A method for preparing carbon nanotube-supported metal monatomic atoms by flame reduction
The method of preparing carbon nanotube-supported metal single atoms by flame reduction at room temperature and atmospheric pressure solves the problems of cumbersome preparation process and poor stability of single-atom catalysts, and realizes rapid and simple preparation and efficient application of single-atom materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING UNIV OF CHEM TECH
- Filing Date
- 2021-01-22
- Publication Date
- 2026-05-29
Smart Images
Figure CN112916865B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of metal single-atom preparation technology, specifically relating to a method for preparing carbon nanotube-supported metal single atoms using flame reduction. Background Technology
[0002] With the depletion of energy resources and the increasing severity of environmental problems, the development of renewable clean energy conversion technologies (fuel cells, metal-air cells, and water electrolysis) is urgently needed. The core of clean energy conversion technology lies in a series of electrochemical reactions at two electrodes, and the smooth progress of these reactions depends on the participation of highly active and stable catalysts. Therefore, the rational design of electrocatalyst materials with excellent activity and stability is crucial for accelerating electrode reactions and promoting the commercialization of clean energy conversion technologies.
[0003] In recent years, single-atom catalysts have attracted widespread attention due to their high reactivity, selectivity, and 100% atom utilization. Their high activity stems from the unsaturated coordination of the active center atoms, the support effect, and the quantum size effect. Furthermore, the catalytic mechanism of single-atom catalysts is easier and more readily understood. However, the cumbersome preparation process and poor stability limit the large-scale application of single-atom catalysts. Currently, commonly used methods for preparing single-atom catalysts include wet chemical methods, pyrolysis methods, electrochemical methods, and physical deposition methods. These methods not only require stringent operating conditions but also have preparation cycles that can range from several hours to several days. Therefore, how to rapidly prepare single-atom materials has become a current research hotspot. Summary of the Invention
[0004] To overcome the problems existing in the current single-atom preparation technology, the present invention provides a method for preparing carbon nanotubes (CNTs) loaded with metal single atoms using flame reduction.
[0005] The method for preparing carbon nanotube-loaded metal single atoms by flame reduction according to the present invention is as follows: first, the support is pretreated; after drying, the support is placed in a flame for flame reduction to prepare a carbon nanotube array; then, the support is immersed in a metal precursor solution, taken out and dried, and then placed in a flame for flame reduction to prepare carbon nanotube-loaded metal single atoms.
[0006] The carbon nanotubes loaded with metal single atoms prepared above were repeatedly immersed in a metal precursor solution and subjected to flame reduction to increase the loading of metal single atoms.
[0007] The carrier is nickel foam, nickel foil, or nickel mesh.
[0008] The method for pretreating the carrier is as follows: the carrier is sequentially immersed in hydrochloric acid, acetone, ethanol and deionized water for ultrasonic cleaning.
[0009] The flame is the inner flame of an alcohol lamp.
[0010] The fire exposure time is 1-30 minutes.
[0011] The solvent for the metal precursor solution is water, methanol, or ethanol, with a concentration of 0.1 mg / mL. -1 -1g mL -1 Soaking time is 1-60 minutes.
[0012] The metal is one or more of cobalt, iron, nickel, copper, manganese, zinc, silver, platinum, palladium, and gold.
[0013] The metal precursor is one or more compounds containing cobalt, iron, nickel, copper, manganese, zinc, silver, platinum, palladium, and gold.
[0014] The metal precursor is one or more of the following: cobalt salt, iron salt, ferrous salt, nickel salt, copper salt, manganese salt, zinc salt, silver salt, platinum salt, palladium salt, and gold salt.
[0015] The inner flame of an alcohol lamp, due to its low temperature, contains many incompletely burned carbon-containing organic molecules, thus possessing a certain reducing property. Nickel is a type of metal that can catalyze the growth of carbon nanotubes. Therefore, during the first burning process in the inner flame of the alcohol lamp, the carbon-containing organic molecules volatilize and adhere to the support, and under the catalysis of nickel, carbon nanotubes are generated in situ on the support. Subsequently, they are immersed in a metal precursor solution to adsorb metal ions, dried, and then burned a second time. Due to the reducing property of the inner flame of the alcohol lamp, the adsorbed metal ions are reduced to metal single atoms, resulting in carbon nanotube-supported metal single-atom materials.
[0016] This invention addresses the problems of cumbersome and unstable single-atom catalyst preparation processes by providing a simple method for preparing carbon nanotube-supported metal single atoms. This preparation process avoids the high temperature, high pressure, long time, and high cost involved in traditional single-atom catalyst preparation. The entire preparation process is carried out at room temperature and atmospheric pressure, and the preparation cycle can be controlled within one hour, making it rapid, simple, and universally applicable. Attached Figure Description
[0017] Figure 1 These are scanning electron microscope images of the CNT array obtained in Embodiment 1 of the present invention at different magnifications, with insets being digital photographs;
[0018] Figure 2 These are scanning electron microscope (SEM) images and aberration-corrected scanning transmission electron microscope (STEM) images of CNT-loaded cobalt single atoms prepared in Example 1 of this invention.
[0019] Figure 3 This is the X-ray photoelectron spectrum of the CNT-loaded cobalt single atom prepared in Example 1 of this invention;
[0020] Figure 4These are scanning electron microscope images and elemental distribution diagrams of CNT-loaded platinum single atoms obtained in Example 2 of this invention. Detailed Implementation
[0021] The preparation of CNT-loaded metal single atoms by flame reduction method according to the present invention will be described in detail below with reference to the accompanying drawings and embodiments.
[0022] Example 1
[0023] CNT-loaded cobalt single atoms
[0024] Using nickel foam (5cm*5cm) as a carrier, the nickel foam was ultrasonically cleaned sequentially in 2M hydrochloric acid, acetone, ethanol, and deionized water for 30 minutes, then removed and air-dried. The treated nickel foam was then subjected to repeated heating in the inner flame of an alcohol lamp for 10 minutes until the surface turned black, resulting in a CNT array. A 3mg mL solution was prepared. -1 A cobalt nitrate ethanol solution was used to immerse a CNT array in the solution for 10 minutes, followed by air drying to obtain a CNT array adsorbed with cobalt ions. The CNT array adsorbed with cobalt ions was then subjected to repeated flame treatment in parallel within an alcohol lamp for 10 minutes to obtain CNT-loaded cobalt single atoms. This immersion in the cobalt nitrate ethanol solution and flame treatment was repeated twice to increase the loading of cobalt single atoms.
[0025] Morphological characterization of CNTs, Figure 1 The image shows a scanning electron microscope (SEM) image. As can be seen from the image, the prepared CNTs exhibit an array structure and are uniformly and densely loaded on the surface of nickel foam.
[0026] Morphological characterization of CNT-loaded cobalt single atoms, Figure 2 Images (a and b) are scanning electron microscope (SEM) images, and (c and d) are aberration-corrected scanning transmission electron microscope (STEM) images. Images (a and b) show that the CNT-loaded cobalt single atoms maintain a well-preserved nanowire array structure, with no particles present on the surface. Images (c and d) show numerous dense white bright spots dispersed on the CNTs, which are the cobalt single atoms.
[0027] Structural characterization of CNT-loaded cobalt single atoms, Figure 3 This is X-ray photoelectron spectroscopy. For cobalt nitrate adsorbed on CNTs, the appearance of an MO bond in the 1s O after flame reduction indicates that cobalt successfully binds to O in the CNTs. The decrease in the 2p1 / 2 and 2p3 / 2 binding energies of Co indicates that the high-valence cobalt ions adsorbed on the CNTs are reduced to low-valence cobalt.
[0028] Example 2
[0029] CNT-supported platinum single atoms
[0030] Using nickel foam (5cm*5cm) as a carrier, the nickel foam was ultrasonically cleaned sequentially in 2M hydrochloric acid, acetone, ethanol, and deionized water for 30 minutes, then removed and allowed to air dry. The treated nickel foam was then subjected to repeated heating in the inner flame of an alcohol lamp for 10 minutes until the surface turned black, resulting in a CNT array. A 1mg mL solution was prepared... -1 A potassium chloroplatinate aqueous solution was used to immerse the CNT array in the solution for 1 minute, then remove and air dry to obtain a CNT array adsorbed with platinum ions. The platinum-adsorbed CNT array was then subjected to repeated flame treatment with an alcohol lamp for 10 minutes to obtain CNT-loaded platinum single atoms. This immersion-flame treatment was repeated twice to increase the platinum single-atom loading.
[0031] Morphological characterization of platinum single atoms supported on CNTs. Figure 4 The images show the scanning electron microscope (SEM) image and elemental distribution map of platinum single atoms supported on CNTs. As can be seen from the images, the platinum single atoms supported on CNTs maintain a well-structured nanowire array, with no particles present on the surface. The elemental distribution map shows that C, O, and Pt are uniformly dispersed on the material surface.
[0032] Example 3
[0033] CNT-supported nickel single-atom
[0034] Using nickel foam (5cm*5cm) as a carrier, the nickel foam was ultrasonically cleaned sequentially in 2M hydrochloric acid, acetone, ethanol, and deionized water for 30 minutes, then removed and allowed to air dry. The treated nickel foam was then subjected to repeated heating in the inner flame of an alcohol lamp for 10 minutes until the surface turned black, resulting in a CNT array. A 5mg mL solution was prepared. -1 A nickel nitrate ethanol solution was used to immerse the CNT array in the solution for 5 minutes, then remove and air dry to obtain a CNT array adsorbed with nickel ions. The CNT array adsorbed with nickel ions was then subjected to a back-and-forth flame treatment in parallel within an alcohol lamp for 10 minutes to obtain CNT-loaded nickel single atoms. This immersion-heat treatment step was repeated twice to increase the loading of nickel single atoms.
[0035] Example 4
[0036] CNT-loaded iron single atoms
[0037] Using nickel foam (5cm*5cm) as a carrier, the nickel foam was ultrasonically cleaned sequentially in 2M hydrochloric acid, acetone, ethanol, and deionized water for 30 minutes, then removed and air-dried. The treated nickel foam was then subjected to repeated heating in the inner flame of an alcohol lamp for 10 minutes until the surface turned black, resulting in a CNT array. A 20mg mL solution was prepared. -1A CNT array was immersed in a ferric nitrate ethanol solution for 10 minutes, then removed and air-dried to obtain a CNT array adsorbed with iron ions. The iron-adsorbed CNT array was then subjected to repeated heat treatment in the inner flame of an alcohol lamp for 10 minutes to obtain CNT-loaded iron single atoms.
Claims
1. A method for preparing carbon nanotubes loaded with metal single atoms using flame reduction, characterized in that, The method is as follows: First, the carrier is pretreated; after drying, the carrier is placed in a flame for reduction to prepare a carbon nanotube array; then the carrier is immersed in a metal precursor solution, taken out and dried, and then placed in a flame for reduction to prepare carbon nanotubes loaded with metal single atoms. The method for pretreating the carrier is as follows: the carrier is sequentially immersed in hydrochloric acid, acetone, ethanol and deionized water for ultrasonic cleaning. The solvent for the metal precursor solution is water, methanol, or ethanol, with a concentration of 0.1 mg / mL. -1 -1 g mL -1 Soaking time is 1-60 minutes; The carrier is nickel foam, nickel foil, or nickel mesh; The flame is the inner flame of an alcohol lamp; The fire exposure time is 1-30 minutes; The metal is one or more of cobalt, iron, nickel, copper, manganese, zinc, silver, platinum, palladium, and gold; The metal precursor is one or more compounds containing cobalt, iron, nickel, copper, manganese, zinc, silver, platinum, palladium, and gold.
2. The method according to claim 1, characterized in that, The prepared carbon nanotubes loaded with metal single atoms were repeatedly immersed in a metal precursor solution and subjected to flame reduction to increase the loading of metal single atoms.
3. The method according to claim 1, characterized in that, The metal precursor is one or more of the following: cobalt salt, iron salt, ferrous salt, nickel salt, copper salt, manganese salt, zinc salt, silver salt, platinum salt, palladium salt, and gold salt.