A preparation method of Ru-RuO2 nanosheets and its application

Abstract

The present invention provides a preparation method and application of Ru-RuO2 nanosheets, belonging to the technical field of nanomaterial preparation. The present invention first adds L-proline, ruthenium trichloride trihydrate, and urea to ethanol, ultrasonically dissolves them, and then heats them to form a colloidal liquid, and then performs Joule heat treatment under an air atmosphere to obtain Ru-RuO2 nanosheets. This method does not require surfactants, templates, reducing atmospheres, and complex calcination processes, and can achieve the preparation of porous heterojunction Ru-RuO2 nanosheets with high efficiency and low energy consumption, and has prospects for industrial application. This two-dimensional porous heterojunction formed by in-situ calcination has a rich interface structure, can give full play to the synergistic effect of the two components, and significantly improves its activity and stability in acidic water electrolysis applications.

Description

Technical Field

[0001] The invention belongs to the technical field of nano material preparation, and particularly relates to a preparation method of Ru-RuO2 nanosheets and application thereof in acidic electrolyzed water. Background Art

[0002] Hydrogen production through water electrolysis has attracted widespread attention in recent years as a green and sustainable method for hydrogen production. With the global energy crisis and environmental pollution becoming increasingly severe, hydrogen energy is considered a crucial component of future clean energy. Water electrolysis not only produces hydrogen through the conversion of water and electricity, but its use in fuel cells can also effectively reduce greenhouse gas emissions. Therefore, improving the efficiency of water electrolysis and promoting its large-scale application are key to the current energy transition and green economic development.

[0003] The oxygen evolution reaction (OER) catalysts used at the anode of proton exchange membrane water electrolysis (PEMWE) rely heavily on Ir-based catalysts, resulting in high costs. RuO2 catalysts have attracted considerable attention due to their higher OER activity and lower cost. However, RuO2 readily oxidizes to the more highly active RuO4, which dissolves in highly corrosive electrolytes, resulting in poor stability and limiting its application in PEMWE.

[0004] Constructing a two-dimensional heterojunction Ru-RuO2 can optimize the electronic structure of the Ru site, improve the stability and dissolution energy barrier of the Ru atom, and provide a very large surface area and 2D permeation channels for ion adsorption and transport, thereby exhibiting excellent catalytic performance. However, the current preparation of Ru-RuO2 nanosheets mainly relies on wet chemical methods, step-by-step calcination methods, or a combination of wet chemical methods and calcination methods. Wet chemical synthesis methods often require surfactants to control the particle morphology. The residual surfactant in the catalyst will block the catalytic sites, reduce the catalytic activity, and require additional cleaning processes. In addition, the atomic utilization rate of wet chemical methods is lower than that of calcination methods, which brings difficulties to the industrialization of wet chemical methods. The step-by-step calcination method often requires the use of templates to control the morphology of the catalyst, and requires the distribution of reducing and oxidizing atmospheres to control the phase composition of the catalyst during calcination. This method also faces low scalability.

[0005] The Chinese invention patent document with publication number CN116288495A discloses an amorphous Ru-RuO x Preparation method and application of composite nanoparticle catalyst. The invention first prepares carbon nitride carrier by high temperature calcination, and then prepares amorphous Ru-RuO by impregnation, calcination in hydrogen and argon atmosphere, and high temperature oxidation. xThe preparation process of this catalyst is relatively complicated, requiring liquid phase impregnation and calcination in different atmospheres, which is time-consuming and energy-consuming and is not conducive to industrial production.

[0006] A Chinese invention patent document, publication number CN117535725A, discloses a RuO2@Ru flower-shaped nanosphere electrocatalyst grown on nickel foam, its preparation method, and applications. The invention first treats nickel foam with a ruthenium source solution and conducts two hydrothermal reactions to obtain ruthenium-deposited nickel foam. This is then followed by an oxidative annealing treatment to produce the nickel foam-supported RuO2@Ru flower-shaped nanosphere electrocatalyst. This preparation process requires two hydrothermal steps and a single calcination step, making it relatively complex and unsuitable for industrial production. Furthermore, the process relies on nickel foam as a reducing support, making it suitable only for preparing nickel foam-supported RuO2@Ru and unsuitable for preparing powdered RuO2@Ru.

[0007] The Chinese invention patent document with publication number CN118356965A discloses a method for preparing a Ru / RuO2-S-C3N4 catalyst and its application. The invention first prepares S-C3N4 by high-temperature pyrolysis of thiosemicarbazide, then impregnates ruthenium chloride with a mass ratio of 1wt% to 3wt% of S-C3N4 and then calcines it to prepare Ru / RuO2-S-C3N4. 2- This process not only requires multiple reaction steps, but also results in a low Ru content in the Ru / RuO2-S-C3N4 catalyst. XRD results show no characteristic peaks for Ru and RuO2. This indicates that the catalyst is primarily composed of S-C3N4 and is unsuitable for the preparation of Ru-based catalysts.

[0008] Chinese invention patent publication number CN119287416A discloses a method for preparing Ru-RuO2 core-shell nanosheets via a gas-solid phase reaction. This method first adsorbs a soluble Ru salt onto a surface-functionalized support, then reduces the Ru nanosheets under an inert atmosphere to produce the Ru-RuO2 core-shell nanosheets. Finally, the Ru nanosheets are partially oxidized to produce the Ru-RuO2 core-shell nanosheets. This process involves support functionalization and staged reduction and oxidation treatments, resulting in a complex catalyst preparation process and high costs, making it unsuitable for industrial production. Summary of the Invention

[0009] The purpose of the present invention is to provide a method for preparing Ru-RuO2 nanosheets. The present invention realizes the efficient synthesis of Ru-RuO2 nanosheets through the coordinated regulation of L-proline, urea and ethanol, combined with a one-step Joule heat treatment process. The method is simple in process and low in preparation cost. The prepared catalyst has a large specific surface area, a low overpotential in acidic electrolysis water, and excellent cycle stability, thereby providing a high-efficiency catalyst for industrial water electrolysis hydrogen production.

[0010] To achieve this object, the technical solution of the present invention is:

[0011] A method for preparing Ru-RuO2 nanosheets comprises the following steps:

[0012] (1) L-proline, ruthenium trichloride trihydrate, and urea were added to ethanol, dissolved by ultrasonication, and heated and stirred to obtain a colloidal liquid;

[0013] (2) The colloidal liquid is placed in a quartz crucible and placed in the groove of a graphite sample stage of a Joule heat rapid heating device. Ru-RuO2 nanosheets are obtained after Joule heat treatment in an air atmosphere.

[0014] Furthermore, in the step (1), the ratio of the amount of L-proline, ruthenium trichloride trihydrate, urea, and ethanol is 1 g: 1-1.5 g: 1.3-1.7 g: 6-8 mL;

[0015] Furthermore, in step (1), the ultrasonic treatment power is 80-100W, and the ultrasonic treatment time is 0.5-2h.

[0016] Furthermore, in step (1), the heating temperature is 50-80° C., and the heating time is 6-10 hours.

[0017] Furthermore, in step (2), the Joule thermal shock temperature is 500-800°C, the heating rate is 1500-2000°C / s, and the number of Joule thermal shocks is 1-5 times. The Joule thermal shock is heating from room temperature to the target temperature and then naturally cooling to room temperature, which is represented by one time.

[0018] Another object of the present invention is to provide an application of the Ru-RuO2 nanosheet catalyst prepared by the above method, which is used as an electrochemical catalyst in the oxygen evolution reaction (OER) under acidic conditions.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention adopts ethanol to form reducing steam in the reaction, which can effectively prevent the Ru-RuO2 nanosheets from being completely oxidized during the calcination reaction in the air atmosphere, so that the Ru-RuO2 can exist stably.

[0021] The present invention adopts the synergistic effect of L-proline, urea and Joule heat, and can directly prepare a two-dimensional porous heterojunction Ru-RuO2 through a simple solid-phase calcination method. Urea, L-proline and ruthenium ions can form metal chelates in an ethanol solvent system. At the same time, the chelates formed by urea can lock ethanol molecules to form a colloidal liquid containing ethanol. During the Joule heat shock process of these colloidal liquids in an air atmosphere, the internal ethanol is heated to produce bubbles and reducing vapor, and urea and L-proline react with carbonylamine to form a slurry and produce bubbles. These bubbles can be pyrolyzed to form a carbon template to reduce part of the ruthenium ions to Ru elemental substances, while the other part of the Ru ions combine with oxygen in the air to form RuO2, thereby obtaining a two-dimensional porous Ru-RuO2 heterojunction, i.e., a Ru-RuO2 nanosheet. The thickness of the nanosheet is relatively thin, about 20nm, and the specific surface area is 48.63-55.23 m 2 / g is large, which allows it to expose more active sites as a catalyst, significantly promoting the activity and stability of the catalytic reaction.

[0022] Compared with traditional wet chemical and step-by-step calcination methods, the technical solution provided by the present invention does not require surfactants and templates, does not require reducing atmosphere and complex calcination processes, can achieve the preparation of Ru-RuO2 nanosheets with high efficiency and low energy consumption, and has greater industrial application prospects.

[0023] The technical solution provided by the present invention, the Ru-RuO2 nanosheets formed by in-situ calcination have rich interface structures, which can give full play to the synergistic effect of the two components and significantly improve their activity and stability in acidic water electrolysis applications. -2 The maximum overpotential required at the current density is only 165.3mV, which is much lower than that of commercial RuO2 (308.5mV@10mA cm -2 ), and there was no obvious performance degradation in Example 1 after the cycle stabilization time of 100 h, showing excellent electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 X-ray powder diffraction (XRD) pattern of the sample of Example 1;

[0025] Figure 2 SEM image of the sample from Example 1;

[0026] Figure 3 Nitrogen adsorption and desorption (N2-BET) diagram of the sample in Example 1;

[0027] Figure 4 SEM image of the sample of Comparative Example 1;

[0028] Figure 5SEM image of the sample of Comparative Example 3;

[0029] Figure 6 SEM image of the sample of Comparative Example 5;

[0030] Figure 7 Linear sweep voltammetry (LSV) curve of the modified electrode using Ru-RuO2 nanosheets prepared in Example 1 as catalyst;

[0031] Figure 8 The Ru-RuO2 nanosheets prepared in Example 1 were used as catalysts. After modification, the electrode -2 Chronopotentiographs at different current densities. DETAILED DESCRIPTION

[0032] 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.

[0033] Unless otherwise specified, the raw materials used in the embodiments of the present invention are all 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.

[0034] 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.

[0035] Example 1

[0036] (1) Add 2 g of L-proline, 2.6 g of ruthenium trichloride trihydrate, and 3 g of urea to 15 mL of ethanol, sonicate for 1 h at 90 W power to dissolve, and then stir at 70 ° C for 8 h to obtain a colloidal liquid;

[0037] (2) 5 mL of colloidal liquid was placed in a 20 mL quartz crucible and placed in the groove of the graphite sample stage of a Joule heat rapid heating device. Joule heat shock was performed three times in an air atmosphere at a Joule heat shock temperature of 650 °C and a heating rate of 1700 °C / s. Finally, Ru-RuO2 nanosheets were obtained, which were recorded as the sample of Example 1.

[0038] The Ru-RuO2-1 prepared in step (2) was subjected to XRD test, SEM test and N2-BET test. The test results are shown in Figure 1 , Figure 2 and Figure 3 .

[0039] Depend on Figure 1 It can be seen that the characteristic diffraction peaks of the sample of Example 1 correspond to the standard cards of Ru and RuO2 (Ru PDF#01-088-1734 and RuO2 PDF#00-043-1027), indicating that Example 1 is a heterojunction composed of Ru and RuO2.

[0040] Depend on Figure 2 It can be seen that Example 1 presents a two-dimensional porous nanosheet structure, and the thickness of the nanosheet is about 20 nm.

[0041] Depend on Figure 3 It can be seen that Example 1 is a porous material rich in mesopores.

[0042] Example 2

[0043] (1) Add 2 g of L-proline, 2 g of ruthenium trichloride trihydrate, and 2.6 g of urea to 12 mL of ethanol, sonicate for 0.5 h at 100 W power to dissolve, and then stir at 50 ° C for 10 h to obtain a colloidal liquid;

[0044] (2) 5 mL of colloidal liquid was placed in a 20 mL quartz crucible and placed in the groove of the graphite sample stage of a Joule heat rapid heating device. Joule heat shock was performed once in an air atmosphere at a Joule heat shock temperature of 800 °C and a heating rate of 1500 °C / s. Finally, Ru-RuO2 nanosheets were obtained, which were recorded as the sample of Example 2.

[0045] The sample of Example 2 was subjected to XRD and N2-BET tests using the same testing methods as in Example 1. The test results are shown in Table 1. It can be seen that the sample of Example 2 is similar to the sample of Example 1, both having a porous structure composed of Ru and RuO2.

[0046] Example 3

[0047] (1) 2 g of L-proline, 3 g of ruthenium trichloride trihydrate, and 3.4 g of urea were added to 16 mL of ethanol, sonicated at 80 W for 2 h to dissolve, and then stirred at 80 ° C for 6 h to obtain a colloidal liquid;

[0048] (2) 5 mL of colloidal liquid was placed in a 20 mL quartz crucible and placed in the groove of the graphite sample stage of a Joule heat rapid heating device. Joule heat shock was performed 5 times in an air atmosphere. The Joule heat shock temperature was 500 °C and the heating rate was 2000 °C / s. Finally, Ru-RuO2 nanosheets were obtained, which were recorded as the sample of Example 3.

[0049] The sample of Example 3 was subjected to XRD test and N2-BET test, and the test method was the same as that of Example 1. The test results are shown in Table 1. It can be seen that the sample of Example 3 is similar to the sample of Example 1, and both are porous structures composed of Ru and RuO2.

[0050] Comparative Example 1

[0051] (1) Add 2 g of L-proline, 2.6 g of ruthenium trichloride trihydrate, and 3 g of urea to 15 mL of ethanol, dissolve them by ultrasonication at 90 W power for 1 h, and then stir and react at 100 ° C for 20 h. The ethanol is completely evaporated to obtain a dry solid.

[0052] (2) 10 mg of the above solid was placed in a 20 mL quartz crucible and placed in the groove of the graphite sample stage of a Joule heat rapid heating device. Joule heat shock was performed three times in an air atmosphere at a Joule heat shock temperature of 650 ° C and a heating rate of 1700 ° C / s to obtain the comparative example 1 sample.

[0053] The sample of comparative example 1 prepared in step (2) was subjected to XRD test, SEM test and N2-BET test. The test method was the same as that of Example 1. The test results are shown in FIG. Figure 4 and Table 1.

[0054] Depend on Figure 4 It can be seen that the sample of Comparative Example 1 is a porous structure composed of nanoparticles rather than a sheet structure. At the same time, it can be seen from Table 1 that the phase composition of the sample of Comparative Example 1 is pure RuO2 with a specific surface area of ​​34.58 m 2 / g, which is smaller than the specific surface area of ​​the sample in Example 1 (52.14m 2 / g). This is mainly because, compared with Comparative Example 1, the substance calcined in Example 1 is a colloidal liquid containing ethanol, and in Comparative Example 1, the ethanol is completely volatilized because the heating temperature and time in step (1) are longer. During the Joule heat calcination process, the ethanol locked in the colloid by urea quickly boils and escapes from the colloidal substance, which not only serves as a foaming agent and template to form a two-dimensional porous structure inside the colloidal substance, but also forms a reducing atmosphere, which together with the carbon produced by the pyrolysis of L-proline reduces part of the ruthenium ions to form a ruthenium element. In addition, the ethanol vapor can also prevent the formed ruthenium element from being completely oxidized. The other part of the ruthenium ions will react with the oxygen inside the reaction chamber to form ruthenium oxide, and together with the generated ruthenium element, form a heterojunction nanosheet.

[0055] Comparative Example 2

[0056] The difference between Comparative Example 2 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 650°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 those in Example 1.

[0057] The sample of comparative example 2 prepared in step (2) was subjected to XRD test and N2-BET test. The test method was the same as that of Example 1. The test results are shown in Table 1.

[0058] It can be seen from Table 1 that the phase composition of the sample of Comparative Example 2 is pure RuO2, and the specific surface area is 22.25 m 2 / g, which is much smaller than the specific surface area of ​​the sample in Example 1 (52.14m 2 This is primarily due to the slow heating and cooling processes of traditional muffle furnace calcination, which exposes the sample to air, leading to complete oxidation and the failure to form a metallic ruthenium phase. Furthermore, prolonged calcination in air easily leads to sintering, resulting in a smaller specific surface area.

[0059] Comparative Example 3

[0060] The difference between Comparative Example 3 and Example 1 is that urea is not used in step (1), and the rest of the method is the same as that of Example 1.

[0061] The sample of comparative example 3 prepared in step (2) was subjected to XRD test, SEM test and N2-BET test. The test methods were the same as those in Example 1. The test results are shown in Table 1.

[0062] Test results see Figure 5 and Table 1.

[0063] Depend on Figure 5 It can be seen that the sample of Comparative Example 3 is mainly a rough and porous block structure rather than a sheet structure. At the same time, it can be seen from Table 1 that the phase composition of the sample of Comparative Example 3 is pure RuO2 with a specific surface area of ​​29.26 m 2 / g, which is much smaller than the specific surface area of ​​the sample in Example 1 (52.14m 2 / g). This is primarily due to the chelation of urea with metal salts to form a colloid, locking the ethanol solvent within the colloid. Without the addition of urea, the ethanol cannot be locked within the colloid. Furthermore, urea reacts with L-proline under heating to form a carbonylamine-like slurry. The heated bubbles act as carbon templates, providing growth and nucleation sites for the formation of Ru-RuO2 nanosheets.

[0064] Comparative Example 4

[0065] The difference between Comparative Example 4 and Example 1 is that in step (2), the Joule heat shock atmosphere is argon, and the rest of the methods are the same as those in Example 1.

[0066] The sample of comparative example 4 prepared in step (2) was subjected to XRD test and N2-BET test. The test method was the same as that of Example 1. The test results are shown in Table 1. It can be seen that the phase composition of the sample of comparative example 4 is pure Ru, and the specific surface area is 55.35 m 2 / g, compared with the specific surface area of ​​the sample in Example 1 (52.14m 2 The reason why RuO2 is not formed is mainly because the inert atmosphere cannot provide an oxidizing environment.

[0067] Comparative Example 5

[0068] The difference between Comparative Example 5 and Example 1 is that L-proline is not used in step (1), and the rest of the method is the same as that of Example 1.

[0069] The prepared comparative example 5 sample was subjected to XRD test, SEM test and N2-BET test. The test method was the same as that of Example 1. The test results are shown in Figure 6 and Table 1.

[0070] Depend on Figure 6 It can be seen that the sample of comparative example 5 mainly presents a large block structure. At the same time, it can be seen from Table 1 that the phase composition of the sample of comparative example 5 is pure RuO2, and the specific surface area is 18.38 m 2 / g, which is much smaller than the specific surface area of ​​Example 1 (52.14m 2 / g), indicating that L-proline plays a crucial role in the physical phase and morphology of the prepared material. This is primarily due to L-proline's ability to chelate ruthenium particles and, upon heating, to form a carbonylamine reaction with urea, forming a slurry. The heated bubbles act as a carbon template, reducing some Ru ions to elemental Ru while also providing growth and nucleation sites for the formation of Ru-RuO2 nanosheets.

[0071] Comparative Example 6

[0072] The difference between Comparative Example 6 and Example 1 is that in step (2), the Joule heat shock temperature is changed to 300° C., and the rest of the methods are the same as those in Example 1.

[0073] The prepared comparative example 6 sample was subjected to N2-BET test using the same test method as in Example 1. The test results are shown in Table 1. As can be seen from Table 1, the specific surface area of ​​the comparative example 6 sample is 19.31 m 2 / g, which is much smaller than the specific surface area of ​​the sample in Example 1 (52.14m 2 / g), which is mainly due to the low Joule thermal shock temperature in the comparative example, resulting in incomplete decomposition of the colloidal substance.

[0074] Comparative Example 7

[0075] The difference between Comparative Example 7 and Example 1 is that in step (2), the Joule thermal shock temperature is changed to 1000°C, and the rest of the methods are the same as those in Example 1. The prepared Comparative Example 7 was subjected to N2-BET test using the same test method as in Example 1. The test results are shown in Table 1. As can be seen from Table 1, the specific surface area of ​​the sample in Comparative Example 7 is 36.48 m 2 / g, which is much smaller than the specific surface area of ​​Example 1 (52.14m 2 / g), mainly because the Joule thermal shock temperature in Comparative Example 7 was too high, resulting in sintering of Ru-RuO2 nanosheets.

[0076] Application Example 1

[0077] 4 mg of the catalyst prepared in the embodiment or comparative example or commercial RuO2 and 1 mg of commercial carbon black were added to an ethanol-Nafin mixed solution (a mixture of 0.48 mL of ethanol and 0.02 mL of a 0.5% Nafin solution), and after ultrasonic treatment for 2 h, a uniformly dispersed catalyst solution was obtained; 0.01 mL of the catalyst solution was measured using a pipette and dropped onto a glassy carbon electrode, and the glassy carbon electrode modified with the catalyst was obtained after natural air drying; electrochemical tests were performed on a CHI760E electrochemical workstation using the catalyst-modified glassy carbon electrode as the working electrode, a graphite rod as the counter electrode, a saturated calomel as the reference electrode, and a 0.1 M HClO4 aqueous solution as the electrolyte to perform linear sweep voltammetry (LSV) tests of the oxygen evolution reaction. The test results are shown in FIG. Figure 7 , Figure 8 and Table 1.

[0078] The LSV test, XRD test (phase composition), and N2-BET (specific surface area) test results of Examples 1-3, Comparative Examples 1-5, and commercial RuO2 are shown in Table 1:

[0079]

[0080] Depend on Figure 6 , Figure 7 As can be seen from Table 1, the Ru-RuO2 nanosheets prepared in Example 1 are used as catalysts, and the modified electrode has an -2 The maximum overpotential required at the current density is only 165.3 mV, among which the Ru-RuO2 nanosheets prepared in Example 1 only require 161.8 mV, which is much lower than the commercial RuO2 (308.5 mV @ 10 mA cm -2 ) and other comparative examples, except for Figure 8It can be seen that the Ru-RuO2 nanosheets prepared in Example 1 do not show obvious performance degradation after the cycle stability time of 100h, indicating that the Ru-RuO2 nanosheets prepared in Example 1 have excellent catalytic activity and stability, and have more industrial application prospects. This excellent performance is mainly derived from the morphology and component advantages of the embodiment. Its morphology and structural advantage is a two-dimensional porous structure, which makes it have a larger specific surface area so as to expose more active sites and facilitate the desorption of product oxygen. The structural advantage is that the heterojunction has a rich interface structure, which can give full play to the synergistic effect of the two components. The morphology and component analysis of the samples of Examples 1-3 and Comparative Examples 1-5 can infer that the reason why the embodiment forms a two-dimensional porous heterojunction is mainly urea and ruthenium ions. L-proline and ruthenium ions all form metal chelates in the ethanol solvent system, and the chelate formed by urea can lock the ethanol molecules and form a colloidal liquid containing ethanol together with these chelates under heating. During the Joule heat shock process of these colloidal liquids under an air atmosphere, the internal ethanol is heated to produce bubbles and reducing vapors, and urea and L-proline undergo a carbonyl-ammonia reaction to form a slurry and produce bubbles. These bubbles can, on the one hand, be pyrolyzed to form a carbon template that reduces some ruthenium ions to elemental Ru, and on the other hand, provide growth and nucleation sites for the formation of Ru-RuO2. At the same time, the external ethanol atmosphere can inhibit the complete oxidation of Ru by air, allowing Ru-RuO2 to exist stably. Therefore, in this preparation scheme, the colloidal liquid containing ethanol, the Joule heat of the air atmosphere, urea, and L-proline are all essential conditions for the formation of Ru-RuO2 nanosheets. As can be seen from the catalytic effects of the sample in Example 1 and the samples in Comparative Examples 6 and 7, both too high and too low Joule heat shock temperatures are detrimental to the catalytic performance of the examples. Too low a shock temperature will prevent the colloidal material from completely decomposing, while too high a shock temperature will cause the Ru-RuO2 nanosheets to sinter. Too low or too high a shock temperature will both lead to reduced catalyst activity.

[0081] 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 Ru-RuO2 nanosheets, characterized in that: The following steps are involved: (1) L-proline, ruthenium trichloride trihydrate, and urea are ultrasonically dissolved in ethanol, heated and stirred to react to obtain a colloidal liquid; (2) The colloidal liquid is placed in a quartz crucible and subjected to Joule heat treatment in an air atmosphere to obtain a two-dimensional porous Ru-RuO2 heterojunction, i.e., Ru-RuO2 nanosheets; In the step (1), the ratio of L-proline, ruthenium trichloride trihydrate, urea, and ethanol is 1 g: 1-1.5 g: 1.3-1.7 g: 6-8 mL; In the step (2), the Joule thermal shock temperature is 500-800°C, the heating rate is 1500-2000°C / s, and the number of Joule thermal shocks is 1-5 times.

2. The method for preparing Ru-RuO2 nanosheets according to claim 1, wherein In the step (1), the power of the ultrasonic treatment is 80-100 W, and the ultrasonic treatment time is 0.5-2 h.

3. The method for preparing Ru-RuO2 nanosheets according to claim 1, wherein In the step (1), the heating and stirring reaction conditions are: heating temperature 50-80°C, heating time 6-10h.

4. An application of Ru-RuO2 nanosheets prepared by the method according to any one of claims 1 to 3, characterized in that: The Ru-RuO2 nanosheets are used as electrochemical catalysts for oxygen evolution reaction in an acidic electrolyte.

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