CN105845948B - A kind of preparation method of flower-shaped copper/cupric oxide Micron-nano composites carried noble metal fuel-cell catalyst - Google Patents

Abstract

The invention discloses a preparation method of a flower-shaped copper/copper oxide micro-nano composite material loaded noble metal fuel cell catalyst, which belongs to the technical field of synthesis of fuel cell catalysts. The key points of the technical scheme of the present invention are: using copper chloride as the copper source, glucose as the carbon source, cetyltrimethylammonium bromide as the surfactant and structure-directing agent, deionized water as the solvent, and hydrothermally synthesizing flower Shaped copper/copper oxide micro-nano composite material, and then the flower-shaped copper/copper oxide micro-nano composite material is functionalized and then reacted with the noble metal precursor under the action of a reducing agent to obtain the target product. The copper oxide of the present invention can be used as a transition metal oxide to improve the activity of the noble metal catalyst through the catalytic effect, reduce the consumption of the noble metal, and reduce the cost of the fuel cell catalyst; the simple copper in the carrier and the copper oxide form a composite material, and the addition of copper effectively enhances the The electronic conductivity of the material improves the problem of poor conductivity of transition metal oxides.

Description

A flower-like copper/copper oxide micro-nanocomposite material loaded noble metal fuel cell catalyst Chemical preparation method

technical field

The invention belongs to the technical field of synthesis of fuel cell catalysts, and in particular relates to a method for preparing a flower-like copper/copper oxide micro-nano composite material loaded noble metal fuel cell catalyst.

Background technique

Proton exchange membrane fuel cell (PEMFC) is a clean energy source with renewable fuel, wide sources, safe storage and environmental friendliness. In proton exchange membrane fuel cells, the catalyst is the core component and the key material that determines the cost and performance of the cell. Common supports for fuel cell catalysts include carbon black (XC-72), carbon nanotubes (MWCNTs) and mesoporous carbon supports. Carbon black is one of the catalyst supports widely used at present, but its corrosion resistance is weak and its stability is poor; The characteristics make some catalyst metal nanoparticles may be coated in the pores, resulting in a decrease in the utilization rate of the catalyst. Therefore, the development of a new carrier that can improve the catalyst activity has become one of the important problems to be solved in the technical field of fuel cell catalyst synthesis.

In recent years, research on transition metal oxides as catalyst supports and cocatalysts for direct alcohol fuel cells (DAFC) has emerged in an endless stream. The main reason is that: on the one hand, transition metal oxides can improve the activity of noble metal catalysts by promoting the catalytic effect, reduce the amount of noble metals, and then reduce the cost of fuel cell catalysts; on the other hand, transition metal oxides can improve the electrochemical stability of catalysts. , prolong the catalytic life. However, there is currently no relevant report on the preparation method of flower-shaped copper/copper oxide micro-nanocomposites supporting noble metal fuel cell catalysts.

Contents of the invention

The technical problem solved by the invention is to provide a preparation method of flower-shaped copper/copper oxide micro-nano composite material loaded noble metal fuel cell catalyst, which effectively improves the performance of the fuel cell catalyst.

In order to solve the above technical problems, the present invention adopts the following technical scheme, a preparation method of a flower-shaped copper/copper oxide micro-nano composite material loaded noble metal fuel cell catalyst, which is characterized in that the specific steps are:

(1) Using copper chloride as copper source, glucose as carbon source, cetyltrimethylammonium bromide as surfactant and structure-directing agent, deionized water as solvent, hydrothermal reaction at 150-200℃ for 9 -48h, the product was washed with deionized water and absolute ethanol and then dried to obtain a black powder product;

(2) Place the black powder product obtained in step (1) in a tube furnace and calcinate at 800°C for 3 hours, then take out the sample and disperse it in an alkali solution with a molar concentration of 0.5-3mol/L, heat it under reflux for 1-5 hours, and wait for the reaction Cool and wash with deionized water to neutrality after the end, and obtain flower-shaped copper/copper oxide composite carrier after drying;

(3) Ultrasonic disperse the flower-shaped copper/copper oxide composite carrier obtained in step (2) and sodium citrate in a hydroalcoholic solution, then add a noble metal precursor and adjust the pH of the reaction system to 10, and then add a reducing agent to reduce After washing and drying, the flower-shaped copper/copper oxide micro-nanocomposite material supported noble metal fuel cell catalyst is obtained, wherein the noble metal precursor is one or more of H ₂ PtCl ₆ , Na ₂ PdCl ₄ , RuCl ₃ or RhCl ₃ , and the reduction The agent is KBH ₄ , NaBH ₄ , ascorbic acid, hydrazine hydrate, H ₂ or CO.

Further preferably, the mass ratio of copper chloride to glucose is 1:10-10:1, and the mass ratio of copper chloride to cetyltrimethylammonium bromide is 1:20-20:1.

Further preferably, the alkaline solution is potassium hydroxide solution, sodium hydroxide solution or ammonia solution.

Further preferably, the shape of the flower-shaped copper/copper oxide composite carrier is a multi-dimensional radial flower structure with a size of 1-5 μm.

Further preferably, the noble metal active component is Pt, Pd, PtPd, PtRu, PtRh, PdRu or PdRh.

Further preferably, the volume ratio of water to alcohol in the hydroalcoholic solution is 1:1, and the alcohol is specifically methanol, ethanol or propanol.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention synthesized the flower-like copper/copper oxide micro-nano composite material as a fuel cell catalyst carrier for the first time. The synthesis method is simple to operate and has a high yield;

2. The flower-like copper/copper oxide micro-nano composite material synthesized by the present invention has a flower-like special structure, which plays a favorable role in the uniform loading of the noble metal catalyst, prevents the agglomeration of noble metal nanoparticles, and thus effectively improves the catalytic performance. catalytic activity;

3. The flower-shaped copper/copper oxide micro-nano composite material synthesized by the present invention has a large specific surface area and strong electrical conductivity, which is conducive to mass transfer and current conduction in the electrolyte;

4. In the flower-shaped copper/copper oxide micro-nano composite material synthesized by the present invention, copper oxide is used as a transition metal oxide, and the oxygen-containing groups on its surface effectively weaken the poisoning effect of carbon monoxide on the catalyst. The flower-shaped copper/copper oxide The copper in the copper micro-nano composite material improves the conductivity of the carrier, and plays a good role in surface modification, effectively improving the dispersion degree of the catalyst and enhancing the electrochemical activity.

Description of drawings

Fig. 1 is the SEM picture of the flower-shaped copper/copper oxide composite support that the embodiment of the present invention 1 makes;

Fig. 2 is the XRD spectrum of the flower-shaped copper/copper oxide composite carrier that the embodiment 1 of the present invention makes;

Fig. 3 is a comparison of the electrochemical cyclic voltammetry test curves of the Pt catalysts prepared in Example 1 of the present invention and Comparative Example 1 and Comparative Example 2.

detailed description

The above-mentioned contents of the present invention are described in further detail below through the embodiments, but this should not be interpreted as the scope of the above-mentioned themes of the present invention being limited to the following embodiments, and all technologies realized based on the above-mentioned contents of the present invention all belong to the scope of the present invention.

Example 1

Take 3g cupric chloride, 1g glucose and 1g hexadecyltrimethylammonium bromide dissolved in 30mL deionized water to make a solution, then hydrothermally react at 160°C for 36h, and pass the product through deionized water and absolute ethanol Wash several times and dry to obtain a black powder product; place the obtained black powder product in a tubular atmosphere furnace and calcinate at 800°C for 3 hours, then take an appropriate amount of sample and disperse it in a sodium hydroxide solution with a molar concentration of 2mol/L Heat and reflux in a medium-boiling water bath for 3 hours to functionalize its surface. After the reaction is completed, it is cooled and washed with deionized water to neutrality. After drying, a black powder sample is obtained, which is a flower-shaped copper/copper oxide composite carrier; take 40 mg flower Shaped copper/copper oxide composite carrier and 100 mg sodium citrate were ultrasonically dispersed in a water/ethanol mixture with a volume ratio of 1:1, and then 10 mL of noble metal precursor H ₂ PtCl ₆ was added to adjust the pH of the reaction system to 10, and then After adding KBH ₄ for reduction, it was washed with deionized water and dried in a vacuum oven at 40°C to finally obtain the black target product. It can be seen from Fig. 1 that the target product prepared in this embodiment is a flower-like structure with a uniform appearance and a diameter of about 3 μm.

Example 2

Take 2g of copper chloride, 1g of glucose and 1.5g of hexadecyltrimethylammonium bromide dissolved in 30mL of deionized water to make a solution, and then conduct a hydrothermal reaction at 180°C for 24h, and pass the product through deionized water and anhydrous Wash with ethanol several times and dry to obtain a black powder product; place the obtained black powder product in a tube-type atmosphere furnace and calcinate at 800°C for 3 hours, then take an appropriate amount of sample and disperse it in sodium hydroxide with a molar concentration of 3mol/L Heat and reflux in a boiling water bath for 2 hours in the solution to functionalize the surface. After the reaction is completed, it is cooled and washed with deionized water to neutrality. After drying, a black powder sample is obtained, which is a flower-shaped copper/copper oxide composite carrier; take 40mg The flower-shaped copper/copper oxide composite carrier and 100 mg of sodium citrate were ultrasonically dispersed in a water/ethanol mixture with a volume ratio of 1:1, and then 10 mL of the noble metal precursor H ₂ PtCl ₆ was added and the pH of the reaction system was adjusted to 10. After adding KBH ₄ for reduction, it was washed with deionized water and dried in a vacuum oven at 40°C to obtain a black target product. It can be seen from Figure 2 that the target product prepared in this example has a copper/copper oxide composite structure, no impurity peaks appear, and the sharp diffraction peaks indicate better crystallinity.

Example 3

Take 20g cupric chloride, 5g glucose and 1g hexadecyltrimethylammonium bromide dissolved in 30mL deionized water to make a solution, then hydrothermally react at 200°C for 18h, and pass the product through deionized water and absolute ethanol Wash several times and dry to obtain a black powder product; place the obtained black powder product in a tubular atmosphere furnace and calcinate at 800°C for 3 hours, then take an appropriate amount of sample and disperse it in a boiling water bath with a molar concentration of 2mol/L ammonia solution Heat to reflux for 4 hours, functionalize its surface, wash with deionized water to neutrality after the reaction is completed, and obtain a black powder sample after drying, which is a flower-shaped copper/copper oxide composite carrier; take 40 mg flower-shaped copper/copper oxide The copper oxide composite carrier and 100 mg of sodium citrate were ultrasonically dispersed in a water/propanol mixture with a volume ratio of 1:1, then 10 mL of the noble metal precursor Na ₂ PdCl ₄ was added to adjust the pH of the reaction system to 10, and then KBH ₄ After reduction, wash with deionized water and dry in a vacuum oven at 40°C to finally obtain the black target product.

Example 4

Dissolve 6g of copper chloride, 1g of glucose and 2g of cetyltrimethylammonium bromide in 30mL of deionized water to form a solution, then conduct a hydrothermal reaction at 160°C for 18h, and pass the product through deionized water and absolute ethanol Wash several times and dry to obtain a black powder product; place the obtained black powder product in a tubular atmosphere furnace and calcinate at 800°C for 3 hours, then take an appropriate amount of sample and disperse it in a sodium hydroxide solution with a molar concentration of 1mol/L Heat and reflux in a medium-boiling water bath for 3 hours to functionalize its surface. After the reaction is completed, it is cooled and washed with deionized water to neutrality. After drying, a black powder sample is obtained, which is a flower-shaped copper/copper oxide composite carrier; take 40 mg flower Shaped copper/copper oxide composite carrier and 100 mg sodium citrate were ultrasonically dispersed in a water/ethanol mixed solution with a volume ratio of 1:1, then 5 mL of noble metal precursor H ₂ PtCl ₆ and 5 mL of noble metal precursor Na ₂ PdCl ₄ were added and Adjust the pH of the reaction system to 10, then add KBH ₄ for reduction, wash with deionized water and put it in a vacuum drying oven at 40°C to dry, finally the black target product is obtained.

Example 5

Take 5g cupric chloride, 3g glucose and 5g hexadecyltrimethylammonium bromide dissolved in 30mL deionized water to make a solution, then hydrothermally react at 150°C for 48h, and pass the product through deionized water and absolute ethanol Wash several times and dry to obtain a black powder product; place the obtained black powder product in a tubular atmosphere furnace and calcinate at 800°C for 3 hours, then take an appropriate amount of sample and disperse it in sodium hydroxide with a molar concentration of 0.5mol/L Heat and reflux in a boiling water bath in the solution for 1 hour to functionalize the surface. After the reaction is completed, wash with deionized water to neutrality after cooling. After drying, a black powder sample is obtained, which is a flower-shaped copper/copper oxide composite carrier; take 40mg The flower-like copper/copper oxide composite carrier and 100 mg of sodium citrate were ultrasonically dispersed in a water/methanol mixed solution with a volume ratio of 1:1, and then 5 mL of the noble metal precursor H ₂ PtCl ₆ and 5 mL of the noble metal precursor RuCl ₃ were added and adjusted The pH of the reaction system was 10, and then added KBH ₄ for reduction, washed with deionized water and dried in a vacuum oven at 40°C to finally obtain the black target product.

Comparative example 1

The noble metal Pt supported on multi-walled carbon nanotubes (MWCNTs) is used as an example for illustration. Take 40 mg of carrier MWCNTs and 100 mg of sodium citrate and ultrasonically disperse them in a water/ethanol solution with a volume ratio of 1:1, then add 10 mL of noble metal precursor H ₂ PtCl ₆ and adjust the pH of the reaction system to 10, then add KBH4 for reduction and use After washing with deionized water and drying in a vacuum oven at 40°C, the black target product was finally obtained.

Comparative example 2

Take XC-72 supporting noble metal Pt as an example to illustrate. Take 40mg carrier XC-72 and 100mg sodium citrate and ultrasonically disperse them in a water/ethanol solution with a volume ratio of 1:1, then add 10mL of noble metal precursor H ₂ PtCl ₆ and adjust the pH of the reaction system to 10, then add KBH ₄ After reduction, it was washed with deionized water and dried in a vacuum oven at 40° C. to finally obtain a black target product.

Example 6

Take the same amount (3 mg) of the flower-shaped copper/copper oxide supported platinum catalyst (Pt/F-Cu/CuO) prepared in Example 1, the Pt/MWCNTs catalyst prepared in Comparative Example 1 and the prepared Pt/MWCNTs catalyst in Comparative Example 2. Pt/XC-72 catalyst, dispersed in dispersant, then added proton exchange membrane (Nafion), the mixed solution was ultrasonically coated on the surface of the glassy carbon electrode, and a three-electrode system was formed, and the electrocatalysis of the catalyst was measured by an electrochemical workstation performance. The cyclic voltammetry curves of the catalyst to methanol, ethanol, ethylene glycol and glycerol are shown in Figure 3. Experiments show that the electrocatalytic alcohol oxidation performance of the flower-shaped copper/copper oxide supported platinum catalyst prepared in Example 1 It is better than the catalyst prepared by carbon nanotube support (MWCNTs) and carbon black support (XC-72) in the comparative example.

The flower-shaped copper/copper oxide composite micro-nano material carrier of the present invention supports mono- and binary noble metals as a catalyst, is suitable for catalytic oxidation of various small molecular acids and alcohols, and has good electrocatalytic activity and stability. According to the comparative examples, compared with the traditional carbon black and carbon nanotube supports, the inventive flower-shaped copper/copper oxide composite support supports noble metal catalysts with more excellent electrocatalytic activity and stability, and is a kind of catalyst with wide application Prospects for fuel cell catalysts.

The above embodiments have described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What are described in the above embodiments and description are only to illustrate the principles of the present invention. Without departing from the scope of the principle of the present invention, there will be various changes and improvements in the present invention, and these changes and improvements all fall within the protection scope of the present invention.

Claims (6)

1. A preparation method for a copper/copper oxide micro-nano composite loaded noble metal fuel cell catalyst, characterized in that the specific steps are: (1) Using copper chloride as copper source, glucose as carbon source, cetyltrimethylammonium bromide as surfactant and structure-directing agent, deionized water as solvent, hydrothermal reaction at 150-200℃ for 9 -48h, the product was washed with deionized water and absolute ethanol and then dried to obtain a black powder product; (2) Place the black powder product obtained in step (1) in a tube furnace and calcinate at 800°C for 3 hours, then take out the sample and disperse it in an alkali solution with a molar concentration of 0.5-3mol/L, heat it under reflux for 1-5 hours, and wait for the reaction Cool and wash with deionized water to neutrality after finishing, and obtain copper/copper oxide composite carrier after drying; (3) Ultrasonic disperse the copper/copper oxide composite carrier obtained in step (2) and sodium citrate in a hydroalcoholic solution, then add a noble metal precursor and adjust the pH of the reaction system to 10, then add a reducing agent for reduction and wash And drying to obtain the target product copper/copper oxide micro-nano composite material supported noble metal fuel cell catalyst, wherein the noble metal precursor is one or more of H ₂ PtCl ₆ , Na ₂ PdCl ₄ , RuCl ₃ or RhCl ₃ , and the reducing agent is _KBH4 , _NaBH4 , ascorbic acid or hydrazine hydrate. 2. the preparation method of copper/copper oxide micro-nano composite material loaded precious metal fuel cell catalyst according to claim 1, is characterized in that: the mass ratio of described cupric chloride and glucose is 1:10-10:1, The mass ratio of copper chloride to cetyltrimethylammonium bromide is 1:20-20:1. 3. The preparation method of copper/copper oxide micro/nano composite material supported noble metal fuel cell catalyst according to claim 1, characterized in that: the alkaline solution is potassium hydroxide solution, sodium hydroxide solution or ammonia solution. 4. The preparation method of copper/copper oxide micro-nano composite material loaded noble metal fuel cell catalyst according to claim 1, characterized in that: the morphology of the copper/copper oxide composite carrier is a multi-dimensional radial flower structure, Its size is 1-5 μm. 5. The preparation method of copper/copper oxide micro/nano composite material supporting noble metal fuel cell catalyst according to claim 1, characterized in that: the noble metal is Pt, Pd, PtPd, PtRu, PtRh, PdRu or PdRh. 6. The preparation method of the copper/copper oxide micro/nano composite material loaded noble metal fuel cell catalyst according to claim 1, characterized in that: the volume ratio of water and alcohol in the hydroalcoholic solution is 1:1, and the alcohol is specifically For methanol, ethanol or propanol.