A method for defect-induced synthesis of carbon nanomaterials embedded metal nanoparticle composite thin film

Abstract

This invention relates to the field of controllable preparation of macroscopic composites of carbon nanomaterials, specifically a method for defect-induced synthesis of composite films of carbon nanomaterials with embedded metal nanoparticles. Defects are controllably created on high-quality carbon nanomaterial films using methods such as plasma etching and chemical oxidation. Under heating conditions, different metal targets are bombarded by magnetron sputtering, causing nucleation and growth of metal clusters / nanoparticles at the defects, resulting in a composite film with monodisperse metal nanoparticles embedded in the carbon nanomaterial. By controlling the defects in the carbon nanomaterial and the magnetron sputtering process conditions, the dispersion and size of the metal nanoparticles can be adjusted, making their size precisely tunable in the sub-nanometer to ten-nanometer range. The metal nanoparticles of different compositions embedded in the carbon nanomaterial film prepared by this method exhibit stronger interactions between the metal particles and the carbon nanomaterial support, showing broad application prospects in energy storage and conversion, sensing and monitoring, catalysis, and other fields.

Description

Technical Field

[0001] This invention relates to the field of controllable preparation of macroscopic nanomaterial composites of carbon nanomaterials, specifically a method for defect-induced synthesis of composite thin films of carbon nanomaterials with embedded metal nanoparticles. Background Technology

[0002] Low-dimensional carbon nanomaterials, represented by carbon nanotubes and graphene, possess properties such as high electrical and thermal conductivity, excellent mechanical properties, and high chemical stability. Macroscopic materials such as fibers, films, and sponges constructed using low-dimensional carbon nanomaterials as building blocks have abundant pore structures and large specific surface areas, making them ideal carrier materials for supporting metal nanoparticles. They have broad application prospects in sensing, catalysis, and energy storage and conversion.

[0003] To realize the application of metal nanoparticles in the field of electrocatalysis, researchers often support them on carbon nanomaterials. Various methods for preparing such metal nanoparticle / carbon nanocomposites have been developed, such as: (1) In-situ pyrolysis method, in which a mixture of organic matter and metal compound is decomposed and reduced at high temperature to obtain metal nanoparticle / carbon nanomaterials. This method is simple to operate, easy to scale up, and has strong compatibility. However, the size and dispersion of the prepared nanoparticles cannot be controlled, and the mechanical strength of the carbon nanomaterials formed by pyrolysis of organic matter is poor; (2) Impregnation and support method, in which carbon nanomaterials are impregnated in a metal salt solution and then reduced by heat treatment to prepare metal nanoparticle / carbon nanomaterials. This method is simple to operate. (3) Wet chemical synthesis method: metal nanoparticles with specific morphology can be obtained by using surfactants and controlling their nucleation and growth conditions in solution, and then they are supported on nano-carbon materials. This method has strong controllability and can obtain high-density catalyst nanoparticles, but the size of the nanoparticles prepared is too large (>10nm), and the bonding between the particles and nano-carbon materials is poor. (4) Physical deposition method: metal particles are deposited on nano-carbon materials by sputtering and bombardment to form metal nanoparticles. It has the advantages of strong controllability, high efficiency and good repeatability, but it is difficult to obtain high-density monodisperse small-sized metal nanoparticles.

[0004] In summary, metal nanoparticle / carbon nanocomposites possess excellent properties, but their controllable preparation still faces some challenges: (1) The size and dispersion of metal nanoparticles are inversely proportional, making the preparation of high-density, small-sized (<5nm) metal nanoparticles extremely difficult. (2) There is a lack of universal methods for preparing metal nanoparticles with different compositions, and most methods suffer from poor controllability and reproducibility. (3) The interaction between metal nanoparticles and carbon nanomaterials is weak, resulting in high resistance to electron and proton transport in electrocatalytic reactions and poor catalytic performance. Summary of the Invention

[0005] The purpose of this invention is to provide a method for defect-induced synthesis of composite films containing embedded metal nanoparticles in carbon nanomaterials. Defects can be controlled on carbon nanomaterials by chemical oxidation or plasma etching, and different metal targets are bombarded by magnetron sputtering to induce the formation of metal nanoparticles embedded in the carbon nanomaterials. The composite film has excellent physicochemical properties and broad application prospects.

[0006] The technical solution of the present invention:

[0007] A method for defect-induced synthesis of composite films containing embedded metal nanoparticles in carbon nanomaterials involves introducing defects into the carbon nanomaterial film using plasma etching or chemical oxidation, bombarding different metal targets with magnetron sputtering under heating conditions, and nucleating and growing metal clusters / nanoparticles at the defects to obtain composite films containing embedded metal nanoparticles in carbon nanomaterials. By controlling the defects in the carbon nanomaterial film and the magnetron sputtering process conditions, metal nanoparticles with adjustable density, size, and dispersion can be obtained, with their size precisely adjustable in the sub-nanometer to ten-nanometer range.

[0008] The method for defect-induced synthesis of composite thin films with embedded metal nanoparticles in nanocarbon materials uses nanocarbon materials composed of single-walled carbon nanotubes, graphene, graphyne, or carbon nanofibers. The characteristic of this type of film is that it remains an independent and self-supporting macroscopic body with good conductivity even after defects are introduced by plasma etching or chemical oxidation.

[0009] The method for defect-induced synthesis of nano-carbon materials with embedded metal nanoparticles involves bombarding different metal targets with magnetron sputtering, controlling the sputtering power and heating temperature during the magnetron sputtering process, so that metal particles are preferentially adsorbed at the defect sites, and after anchoring, metal clusters / nanoparticles are nucleated and grown to obtain nano-carbon materials with embedded metal nanoparticles composite films.

[0010] The method for defect-induced synthesis of nanocarbon materials with embedded metal nanoparticles in the composite film prepared is wherein the metal nanoparticles in the macroscopic body of the composite film are transition metals or noble metals.

[0011] The method for defect-induced synthesis of nanocarbon materials with embedded metal nanoparticle composite films, wherein the transition metal is Fe, Co, Ni, Ti, Cu, Ru, Rh, Mo, W, Re or Ta, and the noble metal is Au, Ag, Pt, Pd or Ir.

[0012] The method for defect-induced synthesis of nano-carbon material embedded with metal nanoparticle composite films involves plasma etching to controllably introduce defects onto the surface of the nano-carbon material film. Depending on the chemical stability of the nano-carbon material, the plasma source can be an inert gas with different chemical reactivity, a moderately chemically active hydrogen gas, or a weakly chemically active inert gas. Furthermore, the chemical reactivity of the gas is matched with the plasma power and time to obtain a G / D ratio of 5 to 20 for the self-supporting nano-carbon material film.

[0013] The method for defect-induced synthesis of nano-carbon materials with embedded metal nanoparticle composite films uses inert gases of different chemical reactivity, such as highly chemically active oxygen, water vapor, carbon monoxide, or ammonia, and weakly chemically active argon or nitrogen. For hydrogen plasma daughter products: power 5-50W, time 100-1500s; for oxygen plasma daughter products: power 2-20W, time 10-100s.

[0014] The method for defect-induced synthesis of nano-carbon materials with embedded metal nanoparticles in composite films requires heating during the magnetron sputtering process. The heating temperature is controlled within the range of 100 to 900°C to stabilize the metal nanoparticles and embed them in the defects.

[0015] The method for defect-induced synthesis of nanomaterials with embedded metal nanoparticles composite films involves treating high-quality single-walled carbon nanotube films with 30-50W hydrogen plasma for 1000-1500s to create high-density defects. During magnetron sputtering, the heating temperature is controlled at 100-400℃, the sputtering power is controlled at 0.5-50W, and the sputtering time of high-purity platinum target is 5-100s, thereby obtaining a single-walled carbon nanotube composite film with embedded high-density sub-nanometer platinum clusters.

[0016] The method described above for defect-induced synthesis of nano-carbon materials with embedded metal nanoparticles composite films, in which the nanoparticles and the nano-carbon support have stronger interactions, exhibit excellent electrocatalytic hydrogen evolution performance in alkaline environments, and are widely used in electrocatalytic hydrogen evolution, electrocatalytic carbon dioxide reduction, gas sensing, or photothermal interface water evaporation.

[0017] The design concept of this invention is:

[0018] This invention controllably introduces defects into carbon nanomaterials and utilizes heating during sputtering to induce the deposition of high-density, small-sized metal nanoparticles, thereby obtaining a carbon nanomaterial composite film with embedded metal nanoparticles. Highly catalytically active particles or clusters are successfully loaded onto the surface of the carbon nanomaterial while maintaining a complete internal conductive network.

[0019] In addition, this invention adjusts the dispersion, size and density of metal nanoparticles by controlling the degree of defects in nano-carbon materials and the magnetron sputtering process conditions, and makes their size precisely adjustable in the sub-nanometer to ten-nanometer range.

[0020] The advantages and beneficial effects of this invention are:

[0021] 1. This invention provides a method for preparing high-density, small-sized metal nanoparticles by defect-induced deposition. The method anchors the metal nanoparticles by introducing defects on the surface of nano-carbon materials, resulting in stronger interaction between the nanoparticles and the carrier.

[0022] 2. This invention can control the size and dispersion of the prepared metal nanoparticles by changing the degree of defects in the nano-carbon material and the magnetron sputtering conditions. By changing the target material, metal nanoparticles with different compositions can be obtained, which has strong compatibility and controllability.

[0023] 3. The method of the present invention uses a large specific surface area and highly conductive single-walled carbon nanotube network as a support. The prepared metal nanoparticles are anchored on the surface of the nano-carbon film to become highly active catalytic sites. The overall composite film can be directly used as a self-supporting electrocatalytic electrode. Attached Figure Description

[0024] Figure 1 Transmission electron microscopy (TEM) image of a single-walled carbon nanotube film after plasma etching.

[0025] Figure 2 Transmission electron microscopy (TEM) images of single-walled carbon nanotube composite films embedded with Cu nanoparticles prepared by magnetron sputtering.

[0026] Figure 3 Size distribution of nanoparticles in Cu nanoparticle / single-walled carbon nanotube composite films prepared by magnetron sputtering. In the figure, the horizontal axis represents particle size (nm).

[0027] Figure 4 Transmission electron microscopy (TEM) images of Pt nanoparticle / single-walled carbon nanotube composite films prepared by magnetron sputtering.

[0028] Figure 5 Size distribution of nanoparticles in Pt nanoparticle / single-walled carbon nanotube composite films prepared by magnetron sputtering. In the figure, the horizontal axis represents particle size (nm).

[0029] Figure 6 Linear voltammetric curves for electrocatalytic hydrogen evolution of small-sized Pt nanoparticle / single-walled carbon nanotube composite films. In the figure, the horizontal axis represents potential (V vs RHE), and the vertical axis represents current density (mA cm⁻¹). -2 ). Detailed Implementation

[0030] In its implementation, this invention employs methods such as plasma etching and chemical oxidation to create defects on the surface of high-quality nanomaterials (e.g., graphene, graphyne, carbon nanotubes, carbon nanofibers). Under heating conditions, different metal targets are bombarded by magnetron sputtering, and the sputtering power, deposition time, and heating temperature are controlled to prepare nanomaterial composite films with embedded metal nanoparticles. By controlling the defect creation and sputtering deposition conditions, the density and size of the metal nanoparticles in the composite film are controlled, and its performance in reactions such as electrocatalytic hydrogen evolution, electrocatalytic carbon dioxide reduction, and interfacial water evaporation is tested.

[0031] The present invention will now be further described in detail through examples.

[0032] Example 1

[0033] In this embodiment, a composite film of single-walled carbon nanotubes embedded with Cu nanoparticles was prepared. The specific experimental steps are as follows:

[0034] (1) Defect introduction

[0035] The single-walled carbon nanotube film was transferred to a suspended molybdenum ring and placed in an air plasma chamber. The sample chamber was then evacuated to a pressure of 3 × 10⁻⁶. -5 Pa was treated with hydrogen plasma at a power of 10 W and a flow rate of 30 sccm for 200 s. The morphology of the sample after treatment is as follows. Figure 1 As shown.

[0036] (2) Deposition of nanoparticles

[0037] The plasma-treated carbon nanotube film was fixed on the magnetron sputtering sample stage, and the sample chamber was evacuated to a pressure of 10. -4 After Pa, the sample is sent into the target cavity. Because high-purity Cu has good conductivity, a DC target cavity is used. The sample stage temperature is raised to 300℃, the target ignition power is set to 15W, the sample stage rotation speed is set to 10rad / min, the coating power is set to 10W, the pre-coating time is set to 300s, the coating time is set to 150s, and the argon pressure is set to 1.33Pa.

[0038] (3) Structural characterization of composite thin films

[0039] The composite film prepared in step (2) was placed in a 15ml glass bottle, 3mL of ethanol was added, and the mixture was sonicated for 20min. Then, 3-7 drops were placed on the carbon microgrid using a 10μL pipette. After drying, the film was observed under a transmission electron microscope. Figure 2 The diameter distribution of Cu particles is 5–7 nm. Figure 3The Cu nanoparticles are uniformly distributed on the walls of single-walled carbon nanotubes, resulting in high-density, small-sized Cu nanoparticles with a density of 1.0 × 10⁻⁶ per square micrometer. 5 A Cu particle.

[0040] (4) Electrocatalytic CO2 reduction performance test of composite film

[0041] The CO2 reduction activity of the catalyst was tested in an acidic electrolyzer with a CO2-saturated 0.5 mol / L KHCO3 electrolyte. The maximum Faraday efficiency of 90% was achieved at -0.9 V.

[0042] Example 2

[0043] In this embodiment, a composite film of single-walled carbon nanotubes embedded with Pt nanoparticles was prepared by creating defects through acid treatment. The specific experimental steps are as follows:

[0044] (1) Defect introduction

[0045] Add 180 mL of 98 wt% concentrated sulfuric acid and 60 mL of 68 wt% concentrated nitric acid to a beaker, mix well, transfer the carbon nanotube film onto a polytetrafluoroethylene scaffold, immerse in the mixed acid solution for 48 h, and obtain a defective single-walled carbon nanotube film.

[0046] (2) Deposition of nanoparticles

[0047] Because high-purity Pt has good conductivity, a DC target cavity is used, and the process is the same as step (2) in Example 1, except that the temperature is 300℃, the coating power is 5W, and the coating time is 75s.

[0048] (3) Structural characterization of composite thin films

[0049] Same as step (3) in Example 1, after drying, observe in a transmission electron microscope. Figure 4 The diameter distribution of Pt particles is 0.5–1.0 nm. Figure 5 Furthermore, by embedding these particles within the walls of single-walled carbon nanotubes, high-density, small-sized Pt nanoparticles were obtained, with a density of 6.0 × 10⁻⁶ per square micrometer. 5 Pt particles.

[0050] (4) Electrocatalytic hydrogen evolution performance test of composite film

[0051] The composite film obtained in step (3) was fixed with an electrode clamp, and the reaction area was cut to 5 mm × 5 mm. A linear scan was performed at a scan rate of 0.005 V / s in a three-electrode electrochemical workstation (working electrode: composite film clamped by electrode clamp; counter electrode: graphite electrode; reference electrode: Ag / AgCl electrode; electrolyte solution: 1 mol / L KOH solution). The electrocatalytic hydrogen evolution performance of the composite film was measured to be within 10 mA / cm². 2The overpotential at the current density is 68mV.

[0052] like Figure 6 As shown, the linear voltammetric curves for the electrocatalytic hydrogen evolution of small-sized Pt nanoparticle / single-walled carbon nanotube composite films are obtained from... Figure 6 It can be seen that at 10mA / cm 2 The overpotential at current density is 38mV, outperforming commercial 20% Pt / C.

[0053] Example 3

[0054] In this embodiment, an acid treatment method was used to create defects and prepare a graphene-embedded Au nanoparticle composite film. The specific experimental steps are as follows:

[0055] (1) Defect introduction

[0056] Same as step (1) in Example 2, except that: 150 ml of 98 wt% concentrated sulfuric acid and 90 ml of 68 wt% concentrated nitric acid are mixed evenly, and the graphene film is transferred to a polytetrafluoroethylene support and placed in the mixed acid solution for 48 hours to obtain a defective graphene film.

[0057] (2) Deposition of nanoparticles

[0058] The graphene film obtained in step (1) is fixed on the sample stage of magnetron sputtering. Since the Au target material has good conductivity, a DC target cavity is used. The same as step (2) in Example 1, except that the temperature is 500℃, the coating power is 10W, and the coating time is 300s.

[0059] (3) Structural characterization of composite thin films

[0060] Following the same steps (3) as in Example 1, after drying, the Au particles were observed in a transmission electron microscope. The diameter distribution of the Au particles was 1–3 nm, and they were uniformly distributed on the graphene.

[0061] (4) Test of water evaporation performance of photothermal interface of composite film

[0062] The Au nanoparticle / graphene film obtained in step (3) was used for seawater desalination by interfacial water evaporation. The plasmon effect of the gold nanoparticles significantly improved the photothermal conversion efficiency of the composite film, achieving an evaporation efficiency of 2.60 kg / m³. 2 h.

[0063] Example 4

[0064] In this embodiment, a composite film of carbon nanofibers embedded with Ni nanoparticles is prepared. The specific experimental steps are as follows:

[0065] (1) Defect introduction

[0066] Same as step (1) in Example 1, except that a carbon monoxide plasma with a power of 20W is used and the processing time is 60s.

[0067] (2) Deposition of nanoparticles

[0068] The carbon nanofiber film obtained in step (1) was fixed on the sample stage of magnetron sputtering. Nickel was sputtered using a strong magnetic target at a temperature of 200°C, a coating power of 30W, and a coating time of 100s.

[0069] (3) Structural characterization of composite thin films

[0070] Following the same procedure as in Example 1 (3), after drying, the particles were observed under a transmission electron microscope. The diameter distribution of the Ni particles was 3–4 nm, and they were embedded in the carbon nanofibers, resulting in high-density, small-sized Ni nanoparticles with a density of 1.5 × 10⁻⁶ per square micrometer. 4 Ni particles.

[0071] (4) Electrocatalytic hydrogen evolution performance test of composite film

[0072] The composite film obtained in step (3) was directly used as the working electrode, in the same manner as step (4) of Example 2. The electrocatalytic hydrogen evolution efficiency of the composite film was measured to be 10 mA / cm. 2 The overpotential at the current density is 128mV.

[0073] Example 5

[0074] In this embodiment, a Pt composite film with adjustable size single-walled carbon nanotubes is prepared by changing the defect manufacturing conditions. The specific steps are as follows:

[0075] (1) Defect introduction

[0076] Similar to step (1) in Example 1, except that argon plasma is used, with power of 40W and 50W respectively, and all are processed for 1500s to obtain samples with different defect levels.

[0077] (2) Deposition of nanoparticles

[0078] The same as step (2) in Example 1, except that the temperature is 400℃, the coating power is 5W, and the coating time is 100s.

[0079] (3) Structural characterization of composite thin films

[0080] Similar to step (3) in Example 1, when the plasma power is 40W, the diameter distribution of Pt particles is 1-2nm, and when the plasma power is 50W, the diameter distribution of Pt particles is 0.5-1nm, and they are embedded in the wall of single-walled carbon nanotubes, thus obtaining high-density, small-sized Pt nanoparticles with a density of 6.5 × 10⁻⁶ per square micrometer. 4 A Cu particle.

[0081] (4) Electrocatalytic hydrogen evolution performance test of composite film

[0082] Same as step (4) in Example 2, the plasma 40W composite thin film electrocatalytic hydrogen evolution is 10 mA / cm 2 The overpotential at current density is 68 mV; the plasma 50W composite thin film electrocatalytic hydrogen evolution is 10 mA / cm². 2 The overpotential at current density is 55mV

[0083] Example 6

[0084] In this embodiment, a Pt composite film with tunable size single-walled carbon nanotubes is prepared by changing the magnetron sputtering conditions. The specific steps are as follows:

[0085] (1) Defect introduction

[0086] Similar to step (1) in Example 1, except that the air plasma power is 10W and the processing time is 100s.

[0087] (2) Deposition of nanoparticles

[0088] Similar to step (2) in Example 1, except that the sample stage temperature is 600℃, the coating power is 20W, and the coating time is 10s and 30s.

[0089] (3) Structural characterization of composite thin films

[0090] Same as step (3) in Example 1, after drying, observe in a transmission electron microscope. When the sputtering time is 150s, the diameter distribution of Pt particles is 3-5nm. When the sputtering time is 300s, the diameter distribution of Pt particles is 5-7nm and they are embedded in the wall of single-walled carbon nanotubes.

[0091] (4) Electrocatalytic hydrogen evolution performance test of composite film

[0092] Similar to step (4) in Example 2, when the sputtering time is 150 s, the electrocatalytic hydrogen evolution of the composite thin film is 10 mA / cm. 2 The overpotential at the current density is 107 mV; when the sputtering time is 300 s, the electrocatalytic hydrogen evolution of the composite thin film is 10 mA / cm². 2 The overpotential at the current density is 81mV.

[0093] Comparative Example 1

[0094] The specific steps for preparing Cu nanoparticle / single-walled carbon nanotube composite films by magnetron sputtering are as follows:

[0095] (1) Deposition of nanoparticles

[0096] Same as step (2) in Example 1.

[0097] (2) Structural characterization of composite thin films

[0098] Same as step (3) in Example 1, but transmission electron microscopy shows that the nanoparticles have a wide size distribution and are supported on the walls of highly crystalline carbon nanotubes.

[0099] (3) Electrocatalytic carbon dioxide reduction performance test of composite film

[0100] The test was conducted under the same conditions as in step (4) of Example 1. At -0.9V, the maximum Faraday efficiency of CO was only 40%.

[0101] The results of the examples and comparative examples show that the metal nanoparticles prepared by defect-induced deposition have smaller size and higher density. The biggest feature of this invention compared with the prior art is that the defects in the carbon nanomaterials cause metal particles to adsorb and anchor at the defects, nucleating and growing to form metal clusters / nanoparticles, thus obtaining a composite film in which monodisperse metal nanoparticles are embedded in the carbon nanomaterials. The metal nanoparticles of different compositions prepared by this method are embedded in the carbon nanofilm, which have a stronger interaction between the metal particles and the carbon nanocarrier, and have broad application prospects in energy storage and conversion, sensing and monitoring, catalysis and other fields.

[0102] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A method for defect-induced synthesis of a nanocarbon material-embedded metal nanoparticle composite thin film, characterized by, Defects are introduced into nano-carbon material films using plasma etching or chemical oxidation. Different metal targets are then bombarded with magnetron sputtering under heating conditions to nucleate and grow metal clusters / nanoparticles at the defects, thus obtaining a composite film of nano-carbon material with embedded metal nanoparticles. By controlling the defects in the nano-carbon material film and the magnetron sputtering process conditions, metal nanoparticles with adjustable density, size, and dispersion can be obtained, with their size precisely adjustable in the sub-nanometer to ten-nanometer range. By bombarding different metal targets with magnetron sputtering and controlling the sputtering power and heating temperature during the magnetron sputtering process, metal particles are preferentially adsorbed at the defect sites, and after anchoring, metal clusters / nanoparticles are nucleated and grown to obtain a composite film of metal nanoparticles embedded in nano-carbon materials. Heating is required during magnetron sputtering. The heating temperature is controlled within the range of 100~900 ℃ to stabilize the metal nanoparticles and embed them into the defects. High-density defects were created by treating high-quality single-walled carbon nanotube films with 30-50 W hydrogen plasma for 1000-1500 s. During magnetron sputtering, the heating temperature was controlled at 100-400 ℃, the sputtering power was controlled at 0.5-50 W, and the sputtering time of high-purity platinum target was 5-100 s, thus obtaining a composite film of single-walled carbon nanotubes embedded with high-density sub-nanometer platinum clusters.

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