Platinum monatomic transition metal alloy embedded carbon nanotube, preparation method and application

Abstract

The invention discloses a platinum monatomic transition metal alloy embedded carbon nano tube, a preparation method and application, and the carbon nano tube comprises a carbon nano tube with an opening defect characteristic; the inner cavity of the carbon nano tube is filled with the transition metal, and the platinum atoms are dispersed in the inner cavity of the carbon nano tube in a monatomic form. According to the invention, the one-dimensional confinement effect of the carbon nanotubes is fully utilized, and the metal platinum is in atomic-scale dispersion, so that the sites of the active center of the catalytic material are increased, and the stable improvement of the catalytic activity is realized. And meanwhile, the industrial problems of solubility resistance and easy agglomeration of the monatomic alloy under extreme conditions are solved, so that the catalytic activity and durability of the monatomic platinum catalyst under the extreme conditions are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the field of catalytic technology, and particularly relates to a carbon nanotube embedded with platinum single-atom transition metal alloy, a preparation method and an application thereof. Background Art

[0002] Developing and utilizing clean and renewable energy is a key strategy for solving energy and environmental problems. The hydrogen-oxygen fuel cell using hydrogen as fuel has many advantages over traditional heat engine power plants. Promoting the energy conversion efficiency depends on highly efficient electrocatalysts, and various reaction mechanisms have been studied based on metal catalysts in the past few decades. As an emerging clean energy technology, although the fuel cell has many advantages, it also faces some problems and challenges, mainly including the relatively high cost of noble metal catalysts, which are prone to corrosion, poisoning and deactivation during long-term operation, thus affecting the performance and stability of the battery.

[0003] Therefore, in view of the above technical problems, it is necessary to provide a carbon nanotube embedded with platinum single-atom transition metal alloy, a preparation method and an application thereof.

[0004] The information disclosed in this background art section is only intended to enhance the overall understanding of the present invention and should not be regarded as an admission or any form of implication that this information constitutes prior art already known to those of ordinary skill in the art. Summary of the Invention

[0005] The object of the present invention is to provide a carbon nanotube embedded with platinum single-atom transition metal alloy, a preparation method and an application thereof.

[0006] In order to achieve the above object, the technical solution provided by a specific embodiment of the present invention is as follows:

[0007] The carbon nanotube embedded with platinum single-atom transition metal alloy includes

[0008] a carbon nanotube having an opening defect feature;

[0009] a transition metal filled in the internal cavity of the carbon nanotube, and platinum atoms dispersed in the internal cavity of the carbon nanotube in a single-atom form.

[0010] In one or more embodiments of the present invention, the filling mass ratio of the transition metal M in the carbon nanotube is 10%-50%.

[0011] In one or more embodiments of the present invention, the filling amount of the transition metal in the carbon nanotube is such that the atomic ratio: C:M = 95:1 - 95:4.

[0012] In one or more embodiments of the present invention, the filling amount of platinum atoms in the carbon nanotubes is such that the atomic ratio: C:Pt = 95:4 - 95:1. Preferably, M:Pt = 4:1 - 1:4.

[0013] In one or more embodiments of the present invention, the carbon nanotubes are selected from: single-walled carbon nanotubes, multi-walled carbon nanotubes.

[0014] In one or more embodiments of the present invention, the transition metal M is selected from cobalt, nickel, copper, molybdenum.

[0015] In one or more embodiments of the present invention, a method for preparing a platinum single-atom transition metal alloy embedded carbon nanotube includes:

[0016] Preparing carbon nanotubes with open defect characteristics;

[0017] Filling a transition metal in the carbon nanotubes: After mixing the transition metal source with the nanotubes, high-temperature filling is carried out under vacuum conditions, and after the first purification and the first annealing, the first carbon nanotube filled with the transition metal is obtained;

[0018] Incorporating platinum single atoms into the first carbon nanotube: The first carbon atoms are fully mixed and filled in a solution dispersed with chloroplatinic acid, and then the target product is obtained after the second purification and the second annealing. Preferably, the first purification and / or the second purification includes washing with deionized water.

[0019] In one or more embodiments of the present invention, the first annealing is to anneal at a temperature of 300 - 500 °C for 2 - 4 hours in a hydrogen-argon atmosphere and then cool. Further, in the hydrogen-argon atmosphere, H2:Ar = (2:8) - (5:5).

[0020] In one or more embodiments of the present invention, the high-temperature filling is to heat at a temperature of 1000 - 1100 °C for 2 - 4 days.

[0021] In one or more embodiments of the present invention, the vacuum condition is satisfied: 10 -3 -10 -4 Pa.

[0022] In one or more embodiments of the present invention, the second annealing is to anneal at a temperature of 300 - 600 °C for 2 - 4 hours in a hydrogen-argon atmosphere and then cool. Further, in the hydrogen-argon atmosphere, H2:Ar = (2:8) - (5:5), and this is the volume ratio.

[0023] In one or more embodiments of the present invention, the transition metal source is selected from: chlorides, carbonates of transition metals.

[0024] In one or more embodiments of the present invention, the mixed filling is carried out under stirring. Further preferably, the stirring condition is to stir at a rotation speed of 200 - 1000 rpm for 1 - 12 h.

[0025] In one or more embodiments of the present invention, the application of platinum single-atom transition metal alloy embedded carbon nanotubes in redox catalytic reactions.

[0026] Compared with the prior art, the platinum single-atom transition metal alloy embedded carbon nanotubes, preparation method and application of the present invention react with platinum source, transition metal compound and carbon nanotubes as raw materials, so that platinum and transition metal compounds enter the carbon nanotubes to form platinum single-atom alloy embedded carbon nanotubes. Due to the one-dimensional confinement effect of carbon nanotubes and the atomic dispersion of metallic platinum, it is beneficial to improve the selective activity of oxygen reduction to hydrogen peroxide or hydroxide ions. By further regulating the composition to optimize the electronic structure of the catalyst, the catalytic activity and stability can be improved.

[0027] The present invention will utilize the one-dimensional confinement effect of carbon nanotubes to synthesize platinum single-atom alloy with high atomic utilization rate in carbon nanotubes. By using the confinement effect of this nano-scale inner cavity, the single-atom alloy can be stably confined in the tube cavity, and the particle size of the alloy can be further reduced from the micron scale to the nano scale, thereby changing the structure and proportion of the active centers of the catalytic material. At the same time, the protective effect of carbon nanotubes on platinum single-atom alloy can significantly improve the catalytic performance of the catalyst under extreme conditions and its anti-dissolution property during long-term cycling.

[0028] The one-dimensional confinement effect of carbon nanotubes can arrange platinum single-atom alloy in an orderly manner inside the carbon nanotubes, and metallic platinum shows atomic dispersion, thereby increasing the sites of the active centers of the catalytic material and achieving a stable improvement in catalytic activity. At the same time, it solves the industrial problems of the anti-dissolution property and easy agglomeration of single-atom alloy under extreme conditions, and further significantly improves the catalytic activity and durability of single-atom platinum catalyst under extreme conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0030] Figure 1 It is the schematic diagram and state diagram of preparing single-atom platinum-nickel alloy embedded carbon tube in an embodiment of the present invention;

[0031] Figure 2 It is the thermogravimetric curve of nickel chloride embedded carbon tube in an embodiment of the present invention;

[0032] Figure 3STEM image of single-atom platinum-nickel alloy embedded carbon nanotubes in an embodiment of the present invention;

[0033] Figure 4 Test result graph of oxygen reduction performance of single-atom platinum-nickel alloy embedded carbon nanotubes in an embodiment of the present invention;

[0034] Figure 5 Test result graph of the stability of single-atom platinum-nickel alloy embedded carbon nanotubes in an embodiment of the present invention;

[0035] Figure 6 Oxygen reduction performance result graph before and after the stability test of single-atom platinum-nickel alloy embedded carbon nanotubes in an embodiment of the present invention;

[0036] Figure 7 XPS image of single-atom platinum-nickel alloy embedded carbon nanotubes in an embodiment of the present invention. Detailed implementation mode

[0037] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0038] It is well known to those skilled in the art that by forming an alloy catalyst of multiple metals, the electron effect, cluster effect, synergistic effect, etc. make the performance of the alloy catalyst superior to that of a single-metal catalyst. However, only the surface metal atoms of the alloy participate in the reaction, and most of them are noble metals. Therefore, it is necessary to improve the utilization rate of noble metals to reduce the catalyst cost. And single-atom catalysts have 100% atomic utilization rate and exhibit some properties different from single-metal catalysts. The technical solution of the present invention combines the advantages of alloy catalysts and single-atom catalysts by optimizing the preparation process, enabling one metal atom in the alloy to be dispersed at the atomic level on the surface of another metal, thereby forming a single-atom alloy, and optimizing the catalytic performance and cost simultaneously through the adjustment of the structure and composition.

[0039] The specific solution can be as follows:

[0040] S1. Pretreatment of carbon nanotubes

[0041] Weigh 100 mg of Tuball single-walled carbon nanotube powder with a tube diameter less than or equal to 2 nm and place it in a quartz boat, then put it into a tube furnace and anneal it in an air atmosphere at 500-600 °C for 1-4 h to obtain open Tuball single-walled carbon nanotubes.

[0042] S2. Filling of Transition Metals in Carbon Nanotubes

[0043] First, 20 - 40 mg of the above carbon nanotubes are fully mixed with 100 mg of transition metal chloride powder to obtain a transition metal precursor. 80 - 120 mg of the transition metal precursor is sealed in a quartz tube under a vacuum of 10 -3 -10 -4 Pa, and then heated and held for 3 days in a tube furnace at a temperature higher than the melting point of the transition metal compound. After annealing, the black powder is taken out and further washed with deionized water, ultrasonically cleaned, and centrifuged to collect and remove the residual precursors outside the CNT. Finally, the black powder is annealed in a hydrogen - argon atmosphere for 2 hours and then gradually cooled to room temperature. The transition metal - filled carbon nanotubes M@SWCNT are obtained.

[0044] S3. Synthesis of Platinum Single - Atom Alloy in Carbon Nanotubes

[0045] Prepare a chloroplatinic acid solution and place it in a sample bottle. Take 2 mg - 30 mg of the above M@SWCNT and place it in 20 mL of 0.001 - 0.5 M chloroplatinic acid solution, and add a magnetic stirrer bar. Seal the sample bottle and stir at room temperature on a magnetic stirrer at a speed of 200 - 2000 rpm for 1 - 12 h. After taking out the magnetic stirrer bar, pour the mixture into a centrifuge tube, and centrifuge the mixture at a speed of 8000 rpm for 30 min using a high - speed centrifuge, and pour off the supernatant. Add 10 - 100 mL of deionized water to mix evenly with the black precipitate at the bottom layer, add a magnetic stirrer bar, and stir at a speed of 200 - 1000 rpm for 1 - 10 min. Then take out the magnetic stirrer bar and centrifuge at a speed of 8000 - 10000 rpm for 10 - 30 min to wash the chloroplatinic acid on the outer wall of the carbon tube. Repeat the washing until the filtrate is colorless. Finally, place the precipitate in a vacuum oven at 60 - 150 °C and dry overnight. Anneal the dried black powder sample in a hydrogen - argon mixed atmosphere to obtain single - wall carbon nanotubes embedded with platinum single - atom alloy.

[0046] The features and properties of the present invention are further described in detail below in conjunction with the embodiments.

[0047] Including but not limited to the following embodiments, the pretreated carbon nanotubes are all: Weigh 100 mg of Tuball single - wall carbon nanotube powder with a diameter less than or equal to 2 nm and place it in a quartz boat, then put it into a tube furnace and anneal it for 1 h in an air atmosphere at 500 °C to obtain open Tuball single - wall carbon nanotubes.

[0048] Example 1

[0049] This example provides a method for preparing single - atom platinum - nickel alloy - embedded carbon nanotubes, including the following steps:

[0050] (1) Filling of nickel in carbon nanotubes: At room temperature, 100 mg of anhydrous nickel chloride (NiCl2) and 30 mg of the above-mentioned pretreated single-walled carbon nanotubes were sealed together in a quartz tube under a vacuum of 10 -3 Pa, and then heated in a tube furnace at a temperature of 1000 °C for 2 days. After annealing, the black powder was taken out and further washed with deionized water, and ultrasonic cleaning and centrifugation were used to remove the residual precursors outside the CNT. Finally, the black powder was annealed at a temperature of 400 °C for 3 hours in a hydrogen-argon atmosphere (H2:Ar = 5:5), and then gradually cooled to room temperature. Metal nickel-filled carbon nanotubes Ni@SWCNT were obtained. As Figure 2 shown in the NiCl2@SWCNT thermogravimetric curve (the residual mass of pure single-walled carbon tubes is 1.6%, and the residual mass of nickel chloride-embedded carbon tubes is 25.7%. The remaining substance after the TG test of nickel chloride-embedded carbon tubes is nickel oxide. Excluding the residual mass of carbon tubes, the mass of nickel oxide is 24.1%. After conversion, the mass of nickel chloride is 41.81%).

[0051] (2) At room temperature, 5 mg of the Ni@SWCNT prepared in step (1) was placed in 20 mL of a 0.05 M chloroplatinic acid solution, and stirred at a speed of 200 rpm at room temperature for 3 h on a magnetic stirrer. After removing the magnetic stir bar, the mixture was poured into a centrifuge tube, and the mixture was centrifuged at a speed of 8000 rpm for 30 min using a high-speed centrifuge, and the supernatant was poured off. 10 mL of deionized water was added to mix evenly with the lower black precipitate. After adding the magnetic stir bar, it was stirred at a speed of 200 rpm for 1 min, and then the magnetic stir bar was taken out and centrifuged at a speed of 8000 rpm for 10 min to wash the chloroplatinic acid on the outer wall of the carbon tube. The washing was repeated until the filtrate was colorless. Finally, the precipitate was placed in a vacuum oven at 60 °C and dried overnight. The dried black powder sample was annealed at a temperature of 400 °C for 3 hours in a hydrogen-argon mixed atmosphere of 2:8, and the obtained black product was single-atom platinum-nickel alloy-embedded carbon nanotubes PtNi@SWCNT. The XPS characterization of the obtained product is as Figure 7 shown in and Table 1 below.

[0052] Table 1: XPS data of PtNi@SWCNT samples

[0053]

[0054] Comparative Example 1

[0055] This comparative example provides a method for preparing platinum-embedded carbon nanotubes, which is as follows:

[0056] After mixing 10 - 30 mg of pretreated carbon nanotubes with 80 - 200 mg of platinum acetylacetonate, at 10 -3They were sealed together in a quartz tube under a vacuum of Pa and then heated in a tube furnace at a temperature of 150 - 180 °C for 3 days. After annealing, the black powder was taken out and further washed with deionized water, ultrasonically cleaned and centrifuged to collect it in order to remove the residual precursors outside the CNTs. Then, the obtained black precipitate was placed in a blast drying oven at 60 °C for 10 h. Finally, the black powder was annealed at a temperature of 500 °C in a hydrogen - argon atmosphere for 1 hour and then gradually cooled to room temperature. Platinum - metal - filled carbon nanotubes Pt@SWCNT were obtained.

[0057] Comparative Example 2

[0058] At room temperature, 5 mg of pre - treated carbon nanotubes were placed in 20 mL of 0.05 M chloroplatinic acid solution and stirred at 200 rpm at room temperature for 3 h on a magnetic stirrer. After removing the magnetic stir bar, the mixture was poured into a centrifuge tube and centrifuged at 8000 rpm for 30 min using a high - speed centrifuge, and the supernatant was poured off. 10 mL of deionized water was added to mix evenly with the black precipitate in the lower layer. After adding the magnetic stir bar, it was stirred at 200 rpm for 1 min, then the magnetic stir bar was taken out and centrifuged at 8000 rpm for 10 min to wash away the chloroplatinic acid on the outer wall of the carbon nanotubes. The washing was repeated until the filtrate was colorless. Finally, the precipitate was placed in a vacuum oven at 60 °C for overnight drying. The black powder sample obtained after drying was annealed at a temperature of 400 °C in a hydrogen - argon mixed atmosphere of 2:8 for 3 hours, and the obtained black product was single - atom platinum - embedded carbon nanotubes Pt@SWCNT.

[0059] Test Example 1

[0060] The preparation process of the platinum - nickel single - atom alloy - embedded carbon nanotubes prepared in Test Example 1 is shown in Figure 1 The TEM image results of the platinum - nickel single - atom alloy - embedded carbon nanotubes prepared in Test Example 1 are shown in Figure 3 .

[0061] It can be seen from Figure 3 that in the platinum - nickel single - atom alloy - embedded carbon nanotubes, platinum is uniformly embedded in the nickel substrate in the form of single atoms and is uniformly distributed along the carbon nanotubes, and the dispersion of platinum is significantly improved.

[0062] Test Example 2

[0063] Test the oxygen reduction performance of the platinum-nickel single-atom alloy embedded carbon nanotube catalyst prepared in Test Example 1. Test method: PtNi@SWCNT is used as the working electrode, a mercury / mercuric oxide electrode (Hg / HgO) is used as the reference electrode, and a graphite rod is used as the counter electrode. Before the test, the glassy carbon electrode (GC) is polished smoothly with aqueous alumina solutions of 1.0 μm, 0.3 μm, and 0.05 μm on a polishing cloth, and then the electrode is rinsed with deionized water and dried. The SWCNT, Pt@SWCNT, and PtNi@SWCNT materials are ultrasonicated in an aqueous solution containing 0.5% wt Nafion film-forming agent for 120 minutes to obtain a uniformly dispersed suspension. After sonication, 8 μl of the suspension is deposited on the glassy carbon working electrode and allowed to air-dry naturally to complete the preparation of the working electrode.

[0064] Use linear sweep voltammetry to test the oxygen reduction performance of the platinum-nickel single-atom alloy embedded carbon nanotube prepared in Example 1. A typical three-electrode system is adopted. In a 0.1 M KOH solution saturated with O2, a mercury / mercuric oxide electrode is used as the reference electrode, a graphite rod is used as the counter electrode, and the platinum-nickel single-atom alloy embedded carbon nanotube is used as the working electrode. The test is carried out under the conditions of a voltage range from 0.2 V to -0.9 V and a scan rate of 5 mV / s. The test results are as Figure 4 shown.

[0065] It can be seen from the figure that the platinum single-atom alloy embedded carbon nanotube prepared in this example has more excellent stability, cycling performance, and reaction kinetics compared with the existing noble metal catalysts and the catalyst of Comparative Example 2.

[0066] Test Example 3

[0067] Use chronoamperometry to test the stability of the platinum-nickel single-atom alloy embedded carbon nanotube prepared in Example 1. A typical three-electrode system is adopted. In a 0.1 M KOH solution saturated with O2, a mercury / mercuric oxide electrode is used as the reference electrode, a graphite rod is used as the counter electrode, and a copper electrode coated with the platinum-nickel single-atom alloy embedded carbon nanotube is used as the working electrode. The current corresponding to the half-wave potential (0.85 V) is selected as the test current, and the test duration is 24 h. The test results are as Figure 5 shown.

[0068] It can be seen that the platinum single-atom alloy embedded carbon nanotube catalyst prepared in this example has better stability and higher activity than the existing commercial platinum carbon.

[0069] Example 2

[0070] This example provides a preparation method of a single-atom platinum-nickel alloy embedded carbon nanotube, which includes the following steps:

[0071] (1) Filling of nickel in carbon nanotubes: At room temperature, 100 mg of anhydrous nickel chloride (NiCl2) and 20 mg of pretreated single-walled carbon nanotubes were sealed together in a quartz tube under a vacuum of 5×10 -4 Pa, and then heated in a tube furnace at a temperature of 1050 °C for 3 days. After annealing, the black powder was taken out and further washed with deionized water, and ultrasonic cleaning and centrifugation were used to remove the residual precursors outside the CNTs. Finally, the black powder was annealed at a temperature of 300 °C for 2 hours in a hydrogen-argon atmosphere (H2:Ar = 2:8), and then gradually cooled to room temperature. Metal nickel-filled carbon nanotubes Ni@SWCNT were obtained.

[0072] (2) At room temperature, 10 - 30 mg of Ni@SWCNT prepared in step (1) was placed in a 0.001 M chloroplatinic acid solution and stirred at room temperature for 1 h at a speed of 500 rpm on a magnetic stirrer. After removing the magnetic stir bar, the mixture was poured into a centrifuge tube, and the mixture was centrifuged at a speed of 8000 rpm for 30 min using a high-speed centrifuge, and the supernatant was poured off. 50 mL of deionized water was added to mix evenly with the lower black precipitate, a magnetic stir bar was added and stirred at a speed of 500 rpm for 5 min, then the magnetic stir bar was taken out, and centrifuged at a speed of 9000 rpm for 20 min to wash away the chloroplatinic acid on the outer wall of the carbon tube, and the washing was repeated until the filtrate was colorless. Finally, the precipitate was placed in a vacuum oven at 80 °C and dried overnight. The dried black powder sample was annealed at a temperature of 300 °C for 2 hours in a hydrogen-argon mixed atmosphere of 3:7, and the obtained black product was single-atom platinum-nickel alloy-embedded carbon nanotubes PtNi@SWCNT.

[0073] The ORR performance of the sample in this example was detected: the half-wave potential was 0.855 V, and the limiting current density was 5.5 mA / cm 2 After 24 h of stability testing, the half-wave potential dropped to 0.846 V, and the limiting current density was 5.2 mA / cm 2 . It can be found by TEM detection that in the platinum-nickel single-atom alloy-embedded carbon nanotubes, platinum is uniformly embedded in the nickel substrate in the form of single atoms and is uniformly distributed along the carbon nanotubes, and the dispersion of platinum has been significantly improved. And it also has more excellent stability, cycling performance, reaction kinetics and activity compared with the existing noble metal catalysts and the catalyst in Comparative Example 2.

[0074] Example 3

[0075] This example provides a preparation method of single-atom platinum-nickel alloy-embedded carbon nanotubes, including the following steps:

[0076] (1) Filling of nickel in carbon nanotubes: At room temperature, 100 mg of anhydrous nickel chloride (NiCl2) and 40 mg of pretreated single-walled carbon nanotubes were in 10-4 They were sealed together in a quartz tube under a vacuum of Pa, and then heated in a tube furnace at a temperature of 1100 °C for 4 days. After annealing, the black powder was taken out and further washed with deionized water, and ultrasonic cleaning and centrifugation were used to remove the residual precursors outside the CNTs. Finally, the black powder was annealed at a temperature of 500 °C for 4 hours in a hydrogen-argon atmosphere (H2:Ar = 5:5), and then gradually cooled to room temperature. Metal nickel-filled carbon nanotubes Ni@SWCNT were obtained.

[0077] (2) At room temperature, 30 mg of the Ni@SWCNT prepared in step (1) was placed in a 0.5 M chloroplatinic acid solution and stirred at room temperature at a speed of 1000 rpm on a magnetic stirrer for 12 h. After removing the magnetic stir bar, the mixture was poured into a centrifuge tube, and the mixture was centrifuged at a speed of 8000 rpm for 30 min using a high-speed centrifuge, and the supernatant was poured off. 100 mL of deionized water was added to mix evenly with the lower black precipitate, a magnetic stir bar was added and stirred at a speed of 1000 rpm for 10 min, then the magnetic stir bar was taken out, and centrifuged at a speed of 10000 rpm for 30 min to wash the chloroplatinic acid on the outer wall of the carbon tube. The washing was repeated until the filtrate was colorless. Finally, the precipitate was placed in a vacuum oven at 120 °C and dried overnight. The black powder sample obtained after drying was annealed at a temperature of 600 °C for 4 hours in a 5:5 hydrogen-argon mixed atmosphere, and the obtained black product was single-atom platinum-nickel alloy-embedded carbon nanotubes PtNi@SWCNT.

[0078] The ORR performance of the sample in this example was detected: the half-wave potential was 0.862 V, and the limiting current density was 4.7 mA / cm 2 After 24 h of stability testing, the half-wave potential dropped to 0.832 V, and the limiting current density was 4.5 mA / cm 2 . It was found by TEM detection that in the platinum-nickel single-atom alloy-embedded carbon nanotubes, platinum was uniformly embedded in the nickel substrate in the form of single atoms and was uniformly distributed along the carbon nanotubes, and the dispersion of platinum was significantly improved. And it also has more excellent stability, cycling performance, reaction kinetics and activity compared with the existing noble metal catalysts and the catalyst in Comparative Example 2.

[0079] Example 4

[0080] The difference between this example and Example 1 is only that: the transition metal is replaced by cobalt.

[0081] The ORR performance of the sample in this example was detected: the half-wave potential was 0.846 V, and the limiting current density was 5.6 mA / cm 2 After 24 h of stability testing, the half-wave potential dropped to 0.845 V, and the limiting current density was 5.5 mA / cm 2It can be found by TEM detection that in the carbon nanotubes embedded with platinum-cobalt single-atom alloy, cobalt is uniformly embedded in the nickel substrate in the form of single atoms and is uniformly distributed along the carbon nanotubes, and the dispersion of cobalt is significantly improved. Moreover, compared with the existing noble metal catalysts and the catalyst of Comparative Example 2, it also has more excellent stability, cycling performance, reaction kinetics and activity.

[0082] Example 5

[0083] The difference between this example and Example 1 is only that: the transition metal is replaced by copper.

[0084] After testing, the ORR performance of the sample in this example: the half-wave potential is 0.835V, and the limiting current density is 4.3mA / cm 2 After 24h of stability test, the half-wave potential drops to 0.828V, and the limiting current density is 4.4mA / cm 2 It can be found by TEM detection that in the carbon nanotubes embedded with platinum-copper single-atom alloy, platinum is uniformly embedded in the copper substrate in the form of single atoms and is uniformly distributed along the carbon nanotubes, and the dispersion of platinum is significantly improved. Moreover, compared with the existing noble metal catalysts and the catalyst of Comparative Example 2, it also has more excellent stability, cycling performance, reaction kinetics and activity.

[0085] Example 6

[0086] The difference between this example and Example 1 is only that: anhydrous nickel chloride is replaced by anhydrous nickel carbonate.

[0087] After testing, the ORR performance of the sample in this example: the half-wave potential is 0.850V, and the limiting current density is 5.1mA / cm 2 After 24h of stability test, the half-wave potential drops to 0.847V, and the limiting current density is 5.0mA / cm 2 It can be found by TEM detection that in the carbon nanotubes embedded with platinum-nickel single-atom alloy, platinum is uniformly embedded in the nickel substrate in the form of single atoms and is uniformly distributed along the carbon nanotubes, and the dispersion of platinum is significantly improved. Moreover, compared with the existing noble metal catalysts and the catalyst of Comparative Example 2, it also has more excellent stability, cycling performance, reaction kinetics and activity.

[0088] Example 7

[0089] The difference between this example and Example 1 is only that: anhydrous nickel chloride is replaced by anhydrous molybdenum carbonate.

[0090] After testing, the ORR performance of the sample in this example: the half-wave potential is 0.851V, and the limiting current density is 5.3mA / cm 2 After 24h of stability test, the half-wave potential drops to 0.845V, and the limiting current density is 5.3mA / cm2 It can be found by TEM detection that in the carbon nanotubes embedded with platinum-molybdenum single-atom alloy, platinum is uniformly embedded in the molybdenum substrate in the form of single atoms and is uniformly distributed along the carbon nanotubes, and the dispersion of platinum has been significantly improved. Moreover, compared with the existing noble metal catalysts and the catalyst of Comparative Example 2, it also has more excellent stability, cycle performance, reaction kinetics and activity.

[0091] Example 8

[0092] The difference between this example and Example 1 is only that anhydrous nickel chloride is replaced by anhydrous copper carbonate.

[0093] After testing, the ORR performance of the sample in this example: the half-wave potential is 0.836V, and the limiting current density is 4.6mA / cm 2 After 24h of stability test, the half-wave potential drops to 0.832V, and the limiting current density is 4.7mA / cm 2 It can be found by TEM detection that in the carbon nanotubes embedded with platinum-copper single-atom alloy, platinum is uniformly embedded in the copper substrate in the form of single atoms and is uniformly distributed along the carbon nanotubes, and the dispersion of platinum has been significantly improved. Moreover, compared with the existing noble metal catalysts and the catalyst of Comparative Example 2, it also has more excellent stability, cycle performance, reaction kinetics and activity.

[0094] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

[0095] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A platinum single-atom transition metal alloy encapsulated carbon nanotube, comprising a carbon nanotube having an open defect feature; a transition metal M filled in the inner cavity of the carbon nanotube, and platinum atoms dispersed in the inner cavity of the carbon nanotube in a single-atom form.

2. The platinum single-atom transition metal alloy-embedded carbon nanotube according to claim 1, wherein The filling mass ratio of the transition metal M in the carbon nanotube is 10%-50%.

3. The platinum single-atom transition metal alloy-embedded carbon nanotube according to claim 1, wherein The filling amount of the transition metal in the carbon nanotube is, atomic ratio: C:M = 95:1 - 95:

4.

4. The platinum single-atom transition metal alloy-embedded carbon nanotube according to claim 1, characterized in that, The filling amount of the platinum atoms in the carbon nanotube is, atomic ratio: C:Pt = 95:4 - 95:

1.

5. The platinum single-atom transition metal alloy embedded carbon nanotube according to claim 1, characterized in that, The carbon nanotube is selected from: single-walled carbon nanotubes, multi-walled carbon nanotubes.

6. The platinum single-atom transition metal alloy-embedded carbon nanotube according to claim 1, characterized in that, The transition metal M is selected from cobalt, nickel, copper, molybdenum.

7. The preparation method of the platinum single-atom transition metal alloy encapsulated carbon nanotube according to any one of claims 1-6, comprising: preparing a carbon nanotube having an open defect feature; filling a transition metal in the carbon nanotube: after the transition metal source and the nanotube are mixed, high-temperature filling is carried out under vacuum conditions, and after the first purification and the first annealing, the first carbon nanotube filled with the transition metal is obtained; incorporating platinum single atoms into the first carbon nanotube: the first carbon atoms are fully mixed and filled in a solution dispersed with chloroplatinic acid, and after the second purification and the second annealing, the target product is obtained.

8. The preparation method of the platinum single-atom transition metal alloy embedded carbon nanotube according to claim 7, wherein The transition metal source is selected from: chlorides, carbonates of transition metals.

9. The preparation method of the platinum single-atom transition metal alloy embedded carbon nanotube according to claim 7, characterized in that The mixing and filling is carried out under stirring.

10. The application of the platinum single-atom transition metal alloy encapsulated carbon nanotube according to any one of claims 1-6 in redox catalytic reactions.

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