Preparation method of bamboo-like nitrogen-doped carbon nanotube loaded with metal monoatomic atoms and nanoparticles
阅读说明：本技术 一种负载金属单原子和纳米颗粒竹节状氮掺杂碳纳米管的制备方法 (Preparation method of bamboo-like nitrogen-doped carbon nanotube loaded with metal monoatomic atoms and nanoparticles ) 是由 张旭 郭迎春 王小梅 于 2021-10-15 设计创作，主要内容包括：本发明为一种负载金属单原子和纳米颗粒竹节状氮掺杂碳纳米管的制备方法。该方法包括以下步骤：在球磨罐中加入2-甲基咪唑、金属盐、含锌化合物和研磨球,球磨2-8h,得到含有ZIFs单晶的混合物；然后将含有ZIFs单晶的混合物置于石英舟中,在管式炉中以2～5℃min～(-1)从室温升至800～1100℃保持1～3h,自然冷却至室温,最后得到负载金属单原子和纳米颗粒竹节状氮掺杂碳纳米管。本发明无需洗涤、分离等步骤,在光热催化和协同催化等领域有着巨大的潜在应用价值,扩宽了其在催化领域中的应用。(The invention relates to a preparation method of bamboo-like nitrogen-doped carbon nano tubes loaded with metal monoatomic atoms and nano particles. The method comprises the following steps: adding 2-methylimidazole, metal salt, a zinc-containing compound and grinding balls into a ball milling tank, and carrying out ball milling for 2-8h to obtain a mixture containing ZIFs single crystals; then placing the mixture containing ZIFs single crystals in a quartz boat, and placing the quartz boat in a tube furnace at the temperature of 2-5 ℃ for min ‑1 And raising the temperature from the room temperature to 800-1100 ℃, keeping the temperature for 1-3 h, and naturally cooling to the room temperature to obtain the bamboo-shaped nitrogen-doped carbon nano tube loaded with metal monoatomic atoms and nano particles. The method does not need steps such as washing, separation and the like, and has great potential in the fields of photo-thermal catalysis, cooperative catalysis and the likeThe application value of the catalyst widens the application of the catalyst in the field of catalysis.)
1. A preparation method of a bamboo-shaped nitrogen-doped carbon nanotube loaded with metal monoatomic atoms and nano particles is characterized by comprising the following steps:
1) preparation of mixture containing ZIFs single crystal by ball milling method
Adding 2-methylimidazole, metal salt, a zinc-containing compound and grinding balls into a ball milling tank, and carrying out ball milling for 2-8h to obtain a mixture containing ZIFs single crystals;
wherein the total molar amount of the metal salt and the zinc-containing compound corresponding to 1mol of 2-methylimidazole is 0.05-1 mol, and the molar ratio is as follows: zinc-containing compound 1: 1-20;
2) preparation of bamboo-like nitrogen-doped carbon nano-tube loaded with metal monoatomic and nano-particles
Placing the mixture containing the ZIFs single crystals obtained in the last step into a quartz boat, and placing the quartz boat in a tube furnace at the temperature of 2-5 ℃ for min-1And raising the temperature from the room temperature to 800-1100 ℃, keeping the temperature for 1-3 h, and naturally cooling to the room temperature to obtain the bamboo-shaped nitrogen-doped carbon nano tube loaded with metal monoatomic atoms and nano particles.
2. The method for preparing the metal monoatomic and nanoparticle-supported bamboo-like nitrogen-doped carbon nanotube as claimed in claim 1, wherein the diameter of the grinding balls is 0.4cm to 1.0cm, and the number of the grinding balls per 1g of the reactant (i.e., 2-methylimidazole, zinc-containing compound and metal salt) is 2 to 10; the rotating speed of the ball milling tank is 500-.
3. The method for preparing metal-loaded monatomic and nanoparticle bamboo-like nitrogen-doped carbon nanotubes of claim 1, wherein said metal salt is Ni (NO)3)2·6H2O、Ni(NO3)2、NiSO4、NiCl2·6H2O、NiCl2Nickel acetate tetrahydrate (C)4H14NiO8)、Ni(CH3COO)2、Co(NO3)2·6H2O、Co(NO3)2、CoSO4、CoCl2·6H2O、CoCl2Cobalt acetate tetrahydrate (C)4H14CoO8)、Co(CH3COO)2、Fe(NO3)3·9H2O、Fe(NO3)3、Fe2(SO4)3、FeCl3·6H2O、FeCl3Iron acetate tetrahydrate (C)6H17FeO10) And ferrous acetate (C)4H6FeO4) One or more of (a).
4. The method for preparing metal-loaded monatomic and nanoparticle bamboo-like nitrogen-doped carbon nanotubes of claim 1, wherein said zinc-containing compound is one or more of zinc hydroxide, zinc oxide, zinc nitrate, and zinc nitrate hexahydrate.
Technical Field
The invention relates to the technical field of preparation of carbon nanotube one-dimensional composite materials, in particular to a preparation method of bamboo-like nitrogen-doped carbon nanotubes loaded with metal monoatomic atoms and nanoparticles.
Background
Carbon nanotubes are widely used in Energy Storage and conversion, catalytic conversion, lithium ion batteries, sensors, etc. due to their excellent mechanical, electrical and chemical properties (Energy Storage Materials 2021,43, 365-. However, the pure carbon nanotubes have fewer active sites, which limits the application of carbon nanotubes in the field of catalysis. In order to improve the surface chemical property and catalytic performance of the carbon nano tube, nitrogen doping or loading of metal nano particles and single atoms is an effective and feasible method. Nitrogen-doped carbon nanotubes containing metal monoatomic atoms attract people's attention in the field of catalysis due to higher atom utilization rate, excellent selectivity and catalytic activity (adv. mater.2018,30,1706287). In addition, CO is converted using a monatomic catalyst2The photocatalytic transformation into value-added chemicals and fuels has shown great application potential in solving the energy crisis and alleviating the greenhouse effect and is of great interest (nat. energy 2021,6, 807-.
Zeolite Imidazolate Frameworks (ZIFs) are subclasses of MOFs, and due to high nitrogen content, ordered pore structures and flexible and variable metal sites, they are ideal precursors for the preparation of monatomic catalysts (Nano Energy 2020,71, 104547). Various metal monatomic catalysts (Ni, Fe, Co, Zn, etc.) can be prepared by the strategy of pyrolysis of ZIF (adv. Energy mater.2020,10(38), 2001561). However, most of the structures of the currently reported ZIF-derived monatomic catalysts are micron-sized rhombic dodecahedrons, and the structures are mainly microporous (<2nm) structures, so that the catalysts can only be used for surface monatomic sites when participating in catalysis, and active sites embedded inside cannot be effectively utilized, thereby reducing the atom utilization rate (Chem 2020, 6(1), 19-40). The construction of ZIF-derived monatomic catalysts into nanoscale monodisperse nanotubular structures is considered an effective approach to increasing atom utilization (adv. funct. mater.2021,31,2010472). The nano-tubular structure not only can expose internal active sites and improve mass transfer efficiency, but also is an important way for expanding the catalytic application of the material in relation to large-size compounds (adv.mater.2019,31(49), 1906051).
Although few ZIF-derived bamboo-like nanotubes have been reported, they have been preparedThe process is complicated, a large amount of organic solvent is needed in the preparation process, dicyandiamide, melamine and the like are needed in the pyrolysis process, and the reagents are easy to form high-toxicity cyanide during high-temperature pyrolysis (Small 2020,16(41), 2002124). Therefore, a convenient and more environment-friendly novel method for preparing ZIF-derived bamboo-like nanotubes for catalytic conversion of CO is developed2Has excellent development prospect for value-added products.
Disclosure of Invention
The invention aims to provide a preparation method of bamboo-shaped nitrogen-doped carbon nano-tubes loaded with metal single atoms and nano-particles aiming at the defects in the prior art. The method comprises the steps of preparing a mixture containing ZIFs single crystals by a mechanochemical method (ball milling), and then, derivatizing the mixture containing the ZIFs single crystals by a high-temperature pyrolysis method to generate the bamboo-shaped nitrogen-doped carbon nano-tubes loaded with metal single atoms and nano-particles. The method does not need steps such as washing, separation and the like, has great potential application value in the fields of photo-thermal catalysis, cooperative catalysis and the like, and widens the application of the method in the catalysis field.
The technical scheme of the invention is as follows:
a preparation method of a bamboo-shaped nitrogen-doped carbon nanotube loaded with metal monoatomic atoms and nano particles comprises the following steps:
1) preparation of mixture containing ZIFs single crystal by ball milling method
Adding 2-methylimidazole, metal salt, a zinc-containing compound and grinding balls into a ball milling tank, and carrying out ball milling for 2-8h to obtain a mixture containing ZIFs single crystals;
wherein the total molar amount of the metal salt and the zinc-containing compound corresponding to 1mol of 2-methylimidazole is 0.05-1 mol, and the molar ratio is as follows: zinc-containing compound 1: 1-20;
the diameter of the grinding ball is 0.4cm-1.0cm, and the quantity of the grinding balls corresponding to each 1g of reactant (namely 2-methylimidazole, zinc-containing compound and metal salt) is 2-10; the rotation speed of the ball mill is 500-;
the metal salt is Ni (NO)3)2·6H2O、Ni(NO3)2、NiSO4、NiCl2·6H2O、NiCl2Nickel acetate tetrahydrate (C)4H14NiO8)、Ni(CH3COO)2、Co(NO3)2·6H2O、Co(NO3)2、CoSO4、CoCl2·6H2O、CoCl2Cobalt acetate tetrahydrate (C)4H14CoO8)、Co(CH3COO)2、Fe(NO3)3·9H2O、Fe(NO3)3、Fe2(SO4)3、FeCl3·6H2O、 FeCl3Iron acetate tetrahydrate (C)6H17FeO10) And ferrous acetate (C)4H6FeO4) One or more of;
the zinc-containing compound is one or more of zinc hydroxide, zinc oxide, zinc nitrate and zinc nitrate hexahydrate.
2) Preparation of bamboo-like nitrogen-doped carbon nano-tube loaded with metal monoatomic and nano-particles
Placing the mixture containing the ZIFs single crystals obtained in the last step into a quartz boat, and placing the quartz boat in a tube furnace at the temperature of 2-5 ℃ for min-1Raising the temperature from room temperature to 800-1100 ℃, keeping the temperature for 1-3 h, and naturally cooling to room temperature to obtain the bamboo-like nitrogen-doped carbon nano tube loaded with metal monoatomic atoms and nano particles;
the invention has the substantive characteristics that:
in the prior art, most methods for preparing the metal-loaded monatomic bamboo-shaped nitrogen-doped carbon nanotube are liquid phase synthesis, a large amount of solvents and centrifugal separation steps are required in the preparation process, and the metal monatomic and the nanoparticles are difficult to obtain simultaneously. The invention skillfully combines a ball milling method and a pyrolysis method, prepares the bamboo-like nitrogen-doped carbon nanotube loaded with metal monoatomic atoms and nano particles by utilizing a mechanochemical method (solid phase synthesis) and a high-temperature pyrolysis strategy, has simple preparation process (without the steps of washing, separating, drying and the like), and is easy for large-scale production.
The invention has the beneficial effects that:
(1) the invention provides a method for conveniently preparing bamboo-like nitrogen-doped carbon nano tubes loaded with metal monoatomic atoms and nano particles. As can be seen from the attached figures 2-4, the prepared bamboo-shaped nitrogen-doped carbon nanotube has metal nanoparticles and single atoms at the same time. Compared with the traditional micron-sized rhombic dodecahedron-structured ZIFs-derived monatomic catalyst, the bamboo-shaped nanotube is easy to expose more internal active sites and improve the mass transfer efficiency. The properties, the structure and the preparation idea of the material are not reported in the novel literature.
(2) The invention provides a method for preparing a bamboo-like nitrogen-doped carbon nano tube loaded with metal monoatomic and nano-particles by a ball milling method and a pyrolysis method. Compared with the traditional liquid phase synthesis, the ball milling process is solid phase synthesis, no solvent is needed, and the reaction yield is high. The preparation method is novel, the process is simple and feasible, and the cost is low. FIG. 5 shows the result of the material under a sunlight intensity (0.1W/cm)2) The temperature after 5min of irradiation showed that the material temperature could be raised to 73.9 ℃ showing excellent photo-thermal properties. However, the metal-loaded monatomic bamboo-like nitrogen-doped carbon nanotubes could only be raised to 63.2 ℃ under the same conditions (fig. 6). The material obtained by the invention has excellent photo-thermal performance due to the plasma effect of the metal nanoparticles. It can also be seen from fig. 7 that the metal-loaded monatomic and nanoparticle bamboo-like nitrogen-doped carbon nanotubes exhibit superior light absorption properties compared to metal-loaded monatomic bamboo-like nitrogen-doped carbon nanotubes. Therefore, the prepared bamboo-like nitrogen-doped carbon nano tube loaded with metal monoatomic and nano-particles can be used in the fields of photo-thermal catalysis and the like and used for photo-driven CO2Shows excellent catalytic performance in cycloaddition reaction with epoxy bromopropane, and is illuminated under xenon lamp (0.1W/cm)2) When tetrabutylammonium bromide was used as a co-catalyst, the catalytic yield was 99% as determined by NMR spectroscopy. The catalysts reported in the literature must be heated to achieve the same catalytic yield. The invention is easy to realize large-scale and industrialized production when in use, and has better industrial development prospect.
Drawings
FIG. 1 is an SEM photograph of a mixture containing ZIFs single crystals in example 1;
FIG. 2 is an SEM photograph of the bamboo-like nitrogen-doped carbon nanotube loaded with metal monoatomic particles and nanoparticles of example 1;
FIG. 3 is a STEM photograph of the bamboo-like nitrogen-doped carbon nanotube loaded with metal monoatomic and nano-particles in example 1;
FIG. 4 is a HAADF-STEM photograph of the bamboo-like nitrogen-doped carbon nanotube loaded with metal monoatomic and nano-particles in example 1;
FIG. 5 is an infrared thermal imaging photo of the bamboo-like nitrogen-doped carbon nanotube loaded with metal monoatomic particles and nanoparticles in example 1 under one sunlight intensity;
FIG. 6 is an infrared thermal imaging photograph of the bamboo-like N-doped carbon nanotube loaded with metal monoatomic and nano-particles in example 1 under a solar light intensity after metal nano-particles are etched away;
FIG. 7 is a UV spectrum of the metal monatomic and nanoparticle loaded bamboo-like nitrogen-doped carbon nanotube and the bamboo-like nitrogen-doped carbon nanotube having a metal monatomic in example 1;
FIG. 8 shows that the metal monoatomic and nanoparticle-loaded bamboo-like N-doped carbon nanotubes and the metal monoatomic bamboo-like N-doped carbon nanotubes in example 1 catalyze CO2Compared with the cycloaddition reaction yield of the propylene bromide oxide.
Detailed Description
The preparation process comprises the following steps of (1) preparing a mixture containing ZIFs single crystals by using 2-methylimidazole, metal salt and a zinc-containing compound as precursors through a ball milling method, and (2) obtaining the bamboo-shaped nitrogen-doped carbon nano tube loaded with metal single atoms and nano particles through high-temperature pyrolysis.
The preparation process is simple in flow and easy for large-scale preparation, the obtained product has excellent photo-thermal conversion performance and high-activity multifunctional sites, and the bamboo-like nanotubes are easy to expose more internal active sites and improve the mass transfer efficiency; the metal monoatomic and nano-particles are beneficial to increasing the cooperative catalysis capability, and the characteristics enable the micro-nano reactor, the cooperative catalysis and other fields to have great potential application values.
Wherein the metal salt Ni (NO)3)2·6H2O、Ni(NO3)2、NiSO4、NiCl2·6H2O、NiCl2Nickel acetate tetrahydrate (C)4H14NiO8)、Ni(CH3COO)2、Co(NO3)2·6H2O、Co(NO3)2、CoSO4、CoCl2·6H2O、CoCl2Cobalt acetate tetrahydrate (C)4H14CoO8)、Co(CH3COO)2、Fe(NO3)3·9H2O、Fe(NO3)3、Fe2(SO4)3、FeCl3·6H2O、 FeCl3Iron acetate tetrahydrate (C)6H17FeO10) Ferrous acetate (C)4H6FeO4) (ii) a Zinc hydroxide, zinc oxide, zinc nitrate hexahydrate, which are zinc compounds, are known materials.
Example 1:
(1) 28mmol of 2-methylimidazole and 1mmol of Ni (NO) were added to a ball mill pot3)2·6H2O, 5mmol of zinc oxide (the mass of the reactants is 3.0g in total) and 10 grinding balls (the diameter is 0.5cm), and the mixture containing the ZIFs single crystals is obtained by ball milling for 3 hours under the condition that the rotating speed of a ball milling tank is 1000 r/min.
FIG. 1 is an SEM photograph obtained by scanning a mixture containing ZIFs single crystals by using a FEI Nano SEM 450 scanning electron microscope, and it can be seen from the drawing that the single crystals ZIFs have a rhombic dodecahedron structure and the particle size is 200-1000 nm.
(2) Placing the obtained mixture containing ZIFs single crystal in quartz boat, and placing in tube furnace at 5 deg.C for min-1And raising the temperature from the room temperature to 1000 ℃ for 3h, and naturally cooling to the room temperature to obtain the bamboo-shaped nitrogen-doped carbon nano tube loaded with metal monoatomic and nano-particles.
Fig. 2 and 3 are SEM and STEM photographs obtained by scanning metal-loaded monatomic and nanoparticle bamboo-shaped nitrogen-doped carbon nanotubes with a FEI Nano SEM 450 scanning electron microscope, and it can be seen from the photographs that the material exhibits a bamboo-shaped hollow nanostructure. In addition, the formation of Ni nanoparticles (white particles) can also be seen from the figure.
FIG. 4 is a photograph of a metal-loaded monatin and nano-particle bamboo-shaped nitrogen-doped carbon nanotube by using a Titan Themis cube G260-300 spherical aberration correction transmission electron microscope to represent the spherical aberration correction HAADF-STEM, wherein the Ni atoms exist in a monoatomic dispersion form.
FIG. 5 is a graph showing the measurement of solar light intensity (0.1W/cm) of the metal-loaded monatomic and nanoparticle bamboo-like nitrogen-doped carbon nanotubes by an infrared thermal imager (Smart Sensor, ST9550, China) at room temperature (25 ℃)2) Lower infrared thermography picture, it can be seen that the material temperature rose to 73.9 ℃.
FIG. 6 shows the test of the removal of loaded metal monoatomic and nanoparticulate bamboo-like nitrogen-doped carbon nanotubes (etched with 1mol/L H) by an infrared thermal imager (Smart Sensor, ST9550, China) at room temperature (25 deg.C)2SO4Reaction at 90 ℃ for 24h) after the metal nanoparticles are exposed to a solar light intensity (0.1W/cm)2) Lower infrared thermography picture, it can be seen that the material temperature rose to 63.2 ℃.
Fig. 7 is an ultraviolet spectrum of the metal-loaded monatomic and nanoparticle bamboo-like nitrogen-doped carbon nanotubes and the metal-loaded monatomic bamboo-like nitrogen-doped carbon nanotubes tested using an ultraviolet spectrophotometer (CARY 300).
FIG. 8 shows that the metal-loaded monatomic and nanoparticle bamboo-shaped nitrogen-doped carbon nanotube (1) and the metal-loaded monatomic bamboo-shaped nitrogen-doped carbon nanotube (2) catalyze CO2Compared with the cycloaddition reaction yield of the propylene bromide oxide. The cycloaddition reaction conditions are as follows: catalyst (20mg), tetrabutylammonium bromide (21mg), N, N-dimethylformamide (2mL), propylene bromide oxide (0.67mmol), CO2(1atm), xenon full spectrum irradiation (0.1W/cm)2) The reaction was magnetically stirred in a glass vial for 12 h. As shown in fig. 8, the metal-loaded monatomic and nanoparticle bamboo-like nitrogen-doped carbon nanotubes (1, yield 99%) showed superior yields compared to the metal-loaded monatomic bamboo-like nitrogen-doped carbon nanotubes (2, yield 87%) under the same conditions.
Example 2:
(1) adding 28mmol of 2-methylimidazole in a ball milling tank,1mmol of Ni (NO)3)2·6H2O, 5mmol of zinc hydroxide (the mass of the reaction substances is 3.1g in total) and 10 grinding balls (the diameter is 0.5cm), and the mixture containing the ZIFs single crystals is obtained by ball milling for 3 hours at the rotating speed of 800 r/min.
(2) Placing the obtained mixture containing ZIFs single crystal in quartz boat, and placing in tube furnace at 5 deg.C for min-1And raising the temperature from the room temperature to 1100 ℃ for 2h, and naturally cooling to the room temperature to obtain the bamboo-shaped nitrogen-doped carbon nano tube loaded with metal monoatomic atoms and nano particles.
Example 3:
(1) 28mmol of 2-methylimidazole and 1mmol of Ni (NO) were added to a ball mill pot3)2·6H2O, 5mmol of hexahydrate and zinc nitrate (the total mass of reactants is 4.1g) and 10 grinding balls (the diameter is 0.5cm), and the mixture containing the ZIFs single crystals is obtained by ball milling for 3 hours under the condition that the rotating speed of a ball milling tank is 1000 r/min.
(2) Placing the obtained mixture containing ZIFs single crystal in quartz boat, and placing in tube furnace at 4 deg.C for min-1And raising the temperature from the room temperature to 1000 ℃ for 2h, and naturally cooling to the room temperature to obtain the bamboo-shaped nitrogen-doped carbon nano tube loaded with metal monoatomic and nano-particles.
Example 4:
(1) 28mmol of 2-methylimidazole and 2mmol of Ni (NO) are added into a ball milling tank3)2·6H2O, 8mmol of hexahydrate and zinc nitrate (the mass of the reactants is 5.3g in total), and 10 grinding balls (the diameter is 0.5cm), and ball-milling is carried out for 3 hours under the condition that the rotating speed of a ball-milling tank is 1000r/min, so as to obtain a mixture containing ZIFs single crystals.
(2) Placing the obtained mixture containing ZIFs single crystal in quartz boat, and placing in tube furnace at 3 deg.C for min-1And raising the temperature from the room temperature to 800 ℃ for 3h, and naturally cooling to the room temperature to obtain the bamboo-shaped nitrogen-doped carbon nano tube loaded with metal monoatomic and nano-particles.
Example 5:
(1) 28mmol of 2-methylimidazole and 2mmol of Ni (CH) were added to a ball mill pot3COO)28mmol of hexahydrate and zinc nitrate (5.0 g in total of the reaction materials) and 10 balls (diameter: 0.5cm) were subjected to ball millingAnd ball-milling for 3h at the rotation speed of the tank of 1000r/min to obtain a mixture containing ZIFs single crystals.
(2) Placing the obtained mixture containing ZIFs single crystal in quartz boat, and placing in tube furnace at 4 deg.C for min-1And raising the temperature from the room temperature to 900 ℃ for 2h, and naturally cooling to the room temperature to obtain the bamboo-shaped nitrogen-doped carbon nano tube loaded with metal monoatomic atoms and nano particles.
In conclusion, the invention designs and prepares the mixture containing the ZIFs single crystals, and prepares the bamboo-shaped nitrogen-doped carbon nano tube loaded with metal single atoms and nano particles by adopting high-temperature pyrolysis. The carbon nano tube not only has a bamboo-shaped structure, but also has high-activity metal monoatomic atoms, so that the material has great potential application value. Meanwhile, the method has simple preparation process and is easy for large-scale production.
The invention is not the best known technology.