Oxide nanosheet as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalyst preparation, in particular to an oxide nanosheet and a preparation method and application thereof. According to the preparation method provided by the invention, the reaction materials are mixed according to a specific molar ratio and calcined to a molten salt state, the obtained oxide nanosheet has good sheet structure characteristics, relatively high crystallinity and a stable crystal phase, the catalytic performance of the material is effectively enhanced, the potential of practical application in hydrogen production through water electrolysis is achieved, and the preparation method is suitable for industrial production. The catalytic activity can be further enhanced after boric acid modification; the process is simple, and large-scale preparation is facilitated. In the test provided by the invention, the IrOx nanosheet prepared by the invention has a stable rutile crystal phase structure, is relatively high in crystallinity and stable in crystal phase, and has certain performance in a water electrolysis device; the IrOx-H3BO3 modified by boric acid also has a rutile crystal phase structure, is relatively high in crystallinity and stable in crystal phase, and has better performance in a water electrolysis device compared with IrOx.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and specifically to oxide nanosheets, a preparation method thereof, and an application thereof. Background Art

[0002] The proton exchange membrane water electrolysis hydrogen production technology can be well coupled with renewable and fluctuating energy sources (such as wind energy, solar energy, tidal energy), and convert the electricity that is difficult to be grid-connected into the chemical energy of high-purity hydrogen that can be transported through long-distance pipelines and stored for a long time. At present, due to the need to withstand strong acidity and high oxidation potential on the anodic oxygen evolution catalyst side of the proton exchange membrane water electrolysis hydrogen production technology, there are few active materials that can be used as the anodic oxygen evolution catalyst for a long time at a large current density. Moreover, due to the slow kinetics of the oxygen evolution reaction, there are even fewer highly active materials that can be used as the anodic oxygen evolution catalyst for a long time at a large current density. In addition, relatively stable materials (iridium metal and iridium oxide) belong to precious metal materials, which increases the use cost of the proton exchange membrane water electrolysis hydrogen production technology and limits its industrial scale-up.

[0003] In order to obtain materials with higher activity and lower use cost, improving the utilization rate of active sites of relatively stable materials is a commonly adopted strategy. Flaky structure materials usually have a larger specific surface area and a higher utilization rate of active sites compared to particulate structure materials that are prone to agglomeration. However, the crystallinity of the flaky structure materials with a stable crystal phase structure prepared by the prior art and applicable to the proton exchange membrane water electrolysis hydrogen production technology is generally low, and cannot meet the performance requirements of the catalytic materials as the anodic oxygen evolution catalyst in the proton exchange membrane water electrolysis hydrogen production technology. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide oxide nanosheets, a preparation method thereof, and an application thereof. The preparation method provided by the present invention can prepare oxide nanosheets with high crystallinity, having a stable oxide crystal phase, and having high catalytic activity and stability in water electrolysis hydrogen production.

[0005] The present invention provides a preparation method of oxide nanosheets, including the following steps:

[0006] Calcining solid particles of a metal source, solid particles of a nitrate, and solid particles of boric acid with a molar ratio of 1:(10-1000):(0-100), and washing the calcined product to obtain oxide nanosheets;

[0007] The metal source includes one or more of an Ir source, a Ru source, a Co source, and a Mn source.

[0008] The molar ratio of the metal source solid particles, nitrate solid particles and boric acid solid particles in the present invention is 1:(10-1000):(0-100), that is, a stable crystalline phase oxide nanosheet with high crystallinity can be obtained in the present invention without adding boric acid solid particles, which is sufficient for use in hydrogen production by water electrolysis.

[0009] Preferably, the molar ratio of the metal source solid particles, nitrate solid particles and boric acid solid particles in the present invention is 1:(10-1000):(0.1-100). In the present invention, when boric acid solid particles are added, not only a stable crystalline phase oxide nanosheet with high crystallinity can be obtained, but also significantly higher catalytic activity can be achieved.

[0010] In the metal source solid particles of the present invention, the metal source includes one or more of an Ir source, a Ru source, a Co source, and a Mn source; the metal source includes one or more of a metal source salt, a metal source acid, and a metal source hydroxide. In some embodiments of the present invention, the metal source includes one or more of potassium iridium chloride, sodium iridium chloride, iridium trichloride, iridium acetylacetonate, iridic acid, iridium hydroxide, potassium ruthenium chloride, ruthenium trichloride, cobalt nitrate, manganese nitrate, and manganese acetate. In the nitrate solid particles of the present invention, the nitrate includes one or more of sodium nitrate, potassium nitrate, lithium nitrate, calcium nitrate, and magnesium nitrate.

[0011] In the present invention, the metal source solid particles, nitrate solid particles and boric acid solid particles with a molar ratio of 1:(10-1000):(0-100) are first calcined. Specifically, the metal source solid particles, nitrate solid particles and boric acid solid particles with a molar ratio of 1:(10-1000):(0-100) are first mixed by a physical mixing method and then calcined; more specifically, the metal source solid particles, nitrate solid particles and boric acid solid particles with a molar ratio of 1:(10-1000):(0-100) are mixed by grinding and then calcined. Preferably, the metal source solid particles, nitrate solid particles and boric acid solid particles with a molar ratio of 1:(10-1000):(0-100) are mixed by grinding with a mortar or mechanical ball milling and then calcined. In the present invention, the reaction raw materials can react in a molten state through calcination. The calcination temperature in the present invention is 300°C to 600°C, and the calcination time is 0.5 h to 10 h.

[0012] After calcining metal source solid particles, nitrate solid particles and boric acid solid particles with a molar ratio of 1:(10-1000):(0-100), the calcined product is washed. In some embodiments of the present invention, one or more of sulfuric acid, hydrochloric acid, nitric acid, water, and perchloric acid are used for washing. After washing, the washed product is dried to obtain oxide nanosheets. Preferably, the drying is one or more of freeze-vacuum drying, high-temperature vacuum drying, or oven drying.

[0013] The preparation method provided by the present invention mixes reaction materials in a specific molar ratio and uses calcination to make them reach a molten salt state, solving the problem of the preparation of sheet-structured oxide nanosheets with high crystallinity and stable crystal phases that cannot be achieved in the prior art, realizing the preparation of sheet-structured oxide nanosheets with high crystallinity and stable crystal phases, and effectively enhancing the catalytic activity of the material, which is very suitable for application in proton exchange membrane water electrolysis hydrogen production technology.

[0014] The present invention provides oxide nanosheets obtained by the preparation method described in any one of the above. The oxide nanosheets provided by the present invention have good sheet structure characteristics, high crystallinity, and a stable crystal phase. In addition, the oxide nanosheets provided by the present invention modified with boric acid have stronger catalytic activity. In the experiments of the present invention, based on the preparation method provided by the present invention, the sheet morphology characteristics of IrO x -H3BO3 are obvious and have a stable rutile crystal phase, which makes it more advantageous in terms of catalyst stability compared to metastable iridium oxide materials. In addition, the oxide nanosheets provided by the present invention modified with boric acid have higher activity normalized to the electrode area and higher intrinsic activity normalized to the electrochemically active surface area (ECSA) compared to the oxide nanosheets without boric acid modification.

[0015] The present invention provides the application of the oxide nanosheets obtained by the preparation method described in any one of the above as an oxygen evolution catalyst for water electrolysis. The oxide nanosheets of the present invention have the potential for practical application in water electrolysis hydrogen production. Specifically, the present invention also provides a proton exchange membrane water electrolysis hydrogen production device, including a cathode catalyst layer, an anode catalyst layer, and a proton exchange membrane disposed between the cathode catalyst layer and the anode catalyst layer; the catalyst used in the anode catalyst layer is the oxide nanosheets obtained by the preparation method described in any one of the above.

[0016] The present invention provides oxide nanosheets, a preparation method thereof, and applications thereof. The preparation method provided by the present invention mixes reaction materials in a specific molar ratio and calcines them to a molten salt state. The obtained oxide nanosheets have good sheet-like structural characteristics and a stable crystal phase, effectively enhancing the catalytic performance of the material, having the potential for practical application in hydrogen production by water electrolysis, and the catalytic activity can be further enhanced after boric acid modification; in addition, the process is simple and convenient for large-scale preparation. In the experiments of the present invention, based on the preparation method provided by the present invention, the prepared IrO x nanosheets have a rutile crystal phase structure, relatively high crystallinity and a stable crystal phase, and have certain performance in a water electrolysis device; the boric acid-modified IrO x -H3BO3 also has a rutile crystal phase structure, relatively high crystallinity and a stable crystal phase, and has better performance in a water electrolysis device compared to IrO x . The performance of a water electrolysis device using a Nafion115 proton exchange membrane and an IrO x -H3BO3 anode-side catalyst can reach 1.696 V@2 A cm -2 and stably operate for 300 h without performance degradation. Description of the Drawings

[0017] Figure 1 Scanning electron microscope image of the boric acid-modified iridium oxide nanosheet IrO x -H3BO3 prepared in Example 1;

[0018] Figure 2 Scanning electron microscope image of the non-boric acid-modified iridium oxide nanosheet IrO x prepared in Example 2;

[0019] Figure 3 Powder X-ray diffraction pattern of the sample of IrO x -H3BO3 prepared in Example 1 before washing;

[0020] Figure 4 Powder XRD comparison pattern of the finally obtained samples of IrO x -H3BO3 prepared in Example 1 and IrO x prepared in Example 2 after washing;

[0021] Figure 5 Comparison pattern of the activities normalized to the electrode area of the finally obtained samples of IrO x -H3BO3 prepared in Example 1 and IrO x prepared in Example 2;

[0022] Figure 6 For IrO x-H3BO3 and IrO prepared in Example 2 x Comparison chart of the electrochemically active surface area (ECSA) of the final sample;

[0023] Figure 7 IrO prepared in Example 1 x -H3BO3 and IrO prepared in Example 2 x Comparison chart of the polarization curve activity in the water electrolysis device of the final sample;

[0024] Figure 8 IrO prepared in Example 1 x -H3BO3 and IrO prepared in Example 2 x Comparison chart of the stability at a constant current density in the water electrolysis device of the final sample;

[0025] Figure 9 Scanning electron microscope image of boric acid-modified ruthenium oxide RuO-H3BO3 prepared in Example 12 x -H3BO3;

[0026] Figure 10 Scanning electron microscope image of unmodified ruthenium oxide RuO prepared in Example 13 x ;

[0027] Figure 11 RuO prepared in Example 12 x -H3BO3 and RuO prepared in Example 13 x Comparison chart of the activity normalized to the electrode area of the final sample;

[0028] Figure 12 Scanning electron microscope image of boric acid-modified manganese oxide MnO-H3BO3 prepared in Example 14 x -H3BO3;

[0029] Figure 13 Scanning electron microscope image of unmodified manganese oxide MnO prepared in Example 15 x ;

[0030] Figure 14 MnO prepared in Example 14 x -H3BO3 and MnO prepared in Example 15 x Comparison chart of the activity normalized to the electrode area of the final sample;

[0031] Figure 15 Scanning electron microscope image of boric acid-modified cobalt oxide CoO-H3BO3 prepared in Example 16 x -H3BO3;

[0032] Figure 16Cobalt oxide CoO without boric acid modification prepared in Example 17 x Scanning electron microscope image;

[0033] Figure 17 CoO prepared in Example 16 x -H3BO3 and CoO prepared in Example 17 x Comparison chart of the activities of the final samples normalized to the electrode area. Detailed implementation manners

[0034] The present invention discloses oxide nanosheets, a preparation method and an application thereof. Those skilled in the art can draw on the content of this article and appropriately improve process parameters to achieve. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all regarded as included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and those skilled in the art can obviously make changes or appropriate modifications and combinations to the methods and applications in this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0035] The present invention is further described below in conjunction with embodiments:

[0036] Example 1

[0037] Using a mortar and pestle grinding method, 0.26 mmol of solid precursor particles of potassium hexachloroiridate, 23.5 mmol of solid sodium nitrate particles, and 0.26 mmol of solid boric acid particles are uniformly mixed; the obtained mixed solid powder is placed in a crucible, the heating rate is 5 °C / min, and the reaction is carried out at 400 °C for 1 h, and then naturally cooled; it is stirred and washed with 250 mL of 0.5 mol / L sulfuric acid aqueous solution, then filtered by suction, washed three times with water, and the obtained filter cake is freeze-dried under vacuum and the sample is collected.

[0038] Example 2

[0039] Using a mortar and pestle grinding method, 0.26 mmol of solid precursor particles of potassium hexachloroiridate, 23.5 mmol of solid sodium nitrate particles are uniformly mixed; the obtained mixed solid powder is placed in a crucible, the heating rate is 5 °C / min, and the reaction is carried out at 400 °C for 1 h, and then naturally cooled; it is stirred and washed with 250 mL of 0.5 mol / L sulfuric acid aqueous solution, then filtered by suction, washed three times with water, and the obtained filter cake is freeze-dried under vacuum and the sample is collected.

[0040] For IrO prepared in Example 1 x -H3BO3 and IrO prepared in Example 2 x , scanning electron microscope morphology characterization is carried out, and the results are shown in Figure 1 and Figure 2As shown Figure 1 Scanning electron microscope image of the boric acid-modified iridium oxide nanosheets IrO x -H3BO3 prepared in Example 1, Figure 2 Scanning electron microscope image of the unmodified boric acid iridium oxide nanosheets IrO x prepared in Example 2, Figure 1 and Figure 2 The scale bars of both are 1 μm, and the prepared catalysts all have obvious flaky structural characteristics.

[0041] For the sample of IrO x prepared in Example 2 before washing, powder X-ray diffraction characterization was carried out, and the results are shown in Figure 3 as shown Figure 3 Powder X-ray diffraction pattern of the sample of IrO x prepared in Example 2 before washing. The results show that the phase structure of IrO x before washing is already the rutile phase structure, rather than evolved from other structures after washing.

[0042] For the IrO x -H3BO3 prepared in Example 1 and the IrO x prepared in Example 2, powder X-ray diffraction comparative characterization was carried out, and the results are shown in Figure 4 as shown Figure 4 Powder XRD comparative diagram of the final samples of IrO x -H3BO3 prepared in Example 1 and IrO x prepared in Example 2 after washing. As can be seen from Figure 4 both are stable rutile phase structures.

[0043] For the IrO x -H3BO3 prepared in Example 1 and the IrO x prepared in Example 2, three-electrode activity comparative tests were carried out, and the results are shown in Appendix Figure 5 and Figure 6 as shown Figure 5 Comparison diagram of the activities normalized to the electrode area of the final samples of IrO x -H3BO3 prepared in Example 1 and IrO x prepared in Example 2, Figure 6 Comparison diagram of the electrochemically active surface area (ECSA) of the final samples of IrO x -H3BO3 prepared in Example 1 and IrO x prepared in Example 2. As can be seen from Figure 5 and Figure 6 the IrO x -H3BO3 catalyst relative to IrOx The catalyst has higher activity normalized to the electrode area, electrochemically active surface area (ECSA), and intrinsic activity normalized to the ECSA.

[0044] For the IrO x -H3BO3 prepared in Example 1 and the IrO x prepared in Example 2, performance tests were carried out in a water electrolysis device. The comparison results of the polarization curve activity are shown in Figure 7 as follows. Figure 7 Figure x is the comparison graph of the polarization curve activity in the water electrolysis device for the final samples of IrO x -H3BO3 prepared in Example 1 and the IrO Figure 8 prepared in Example 2. The stability results are shown in Figure 8 as follows. x Figure x is the comparison graph of the stability at a constant current density in the water electrolysis device for the final samples of IrO x -H3BO3 and the IrO x prepared in Example 2. The IrO x -H3BO3 catalyst has better water electrolysis activity than the IrO

[0045] Example 3

[0046] Using the mechanical ball milling method, 0.26 mmol of solid precursor particles of sodium iridium chloride, 2.6 mmol of solid potassium nitrate particles, and 0.26 mmol of solid boric acid particles were uniformly mixed; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min. The reaction was carried out at 400 °C for 10 h, and then it was naturally cooled; it was stirred and washed with 250 mL of 0.5 mol / L sulfuric acid aqueous solution, then filtered by suction, washed with water three times, and the obtained filter cake was freeze-dried under vacuum to collect the sample.

[0047] For the oxide nanosheet material prepared in Example 3, scanning electron microscopy characterization, powder X-ray diffraction characterization, three-electrode activity test characterization, and performance test characterization in a water electrolysis device were carried out. The characterization results are similar to the relevant characterization results of Example 1.

[0048] Example 4

[0049] The solid precursor particles of 0.26 mmol iridium(III) chloride, 26 mmol calcium nitrate solid particles, and 2.6 mmol boric acid solid particles were uniformly mixed by grinding with a mortar; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min. The reaction was carried out at 600 °C for 0.5 h, and then it was naturally cooled; it was stirred and washed with 250 mL of 1 mol / L hydrochloric acid aqueous solution, then filtered by suction, washed three times with water, and the obtained filter cake was dried under high temperature and vacuum to collect the sample.

[0050] For the oxide nanosheet material prepared in Example 4, scanning electron microscopy characterization, powder X-ray diffraction characterization, three-electrode activity test characterization, and performance test characterization in a water electrolysis device were carried out. The characterization results were similar to the relevant characterization results of Example 1.

[0051] Example 5

[0052] The solid precursor particles of 0.26 mmol iridium(III) acetylacetonate, 260 mmol magnesium nitrate solid particles, and 26 mmol boric acid solid particles were uniformly mixed by grinding with a mortar; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min. The reaction was carried out at 400 °C for 5 h, and then it was naturally cooled; it was stirred and washed with 250 mL of 1 mol / L nitric acid aqueous solution, then filtered by suction, washed three times with water, and the obtained filter cake was dried in an oven to collect the sample.

[0053] For the oxide nanosheet material prepared in Example 5, scanning electron microscopy characterization, powder X-ray diffraction characterization, three-electrode activity test characterization, and performance test characterization in a water electrolysis device were carried out. The characterization results were similar to the relevant characterization results of Example 1.

[0054] Example 6

[0055] The solid precursor particles of 0.26 mmol chloroiridic acid, 23.5 mmol lithium nitrate solid particles, and 0.026 mmol boric acid solid particles were uniformly mixed by grinding with a mortar; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min. The reaction was carried out at 300 °C for 10 h, and then it was naturally cooled; it was stirred and washed with 250 mL of 1 mol / L perchloric acid aqueous solution, then filtered by suction, washed three times with water, and the obtained filter cake was freeze-dried under vacuum to collect the sample.

[0056] For the oxide nanosheet material prepared in Example 6, scanning electron microscopy characterization, powder X-ray diffraction characterization, three-electrode activity test characterization, and performance test characterization in a water electrolysis device were carried out. The characterization results were similar to the relevant characterization results of Example 1.

[0057] Example 7

[0058] The solid precursor particles of 0.26 mmol iridium hydroxide, 23.5 mmol sodium nitrate solid particles, and 0.26 mmol boric acid solid particles were uniformly mixed by grinding with a mortar; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min. The reaction was carried out at 400 °C for 1 h, and then it was naturally cooled; 250 mL of ultrapure water was used for stirring and washing, and then suction filtration was carried out. It was washed three times with water, and the obtained filter cake was freeze-dried under vacuum to collect the sample.

[0059] For the oxide nanosheet material prepared in Example 7, scanning electron microscopy characterization, powder X-ray diffraction characterization, three-electrode activity test characterization, and performance test characterization in a water electrolysis device were carried out. The characterization results were similar to the relevant characterization results of Example 1.

[0060] Example 8

[0061] The solid precursor particles of 0.26 mmol potassium ruthenium chloride, 23.5 mmol sodium nitrate solid particles, and 0.26 mmol boric acid solid particles were uniformly mixed by grinding with a mortar; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min. The reaction was carried out at 400 °C for 1 h, and then it was naturally cooled; 250 mL of 0.5 mol / L sulfuric acid aqueous solution was used for stirring and washing, and then suction filtration was carried out. It was washed three times with water, and the obtained filter cake was freeze-dried under vacuum to collect the sample.

[0062] For the oxide nanosheet material prepared in Example 8, scanning electron microscopy characterization, powder X-ray diffraction characterization, three-electrode activity test characterization, and performance test characterization in a water electrolysis device were carried out. The characterization results were similar to the relevant characterization results of Example 1.

[0063] Example 9

[0064] The solid precursor particles of 0.26 mmol ruthenium trichloride, 23.5 mmol sodium nitrate solid particles, and 0.26 mmol boric acid solid particles were uniformly mixed by grinding with a mortar; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min. The reaction was carried out at 400 °C for 1 h, and then it was naturally cooled; 250 mL of 0.5 mol / L sulfuric acid aqueous solution was used for stirring and washing, and then suction filtration was carried out. It was washed three times with water, and the obtained filter cake was freeze-dried under vacuum to collect the sample.

[0065] For the oxide nanosheet material prepared in Example 9, scanning electron microscopy characterization, powder X-ray diffraction characterization, three-electrode activity test characterization, and performance test characterization in a water electrolysis device were carried out. The characterization results were similar to the relevant characterization results of Example 1.

[0066] Example 10

[0067] The solid precursor particles of 0.26 mmol cobalt nitrate, 23.5 mmol sodium nitrate solid particles, and 0.26 mmol boric acid solid particles were uniformly mixed by grinding with a mortar; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min. The reaction was carried out at 400 °C for 1 h, and then naturally cooled; it was stirred and washed with 250 mL of 0.5 mol / L sulfuric acid aqueous solution, then filtered by suction, washed with water three times, and the obtained filter cake was freeze-dried under vacuum to collect the sample.

[0068] The oxide nanosheet material prepared in Example 10 was characterized by scanning electron microscopy, powder X-ray diffraction, three-electrode activity test, and performance test in a water electrolysis device. The characterization results were similar to the relevant characterization results of Example 1.

[0069] Example 11

[0070] The solid precursor particles of 0.26 mmol manganese nitrate, 23.5 mmol sodium nitrate solid particles, and 0.26 mmol boric acid solid particles were uniformly mixed by grinding with a mortar; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min. The reaction was carried out at 400 °C for 1 h, and then naturally cooled; it was stirred and washed with 250 mL of 0.5 mol / L sulfuric acid aqueous solution, then filtered by suction, washed with water three times, and the obtained filter cake was freeze-dried under vacuum to collect the sample.

[0071] The oxide nanosheet material prepared in Example 11 was characterized by scanning electron microscopy, powder X-ray diffraction, three-electrode activity test, and performance test in a water electrolysis device. The characterization results were similar to the relevant characterization results of Example 1.

[0072] Example 12

[0073] The solid precursor particles of 0.49 mmol ruthenium trichloride, 23.5 mmol sodium nitrate solid particles, and 0.49 mmol boric acid solid particles were uniformly mixed by grinding with a mortar; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min. The reaction was carried out at 400 °C for 1 h, and then naturally cooled; it was stirred and washed with 250 mL of water, then filtered by suction, washed with water three times, and the obtained filter cake was freeze-dried under vacuum to collect the sample.

[0074] Example 13

[0075] Using a mortar and pestle, 0.49 mmol of solid precursor particles of ruthenium(III) chloride and 23.5 mmol of solid sodium nitrate particles were uniformly mixed; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min. The reaction was carried out at 400 °C for 1 h, and then it was naturally cooled; 250 mL of water was used for stirring and washing, and then suction filtration was carried out. It was washed three times with water, and the obtained filter cake was freeze-dried under vacuum to collect the sample.

[0076] The RuO prepared in Example 12 x -H3BO3 and the RuO prepared in Example 13 x were characterized by scanning electron microscopy (SEM). The results are shown in Figure 9 and 10 as shown. Figure 9 Figure x is the SEM image of the boric acid-modified ruthenium oxide RuO-H3BO3 prepared in Example 12; Figure 10 Figure x is the SEM image of the unmodified ruthenium oxide RuO prepared in Example 13. Figure 9 The scale bars of Figure 10 and

[0077] are both 1 μm. The prepared catalysts all have a flake structure, indicating the feasibility of obtaining a good flake structure after optimizing the preparation parameters. x -H3BO3 and the RuO prepared in Example 13 x were tested for three-electrode activity comparison. The results are shown in Figure 11 as shown. Figure 11 Figure x is the comparison chart of the activities of the final samples of RuO-H3BO3 prepared in Example 12 and RuO prepared in Example 13 normalized to the electrode area. The RuO-H3BO3 catalyst has a higher activity normalized to the electrode area than the RuO catalyst. x x -H3BO3 catalyst has a higher activity normalized to the electrode area compared to the RuO x catalyst.

[0078] Example 14

[0079] Using a mortar and pestle, 0.91 mmol of solid precursor particles of manganese(II) acetate, 23.5 mmol of solid sodium nitrate particles, and 0.91 mmol of solid boric acid particles were uniformly mixed; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min. The reaction was carried out at 400 °C for 1 h, and then it was naturally cooled; 250 mL of water was used for stirring and washing, and then suction filtration was carried out. It was washed three times with water, and the obtained filter cake was freeze-dried under vacuum to collect the sample.

[0080] Example 15 ​

[0081] The solid precursor particles of 0.91 mmol of manganese acetate and 23.5 mmol of sodium nitrate solid particles were uniformly mixed by using a mortar and pestle grinding method; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min, and the reaction was carried out at 400 °C for 1 h, and then naturally cooled; 250 mL of water was used for stirring and washing, and then suction filtration was carried out, and washed with water three times, and the obtained filter cake was freeze-dried under vacuum and the sample was collected.

[0082] For the MnO prepared in Example 14 x -H3BO3 and the MnO prepared in Example 15 x were characterized by scanning electron microscopy, and the results are shown in Figure 12 and Figure 13 as shown. Figure 12 is the scanning electron micrograph of the boric acid-modified manganese oxide MnO x -H3BO3 prepared in Example 14; Figure 13 is the scanning electron micrograph of the manganese oxide MnO x without boric acid modification prepared in Example 15. Figure 12 and Figure 13 both have a scale of 1 μm, and the prepared catalysts all have a flaky structure, indicating the feasibility of obtaining a good flaky structure after optimizing the preparation parameters.

[0083] For the MnO prepared in Example 14 x -H3BO3 and the MnO prepared in Example 15 x a three-electrode activity comparison test was carried out, and the results are shown in Appendix Figure 14 as shown. Figure 14 is the comparison chart of the activities normalized to the electrode area of the final samples of MnO x -H3BO3 prepared in Example 14 and MnO x prepared in Example 15. The MnO x -H3BO3 catalyst has a higher activity normalized to the electrode area than the MnO x catalyst.

[0084] Example 16

[0085] The solid precursor particles of 0.85 mmol of cobalt nitrate, 23.5 mmol of sodium nitrate solid particles and 0.85 mmol of boric acid solid particles were uniformly mixed by using a mortar and pestle grinding method; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min, and the reaction was carried out at 400 °C for 1 h, and then naturally cooled; 250 mL of water was used for stirring and washing, and then suction filtration was carried out, and washed with water three times, and the obtained filter cake was freeze-dried under vacuum and the sample was collected.

[0086] Example 17

[0087] The solid precursor particles of 0.85 mmol cobalt nitrate and 23.5 mmol sodium nitrate solid particles were uniformly mixed by grinding with a mortar; the obtained mixed solid powder was placed in a crucible, and the heating rate was 5 °C / min. The reaction was carried out at 400 °C for 1 h, and then it was naturally cooled; 250 mL of water was used for stirring and washing, and then suction filtration was carried out. After washing three times with water, the obtained filter cake was freeze-dried under vacuum and the sample was collected.

[0088] For the CoO prepared in Example 16 x -H3BO3 and the CoO prepared in Example 17 x were characterized by scanning electron microscopy. The results are shown in Figure 15 and Figure 16 as shown. Figure 15 is the scanning electron microscopy image of the boric acid-modified cobalt oxide CoO x -H3BO3 prepared in Example 16; Figure 16 is the scanning electron microscopy image of the cobalt oxide CoO x without boric acid modification prepared in Example 17. Figure 15 and Figure 16 both have a scale of 1 μm. The prepared catalysts all have a flaky structure, indicating the feasibility of obtaining a good flaky structure after optimizing the preparation parameters.

[0089] For the CoO prepared in Example 16 x -H3BO3 and the CoO prepared in Example 17 x a three-electrode activity comparison test was carried out. The results are shown in Figure 17 as shown. Figure 17 is the comparison chart of the activities of the CoO x -H3BO3 prepared in Example 16 and the CoO x final sample normalized to the electrode area. The CoO x -H3BO3 catalyst has a higher activity normalized to the electrode area than the CoO x catalyst.

[0090] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A method for preparing oxide nanosheets, characterized in that, Comprising the following steps: Calcining solid particles of a metal source, solid particles of a nitrate, and solid particles of boric acid with a molar ratio of 1:(10 - 1000):(0 - 100), and washing the calcined product to obtain oxide nanosheets; The metal source includes one or more of an Ir source, a Ru source, a Co source, and a Mn source.

2. The preparation method according to claim 1, characterized in that, The molar ratio of the solid particles of the metal source, the solid particles of the nitrate, and the solid particles of boric acid is 1:(10 - 1000):(0.1 - 100).

3. The preparation method according to claim 1 or 2, characterized in that, The temperature of the calcination is 300°C - 600°C, and the time of the calcination is 0.5 h - 10 h.

4. The preparation method according to claim 1 or 2, characterized in that, The metal source includes one or more of a metal source salt, a metal source acid, and a metal source hydroxide.

5. The preparation method according to claim 1 or 2, characterized in that, The metal source includes one or more of potassium hexachloroiridate, sodium hexachloroiridate, iridium trichloride, iridium acetylacetonate, chloroiridic acid, iridium hydroxide, potassium ruthenium chloride, ruthenium trichloride, cobalt nitrate, manganese nitrate, and manganese acetate.

6. The preparation method according to claim 1 or 2, characterized in that The nitrate includes one or more of sodium nitrate, potassium nitrate, lithium nitrate, calcium nitrate, and magnesium nitrate.

7. The preparation method according to claim 1 or 2, characterized in that, Mixing solid particles of a metal source, solid particles of a nitrate, and solid particles of boric acid with a molar ratio of 1:(10 - 1000):(0 - 100) by grinding and then performing calcination.

8. Oxide nanosheets obtained by the preparation method according to any one of claims 1 - 7.

9. Application of the oxide nanosheets obtained by the preparation method according to any one of claims 1 - 7 as an oxygen evolution catalyst for water electrolysis.

10. A proton exchange membrane water electrolysis hydrogen production device, characterized in that, Comprising a cathode catalyst layer, an anode catalyst layer, and a proton exchange membrane disposed between the cathode catalyst layer and the anode catalyst layer; the catalyst used in the anode catalyst layer is the oxide nanosheets obtained by the preparation method according to any one of claims 1 - 7.

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