CN104998636A - Synthetic method and application of PtRu binary metal nano-alloy catalyst - Google Patents

Abstract

The invention discloses a PtRu binary metal nano-alloy catalyst with a flower-like (porous) structure, which is characterized in that: (1) adding a surfactant and a reducing agent into water, stirring at room temperature for 10-30 minutes, the surface activity The mass ratio of the surfactant to the reducing agent is 1:2 to 2:1; the amount of water added needs to completely dissolve the surfactant and the reducing agent; (2) Add metal platinum salts to the mixed solution obtained in step (1) Precursor solution and metal ruthenium salt precursor solution, the volume ratio of the two is: 3:2～2:3, the ratio of the mixed solution to the total volume of the metal precursor solution is 10:1～20:1; stirring at room temperature for 10～30 Minutes, the concentration of the metal salt precursor solution is 0.05-0.5mol/L; (3) Stir the mixed solution obtained in step (2) at room temperature for 5-30 minutes, react in an autoclave for 1.5-3 hours, and control the temperature at 180 ~230°C; (4) Cool the product obtained in step (3), wash it, and centrifuge to obtain a PtRu binary metal nano-alloy catalyst with a flower-like (pore-like) structure.

Description

A kind of synthetic method and application of PtRu binary metal nano-alloy catalyst

technical field

The invention relates to the field of fuel cell catalysts, in particular to the synthesis and application of a PtRu binary metal nano-alloy catalyst.

Background technique

Due to its high energy conversion rate and low environmental pollution, fuel cells are conducive to reducing the excessive use of traditional fossil fuels and protecting the global environment. A lot of manpower, material resources, and financial resources have been invested in research. Methanol is a liquid organic compound with the simplest structure at normal temperature and pressure. It is easy to store, convenient to source, and cheap. It is an ideal renewable fuel. Pt catalysts have attracted extensive attention due to their excellent catalytic activity and stability towards methanol. However, due to its scarcity and high price on the earth, the commercial use of fuel cells is greatly limited, and CO, an intermediate oxidation product of methanol, will occupy the active sites on the Pt surface, poisoning the Pt catalyst, thereby reducing the Pt electrochemical activity and stability. The key to enhancing catalyst activity is the oxidation of CO-like intermediates at low potentials. At present, the alloying of Pt is a common method adopted by scientists to solve the problem of low catalytic activity and easy poisoning of single metal Pt. Pt-based binary nanoalloys have attracted increasing attention due to their unique physicochemical properties. Among them, PtRu binary nanoalloys have attracted extensive attention due to their better electrochemical activity and CO toxicity resistance. However, few of the reported PtRu binary metal nanoalloy catalysts have both high activity and high stability. The flower-like (pore-like) structure of the binary metal nano-alloy catalyst not only has both catalytic activity and stability, but also has a greater degree of improvement in both aspects than the previously reported PtRu binary nano-catalysts.

Contents of the invention

The technical problem to be solved by the present invention is to provide a PtRu binary metal nano-alloy catalyst with a flower-like (pore-like) structure, which enhances the catalyst's ability to resist CO poisoning and improves the catalytic activity to methanol, formaldehyde and formic acid.

The technical scheme of the present invention is: a kind of preparation method of the PtRu binary metal nano-alloy catalyst of flower-like (porous) structure, comprises the following steps:

(1) Add surfactant and reducing agent into water together, stir at room temperature for 10 to 30 minutes, the mass ratio of surfactant to reducing agent is 1:2 to 2:1; the amount of water added needs to be equal to surfactant and The reducing agent is completely dissolved;

(2) Add metal platinum salt precursor solution and metal ruthenium salt precursor solution respectively to the mixed solution obtained in step (1), the volume ratio of the two is: 3:2～2:3, the mixed solution and the metal precursor solution The ratio of the total volume is 10:1-20:1; stirring at room temperature for 10-30 minutes, the concentration of the metal salt precursor solution is 0.05-0.5mol/L;

(3) Stir the mixed solution obtained in step (2) at room temperature for 5-30 minutes, react in an autoclave for 1.5-3 hours, and control the temperature at 180-230°C;

(4) The product obtained in step (3) is cooled, washed, and centrifuged to obtain a PtRu binary metal nano-alloy catalyst with a flower-like (pore-like) structure.

The aqueous solution in step (1) is ultrapure water, the stirring time is 20 minutes, and the mass ratio of surfactant to reducing agent is 2:3.

The surfactant in step (1) is PVP or CTAC or a mixture of the two; the reducing agent is citric acid monohydrate or sodium citrate.

The surfactant in step (1) is a mixture of PVP-8000 and CTAC; the reducing agent is citric acid monohydrate.

The metal platinum salt precursor solution is chloroplatinic acid or potassium chloroplatinate.

The metal ruthenium salt precursor solution is ruthenium trichloride.

Step (3) Stir at room temperature for 20 minutes, react in an autoclave for 2 hours, and control the temperature at about 210°C.

Beneficial effects of the present invention:

The present invention studies and obtains a PtRu binary metal nano-alloy catalyst with a flower-like (pore-like) structure, which better enhances the catalyst's ability to resist CO poisoning and improves the catalytic activity of methanol, formaldehyde and formic acid. Taking methanol as an example, the peak current value of catalytic methanol is 10.98mA cm-2.

The peak current value after sweeping for 3600 s at 0.6 v is 2.85 mA cm-2, which is more than ten times higher than the 0.21 mA cm-2 of commercial Pt black.

Description of drawings

Figure 1. It is a PtRu binary alloy nanocatalyst with a flower-like (pore-like) structure, and the result of observation with a high-resolution transmission electron microscope;

Figure 2 is the PtRu element spectrum of the flower-like (pore-like) structure. It can be seen that the overall distribution of Pt and Ru atoms in the flower-like (pore-like) structure particles is relatively uniform, forming an alloy;

Figure 3. Cyclic voltammetry curves of PtRu binary alloy nanocatalysts with flower-like (pore-like) structure and commercial Pt black, PtRu black and PtRu/C black in 0.1M HClO4+0.5M CH3OH solution;

Figure 4. The i-t curves of PtRu alloy nanocatalysts with flower-like (porous) structure and commercial Pt black, PtRu black and PtRu/C black in 0.1M HClO4+0.5M CH3OH solution at 0.6 v;

Figure 5. Cyclic voltammetry curves of PtRu binary alloy nanocatalysts with flower-like (pore-like) structure and commercial Pt black, PtRu/C black in 0.1M HClO4+0.1M HCHO solution to catalyze formaldehyde;

Figure 6. Cyclic voltammetry curves of PtRu binary alloy nanocatalysts with flower-like (porous) structure and commercial Pt black and PtRu/C black in 0.1M HClO4+0.1M HCOOH solution for formic acid.

Detailed ways

Specific implementation 1:

(1) Add the surfactant and the reducing agent into the aqueous solution at a mass ratio of 2:3, and stir for 15 minutes;

(2) Add chloroplatinic acid solution and ruthenium trichloride solution with a volume ratio of 3:2 to the mixed solution (5.6mL) in step (1), both at a concentration of 0.1mol/L, and the color of the mixed solution is yellow-brown , stirring at room temperature for 15 minutes;

(3) Transfer the solution obtained in step (2) into the reactor, react for 2 hours, and control the temperature at about 200°C;

(4) The obtained product is separated by centrifugation and washed three times with alcohol solution, and then dispersed and stored in alcohol solution, with good dispersibility and general catalytic activity.

Specific implementation 2:

(1) Add the surfactant and the reducing agent into the aqueous solution at a mass ratio of 2:3, and stir for 20 minutes;

(2) Add chloroplatinic acid solution and ruthenium trichloride solution with a volume ratio of 1:1 to the mixed solution (5.6mL) in step (1), both at a concentration of 0.1mol/L, and the color of the mixed solution is yellowish brown , stirred at room temperature for 20 minutes;

(3) Transfer the solution obtained in step (2) into the reactor, react for 2 hours, and control the temperature at about 210°C;

(4) After being centrifuged and washed three times with alcohol solution, the obtained product is dispersed and stored in alcohol solution, with good dispersibility and high catalytic ability.

Specific implementation 3:

(1) Add the surfactant and the reducing agent into the aqueous solution at a mass ratio of 2:3, and stir for 25 minutes;

(2) Add chloroplatinic acid solution and ruthenium trichloride solution with a volume ratio of 2:3 to the mixed solution (5.6mL) in step (1), both at a concentration of 0.1mol/L, and the color of the mixed solution is dark brown , stirring at room temperature for 25 minutes;

(3) Transfer the solution obtained in step (2) into the reactor, react for 2 hours, and control the temperature at about 220°C;

(4) The product obtained is centrifuged and washed three times with alcohol solution, and then dispersed and stored in alcohol solution, with good dispersibility and high catalytic activity.

Fig. 1 is a high-resolution transmission electron microscope of the catalyst obtained in the embodiment, and it can be seen that the flower-like (pore-like) structure of the PtRu binary alloy nanocatalyst.

Figure 2 is the PtRu element spectrum of the flower-like (pore-like) structure. It can be seen that the overall distribution of Pt and Ru atoms in the flower-like (pore-like) structure particles is uniform, forming an alloy.

Fig. 3. is the cyclic voltammetry curve of catalytic methanol in 0.1M HClO4+0.5M CH3OH solution for the catalyst obtained by the embodiment and commercial Pt black, PtRu black, PtRu/C black, can find out the peak of the PtRu wherein flower-like structure The highest current value is 10.98 mA cm-2.

Fig. 4. measures i-t curve under the condition of 0.6v in 0.1MHClO4+0.5MCH3OH solution for Pt black, PtRu black, PtRu/C black of embodiment gained catalyst and business, and test time is 3600 s, and the result shows the flower-like structure The peak current value of the PtRu catalyst at 3600 s has always been higher than that of Pt black, PtRu black and PtRu/C black, and its stability is better than that of commercial Pt black, PtRu black and PtRu/C black.

Fig. 5. is the cyclic voltammetry curve of the catalyst obtained in the embodiment and commercial Pt black, PtRu/C black in 0.1M HClO4+0.1M HCHO solution to catalyze formaldehyde. Among them, PtRu with flower-like structure has the highest peak current value of 12.16 mA cm-2.

Figure 6. is the cyclic voltammetry curve of the catalyst obtained in the embodiment and commercial Pt black, PtRu/C black in 0.1M HClO4+0.1M HCOOH solution catalyzed formic acid, wherein the peak current value of the PtRu of flower-like (porous) structure The highest is 6.42 mA cm-2.

Claims (8)

1. a PtRu binary metal nano-alloy catalyst of a flower-like (porous) structure, characterized in that: (1) Add surfactant and reducing agent into water together, stir at room temperature for 10 to 30 minutes, the mass ratio of surfactant to reducing agent is 1:2 to 2:1; the amount of water added needs to be equal to surfactant and The reducing agent is completely dissolved; (2) Add metal platinum salt precursor solution and metal ruthenium salt precursor solution respectively to the mixed solution obtained in step (1), the volume ratio of the two is: 3:2～2:3, the mixed solution and the metal precursor solution The ratio of the total volume is 10:1-20:1; stirring at room temperature for 10-30 minutes, the concentration of the metal salt precursor solution is 0.05-0.5mol/L; (3) Stir the mixed solution obtained in step (2) at room temperature for 5-30 minutes, react in an autoclave for 1.5-3 hours, and control the temperature at 180-230°C; (4) The product obtained in step (3) is cooled, washed, and centrifuged to obtain a PtRu binary metal nano-alloy catalyst with a flower-like (pore-like) structure. 2. the preparation method of the PtRu nano-alloy catalyst of a kind of flower shape (porous) structure according to claim 1, it is characterized in that: the aqueous solution described in step (1) is ultrapure water, and stirring time is 20 minutes, and surface The mass ratio of active agent to reducing agent is 2:3. 3. The preparation method of a PtRu nano-alloy catalyst with a flower-like (porous) structure according to claim 1, characterized in that: the surfactant in step (1) is PVP or CTAC or a mixture of the two; the reducing agent It is citric acid monohydrate or sodium citrate. 4. The preparation method of a PtRu nano-alloy catalyst with a flower-like (porous) structure according to claim 1 or 3, characterized in that: the surfactant in step (1) is a mixture of PVP-8000 and CTAC; The reducing agent is citric acid monohydrate. 5. The preparation method of a PtRu nano-alloy catalyst with a flower-like (porous) structure according to claim 1, characterized in that: the metal platinum salt precursor solution is chloroplatinic acid or potassium chloroplatinate. 6. The preparation method of a PtRu nano-alloy catalyst with a flower-like (pore-like) structure according to claim 1, characterized in that: the metal ruthenium salt precursor solution is ruthenium trichloride. 7. The preparation method of a PtRu nano-alloy catalyst with a flower-like (pore-like) structure according to claim 1, characterized in that: step (3) stirs at room temperature for 20 minutes, reacts in an autoclave for 2 hours, The temperature is controlled at about 210°C. 8. The PtRu binary metal nano-alloy catalyst according to claims 1-7 has relatively good catalytic efficiency and anti-poisoning performance to small organic molecules such as methanol, formaldehyde and formic acid in the field of fuel cells.