阅读说明：本技术 一种多孔电极离聚物覆盖度标定方法 (Porous electrode ionomer coverage calibration method ) 是由 王素力 孙瑞利 孙公权 于 2019-10-16 设计创作，主要内容包括：一种多孔电极离聚物覆盖度标定方法,用于测试燃料电池多孔电极电催化剂表面离聚物覆盖度。所述多孔电极包括电催化剂和离聚物,电催化剂附着有离聚物,通过TPR表征多孔电极和多孔电极中催化剂的比表面积,并通过计算得到。本发明适用于多种不同种类燃料电池中多孔电极离聚物覆盖度的标定。(A porous electrode ionomer coverage calibration method is used for testing the ionomer coverage of the surface of an electrocatalyst of a porous electrode of a fuel cell. The porous electrode comprises an electrocatalyst and an ionomer, the electrocatalyst is attached with the ionomer, the TPR represents the specific surface areas of the porous electrode and the catalyst in the porous electrode, and the specific surface areas are obtained through calculation. The method is suitable for calibrating the coverage of the porous electrode ionomer in various fuel cells of different types.)

1. A porous electrode ionomer coverage calibration method, wherein a porous electrode comprises an electrocatalyst and an ionomer, the electrocatalyst is attached with the ionomer, and the method is characterized in that: comprises the following steps

The method comprises the following steps: placing a porous electrode sample to be tested in a sample tube of a TPR test platform, introducing hydrogen into the sample tube, reacting at the temperature of 80-400 ℃ for 0.5-3h, cooling the sample tube to-100-25 ℃, and continuously keeping the introduction of the hydrogen for 0.5-1 h;

step two: feeding inert gas containing carbon monoxide with a volume concentration of 3-5% in batches by adopting a pulse feeding mode, recording the signal change after the inert gas containing carbon monoxide enters each time by using a testing instrument until the peak area change error of three continuous signals is within 3-5%, and respectively recording the peak area of each signal peak;

step three: replacing different samples of the same porous electrode to be tested, and repeating the testing process of the first step and the second step; repeating for more than 2 times;

step four: obtaining the specific surface area of the same porous electrode sample through a TPR test platform, and taking the average value of the test results of more than 3 times as ECSA_CO(m²/g)；

Step five: taking the electrocatalyst adopted by the porous electrode to be detected as a sample, repeating the steps from the first step to the fourth step to obtain the specific surface area of the electrocatalyst, and marking as ECSA₁(m²/g)；

Step six: the ionomer coverage is calculated by the formula

Wherein ECSA_COElectrochemical specific surface area (m) of porous electrode calibrated for this test method²/g)，ECSA₁Electrochemical surface area (m) of electrocatalyst used for porous electrode calibrated for this test method²/g)。

2. The method for calibrating ionomer coverage of a porous electrode of claim 1, wherein:

the flow rate of the gas flow in the first step and the second step is 100-150ml min^-1(ii) a And step two, the inert gas is one or two of helium or argon.

3. The method for calibrating ionomer coverage of a porous electrode of claim 1, wherein:

and in the second step, the volume of the pulse gas introduced each time is 50-250 mu L.

4. The method for calibrating ionomer coverage of a porous electrode of claim 1, wherein:

the sample tube can be cooled to 25 ℃ by adopting natural cooling, and can be cooled to less than 25 ℃ by adopting liquid nitrogen.

5. The method for calibrating ionomer coverage of a porous electrode of claim 1, wherein: the electrocatalyst is an electrocatalyst capable of chemisorbing carbon monoxide gas.

6. The method for calibrating ionomer coverage of a porous electrode of claim 1, wherein: step one, the mass of the porous electrode sample to be detected is 0.002-0.5 g.

Technical Field

The invention relates to the field of fuel cells, in particular to a porous electrode ionomer coverage calibration method.

Background

The polymer electrolyte membrane fuel cell has the advantages of energy conversion efficiency, environmental friendliness, quick start and the like, so that the polymer electrolyte membrane fuel cell has wide application prospect, but the cost of the electrode, particularly the cost of the electrocatalyst, still restricts the commercial application of the polymer electrolyte membrane fuel cell. To address such challenges, two solutions have been mainly adopted to design high activity electrocatalysts (platinum-based and non-platinum-based electrocatalysts) and to optimize electrode structures. For a high-activity electrocatalyst, the problems of poor electrode stability and activity and the like exist when the high-activity electrocatalyst is prepared into an electrode for testing. Therefore, it is a main research direction of porous electrodes to improve the utilization rate of porous electrode catalysts and reduce the cost of the catalysts from the beginning of electrode structures.

The space scale of the porous electrode spans two ranges of mesoscopic and microscopic; the mesoscale structure formed by the electrocatalyst and the ionomer aggregate directly influences the porous electrode material transfer process, and the interface structure of the electrocatalyst and the ionomer mainly influences the electrode reaction process and determines the performance of the porous electrode. Therefore, the research on the structural characteristics, particularly the interface structural characteristics, of the electrocatalyst and the ionomer in the porous electrode is very important for improving the performance of the porous electrode. At present, people mainly adopt a molecular dynamics simulation method, a two-dimensional plane electrode method and the like to research the characteristics of an interface structure formed by an ionomer and an electrocatalyst (the coverage of the ionomer on the surface of the electrocatalyst, the coverage of the ionomer on the surface of the electrocatalyst and the like). However, the interface structure described by these methods deviates from the actual situation of the porous electrode, so it is necessary to design a new method for testing the interface characteristics of the porous electrode, such as the coverage of the ionomer on the surface of the electrocatalyst.

Disclosure of Invention

The invention aims to provide a porous electrode ionomer coverage calibration method which is used for testing the ionomer coverage of the surface of an electrocatalyst of a porous electrode of a fuel cell.

A porous electrode ionomer coverage calibration method, wherein a porous electrode comprises an electrocatalyst and an ionomer, the electrocatalyst is attached with the ionomer, and the method is characterized in that: comprises the following steps of (a) carrying out,

the method comprises the following steps: placing 0.002-0.5g of porous electrode sample to be tested in a sample tube of a TPR test platform, introducing hydrogen into the sample tube, reacting at the temperature of 80-400 ℃ for 0.5-3h, cooling the sample tube to-100-25 ℃, and continuously keeping the introduction of the hydrogen for 0.5-1 h;

step two: feeding inert gas containing carbon monoxide with a volume concentration of 3-5% in batches by adopting a pulse feeding mode, recording the signal change after the inert gas containing carbon monoxide enters each time by using a testing instrument until the peak area change error of three continuous signals is within 3-5%, and respectively recording the peak area of each signal peak;

the volume of the pulse gas introduced each time is 50-250 mu L;

step three: replacing different samples of the same porous electrode to be tested, and repeating the testing process of the first step and the second step; repeating for more than 2 times;

step four: through TPR test platformObtaining the specific surface area of the same porous electrode sample, taking the average value of the test results of more than 3 times, and recording the average value as ECSA_CO(m²/g)；

Step five: taking the electrocatalyst adopted by the porous electrode to be detected as a sample, repeating the steps from the first step to the fourth step to obtain the specific surface area of the electrocatalyst, and marking as ECSA₁(m²/g)；

Step six: the ionomer coverage is calculated by the formula

Wherein ECSA_COElectrochemical specific surface area (m) of porous electrode calibrated for this test method²/g)，ECSA₁Electrochemical surface area (m) of electrocatalyst used for porous electrode calibrated for this test method²/g)。

The porous electrode ionomer coverage calibration method is characterized by comprising the following steps:

the flow rate of the gas flow in the first step and the second step is 100-150ml min^-1(ii) a And in the second step, the inert gas is one or two of helium, argon and the like.

The porous electrode ionomer coverage calibration method is characterized by comprising the following steps:

the sample tube can be cooled to 25 ℃ by adopting natural cooling, and can be cooled to less than 25 ℃ by adopting liquid nitrogen.

The porous electrode ionomer coverage calibration method is characterized by comprising the following steps: the electrocatalyst is an electrocatalyst capable of chemisorbing carbon monoxide gas.

The testing method has the characteristics of simplicity, convenience, easiness in implementation and the like, and has a wide application prospect in the field of fuel cells.