A method for rapid catalytic preparation of one-dimensional nanocarbide

Abstract

This invention provides a rapid catalytic preparation method for one-dimensional nano-carbide. Under the action of a catalyst, the reactants and carbon materials rapidly heat up through Joule heating under the influence of an electric current, producing gaseous reactants. These gaseous reactants then follow a gas-liquid-solid reaction mechanism to generate one-dimensional nano-carbide. This method features short reaction time, low energy consumption, high product purity, and controllable uniform size, offering significant advantages for industrial applications.

Description

Technical Field

[0001] This invention belongs to the field of one-dimensional nanomaterials technology, specifically relating to a method for preparing one-dimensional carbide nanomaterials based on Joule heating rapid catalysis. Background Technology

[0002] One-dimensional nanomaterials include nanowires, nanorods, nanotubes, and nanoribbons. Unlike bulk materials, they possess unique optical, electrical, magnetic, and electrochemical properties, and are widely used in energy and functional composite materials, electronic devices, and lightweight armor. For example, carbide nanowires such as silicon carbide and boron carbide possess high chemical inertness, high thermal conductivity, ultra-high hardness, and excellent wear resistance, making them promising for applications in extreme environments.

[0003] Methods for synthesizing one-dimensional nanomaterials can be broadly classified into solution growth and vapor-phase growth. Vapor-phase growth mainly includes carbothermal reactions, precursor thermal decomposition, and chemical vapor deposition. Carbothermal reduction methods prepare carbide nanowires in a closed environment at high temperatures. However, limited by reaction temperature and precursor activity, the resulting one-dimensional nanomaterials are often uneven in size and short in length. Since Wagner's pioneering work, the well-known gas-liquid-solid growth mechanism has been extensively studied. In this method, gaseous reactants dissolve in a liquid metal catalyst. Once the catalyst is supersaturated, the product precipitates and grows at the solid-liquid interface. The diameter of the one-dimensional nanomaterials synthesized using this method is determined by the diameter of the catalyst particles, making it an effective way to obtain uniformly sized nanomaterials. However, currently reported vapor-phase growth methods all rely on long-term operation of high-temperature furnaces to generate gaseous reactants, resulting in high energy consumption. For example, in the preparation of carbide nanowires, due to the high melting point and chemical inertness of carbides, it is often necessary to pyrolyze the reaction precursor at temperatures above 1000 degrees Celsius for several hours or even tens of hours, a process that consumes a large amount of energy and time.

[0004] Therefore, developing a low-energy-consumption, low-cost, rapid-reaction, and high-purity method for preparing one-dimensional nanocarbides is of great significance for their large-scale production and application, as well as for energy conservation and emission reduction. Summary of the Invention

[0005] To address the aforementioned problems, this invention, based on the phenomenon of Joule heating generated by the reactants themselves under electric current, provides a method for rapidly heating to over 1000°C to catalytically prepare one-dimensional nanocarbide nanoparticles. This method can prepare uniformly sized one-dimensional nanocarbide nanoparticles within tens of seconds, yielding products with high purity and quality. The preparation time is reduced from over two hours in traditional methods to tens of seconds. The process is simple, easier to control and operate, safe, and environmentally friendly, showing promising application prospects.

[0006] The purpose of this invention is to provide a rapid catalytic preparation method for one-dimensional nano-carbide nanoparticles. In this method, reactants and carbon materials react under heating conditions, with the gaseous reactants reacting in the presence of a catalyst to obtain one-dimensional nanomaterials. The reactants and carbon materials generate Joule heat and rapidly heat up under the influence of an electric current, producing gaseous reactants. These gaseous molecules, under the action of a catalyst, follow a gas-liquid-solid reaction mechanism to generate one-dimensional nano-carbide nanoparticles. The one-dimensional nano-carbide nanoparticles can be nanowires, nanorods, nanotubes, or nanoribbons.

[0007] The catalyst or catalyst precursor is selected from one or more substances containing transition metal elements, preferably one or more elements and compounds of iron, cobalt, and nickel.

[0008] The carbon material is selected from materials containing carbon, preferably one or more of conductive carbon black, graphitized carbon, and biomass carbon.

[0009] The reaction raw materials are one or more of metal oxides, non-metallic elements and non-metallic oxides, and polymer plastics, preferably one or more of tantalum oxide, titanium oxide, silicon powder, silicon dioxide, boron powder and boron oxide, zirconium oxide, hafnium oxide, and niobium oxide.

[0010] The heating temperature is above 900℃, preferably 1000-2800℃. The heating rate is greater than 1000℃ / s. The heating time is 5-80s, preferably 10-70s, and more preferably 20-40s.

[0011] The present invention also aims to provide a one-dimensional nanocarbide, which is prepared by the aforementioned rapid catalytic preparation method for one-dimensional nanocarbide. The one-dimensional nanomaterial is a nanowire, nanorod, nanotube, or nanoribbon, preferably a covalent carbide represented by SiC nanowires and B4C nanowires, a metallic carbide represented by TiC nanorods and TaC nanorods, or a high-entropy carbide nanowire represented by TiHfNbTaC.

[0012] The present invention has the following beneficial effects:

[0013] (1) The present invention places the reaction raw material containing the catalyst or the precursor of the catalyst and the carbon material between two electrodes to achieve rapid and stable Joule heating to obtain one-dimensional nano carbides, which greatly shortens the preparation time in the traditional method.

[0014] (2) The preparation method of the present invention has a high reaction temperature, simple and fast process operation, is easier to control, low cost, low purity requirements of raw materials and wide availability, and can achieve low-cost preparation.

[0015] (3) The preparation method of the present invention can be used to prepare various one-dimensional nanomaterials with good product quality, high purity, uniform and controllable size, and the products have a wide range of applications. Attached Figure Description

[0016] Figure 1 A schematic diagram of the reaction apparatus of the present invention is shown;

[0017] Figure 2 The heating and cooling temperature curves of Embodiment 1 of the present invention are shown;

[0018] Figure 3 (a) shows the I XRD pattern of the SiC nanowires prepared in Example 1 of the present invention; Figure 3 (b) and Figure 3 (c) Shows a SEM image of the SiC nanowire I prepared in Example 1 of the present invention;

[0019] Figure 4 (a) and Figure 4 (b) The XRD pattern and SEM image of the SiC nanowire II prepared in Example 2 of the present invention are shown respectively;

[0020] Figure 5 (a) and Figure 5 (b) The XRD patterns and SEM images of the B4C nanowires prepared in Example 3 of the present invention are shown respectively;

[0021] Figure 6 (a) and Figure 6 (b) The XRD patterns and SEM images of the TiC nanorods prepared in Example 4 of the present invention are shown respectively;

[0022] Figure 7 (a) and Figure 7 (b) The XRD patterns and SEM images of the TaC nanorods prepared in Example 5 of the present invention are shown respectively;

[0023] Figure 8 (a), Figure 8 (b), Figure 8 (c) and Figure 8 (d) The XRD pattern, SEM image, scanning transmission electron microscope image and elemental distribution map of the TiZrHfNbTaC high-entropy carbide nanowires prepared in Example 6 of the present invention are shown respectively. Detailed Implementation

[0024] The present invention will now be described in detail through specific embodiments, and the features and advantages of the present invention will become clearer and more explicit with these descriptions.

[0025] This invention provides a method for the rapid catalytic preparation of one-dimensional nano-carbide nanoparticles. In this method, reactants and carbon materials react under heating conditions, with the gaseous reactants reacting in the presence of a catalyst to obtain one-dimensional nano-carbide nanoparticles. The reactants and carbon materials generate Joule heat under the influence of an electric current, rapidly increasing the temperature and initiating a reaction. The resulting gaseous molecules, under the action of a catalyst, follow a gas-liquid-solid reaction mechanism to generate one-dimensional nano-carbide nanoparticles. The one-dimensional nano-carbide nanoparticles can be nanowires, nanorods, nanotubes, or nanoribbons.

[0026] The catalyst or catalyst precursor is selected from one or more substances containing transition metal elements, preferably from one or more elements and compounds of iron, cobalt, and nickel, more preferably from one or more elements of iron, cobalt, and nickel, such as nitrates, sulfates, chlorides, and acetates of iron, cobalt, and nickel.

[0027] The carbon material is selected from materials containing carbon, preferably one or more of conductive carbon black, graphitized carbon, and biomass carbon.

[0028] The reaction raw materials are one or more of metal oxides, non-metallic elements and non-metallic oxides, and polymer plastics, preferably one or more of tantalum oxide, titanium oxide, silicon powder, silicon dioxide, boron powder and boron oxide, zirconium oxide, hafnium oxide, and niobium oxide.

[0029] The heating temperature is above 1200℃, preferably 1500-2800℃, and more preferably 1800-2500℃. The heating rate is greater than 1000℃ / s. The heating time is 5-80s, preferably 10-70s, and more preferably 20-40s. Any heating method that meets the above heating rate and temperature requirements is acceptable. Rapid heating helps save reaction time and improves reaction efficiency. Under the same reaction time, the higher the temperature, the more complete the reaction, and the greater the content of one-dimensional nano-carbide in the product.

[0030] Preferably, in this invention, the heating includes Joule heating, which utilizes the Joule heat generated by carbon materials under the action of an electric current.

[0031] In this invention, a carbon material film is used to encapsulate the reaction precursor, and two carbon material plugs are used to seal it in a reaction vessel. The two carbon material plugs are connected to the positive and negative terminals of a power source, respectively. When an electric current is passed through, a one-dimensional nano-carbide is obtained.

[0032] The reaction precursor is a reaction raw material containing a catalyst or a catalyst precursor and a carbon material.

[0033] Preferably, the substance containing the transition metal element is dissolved or dispersed in a solvent, the reactants and / or carbon materials are added, mixed, the solvent is separated and removed, and dried; after drying, optionally, carbon materials are added and mixed; to obtain the reaction precursor.

[0034] In the reaction precursor, the molar mass ratio of the reactant to the carbon material is (0.01-0.16) mol:1 g, preferably (0.01-0.12) mol:1 g, and more preferably (0.01-0.08) mol:1 g. Within the above-mentioned range, the resistivity of the reaction precursor can be guaranteed to meet the preparation conditions, thus obtaining suitable Joule heating.

[0035] The molar ratio of the substance containing the transition metal element to the reaction raw materials is (0.0005-0.05):(0.01-0.08), preferably (0.001-0.025):(0.01-0.08), and the molar amount of the substance containing the transition metal element is calculated based on the molar amount of the metal element therein.

[0036] When the reactant is a metal oxide, the molar ratio of the substance containing the transition metal element to the reactant is (0.0001-0.002):(0.01-0.02), preferably (0.0006-0.0014):(0.01-0.02); when the reactant is one or more non-metallic elements and non-metallic oxides, the molar ratio of the substance containing the transition metal element to the reactant is (0.005-0.04):(0.05-0.08), preferably (0.01-0.02):(0.05-0.08).

[0037] The carbon material film is carbon paper, carbon cloth, graphite paper, or carbon fiber film.

[0038] The carbon material plug is preferably a graphite plug.

[0039] After the reaction precursor is sealed within the reaction vessel by two carbon material plugs, the resistance between the two carbon material plugs is 0.1-2Ω, preferably 0.1-1.5Ω, and more preferably 0.1-1Ω. When the resistance between the two carbon material plugs is within the above range, suitable Joule heating can be obtained to carry out the reaction after current is applied.

[0040] The current is 20-120A, preferably 30-100A. Under a given power, the higher the resistance and current, the higher the reaction temperature. Under typical reaction conditions, currents of 70, 80, and 90A correspond to reaction temperatures of approximately 1900, 2100, and 2500℃, respectively.

[0041] The reaction is carried out under anaerobic or oxygen-deficient conditions, such as in a nitrogen and / or argon atmosphere. The oxygen-deficient condition is characterized by an oxygen content of less than 3 wt%, preferably less than 2 wt%.

[0042] This invention also provides one-dimensional nanocarbides prepared using the aforementioned rapid catalytic preparation method, wherein the one-dimensional nanocarbides are nanowires, nanorods, nanotubes, or nanoribbons, preferably covalent carbides represented by SiC nanowires and B4C nanowires, metallic carbides represented by TiC nanorods and TaC nanorods, or high-entropy carbide nanowires represented by TiZrHfNbTaC.

[0043] The nanowires have a diameter of 30-100 nm, preferably 50-80 nm. The nanorods have a diameter of 150-450 nm, preferably 200-400 nm.

[0044] Example

[0045] Example 1

[0046] 5.82 g of Ni(NO3)2·6H2O and 5.82 g of Co(NO3)2·6H2O were added to 100 ml of deionized water, respectively. Then, 4 g of silica powder was added to the catalyst solution, sonicated for 30 minutes, and stirred for 10 hours. After centrifugation to remove the supernatant, the solution was dried to obtain silica loaded with cobalt and nickel ions. The silica was then thoroughly ground and mixed with 5 g of conductive carbon black to obtain the reaction precursor.

[0047] Take 0.5g of the precursor, wrap it in graphite paper, and place it inside a quartz tube. Connect the reactant to the circuit through graphite plugs. Adjust the spacing of the graphite plugs to control the resistance of the reactant at 0.5Ω. Specifically... Figure 1 As shown, after evacuation, inert gas was introduced. The reaction current was controlled by a constant current power supply with a control current of 90A. An infrared temperature detector measured the reactants heating to 2500℃ at a rate of 3000℃ / s, as shown in the temperature curve. Figure 2 As shown. After a reaction of 30 seconds, gray SiC nanowire I powder was obtained.

[0048] The SiC nanowires I obtained in Example 1 were characterized by X-ray diffraction and scanning electron microscopy. Figure 3 The X-ray diffraction pattern in (a) shows that the product is 3C-SiC. Figure 3 (b) The scanning electron microscope image shows that the nanowire product consists of nanowires with a diameter of approximately 60 nm, with a small amount of unreacted carbon adhering to the surface. Figure 3 The scanning electron microscope image in (c) shows that a metal catalyst is attached to the tip of the nanowire, indicating that the growth process of the nanowire follows the gas-liquid-solid reaction mechanism.

[0049] Example 2

[0050] SiC nanowires II were prepared according to the method of Example 1, except that: silicon powder and conductive carbon black of the same mass as in Example 1 were added to a solution of Ni(NO3)2·6H2O and Co(NO3)2·6H2O, sonicated for 30 minutes and stirred for 10 hours, and the supernatant was removed by centrifugation and then dried to obtain the reaction precursor.

[0051] The SiC nanowires II obtained in Example 2 were characterized by X-ray diffraction and scanning electron microscopy, as shown below. Figure 4 (a) and Figure 4 (b). From Figure 4 (b) The scanning electron microscope image shows that the product is uniformly distributed SiC nanowires.

[0052] Example 3

[0053] B4C nanowires were prepared according to the method in Example 1, with the only difference being that 2.90 g of Ni(NO3)2·6H2O and 2.90 g of Co(NO3)2·6H2O were added to 100 ml of deionized water, followed by 0.62 g of boron powder and 0.46 g of boron oxide powder. The mixture was then sonicated for 30 minutes and stirred for 10 hours. After centrifugation to remove the supernatant, the mixture was dried to obtain boron powder and boron oxide loaded with cobalt and nickel ions. These powders were then thoroughly ground and mixed with 1 g of conductive carbon black to obtain the reaction precursor. The reaction input current was 80 A.

[0054] The B4C nanowires obtained in Example 3 were characterized by X-ray diffraction and scanning electron microscopy. Figure 5 X-ray diffraction characterization in (a) confirmed the product as B4C; from Figure 5 Scanning electron microscopy characterization in (b) shows that the product is a B4C nanowire with a diameter of approximately 90 nanometers.

[0055] Example 4

[0056] TiC nanorods were prepared according to the method in Example 1, with the only difference being that 0.3 g of Ni(NO3)2·6H2O and 0.3 g of Co(NO3)2·6H2O were added to 50 ml of deionized water, and then 0.8 g of TiO2 was added to the catalyst solution. The mixture was ultrasonicated for 30 minutes and stirred for 10 hours. After centrifugation to remove the supernatant, the solution was dried to obtain titanium dioxide loaded with cobalt and nickel ions. The above-mentioned catalyst-loaded TiO2 was then thoroughly ground and mixed with 1 g of conductive carbon black to obtain the reaction precursor. The reaction input current was 90 A.

[0057] The TiC nanorods obtained in Example 4 were characterized by X-ray diffraction and scanning electron microscopy. Figure 6 X-ray diffraction characterization in (a) confirmed that the product was TiC and some unreacted TiO2 powder; from Figure 6The scanning electron microscopy characterization in (b) shows that the product is a TiC nanorod with a diameter of approximately 260 nm.

[0058] Example 5

[0059] TaC nanorods were prepared according to the method in Example 1, with the only difference being that: 0.3 g of Ni(NO3)2·6H2O and 0.3 g of Co(NO3)2·6H2O were respectively placed in 50 ml of deionized water, and then 4.4 g of Ta2O5 was added to the catalyst solution, sonicated for 30 minutes and stirred for 10 hours. After centrifugation to remove the supernatant, the solution was dried to obtain Ta2O5 loaded with cobalt and nickel ions. The above-mentioned catalyst-loaded Ta2O5 was then thoroughly ground and mixed with 1 g of conductive carbon black to obtain the reaction precursor. The reaction input current was 80 A.

[0060] The TaC nanorods obtained in Example 5 were characterized by X-ray diffraction and scanning electron microscopy. Figure 7 X-ray diffraction characterization in (a) confirmed that the product was TaC and some unreacted Ta2O5 powder; from Figure 7 The scanning electron microscopy characterization in (b) shows that the product is a TaC nanorod with a diameter of approximately 340 nm.

[0061] Example 6

[0062] TiZrHfNbTaC high-entropy nanowires were prepared according to the method in Example 1, with the only difference being: 0.763g of Fe(NO3)3·9H2O and 1.53g of Ni(NO3)2·6H2O were added to 200ml of deionized water, followed by the addition of 0.8g of TiO2, 1.23g of ZrO2, 2.1g of HfO2, 1.3g of Nb2O5, and 2.2g of Ta2O5 powders to the above solution. The mixture was ultrasonicated for 30 minutes and stirred for 10 hours. After centrifugation to remove the supernatant, the mixture was dried to obtain a mixed metal powder loaded with iron and nickel ions. 1g of the above powder was then thoroughly ground and mixed with 1g of conductive carbon black to obtain the reaction precursor.

[0063] The high-entropy carbide TiZrHfNbTaC nanowires obtained in Example 8 were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Figure 8 X-ray diffraction characterization in (a) confirmed that the product was a carbide, with some unreacted oxides present; from Figure 8 Scanning electron microscopy characterization in (b) shows that the product is nanowires; from Figure 8 The scanning transmission electron microscopy characterization in (c) shows that the diameter of the nanowire is approximately 50-100 nm. Figure 8 (d) The energy-dispersive X-ray spectrum shows that the nanowires are mainly composed of Ti, Zr, Hf, Nb, Ta and C elements, with highly uniform distribution of each element, indicating a high-entropy structure.

[0064] The present invention has been described in detail above with reference to specific embodiments and / or exemplary examples, as well as the accompanying drawings. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for the rapid catalytic preparation of one-dimensional nano-carbide, wherein, under heating conditions, reactants and carbon materials form gaseous reactants, which then react under the action of a catalyst to obtain one-dimensional nano-carbide. The catalyst or catalyst precursor is selected from one or more elements and compounds of iron, cobalt, and nickel. The carbon material is selected from materials containing allotropes of carbon. The reaction raw materials are one or more of metal oxides, non-metallic elements, and non-metallic oxides. The heating temperature is above 900℃. The heating rate is greater than 1000℃ / s. The heating time is 5-80 seconds.

2. The method according to claim 1, characterized in that, The reaction raw materials are one or more of the following: tantalum oxide, titanium oxide, silicon powder, silicon dioxide, boron powder and boron oxide, zirconium oxide, hafnium oxide, and niobium oxide.

3. The method according to claim 1, characterized in that, The carbon material is selected from one or more of conductive carbon black, graphitized carbon, and biomass carbon.

4. The method according to claim 1, characterized in that, The heating temperature is 1000-2800℃. The heating time is 10-70 seconds.

5. The method according to claim 4, characterized in that, The heating time is 20-40 seconds.

6. The method according to claim 1, characterized in that, The heating includes Joule heating, which utilizes the Joule heat generated by carbon materials under the action of an electric current.

7. The method according to claim 1, characterized in that, A carbon material film was used to encapsulate the reaction precursor, and two carbon material plugs were used to seal it in a reaction vessel. The two carbon material plugs were connected to the positive and negative terminals of a power source, respectively. When an electric current was applied, the reaction yielded one-dimensional nano-carbide. The reaction precursor is a reaction raw material containing a catalyst or a catalyst precursor and a carbon material.

8. The method according to claim 7, characterized in that, The substance containing transition metal elements is dissolved or dispersed in a solvent, and reactants and / or carbon materials are added, mixed, the solvent is removed, and dried; after drying, optionally, carbon materials are added and mixed; thus, a reaction precursor is obtained.

9. The method according to claim 7, characterized in that, The carbon material film is carbon paper, carbon cloth, graphite paper, or carbon fiber film. After the reaction precursor is sealed within the reaction vessel by two carbon material plugs, the resistance between the two carbon material plugs is 0.1-2Ω. The current is 20-120A. The reaction is carried out under anaerobic or oxygen-deficient conditions.

10. The method according to claim 9, characterized in that, After the reaction precursor is sealed within the reaction vessel by two carbon material plugs, the resistance between the two carbon material plugs is 0.1-1.5Ω. The current is 30-100A.

11. The method according to claim 10, characterized in that, After the two carbon material plugs seal the encapsulated reaction precursor in the reaction vessel, the resistance between the two carbon material plugs is 0.1-1Ω.

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