CN111987328A

CN111987328A - Preparation method of electrocatalyst with nanoparticle structure for methanol fuel cell

Info

Publication number: CN111987328A
Application number: CN202010828007.8A
Authority: CN
Inventors: 常方方; 任梦云; 杨林; 白正宇; 张庆
Original assignee: Henan Normal University
Current assignee: Henan Normal University
Priority date: 2020-08-17
Filing date: 2020-08-17
Publication date: 2020-11-24

Abstract

The invention discloses a preparation method of an electrocatalyst with a nanoparticle structure for a methanol fuel cell, which comprises the steps of dissolving platinum acetylacetonate, copper acetylacetonate, hexadecyl trimethyl ammonium chloride and glucose in oleylamine, stirring and mixing uniformly at room temperature, transferring to a high-pressure reaction kettle, reacting for 8 hours at 180 ℃, washing obtained black precipitate for 3-4 times by using absolute ethyl alcohol after the reaction is finished to obtain a pure PtCu alloy nanoparticle catalyst, and ultrasonically dispersing the PtCu alloy nanoparticle catalyst in an ethanol solution to obtain a standby solution. The synthetic method of the alcohol fuel cell electrocatalyst with the nanowire structure is simple to operate, high in reaction efficiency and low in energy consumption; the PtCu alloy nanoparticle catalyst has a large specific surface area, active sites are exposed more, and the PtCu alloy nanoparticle catalyst can be in better contact with electrolyte, so that the electrocatalytic activity of the catalyst can be effectively improved.

Description

Preparation method of electrocatalyst with nanoparticle structure for methanol fuel cell

Technical Field

The invention belongs to the technical field of fuel cell catalysts, and particularly relates to a preparation method of an electrocatalyst with a nanoparticle structure for a methanol fuel cell.

Background

With the development of society, environmental issues have received much attention, and there is an urgent need for a clean energy source to replace the conventional fossil fuels. Direct Methanol Fuel Cells (DMFCs) have become promising green energy devices with the advantages of high energy density, low pollutant emissions, and are ideal candidates for alternative fossil energy. In alcohol fuel cells, catalysts are important components and are key materials for determining the performance of alcohol fuel cells. In recent years, platinum has been considered the most suitable alcohol fuel cell catalyst because of its high activity and stability, particularly in acidic media. But its prospect in practical application is not optimistic due to its high price. Therefore, some inexpensive metals such as: copper, iron, cobalt and the like are used for reducing the dosage of platinum, and the effective improvement of the catalytic performance of the catalyst is an effective solution based on a dual-function mechanism.

Platinum is considered to be the most active cathode electrocatalyst of a fuel cell, however, during the electro-oxidation process, CO molecules are produced as intermediates, which can be adsorbed on the Pt surface and hardly removed. Therefore, the surface poisoning of Pt by CO inhibits catalytic activity, and this problem must be solved to realize a highly efficient and stable Pt catalyst. Electro-oxidation of methanol on Pt is carried out in three steps, first adsorption of methanol; pt subsequently breaks the C-H bond of methanol and then CO molecules will adsorb on the Pt surface, which is considered a dehydrogenation step; the final CO is oxidized with the aid of oxygen-containing species (e.g., -OH) formed on the Pt. However, oxygen-containing species typically adhere to Pt surfaces at high potentials. Therefore, in the low potential state, the adsorbed CO molecules are difficult to remove, resulting in poor activity of the Pt catalyst. The introduction of a second or third metal, such as Ni, Au, Ru, Sn, Co or Cu, is an effective method to release the Pt surface from Co adsorption. In this bimetallic system, Pt plays a key role in the adsorption and dehydrogenation of methanol. On the other hand, the second metal may provide an oxygen-containing species as a promoter of low potential CO oxidation. The second metal may also alter the electronic structure of Pt by transferring electrons from the second metal to Pt, thereby weakening the Pt-CO bonding energy.

Energy is one of the biggest challenges in the 21 st century. To reduce human dependence on fossil fuels, the development of sustainable energy technology is a very important research. Direct Methanol Fuel Cells (DMFCs) and Direct Ethanol Fuel Cells (DEFCs) have attracted continuous attention over the last several decades as clean energy sources with great potential, and alcohol fuel cells have many advantages such as high energy conversion efficiency, low emissions, easy storage, and the like. In view of the activity and stability of metallic Pt, Pt nanocrystals are the most common alcohol fuel cell catalyst due to their higher catalytic activity and stability.

Disclosure of Invention

The invention solves the technical problem of providing a preparation method of an electrocatalyst with a nanoparticle structure for a methanol fuel cell, which is used for effectively improving the catalytic performance of an alcohol fuel cell catalyst.

The invention adopts the following technical scheme for solving the technical problems, and the preparation method of the electrocatalyst with the nanoparticle structure for the methanol fuel cell is characterized by comprising the following specific processes:

step S1: dissolving platinum acetylacetonate, copper acetylacetonate, cetyltrimethylammonium chloride (CTAC) and glucose in oleylamine, stirring and mixing uniformly at room temperature, transferring to a high-pressure reaction kettle, reacting for 8 hours at 180 ℃, washing the obtained black precipitate for 3-4 times by using absolute ethyl alcohol after the reaction is finished to obtain a pure PtCu alloy nanoparticle catalyst, and ultrasonically dispersing the PtCu alloy nanoparticle catalyst in an ethanol solution to obtain a standby solution;

step S2: adding XC-72 carbon black into the standby liquid obtained in the step S1, stirring and dispersing uniformly, standing at room temperature, sucking out supernatant liquid after the supernatant liquid is clarified, and drying the black precipitate precipitated to the bottom in a vacuum drying oven at 40-60 ℃ until the solvent is completely volatilized to obtain the PtCu alloy nanoparticle catalyst loaded on the carbon black.

Further, the preparation method of the electrocatalyst with a nanoparticle structure for the methanol fuel cell is characterized by comprising the following specific steps:

step S1: dissolving 25.1mg of platinum acetylacetonate, 67mg of copper acetylacetonate, 0.2g of hexadecyltrimethylammonium chloride and 0.2g of glucose in 30mL of oleylamine, stirring and mixing uniformly at room temperature, transferring the mixture to a high-pressure reaction kettle, reacting for 8 hours at 180 ℃, washing the obtained black precipitate for 3-4 times by using absolute ethyl alcohol after the reaction is finished to obtain a pure PtCu alloy nanoparticle catalyst, wherein the average particle size of the PtCu alloy nanoparticle catalyst is 9.5 +/-2.5 nm, and ultrasonically dispersing the PtCu alloy nanoparticle catalyst in an ethanol solution to obtain a standby solution;

step S2: adding XC-72 carbon black into the standby liquid obtained in the step S1, stirring and dispersing uniformly, standing at room temperature, sucking out supernatant liquid after the supernatant liquid is clarified, and drying the black precipitate precipitated to the bottom in a vacuum drying oven at 50 ℃ until the solvent is completely volatilized to obtain the PtCu alloy nanoparticle catalyst loaded on the carbon black.

step S1: dissolving 52.7mg of platinum acetylacetonate, 42.5mg of copper acetylacetonate, 0.2g of hexadecyl trimethyl ammonium chloride and 0.2g of glucose in 30mL of oleylamine, stirring and mixing uniformly at room temperature, transferring the mixture to a high-pressure reaction kettle, reacting for 8 hours at 180 ℃, washing the obtained black precipitate for 3-4 times by using absolute ethyl alcohol after the reaction is finished to obtain a pure PtCu alloy nanoparticle catalyst, wherein the average particle size of the PtCu alloy nanoparticle catalyst is 9.0 +/-1.3 nm, and ultrasonically dispersing the PtCu alloy nanoparticle catalyst in an ethanol solution to obtain a standby solution;

step S1: dissolving 76.2mg of platinum acetylacetonate, 27.9mg of copper acetylacetonate, 0.2g of hexadecyl trimethyl ammonium chloride and 0.2g of glucose in 30mL of oleylamine, stirring and mixing uniformly at room temperature, transferring the mixture to a high-pressure reaction kettle, reacting for 8 hours at 180 ℃, washing for 3-4 times by using absolute ethyl alcohol after the reaction is finished to obtain a pure PtCu alloy nanoparticle catalyst, wherein the average particle size of the PtCu alloy nanoparticle catalyst is 9.7 +/-1.8 nm, and ultrasonically dispersing the PtCu alloy nanoparticle catalyst in an ethanol solution to obtain a standby solution;

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

1. the synthetic method of the alcohol fuel cell electrocatalyst with the nanoparticle structure is simple to operate, high in reaction efficiency and low in energy consumption.

2. In the invention, the PtCu alloy nanoparticle catalyst has larger specific surface area, more exposed active sites and better contact with electrolyte, and can effectively improve the electrocatalytic activity of the catalyst.

3. In the invention, CTAC plays a very key role in the formation process of the nanoparticle catalyst, and the existence of CTAC means the generation of nanoparticles.

4. The invention realizes the comprehensive control of the components, the appearance, the size and the phase structure of the platinum-copper alloy nanowire and has more comprehensive and deep knowledge on the physical characteristics of the nanowire. The influence of the glucose dosage, the reaction temperature, the reaction time and other conditions in the initial reaction solution on the growth process and the final morphology of the nanoparticles is explored, and the optimal synthesis conditions of the nanoparticles are determined. On the basis, the growth mechanism of the strain is researched and analyzed. So that the fuel cell has bright prospect in the field of fuel cells.

Drawings

Fig. 1 is a TEM image of PtCu alloy nanoparticle catalysts prepared in examples 1 to 3 of the present invention;

FIG. 2 is a TEM image of a product obtained in comparative example 1 of the present invention;

fig. 3 is a graph of methanol oxidation performance of PtCu alloy nanoparticle catalysts prepared in examples 1 to 3 of the present invention and Pt nanoparticle catalyst of comparative example 1.

Detailed Description

The present invention is described in further detail below with reference to examples, but it should not be construed that the scope of the above subject matter of the present invention is limited to the following examples, and that all the technologies realized based on the above subject matter of the present invention belong to the scope of the present invention.

Example 1

Step S1: dissolving 25.1mg of platinum acetylacetonate, 67mg of copper acetylacetonate, 0.2g of hexadecyl trimethyl ammonium chloride and 0.2g of glucose in 30mL of oleylamine, stirring and mixing uniformly at room temperature, transferring the mixture to a high-pressure reaction kettle, reacting for 8 hours at 180 ℃, washing the obtained black precipitate for 3-4 times by using absolute ethyl alcohol after the reaction is finished to obtain a pure PtCu alloy nanoparticle catalyst, and ultrasonically dispersing the PtCu alloy nanoparticle catalyst in an ethanol solution to obtain a standby solution;

step S2: adding XC-72 carbon black into the standby liquid obtained in the step S1, stirring and dispersing uniformly, standing at room temperature, sucking out supernatant liquid after the supernatant liquid is clarified, and drying the black precipitate precipitated to the bottom in a vacuum drying oven at 50 ℃ until the solvent is completely exerted to obtain the PtCu alloy nanoparticle catalyst loaded on the carbon black. From fig. 1, it can be known that the particle size of the PtCu alloy nanoparticle catalyst prepared in this embodiment is between 9.5 ± 2.5 nm.

4mg of the PtCu alloy nanoparticle catalyst prepared in the embodiment is dispersed in a dispersing agent, the mixed solution is ultrasonically and uniformly coated on the surface of a glassy carbon electrode, a three-electrode system is adopted, the performance of the catalyst is measured through an electrochemical workstation, and the electrical property test result is shown as a curve a in FIG. 3.

Example 2

Step S1: dissolving 52.7mg of platinum acetylacetonate, 42.5mg of copper acetylacetonate, 0.2g of hexadecyl trimethyl ammonium chloride and 0.2g of glucose in 30mL of oleylamine, stirring and mixing uniformly at room temperature, transferring the mixture to a high-pressure reaction kettle, reacting for 8 hours at 180 ℃, washing the obtained black precipitate with absolute ethyl alcohol for 3-4 times after the reaction is finished to obtain a pure PtCu alloy nanoparticle catalyst, and ultrasonically dispersing the PtCu alloy nanoparticle catalyst in an ethanol solution to obtain a standby solution;

step S2: adding XC-72 carbon black into the standby liquid obtained in the step S1, stirring and dispersing uniformly, standing at room temperature, sucking out supernatant liquid after the supernatant liquid is clarified, and drying the black precipitate precipitated to the bottom in a vacuum drying oven at 50 ℃ until the solvent is completely volatilized to obtain the PtCu alloy nanoparticle catalyst loaded on the carbon black. From fig. 2, it can be known that the particle size of the PtCu alloy nanoparticle catalyst prepared in this embodiment is between 9.0 ± 1.3 nm.

4mg of the PtCu alloy nanoparticle catalyst prepared in the embodiment is dispersed in a dispersing agent, carbon black is added, the mixed solution is ultrasonically and uniformly coated on the surface of a glassy carbon electrode, a three-electrode system is adopted, the performance of the catalyst is measured through an electrochemical workstation, and the electrical performance test result is shown as a curve b in fig. 3.

Example 3

Step S1: dissolving 76.2mg of platinum acetylacetonate, 27.9mg of copper acetylacetonate, 0.2g of hexadecyl trimethyl ammonium chloride and 0.2g of glucose in 30mL of oleylamine, stirring and mixing uniformly at room temperature, transferring the mixture to a high-pressure reaction kettle, reacting for 8 hours at 180 ℃, washing for 3-4 times by using absolute ethyl alcohol after the reaction is finished to obtain a pure PtCu alloy nanoparticle catalyst, and ultrasonically dispersing the PtCu alloy nanoparticle catalyst in an ethanol solution to obtain a standby solution;

step S2: adding XC-72 carbon black into the standby liquid obtained in the step S1, stirring and dispersing uniformly, standing at room temperature, sucking out supernatant liquid after the supernatant liquid is clarified, and drying the black precipitate precipitated to the bottom in a vacuum drying oven at 50 ℃ until the solvent is completely volatilized to obtain the PtCu alloy nanoparticle catalyst loaded on the carbon black. From fig. 3, it can be known that the particle size of the PtCu alloy nanoparticle catalyst prepared in this embodiment is between 9.7 ± 1.8 nm.

4mg of the PtCu alloy nanoparticle catalyst prepared in the embodiment is dispersed in a dispersing agent, carbon black is added, the mixed solution is ultrasonically and uniformly coated on the surface of a glassy carbon electrode, a three-electrode system is adopted, the performance of the catalyst is measured through an electrochemical workstation, and the electrical performance test result is shown as a curve c in fig. 3.

Comparative example 1

Step S1: dissolving 117.9mg of platinum acetylacetonate and 0.8g of potassium hydroxide in a mixed solvent of 30mL of N, N-dimethylformamide and 20mL of ethylene glycol, stirring and mixing uniformly at room temperature, transferring the mixture to a high-pressure reaction kettle, reacting for 8 hours at 180 ℃, washing for 3-4 times by using absolute ethyl alcohol after the reaction is finished to obtain a pure Pt nanoparticle catalyst, and ultrasonically dispersing the Pt nanoparticle catalyst in an ethanol solution to obtain a standby solution;

step S2: adding XC-72 carbon black into the standby liquid obtained in the step S1, stirring and dispersing uniformly, standing at room temperature, sucking out supernatant liquid after the supernatant liquid is clarified, and drying the black precipitate precipitated to the bottom in a vacuum drying oven at 50 ℃ to obtain the Pt nanoparticle catalyst loaded on the carbon black. As can be seen from FIG. 2, the particle size of the Pt nanoparticle catalyst prepared in this example is 11.2. + -. 1.4 nm.

4mg of the Pt nanoparticle catalyst prepared in the comparative example is dispersed in a dispersing agent, carbon black is added, the mixed solution is ultrasonically and uniformly coated on the surface of a glassy carbon electrode, a three-electrode system is adopted, the performance of the catalyst is measured through an electrochemical workstation, and the electrical performance test result is shown as a curve d in figure 3.

The alcohol fuel cell catalyst prepared by the invention has good MOR electrocatalytic activity. In the results of the electrical property test of fig. 3, a to c are MOR polarization curves of the catalysts prepared in examples 1 to 3, respectively, and d is a MOR polarization curve of the catalyst prepared in comparative example 1, the catalysts prepared in examples showed higher MOR electrocatalytic activity compared to comparative example 1; the analysis shows that the PtCu alloy with the nanoparticle morphology has the synergistic effect between double metals and good CO poisoning resistance, is beneficial to electron transfer and mass transfer in the catalytic process, and can overcome the problems of migration, polymerization, Ostwald ripening and the like of Pt nanoparticles caused by carbon corrosion easily encountered by commercial Pt/C catalysts, thereby improving the methanol oxidation activity. The electrocatalytic activity of the battery catalyst prepared by the invention is excellent, and the battery catalyst is a fuel battery catalyst with wide application prospect.

While there have been shown and described what are at present considered the fundamental principles of the invention, its essential features and advantages, the invention further resides in various changes and modifications which fall within the scope of the invention as claimed.

Claims

1. A preparation method of an electrocatalyst with a nanoparticle structure for a methanol fuel cell is characterized by comprising the following specific steps:

step S1: dissolving platinum acetylacetonate, copper acetylacetonate, hexadecyl trimethyl ammonium chloride and glucose in oleylamine, stirring and mixing uniformly at room temperature, transferring the mixture to a high-pressure reaction kettle, reacting for 8 hours at 180 ℃, washing the obtained black precipitate for 3-4 times by using absolute ethyl alcohol after the reaction is finished to obtain a pure PtCu alloy nanoparticle catalyst, and ultrasonically dispersing the PtCu alloy nanoparticle catalyst in an ethanol solution to obtain a standby solution;

2. The preparation method of the electrocatalyst with a nanoparticle structure for a methanol fuel cell according to claim 1, comprising the following specific steps:

3. The preparation method of the electrocatalyst with a nanoparticle structure for a methanol fuel cell according to claim 1, comprising the following specific steps:

4. The preparation method of the electrocatalyst with a nanoparticle structure for a methanol fuel cell according to claim 1, comprising the following specific steps: