CN1150997C - Method for coating mono-metal particles on carbon nano tube surface - Google Patents

Abstract

The invention discloses a method for loading nanometer single metal particles on the surface of carbon nanotubes. These metals are Pt, Pd, Ru, Au or Ag. It is to uniformly disperse carbon nanotubes in a metal salt polyol solution, and then use microwave radiation to heat the uniform mixture of carbon nanotubes and metal salt polyol solution; every 1 liter of metal salt polyol solution contains 0.2 ～8 grams of carbon nanotubes; the concentration of metal salt in the metal salt polyol solution is 0.0002～0.03 mol/liter; the loading capacity of metal particles on the surface of carbon nanotubes is 5%～42%. The advantage of the present invention is that the metal nanoparticles loaded on the surface of carbon nanotubes have a small particle size, with an average particle size of 3 to 4 nanometers, and a narrow particle size distribution; the present invention also has the advantages of fast, simple and high efficiency . This carbon nanotube-loaded metal nanoparticle material has a wide range of applications in the fields of electrochemical energy conversion and catalysis.

Description

Method for supporting nano single metal particles on the surface of carbon nanotubes

Technical field

The invention relates to the preparation of nanometer metal particles, in particular to a method for loading nanometer single metal particles on the surface of carbon nanotubes.

Background technique

Carbon nanotubes have excellent physical and chemical properties due to their unique structure, and are widely used. The nanotubular structure of carbon nanotubes makes it a new catalyst carrier. For example, metal particles such as Pt and Ru loaded on the surface of carbon nanotubes have good catalytic performance. The loading behavior of metals on the surface of carbon nanotubes can be improved by oxidizing the surface of carbon nanotubes with nitric acid or a mixed acid of sulfuric acid and nitric acid. However, the previous loading method still adopts the general immersion-reduction technology, that is, the treated carbon nanotubes are first soaked in a solution containing metal salts, so that the metal salts are adsorbed on the surface of the carbon nanotubes (and some of them enter the carbon nanotubes). The inner tube of the tube), and then reduce it at high temperature in a reducing atmosphere. In addition, vapor deposition and electroless plating can also be used to coat metal nanoparticles or nanofilms on the surface of carbon nanotubes. However, these methods are difficult to control the size of metal particles loaded on the surface of carbon nanotubes, and the distribution is relatively wide. For example, literature [1] reported that the average particle diameters of Pd, Pt, Ag, and Au particles loaded on the surface of carbon nanotubes by soaking-reduction technology were 7, 8, 17, and 8 nm, respectively, and the particle size distribution was 2-12 nm. The performance of the catalyst is greatly affected by the size and uniformity of the metal nanoparticles. Generally, the smaller and more uniform the particle size, the better the catalytic performance. Therefore, how to load nano metal particles with smaller and more uniform size on the surface of carbon nanotubes has practical application value.

The polyol solution containing metal salt is heated to reflux, and the polyol acts as a reducing agent at high temperature to reduce the metal ions in the solution to form nanoparticles. This polyol process is used to load nano metal particles on the surface of carbon nanotubes. Its typical process is to heat and reflux the mixture of ethylene glycol solution containing noble metal salts and carbon nanotubes, and the reducing agent produced by ethylene glycol at high temperature can reduce the metal ions and load them on the surface of carbon nanotubes. But this traditional heating and reflux takes 1-3h, and it is not easy to control the size of the final nanoparticles.

literature

[1] Xue B, Chen P, Hong Q, Lin JY, Tan KL, Growth of Pd, Pt, Ag and Aunanoparticles on carbon nanotubes, JOURNAL OF MATERIALS CHEMISTRY11(9): 2378-2381 2001.

Contents of Invention

The purpose of the present invention is to provide a method for loading nano single metal particles on the surface of carbon nanotubes.

It is to uniformly disperse carbon nanotubes in a metal salt polyol solution, and then use microwave radiation to heat the uniform mixture of the carbon nanotubes and the metal salt polyol solution. The polyol solution of per 1 liter of metal salt contains 0.2 to 8 grams of carbon nanotubes; the concentration of metal salt in the metal salt polyol solution is 0.0002 to 0.03 mol/liter; the metal salt is: chloroplatinic acid, potassium chloroplatinate, Platinum acetate, ruthenium chloride, chloroauric acid, silver nitrate, palladium chloride = or palladium acetate; correspondingly, the metal loaded on the carbon nanotube is: Pt, Pd, Ru, Au = or Ag; the polyol is ethyl diol.

The invention has the advantages that the Pt, Pd, Ru, Au or Ag metal nano particles loaded on the surface of the carbon nanotubes have a fine particle size, an average particle size of 3-4 nanometers, and a narrow particle size distribution. The loading amount of the metal particle on the surface of the carbon nanotube is 5%-42%. The invention also has the advantages of quickness, simplicity and high efficiency. This carbon nanotube-loaded metal nanoparticle material has a wide range of applications in the fields of electrochemical energy conversion and catalysis.

Detailed ways

The above metal salts are: chloroplatinic acid, potassium chloroplatinate, platinum acetate, ruthenium chloride, chloroauric acid, silver nitrate, palladium chloride or palladium acetate; polyhydric alcohol is ethylene glycol; carbon nanotubes are multi-walled carbon nano tubes or single-walled carbon nanotubes.

Example 1:

0.08 g of multi-walled carbon nanotubes were uniformly dispersed in 50 ml of ethylene glycol solution containing 0.0001 mole of chloroplatinic acid, and heated under 700 watts of microwave radiation for 1 minute. The average particle diameter of the platinum particles is 3.5nm, and the particle size distribution is between 2-4nm. The loading capacity of the platinum metal nanoparticles on the surface of the carbon nanotubes is 19%. However, the average particle size of the nano-platinum particles supported by carbon nanotubes prepared by the traditional soaking-reduction method is 7.6nm, and the particle size distribution is between 2-11nm.

Example 2:

Uniformly disperse 0.01 g of single-walled carbon nanotubes in 50 ml of ethylene glycol solution containing 0.00001 moles of platinum acetate, and heat for 1 minute under 700 watts of microwave radiation. The nano-platinum loaded on the surface of carbon nanotubes was observed by transmission electron microscopy The average particle diameter of the particles is 3.3nm, the particle size distribution is between 2-4nm, and the loading amount of the platinum metal nanoparticles on the surface of the carbon nanotube is 16%. However, the average particle size of the nano-platinum particles supported by carbon nanotubes prepared by the traditional soaking-reduction method is 6.6nm, and the particle size distribution is between 1-9nm.

Example 3:

0.4 grams of multi-walled carbon nanotubes were uniformly dispersed in 50 ml of ethylene glycol solution containing 0.0015 moles of potassium chloroplatinate, and heated for 1 minute under 700 watts of microwave radiation. The average particle diameter of the nano-platinum particles is 3.6nm, the particle size distribution is between 2-4nm, and the loading amount of the platinum metal nanoparticles on the surface of the carbon nanotube is 42%. However, the average particle size of the nano-platinum particles supported by carbon nanotubes prepared by the traditional soaking-reduction method is 7.8nm, and the particle size distribution is between 1-13nm.

Example 4:

0.02 g of multi-walled carbon nanotubes were uniformly dispersed in 50 ml of ethylene glycol solution containing 0.00005 moles of ruthenium chloride, and heated under 700 watts of microwave radiation for 1 minute. The carbon nanotubes loaded on the surface of the carbon nanotubes were observed by a transmission electron microscope. The average particle size of the ruthenium particles is 3.2nm, the particle size distribution is between 2-4nm, and the loading amount of the ruthenium metal nanoparticles on the surface of the carbon nanotube is 20%. However, the average particle size of the nano-ruthenium particles supported by carbon nanotubes prepared by the traditional soaking-reduction method is 6.1 nm, and the particle size distribution is between 1-9 nm.

Example 5:

0.09 grams of multi-walled carbon nanotubes were uniformly dispersed in 50 ml of ethylene glycol solution containing 0.00005 moles of palladium acetate, and heated for 1 minute under 700 watts of microwave radiation. The nano-palladium loaded on the surface of carbon nanotubes was observed by transmission electron microscopy The average particle size of the particles is 3.8nm, the particle size distribution is between 2-4.2nm, and the loading amount of the palladium metal nanoparticles on the surface of the carbon nanotube is 5.5%. However, the average particle diameter of the nano-palladium particles supported by carbon nanotubes prepared by the traditional soaking-reduction method is 6.8nm, and the particle size distribution is between 1-12.3nm.

Embodiment 6:

0.09 g of multi-walled carbon nanotubes were uniformly dispersed in 50 ml of ethylene glycol solution containing 0.00005 moles of chloroauric acid, and heated under 700 watts of microwave radiation for 1 minute. The nanometers loaded on the surface of carbon nanotubes were observed by transmission electron microscopy. The average particle size of the gold particles is 3.5nm, the particle size distribution is between 2-4nm, and the loading amount of the metal nanoparticle on the surface of the carbon nanotube is 10%. However, the average particle size of the carbon nanotube-loaded nano gold particles prepared by the traditional soaking-reduction method is 7.6nm, and the particle size distribution is between 2-11nm.

Embodiment 7:

0.04 g of multi-walled carbon nanotubes were uniformly dispersed in 50 ml of ethylene glycol solution containing 0.00005 moles of silver nitrate, and heated under 700 watts of microwave radiation for 1 minute. The average particle diameter of the silver nanoparticles loaded on the surface of the carbon nanotubes was observed by a transmission electron microscope, and the particle diameter was distributed between 2-4nm. The loading amount of the silver metal nanoparticles on the surface of the carbon nanotubes was 11%. However, the average particle size of the carbon nanotube-loaded nano-silver particles prepared by the traditional soaking-reduction method is 6.0 nm, and the particle diameter is distributed between 1-9 nm.

Claims (2)

1. A method for loading nanometer single metal particles on the surface of carbon nanotubes, characterized in that carbon nanotubes are uniformly dispersed in metal salt polyol solution, then microwave radiation is used to heat the carbon nanotube and metal salt polyol solution Uniform mixture; every 1 liter of metal salt polyol solution contains 0.2 to 8 grams of carbon nanotubes; the concentration of metal salt in the metal salt polyol solution is 0.0002 to 0.03 mol/liter, and the metal salts are: chloroplatinic acid, chlorine Potassium platinate, platinum acetate, ruthenium chloride, chloroauric acid, silver nitrate, palladium chloride or palladium acetate; corresponding metals supported on carbon nanotubes are: Pt, Pd, Ru, Au or Ag, polyol for ethylene glycol. 2. A method for loading nano single metal particles on the surface of carbon nanotubes according to claim 1, characterized in that said carbon nanotubes are: multi-walled carbon nanotubes or single-walled carbon nanotubes.