CN103259023B - A kind of hydrogen cell electrode material preparation method - Google Patents

Abstract

The invention relates to a method for preparing fuel cell electrode materials, in particular to a method for growing carbon nanotubes (CNT) and carrying platinum (Pt) on the surface of carbon paper. The method comprises the following process steps: (1) depositing a catalyst for growing carbon nanotubes on carbon paper by means of ion sputtering; (2) growing carbon nanotubes on the surface of carbon paper by plasma enhanced chemical vapor deposition; (3) depositing The carbon paper with carbon nanotubes was deposited platinum catalyst on the carbon nanotubes by ion sputtering.

Description

A kind of preparation method of hydrogen fuel cell electrode material

technical field

The invention relates to a method for preparing an electrode material for a fuel cell, in particular to a platinum-loaded carbon nanotube grown in situ on the surface of a carbon fiber paper used for a proton exchange membrane fuel cell and a preparation method thereof.

Background technique

A fuel cell is a device that directly converts chemical energy into low-voltage direct current through the electrochemical reaction of fuel and oxidant. Fuel cell is recognized as the preferred clean and efficient power generation technology in the 21st century. Its research and development has become a research hotspot in the field of international energy, and will promote the rapid development of the entire electric vehicle, submarine and power generation industry.

So far, various types of fuel cells have been researched and developed, among which proton exchange membrane fuel cells (PEMFC) are secondary to alkaline fuel cells, phosphoric acid fuel cells, molten carbonate fuel cells and solid oxide fuel cells. After the fifth generation of fuel cells. Due to the use of solid electrolyte polymer membrane as electrolyte, it has the outstanding advantages of high energy conversion rate, low temperature start-up, no leakage of electrolytic cell, no corrosion, long life and high specific power. The research on PEMFC has become the mainstream of various fuel cell research tides, and it is the fuel cell that is expected to be commercialized the fastest.

Carbon nanotubes have a unique one-dimensional tubular graphitized structure, large specific surface area, low electrical resistance, and high chemical stability, making them ideal carriers for nanocatalysts. Noble metal nanoparticles with unique catalytic properties are supported on the surface of carbon nanotubes, and the noble metal nanoparticles/carbon nanotube composites formed not only have the excellent properties of the two nanomaterials, but may also produce new properties. Using carbon nanotubes as the catalyst carrier can increase the catalyst load, and the dispersion of platinum on the carrier and the active center are also significantly improved. Carbon nanotubes have high mechanical strength and can form an interpenetrating network structure in the catalytic layer, which improves the strength of the catalytic layer and is conducive to improving the durability of membrane electrode fuel cells. Compared with traditional carbon materials, the electrons in carbon nanotubes The kinetic behavior of the transfer is the best. Therefore, carbon nanotubes have a good application prospect in fuel cell catalyst supports.

The patent "Carbon Nanotube Electrode and Manufacturing Method for Growing Carbon Nanotubes Directly on the Surface of Carbon Paper and Carrying Platinum Nanocatalyst on the Surface of Carbon Nanotubes by CVD Method", Patent No. 200710198794.7, also proposes to grow carbon nanotubes on the surface of carbon paper Tubes and loaded with platinum as fuel cell electrode materials, the preparation method is (1) soaking carbon paper in sulfuric acid aqueous solution for pretreatment and drying; (2) soaking the treated carbon paper in nickel, cobalt, iron compounds or their mixtures In the aqueous solution of electric spheres, ultrasonic treatment is repeated to make the above metals evenly distributed on the surface of carbon paper; (3) gaseous carbon source is introduced on the surface of carbon paper loaded with catalyst metal, and the appropriate temperature and pressure are maintained to grow carbon nanotubes. (4) remove nickel, cobalt, iron or its mixture metals from the grown carbon nanotubes, and carry out surface treatment to the carbon nanotubes; (5) pass into the gas-phase platinum electric sphere on the carbon paper that has grown the carbon nanotubes , maintain a certain temperature and pressure, and load the platinum nano-catalyst.

The method of this patent is (1) using ion sputtering method to sputter a layer of catalyst of nickel, iron or their mixture on the surface of carbon fiber paper, and argon protection is introduced during the sputtering process; (2) _H2 is introduced on the surface of carbon paper , maintain the appropriate temperature and pressure, so that the catalyst is fully reduced; (3) pass the gaseous carbon source on the surface of the carbon paper after the reduction treatment, maintain the appropriate temperature and pressure, and grow carbon nanometers under a certain radio frequency power and bias voltage (4) Soak and dry the carbon paper with carbon nanotubes grown in hydrochloric acid solution to remove metals such as iron and nickel; (5) perform platinum target ionization on the carbon paper grown with carbon nanotubes under an argon atmosphere. Sputtering, supported platinum catalyst. The operation method of this patent is simple, and the carbon paper does not need pretreatment. Due to the use of plasma enhancement and bias in the growth process of carbon nanotubes, the growth density of carbon nanotubes is high, the diameter of the tubes is uniform, and the ion sputtering platinum particles are small. The uniform distribution on the surface of the nanotubes can lead to better catalytic performance.

The patent "low-platinum highly active core-shell structure catalyst and its preparation method", patent number 200910117488.5 covers platinum on the metal-based core to form a core-shell structure, and supports it on carbon powder or carbon nanotube carrier. Patent "Preparation Method of Platinum Electrode Catalyst Supported on Carbon Nanotubes", Patent No. 02155255.X uses carbon nanotubes as a carrier, and prepares Pt/CNTs catalysts by reducing and depositing chloroplatinic acid on carbon nanotubes. Patent "Preparation Method of Carbon Nanotube-supported Platinum Ruthenium Anti-CO Electrode Catalyst", patent No. 02155256.8 Using carbon nanotubes as the carrier, using in-situ chemical homogeneous deposition method, the metastable colloidal reduction deposition of Pt, Ru, Sn plasma on carbon nanotubes. Patent "A Preparation Method of Surface Nitrile-Modified Multi-walled Carbon Nanotubes Supported Nano-Platinum Catalyst", Patent No. 201010168318.2 Using surface nitrile-modified multi-walled carbon nanotubes as a carrier, alcohol as a reducing agent, and chlorine Platinic acid is reductively deposited onto carbon nanotubes. Patent "A Platinum/Carbon Nanotube Catalyst and Its Preparation and Application", Patent No. 200910236390.1 Immerse carbon nanotubes in an aqueous solution of chloroplatinic acid, stir and impregnate them, grind them after drying, and heat and reduce them with aqueous sodium formate to obtain platinum/carbon nanotubes catalyst. Patent "A Highly Stable Fuel Cell Cathode Catalyst Suitable for Dynamic Working Conditions", Patent No. 200910248845.1 The commercially available carbon nanotubes are pretreated, and then loaded with active components to obtain carbon nanotube-supported platinum catalysts. The patent "A Preparation Method of Carbon Nanotube-supported Cobalt-Platinum Alloy Catalyst", patent number 200810224481.9 contains cobalt. The carbon nanotube working electrode of the platinum-based active material precursor is used as the cathode, the platinum electrode is used as the anode, and the solid-phase electrolytic salt is used as the electrolyte. Pulse electrodeposition is used to generate carbon nanotube-supported cobalt-platinum alloy catalysts. Patent "A Preparation Method of Proton Exchange Membrane Fuel Cell Cathode Catalyst", Patent No. 200910085170.3 Disperse carbon nanotubes into two book solutions, and use formic acid reduction method to support Pt to generate catalyst. Patent "Carbon Nanotube-supported Platinum Catalyst for Fuel Cell and Its Preparation Method", Patent No. 200410009870.1 The carbon nanotubes are pretreated first, and then the Pt/MWNTs catalyst is prepared by the formaldehyde reduction method. The method of this patent is to directly grow carbon nanotubes in situ on the surface of carbon paper, and prepare platinum nanoparticles on the surface of carbon nanotubes by ion sputtering. The preparation method is different from the above patent.

Contents of the invention

The purpose of the invention is to provide a platinum/carbon nanotube/carbon fiber paper electrode material for proton exchange membrane fuel cells with good catalyst dispersion and high catalytic activity.

Another object of the present invention is to provide a method for mass-producing platinum/carbon nanotube/carbon fiber paper electrode materials for proton exchange membrane fuel cells and assembling them into single cells.

The platinum/carbon nanotube/carbon fiber paper electrode material for fuel cells of the present invention uses carbon fiber paper as a carrier to grow carbon nanotubes in situ, and uses the carbon nanotubes as a carrier to sputter platinum catalysts. Wherein, the diameter of the carbon nanotube is 20-40nm, the diameter of the platinum particle is 2-4nm, and the platinum particle is uniformly dispersed on the surface of the carbon nanotube.

The preparation method of the platinum/carbon nanotube/carbon fiber paper electrode material used for fuel cells of the present invention is to sputter nickel and iron catalysts on the surface of carbon fiber paper, and then adopt plasma enhanced chemical vapor deposition (PECVD) to grow carbon in situ nanotubes, and finally sputtering a platinum catalyst on the surface of the carbon nanotubes, the method includes the following steps:

(1) Sputtering nickel and iron catalysts: use ion sputtering method to sputter a layer of nickel or iron catalyst film on the surface of carbon fiber paper, and pass into argon protection during the sputtering process;

(2) Catalyst reduction: the carbon fiber paper obtained after the treatment in step (1) is reduced under _H2 atmosphere at 200-1000° C. for 0.5-5.0 hours;

(3) Growth of carbon nanotubes: process the product obtained in step (2) under H ₂ and CH ₄ atmosphere at 600-1000° C. for 0.5-5 hours to obtain carbon nanotubes grown in situ on the surface of carbon fiber paper, and cool to Take it out after it is below 100°C;

(4) Soak and dry the product obtained in step (3) in hydrochloric acid solution to remove metals such as iron and nickel;

(5) The product obtained in step (4) is subjected to ion sputtering of platinum nanoparticles under an argon atmosphere.

The carbon nanotubes grown on the surface of carbon paper by the method of the present invention have high density, uniform distribution, firm combination with carbon fiber paper, tube diameter of 20-40nm, good dispersion of platinum particles, and platinum particle diameter of 2-4nm , showing good catalytic performance.

Using this method to prepare fuel cell electrode materials avoids the dispersion step of carbon nanotubes, the operation process is simple, and the bonding strength between carbon nanotubes and carbon fiber paper matrix is increased, and the dispersion of platinum catalyst on the surface of carbon nanotubes is improved. , improve the utilization rate of platinum catalysts, and realize the mass production of proton exchange membrane fuel cell electrode materials.

The morphology characteristics of the platinum/carbon nanotube/carbon fiber paper electrode material for the proton exchange membrane fuel cell prepared by the method of the invention are characterized by a scanning electron microscope (SEM).

Description of drawings

Figure 1 is a scanning electron micrograph of platinum/carbon nanotube/carbon fiber paper.

detailed description

Example 1:

(1) Sputtering nickel catalyst: use ion sputtering method to sputter a layer of nickel catalyst film on the surface of carbon fiber paper. During the sputtering process, argon protection is introduced. The pressure of argon is 0.1-1MPa, and the sputtering pressure is 2- 10×10 ^-1 Pa, the sputtering current is 1-10mA, and the sputtering time is 5-60min;

(2) Catalyst reduction: the carbon fiber paper obtained after the treatment in step ( ₁ ) was reduced in H atmosphere for 0.5 to ₅ hours, the H pressure was 100 to 1000 Pa, and the H flow was ₁₀ to 100 sccm;

(3) Treat the product obtained in step (2) in H ₂ and CH ₄ atmosphere for 0.5 to 5 hours to obtain carbon nanotubes grown in situ on the surface of carbon fiber paper, take it out after cooling down to below 100°C, and the pressure of the gas is 100～1000Pa, H ₂ flow rate is 10～100sccm, CH ₄ flow rate is 10～100sccm, RF power is 0～200W, negative bias voltage is 0V;

(4) Soak and dry the product obtained in step (3) in 2mol/L hydrochloric acid solution to remove metals such as iron and nickel;

(5) The product obtained in step (4) is subjected to ion ^sputtering of platinum particles under an argon atmosphere. 1 ~ 10mA, sputtering time is 10 ~ 60s.

Example 2:

(1) Sputtering nickel catalyst: use ion sputtering method to sputter a layer of nickel catalyst film on the surface of carbon fiber paper. During the sputtering process, argon protection is introduced. The pressure of argon is 0.1-1MPa, and the sputtering pressure is 2- 10×10 ^-1 Pa, the sputtering current is 1-10mA, and the sputtering time is 5-60min;

(2) Catalyst reduction: the carbon fiber paper obtained after the treatment in step ( ₁ ) was reduced in H atmosphere for 0.5 to ₅ hours, the H pressure was 100 to 1000 Pa, and the H flow was ₁₀ to 100 sccm;

(3) Treat the product obtained in step (2) in H ₂ and CH ₄ atmosphere for 0.5 to 5 hours to obtain carbon nanotubes grown in situ on the surface of carbon fiber paper, take it out after cooling down to below 100°C, and the pressure of the gas is 100～1000Pa, H ₂ flow rate is 10～100sccm, CH ₄ flow rate is 10～100sccm, RF power is 0～200W, negative bias voltage is 25V;

(4) Soak and dry the product obtained in step (3) in 2mol/L hydrochloric acid solution to remove metals such as iron and nickel;

(5) The product obtained in step (4) is subjected to ion ^sputtering of platinum particles under an argon atmosphere. 1 ~ 10mA, sputtering time is 10 ~ 60s.

Example 3:

(1) Sputtering iron catalyst: use ion sputtering method to sputter a layer of iron catalyst film on the surface of carbon fiber paper. During the sputtering process, argon gas protection is introduced. The pressure of argon gas is 0.1-1MPa, and the sputtering pressure is 2-2 10×10 ^-1 Pa, the sputtering current is 1-10mA, and the sputtering time is 5-60min;

(2) Catalyst reduction: the carbon fiber paper obtained after the treatment in step ( ₁ ) was reduced in H atmosphere for 0.5 to ₅ hours, the H pressure was 100 to 1000 Pa, and the H flow was ₁₀ to 100 sccm;

(3) Treat the product obtained in step (2) in H ₂ and CH ₄ atmosphere for 0.5 to 5 hours to obtain carbon nanotubes grown in situ on the surface of carbon fiber paper, take it out after cooling down to below 100°C, and the pressure of the gas is 100～1000Pa, H ₂ flow rate is 10～100sccm, CH ₄ flow rate is 10～100sccm, RF power is 0～200W, negative bias voltage is 50V;

(4) Soak and dry the product obtained in step (3) in 2mol/L hydrochloric acid solution to remove metals such as iron and nickel;

(5) The product obtained in step (4) is subjected to ion ^sputtering of platinum particles under an argon atmosphere. 1 ~ 10mA, sputtering time is 10 ~ 60s.

Example 4:

(1) Sputtering iron catalyst: use ion sputtering method to sputter a layer of iron catalyst film on the surface of carbon fiber paper. During the sputtering process, argon gas protection is introduced. The pressure of argon gas is 0.1-1MPa, and the sputtering pressure is 2-2 10×10 ^-1 Pa, the sputtering current is 1-10mA, and the sputtering time is 5-60min;

(2) Catalyst reduction: the carbon fiber paper obtained after the treatment in step ( ₁ ) was reduced in H atmosphere for 0.5 to ₅ hours, the H pressure was 100 to 1000 Pa, and the H flow was ₁₀ to 100 sccm;

(3) Treat the product obtained in step (2) in H ₂ and CH ₄ atmosphere for 0.5 to 5 hours to obtain carbon nanotubes grown in situ on the surface of carbon fiber paper, take it out after cooling down to below 100°C, and the pressure of the gas is 100～1000Pa, H ₂ flow rate is 10～100sccm, CH ₄ flow rate is 10～100sccm, RF power is 0～200W, negative bias voltage is 75V;

(4) Soak and dry the product obtained in step (3) in 2mol/L hydrochloric acid solution to remove metals such as iron and nickel;

(5) The product obtained in step (4) is subjected to ion ^sputtering of platinum particles under an argon atmosphere. 1 ~ 10mA, sputtering time is 10 ~ 60s.

Claims (7)

1. A method for preparing a platinum/carbon nanotube/carbon fiber paper electrode material for fuel cells, using carbon fiber paper as a carrier, growing carbon nanotubes in situ, and using carbon nanotubes as a carrier, using platinum as a catalyst, platinum The particles are evenly dispersed on the surface of the carbon nanotubes, and the method is characterized in that the method comprises the following steps: (1) Sputter a catalyst film of nickel or iron on the surface of carbon fiber paper by ion sputtering, and pass into argon protection during the sputtering process; (2) The carbon fiber paper obtained after the treatment of step (1) was reduced under H ₂ atmosphere at 200° C. for 5.0 hours; (3) Treat the product obtained in step (2) under _H2 and _CH4 atmosphere at 600-1000°C for 0.5-5 hours, and use plasma-enhanced chemical vapor deposition method PECVD to prepare carbon nanometers grown in situ on the surface of carbon fiber paper. Take out the tube after cooling down to below 100°C; the pressure of the gas is 100-1000Pa, the flow rate of _H2 is 10-100sccm, the flow rate of _CH4 is 10-100sccm, the radio frequency power is 0-200W, and the negative bias voltage is 0-100V; (4) Soak and dry the product obtained in step (3) in hydrochloric acid solution to remove iron and nickel metal; (5) The product obtained in step (4) is subjected to ion sputtering of platinum particles under an argon atmosphere. 2. the preparation method of the platinum/carbon nanotube/carbon fiber paper electrode material that is used for fuel cell according to claim 1, is characterized in that: the diameter of described carbon nanotube is 20～40nm, and the diameter of platinum particle is 2. ~4nm. 3. The method according to claim 1, characterized in that in the step (1), the sputtering pressure is 2×10 ^-1 ~ 10×10 ^-1 Pa, the sputtering current is 1 ~ 10mA, and the sputtering The time is 5-60 minutes. 4. The method according to claim 1, characterized in that, in the step (2), the _H2 pressure is 100-1000 Pa, and the _H2 flow rate is 10-100 sccm. 5. The method according to claim 1, characterized in that, in the step (4), the concentration of hydrochloric acid is 2mol/L, the soaking time is 12-24 hours, the drying temperature is 100-120°C, and the drying time is 1-2 hours. Hour. 6. The method according to claim 1, characterized in that, in the step (5), the sputtering pressure is 2×10 ^-1 ~ 10×10 ^-1 Pa, the sputtering current is 1 ~ 10mA, and the sputtering The time is 10-60s. 7. The method according to claim 1, characterized in that the pressure of argon is 0.1-1 MPa.