Ultrafast synthesis of nitrides based on Joule heating

Abstract

The present invention discloses a method for ultrafast synthesis of nitrides based on Joule heat, comprising: dissolving an M source and a nitrogen source in a solvent to obtain a precursor prefabricated solution; heating the precursor prefabricated solution to 60-120° C. until the solvent is completely evaporated, followed by drying to obtain a solid precursor; adding the obtained solid precursor to a Joule heat device, rapidly heating the precursor to 600-2000° C. by generating Joule heat through pulse discharge under a protective atmosphere, maintaining the temperature for 0.3-10 seconds, and then cooling the temperature to room temperature, and performing a heating-cooling operation cycle several times to obtain a nitride material (MN x );MN synthesized by the present invention x In the method, M can be metal, non-metal or multi-metal doping and alloy, etc., and the synthesis speed is extremely fast, the operation is simple, the energy consumption is low, and it has a good industrial production foundation and broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of nitride preparation, and in particular to a method for ultrafast synthesis of nitride (MN) based on Joule heat. x ) method. Background Art

[0002] Nitride (MN x ) materials are a class of non-precious metal materials with important application prospects. This material has a wide range of application potential in the fields of energy, energy storage and environment (Advanced science, 2016, 3(5):1500286). x During the formation of MN, the interstitial atoms between the metal M and nitrogen N lead to the expansion of the lattice, thereby increasing the distance between the metal atoms. This structural change leads to the contraction of the metal d-band energy band and the increase of the state density near the Fermi level. This special electronic structure makes MN x It shows adsorption properties similar to those of precious metals (Science, 1973, 181(4099): 547-549; Coordination Chemistry Reviews, 2013, 257(13-14): 1946-1956). It is precisely because of this special electronic structure that MN x The material shows good catalytic activity in the field of hydrogen-related catalytic reactions. For example, in carbon dioxide hydrogenation, hydrodesulfurization, ammonia synthesis and decomposition reactions, MN x The material exhibits catalytic activity comparable to that of precious metals such as platinum and rhodium (Chemical Engineering Journal, 2023, 461: 141981; Molecular Catalysis, 2023, 537: 112930; Catalysis Science & Technology, 2016, 6(20): 7495-7504). x The material is also known as a "quasi-platinum catalyst". In addition to its excellent performance in the field of catalysis, nitrogen can also dissolve in metals to form a solid solution, thus making MN x The materials have a high critical temperature. Therefore, they are expected to be used in the preparation of superconducting devices, especially to replace traditional metal materials in the preparation of superconducting radio frequency resonators. In addition, MN x There are three types of bonds coexisting in the material, namely metallic bonds, ionic bonds and covalent bonds. This also gives them good corrosion resistance and strong adaptability under acidic or alkaline conditions. Therefore, various types of MNs, including single metal, bimetal, multimetal and heterostructures, are widely used. xThese materials have been widely used in electrocatalysis, such as hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) (Green Energy & Environment, 2023, 8(2):406-437; Energy Chem, 2022, 4(2):100072; ACS Catalysis, 2013, 3(6):1184-1194). These materials have shown excellent performance and have attracted extensive research interest in related fields.

[0003] Currently, the synthesis methods of nitrides can be divided into physical methods and chemical methods. Physical methods include magnetron sputtering, laser ablation, arc discharge and pulsed laser deposition (Nanoscale research letters, 2022, 17(1):65; Materials Science in Semiconductor Processing, 2022, 150:106911; Journal of Alloys and Compounds, 2023, 942:169121; Materials Science in Semiconductor Processing, 2022, 150:106911); chemical methods include direct nitridation / ammoniation of transition metal elements and oxides, electrodeposition, hydrothermal synthesis, catalytic molten salt method, etc. (Nanoscale, 2017, 9(45):17722-17730; Materials Science and Engineering: B, 2013, 178(20):1443-1451; Journal of energy Chemistry, 2016, 25(6):967-984; Chem, 2020, 6(9):2382-2394). The common disadvantages of these traditional synthesis methods are long synthesis cycles, high energy consumption, and low yields. In recent years, the method of directly applying electric current to substrate precursors to generate Joule heat (Joule heating method) has successfully prepared metastable nanomaterials such as high entropy alloys, single-atom catalyst materials, uniformly sized all-nanocluster catalysts, and transition metal carbide catalysts (Science, 2018, 359(6383):1489-1494; ACS Catalysis, 2023, 14:183-191; ACS Catalysis, 2023, 13(14):9777-9791; Nature Communications, 2022, 13(1):262). At the same time, CN116855995A also discloses a method for preparing transition metal nitrides, which uses carbon cloth as a carrier, loads transition metal salts onto the carbon cloth, and performs Joule heat shock in an ammonia atmosphere to obtain transition metal nitrides. This method relies on the carbon cloth carrier to obtain a small amount of transition metal nitrides, but cannot obtain a large amount of pure-phase nitride materials. In view of the current problems in nitride synthesis and the characteristics of Joule heating, we have developed a new method for ultrafast synthesis of a large amount of pure-phase nitrides based on Joule heat. The unique heating method of Joule heat is used to achieve controllable synthesis of pure-phase nitrides, reduce the synthesis cycle of pure-phase nitrides to the second level, and achieve ultrafast synthesis of pure-phase microporous structure nitrides. At the same time, the nitride material prepared by the present invention has the advantages of simple operation and extremely low energy consumption. The synthesized MNx M can be a metal, a non-metal, or a multi-metal doping or alloy, etc. In addition, the preparation method provided in this application is simple in process, low in cost, safe and efficient, and has a good industrial production foundation and broad application prospects. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a method for ultrafast synthesis of nitride (MN x The key to this method is to generate Joule heat through pulse discharge, which causes the precursor compound to heat up and cool down rapidly to produce nitride materials.

[0005] The technical solutions of the present invention are as follows:

[0006] A method for ultrafast synthesis of nitrides based on Joule heat, comprising:

[0007] The M source and the nitrogen source are dissolved in a solvent to obtain a precursor pre-solution; the precursor pre-solution is heated to 60-120° C. until the solvent is completely evaporated, and then dried to obtain a solid precursor; the obtained solid precursor is added to a Joule heating device, and the temperature is rapidly raised to 600-2000° C. by pulse discharge to generate Joule heat under a protective atmosphere, maintained for 0.3-10 seconds, and then cooled to room temperature. The heating-cooling operation is repeated several times (preferably 1-10 times) to obtain a nitride material (denoted as: MN x ), the material has a very good crystal structure and a certain pore structure distribution;

[0008] in,

[0009] M in the M source is selected from one or more elements of Si, Ta, Ti, V, B, C, Fe, Co, and Ga. The M source can be in the form of nitrate, sulfate, chloride, oxide, metal metasalt, metal inorganic salt, etc.; preferably, the M source is one or more of boric acid, TiCl4, ammonium metavanadate, and gallium nitrate;

[0010] The nitrogen source is selected from one or more of urea, melamine, biuret, dicyandiamide, thiourea, and hexamethylenetetramine;

[0011] The solvent is selected from one or more of deionized water, anhydrous methanol, ethylene glycol, acetone, DMF, chloroform, toluene, and anhydrous ethanol;

[0012] The preferred mass ratio of the M source to the nitrogen source is 1:1 to 5;

[0013] The protective atmosphere can be N2, H2, CO2, NH3, NH3 / Ar, CO2 / Ar, H2 / Ar, etc.

[0014] The current of the pulse discharge is 100 to 500 amperes, and the maximum temperature generated by Joule heat is 600 to 2000°C; the single discharge time of the pulse discharge is 0.5 to 10 seconds; the number of pulse discharges is 1 to 10 times; and the power supply used for the pulse discharge is a DC power supply or an AC power supply.

[0015] The design principles of the present invention are as follows:

[0016] Traditional heating methods are mainly carried out through thermal radiation, heat transfer and heat convection, which will lead to: 1) a relatively slow material heating rate; 2) uneven temperature distribution. This will lead to a long material synthesis cycle, serious heat waste and high energy consumption. Joule heating is to directly heat the material through electrodes to provide energy, which can reach the preset temperature within milliseconds. At the same time, the material is heated relatively uniformly, and there are no hot spots and other problems. It is a more cutting-edge method among the current synthesis methods. The present invention takes advantage of the advantages of Joule heating and combines it with the characteristics of nitride synthesis to successfully synthesize different types of nitride materials, which has great advantages in both energy consumption and time-space yield.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] This invention uses nitrogen-containing organic compounds as nitrogen sources, with the M source selected from one or more of nitrates, sulfates, chlorides, oxides, metal metasalts, and inorganic metal salts, to prepare nitride materials using ultrafast heating equipment. Compared to traditional nitride synthesis, which takes more than a dozen hours, this invention utilizes ultrafast heating technology to produce nitride materials in milliseconds. The synthesized nitride materials have a very good crystal structure and a well-defined pore structure distribution.

[0019] The nitride material prepared by the present invention has a regular morphology and structure, and the preparation process is simple, the synthesis is fast, the cost is low, it is safe and efficient, and the atomic utilization rate is high. It can be directly generated by in-situ reaction of raw materials and has great prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 : X-ray powder diffraction (XRD) analysis results of the nitrides BN, VN, GaN, and TiN prepared in the examples; (a) BN; (b) VN; (c) GaN; (d) TiN.

[0021] Figure 2 : Fourier transform infrared spectroscopy (FTIR) results of the nitrides BN, VN, GaN, and TiN prepared in the examples; (a) BN; (b) VN; (c) GaN; (d) TiN.

[0022] Figure 3: Scanning electron microscope (SEM) analysis results of the nitrides BN, VN, GaN, and TiN prepared in the examples; (ac) BN; (df) GaN; (gi) TiN; (jl) VN.

[0023] Figure 4 : Transmission electron microscopy (TEM) analysis results of the nitrides BN, VN, GaN, and TiN prepared in the examples; (ac) BN; (df) GaN; (gi) TiN; (jl) VN.

[0024] Figure 5 : Schematic diagram of Joule heat synthesis of nitride materials, and comparison of energy consumption with conventional synthesis methods. DETAILED DESCRIPTION

[0025] The present invention is further described below by means of specific examples, but the protection scope of the present invention is not limited thereto.

[0026] Joule heating equipment used in the following examples: Model: JH-3.3-P, Hefei In-Situ Technology Co., Ltd.

[0027] Example 1

[0028] This embodiment provides a novel method for ultrafast synthesis of BN based on Joule heat, comprising the following steps: dissolving 5.183 g of boric acid and 19.018 g of urea in 180 mL of anhydrous methanol to prepare a precursor pre-solution;

[0029] The precursor pre-solution was heated to 90° C. in a water bath until the solvent was completely evaporated;

[0030] The residue after complete evaporation of the solvent was transferred to a hot air drying oven at 60°C for drying for 24 hours to obtain a solid precursor;

[0031] The obtained solid precursor was added to the Joule heating graphite groove of the Joule heating device, the pulse discharge current was set to 400 amperes, and the temperature was rapidly raised to 1300°C under a nitrogen atmosphere, maintained for 0.8 seconds, and then cooled to room temperature. The rapid heating-cooling cycle process was repeated 7 times to obtain the BN material.

[0032] The BN material has a very good crystal structure and a certain pore structure distribution. Compared with the traditional BN synthesis which takes more than ten hours, the present invention uses ultra-fast heating technology to obtain BN material in seconds. The synthesized BN material has a higher specific surface area (>1000m 2 / g) and smaller pore sizes;

[0033] Figure 1 The diffraction peaks in (a) all correspond to the diffraction peaks of pure BN. Figure 2(a) shows that the characteristic absorption peaks of BN's Fourier transform infrared correspond to the characteristic absorption peaks of commercial BN. Figure 3 (ac) and Figure 4 Middle (ac) show the microstructure of BN.

[0034] Example 2

[0035] Prepare a precursor solution by dissolving 10 ml of TiCl4 and 20.367 g of thiourea in 90 ml of a solvent consisting of anhydrous ethanol and deionized water in a volume ratio of 1:1.

[0036] The precursor pre-solution was heated in a water bath to 75° C. until the solvent was completely evaporated;

[0037] The residue after complete evaporation of the solvent was transferred to a vacuum drying oven at 60°C for drying to obtain a solid precursor;

[0038] The obtained solid precursor was added to the Joule heating graphite groove of the Joule heating device, the pulse discharge current was set to 450 amperes, and the temperature was rapidly raised to 1800°C under a nitrogen atmosphere, maintained for 9 seconds, and then cooled to room temperature. The rapid heating-cooling cycle process was repeated 9 times to obtain TiN material.

[0039] Figure 1 The diffraction peaks in (d) all correspond to the diffraction peaks of pure TiN. Figure 2 (d) shows that the characteristic absorption peaks of TiN by Fourier transform infrared correspond to the characteristic absorption peaks of commercial TiN. Figure 3 Chinese (gi) and Figure 4 The middle (gi) shows the microstructural morphology of TiN.

[0040] Example 3

[0041] A precursor pre-solution was prepared by dissolving 8.653 g of ammonium metavanadate and 18.365 g of dicyandiamide in 200 ml of a solvent consisting of anhydrous methanol and deionized water in a volume ratio of 2:1.

[0042] The precursor pre-solution was heated in a water bath to 60° C. until the solvent was completely evaporated;

[0043] The residue after complete evaporation of the solvent is transferred to a hot air drying oven for drying to obtain a solid precursor;

[0044] The obtained solid precursor was added to the Joule heating graphite groove of the Joule heating device, the pulse discharge current was set to 430 amperes, and the temperature was rapidly raised to 1200°C under a nitrogen atmosphere, maintained for 0.8 seconds, and then cooled to room temperature. The rapid heating-cooling cycle process was repeated 9 times to obtain the VN material.

[0045] Figure 1 The diffraction peaks in (b) all correspond to the VN diffraction peaks of the pure phase. Figure 2 (b) shows that the characteristic absorption peaks of VN's Fourier transform infrared correspond one to one with the characteristic absorption peaks of commercial VN. Figure 3 Chinese (jl) and Figure 4 Middle (jl) shows the microstructural morphology of VN.

[0046] Example 4

[0047] Prepare a precursor solution by dissolving 24.387 g of hexamethylenetetramine and 5.396 g of gallium nitrate in 100 ml of deionized water;

[0048] The precursor pre-solution was heated in an oil bath to 105° C. until the solvent was completely evaporated;

[0049] The residue after complete evaporation of the solvent is transferred to a hot air drying oven for drying to obtain a solid precursor;

[0050] The obtained solid precursor was added to the Joule heating graphite groove of the Joule heating device, the pulse discharge current was set to 400 amperes, and the temperature was rapidly raised to 1100°C under a nitrogen atmosphere, maintained for 0.3 seconds, and then cooled to room temperature. The rapid heating-cooling cycle process was repeated three times to obtain GaN material.

[0051] Figure 1 The diffraction peaks in (c) all correspond to the diffraction peaks of pure GaN. Figure 2 (c) shows that the characteristic absorption peaks of GaN's Fourier transform infrared spectroscopy correspond one to one with the characteristic absorption peaks of commercial GaN. Figure 3 (df) and Figure 4 Middle (d-f) show the microstructural morphology of GaN.

[0052] Table 1 Synthesis conditions and space-time yields of different nitride materials (groove size 0.65cm*2cm*3cm)

[0053]

Claims

1. A method for ultrafast synthesis of nitrides based on Joule heat, characterized in that: The method comprises: The M source and the nitrogen source are dissolved in a solvent to obtain a precursor pre-solution; the precursor pre-solution is heated to 60-120° C. until the solvent is completely evaporated, and then dried to obtain a solid precursor; the obtained solid precursor is added to a Joule heating device, and the temperature is rapidly raised to 600-2000° C. by generating Joule heat through pulse discharge under a protective atmosphere, maintained for 0.3-10 seconds, and then cooled to room temperature, and the heating-cooling operation is repeated several times to obtain a nitride material; in, M in the M source is selected from one or more elements of Si, Ta, Ti, V, B, C, Fe, Co, and Ga; The nitrogen source is selected from one or more of urea, melamine, biuret, dicyandiamide, thiourea and hexamethylenetetramine.

2. The method for ultrafast synthesis of nitrides based on Joule heat according to claim 1, wherein: The M source is in the form of nitrates, sulfates, chlorides, oxides, or metal metasalts.

3. The method for ultrafast synthesis of nitrides based on Joule heat according to claim 1, wherein: The M source is one or more of boric acid, TiCl4, ammonium metavanadate, and gallium nitrate.

4. The method for ultrafast synthesis of nitrides based on Joule heat according to claim 1, wherein: The solvent is selected from one or more of deionized water, anhydrous methanol, ethylene glycol, acetone, DMF, chloroform, toluene, and anhydrous ethanol.

5. The method for ultrafast synthesis of nitrides based on Joule heat according to claim 1, wherein: The mass ratio of the M source to the nitrogen source is 1:1-5.

6. The method for ultrafast synthesis of nitrides based on Joule heat according to claim 1, wherein: The protective atmosphere is N2, H2, CO2, NH3, NH3 / Ar, CO2 / Ar or H2 / Ar.

7. The method for ultrafast synthesis of nitrides based on Joule heat according to claim 1, wherein: The heating-cooling operation cycle is repeated 1 to 10 times.

8. The method for ultrafast synthesis of nitrides based on Joule heat according to claim 1, wherein: The current of the pulse discharge is 100 to 500 amperes, and the maximum temperature generated by Joule heat is 600 to 2000°C; the single discharge time of the pulse discharge is 0.5 to 10 seconds; the number of pulse discharges is 1 to 10 times; and the power supply used for the pulse discharge is a DC power supply or an AC power supply.

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