Method for regulating and controlling catalytic performance of single-walled carbon nanotube confinement metal catalyst

Abstract

The invention provides a method for regulating and controlling the catalytic performance of a single-walled carbon nanotube confinement metal catalyst. The regulating and controlling method comprises the following steps: filling a single-walled carbon nanotube with metal; and the catalytic performance is regulated and controlled through a metal structure regulation and control mode of changing the metal amount and / or the metal particle size. According to the single-walled carbon nanotube metal confinement catalyst, the performance of the catalyst is regulated and controlled in a metal structure regulation and control mode of changing the metal amount and / or the metal particle size, so that the catalyst can be used in different application scenes.

Description

Technical Field

[0001] The present invention specifically relates to a method for regulating the catalytic performance of a single-walled carbon nanotube confined metal catalyst. Background Art

[0002] At present, metal catalysts include platinum catalysts, palladium catalysts, silver catalysts, etc. Among them, platinum catalysts are an important type of catalyst in the energy field and have been widely used in sustainable energy systems such as fuel cells and water decomposition to produce hydrogen. In particular, carbon-supported platinum (Pt / C) catalysts are regarded as one of the ideal catalyst materials and are also one of the important catalyst materials in current commercial applications.

[0003] Carbon nanomaterials include carbon nanotubes, graphene, C60, etc., among which carbon nanotubes are widely used. Researchers have found that the catalytic performance can be improved by loading metals (e.g., Pt / C catalysts) on carbon nanotubes. In addition, the performance of the catalyst can be improved by confining metals within carbon nanotubes (literature "Amperometric sensor for the detection of hydrogen stable isotopes based on Pt nanoparticles confined within single-walled carbon nanotubes (SWNTs)").

[0004] Currently, confining metals in carbon nanotubes is usually achieved by filling them. However, there is no method for regulating the confined metals in carbon nanotubes to obtain better catalytic performance. Summary of the invention

[0005] The present invention aims to provide a method for regulating the catalytic performance of a single-walled carbon nanotube confined metal catalyst, as there is currently no method for regulating the catalytic performance by regulating the confined metal in the carbon nanotube.

[0006] The technical method of the present invention is as follows:

[0007] A method for regulating the catalytic performance of a single-walled carbon nanotube confined metal catalyst comprises: filling metal in the single-walled carbon nanotube; and regulating the catalytic performance by changing the metal amount and / or the metal structure regulation mode of the metal particle size.

[0008] Optionally, the filling step includes: S1, filling a metal element melt, a solution containing a metal element, or a gaseous metal precursor into a single-walled carbon nanotube to obtain a filler; S2, processing the filler of step S1 to convert the metal element in the filler into a metal; wherein, a method of changing the amount of metal includes: controlling the amount of the metal element melt, the solution containing a metal element, or the gaseous metal precursor entering the single-walled carbon nanotube in step S1, and / or controlling the amount of metal converted into the filler during the treatment process in step S2; a method of changing the metal particle size includes: controlling the particle size of the metal in the carbon nanotube after treatment to be within any range of 0.05 to 1000 nm.

[0009] Optionally, the particle size of the metal is smaller than the length of the single-walled carbon nanotube.

[0010] Optionally, after the control treatment, the particle size of the metal in the carbon nanotubes is in any range of 0.05 to 50 nm.

[0011] Optionally, the metal is a metal in the periodic table of chemical elements.

[0012] Optionally, the metal includes one or more of gold, silver, platinum, copper, iron, cobalt, nickel, palladium, rhodium, ruthenium, tin, and titanium.

[0013] Optionally, the mass ratio of the single-walled carbon nanotube to the metal element melt is 1:1 to 15000.

[0014] Optionally, the ratio of the single-walled carbon nanotube to the solution containing the metal element is 100 mg: 0.01-20 M.

[0015] The beneficial effects of the present invention are:

[0016] (1) The single-walled carbon nanotube-confined metal catalyst of the present invention regulates the catalyst performance by changing the metal amount and / or the metal particle size of the metal structure regulation method, so that it can be used in different application scenarios.

[0017] (2) The present invention obtains single-walled carbon nanotube confined metal catalysts with different contents by changing the amount of metal filled in the single-walled carbon nanotubes, thereby obtaining catalysts with different activation areas. Researchers select catalysts with different particle sizes and activation areas according to different application scenarios.

[0018] (3) The present invention obtains single-atom, diatomic, and polyatomic catalysts by changing the particle size of the treated metal, thereby obtaining catalysts with different activation areas. Researchers select catalysts with different atoms and activation areas according to different application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1HRTEM image of the carbon nanotube confined platinum catalyst of Example 1a of the present invention;

[0020] Figure 2 This is a length distribution diagram of the carbon nanotube confined platinum catalyst of a in Example 1 of the present invention;

[0021] Figure 3 This is a HRTEM image of the carbon nanotube confined platinum catalyst of Example 1b of the present invention;

[0022] Figure 4 This is a length distribution diagram of the carbon nanotube confined platinum catalyst in Example 1b of the present invention;

[0023] Figure 5 This is a HRTEM image of the carbon nanotube-confined platinum catalyst c in Example 1 of the present invention;

[0024] Figure 6 This is a length distribution diagram of the carbon nanotube confined platinum catalyst c in Example 1 of the present invention;

[0025] Figure 7 The cyclic voltammetry curves of carbon nanotube confined platinum catalysts a, b, and c in Example 1 of the present invention are shown. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The present invention provides a method for regulating the catalytic performance of a single-walled carbon nanotube confined metal catalyst, the method comprising: filling metal in the single-walled carbon nanotube; and regulating the catalytic performance by changing the metal structure regulation mode of changing the metal amount and / or metal particle size.

[0028] In the present invention, the filling step includes: S1, filling a metal element melt, a solution containing a metal element, or a gas phase metal precursor into a single-walled carbon nanotube to obtain a filler; S2, processing the filler of step S1 to convert the metal element in the filler into a metal.

[0029] Furthermore, the metal is a metal in the periodic table of chemical elements. For example, the metal includes one or more of gold, silver, platinum, copper, iron, cobalt, nickel, palladium, rhodium, ruthenium, tin, and titanium.

[0030] Here, the solution containing the metal element may include any one of a metal compound solution and a metal halogen solution.

[0031] Here, the metal precursor of the metal element melt may be an anhydrous metal chloride. For example, ruthenium chloride. Specifically, the filling step includes: melting the metal precursor under vacuum conditions or inert gas to fill it into the single-walled carbon nanotube. Here, the melting temperature is determined according to the physicochemical properties of different metal precursors.

[0032] Here, the metal precursor of the gas phase metal precursor includes metal chloride or metal organic. Here, the metal organic can be acetylacetonate metal. For example, platinum acetylacetonate. Metal chlorides are such as titanium chloride. Filling includes: placing the metal precursor in a heating furnace under vacuum conditions or inert gas to sublimate so as to fill it into the single-walled carbon nanotube. Here, the sublimation temperature is determined according to the physicochemical properties of different metal precursors.

[0033] In one embodiment, the method of changing the amount of metal includes: controlling the amount of metal element melt, solution containing metal element, and gas phase metal precursor entering the single-walled carbon nanotube in step S1. For example, the ratio of single-walled carbon nanotube and solution containing metal element is 100mg: 0.01~20M. The present invention optimizes the performance of the catalyst by adjusting the concentration of the solution to ensure that the metal is filled into the single-walled carbon nanotube, and the filling amount of the metal will not be too much, which will affect the catalytic performance of the catalyst. For example, the ratio is 100mg: 0.5M, 100mg: 2M, 100mg: 7M, 100mg: 10M, 100mg: 15M. For another example, the mass ratio of single-walled carbon nanotube to metal element melt is 1: 1~15000. For example, the mass ratio is 1:100, 1:500, 1:2000, 1:3000, 1:5000, 1:8000, 1:10000, 1:13000.

[0034] In one embodiment, the method of changing the amount of metal further includes: controlling the amount of metal transformed by the filler during the treatment process in step S2. Specifically, the filler contains a metal element melt, a solution containing a metal element, and a gas phase metal precursor, and the filler containing the metal element treats different amounts of metal by different treatment temperatures, times, and methods.

[0035] Here, the treatment is carried out by hydrogen reduction, thermal degradation or reducing agent. Here, the temperature of hydrogen reduction and thermal degradation is determined according to the physicochemical properties of the metal precursor. The reducing agent can be sodium borohydride (NaBH4).

[0036] In one embodiment, the method of changing the metal particle size includes: controlling the particle size of the treated metal in the carbon nanotube to be within any range of 0.05 to 1000 nm. Here, according to the needs of the researcher, the particle size of the treated metal is regulated, and the regulated particle size range is 0.05 to 1000 nm. For example, the particle size of the metal is 0.05 to 1 nm, 0.05 to 2 nm, 0.05 to 3 nm, 0.05 to 5 nm, 0.3 to 6 nm, 1 to 10 nm, 2 to 15 nm, 3 to 20 nm, 3 to 30 nm, 4 to 40 nm, 5 to 50 nm, 10 to 70 nm, 16 to 100 nm, 20 to 150 nm. Preferably, the particle size of the metal is in the range of 0.05 to 50 nm.

[0037] In one embodiment, the metal particle size is smaller than the diameter of the single-walled carbon nanotube, ensuring that the metal (active sites) in the catalyst can be exposed to the solution during catalysis using the solution, thereby making the catalyst have good catalytic performance.

[0038] In one embodiment, the present invention provides a liquid phase filling embodiment of single-walled carbon nanotubes and a solution containing metal elements to adjust the catalytic performance of the catalyst. Similarly, the above-mentioned method can also be used to adjust the amount of metal element melt and gas phase metal precursor filling single-walled carbon nanotubes to adjust the catalytic performance of the catalyst.

[0039] Here, a method for regulating the catalytic performance of single-walled carbon nanotube-confined platinum catalysts is presented.

[0040] C1. Mix, stir and ultrasonicate single-walled carbon nanotubes and tetraammine platinum chloride solutions of different concentrations. The mixing time is 0.5 to 24 hours. The stirring time is 0.05 to 24 hours. The ultrasonication time is 0.001 to 14 hours.

[0041] C2. Filter, dry and reduce the filler to obtain powder. Filter to separate the solid and liquid of the mixture and take out the solid. Drying can be performed by vacuum drying. The reduction temperature is 100 to 700°C and the reduction time is 0.01 to 24 hours.

[0042] For example, the mixing time is 2-20h, 3-10h, 5-15h, 10-21h. The stirring time is 2-20h, 3-10h, 5-15h, 10-20h. The ultrasonic time is 0.002-8h, 0.01-10h, 2-12h, 3-13h, 4-14h. The reduction temperature is 200°C, 300°C, 400°C, 500°C, 600°C. The reduction time is 0.02-4h, 2-20h, 3-10h, 5-15h, 10-21h.

[0043] Preferably, the particle size of the metal is smaller than the length of the single-walled carbon nanotube, ensuring that the metal particle size can be confined within the single-walled carbon nanotube.

[0044] The present invention is described in detail below by way of examples and experimental examples, but these are merely examples and do not limit the present invention in any form.

[0045] Example 1

[0046] This embodiment provides a method for regulating the catalytic performance of a single-walled carbon nanotube confined metal catalyst, comprising:

[0047] (1) 100 mg of single-walled carbon nanotubes were mixed with (a) 0.1 M Pt(NH3)4Cl2, (b) 0.3 M Pt(NH3)4Cl2, and (c) 0.5 M Pt(NH3)4Cl2 aqueous solutions for 1 h, ultrasonicated for 6 h, and stirred for 12 h for liquid phase filling;

[0048] (2) then filtering, vacuum drying, and grinding into powder;

[0049] (3) The powder was reduced under hydrogen at 200°C for 1 hour to obtain a catalyst. 100 mg of single-walled carbon nanotubes were respectively reacted with (a) 0.1 M Pt(NH3)4Cl2 to prepare the catalyst. Figure 1 and Figure 2 100 mg of single-walled carbon nanotubes were reacted with (a) 0.3 MPt (NH3) 4 Cl2 to prepare the catalyst. Figure 3 and Figure 4 100 mg of single-walled carbon nanotubes were respectively mixed with (c) 0.5 M Pt(NH3)4Cl2 to prepare the catalyst as shown in FIG. Figure 5 and Figure 6 Here, Figure 2 , Figure 4 and Figure 6 They were obtained by counting 100 nanoparticles in the HRTEM images of the corresponding catalysts. Figure 1 and Figure 2 As shown, it shows that the nanoparticles in the Pt@SWNT_1 (a) composite are sparsely distributed. The axial length of most particles is distributed between 2-3nm, with an average length of 2.5nm. Figure 3 and Figure 4 As shown in Figure 2, the nanoparticles from Pt@SWNT_2 (b) are significantly longer than those from Pt@SWNT_1, with an average length of 4.1 nm and most of the sizes distributed in the range of 2-4 nm. Figure 5 and Figure 6 As shown, nanoparticles with longer axial length appear in Pt@SWNT_3(c), with an average length of 7.3nm. Figure 1-Figure 3As shown, the HRTEM results show that the particles of Pt@SWNT_1 are shorter and the most sparsely distributed, the particles of Pt@SWNT_2 are of moderate length and the most densely distributed, and the particles of Pt@SWNT_3 are the longest.

[0050] Figure 7 The cyclic voltammetry curves of commercial Pt / C, a, b, and c in Example 1 were obtained at a scan rate of 50 mV / s in 0.5 M H2SO4. The electrochemical active area resolution of different carbon nanotube confined platinum catalysts was calculated as follows: 381 cm for a in Example 1 2 / mg, 742cm of b in Example 1 2 / mg, 476cm of c in Example 1 2 / mg, 95cm of commercial Pt / C catalyst 2 / mg. It can be seen that the electrochemical active areas of carbon nanotube-confined platinum catalysts with different structures are different. The activation area of ​​the catalyst of the present invention is much higher than that of the commercial Pt / C catalyst, so it can provide a higher reaction rate and ultimately be applied in different scenarios.

[0051] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention, and the protective measures required for the experiments should comply with relevant environmental protection and safety requirements. Based on the embodiments of the present invention and the protective measures required for the corresponding experiments, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for regulating the catalytic performance of a single-walled carbon nanotube confined metal catalyst, characterized in that: The control method comprises: Filling metal into single-walled carbon nanotubes; regulating catalytic performance by changing the metal amount and / or metal particle size.

2. The control method according to claim 1, characterized in that: The filling steps include: S1, filling a metal element melt, a solution containing a metal element, or a gas phase metal precursor into a single-walled carbon nanotube to obtain a filler; S2, processing the filler of step S1 to convert the metal elements in the filler into metal; wherein, The method of changing the amount of metal includes: controlling the amount of metal element melt, solution containing metal element, and gas phase metal precursor entering the single-walled carbon nanotube in step S1, and / or controlling the amount of metal converted by the filler during the treatment process in step S2; The method of changing the metal particle size includes: controlling the particle size of the metal in the carbon nanotube after treatment to be within any range of 0.05 to 1000 nm.

3. The control method according to claim 1, characterized in that: The particle size of the metal is smaller than the length of the single-walled carbon nanotube.

4. The control method according to claim 1, characterized in that: After the control treatment, the particle size of the metal in the carbon nanotube is in any range of 0.05 to 50 nm.

5. The control method according to any one of claim 1, characterized in that: The metal is a metal in the periodic table of chemical elements.

6. The control method according to claim 5, characterized in that: The metal includes one or more of gold, silver, platinum, copper, iron, cobalt, nickel, palladium, rhodium, ruthenium, tin, and titanium.

7. The control method according to any one of claim 2, characterized in that: The mass ratio of the single-walled carbon nanotube to the metal element melt is 1:1-15000.

8. The control method according to any one of claim 2, characterized in that: The ratio of the single-walled carbon nanotube to the solution containing the metal element is 100 mg: 0.01-20 M.

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