Preparation method and application of bromine-doped two-dimensional nickel-iron oxide

Abstract

The invention provides a preparation method and application of bromine-doped two-dimensional nickel-iron oxide, and belongs to the technical field of nano material preparation. The succinic acid, the ethylene glycol, the metal salt and the bromine salt react in the mixed solution, the Joule heat rapid heating and cooling technology is combined, a bromine ion doped two-dimensional porous structure is formed, the method is simple in synthesis process, the prepared catalyst achieves low overpotential and excellent stability in alkaline seawater electrolysis, and the catalyst can be used for preparing the alkaline seawater electrolysis catalyst. The OER reaction efficiency is remarkably improved, and an efficient and durable electrochemical catalyst is provided for a seawater hydrogen production technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterial preparation, and in particular relates to a preparation method of bromine-doped two-dimensional nickel-iron oxide and its application in seawater electrolysis. Background Art

[0002] As a clean energy technology, hydrogen production from seawater electrolysis is of great significance for reducing carbon emissions and promoting a sustainable energy transition. Anode catalysts play a crucial role in this process. Specifically, they can effectively reduce the overpotential of the oxygen evolution reaction, thereby improving electrolysis efficiency. Therefore, the development of efficient, stable, and durable anode catalysts is key to promoting the development of seawater electrolysis hydrogen production technology.

[0003] Among the various anode catalyst materials, nickel iron oxide has become a potential ideal choice due to its adjustable electronic structure and low cost. However, nickel iron oxide still faces some challenges, such as low catalytic activity and susceptibility to chloride ions (Cl - ) and hypochlorite (ClO - ) corrosion, which limits 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 have a large specific surface area, high porosity, and good mass diffusion efficiency, which can provide more active sites. At the same time, the large specific surface area and porosity make the two-dimensional material easier to be modified by heteroatoms, thereby forming a passivation layer on its surface, protecting the anode active sites from Cl - / ClO -Corrosion. Common synthesis methods, such as vapor deposition and wet chemical methods, still have certain limitations. Although the vapor deposition method can precisely control the thickness and morphology of the material, its equipment is expensive and the operation is complicated, which limits its large-scale application. For example, the Chinese patent document with publication number CN117448793A discloses a thin-layer two-dimensional oxide material and its preparation and application. The patent first subjects the substrate to gas plasma treatment, and then chemically vapor deposits the oxide on the substrate, thereby enabling the growth of a thin layer of two-dimensional oxide material. This preparation process has high equipment requirements and high preparation costs, making it unsuitable for large-scale production. Compared with the vapor deposition method, the wet chemical method is favored because of its low cost, simplicity and high efficiency. It is easier to achieve large-scale preparation of nanosheets for layered materials such as layered double hydroxides (LDH), but it still faces great challenges in achieving the preparation of nanosheets of non-layered metal oxides. Most methods rely on templates to promote the formation of two-dimensional structures. For example, Chinese patent publication CN107253701A discloses a method for preparing ultrathin two-dimensional nanomaterials. The patent first disperses a metal salt and graphene oxide in a pre-set buffer solution at the target pH. The process then heats the solution in a liquid phase, washes, and dries the resulting powder, which is then calcined in a muffle furnace to produce the two-dimensional metal oxide. This process is cumbersome, requires the preparation of a buffer solution, and uses graphene oxide as a sacrificial template. This leads to high costs, low efficiency, and poor industrial suitability. Summary of the Invention

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

[0006] To achieve this object, the technical solution of the present invention is: A method for preparing a bromine-doped two-dimensional nickel-iron oxide comprises the following steps: (1) dissolving succinic acid, ethylene glycol, ferric nitrate nonahydrate, nickel nitrate hexahydrate, and bromide in a mixed solution of water and methanol, and stirring under heating until the liquid is completely volatilized to obtain a first solid; (2) The first solid object is placed in a Joule-heated graphite groove and subjected to Joule-heat treatment in an air atmosphere. After cooling to room temperature, the obtained solid is washed with deionized water and dried to obtain a bromine-doped two-dimensional nickel-iron oxide.

[0007] Furthermore, in the step (1), the mass ratio of the succinic acid, ethylene glycol, ferric nitrate nonahydrate, nickel nitrate hexahydrate, and bromide salt is 1:0.1-0.2:0.3-0.9:0.3-0.9:5-10.

[0008] Furthermore, in step (1), the bromide salt is sodium bromide or potassium bromide.

[0009] Furthermore, in step (1), the amount of the mixed solution of succinic acid, water and methanol used is 1 mg:0.5~1 mL; the volume ratio of water to methanol used is 1:0.3~0.5.

[0010] Furthermore, in the step (1), the heating temperature is 130-160°C.

[0011] Furthermore, in step (2), the Joule thermal shock temperature is 850-1200°C, the heating rate is 1000-2500°C / s, and the number of Joule thermal shocks is 2-5 times; the Joule thermal shock is heating from room temperature to the target temperature and then naturally cooling to room temperature, which is represented as one time.

[0012] 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, and to use the two-dimensional nickel-iron oxide as an electrochemical catalyst for OER reaction in alkaline seawater electrolyte.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention combines a wet chemical method with Joule heat rapid temperature rise and fall technology to produce a gas template through the esterification reaction of succinic acid and ethylene glycol, completing the formation of a two-dimensional porous structure and bromine doping in one step. This method does not require a template or a high vacuum environment, the raw materials are easily available, the equipment requirements are low, and the preparation efficiency is significantly improved.

[0014] 2. The present invention uses succinic acid to adsorb metal ions and undergoes an esterification reaction with ethylene glycol to form a metal-ester mixture, which is then subjected to high-temperature oxidation by nitrate ions and high-temperature pyrolysis to form a large amount of gas. A large number of bubbles are blown into the interior of the liquefied metal-ester mixture and serve as a template, thereby promoting the formation of a two-dimensional porous nickel-iron metal oxide.

[0015] 3. The present invention effectively dopes bromide ions into two-dimensional porous nickel-iron oxides through the synergistic effect of bromide salts and Joule heat. During the Joule heat shock process, the high temperature induces bromide ions to replace oxygen ions in the nickel-iron oxide. During the cooling stage, the rapid cooling function of the Joule heat prevents the complete oxidation of the bromine-doped two-dimensional nickel-iron oxide and also inhibits the sintering of the bromine-doped two-dimensional porous nickel-iron oxide.

[0016] 4. Compared with the preparation method of traditional two-dimensional metal oxides, the present invention has high catalytic efficiency, low energy consumption and simple process. In addition, the doping of bromide ions significantly improves the corrosion resistance of nickel-iron oxide and improves the efficiency of its seawater electrocatalytic oxygen evolution (OER) reaction. -2At a current density of 1000 nm, the glassy carbon electrode modified with the catalyst in the example only requires a minimum overpotential of 210.4 mV, which is much lower than that of commercial RuO2 (351.4 mV @ 10 mA cm -2 ), and at 10 mA cm -2 After testing for 100 hours at a current density of , not only did the overpotential hardly increase, but no chlorine evolution reaction occurred. It has excellent electrocatalytic performance and is easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The scanning electron microscope (SEM) image and element distribution (EDS mapping) image of the bromine-doped two-dimensional nickel-iron oxide prepared in Example 1; Figure 2 The nitrogen adsorption-desorption (N2-BET) test results of the bromine-doped two-dimensional nickel-iron oxide prepared in Example 1; Figure 3 The linear sweep voltammetry (LSV) curve of the modified electrode using the bromine-doped two-dimensional nickel-iron oxide prepared in Example 1 as a catalyst; Figure 4 The bromine-doped two-dimensional nickel-iron oxide prepared in Example 1 was used as a catalyst. After modification, the electrode -2 Chronopotentiographs at current density; Figure 5 This is an SEM image of bromine-doped nickel-iron oxide prepared in Comparative Example 1; Figure 6 This is the SEM image of the bromine-doped nickel-iron oxide prepared in Comparative Example 2. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand and implement the present invention, but the protection scope of the present invention is not limited thereto.

[0019] Unless otherwise specified, the 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 meanings as those commonly understood by those skilled in the art.

[0020] In various examples of the present invention, a Joule heating rapid heating device is used, consisting of a gas flow system, a vacuum pump, a graphite sample stage, a temperature control system, and a data acquisition system. The device, model CIS-JH3.3-P, offers 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 time of 1ms. Example 1

[0021] (1) Dissolve 100 mg of succinic acid, 15 mg of ethylene glycol, 45 mg of ferric nitrate nonahydrate, 45 mg of nickel nitrate hexahydrate, and 800 mg of potassium bromide in 70 mL of a mixed solution of water and methanol, and stir at 150° C. until the liquid is completely evaporated to obtain a first solid. The ratio of water to methanol is 1:0.4. (2) 100 mg of the first solid was transferred to a quartz boat (15 mL) fixed in the groove of a graphite hot plate and subjected to Joule thermal shock three times in an air atmosphere at a Joule thermal shock temperature of 1000°C and a heating rate of 1500°C / s. After cooling to room temperature, the resulting solid was washed with deionized water and dried to obtain a bromine-doped two-dimensional nickel-iron oxide, which is recorded as Example 1.

[0022] The Example 1 obtained in step (2) was subjected to SEM test, EDS Mapping test and N2-BET test, and the test results are shown in FIG. Figure 1 and Figure 2 Among them, the pore size distribution test result of N2-BET is the full pore size distribution based on the NLDFT model.

[0023] Depend on Figure 1 It can be seen that the bromine-doped two-dimensional nickel-iron oxide prepared in Example 1 is a flaky structure, in which bromine, iron and nickel are evenly distributed, indicating that the bromine-doped two-dimensional nickel-iron oxide is successfully prepared.

[0024] 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, belonging to a multi-level pore structure of mesopores and macropores, and a specific surface area of 63.4 m 2 / g, and its porous structure is not only conducive to the exposure of active sites, but also to the desorption of product oxygen, thereby improving the OER performance in alkaline seawater electrolysis.

[0025] The bromine-doped two-dimensional nickel-iron oxide catalyst obtained in step (2) is used for seawater electrocatalytic oxygen evolution (OER) application, comprising the following application steps: 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 (a mixture of 0.48 mL of ethanol and 0.02 mL of a 0.5% Nafion solution). After ultrasonic treatment for 2 hours, 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 dripped onto a glassy carbon electrode and naturally air-dried to obtain a bromine-doped two-dimensional nickel-iron oxide catalyst-modified glassy carbon electrode. Electrochemical tests were performed on a CHI760E electrochemical workstation using a bromine-doped two-dimensional nickel-iron oxide catalyst-modified glassy carbon electrode as the working electrode, a graphite rod as the counter electrode, saturated mercury / mercuric oxide as the reference electrode, and a 1 M KOH seawater solution as the electrolyte. Linear sweep voltammetry (LSV) tests and stability tests for the oxygen evolution reaction were performed, and the test results are shown in Table 1. Figure 3 、 Figure 4 Among them, the seawater is taken from the Bohai Sea.

[0026] Depend on Figure 3 It can be seen that at 10 mA cm -2 At a current density of 1000 nm, the glassy carbon electrode modified with the catalyst of Example 1 only requires an overpotential of 210.4 mV, which is much lower than that of commercial RuO2 (351.4 mV@10 mA cm -2 ), which has broad prospects for industrial application.

[0027] Depend on Figure 4 It can be seen that at 10 mA cm -2 After testing for 100 hours at a current density of , the overpotential hardly increased, and ion chromatography did not detect hypochlorite ions in the electrolyte, indicating that the glassy carbon electrode modified with the catalyst in Example 1 mainly carried out OER reaction and did not undergo chlorine evolution reaction, and had excellent stability. Example 2

[0028] (1) Dissolve 100 mg of succinic acid, 10 mg of ethylene glycol, 30 mg of ferric nitrate nonahydrate, 90 mg of nickel nitrate hexahydrate, and 500 mg of potassium bromide in 50 mL of a mixed solution of water and methanol, and stir at 130° C. until the liquid is completely evaporated to obtain a first solid. The ratio of water to methanol is 1:0.3; (2) 100 mg of the first solid was transferred to a quartz boat (15 mL) fixed in a groove on a graphite hot plate and subjected to Joule thermal shock five times in an air atmosphere at a Joule thermal shock temperature of 850°C and a heating rate of 1000°C / s. After cooling to room temperature, the resulting solid was washed with deionized water and dried to obtain a bromine-doped two-dimensional nickel-iron oxide, which was recorded as Example 2.

[0029] The bromine-doped two-dimensional nickel-iron oxide catalyst obtained in step (2) was subjected to elemental composition (EDS) test and N2-BET test and used for seawater electrocatalytic oxygen evolution (OER) application. The test steps and test methods were the same as those in Example 1. The test results are shown in Table 1.

[0030] As shown in Table 1, the elemental composition of Example 2 is similar to that of Example 1, which are Ni, Fe, O, and Br. In addition, Example 2 also has a porous structure with a specific surface area of 72.7 m 2 / g, at 10 mA cm -2 At a current density of 1000 nm, the glassy carbon electrode modified with the catalyst of Example 2 only requires an overpotential of 223.7 mV, which is much lower than that of commercial RuO2 (351.4 mV@10 mA cm -2 ), which has broad prospects for industrial application. Example 3

[0031] (1) Dissolve 100 mg of succinic acid, 20 mg of ethylene glycol, 90 mg of ferric nitrate nonahydrate, 30 mg of nickel nitrate hexahydrate, and 1000 mg of sodium bromide in 100 mL of a mixed solution of water and methanol, and stir at 160° C. until the liquid is completely evaporated to obtain a first solid. The ratio of water to methanol is 1:0.5; (2) 100 mg of the first solid was transferred to a quartz boat (15 mL) fixed in the groove of a graphite hot plate and subjected to Joule thermal shock twice in an air atmosphere at a Joule thermal shock temperature of 1200°C and a heating rate of 2500°C / s. After cooling to room temperature, the resulting solid was washed with deionized water and dried to obtain a bromine-doped two-dimensional nickel-iron oxide, which is recorded as Example 3.

[0032] The bromine-doped two-dimensional nickel-iron oxide catalyst obtained in step (2) was subjected to EDS test and N2-BET test and used for seawater electrocatalytic oxygen evolution (OER) application. The test steps and test methods were the same as those in Example 1. The test results are shown in Table 1.

[0033] As shown in Table 1, the elemental composition of Example 3 is similar to that of Example 1, which are Ni, Fe, O, and Br. In addition, Example 3 also has a porous structure with a specific surface area of 55.3 m 2 / g, at 10 mA cm -2 At a current density of 1000 nm, the glassy carbon electrode modified with the catalyst of Example 2 only requires an overpotential of 242.6 mV, which is much lower than that of commercial RuO2 (351.4 mV@10 mA cm -2 ), which has broad prospects for industrial application. Comparative Example 1

[0034] 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 method is the same as that of Example 1.

[0035] The comparative example 1 obtained in step (2) was subjected to SEM test, EDS test, N2-BET test, and seawater electrocatalytic oxygen evolution (OER) application. The test steps and test methods were the same as those in Example 1. The test results are shown in FIG. Figure 5 and Table 1.

[0036] Depend on Figure 5 It can be seen that Comparative Example 1 is an irregular block material, indicating that the use of succinic acid promotes the formation of a two-dimensional porous material in the example.

[0037] As shown in Table 1, the elemental composition of Comparative Example 1 is similar to that of Example 1, which are Ni, Fe, O, and Br. However, Comparative Example 1 has a smaller specific surface area of only 12.5 m 2 / g, which is much lower than that in Example 1. Therefore, it can be seen that the use of succinic acid is conducive to the formation of porous structure. -2 At a current density of 1000 nm, the glassy carbon electrode modified with the catalyst in Comparative Example 1 requires an overpotential of 363.9 mV, which is much higher than the activity of the catalyst prepared in Example 1 (220.7 mV@10 mA cm -2 ) and commercial RuO2 (351.4 mV@10 mA cm -2 The main reason is that without the use of succinic acid, the catalyst is easily sintered during the high-temperature calcination process, resulting in poor catalyst performance. Comparative Example 2

[0038] 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 Example 1.

[0039] The comparative example 2 obtained in step (2) was subjected to SEM test, EDS test, N2-BET test, and seawater electrocatalytic oxygen evolution (OER) application. The test steps and test methods were the same as those in Example 1. The test results are shown in FIG. Figure 6 and Table 1.

[0040] Depend on Figure 6 Comparative Example 2 shows a random porous structure composed of small particles, indicating that the use of ethylene glycol facilitates the formation of a two-dimensional structure in the example. This is primarily because ethylene glycol can chelate with succinic acid at high temperatures to form an ester compound. During the calcination process, the ester compound generates bubbles that act as a template to promote the formation of a two-dimensional structure in the metal oxide.

[0041] As shown in Table 1, the elemental composition of Comparative Example 2 is similar to that of Example 1, which are Ni, Fe, O, and Br. However, Comparative Example 2 has a smaller specific surface area of only 32.3 m2 / g, which is much lower than that in Example 1. -2 At a current density of 1000 nm, the glassy carbon electrode modified with the catalyst of Comparative Example 2 requires an overpotential of 356.3 mV, which is much higher than the activity of the catalyst prepared in Example 1 (220.7 mV@10 mA cm -2 ) and commercial RuO2 (351.4 mV@10 mA cm -2 This is mainly because without the use of ethylene glycol, the catalyst undergoes certain sintering and lacks the structural advantages of two-dimensional materials, resulting in poor catalyst performance. Comparative Example 3

[0042] 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 method is the same as Example 1.

[0043] 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 those of Example 1. The test results are shown in Table 1.

[0044] As shown in Table 1, the element composition of Comparative Example 3 is Ni, Fe, O, and does not contain Br. It has a large specific surface area of 58.5m 2 / g, close to the example. At the same time, at 10mA cm -2 At a current density of 1000 nm, the glassy carbon electrode modified with the catalyst of Comparative Example 3 required an overpotential of 375.1 mV, which was much higher than the activity of the catalyst prepared in Example 1 (220.7 mV@10 mA cm -2 ) and commercial RuO2 (351.4 mV@10 mA cm -2 The main reason for this is that the electronic structure of the catalyst's active sites has not been effectively improved due to the lack of bromide ion doping. At the same time, the catalyst is more susceptible to corrosion by chloride ions in seawater due to the lack of bromide ions blocking chloride ions in seawater, resulting in poor catalytic performance. Comparative Example 4

[0045] 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 in the muffle furnace for 1 hour, and the heating rate is 10°C / min. The rest of the methods are the same as in Example 1.

[0046] 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 those of Example 1. The test results are shown in Table 1.

[0047] As can be seen from Table 1, the elemental composition of Comparative Example 4 is Ni, Fe, O, and does not contain Br element. This is mainly because Comparative Example 4 uses the traditional muffle furnace calcination technology. Compared with the Joule heat rapid calcination technology used in the examples, the muffle furnace calcination technology has a slower heating rate and cooling rate, which makes the sample calcined in an oxygen-rich environment for a long time. The doped Br ions are easily replaced by oxygen in the air, and the Br ion doping structure cannot be maintained. In addition, Comparative Example 4 has a smaller specific surface area of only 15.6m 2 / g, mainly because the long-term heating and cooling leads to serious sintering of the material. At the same time, at 10mA cm -2 At a current density of 1000 nm, the glassy carbon electrode modified with the catalyst of Comparative Example 4 requires an overpotential of 382.4 mV, which is much higher than the activity of the catalyst prepared in Example 1 (220.7 mV@10 mA cm -2 ) and commercial RuO2 (351.4 mV@10 mA cm -2 ) catalytic activity. This is mainly due to the severe sintering of the catalyst, which exposes fewer active sites. At the same time, the lack of bromide ion doping does not effectively improve the electronic structure of the catalyst's active sites. In addition, the lack of bromide ions blocking the chloride ions in seawater makes the catalyst more susceptible to corrosion by chloride ions in seawater, resulting in poor catalytic performance. Comparative Example 5

[0048] The difference between Comparative Example 5 and Example 1 is that in step (2), the Joule thermal shock temperature is changed to 700° C., and the rest of the methods are the same as those in Example 1.

[0049] Comparative Example 5 obtained in step (2) was subjected to EDS testing and seawater electrocatalytic oxygen evolution (OER) application. The testing steps and testing methods were the same as those in Example 1. The test results are shown in Table 1.

[0050] As shown in Table 1, the element composition of Comparative Example 5 is Ni, Fe, O, and does not contain Br. This is mainly because the thermal shock temperature of Comparative Example 4 is too low to reach the reaction temperature of bromine doping. -2 At a current density of 1000 nm, the glassy carbon electrode modified with the catalyst of Comparative Example 5 requires an overpotential of 325.2 mV, which is much higher than the activity of the catalyst prepared in Example 1 (220.7 mV@10 mA cm -2 ). Comparative Example 6

[0051] The difference between Comparative Example 6 and Example 1 is that in step (2), the Joule thermal shock temperature is changed to 1500° C., and the rest of the methods are 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 are the same as in Example 1. The test results are shown in Table 1.

[0052] As shown in Table 1, the element composition of Comparative Example 6 is Ni, Fe, O, and Br. It has a smaller specific surface area of 34.1 m 2 / g, mainly because the thermal shock temperature of Comparative Example 4 was higher, causing the sintering of the catalyst. -2 At a current density of 1000 nm, the glassy carbon electrode modified with the catalyst of Comparative Example 6 requires an overpotential of 301.5 mV, which is much higher than the activity of the catalyst prepared in Example 1 (220.7 mV@10 mA cm -2 ).

[0053] The N2-BET test and linear sweep voltammetry (LSV) test results of Examples 1-4 and Comparative Examples 1-6, as well as the commercial RuO2, are shown in the following table:

[0054] As can be seen from the above, succinic acid, ethylene glycol, and ultrafast Joule heat calcination are all necessary conditions for forming bromine-doped two-dimensional nickel-iron oxide. In the present invention, succinic acid adsorbs metal ions and undergoes an esterification reaction with ethylene glycol to form a metal-lipid mixture. During the rapid Joule heat heating process, the formed metal-ester mixture is oxidized by nitrate ions and pyrolyzed at high temperature to form a large amount of gas, blowing out a large number of bubbles inside the liquefied metal-ester mixture and serving as a template. At the same time, the metal ions react with oxygen in the air and bromide ions in the high-temperature bromine salt to form a bromine-doped two-dimensional nickel-iron metal oxide on the template surface. During the cooling stage, the rapid cooling function of the Joule heat prevents the complete oxidation of the bromine-doped two-dimensional nickel-iron oxide. If succinic acid and ethylene glycol are not used, the two-dimensional porous structure cannot be formed. At the same time, traditional muffle furnace calcination will cause the bromine element to be completely replaced by oxygen during the calcination process, preventing the formation of bromide-doped metal oxide and causing the catalyst to sinter. Compared to two-dimensional nickel-iron oxide without bromide ion doping and non-two-dimensional layered porous nickel-iron metal oxide, the bromide ion-doped two-dimensional porous nickel-iron oxide prepared in the examples has better catalytic activity. This is mainly because bromide ion doping can optimize the electronic structure of the active sites and inhibit the corrosion of chloride ions in seawater on the catalyst. At the same time, the two-dimensional porous structure helps the catalyst expose more active sites and facilitates the desorption of gas in the oxygen evolution reaction. Therefore, the prepared catalyst exhibits excellent performance in the electrolysis of seawater for oxygen evolution reaction.

[0055] 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 the technical solutions of the present invention can be modified or replaced by equivalents without departing from the essence and scope of protection of the technical solutions of the present invention.

Claims

1. A method for preparing bromine-doped two-dimensional nickel-iron oxide, characterized in that: The following steps are involved: (1) dissolving succinic acid, ethylene glycol, ferric nitrate nonahydrate, nickel nitrate hexahydrate, and bromide in a mixed solution of water and methanol, and stirring under heating conditions until the liquid is completely volatilized to obtain a first solid; (2) The first solid material is subjected to Joule thermal shock treatment in an air atmosphere, cooled to room temperature, and the obtained solid is washed with deionized water and dried to obtain a bromine-doped two-dimensional nickel-iron oxide.

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

4. The method for preparing bromine-doped two-dimensional nickel-iron oxide according to claim 1, wherein: In the step (1), the heating temperature is 130-160°C.

5. The method for preparing bromine-doped two-dimensional nickel-iron oxide according to claim 1, wherein: In the step (2), the Joule thermal shock temperature is 850-1200°C, the heating rate is 1000-2500°C / s, and the number of Joule thermal shocks is 2-5 times.

6. Use of a bromine-doped two-dimensional nickel-iron oxide prepared by the preparation method according to any one of claims 1 to 4, characterized in that: The bromine-doped two-dimensional nickel-iron oxide is used as an electrochemical catalyst in the oxygen evolution reaction in alkaline seawater electrolyte.

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