CN101380594A - Titanium nitride carrier or mixed carrier of titanium nitride and carbon carrier for proton exchange membrane fuel cell catalyst - Google Patents

Abstract

Titanium nitride carrier or mixed carrier of titanium nitride and carbon carrier for proton exchange membrane fuel cell catalyst, characterized in that the carrier is composed of titanium nitride or mixed with titanium nitride and carbon carrier, wherein the carbon carrier is activated carbon, carbon nanotube One or more of carbon molecular sieves or carbon fibers; titanium nitride accounts for 1-100% of the total mass of the carrier. Specifically, it refers to the following method to obtain the carrier: (1), adding a noble metal compound to the suspension mixed with titanium nitride or titanium nitride and carbon carrier, the weight of the noble metal added accounts for 1-90% of the suspension; mix uniformly to obtain A; (2) Excessive reducing agent solution is added to A, and the reduced metal salt particles are adsorbed on the carrier to obtain B; (3), B is filtered, washed with water, and dried to obtain titanium nitride or titanium nitride and carbon composite carrier loading Catalyst; the particle size of noble metal is 1-20nm. The catalyst using the carrier of the present invention exhibits very high catalytic performance for the electrocatalytic reduction of methanol, formic acid, _H2 and CO mixed gas.

Description

Titanium nitride carrier or mixed carrier of titanium nitride and carbon carrier for proton exchange membrane fuel cell catalyst

technical field

The invention relates to a catalyst carrier, in particular to a titanium nitride carrier or a mixed carrier of titanium nitride and carbon carrier for a proton exchange membrane fuel cell catalyst. The noble metal catalyst supported by this support exhibits high catalytic performance for the electrochemical oxidation of methanol, formic acid, _H2 and CO mixed gas and the electrocatalytic reduction of oxygen.

Background technique

Due to the advantages of high energy conversion efficiency and low environmental pollution, fuel cells will become the best "clean energy" in the future, and many governments attach great importance to their research. In particular, direct alcohol fuel cells have attracted extensive attention in recent years due to their potential as power sources for electric vehicles and portable mobile power sources. Direct alcohol fuel cell anode catalysts are basically noble metal catalysts. However, because these metals are extremely expensive and resources are limited, batteries are expensive and difficult to commercialize. Therefore, it is hoped that the activity and utilization of metal catalysts can be improved as much as possible to reduce the cost of catalysts.

In proton exchange membrane fuel cells, generally speaking, there are several basic requirements for catalysts, namely high electrocatalytic activity, stability and electronic conductivity. At present, catalysts are generally noble metals or noble metal-based composite catalysts (such as Pt, Pd, Ir, Au, Ru, etc.), but because noble metals are expensive and resources are limited, effective measures must be taken to reduce the loading of noble metals. Therefore, in order to improve the catalytic efficiency of catalysts and reduce the amount of precious metals as much as possible, people choose substrates with high specific surface area, such as graphite, carbon black, activated carbon, molecular sieves, proton exchange membranes, etc., as noble metal supports. However, due to the different surface structures and surface groups of different supports, the interaction between the support and the active components is also different, resulting in changes in the catalytic activity of the catalyst. Therefore, finding supports that can enhance the performance of noble metal catalysts is a matter of concern.

To obtain highly active noble metal nanocatalysts, activated carbon is generally used as a carrier. However, since the surface of activated carbon contains more oxygen-containing groups, the presence of these oxygen-containing groups is beneficial to the anchoring of metal nanoparticles. But on the other hand, the interaction between noble metal particles and oxygen-containing groups also leads to changes in the electronic state of the metal surface, which leads to a decrease in catalyst activity.

Contents of the invention

Aiming at the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a titanium nitride carrier or a mixed carrier of titanium nitride and carbon carrier for a proton exchange membrane fuel cell catalyst. Compared with the traditional activated carbon, the catalyst prepared by using titanium nitride support or titanium nitride and carbon support as a mixed support shows excellent electrocatalytic performance; especially for methanol, formic acid, H ₂ and CO mixed gas. The chemical oxidation and electrocatalytic reduction of oxygen exhibit high catalytic performance.

The technical scheme of finishing above-mentioned invention task is:

A titanium nitride carrier or a mixed carrier of titanium nitride and carbon carrier for a proton exchange membrane fuel cell catalyst, characterized in that:

The carrier is composed of titanium nitride or a mixture of titanium nitride and carbon carrier, wherein the carbon carrier is one or more of activated carbon, carbon nanotubes, carbon molecular sieves or carbon fibers, and the titanium nitride accounts for 1-100% of the total mass of the carrier.

In other words, the titanium nitride carrier or the titanium nitride and carbon carrier mixed carrier of the proton exchange membrane fuel cell catalyst of the present invention is that the catalyst carrier is a titanium nitride carrier or a titanium nitride and carbon carrier mixed carrier; The proton exchange membrane fuel cell catalyst is a noble metal or a noble metal-based catalyst; the noble metal is one or more of Pt, Pd, Au, Ir or Ru.

The added mass of the noble metal described in the above scheme generally accounts for 1-90% of the total mass of the catalyst.

In more detail, the titanium nitride carrier or the titanium nitride and carbon carrier mixed carrier of the proton exchange membrane fuel cell catalyst of the present invention refers to the titanium nitride carrier or the nitrogen carrier of the proton exchange membrane fuel cell catalyst prepared by the following method Titanium oxide and carbon carrier mixed carrier:

(1) Add noble metal compounds: H ₂ PtCl ₆ , K ₂ PtCl ₆ , PdCl ₂ , Pd(NO ₃ ) ₂ , HAuCl to the suspension of titanium nitride or the suspension mixed with titanium nitride and carbon support _4. One or more of IrCl ₃ or RuCl ₃ , in which the mass of noble metal generally accounts for 1-90% of the total mass of the suspension; ultrasonically mixes evenly to obtain Component A.

(2) Slowly add excess reducing agent solution to component A to reduce the metal salt and adsorb the reduced metal salt particles on the carrier to obtain component B.

(3) Component B is filtered, washed with water, and dried to obtain a catalyst supported by a titanium nitride or titanium nitride and carbon composite carrier; the particle size of the noble metal is 1-20 nm.

More specifically and more optimally, the preparation method of the titanium nitride carrier of the proton exchange membrane fuel cell catalyst or the mixed carrier of titanium nitride and carbon carrier, the specific steps are as follows,

(1) Injection of catalyst precursor: Weigh a certain amount of titanium nitride and carbon support (titanium nitride accounts for 1-100% of the total mass of the support) and disperse them in water, vibrate ultrasonically to form a suspension. Add a certain proportion of noble metal compounds (one or more of H ₂ PtCl ₆ , K ₂ PtCl ₆ , PdCl ₂ , Pd(NO ₃ ) ₂ , HAuCl ₄ , IrCl ₃ , RuCl ₃ ) to the suspension, noble metal The mass added generally accounts for 1-90% of the total mass of the catalyst. Continue to sonicate to make the mixture uniform, and obtain component A.

(2) Liquid phase reduction: Slowly add excess reducing agent solution (such as NaBH ₄ , polyoxymethylene, Na ₂ S ₂ O ₄ , sodium formate, Na ₂ SO ₃ , etc. ) fully react the metal salt and the reducing agent by mechanical stirring or ultrasonic vibration, so that the reduced metal salt particles are adsorbed on the carrier to obtain component B.

(3) Post-treatment part: After filtering the component B, wash it with water successively until there is no chloride ion in the eluate, and then dry it to prepare the catalyst supported by titanium nitride or titanium nitride and carbon composite carrier. The carbon carrier is one or more of activated carbon, carbon nanotubes, carbon molecular sieves, carbon fibers and the like. The percentage of the titanium nitride in the total mass of the carbon support and the titanium nitride is 1-100%; the particle size of the noble metal is 1-20nm.

The catalyst loaded on the titanium nitride carrier or the mixed carrier of titanium nitride and carbon carrier is noble metal: one or more of Pt, Pd, Au, Ir or Ru.

The invention has the advantages that the noble metal and the noble metal-based catalyst of the proton exchange membrane fuel cell are prepared by using titanium nitride as a carrier or titanium nitride and carbon carrier as a mixed carrier. The feature of the present invention is that titanium nitride is used in the carrier of noble metal and noble metal-based catalyst.

Electrochemical research methods such as cyclic voltammetry show that compared with traditional activated carbon, catalysts prepared using titanium nitride support or titanium nitride and carbon support as a mixed support show excellent electrocatalytic performance; especially for methanol The electrochemical oxidation of , formic acid, H ₂ and CO mixed gas and the electrocatalytic reduction of oxygen exhibited high catalytic performance.

Description of drawings

Figure 1 is the XRD pattern of the Pd/TiN-C catalyst with a metal loading of 20% and a TiN:C mass ratio of 1:2. Among them, the XRD patterns of Pd/TiN-C (1:2) (curve a), E-TEKPd/C sample (curve b) and TiN prepared by complex reduction; The average particle size of the metal particles is about 4nm, which is similar to the sample of ETEK company.

Figure 2 is a TEM photograph of a Pd/TiN-C catalyst with 20% TiN:C mass ratio of 1:2. The photos clearly show that the Pd composite carrier catalyst prepared by the liquid phase reduction method has an average particle diameter of about 4nm metal particles, and the metal particles have good uniformity and dispersion.

Figure 3 shows the 20% Pd/TiN-C catalyst with a mass ratio of TiN:C of 1:2 and the commercialized E-TEK company's similar Pd/C catalyst in 0.5mol/L H ₂ SO ₄ +0.5mol/L HCOOH solution The cyclic voltammogram in . The linear sweep voltammograms of Pd/TiN-C (curve a) and ETEK sample (curve b) prepared by complex reduction in 0.5mol/L H ₂ SO ₄ +0.5mol/L HCOOH solution. Scan rate: 50mV/s, temperature: 30°C.

The oxidation peaks of formic acid in the positive sweep direction of the cyclic voltammetry curves all appeared at about 0.20V, but the peak current densities were different. The peak current densities of formic acid oxidation on homemade Pd/TiN-C(1:2) catalyst and commercial E-TEK catalyst were 26.69 and 16.22mA/cm ² , respectively. Compared with the samples from E-TEK Company, the electrocatalytic oxidation performance of the self-made Pd/TiN-C catalyst for formic acid was nearly doubled.

Detailed ways

Example 1:

Weigh 60 mg of titanium nitride, add 112.68 mL of 0.04504 mol/L PdCl ₂ solution, stir to mix evenly.

(2) At 100°C, slowly add excess reducing agent solution (polyoxymethylene) and stir to completely react the metal salt and reducing agent.

(3), filter and wash until there is no chloride ion in the eluate. After drying, the Pd/TiN catalyst is obtained.

The titanium nitride accounts for 100% of the total mass of the carrier, the noble metal load is 90% of the total mass of the catalyst, and the reduction temperature is 100°C.

Example 2:

Weigh 1 mg of titanium nitride and 99 mg of activated carbon. Add 0.115 mL of 0.04504 mol/L H ₂ PtCl ₆ solution, and stir to make the mixture uniform.

(2) At 0°C, slowly add excess reducing agent solution (NaBH ₄ ), and stir to completely react the metal salt and reducing agent.

(3), filter and wash until there is no chloride ion in the eluate. After drying, a Pt/TiN-C catalyst is obtained, wherein the loading of Pt metal is 1%.

The titanium nitride accounts for 1% of the total mass of the carrier, the loading of the noble metal is 1% of the total mass of the catalyst, and the reduction temperature is 0°C.

Example 3:

Weigh 20 mg of carbon nanotubes and 40 mg of titanium nitride. Add 1.32ml of 0.0386mol/L H ₂ PtCl ₆ solution and 1.06ml of 0.04504mol/L PdCl ₂ , stir to make the mixture uniform.

(2) At 25°C, slowly add excess reducing agent solution (NaBH ₄ ), and stir to completely react the metal salt and reducing agent.

(3), filter and wash until there is no chloride ion in the eluate. After drying, a PtPd/TiN-CNTs catalyst is obtained, wherein the loading of Pt metal is 13%, and the loading of Pd metal is 7%.

Example 4:

Weigh 20 mg of carbon molecular sieve and 40 mg of titanium nitride. Add 1.32mL of 0.0386mol/L H ₂ PtCl ₆ solution and 1.1mL of 0.04504mol/L RuCl ₃ , stir to make the mixture uniform.

(2) At 25°C, slowly add excess reducing agent solution (Na ₂ S ₂ O ₄ ), and stir to completely react the metal salt and reducing agent.

(3), filter and wash until there is no chloride ion in the eluate. After drying, a PtRu/TiN-C catalyst is prepared, wherein the loading of Pt metal is 13%, and the loading of Ru metal is 7%.

Example 5

Weigh 20 mg of carbon fiber and 40 mg of titanium nitride, add 2.07 ml of 0.04504 mol/L PdCl ₂ solution and 0.52 mL of 0.09635 mol/L RuCl ₃ , and stir to make the mixture uniform.

(2) At 10°C, slowly add excess reducing agent solution (sodium formate), and stir to completely react the metal salt and reducing agent.

(3), filter and wash until there is no chloride ion in the eluate. After drying, a PdRu/TiN-carbon fiber catalyst is obtained, wherein the loading of Pd metal is 13%, and the loading of Ru metal is 7%.

Example 6

Weigh 20 mg of activated carbon and 40 mg of titanium nitride. Add 1.32mL of 0.0386mol/L H ₂ PtCl ₆ solution and 0.57mL of 0.04504mol/L HAuCl ₄ , stir to make the mixture uniform.

(2) At 25°C, slowly add excess reducing agent solution (Na ₂ SO ₃ ), and stir to completely react the metal salt and reducing agent.

(3), filter and wash until there is no chloride ion in the eluate. After drying, a PtAu/TiN-C catalyst is prepared, wherein the loading of Pt metal is 13%, and the loading of Au metal is 7%.

Example 7,

It is basically the same as Example 3, but there are the following differences: Pd(NO ₃ ) ₂ is used as the precursor of Pd.

Embodiment 8 is basically the same as Embodiment 6, but has the following difference: the added second metal is Ir. The atomic ratio of Pt and Ir is 1:1.

Example 8,

It is basically the same as Example 3, but there are the following differences: the noble metal compound is: K ₂ PtCl ₆ .

Example 9,

It is basically the same as Example 3, but there are the following differences: the noble metal compound is: IrCl ₃ or RuCl ₃ .

Claims (6)

1, a kind of titanium nitride carrier of proton exchange membrane fuel cell catalyst or titanium nitride and carbon carrier mixed carrier, it is characterized in that: The carrier is composed of titanium nitride or a mixture of titanium nitride and carbon carrier, wherein the carbon carrier is one or more of activated carbon, carbon nanotubes, carbon molecular sieves or carbon fibers; the titanium nitride Accounting for 1-100% of the total mass of the carrier. 2, the titanium nitride carrier of proton exchange membrane fuel cell catalyst according to claim 1 or titanium nitride and carbon carrier mixed carrier, it is characterized in that: the catalyst of described proton exchange membrane fuel cell is noble metal and noble metal-based catalyst ; The noble metal is one or more of Pt, Pd, Au, Ir or Ru. 3. The titanium nitride carrier or titanium nitride and carbon carrier mixed carrier of the proton exchange membrane fuel cell catalyst according to claim 2, characterized in that: the added quality of the noble metal accounts for 1 to 90% of the total mass of the catalyst . 4, according to claim 1 or 2 or 3 described proton exchange membrane fuel cell catalyst titanium nitride carrier or titanium nitride and carbon carrier mixed carrier, it is characterized in that: the nitriding of described proton exchange membrane fuel cell catalyst Titanium carrier or titanium nitride and carbon carrier mixed carrier refer to the titanium nitride carrier or titanium nitride and carbon carrier mixed carrier of the proton exchange membrane fuel cell catalyst prepared by following method: (1) Add noble metal compounds: H ₂ PtCl ₆ , K ₂ PtCl ₆ , PdCl ₂ , Pd(NO ₃ ) ₂ , HAuCl to the suspension of titanium nitride or the suspension mixed with titanium nitride and carbon support _4. One or more of IrCl ₃ or RuCl ₃ , in which the mass of noble metal generally accounts for 1-90% of the total mass of the suspension; ultrasonically mixes evenly to obtain Component A. (2) Slowly add excess reducing agent solution to component A to reduce the metal salt and adsorb the reduced metal salt particles on the carrier to obtain component B. (3) Component B is filtered, washed with water, and dried to obtain a catalyst supported by a titanium nitride or titanium nitride and carbon composite carrier; the particle size of the noble metal is 1-20 nm. 5, the titanium nitride carrier of proton exchange membrane fuel cell catalyst according to claim 4 or titanium nitride and carbon carrier mixed carrier, it is characterized in that: the titanium nitride carrier of described proton exchange membrane fuel cell catalyst or nitrogen The preparation method of titanium oxide and carbon carrier mixed carrier, concrete steps are as follows, (1) Injection of catalyst precursor: Weigh titanium nitride or titanium nitride and carbon carrier, disperse in water, and ultrasonically vibrate to form a suspension. A certain proportion of noble metal compound is added to the suspension, and the added mass of the noble metal generally accounts for 1-90% of the total mass of the catalyst. Continue to sonicate to make the mixture uniform, and obtain component A; (2) Liquid-phase reduction: Slowly add the excess reducing agent solution to the obtained component A at 0-100°C, and through mechanical stirring or ultrasonic vibration, the metal salt and the reducing agent are fully reacted, so that the reduced The metal salt particles are adsorbed on the carrier to obtain component B; (3), after-treatment part: after component B is filtered, wash with water successively until there is no chloride ion in the eluate, and then dry to obtain the catalyst supported by titanium nitride or titanium nitride and carbon composite carrier. The carbon carrier is one or more of activated carbon, carbon nanotubes, carbon molecular sieves, carbon fibers and the like. The percentage of the titanium nitride in the total mass of the carbon support and the titanium nitride is 1-100%; the particle size of the noble metal is 1-20nm. 6. The titanium nitride carrier or titanium nitride and carbon carrier mixed carrier of the proton exchange membrane fuel cell catalyst according to claim 4 or 5, is characterized in that: described precious metal compound is selected from: H ₂ PtCl ₆ , K ₂ One or more of PtCl ₆ , PdCl ₂ , Pd(NO ₃ ) ₂ , HAuCl ₄ , IrCl ₃ , RuCl ₃ ; the excess reducing agent solution is NaBH ₄ , polyformaldehyde, Na ₂ S ₂ O ₄ , sodium formate or Na ₂ SO ₃ solution.

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