Monatomic and nanoparticle composite material, and preparation method and application thereof

Abstract

This invention belongs to the field of catalyst preparation technology and new energy development. Specifically, it discloses a single-atom and nanoparticle composite material, its preparation method, and its application. This invention obtains a metal single-atom and nanoparticle composite catalyst through a thermal reduction method. The catalyst is coated onto a conductive substrate and used as the working electrode, with a graphite plate as the counter electrode, and Ag / AgNO₃ as the catalyst. 3 The electrode serves as a reference electrode, and the liquid ammonia solution containing dissolved ammonium salts is used as the electrolyte. Electrocatalytic decomposition of liquid ammonia to produce hydrogen occurs within a high-voltage electrolytic cell. Compared to existing technologies, the method proposed in this invention effectively solves the problem of platinum anodic oxidation dissolution in room-temperature liquid ammonia electrolysis systems. Simultaneously, it develops a novel catalyst for electrocatalytic liquid ammonia decomposition to produce hydrogen, which exhibits exceptionally long stability in strongly acidic liquid ammonia solutions.

Description

A single-atom and nanoparticle composite material, its preparation method and application Technical Field

[0001] This invention relates to the field of catalyst preparation technology and new energy development, and in particular to a single-atom and nanoparticle composite material, its preparation method and application. Background Technology

[0002] Hydrogen is an ideal environmentally friendly energy carrier and is now widely considered a crucial bridge for converting energy from fossil fuels to renewable energy, achieving sustainable energy supply and recycling. However, to realize the large-scale application of hydrogen, the issues of its "green," safe, and efficient preparation, storage, and transportation must first be addressed. Ammonia (NH3) has a high hydrogen storage capacity (17.6 wt%) and can be used as a potential hydrogen storage / production material, and is easily liquefied (~10 bar or -33.35℃) for transportation. More importantly, the decomposition products of ammonia are only hydrogen and harmless nitrogen, with no carbon emissions. Furthermore, NH3 has a low freezing temperature (-77.7℃), making it usable even under extreme conditions. Researchers have conducted extensive studies on the decomposition of NH3 to produce hydrogen, primarily based on the thermal catalytic decomposition of ammonia under high-temperature conditions. This method is energy-intensive and produces large amounts of greenhouse gases such as carbon dioxide. In contrast, the electrocatalytic liquid ammonia decomposition method driven by renewable energy has low energy consumption, a simple reaction device, and a controllable reaction, showing great promise. In the electrocatalytic liquid ammonia decomposition system, the effective use of the catalyst can…

[0003] It significantly improves the reaction kinetics of liquid ammonia decomposition and accelerates the hydrogen production rate.

[0004] Currently, platinum is commonly used as the anode in room-temperature liquid ammonia electrolysis systems, which faces the problem of corrosion and dissolution. Meanwhile, research on catalytic materials for liquid ammonia decomposition is limited, and the activity and stability of existing reported catalytic materials need improvement. Therefore, optimizing the reaction system and developing novel, efficient, and low-cost room-temperature liquid ammonia decomposition catalysts are of great significance. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a single-atom and nanoparticle composite material, its preparation method, and its application.

[0006] To achieve the above objectives, the present invention is implemented according to the following technical solution:

[0007] The first objective of this invention is to provide a method for preparing a composite material of single atoms and nanoparticles, comprising the following steps:

[0008] S1. Melamine C3H6N6 was placed in air and heat-treated at 550°C for 2 hours to obtain carbon nitride nanosheets.

[0009] S2. Disperse 2.35g of carbon nitride nanosheets in 15ml of aqueous solution and stir until homogeneous to obtain solution A;

[0010] S3. Take 3 mg of one of the following: ruthenium trichloride RuCl3·xH2O, rhodium chloride RhCl3, or iridium chloride IrCl3·3H2O, add it to solution A, and stir until homogeneous to obtain solution B;

[0011] S4. Take glucosamine hydrochloride C6H at a mass ratio of 500:3 to 200:3. 13 The metal salts in NO5·HCl and S3, and glucosamine hydrochloride C6H 13 NO5·HCl was added to solution B and stirred until homogeneous to obtain solution C;

[0012] S5. Solution C is rapidly frozen using liquid nitrogen to obtain a solid;

[0013] S6. Place the solid obtained in step S5 into a freeze dryer for freeze drying, and grind it after drying to obtain the sample;

[0014] S7. The sample was placed at 750-850℃ and heat-treated in an inert gas atmosphere for 6 hours to obtain SAs-NPs composite material.

[0015] Preferably, the inert gas in step S7 is argon or nitrogen.

[0016] A second objective of this invention is to provide a single-atom and nanoparticle composite material prepared using the above method.

[0017] The third objective of this invention is to provide an application of single-atom and nanoparticle composite materials as catalysts for hydrogen production by electrolysis of ammonium salt solutions at room temperature. Specifically, SAs-NPs composite materials are coated on a conductive substrate as the cathode, methanol with Ag / AgNO3 is used as the reference electrode, a corrosion-resistant and oxidation-resistant conductive current collector is used as the anode, and ammonium salt is used as the electrolyte to carry out liquid ammonia electrolysis in a high-voltage electrolytic cell.

[0018] Preferably, the conductive substrate is one of glass carbon sheet, graphite plate, and titanium sheet.

[0019] Preferably, the corrosion-resistant, oxidation-resistant, and conductive current collector is a graphite plate.

[0020] Preferably, the solute in the methanol reference electrode of the Ag / AgNO3 is 1 mM AgNO3 and 0.1 M tetrabutylammonium perchlorate.

[0021] Preferably, the ammonium salt is one of ammonium nitrate, ammonium chloride, ammonium fluoride, ammonium bromide, ammonium iodide, and ammonium hexafluorophosphate.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The method for preparing SAs-NPs composite materials provided in the embodiments of the present invention has the advantages of simple operation and the ability to prepare SAs-NPs composite materials of various metals. In addition, the SAs-NPs composite catalyst obtained in the embodiments of the present invention can construct a large number of active sites, which significantly improves the activity of the catalyst.

[0024] (2) The room temperature liquid ammonia electrolysis system was optimized and improved, which solved the problem of anode platinum corrosion and dissolution. The synthesized SAs-NPs composite material was used in the room temperature liquid ammonia electrolysis hydrogen production process, which can achieve effective ammonia decomposition reaction. After decomposition, the molar ratio of hydrogen to nitrogen is close to 3:1. At the same time, the material showed a stability of 200 hours, which is far higher than the performance of the room temperature liquid ammonia decomposition catalysts reported so far. Attached Figure Description

[0025] Figure 1 is a ring dark-field scanning transmission electron microscope image of the Ru-SAs-NPs-800 composite material prepared in Example 1 with spherical aberration correction.

[0026] Figure 2 is a ring dark-field scanning transmission electron microscope image of the Rh-SAs-NPs-800 composite material prepared in Example 2 with spherical aberration correction.

[0027] Figure 3 is a ring dark-field scanning transmission electron microscope image of the Ir-SAs-NPs-800 composite material prepared in Example 3 with spherical aberration correction.

[0028] Figure 4 shows the linear voltammetric scan curves of the Ru-SAs-NPs-800 composite materials prepared in Example 1 and Comparative Example 1 in a liquid ammonia electrolyte containing ammonium salts at room temperature.

[0029] Figure 5 shows the linear voltammetric scan curve of the anode current obtained from the graphite plate test in Example 2.

[0030] Figure 6 shows the linear voltammetric scan curve of the anode current obtained from the platinum sheet test in Comparative Example 2;

[0031] Figure 7 shows the gas chromatography test curves of the Ru-SAs-NPs-800 composite material prepared in Example 1 before and after electrolysis.

[0032] Figure 8 shows the trend of the molar ratio of hydrogen (H2) to nitrogen (N2) in the electrolysis products of the Ru-SAs-NPs-800 composite material prepared in Example 1.

[0033] Figure 9 shows the Ru-SAs-NPs-800 composite material prepared in Example 1 at 10 mA cm⁻¹. -2 Potential-time curves at current densities. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0035] Example 1

[0036] S1. Place 10g of C3H6N6 in air and heat-treat it at 550℃ for 2 hours to obtain carbon nitride nanosheets.

[0037] S2. Disperse 2.35g of carbon nitride nanosheets in 15ml of aqueous solution and stir for 1 hour to obtain solution A;

[0038] S3. Add 0.3 mL of 10 mg / mL RuCl3·xH2O solution to solution A and stir to obtain solution B;

[0039] S4. Take 200 mg of glucosamine hydrochloride C6H 13 NO5·HCl was added to solution B and stirred for 1 hour to obtain solution C;

[0040] S5. Solution C is rapidly frozen using liquid nitrogen to obtain a solid;

[0041] S6. Place the solid in a freeze dryer for freeze drying, and grind it after drying to obtain the sample;

[0042] S7. The sample was placed in an argon atmosphere furnace for heat treatment at 800℃ for 6 hours to obtain the Ru-SAs-NPs-800 composite material.

[0043] Example 2

[0044] S1. Place 10g of C3H6N6 in air and heat-treat it at 550℃ for 2 hours to obtain carbon nitride nanosheets.

[0045] S2. Disperse 2.35g of carbon nitride nanosheets in 15ml of aqueous solution and stir for 1 hour to obtain solution A;

[0046] S3. Add 0.3 mL of 10 mg / mL RhCl3 solution to solution A and stir to obtain solution B;

[0047] S4. Take 200 mg of glucosamine hydrochloride C6H 13 NO5·HCl was added to solution B and stirred for 1 hour to obtain solution C;

[0048] S5. Solution C is rapidly frozen using liquid nitrogen to obtain a solid;

[0049] S6. Place the solid in a freeze dryer for freeze drying, and grind it after drying to obtain the sample;

[0050] S7. The sample was placed in an argon atmosphere furnace for heat treatment at 800℃ for 6 hours to obtain the Rh-SAs-NPs-800 composite material.

[0051] Example 3

[0052] S1. Place 10g of C3H6N6 in air and heat-treat it at 550℃ for 2 hours to obtain carbon nitride nanosheets.

[0053] S2. Disperse 2.35g of carbon nitride nanosheets in 15ml of aqueous solution and stir for 1 hour to obtain solution A;

[0054] S3. Add 0.3 mL of 10 mg / mL IrCl3·3H2O solution to solution A and stir to obtain solution B;

[0055] S4. Take 200 mg of glucosamine hydrochloride C6H 13 NO5·HCl was added to solution B and stirred for 1 hour to obtain solution C;

[0056] S5. Solution C is rapidly frozen using liquid nitrogen to obtain a solid;

[0057] S6. Place the solid in a freeze dryer for freeze drying, and grind it after drying to obtain the sample;

[0058] S7. The sample was placed in an argon atmosphere furnace for heat treatment at 800℃ for 6 hours to obtain the Ir-SAs-NPs-800 composite material.

[0059] Figure 1 shows an annular dark-field scanning transmission electron microscope (TEM) image of the Ru-SAs-NPs-800 composite material prepared in Example 1 with spherical aberration correction; Figure 2 shows an annular dark-field scanning transmission electron microscope (TEM) image of the Rh-SAs-NPs-800 composite material prepared in Example 2 with spherical aberration correction; Figure 3 shows an annular dark-field scanning transmission electron microscope (TEM) image of the Ir-SAs-NPs-800 composite material prepared in Example 3 with spherical aberration correction. As can be seen from Figures 1-3, the synthesis method provided by this invention can prepare composite materials of single atoms and nanoparticles.

[0060] Furthermore, to verify whether the single-atom and nanoparticle composite materials prepared in the above embodiments can be used as catalysts for hydrogen production by electrolysis of ammonium salt solutions at room temperature, and to evaluate their effectiveness in hydrogen production by electrolysis of ammonium salt solutions, tests were conducted through the following application examples.

[0061] Application Example 1

[0062] The Ru-SAs-NPs-800 catalyst prepared in Example 1 was dispersed in an ethanol solution, and a Nafion binder solution was added. The dispersion was then ultrasonically dispersed until homogeneous. This dispersion was dropwise added to a glassy carbon electrode as the working electrode. Ag / AgNO3 (methanol-filled solution) and a graphite plate were used as the reference and counter electrodes, respectively. A liquid ammonia solution of NH4PF6 was used as the electrolyte. Electrolysis was performed within a voltage range of -0.3 to -1.4 V vs. Ag / AgNO3 to achieve the hydrogen production process from the decomposition of liquid ammonia. The mass (mg) to volume (μL) ratio of the Ru-SAs-NPs-800 composite material to the Nafion solution was 1:10, and the molar concentration of the NH4PF6 liquid ammonia solution was 1 M. The hydrogen produced by the decomposition of liquid ammonia was detected by a gas chromatograph with a TCD detector. Specifically, the gas produced after liquid ammonia electrolysis was aspirated with a chromatographic sampling needle and injected into the chromatographic injection port for qualitative and quantitative analysis.

[0063] Application Example 2

[0064] The Ru-SAs-NPs-800 composite material prepared in Example 1 was dispersed in an ethanol solution, and a Nafion binder solution was added. The mixture was then ultrasonically dispersed until homogeneous. This dispersion was dropwise added to a glassy carbon electrode as the counter electrode, with Ag / AgNO3 (methanol-filled solution) as the reference electrode and a graphite plate as the working electrode. A liquid ammonia solution of NH4PF6 was used as the electrolyte. Linear voltammetry was performed within a voltage range of 0–1.0 V vs. Ag / AgNO3. The mass (mg) to volume (μL) ratio of the Ru-SAs-NPs-800 composite material to the Nafion solution was 1:10, and the molar concentration of the NH4PF6 liquid ammonia solution was 1 M.

[0065] Comparative Example 1

[0066] A glassy carbon electrode was used as the working electrode, Ag / AgNO3 (methanol-filled solution) as the reference electrode, a graphite plate as the counter electrode, and a liquid ammonia solution of NH4PF6 as the electrolyte. A linear sweep voltammetric test was performed in the voltage range of -0.3 to -1.4 V vs. Ag / AgNO3. The molar concentration of the liquid ammonia solution of NH4PF6 was 1 M.

[0067] Comparative Example 2

[0068] The Ru-SAs-NPs-800 composite material prepared in Example 1 was dispersed in an ethanol solution, and a Nafion binder solution was added. The mixture was then ultrasonically dispersed until homogeneous. This dispersion was dropwise added to a glassy carbon electrode as the counter electrode, with Ag / AgNO3 (methanol-filled solution) as the reference electrode and a platinum sheet as the working electrode. A liquid ammonia solution of NH4PF6 was used as the electrolyte. Linear voltammetry was performed within the voltage range of 0–1.0 V vs. Ag / AgNO3. The mass (mg) to volume (μL) ratio of the Ru-SAs-NPs-800 composite material to the Nafion solution was 1:10, and the molar concentration of the NH4PF6 liquid ammonia solution was 1 M.

[0069] Referring to Figure 4, which shows the potential-current curves of hydrogen production by liquid ammonia electrolysis in Example 1 and Comparative Example 1 at room temperature, it demonstrates that the Ru-SAs-NPs-800 composite material has good liquid ammonia decomposition activity.

[0070] Referring to Figures 5 and 6, Figure 5 shows the linear voltammetric scan curve for Application Example 1 using a graphite plate as the anode, where the current density remained relatively stable after three cycles. Figure 6 shows the linear voltammetric scan curve for Comparative Example 2 using a platinum sheet as the anode, where the current density was higher in the first cycle and significantly decreased in the second cycle. This demonstrates the good stability of the graphite plate anode.

[0071] Referring to Figures 7-8, Figure 7 shows the gas composition detected by gas chromatography before and after electrolysis in Example 1. The results show that no signal was detected by gas chromatography before electrolysis, while hydrogen and nitrogen signals were detected by gas chromatography after electrolysis. Figure 8 shows that the molar ratio of hydrogen to nitrogen after electrolysis is close to 3:1, indicating that the Ru-SAs-NPs-800 composite material prepared in Example 1 can achieve efficient liquid ammonia decomposition.

[0072] Furthermore, referring to Figure 9, the Ru-SAs-NPs-800 composite material prepared in Example 1 was tested at room temperature in a liquid ammonia electrolyte containing 1M NH4PF6 at 10mA cm⁻¹. -2 Electrolysis curves at current density; the potential remained stable over 200 hours, indicating that the catalyst has excellent stability.

[0073] As can be seen from the above application examples, the SAs-NPs composite material prepared by this invention can construct a large number of active sites when used as a catalyst for hydrogen production from room temperature liquid ammonia solution. This significantly improves the activity of the catalyst. The room temperature liquid ammonia electrolysis system has been optimized and improved, solving the problem of platinum corrosion and dissolution at the anode. The synthesized SAs-NPs composite material can achieve effective ammonia decomposition reaction when used in the room temperature liquid ammonia electrolysis hydrogen production process. After decomposition, the molar ratio of hydrogen to nitrogen is close to 3:1. At the same time, the material exhibits a stability of 200 hours, which is far superior to the performance of currently reported room temperature liquid ammonia decomposition catalysts.

[0074] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a composite material of single atoms and nanoparticles, characterized in that, Includes the following steps: S1. Melamine C3H6N6 was heat-treated in air at 550℃ for 2 hours to obtain carbon nitride nanosheets; S2. 2.35g of carbon nitride nanosheets were dispersed in 15ml of aqueous solution and stirred evenly to obtain solution A; S3. One of ruthenium trichloride RuCl3·xH2O, rhodium chloride RhCl3, and iridium chloride IrCl3·3H2O was added to solution A and stirred evenly to obtain solution B; S4. Glucosamine hydrochloride C6H6N6 was taken at a mass ratio of 500:3 ~ 200:

3. 13 The metal salts in NO5·HCl and S3, and glucosamine hydrochloride C6H 13 After mixing NO5·HCl and solution B, stir evenly to obtain solution C; S5, rapidly freeze solution C using liquid nitrogen to obtain a solid; S6, place the solid obtained in step S5 into a freeze dryer for freeze drying, and grind it after drying to obtain a sample; S7, place the sample at 750~850℃ and heat treat it in an inert gas atmosphere for 6 hours to obtain SAs-NPs composite material.

2. The method for preparing the single-atom and nanoparticle composite material according to claim 1, characterized in that: The inert gas in step S7 is argon or nitrogen.

3. The application of a single-atom and nanoparticle composite material prepared by the method as described in claim 1 or 2 in room temperature electrolytic hydrogen production from a liquid ammonia solution containing ammonium salt.

4. The application of the single-atom and nanoparticle composite material according to claim 3 as a catalyst for hydrogen production by electrolysis of ammonium salt solution at room temperature, characterized in that, SAs-NPs composite material was coated on a conductive substrate as the cathode, methanol with Ag / AgNO3 was used as the reference electrode, a corrosion-resistant and oxidation-resistant conductive current collector was used as the anode, and ammonium salt was used as the electrolyte to carry out liquid ammonia electrolysis in a high-voltage electrolytic cell.

5. The application according to claim 4, characterized in that: The conductive substrate is one of glass carbon sheet, graphite plate, and titanium sheet.

6. The application according to claim 4, characterized in that: The corrosion-resistant, oxidation-resistant, and conductive current collector is a graphite plate.

7. The application according to claim 4, characterized in that: The solutes in the methanol reference electrode of the Ag / AgNO3 are 1 mM AgNO3 and 0.1 M tetrabutylammonium perchlorate.

8. The application according to claim 4, characterized in that: The ammonium salt is one of ammonium nitrate, ammonium chloride, ammonium fluoride, ammonium bromide, ammonium iodide, and ammonium hexafluorophosphate.

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