A method for synthesizing an ultra-fine nanowire / carbon nanotube composite film by inter-tube confinement induction

Abstract

The present invention relates to the field of controllable preparation of carbon nanotube composites, and specifically to a method for synthesizing ultra-fine nanowire / carbon nanotube composite films by inter-tube confinement induction. This method controllably introduces defects on the carbon nanotube walls through chemical oxidation, plasma treatment, etc., and then introduces transition metals, noble metals, transition metal oxides, etc. between carbon nanotube bundles by methods such as chemical vapor deposition, wet chemical synthesis, solvothermal synthesis, etc. Subsequently, fast heat treatment, etc. is carried out to induce self-assembly to form ultra-fine nanowires confined between carbon nanotube bundles, and the nanowires are oriented and arranged between the carbon nanotubes to form an ordered composite film. By changing the methods of creating defects and introducing nanowire precursors, this method can regulate the structure and composition of the nanowires. The prepared ultra-fine nanowire composite carbon nanotube film has a unique ordered structure and excellent properties, and has broad application prospects in fields such as electrocatalytic overall water splitting, thermal evaporation desalination of seawater, and photothermal coupling catalysis.

Description

Technical Field

[0001] The present invention relates to the field of controllable preparation of carbon nanotube composites, and specifically to a method for inter-tube confinement-induced synthesis of ultra-fine nanowire / carbon nanotube composite films. Background Art

[0002] Carbon nanotubes can be regarded as one-dimensional hollow tubular structures formed by curling graphene, and they have ultra-fine nanotube cavities (0.6 - 2.0 nm). Since the structure of carbon nanotubes has been finely analyzed, their unique hollow tubular structure has attracted extensive attention from researchers. In particular, the synthesis of carbon nanotube composite structures with new structures and new properties using single-walled carbon nanotubes as "templates" has always been a research hotspot in this field.

[0003] For the controllable synthesis of carbon nanotube composite structures, researchers have proposed two types of methods: (1) Utilizing the "capillary action" of the unique nanotube cavities of carbon nanotubes, carbon nanotubes are filled by adsorbing gaseous and liquid precursor sources to prepare one-dimensional tubular structures such as C 60 @carbon nanotubes, I2@carbon nanotubes, metal nanoparticles / nanowires@carbon nanotubes, metal oxide nanoparticles / nanowires@carbon nanotubes, chalcogen allotropes@carbon nanotubes, etc., and it has been found that they have great application potential in nanoelectronic devices, photoelectric detection, catalysis, etc. (Smith B.W. et al. Carbon, 2000, 321, 1 - 2, 169 - 174; Zhang J. et al. Angew. Chem. Int. Ed., 2017, 56, 1850 - 1854; Hart M., et al. Inorg. Chem. 2019, 58, 15216 - 15224). (2) Using the carbon nanotube wall as a "template", coaxial one-dimensional tubular heterojunctions are grown by chemical vapor deposition to prepare carbon nanotube composite structures such as single-walled carbon nanotubes@h-BN, single-walled carbon nanotubes@h-BN@MoS2, etc., and it has been found that they have excellent thermal conductivity enhancement and optoelectronic properties, etc. (Xiang R., et al. Science, 2020, 367, 6477, 537 - 542).

[0004] Although new carbon nanotube composites with excellent properties have been obtained by the above methods, the sample amount is usually very small, which greatly limits their application scope. Moreover, due to the large wall curvature and small tube cavity size of carbon nanotubes, there are problems such as poor controllability, low efficiency, and poor repeatability in preparing carbon nanotube one-dimensional composite structures by filling and coating. Based on this, the present invention proposes a method for highly controllable synthesis of ultra-fine nanowire / carbon nanotube composite films using the inter-tube confinement space of single-walled carbon nanotubes as a "template". Summary of the Invention

[0005] The object of the present invention is to provide a method for synthesizing an ultra-fine nanowire / carbon nanotube composite film by inter-tube confinement induction. Defects are controllably created between carbon nanotubes, and a precursor is adsorbed at the defects. Through self-assembly or rapid heat driving, ultra-fine nanowires confined between the tubes are formed, and a carbon nanotube composite film with a uniform and ordered structure is obtained. By introducing transition metal oxides through low-pressure chemical vapor deposition and performing high-temperature carbonization, an ultra-fine transition metal carbide / carbon nanotube composite film confined between the tubes is prepared; by using a wet chemical method to reduce metal acetylacetonate and self-assembling between the tubes, an ultra-fine metal nanowire / carbon nanotube composite film is formed; by using a solvothermal method to decompose transition metal polyoxometalates to form metal oxides that nucleate and grow between the tubes, and performing heat treatment, an ultra-fine transition metal oxide nanowire / carbon nanotube composite film is obtained. The ultra-fine nanowires confined between the tubes have the characteristics of monodispersity and oriented arrangement. The composite carbon nanotube film constructed by this method has broad application prospects in the field of energy storage and conversion.

[0006] The technical solution of the present invention:

[0007] A method for synthesizing an ultra-fine nanowire / carbon nanotube composite film by inter-tube confinement induction. Defects are controllably introduced onto the walls of high-quality carbon nanotubes by chemical oxidation or plasma treatment methods. Transition metals, noble metals or transition metal oxides are introduced between carbon nanotube bundles by chemical vapor deposition, wet chemical synthesis or solvothermal synthesis methods. Through rapid heat treatment, self-assembly is induced to form ultra-fine nanowires confined between the carbon nanotubes, and a composite film with ultra-fine nanowires oriented between the carbon nanotubes is obtained; by changing the methods of creating defects and introducing nanowire precursors, the structure and composition of the nanowires are regulated.

[0008] In the method for synthesizing an ultra-fine nanowire / carbon nanotube composite film by inter-tube confinement induction, the carbon nanotube film used is a high-quality single-walled carbon nanotube film with a film thickness of 1 - 2 μm. After defects are introduced by chemical oxidation or plasma, it still has good mechanical properties and can maintain a self-supporting structure.

[0009] In the method for synthesizing an ultra-fine nanowire / carbon nanotube composite film by inter-tube confinement induction, defects are controllably introduced onto the walls of carbon nanotubes by chemical oxidation. During the chemical oxidation process, the defect density and size are regulated by using oxidants with different oxidation abilities, changing the concentration of the oxidant and the oxidation time; among them, the oxidant is strongly oxidizing KMnO4 or H2SO4, weakly oxidizing H2O2, or oxidizing acid HNO3.

[0010] The method for synthesizing ultra-fine nanowire / carbon nanotube composite films by inter-tube confinement induction uses plasma treatment to controllably introduce defects on the carbon nanotube walls, and uses plasma sources with different chemical reaction activities, changes the power and treatment time for generating plasma to regulate the density and size of the introduced defects; among them, the plasma source is O3 or O2 with high chemical reaction activity, or H2 with medium chemical reaction activity, or inert N2 or Ar.

[0011] The method for synthesizing ultra-fine nanowire / carbon nanotube composite films by inter-tube confinement induction introduces transition metals, noble metals or transition metal oxides between carbon nanotubes through chemical vapor deposition, wet chemical synthesis or solvothermal synthesis methods, and forms ultra-fine nanowires confined between carbon nanotubes after heat treatment.

[0012] The method for synthesizing ultra-fine nanowire / carbon nanotube composite films by inter-tube confinement induction is that the precursor is deposited and grown by defect induction, and the diameter of the prepared ultra-fine nanowires is less than 5 nm and is oriented between the carbon nanotubes, forming a structurally ordered carbon nanotube composite film.

[0013] The method for synthesizing ultra-fine nanowire / carbon nanotube composite films by inter-tube confinement induction uses low-pressure chemical vapor deposition method to synthesize ultra-fine transition metal carbide nanowires confined between tubes. Under negative pressure conditions, a metal organic compound is used as the precursor source, and below the decomposition temperature of the precursor source, transition metal oxide clusters are deposited on the carbon nanotube walls containing defects, and the temperature is rapidly raised to 700-1700 °C at a heating rate of 50-500 °C / s, and CH4 carbon source is introduced to carbonize for 1-5 min, and at the same time, ultra-fine transition metal carbide nanowires are agglomerated in the inter-tube confinement space; among them, the transition metal carbide is one or more of Mo2C, W2C, TaC or ReC, and the inter-tube confined transition metal carbide / single-walled carbon nanotube composite film has excellent electrocatalytic hydrogen evolution performance.

[0014] The method for synthesizing ultra-fine nanowire / carbon nanotube composite films by inter-tube confinement induction uses wet chemical method to synthesize ultra-fine metal nanowires confined between tubes. Using metal acetylacetonate as the precursor, adding a surfactant and heating in oleylamine at 130-220 °C for 1-300 min to generate ultra-fine metal nanowires between the carbon nanotube film bundles; among them, the metal is one or more of Pt, Pd, Fe, Co, Ni, Mo, Ru, Rh; the surfactant is one or more of dodecyl dimethyl ammonium bromide, cetyl trimethyl ammonium bromide, cetyl trimethyl ammonium chloride, octadecyl trimethyl ammonium bromide, docosyl dimethyl ammonium bromide, and the inter-tube confined ultra-fine metal nanowire / single-walled carbon nanotube composite film has excellent interfacial water evaporation performance.

[0015] The described method for synthesizing ultra-fine nanowire / carbon nanotube composite films by inter-tube confinement induction, where the ultra-fine nanowires are confined and aligned directionally between carbon nanotubes, have a specific structural orientation, and are widely used in the fields of electrocatalytic overall water splitting, thermal evaporation desalination of seawater, photothermal coupling catalysis, or solar interfacial water evaporation.

[0016] The design concept of the present invention is:

[0017] The present invention utilizes the inter-tube grooves of single-walled carbon nanotubes as a confinement space to controllably synthesize self-supporting ultra-fine nanowire / carbon nanotube composite films. Due to the characteristic of the ultra-fine tube diameter of single-walled carbon nanotubes, a tiny confinement space is formed between tubes. Defects are controllably created on the carbon nanotube walls, and then precursors are introduced at the carbon nanotube defects through methods such as solvothermal reaction, chemical vapor deposition, and wet chemical synthesis to self-assemble into ultra-fine nanowires. The ultra-fine nanowires confined between tubes have a consistent orientation, and the composite film has excellent properties.

[0018] The advantages and beneficial effects of the present invention are:

[0019] 1. The present invention provides a preparation method for inter-tube confined ultra-fine nanowire / carbon nanotube composite films, which can controllably prepare monodisperse ultra-fine nanowires with directional alignment by utilizing the inter-tube confinement effect of carbon nanotubes.

[0020] 2. The present invention can introduce transition metals, metal oxides, metal carbides, etc. between carbon nanotubes by various methods such as chemical vapor deposition, solvothermal reaction, and wet chemical synthesis. By changing the methods and process conditions for introducing nanowires, the structure and properties of the composite film can be regulated, and it has strong compatibility and controllability.

[0021] 3. The method of the present invention uses a carbon nanotube network with a large specific surface area and high conductivity as a carrier. The inter-tube confinement enables better contact between the ultra-fine nanowires and carbon nanotubes, thereby improving their stability and having excellent performance in enhancing electron and phonon transport.

[0022] 4. The inter-tube confined transition metal carbide ultra-fine nanowire / carbon nanotube composite films and metal ultra-fine nanowire carbon nanotube composite films prepared by the method of the present invention have good application prospects in the fields of electrocatalytic overall water splitting, photothermal conversion, and solar interfacial water evaporation. Brief Description of the Drawings

[0023] Figure 1 . Schematic diagram of the process for preparing inter-tube confined ultra-fine transition metal carbide nanowire / carbon nanotube composite films by chemical vapor deposition.

[0024] Figure 2 . Scanning transmission electron microscope photograph of inter-tube confined ultra-fine W2C nanowire / carbon nanotube composite films.

[0025] Figure 3 . Hydrogen evolution curve of the confined ultrafine W2C nanowire / carbon nanotube composite film between tubes (counter electrode: graphite electrode; reference electrode: Ag / AgCl electrode; electrolyte solution: 0.5 mol / L H2SO4 solution).

[0026] Figure 4 . Schematic diagram of the process for preparing the confined transition metal ultrafine nanowire / carbon nanotube composite film between tubes by the wet chemical method.

[0027] Figure 5 . Transmission electron microscope photograph of the confined transition metal ultrafine nanowire / carbon nanotube composite film between tubes.

[0028] Figure 6 . Overall water splitting performance of the confined transition metal ultrafine nanowire / carbon nanotube composite film between tubes (electrolyte solution: 1 mol / L KOH aqueous solution).

[0029] Figure 7 . Performance of the confined transition metal ultrafine nanowire / carbon nanotube composite film between tubes for solar-thermal interfacial water evaporation and desalination of seawater.

[0030] Figure 8 . Transmission electron microscope photograph of the transition metal carbide particle / carbon nanotube composite film. Detailed implementation mode

[0031] In the specific implementation process, the present invention controllably introduces defects on the carbon nanotube wall through chemical oxidation, plasma treatment, etc., and then uses methods such as low-pressure chemical vapor deposition, wet chemical synthesis, and solvothermal synthesis to introduce precursors such as transition metals, noble metals, and transition metal oxides between the carbon nanotubes. After heat treatment and other inductions, self-assembly is formed to obtain ultrafine nanowires confined between the carbon nanotube bundles. The nanowires are oriented between the carbon nanotubes to obtain an ordered composite film of ultrafine nanowires / carbon nanotubes. By introducing defects on the carbon nanotube wall, regulating the process conditions of the precursor introduction process, and changing the types of precursor sources, etc., a confined metal / metal oxide / transition metal carbide ultrafine nanowire / carbon nanotube composite film between tubes is prepared.

[0032] Next, the present invention will be further described in detail through examples and drawings.

[0033] Example 1

[0034] As Figure 1 shown, the process for preparing the confined transition metal carbide ultrafine nanowire / carbon nanotube composite film by chemical vapor deposition, the specific experimental steps are as follows:

[0035] (1) Controllably create defects on the carbon nanotube wall

[0036] Prepare a volume ratio of V硫酸 : V 硝酸 = 5:1 mixed acid solution, place the single-walled carbon nanotubes grown by floating catalytic chemical vapor deposition in 10 - 30 ml of the mixed acid solution and heat to 70 °C for 20 h. Wash with deionized water until neutral and vacuum filter to form a film to obtain a single-walled carbon nanotube film with defects on the tube wall, the thickness of which is 2 - 3 μm. A large number of defect sites are formed on the carbon nanotube tube wall by the mixed acid.

[0037] (2) Low-pressure chemical vapor deposition of transition metal oxides

[0038] Take an acid-treated single-walled carbon nanotube film with a size of 1×1 cm, and take 30 mg of tungsten tricarbonyl trimethylbenzene powder and put them into a quartz tube together. Use vacuum sealing to reduce the vacuum in the quartz tube to a pressure of 1×10 -4 ~ 1×10 -1 Pa and then seal. Put the sealed quartz tube into a muffle furnace and heat-treat at 300 °C for 10 h to obtain a single-walled carbon nanotube composite film with tungsten oxide nanoparticles dispersed between the tubes.

[0039] (3) Carbonization and assembly of transition metal oxides to form nanowires

[0040] Place the film obtained in step (2) in a tubular furnace, introduce a mixed gas (by volume percentage, methane 2%, hydrogen 10%, argon 88%), and heat at a heating rate of 500 °C / min to 1500 °C for heat treatment for 5 min and then cool with the furnace. W2C nanowires are formed in the inter-tube confinement to obtain an ultrafine W2C nanowire / carbon nanotube composite film.

[0041] (4) Structure characterization of the composite film

[0042] As Figure 2 shown, ultrasonically disperse the composite film and drop it onto a copper mesh microgrid. Use a transmission electron microscope to observe the microstructure of the ultrafine W2C nanowire / carbon nanotube composite film. The ultrafine W2C nanowires are monodispersed between the carbon nanotube bundles, with a diameter of 1 - 1.5 nm, an average length of 10 nm, and a consistent orientation.

[0043] (5) Electrochemical hydrogen evolution performance test of the composite film

[0044] Test the electrocatalytic hydrogen evolution performance of the ultrafine W2C nanowire / single-walled carbon nanotube film obtained in step (3). In a three-electrode electrochemical workstation (working electrode: rotating disk electrode; counter electrode: graphite electrode; reference electrode: Ag / AgCl electrode; electrolyte solution: 0.5 mol / L H2SO4 solution), perform linear scanning at a scanning rate of 5 mV / s. As Figure 3 shown, the test results show that the initial potential of the electrocatalytic hydrogen evolution of this composite film is 42 mV, 10 mA / cm2 The overpotential at the current density is 72 mV.

[0045] Example 2

[0046] As Figure 4 shown, in the process of preparing the intertube-confined ultrafine transition metal nanowire / carbon nanotube composite film by the wet chemical method, the specific experimental steps are as follows:

[0047] (1) Controllably creating defects on the carbon nanotube wall

[0048] The single-walled carbon nanotube film directly collected after growth by the floating catalyst chemical vapor deposition method was placed in a plasma cleaner. The plasma treatment power used was 7 W, and the treatment time was 1 min. Plasma was used to create defects on the carbon nanotube wall to obtain a single-walled carbon nanotube film rich in defects on the wall. The thickness of this single-walled carbon nanotube film was 1 - 2 μm, and the defects loaded on the wall were mainly carbon vacancies, point defects, etc.

[0049] (2) Depositing transition metals by the wet chemical method

[0050] A certain amount of platinum acetylacetonate, iron acetylacetonate, molybdenum acetylacetonate, nickel acetylacetonate, cobalt acetylacetonate (20 mg each) and 50 mg of cetyltrimethylammonium bromide, as well as 80 mg of anhydrous glucose, were placed in 5 ml of oleylamine solvent and ultrasonically dispersed and dissolved to form a homogeneous solution. The carbon nanotube film rich in defects was placed in this solution and heated in an oil bath at 160 °C for 60 min. After the reaction ended, the film was taken out and washed with absolute ethanol to remove the surfactant, and an ultrafine PtFeCoNiMo nanowire / single-walled carbon nanotube composite film was obtained.

[0051] (3) Structural characterization of the composite film

[0052] Same as step (4) of Example 1. As Figure 5 shown, after the composite film was ultrasonically dispersed, it was dropped onto a copper mesh microgrid, and a transmission electron microscope was used to observe the microstructure of the ultrafine PtFeCoNiMo nanowire / single-walled carbon nanotube composite film. It was monodispersed between the bundles of carbon nanotubes, with an average diameter of 1.56 nm and an average length of 20 nm, and had a consistent orientation.

[0053] (4) Electrochemical catalytic overall water splitting performance test of the composite film

[0054] The electrochemical catalytic overall water splitting performance of the ultrafine PtFeCoNiMo nanowire / single-walled carbon nanotube composite film obtained in test step (2) was tested. A 1 mol / L KOH aqueous solution was used as the electrolyte, and linear scanning was performed at a scanning rate of 5 mV / s. As Figure 6 shown, the test results showed that this composite film could reach 10 mA·cm at a voltage of 1.667 V.-2 Efficient overall water splitting with current density

[0055] Example 3

[0056] As Figure 4 shown, in the process of preparing the intertubular-confined transition metal ultrafine nanowire / carbon nanotube composite film by the wet chemical method, the specific experimental steps are as follows:

[0057] (1) Controllably creating defects on the carbon nanotube wall

[0058] Same as step (1) of Example 1.

[0059] (2) Depositing various transition metals by the wet chemical method

[0060] Same as step (2) of Example 2.

[0061] (3) Structural characterization of the composite film

[0062] Same as step (4) of Example 1. After ultrasonic dispersion of the composite film, it was dropped onto a copper mesh microgrid, and the transmission electron microscope was used to observe the microstructure of the ultrafine PtFeCoNiMo nanowire / single-walled carbon nanotube composite film. The ultrafine PtFeCoNiMo nanowires were monodispersed between the carbon nanotube bundles, with an average diameter of 1.44 nm and an average length of 10.3 nm, and had a consistent orientation.

[0063] (4) Testing the interfacial thermal evaporation performance of the composite film

[0064] Take the composite film prepared in step (2) and put it into the thermal evaporation performance testing equipment. Use wood pulp fiber as the water channel to absorb water and transport it to the upper composite film. Use polytetrafluoroethylene as the structural support mold to separate the composite film from seawater and prevent heat dissipation. As Figure 7 shown, after 6 h of testing, the thermal evaporation performance of the transition metal ultrafine nanowire carbon nanotube composite film under one sun illumination was obtained, and the evaporation efficiency was 1.2 kg·m -2 ·h -1 .

[0065] Example 4

[0066] Prepare the intertubular-confined ultrafine WO3 nanowire / carbon nanotube composite film by the solvothermal method. The specific experimental steps are as follows:

[0067] (1) Controllably creating defects on the carbon nanotube wall

[0068] Same as step (1) of Example 2.

[0069] (2) Solvothermal synthesis of ultrafine WO3 nanowires

[0070] First, take 0.1 g of tungstic acid (WO3·H2O) and dissolve it in 20 mL of 20% hydrogen peroxide aqueous solution. Put the single-walled carbon nanotube film in (1) and this solution together into a 40 mL autoclave, and heat it in a muffle furnace at a heating rate of 10 °C / min to 110 °C. After keeping it warm for 3 h, cool it to room temperature with the furnace. Then take out the film and wash it repeatedly with deionized water to obtain an ultrafine WO3 nanowire / carbon nanotube composite film.

[0071] (3) Structural characterization of the composite film

[0072] Same as step (4) of Example 1. After ultrasonic dispersing the composite film, drop it onto a copper mesh microgrid, and use a transmission electron microscope to observe the microstructure of the ultrafine WO3 nanowire / carbon nanotube composite film. The ultrafine WO3 nanowires are monodispersed between the carbon nanotube bundles, with a diameter of 1 - 2 nm, an average length of about 5 nm, and having a consistent orientation.

[0073] Comparative Example 1

[0074] Transition metal carbide nanoparticle / carbon nanotube composite film, the specific steps are as follows:

[0075] (1) Use the floating catalyst chemical vapor deposition method to collect a single-walled carbon nanotube film, cut a 1×1 cm size and take 20 mg of tungsten hexacarbonyl powder and put them together into a quartz tube. Vacuum seal the quartz tube and reduce the vacuum inside the quartz tube to a pressure of 1×10 -4 ~1×10 -1 Pa and then seal it. Put the sealed quartz tube into a muffle furnace at 230 °C for heat treatment for 5 h.

[0076] (2) Same as step (3) of Example 1

[0077] (3) Step (4) of Example 1. The results of transmission electron microscope characterization are as Figure 8 shown. It can be seen from the figure that no ultrafine nanowires are formed, and nanoparticles with a wide size distribution and obvious aggregation are supported on the carbon nanotubes. The average diameter of the nanoparticles reaches 10 nm. At the same time, due to the aggregation of small-sized oxide particles, the dispersibility and uniformity of the nanoparticles in the composite film are poor.

[0078] The results of the examples and comparative examples show that the particles of single-walled carbon nanotubes without structural defects on the tube wall are larger after chemical vapor deposition, and the larger-sized particles tend to agglomerate into even larger particles during the subsequent heat treatment process. Therefore, by changing the manufacturing defects and introducing nanowire precursors, the structure and composition of nanowires can be regulated, and the defect-introducing step in the pretreatment of single-walled carbon nanotubes promotes the growth of nanowires confined between tubes. The ultrafine nanowire composite carbon nanotube film prepared by this method has a unique ordered structure and excellent properties, and has broad application prospects in the fields of energy storage and conversion such as electrocatalytic overall water splitting, thermal evaporation desalination of seawater, photothermal coupling catalysis, and interfacial water evaporation.

[0079] Although the present invention has been described in detail with general descriptions and specific embodiments above, modifications or improvements can be made based on the present invention, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A method for synthesizing an ultra-fine nanowire / carbon nanotube composite film by inter-tube confinement induction, characterized in that, Controllably introduce defects on the walls of high-quality carbon nanotubes by chemical oxidation or plasma treatment methods. Introduce transition metals, noble metals, or transition metal oxides between carbon nanotube bundles by chemical vapor deposition, wet chemical synthesis, or solvothermal synthesis methods. Induce self-assembly through rapid heat treatment to form ultra-fine nanowires confined between carbon nanotubes, and obtain a composite film with ultra-fine nanowires aligned between carbon nanotubes; by changing the methods of creating defects and introducing nanowire precursors, control the structure and composition of the nanowires. The carbon nanotube film used is a high-quality single-walled carbon nanotube film with a film thickness of 1 - 2 μm. After introducing defects by chemical oxidation or plasma, it still has good mechanical properties and can maintain a self-supporting structure. Introduce transition metals, noble metals, or transition metal oxides between carbon nanotubes by chemical vapor deposition, wet chemical synthesis, or solvothermal synthesis methods, and form ultra-fine nanowires confined between carbon nanotubes after heat treatment. Synthesize ultra-fine transition metal carbide nanowires confined between tubes by low-pressure chemical vapor deposition method. Under negative pressure conditions, use metal organic compounds as the precursor source. Deposit transition metal oxide clusters on the walls of carbon nanotubes containing defects at a temperature lower than the decomposition temperature of the precursor source. Rapidly heat to 700 - 1700 °C at a heating rate of 50 - 500 °C / s, and introduce CH4 carbon source to carbonize for 1 - 5 min. At the same time, agglomerate to form ultra-fine transition metal carbide nanowires in the confined space between tubes; among them, the transition metal carbide is one or more of Mo2C, W2C, TaC, or ReC, and the composite film of transition metal carbide / single-walled carbon nanotube confined between tubes has excellent electrocatalytic hydrogen evolution performance. Synthesize ultra-fine metal nanowires confined between tubes by wet chemical method. Use metal acetylacetonate as the precursor, add surfactants and heat in oleylamine at 130 - 220 °C for 1 - 300 min to generate ultra-fine metal nanowires between carbon nanotube film bundles; among them, the metal is one or more of Pt, Pd, Fe, Co, Ni, Mo, Ru, Rh; the surfactant is one or two or more of dodecyl dimethyl ammonium bromide, cetyl trimethyl ammonium bromide, cetyl trimethyl ammonium chloride, octadecyl trimethyl ammonium bromide, docosyl dimethyl ammonium bromide, and the composite film of ultra-fine metal nanowires / single-walled carbon nanotube confined between tubes has excellent interfacial water evaporation performance.

2. The method for synthesizing an ultra-fine nanowire / carbon nanotube composite film by inter-tube confinement induction according to claim 1, wherein Controllably introduce defects on the walls of carbon nanotubes by chemical oxidation method. During the chemical oxidation process, control the defect density and size by using oxidants with different oxidation abilities, changing the concentration of the oxidant, and the oxidation time; among them, the oxidant is strongly oxidizing KMnO4 or H2SO4, weakly oxidizing H2O2, or oxidizing acid HNO3.

3. The method for synthesizing an ultra-fine nanowire / carbon nanotube composite film by confined induction between tubes according to claim 1, characterized in that, Controllably introduce defects on the walls of carbon nanotubes by plasma treatment. Use plasma sources with different chemical reaction activities, change the power of generating plasma and the treatment time to control the density and size of the introduced defects; among them, the plasma source is highly chemically reactive O3 or O2, or moderately chemically reactive H2, or inert N2 or Ar.

4. The method for synthesizing an ultra-fine nanowire / carbon nanotube composite film by confined induction between tubes according to claim 1, characterized in that The precursor grows by defect-induced deposition, and the prepared ultra-fine nanowires have a diameter of less than 5 nm and are oriented between the carbon nanotubes, forming a carbon nanotube composite film with an ordered structure.

5. The method for synthesizing an ultra-fine nanowire / carbon nanotube composite film by inter-tube confinement induction according to claim 1, characterized in that, The ultra-fine nanowires are confined and oriented between the carbon nanotubes, with a specific structural orientation, and are widely used in the fields of electrocatalytic overall water splitting, thermal evaporation desalination of seawater, photothermal coupling catalysis, or solar interface water evaporation.

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