A method for preparing a supported noble metal nanomaterial by introducing a closed borane cluster in an MXene matrix

Abstract

The application provides a method for preparing a supported nanometer noble metal by introducing a closed borane cluster into an MXene matrix, and belongs to the technical field of nanometer noble metal materials. The supported nanometer noble metal is prepared by introducing a closed borane cluster into an MXene matrix. A weak reducing agent, i.e. the closed borane cluster with weak reducing capacity, is first prepositioned on the surface of the MXene through a solvent removal in-situ nucleation growth method, then a noble metal salt is introduced, so that the noble metal salt is in-situ reduced on the surface of the MXene and attached to the surface of the MXene, the controllable reduction of noble metal ions is realized, and then a high-temperature annealing treatment is performed to stabilize the structure of the material, so that a supported nanometer noble metal material with small size and high dispersity is obtained.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, and more particularly to a method for preparing supported nanomaterials by introducing closed borane clusters into an MXene matrix. Background Technology

[0002] Precious metals have wide applications in fields including petrochemicals, biomedicine, energy production / storage / conversion, and environmental pollution treatment. However, the scarcity of precious metals and the resulting cost issues hinder their large-scale utilization. In most cases, precious metals are used as catalysts, a process that occurs on the surface of the precious metal, involving only a few atomic layers, with most of the precious metal atoms in the bulk phase failing to participate in the reaction. Nanostructuring precious metal materials has become an effective method to improve the atomic utilization rate and activity per unit mass of precious metals, promoting green production.

[0003] At present, the development of reliable precious metal nanotechnology, especially the preparation of supported precious metals, has become the focus of attention of both academia and industry. Traditionally, the methods for introducing nano-precious metals onto specific carriers are usually as follows: (1) Mixing the carrier, sodium borohydride, and precious metal salt together, and using the reducing properties of sodium borohydride to convert the precious metal salt into a zero-valent form and attach it to the carrier. This method is simple, but the strong reducing properties of sodium borohydride can easily cause the precious metal atoms to aggregate, forming larger nano-precious metal particles; (2) Mixing the carrier, precious metal salt, and some reducing molecules (such as ascorbic acid) together, and then reducing the precious metal onto the carrier by a high-temperature hydrothermal method. This method can obtain uniformly dispersed precious metal nanoparticles, but it has problems such as high energy consumption and difficulty in large-scale production; (3) Introducing the precious metal salt into the carrier by impregnation or co-precipitation, and then using hydrogen as a reducing agent at high temperature to convert the precious metal salt attached to the carrier into a zero-valent form. This method is cumbersome to operate, has high energy consumption, and has safety risks. Against this backdrop, developing supported nanomaterials for noble metals that are simple to operate, low in cost, have good dispersion and small scale, and are easy to scale up for mass production has become an important research direction. MXene is a material with rich electrical properties and a layered structure, which is conducive to exposing more metal sites. This material has wide applications in chemical catalysis, new energy catalysis, and environmental catalysis. Therefore, developing new technologies for the controllable construction of supported nanomaterials on MXene is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing supported nano-noble metals by introducing closed borane clusters into an MXene matrix. The prepared nano-noble metals have good dispersion and small size, and are easy to prepare in batches.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing supported nano-noble metals by introducing closed borane clusters into an MXene matrix, comprising the following steps:

[0007] MXene and closed borane clusters were mixed in an organic solvent, the organic solvent was removed, and the borane clusters were loaded to obtain borane cluster-MXene;

[0008] The borane cluster-MXene was mixed with a noble metal salt solution and subjected to a reduction reaction to obtain a complex;

[0009] The composite was annealed to obtain a supported nanomaterial of noble metal based on MXene.

[0010] Preferably, the anions of the closed borane clusters include dodecahydrododecorane cluster anions, decahydrodecaborane cluster anions, hexahydrohexaborane cluster anions, or heptahydrohexaborane cluster anions; the cations of the closed borane clusters include organic ammonium cations.

[0011] Preferably, the organic ammonium cation includes tetrabutylammonium cation or tetraethylammonium cation.

[0012] Preferably, the mass ratio of MXene to closed borane cluster is 1:0.5 to 1:5.

[0013] Preferably, the loading temperature of the borane cluster is room temperature, the loading time is 0.5~4h, and the stirring speed is 500~2000r / min.

[0014] Preferably, the noble metal salt in the noble metal salt solution includes one or more of the following: chloroauric acid, chloroplatinic acid, sodium chloropalladium, sodium chloroaurate, potassium chloroaurate, potassium chloroplatinic acid, silver nitrate, silver ammonia, ruthenium trichloride, ammonium hexachlororuthenate, iridium trichloride, hexairinic acid, and rhodium trichloride.

[0015] Preferably, the concentration of the noble metal salt solution is 1~100 mmol / L; the molar ratio of the borane cluster to the noble metal salt in the borane cluster-MXene is 1:1~10:1.

[0016] Preferably, the reduction reaction is carried out at a temperature of 60~150℃ for a time of 0.5~4h.

[0017] Preferably, the annealing treatment is performed at a temperature of 400~1200℃ for 1~4 hours.

[0018] This invention provides a method for preparing supported nano-noble metals by introducing closed borane clusters into an MXene matrix. MXene possesses excellent electrical properties and a layered structure that facilitates metal adhesion and exposure, which is beneficial for surface-reaction-based catalytic processes, making it a suitable support for constructing metal-based catalysts in this invention. This invention prepares supported nano-noble metals by introducing closed borane clusters into an MXene matrix. First, closed borane clusters (weak reducing agents) with weak reducing ability are pre-placed on the MXene surface through in-situ nucleation growth via solvent removal. Then, noble metal salts are introduced, enabling in-situ reduction and attachment of the noble metal salts to the MXene surface, achieving controllable reduction of noble metal ions. Finally, high-temperature annealing stabilizes the material structure, resulting in supported nano-noble metal materials with small size and high dispersion.

[0019] In this invention, the borane clusters have a weak reducing ability, and the mild reducing performance avoids the uncontrollable aggregation of metal particles caused by violent reduction. At the same time, the borane clusters are introduced into the MXene surface with a layered structure. After the noble metal ions are reduced in situ on the MXene surface, the layered two-dimensional surface of MXene can play a confinement role for the nano-metal, thereby ensuring that the supported nano-metal exhibits a highly dispersed and small-sized effect.

[0020] The method of this invention can be extended to the controllable preparation of supported noble metals such as supported nano-platinum, supported nano-palladium, and supported nano-gold. The method has good reliability, repeatability, and scalability, which is beneficial for the mass production of supported nano-noble metals. Attached Figure Description

[0021] Figure 1 A scanning electron microscope image of MXene prepared in Example 1;

[0022] Figure 2 A scanning electron microscope image of Pt / MXene prepared in Example 1;

[0023] Figure 3 The images are transmission electron microscope images of Pt / Mxene prepared in Example 1; where (i) is a transmission electron microscope image with a scale bar of 500 nm, (ii) is a magnified view of a local area in (i), (iii) is a magnified view of another local area in (i), and (iv) is a high-resolution transmission electron microscope image of the high-brightness nanoparticles shown in (i).

[0024] Figure 4 Elemental distribution imaging of Pt / MXene prepared in Example 1;

[0025] Figure 5 X-ray powder diffraction signals of MXene and Pt / MXene prepared in Example 1;

[0026] Figure 6 The X-ray powder diffraction signals of Pd / MXene prepared in Example 2 and MXene in Example 1 are shown.

[0027] Figure 7 The X-ray powder diffraction signals of Au / MXene prepared in Example 3 and MXene in Example 1 are shown. Detailed Implementation

[0028] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.

[0029] This invention provides a method for preparing supported nano-noble metals by introducing closed borane clusters into an MXene matrix, comprising the following steps:

[0030] MXene and closed borane clusters were mixed in an organic solvent, the organic solvent was removed, and the borane clusters were loaded to obtain borane cluster-MXene;

[0031] The borane cluster-MXene was mixed with a noble metal salt solution and subjected to a reduction reaction to obtain a complex;

[0032] The composite was annealed to obtain a supported nanomaterial of noble metal based on MXene.

[0033] The present invention does not have any particular limitation on the MXene, and it can be prepared according to methods well known in the art; in the embodiments of the present invention, specifically 2 g of titanium aluminum carbide (Ti3AlC2) powder is dispersed in 100 mL of HF (40wt%) solution, magnetically stirred for 24 h, ultrasonically treated for 3 h, magnetically stirred for another 24 h, the solution is removed by vacuum filtration, the resulting filter cake is washed with water, and dried in a forced-air drying oven to obtain MXene.

[0034] In this invention, the anion of the closed borane cluster preferably includes the dodecahydrododecorane cluster anion ([B 12 H 12 ] 2- ), decahydroborane cluster anion ([B 10 H 10 ] 2- ), hexahydrohexaborane cluster anion ([B6H6) 2- () or heptahydrohexaborane cluster anion ([B6H7) - ).

[0035] In this invention, the cation of the closed borane cluster preferably includes an organic ammonium cation; the organic ammonium cation preferably includes a tetrabutylammonium cation (TBA). + ) or tetraethylammonium cation (TEA)+ ).

[0036] In embodiments of the present invention, the closed borane cluster is preferably (TBA)2[B 12 H 12 ].

[0037] In this invention, the mass ratio of MXene to closed borane cluster is preferably 1:0.5 to 1:5, more preferably 1:1 to 1:4, and even more preferably 1:2 to 3.138.

[0038] In this invention, the organic solvent is preferably one or more of ethanol, methanol, acetonitrile, ethyl acetate, dichloromethane and chloroform, more preferably ethanol; when the organic solvent is two or more of the above, this invention does not have a special limitation on the ratio of different kinds of organic solvents, and any ratio is acceptable.

[0039] In this invention, MXene and closed borane clusters are preferably dissolved separately in an organic solvent, and the resulting two liquids are mixed under magnetic stirring. The borane clusters are then loaded under continuous magnetic stirring. This invention does not have a specific limitation on the amount of organic solvent used, as long as the materials are uniformly dispersed.

[0040] In this invention, the loading temperature of the borane cluster is preferably room temperature, the loading time is preferably 0.5~4h, more preferably 2~4h, and the stirring speed is preferably 500~2000 r / min, more preferably 1000~1500 r / min.

[0041] After loading the borane clusters, the present invention preferably removes the organic solvent by rotary evaporation under reduced pressure to promote the attachment of the borane clusters to the MXene surface to obtain borane cluster-MXene, and then disperses the borane cluster-MXene in water for subsequent steps.

[0042] In this invention, the precious metal salt in the precious metal salt solution preferably includes one or more of the following: chloroauric acid, chloroplatinic acid, sodium chloropalladium, sodium chloroaurate, potassium chloroaurate, potassium chloroplatinate, silver nitrate, silver ammonia, ruthenium trichloride, ammonium hexachlororuthenate, iridium trichloride, hexairinic acid, and rhodium trichloride. When the precious metal salt is two or more of the above, this invention does not have a special limitation on the proportion of different types of precious metal salts, and any ratio is acceptable.

[0043] In this invention, the concentration of the noble metal salt solution is preferably 1~100 mmol / L, more preferably 8.23~25.39 mmol / L, and even more preferably 13.59~20 mmol / L.

[0044] In this invention, the molar ratio of the borane cluster to the noble metal salt in the borane cluster-MXene is preferably 1:1 to 10:1, more preferably 2 to 8:1, and even more preferably 2.5 to 5:1.

[0045] The present invention preferably involves adding an aqueous solution of a noble metal salt to a borane cluster-MXene in an oil bath under reflux conditions, and continuing the reduction reaction under reflux conditions.

[0046] In this invention, the temperature of the reduction reaction is preferably 60~150℃, more preferably 80~120℃, and the time is preferably 0.5~4h, more preferably 2~3h.

[0047] After the reduction reaction, the present invention preferably cools the obtained suspension and filters it under reduced pressure, washes the obtained filter cake three times with water and ethanol in sequence, dries it in a 60°C forced-air drying oven, and then anneals it in a tube furnace.

[0048] In this invention, the annealing temperature is preferably 400~1200℃, more preferably 600~1000℃, and even more preferably 800~900℃; the annealing time is preferably 1~4h, more preferably 2~3h; and the atmosphere is nitrogen. This invention, through annealing, can transform the unstable amorphous structure in MXene into a stable crystalline structure, while simultaneously removing the water of crystallization from the MXene surface and promoting a more stable bond between the nano-noble metals on the MXene surface and MXene.

[0049] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0050] Unless otherwise specified, the experimental methods described in the various embodiments of this invention are conventional methods; unless otherwise specified, the reagents and raw materials described below are all commercially available.

[0051] Example 1

[0052] 2 g of titanium aluminum carbide (Ti3AlC2) powder was weighed and dispersed in 100 mL of HF (40wt%) solution and magnetically stirred for 24 h. After ultrasonic treatment for 3 h and magnetic stirring for another 24 h, the solution was removed by vacuum filtration. The filter cake was washed with water three times and dried in a forced-air drying oven at 60 °C for 6 h to obtain MXene.

[0053] Take 100 mg MXene and 313.8 mg (0.5 mmol) of closed borane cluster ((TBA)2[B 12 H 12The two liquids were dispersed separately in 50 mL of ethanol. The two liquids were mixed under magnetic stirring at a speed of 1000 r / min and stirred magnetically for 4 h. The ethanol was removed by rotary evaporation under reduced pressure. The remaining solid was redispersed in 200 mL of water and transferred to a round-bottom flask.

[0054] The round-bottom flask was transferred to an oil bath at 120°C, and 24.3 mL of an 8.23 ​​mmol / L K2PtCl6 (0.2 mmol) aqueous solution was added under reflux. The mixture was refluxed for another 2 h. After cooling the resulting suspension, it was filtered under reduced pressure. The resulting filter cake was washed three times with water and ethanol, and dried in a forced-air drying oven at 60°C. The resulting solid was annealed in a tube furnace at 800°C for 2 h under a nitrogen atmosphere to obtain MXene material loaded with nano-platinum, named Pt / MXene.

[0055] Example 2

[0056] MXene 100 mg (prepared in Example 1) and 313.8 mg (0.5 mmol) of closed borane cluster ((TBA)2[B 12 H 12 The two liquids were dispersed in 50 mL of ethanol and mixed under magnetic stirring at 1000 r / min for 4 h. The ethanol was removed by rotary evaporation under reduced pressure. The remaining solid was redispersed in 200 mL of water and transferred to a round-bottom flask.

[0057] The round-bottom flask was transferred to an oil bath at 120°C, and 14.7 mL of a 13.59 mmol / L Na₂PdCl₄ (0.2 mmol) aqueous solution was added under reflux. The mixture was refluxed for another 2 h. After cooling the resulting suspension, it was filtered under reduced pressure. The resulting filter cake was washed three times with water and ethanol, and then dried in a forced-air drying oven at 60°C. The resulting solid was annealed in a tube furnace at 800°C for 2 h under a nitrogen atmosphere to obtain MXene material loaded with palladium nanoparticles, which was named Pd / MXene.

[0058] Example 3

[0059] MXene 100 mg (prepared in Example 1) and 313.8 mg (0.5 mmol) of closed borane cluster ((TBA)2[B 12 H 12 The two liquids were dispersed separately in 50 mL of ethanol. The two liquids were mixed under magnetic stirring at a speed of 1000 r / min and stirred magnetically for 4 h. The ethanol solution was removed by rotary evaporation under reduced pressure. The remaining solid was redispersed in 200 mL of water and transferred to a round-bottom flask.

[0060] Transfer the round-bottom flask to an oil bath at 120°C, and add 7.8 mL of HAuCl4·3H2O at a concentration of 25.39 mmol / L under reflux. (0.2 mmol) aqueous solution was refluxed for 2 h. After cooling the resulting suspension, it was filtered under reduced pressure. The resulting filter cake was washed three times with water and ethanol, and dried in a forced-air drying oven at 60 °C. The resulting solid was annealed in a tube furnace at 800 °C for 2 h under a nitrogen atmosphere to obtain MXene material loaded with gold nanoparticles, named Au / MXene.

[0061] Discussion of characterization results

[0062] Figure 1 The image shows a scanning electron microscope image of MXene prepared in Example 1. MXene exhibits an accordion-shaped two-dimensional thin-layer stacked morphology.

[0063] Figure 2 The scanning electron microscope image of Pt / MXene prepared in Example 1 shows that, in addition to the two-dimensional thin-layer stacked morphology of MXene, a large number of nanoparticles are uniformly loaded on the two-dimensional nanosheets, with particle sizes ranging from 5 to 30 nm.

[0064] Figure 3 The images shown are transmission electron microscope (TEM) images of the Pt / Mxene prepared in Example 1, where (i) is a TEM image with a scale bar of 500 nm, (ii) is a magnified view of a local area in (i), (iii) is a magnified view of another local area in (i), and (iv) is a high-resolution TEM image of the high-brightness nanoparticles shown in (i), exhibiting obvious lattice fringes. In high-angle annular dark-field (HAADF) mode, platinum, with its larger atomic mass, exhibits higher brightness; therefore, small-sized, highly dispersed platinum nanoparticles can be seen uniformly dispersed on the surface of the MXene matrix. Figure 3 (ii) and interior ( Figure 3 (iii) and the lattice fringe spacing is 0.23 nm, indicating that the valence of Pt in Pt / MXene is 0.

[0065] Figure 4 Elemental distribution imaging of the Pt / MXene prepared in Example 1 shows that, in addition to Ti, O, and C in the MXene matrix, platinum is also uniformly dispersed on the surface and inside the two-dimensional stacked structure.

[0066] Figure 5 X-ray powder diffraction signals of MXene and Pt / MXene prepared in Example 1, such as Figure 5As shown, after the formation of Pt / MXene, the main structure of MXene is retained, but a small amount of TiO2 and Pt3Ti are also formed. The X-ray powder diffraction signal of Pt / MXene clearly shows a signal consistent with that of face-centered cubic zero-valent platinum (JCPDS: 04-0802), which is consistent with the results of transmission electron microscopy. These results indicate that by pre-introducing reducing closed-cell borane clusters onto the MXene surface, it is possible to effectively load highly dispersed, small-particle-size zero-valent platinum nanoparticles onto the MXene matrix.

[0067] Figure 6 The X-ray powder diffraction signals of Pd / MXene prepared in Example 2 and MXene in Example 1 are shown below. Figure 6 As shown, after the formation of Pd / MXene, the main structure of MXene is retained, but a very small amount of TiO2 and Pd3Ti are also formed. The X-ray powder diffraction signal of Pd / MXene clearly shows a signal consistent with that of face-centered cubic zero-valent palladium (JCPDS:04-0802), indicating the successful introduction of zero-valent palladium nanoparticles into the MXene matrix. This result demonstrates that by pre-introducing reducible closed-loop borane clusters onto the MXene surface, supported zero-valent palladium nanoparticles can also be constructed on the MXene matrix.

[0068] Figure 7 The X-ray powder diffraction signals of Au / MXene prepared in Example 3 and MXene in Example 1 are compared with those of MXene. Figure 7 As shown, after the formation of Au / MXene, a signal consistent with that of zero-valent gold (JCPDS:04-0784) with a face-centered cubic configuration was clearly observed, indicating the successful introduction of zero-valent gold nanoparticles into the MXene matrix. This result demonstrates that by pre-introducing reducible closed-loop borane clusters onto the MXene surface, it is also possible to construct supported zero-valent gold nanoparticles on the MXene matrix.

[0069] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing supported nano-noble metals by introducing closed borane clusters into an MXene matrix, characterized in that, Includes the following steps: MXene and closed borane clusters were mixed in an organic solvent, the organic solvent was removed, and the borane clusters were loaded to obtain borane cluster-MXene; The borane cluster-MXene was mixed with a noble metal salt solution and subjected to a reduction reaction to obtain a complex; The composite was annealed to obtain a supported nano-noble metal material based on MXene; The anions of the closed borane clusters include dodecahydrododecorane cluster anions, decahydrodecaborane cluster anions, hexahydrohexaborane cluster anions, or heptahydrohexaborane cluster anions. The cations of the closed borane clusters include organic ammonium ions; the organic ammonium ions include tetrabutylammonium ions or tetraethylammonium ions; The borane clusters were loaded at room temperature for 0.5 to 4 hours. The reduction reaction is carried out at a temperature of 60~150℃ for a time of 0.5~4h. The annealing process is carried out at a temperature of 400~1200℃ for 1~4 hours.

2. The method according to claim 1, characterized in that, The mass ratio of MXene to closed borane clusters is 1:0.5 to 1:

5.

3. The method according to claim 2, characterized in that, The stirring speed for loading the borane cluster is 500~2000 r / min.

4. The method according to claim 1, characterized in that, The noble metal salt in the noble metal salt solution includes one or more of the following: chloroauric acid, chloroplatinic acid, sodium chloropalladium, sodium chloroaurate, potassium chloroaurate, potassium chloroplatinic acid, silver nitrate, silver ammonia, ruthenium trichloride, ammonium hexachlororuthenate, iridium trichloride, hexairinic acid, and rhodium trichloride.

5. The method according to claim 4, characterized in that, The concentration of the noble metal salt solution is 1~100 mmol / L; the molar ratio of the borane cluster to the noble metal salt in the borane cluster-MXene is 1:1~10:1.

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