CN1150998C - Method for supporting platinum-ruthenium alloy nanoparticles on the surface of carbon nanotubes - Google Patents

Abstract

The present invention discloses a method for carrying platinum-ruthenium alloy nano particles on the surfaces of carbon nanotubes. The carbon nanotubes are uniformly dispersed in a polyalcohol solution simultaneously containing two kinds of metal salts of platinum and ruthenium, and then, uniform mixtures of the carbon nanotubes and the metal salts are heated by microwave radiation; each liter of polyalcohol solution of the metal salts contains 0.2 to 8.0g of carbon nanotube, and the concentration of the metal salts in the polyalcohol solution of the metal salts is from 0.0004 to 0.04 mol/l. The carried quantity of the alloy particles on the surfaces of the carbon nanotubes is from 6% to 45%, the atomic composition ratio of alloys is PtxRuy, wherein x is from 0.1 to 1, and y is from 0.1 to 1. The present invention has the advantages that the platinum-ruthenium alloy nano particles carried on the surfaces of the carbon nanotubes have small particle size, the average particle size is from 3 to 3 nm, and the particle size distribution is narrow. The present invention also has the advantages of rapidity, simplicity and high efficiency, and the platinum-ruthenium alloy nano particle materials carried on the carbon nanotubes have extensive application in the fields of electrochemical energy transfer and catalysis.

Description

Method for supporting platinum-ruthenium alloy nanoparticles on the surface of carbon nanotubes

Technical field

The invention relates to the preparation of alloy nanoparticles, in particular to a method for loading platinum-ruthenium alloy nanoparticles on the surface of carbon nanotubes.

Background technique

Carbon material supported platinum-ruthenium alloy nanoparticles have very important applications in fuel cells. Platinum-ruthenium alloy catalysts have excellent resistance to carbon monoxide poisoning than single metal platinum, so they are used as direct methanol fuel cells and fuel cells using hydrogen containing trace amounts of carbon monoxide. Important electrocatalytic electrode materials. The nanotubular structure of carbon nanotubes makes it a new catalyst carrier, and the Pt and Ru metal particles 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 general loading method in the past is soaking-reduction technology, that is, carbon nanotubes are first soaked in a solution containing metal salts, so that the metal salts are adsorbed on the surface of carbon nanotubes, and then reduced at high temperature in a reducing atmosphere. This method is difficult to control the size and uniformity of the metal particles loaded on the surface of carbon nanotubes. For example, literature [1] reported that the average particle sizes 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 metal salts and carbon nanotubes. At high temperature, the reducing agent produced by ethylene glycol reduces the metal ions and loads 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 platinum-ruthenium alloy nanoparticles on the surface of carbon nanotubes.

It is to uniformly disperse carbon nanotubes in a polyol solution containing two metal salts of platinum and ruthenium, and then use microwave radiation to heat the uniform mixture of carbon nanotubes and metal salt polyol solution; every 1 liter of metal salt The polyol solution contains 0.2 to 8.0 grams of carbon nanotubes; the concentration of the metal salt in the metal salt polyol solution is 0.0004 to 0.04 mol/liter; the atomic ratio of the alloy is Pt _x Ru _y , where X=0.1 to 1, Y =0.1～1; polyol is 7 diols.

The invention has the advantages that the platinum-ruthenium alloy nanoparticles 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 alloy particles on the surface of the carbon nanotube is 6%-45%. The invention also has the advantages of quickness, simplicity and high efficiency. The platinum-ruthenium alloy nanoparticle material supported by carbon nanotubes is widely used in the fields of electrochemical energy conversion and catalysis.

Detailed ways

One of the above two metal salts is: chloroplatinic acid, potassium chloroplatinate or platinum acetate; the other metal salt is ruthenium chloride; the carbon nanotubes are multi-walled carbon nanotubes 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 0.0001 mole of ruthenium chloride, and heated for 1 minute under 700 watts of microwave radiation. The average particle size of the nano-platinum-ruthenium alloy particles loaded on the surface of the nanometer tube is 3.4nm, and the particle size distribution is between 2nm and 4nm. The composition of the platinum-ruthenium alloy is: Pt _1.0 Ru _1.0 ; the loading amount of the platinum-ruthenium alloy on the surface of the carbon nanotube is 26%. However, the average particle size of nano-platinum-ruthenium alloy particles supported by carbon nanotubes prepared by the traditional soaking-reduction method is 6.4nm, and the particle size distribution is between 1-13nm.

Example 2:

Disperse 0.01 g of multi-walled carbon nanotubes uniformly in 50 ml of ethylene glycol solution containing 0.00001 mole of chloroplatinic acid and 0.00001 mole of ruthenium chloride, and heat under 700 watts of microwave radiation for 1 minute. The carbon The average particle size of nano-platinum-ruthenium alloy particles loaded on the surface of nanotubes is 3.1nm, and the particle diameter is distributed between 2-4nm. The composition of platinum-ruthenium alloy is: Pt _1.0 Ru _1.0 ; platinum-ruthenium alloy in carbon nanotubes The surface loading was 22%. However, the average particle size of the nano-platinum-ruthenium alloy particles supported by carbon nanotubes prepared by the traditional soaking-reduction method is 6.0 nm, and the particle size distribution is between 1 and 10 nm.

Example 3:

0.4 g of multi-walled carbon nanotubes were uniformly dispersed in 50 ml of ethylene glycol solution containing 0.0001 mole of chloroplatinic acid and 0.0001 mole of ruthenium chloride, and heated under 700 watts of microwave radiation for 1 minute. The carbon The average particle size of nano-platinum-ruthenium alloy particles loaded on the surface of nanotubes is 3.5nm, and the particle diameter is distributed between 2-4nm. The composition of platinum-ruthenium alloy is: Pt _1.0 Ru _1.0 ; The surface loading was 6.9%. However, the average particle size of the nano-platinum-ruthenium alloy particles supported by carbon nanotubes prepared by the traditional soaking-reduction method is 7.4 nm, and the particle size distribution is between 1 and 12 nm.

Example 4:

0.4 g of multi-walled carbon nanotubes were uniformly dispersed in 50 ml of ethylene glycol solution containing 0.001 mole of chloroplatinic acid and 0.001 mole of ruthenium chloride, and heated under 700 watts of microwave radiation for 1 minute. The average particle size of nano-platinum-ruthenium alloy particles loaded on the surface of nanotubes is 3.6nm, and the particle diameter is distributed between 2 and 5nm. The composition of platinum-ruthenium alloy is: Pt _1.0 Ru _1.0 ; platinum-ruthenium alloy in carbon nanotubes The surface loading was 42%. However, the average particle size of the nano-platinum-ruthenium alloy particles supported by carbon nanotubes prepared by the traditional soaking-reduction method is 7.4 nm, and the particle size distribution is between 1 and 15 nm.

Example 5:

0.08 grams of single-walled carbon nanotubes were uniformly dispersed in 50 ml of ethylene glycol solution containing 0.0001 moles of potassium chloroplatinate and 0.00001 moles of ruthenium chloride, and heated for 1 minute under 700 watts of microwave radiation. Transmission electron microscope observation The average particle size of nano-platinum-ruthenium alloy particles loaded on the surface of carbon nanotubes is 3.3nm, and the particle size distribution is between 2 and 4nm. The composition of platinum-ruthenium alloy is: Pt _1.0 Ru _1.0 ; platinum-ruthenium alloy in carbon nanotubes The loading of the surface is 20%. However, the average particle size of nano-platinum-ruthenium alloy particles supported by carbon nanotubes prepared by the traditional soaking-reduction method is 5.4 nm, and the particle size distribution is between 1 and 11 nm.

Embodiment 6:

0.08 grams of single-walled carbon nanotubes were uniformly dispersed in 50 ml of ethylene glycol solution containing 0.00001 moles of platinum acetate and 0.0001 moles of ruthenium chloride, and heated under 700 watts of microwave radiation for 1 minute. The carbon nanotubes were observed by transmission electron microscope The average particle size of the nano-platinum-ruthenium alloy particles loaded on the surface of the tube is 3.3nm, and the particle diameter is distributed between 2-4nm. The composition of the platinum-ruthenium alloy is: Pt _0.1 Ru _1.0 ; the platinum-ruthenium alloy on the surface of the carbon nanotube The loading is 13%. However, the average particle size of the nano-platinum-ruthenium alloy particles supported by carbon nanotubes prepared by the traditional soaking-reduction method is 5.4nm, and the particle size distribution is between 1 and 11nm.

Claims (3)

1. A method of supporting platinum-ruthenium alloy nanoparticles on the surface of carbon nanotubes, characterized in that carbon nanotubes are uniformly dispersed in a polyol solution containing two metal salts of platinum and ruthenium, and then heated by microwave radiation The homogeneous mixture of the carbon nanotubes and the metal salt polyol solution; every 1 liter of the metal salt polyol solution contains 0.2 to 8.0 grams of carbon nanotubes; the concentration of the metal salt in the metal salt polyol solution is 0.0004 to 0.04 mol/liter ; The atomic ratio of the alloy is Pt _x Ru _y , where X=0.1-1, Y=0.1-1; the polyhydric alcohol is ethylene glycol. 2. a kind of method of carrying platinum-ruthenium alloy nanoparticle on carbon nanotube surface according to claim 1, it is characterized in that wherein a kind of metal salt of said two kinds of metal salts is: chloroplatinic acid, chloroplatinum Potassium acetate or platinum acetate; another metal salt is ruthenium chloride. 3. A method for loading platinum-ruthenium alloy nanoparticles on the surface of carbon nanotubes according to claim 1, characterized in that the carbon nanotubes are multi-walled carbon nanotubes or single-walled carbon nanotubes.