrate, nickel nitrate hexahydrate, and bromide salt are dissolved in a mixed solution of water and methanol, and stirred under heating until the liquid is completely evaporated to obtain the first solid.

[0009] (2) The first solid was placed in a Joule-heated graphite groove and subjected to Joule heat treatment in an air atmosphere. After cooling to room temperature, the resulting solid was washed with deionized water and dried to obtain bromine-doped two-dimensional nickel-iron oxide.

[0010] Further, in step (1), the mass ratio of succinic acid, ethylene glycol, ferric nitrate nonahydrate, nickel nitrate hexahydrate, and bromide is 1:0.1~0.2:0.3~0.9:0.3~0.9:5~10.

[0011] Furthermore, in step (1), the bromide salt is sodium bromide or potassium bromide.

[0012] Furthermore, in step (1), the ratio of the volume of the mixed solution of succinic acid, water and methanol used is 1 mg: 0.5~1 mL; the volume ratio of water and methanol used is 1: 0.3~0.5.

[0013] Furthermore, in step (1), the heating temperature is 130~160℃.

[0014] Further, in step (2), the Joule thermal shock temperature is 850~1200℃, the heating rate is 1000-2500℃ / s, and the number of Joule thermal shocks is 2~5 times; the Joule thermal shock is the process of heating from room temperature to the target temperature and then naturally cooling back to room temperature, which is represented as one time.

[0015] Another object of the present invention is to provide an application of a bromine-doped two-dimensional nickel-iron oxide prepared by the above method, using the two-dimensional nickel-iron oxide as an electrochemical catalyst for the OER reaction in alkaline seawater electrolyte.

[0016] Compared with the prior art, the beneficial effects of this invention are as follows:

[0017] 1. This invention utilizes a wet chemical method combined with Joule heating rapid heating and cooling technology to produce a gas template through the esterification reaction of succinic acid and ethylene glycol, thereby completing the molding and bromine doping of a two-dimensional porous structure in one step. This method does not require a template or a high vacuum environment, the raw materials are readily available, the equipment requirements are low, and the preparation efficiency is significantly improved.

[0018] 2. In this invention, succinic acid adsorbs metal ions and reacts with ethylene glycol to form a metal-ester mixture. Then, nitrate ions are oxidized at high temperature and pyrolyzed at high temperature to form a large amount of gas. A large number of bubbles are blown into the liquefied metal-ester mixture and used as templates to promote the formation of two-dimensional porous nickel-iron metal oxide.

[0019] 3. This invention utilizes the synergistic effect of bromide salts and Joule heating to effectively dope bromide ions into two-dimensional porous nickel-iron metal oxides. During Joule thermal shock, the high temperature induces bromide ions to replace oxygen ions in the nickel-iron metal oxide, while the rapid cooling function of Joule heating during the cooling phase prevents complete oxidation of the bromide-doped two-dimensional nickel-iron oxide and also inhibits sintering of the bromide-doped two-dimensional porous nickel-iron oxide.

[0020] 4. Compared with traditional methods for preparing two-dimensional metal oxides, this invention offers higher catalytic efficiency, lower energy consumption, and a simpler process. Furthermore, the doping of bromide ions significantly enhances the corrosion resistance of nickel-iron oxides, thereby improving the efficiency of its seawater electrocatalytic oxygen evolution reaction (OER). At 10 mA cm⁻¹ -2 At the given current density, the catalyst-modified glassy carbon electrode in the examples required a minimum overpotential of only 210.4 mV, significantly lower than that of commercial RuO2 (351.4 mV @ 10 mA cm⁻¹). -2 ), and at 10mA cm -2 After being tested at a current density for 100 hours, the overpotential hardly increased, and no chlorine evolution reaction occurred, demonstrating excellent electrocatalytic performance and making it easy to industrialize. Attached Figure Description

[0021] Figure 1 The scanning electron microscope (SEM) image and elemental distribution (EDS mapping) image of the bromine-doped two-dimensional nickel-iron oxide prepared in Example 1 are shown below.

[0022] Figure 2 The results of nitrogen adsorption-desorption (N2-BET) test of the bromine-doped two-dimensional nickel-iron oxide prepared in Example 1 are shown below.

[0023] Figure 3 Linear sweep voltammetry (LSV) curves of the modified electrode using the bromine-doped two-dimensional nickel-iron oxide prepared in Example 1 as a catalyst;

[0024] Figure 4 Using the bromine-doped two-dimensional nickel-iron oxide prepared in Example 1 as a catalyst, the modified electrode was tested at 10 mAcm. -2 Timing potential diagram under current density;

[0025] Figure 5 SEM image of the bromine-doped nickel-iron oxide prepared in Comparative Example 1;

[0026] Figure 6 The image shows a SEM image of the bromine-doped nickel-iron oxide prepared in Comparative Example 2. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention, but the scope of protection of the present invention is not limited thereto.

[0028] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available materials; unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art.

[0029] In various embodiments of the specific implementation of the present invention, the Joule heating rapid heating device used consists of a gas path device, a vacuum pump, a graphite sample stage, a temperature control system, and a data acquisition system. The device is model CIS-JH3.3-P, with an output voltage of 0-40V, an output current of 0-500A, a temperature measurement range of 0-3000°C, a power supply of 380V / 30A, and a current ramp-up time of 1ms.

[0030] Example 1

[0031] (1) Dissolve 100 mg succinic acid, 15 mg ethylene glycol, 45 mg ferric nitrate nonahydrate, 45 mg nickel nitrate hexahydrate, and 800 mg potassium bromide in a mixed solution of 70 mL water and methanol. Stir at 150 °C until the liquid is completely evaporated to obtain the first solid. The ratio of water to methanol used is 1:0.4.

[0032] (2) 100 mg of the first solid was transferred to a quartz boat (15 mL) fixed in the groove of the graphite heating plate and subjected to Joule thermal shock three times in air atmosphere. The Joule thermal shock temperature was 1000 °C and the heating rate was 1500 °C / s. After cooling to room temperature, the obtained solid was washed with deionized water and dried to obtain bromine-doped two-dimensional nickel-iron oxide, which is recorded as Example 1.

[0033] The Example 1 obtained in step (2) was subjected to SEM testing, EDS Mapping testing, and N2-BET testing. The test results are shown in the figure below. Figure 1 and Figure 2 The pore size distribution test results of N2-BET are the total pore size distribution modeled by NLDFT.

[0034] Depend on Figure 1 It can be seen that the bromine-doped two-dimensional nickel-iron oxide prepared in Example 1 has a plate-like structure, in which bromine, iron, and nickel are uniformly distributed, indicating the successful preparation of the bromine-doped two-dimensional nickel-iron oxide.

[0035] Depend on Figure 2 It can be seen that the bromine-doped two-dimensional nickel-iron oxide prepared in Example 1 is a porous material with a main pore size distribution range of 3-60 nm. It belongs to a hierarchical porous structure of mesoporous and macroporous structures, with a specific surface area of ​​63.4 m². 2 / g, its porous structure not only facilitates the exposure of active sites, but also facilitates the desorption of oxygen from the product, thus improving the OER performance in alkaline seawater electrolysis.

[0036] The bromine-doped two-dimensional nickel-iron oxide catalyst obtained in step (2) is used in seawater electrocatalytic oxygen evolution (OER) applications, including the following application steps:

[0037] 4 mg of bromine-doped two-dimensional nickel-iron oxide catalyst and 1 mg of commercial carbon black were dispersed in 0.5 mL of an ethanol-Nafion mixed solution (0.48 mL of ethanol and 0.02 mL of 0.5% Nafion solution). After sonication for 2 h, a uniformly dispersed bromine-doped two-dimensional nickel-iron oxide catalyst mixed solution was obtained. 10 μL of the bromine-doped two-dimensional nickel-iron oxide catalyst mixed solution was dropped onto a glassy carbon electrode and air-dried to obtain a glassy carbon electrode modified with bromine-doped two-dimensional nickel-iron oxide catalyst. Electrochemical tests were performed on a CHI760E electrochemical workstation. The glassy carbon electrode modified with bromine-doped two-dimensional nickel-iron oxide catalyst was used as the working electrode, a graphite rod as the counter electrode, saturated mercury / mercuric oxide as the reference electrode, and 1 M KOH seawater solution as the electrolyte. Linear sweep voltammetry (LSV) and stability tests of the oxygen evolution reaction were performed. The test results are shown in the table below. Figure 3 , Figure 4 The seawater used was taken from the Bohai Sea.

[0038] Depend on Figure 3 It can be seen that at 10mA cm -2 At the specified current density, the glassy carbon electrode modified with the catalyst in Example 1 requires only 210.4 mV overpotential, which is significantly lower than that of commercial RuO2 (351.4 mV @ 10 mA cm⁻¹). -2 It has broad prospects for industrial application.

[0039] Depend on Figure 4 It can be seen that at 10mA cm -2 After testing at a current density for 100 hours, the overpotential hardly increased, and no hypochlorite ions were detected in the electrolyte by ion chromatography. This indicates that the glassy carbon electrode modified with the catalyst in Example 1 mainly undergoes the OER reaction and does not undergo the chlorine evolution reaction, while also exhibiting excellent stability.

[0040] Example 2

[0041] (1) Dissolve 100 mg succinic acid, 10 mg ethylene glycol, 30 mg ferric nitrate nonahydrate, 90 mg nickel nitrate hexahydrate, and 500 mg potassium bromide in a 50 mL mixture of water and methanol. Stir at 130 °C until the liquid is completely evaporated to obtain the first solid. The ratio of water to methanol used is 1:0.3.

[0042] (2) 100 mg of the first solid was transferred to a quartz boat (15 mL) fixed in the groove of the graphite heating plate and subjected to Joule thermal shock 5 times in air atmosphere. The Joule thermal shock temperature was 850 °C and the heating rate was 1000 °C / s. After cooling to room temperature, the obtained solid was washed and dried with deionized water to obtain bromine-doped two-dimensional nickel-iron oxide, which is recorded as Example 2.

[0043] The bromine-doped two-dimensional nickel-iron oxide catalyst obtained in step (2) was subjected to elemental composition (EDS) testing and N2-BET testing and applied to seawater electrocatalytic oxygen evolution (OER) application. The testing steps and methods were the same as in Example 1, and the test results are shown in Table 1.

[0044] As shown in Table 1, the elemental composition of Example 2 is similar to that of Example 1, consisting of Ni, Fe, O, and Br. In addition, Example 2 also has a porous structure with a specific surface area of ​​72.7 m². 2 / g, at 10mA cm -2 At the specified current density, the glassy carbon electrode modified with the catalyst in Example 2 requires only 223.7 mV overpotential, which is significantly lower than that of commercial RuO2 (351.4 mV @ 10 mA cm⁻¹). -2 It has broad prospects for industrial application.

[0045] Example 3

[0046] (1) Dissolve 100 mg succinic acid, 20 mg ethylene glycol, 90 mg ferric nitrate nonahydrate, 30 mg nickel nitrate hexahydrate, and 1000 mg sodium bromide in a mixed solution of 100 mL water and methanol. Stir at 160 °C until the liquid is completely evaporated to obtain the first solid. The ratio of water to methanol used is 1:0.5.

[0047] (2) 100 mg of the first solid was transferred to a quartz boat (15 mL) fixed in the groove of the graphite heating plate and subjected to Joule thermal shock twice in air atmosphere. The Joule thermal shock temperature was 1200 °C and the heating rate was 2500 °C / s. After cooling to room temperature, the obtained solid was washed and dried with deionized water to obtain bromine-doped two-dimensional nickel-iron oxide, which is recorded as Example 3.

[0048] The bromine-doped two-dimensional nickel-iron oxide catalyst obtained in step (2) was subjected to EDS and N2-BET tests and used in seawater electrocatalytic oxygen evolution (OER) application. The test steps and methods were the same as in Example 1, and the test results are shown in Table 1.

[0049] As shown in Table 1, the elemental composition of Example 3 is similar to that of Example 1, consisting of Ni, Fe, O, and Br. In addition, Example 3 also has a porous structure with a specific surface area of ​​55.3 m². 2 / g, at 10mA cm -2 At the specified current density, the glassy carbon electrode modified with the catalyst in Example 2 requires only 242.6 mV overpotential, which is significantly lower than that of commercial RuO2 (351.4 mV @ 10 mA cm⁻¹). -2 It has broad prospects for industrial application.

[0050] Comparative Example 1

[0051] The difference between Comparative Example 1 and Example 1 is that in step (1), the amount of succinic acid used is 0 mg, and the rest of the methods are the same as in Example 1.

[0052] The comparative example 1 obtained in step (2) was subjected to SEM testing, EDS testing, N2-BET testing, and seawater electrocatalytic oxygen evolution (OER) application. The testing steps and methods were the same as in example 1. The test results are shown in […]. Figure 5 See Table 1.

[0053] Depend on Figure 5 It can be seen that Comparative Example 1 is an irregular blocky material, indicating that the use of succinic acid promoted the formation of a two-dimensional porous material in the examples.

[0054] As shown in Table 1, the elemental composition of Comparative Example 1 is similar to that of Example 1, both containing Ni, Fe, O, and Br. However, Comparative Example 1 has a smaller specific surface area, only 12.5 m². 2 / g, far lower than in Example 1, indicating that the use of succinic acid is beneficial to the formation of porous structures. Meanwhile, at 10mA cm⁻¹ -2 At the specified current density, the glassy carbon electrode modified with the catalyst in Comparative Example 1 requires an overpotential of 363.9 mV, which is significantly higher than the activity of the catalyst prepared in Example 1 (220.7 mV @ 10 mA cm⁻¹). -2 ) and commercial RuO2 (351.4mV@10mA cm -2 The catalytic activity of the catalyst is poor mainly because the lack of succinic acid makes it prone to sintering during high-temperature calcination, resulting in poor catalyst performance.

[0055] Comparative Example 2

[0056] The difference between Comparative Example 2 and Example 1 is that in step (1), the amount of ethylene glycol used is 0 mg, and the rest of the methods are the same as in Example 1.

[0057] Comparative Example 2 obtained in step (2) was subjected to SEM testing, EDS testing, N2-BET testing, and seawater electrocatalytic oxygen evolution (OER) application. The testing steps and methods were the same as in Example 1. The test results are shown in […]. Figure 6 See Table 1.

[0058] Depend on Figure 6 As can be seen, Comparative Example 2 is a random porous structure composed of small particles, indicating that the use of ethylene glycol is beneficial for the formation of a two-dimensional structure in the examples. This is mainly because ethylene glycol can chelate with succinic acid at high temperatures to form ester compounds. During calcination, the ester compounds generate bubbles and act as templates to promote the formation of two-dimensional structures from the metal oxides.

[0059] As shown in Table 1, the elemental composition of Comparative Example 2 is similar to that of Example 1, both containing Ni, Fe, O, and Br. However, Comparative Example 2 has a smaller specific surface area, only 32.3 m². 2 / g, far lower than in Example 1. Meanwhile, at 10mA cm... -2 At the specified current density, the glassy carbon electrode modified with the catalyst in Comparative Example 2 requires an overpotential of 356.3 mV, which is significantly higher than the activity of the catalyst prepared in Example 1 (220.7 mV @ 10 mA cm⁻¹). -2 ) and commercial RuO2 (351.4mV@10mA cm -2 The catalytic activity of the catalyst is poor mainly because the absence of ethylene glycol causes sintering and the catalyst lacks the structural advantages of two-dimensional materials, resulting in poor catalyst performance.

[0060] Comparative Example 3

[0061] The difference between Comparative Example 3 and Example 1 is that in step (1), the amount of potassium bromide used is 0 mg, and the rest of the methods are the same as in Example 1.

[0062] Comparative Example 3 obtained in step (2) was subjected to EDS test, N2-BET test and seawater electrocatalytic oxygen evolution (OER) application. The test steps and test methods were the same as in Example 1. The test results are shown in Table 1.

[0063] As shown in Table 1, the elemental composition of Comparative Example 3 is Ni, Fe, and O, but it does not contain Br. It has a large specific surface area of ​​58.5 m². 2 / g, similar to the example. Meanwhile, at 10mA cm -2 At the specified current density, the glassy carbon electrode modified with the catalyst in Comparative Example 3 requires an overpotential of 375.1 mV, which is significantly higher than the activity of the catalyst prepared in Example 1 (220.7 mV @ 10 mA cm⁻¹). -2 ) and commercial RuO2 (351.4mV@10mA cm -2 The catalyst's catalytic activity is poor mainly because the lack of bromide ion doping prevents effective improvement in the electronic structure of the catalyst's active sites. Furthermore, the absence of bromide ions hinders the removal of chloride ions from seawater, making the catalyst more susceptible to corrosion by chloride ions, thus resulting in poor catalytic performance.

[0064] Comparative Example 4

[0065] The difference between Comparative Example 4 and Example 1 is that in step (2), the Joule thermal shock heating method is changed to muffle furnace heating. The specific heating conditions are calcination at 900°C for 1 hour in a muffle furnace, with a heating rate of 10°C / min. The rest of the methods are the same as in Example 1.

[0066] Comparative Example 4 obtained in step (2) was subjected to EDS test, N2-BET test and seawater electrocatalytic oxygen evolution (OER) application. The test steps and test methods were the same as in Example 1. The test results are shown in Table 1.

[0067] As shown in Table 1, the elemental composition of Comparative Example 4 is Ni, Fe, and O, but it does not contain Br. This is mainly because Comparative Example 4 uses the traditional muffle furnace calcination technique. Compared to the Joule heating rapid calcination technique used in the examples, the muffle furnace calcination technique has a slower heating and cooling rate, causing the sample to be calcined in an oxygen-rich environment for a long time. This makes it easy for the doped Br ions to be replaced by oxygen in the air, failing to maintain the Br ion-doped structure. In addition, Comparative Example 4 has a small specific surface area of ​​only 15.6 m². 2 / g, mainly due to severe sintering of the material caused by prolonged heating and cooling. Meanwhile, at 10mA cm -2 At the specified current density, the glassy carbon electrode modified with the catalyst in Comparative Example 4 requires an overpotential of 382.4 mV, which is significantly higher than the activity of the catalyst prepared in Example 1 (220.7 mV @ 10 mA cm⁻¹). -2 ) and commercial RuO2 (351.4mV@10mA cm -2 The catalyst's catalytic activity is poor mainly because the catalyst is severely sintered, resulting in fewer exposed active sites. Furthermore, the lack of bromide ion doping prevents effective improvement of the electronic structure of the active sites and the absence of bromide ions blocking chloride ions in seawater, making the catalyst more susceptible to corrosion by chloride ions and thus leading to poor catalytic performance. Comparative Example 5

[0068] The difference between Comparative Example 5 and Example 1 is that in step (2), the Joule thermal shock temperature is changed to 700°C, while the rest of the methods are the same as in Example 1.

[0069] Comparative Example 5 obtained in step (2) was subjected to EDS testing and seawater electrocatalytic oxygen evolution (OER) application. The testing steps and methods were the same as in Example 1, and the test results are shown in Table 1.

[0070] As shown in Table 1, the elemental composition of Comparative Example 5 is Ni, Fe, and O, but it does not contain Br. This is mainly because the thermal shock temperature of Comparative Example 4 is lower, and it did not reach the reaction temperature for bromine doping. Meanwhile, at 10 mA cm⁻¹... -2 At the specified current density, the glassy carbon electrode modified with the catalyst in Comparative Example 5 requires an overpotential of 325.2 mV, which is significantly higher than the activity of the catalyst prepared in Example 1 (220.7 mV @ 10 mA cm⁻¹). -2 ).

[0071] Comparative Example 6

[0072] The difference between Comparative Example 6 and Example 1 is that in step (2), the Joule thermal shock temperature was changed to 1500℃, while the rest of the methods were the same as in Example 1. Comparative Example 5 obtained in step (2) was subjected to EDS test, N2-BET test, and seawater electrocatalytic oxygen evolution (OER) application. The test steps and test methods were the same as in Example 1, and the test results are shown in Table 1.

[0073] As shown in Table 1, the elemental composition of Comparative Example 6 is Ni, Fe, O, and Br. It has a relatively small specific surface area of ​​34.1 m². 2 / g, mainly because the higher thermal shock temperature of Comparative Example 4 caused catalyst sintering. Meanwhile, at 10mA cm -2 At the specified current density, the glassy carbon electrode modified with the catalyst in Comparative Example 6 requires an overpotential of 301.5 mV, which is significantly higher than the activity of the catalyst prepared in Example 1 (220.7 mV @ 10 mA cm⁻¹). -2 ).

[0074] The N2-BET test and linear sweep voltammetry (LSV) test results of Examples 1-4 and Comparative Examples 1-6, as well as the results of commercial RuO2, are shown in the table below.

[0075]

[0076] As described above, succinic acid, ethylene glycol, and ultrafast Joule heating are all necessary conditions for the formation of bromine-doped two-dimensional nickel-iron oxides. In this invention, succinic acid adsorbs metal ions and undergoes an esterification reaction with ethylene glycol to form a metal-ester mixture. During the rapid heating process of Joule heating, the formed metal-ester mixture undergoes oxidation by nitrate ions and high-temperature pyrolysis to generate a large amount of gas. This gas is then blown into the liquefied metal-ester mixture, acting as a template. Simultaneously, the metal ions react with oxygen in the air and bromide ions in the high-temperature bromide salt, forming bromine-doped two-dimensional nickel-iron oxides on the template surface. During the cooling phase, the rapid cooling function of Joule heating prevents the complete oxidation of the bromine-doped two-dimensional nickel-iron oxides. Without succinic acid and ethylene glycol, a two-dimensional porous structure cannot be formed. Furthermore, conventional muffle furnace calcination causes bromine to be completely replaced by oxygen during calcination, preventing the formation of bromide-doped metal oxides and causing catalyst sintering. Compared to undoped two-dimensional nickel-iron oxides and non-two-dimensional layered porous nickel-iron oxides, the bromide-doped two-dimensional porous nickel-iron oxide prepared in this example exhibits superior catalytic activity. This is mainly due to the fact that bromide doping optimizes the electronic structure of the active sites and inhibits the corrosion of the catalyst by chloride ions in seawater. Simultaneously, the two-dimensional porous structure allows for the exposure of more active sites on the catalyst, which is beneficial for gas desorption during the oxygen evolution reaction. Therefore, the prepared catalyst demonstrates excellent performance in the electrolysis of seawater for oxygen evolution.

[0077] The above embodiments are intended to illustrate the essential content of the present invention, but are not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of protection of the present invention.

Claims

1. A method for preparing a bromine-doped two-dimensional nickel-iron oxide, characterized in that, Includes the following steps: (1) Succinic acid, ethylene glycol, ferric nitrate nonahydrate, nickel nitrate hexahydrate, and bromide salt are dissolved in a mixed solution of water and methanol, and stirred under heating conditions until the liquid is completely evaporated to obtain the first solid. (2) The first solid was subjected to Joule thermal shock treatment in air atmosphere, cooled to room temperature, and the resulting solid was washed and dried with deionized water to obtain bromine-doped two-dimensional nickel-iron oxide. In step (2), the Joule thermal shock temperature is 850~1200℃, the heating rate is 1000-2500℃ / s, and the number of Joule thermal shocks is 2~5.

2. The method for preparing bromine-doped two-dimensional nickel-iron oxide according to claim 1, characterized in that, In step (1), the mass ratio of succinic acid, ethylene glycol, ferric nitrate nonahydrate, nickel nitrate hexahydrate, and bromide is 1:0.1~0.2:0.3~0.9:0.3~0.9:5~10; the volume ratio of the mixed solution of succinic acid, water, and methanol is 1mg:0.5~1mL; and the volume ratio of water to methanol is 1:0.3~0.

5.

3. The method for preparing bromine-doped two-dimensional nickel-iron oxide according to claim 1, characterized in that, In step (1), the bromide salt is sodium bromide or potassium bromide.

4. The method for preparing bromine-doped two-dimensional nickel-iron oxide according to claim 1, characterized in that, In step (1), the heating temperature is 130~160℃.

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