Gas diffusion electrode section in-situ Raman test system

Abstract

The invention provides a gas diffusion electrode section in-situ Raman test system. The gas diffusion electrode section in-situ Raman test system comprises a Raman spectrometer and an electrochemical reaction tank, the Raman spectrometer comprises a Raman lens; the electrochemical reaction tank comprises a gas flow field plate, a cathode flow field plate, an anode flow field plate, a liquid leakage prevention plate, a first light window, a second light window, a window sheet, a sealing gasket, a sealing plate, a first fastener, a second fastener, a gas diffusion electrode, an anode, a reference electrode and an ion exchange membrane. The test system provided by the invention can realize high-spatial-resolution in-situ Raman test of the section of the gas diffusion electrode, especially the section of the catalyst layer of the gas diffusion electrode.

Description

Technical Field

[0001] This application relates to the technical field of in-situ electrochemical characterization, and particularly to an in-situ Raman testing system for the cross-section of a gas diffusion electrode. Background Art

[0002] In the study of electrochemical reduction reactions, real-time monitoring and analysis of the reaction process are crucial. Although traditional electrochemical reaction cell designs can achieve multiphase reactions, they have limitations in in-situ characterization and it is difficult to accurately obtain information on changes at the reaction interface. Raman spectroscopy, as a non-destructive and in-situ analysis technique, can provide molecular vibration information and provide an important basis for studying reaction mechanisms. Therefore, how to design an electrochemical reaction cell and combine Raman spectroscopy technology with the electrochemical reaction cell to achieve in-situ testing of the electrochemical reduction reaction interface has become an urgent problem for those skilled in the art. Summary of the Invention

[0003] The purpose of this application is to provide an in-situ Raman testing system for the cross-section of a gas diffusion electrode to achieve in-situ Raman testing with high spatial resolution of the cross-section of the gas diffusion electrode, especially the catalyst layer cross-section of the gas diffusion electrode. The specific technical solutions are as follows:

[0004] The first aspect of this application provides an in-situ Raman testing system for the cross-section of a gas diffusion electrode, which includes a Raman spectrometer and an electrochemical reaction cell; the Raman spectrometer includes a Raman lens; the electrochemical reaction cell includes a gas flow field plate, a cathode flow field plate, an anode flow field plate, a liquid leakage prevention plate, a first optical window, a second optical window, a window piece, a sealing gasket, a sealing plate, a first fastener, a second fastener, a gas diffusion electrode, an anode, a reference electrode, and an ion exchange membrane; the gas flow field plate, the gas diffusion electrode, the cathode flow field plate, the ion exchange membrane, the anode flow field plate, the anode, and the liquid leakage prevention plate are arranged in sequence along a first direction and are connected and sealed by the first fastener; the Raman lens, the sealing plate, and the sealing gasket are arranged in sequence along a second direction perpendicular to the first direction; the first optical window is arranged above the top surface of the gas flow field plate and the cathode flow field plate perpendicular to the second direction, the first optical window cooperates with the sealing gasket, and the window piece cooperates with the first optical window; the second optical window is arranged on the sealing plate, and the sealing gasket, the sealing plate, the gas flow field plate, and the cathode flow field plate are connected and sealed by the second fastener; the reference electrode is arranged on the cathode flow field plate; the Raman laser emitted by the Raman spectrometer can pass through the Raman lens along the second direction, pass through the second optical window and the first optical window, and reach the cross-section of the gas diffusion electrode.

[0005] In some embodiments of the present application, a first cavity is provided inside the gas flow field plate. The third direction is perpendicular to the first direction and the second direction. On two opposite surfaces of the gas flow field plate perpendicular to the third direction, first flow channels communicating with the first cavity are provided. On a first surface of the gas flow field plate perpendicular to the first direction, a first groove communicating with the first cavity is provided; a second cavity is provided inside the cathode flow field plate. On two opposite surfaces of the cathode flow field plate perpendicular to the third direction, second flow channels communicating with the second cavity are provided. On a second surface of the cathode flow field plate perpendicular to the first direction, a second groove communicating with the second cavity is provided. On opposite surfaces of the top surface of the cathode flow field plate, internal threads communicating with the second cavity are provided; a third cavity is provided inside the anode flow field plate. On two opposite surfaces of the anode flow field plate perpendicular to the third direction, third flow channels communicating with the third cavity are provided.

[0006] In some embodiments of the present application, the gas diffusion electrode is disposed between the first surface and the second surface.

[0007] In some embodiments of the present application, the reference electrode is disposed in the internal threads.

[0008] In some embodiments of the present application, the first groove and the second groove are equal in size.

[0009] In some embodiments of the present application, a first through hole mating with the first fastener is provided on the first surface of the gas flow field plate. A second through hole mating with the first fastener is provided on the second surface of the cathode flow field plate. A third through hole mating with the first fastener is provided on a surface of the anode flow field plate perpendicular to the first direction. A fourth through hole mating with the first fastener is provided on a surface of the liquid leakage prevention plate perpendicular to the first direction.

[0010] In some embodiments of the present application, a fifth through hole mating with the second fastener is provided on the top surface of the gas flow field plate. A sixth through hole mating with the second fastener is provided on the top surface of the cathode flow field plate. A seventh through hole mating with the second fastener is provided on the sealing plate. An eighth through hole mating with the second fastener is provided on the sealing gasket.

[0011] In some embodiments of the present application, the Raman lens is movable.

[0012] In some embodiments of the present application, the material of the window pane is any one of quartz and calcium fluoride.

[0013] A second aspect of the present application provides a use of the testing system provided in the first aspect of the present application for testing the in-situ Raman of the cross-section of a gas diffusion electrode.

[0014] Advantages of the present application:

[0015] The present application provides an in-situ Raman testing system for the cross-section of a gas diffusion electrode, which includes a Raman spectrometer and an electrochemical reaction cell; the Raman spectrometer includes a Raman lens; the electrochemical reaction cell includes a gas flow field plate, a cathode flow field plate, an anode flow field plate, a liquid leakage prevention plate, a first optical window, a second optical window, a window piece, a sealing gasket, a sealing plate, a first fastener, a second fastener, a gas diffusion electrode, an anode, a reference electrode, and an ion exchange membrane. On the one hand, the electrochemical reaction cell is sealed for gas and liquid through the window piece, the sealing gasket, and the sealing plate, which can maintain a stable reaction environment and enable the electrochemical reaction to proceed stably. On the other hand, through the design of the first optical window and the second optical window, the Raman laser emitted by the Raman spectrometer can pass through the window piece to reach the cross-section of the gas diffusion electrode, enabling high-spatial-resolution detection of the cross-section of the catalyst layer on the gas diffusion electrode, improving the accuracy of the test, and further realizing real-time and accurate monitoring of the species on the cross-section of the catalyst layer during the electrochemical reaction process. Thus, minute changes and intermediate products during the reaction can be observed, and the reaction mechanism can be understood in depth. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following-described drawings are only some embodiments of the present application. For those of ordinary skill in the art, other embodiments can also be obtained based on these drawings.

[0017] Figure 1a Structural schematic diagram of the in-situ Raman testing system for the cross-section of a gas diffusion electrode according to an embodiment of the present application;

[0018] Figure 1b is Figure 1a structural breakdown diagram of;

[0019] Figure 2 a in Figure 1b front view along the first direction, Figure 2 b in

[0020] Figure 3 is Figure 1b left view of;

[0021] Figure 4 Potentiostatic test result diagram of the gas diffusion electrode in the testing system of Embodiment 1 of the present application;

[0022] Figure 5 In-situ Raman spectrogram of the cross-section of the gas diffusion electrode tested by the testing system of Embodiment 1 of the present application.

[0023] In the figure, 1. Electrochemical reaction cell, 111. Gas flow field plate, 112. Cathode flow field plate, 113. Anode flow field plate, 114. Liquid leakage prevention plate, 115. First optical window, 116. Second optical window, 117. Window piece, 118. Sealing gasket, 119. Sealing plate, 120. First fastener, 121. Second fastener, 122. Gas diffusion electrode, 123. Anode, 124. Reference electrode, 125. Ion exchange membrane, 126. First cavity, 127. First flow channel, 128. First groove, 129. Second cavity, 130. Second flow channel, 131. Second groove, 132. Internal thread, 133. Third cavity, 134. Third flow channel, 135. First through hole, 136. Second through hole, 137. Third through hole, 138. Fourth through hole, 139. Fifth through hole, 140. Sixth through hole, 141. Seventh through hole, 142. Eighth through hole, 2. Raman spectrometer, 211 Raman lens, X. First direction, Y. Second direction, Z. Third direction. Detailed implementation manners

[0024] Next, the technical solutions in the present application will be clearly and completely described in conjunction with the embodiments of the present application and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the present application belong to the scope of protection of the present application.

[0025] Currently, the main method for testing the electrochemical reduction reaction using Raman spectroscopy is to detect the solid-liquid interface by passing Raman laser through the electrolyte. This testing method cannot obtain the species distribution of the catalyst cross-section during the reaction, nor can it achieve spatial resolution. Based on this, the present application provides a gas diffusion electrode cross-section in-situ Raman testing system to achieve in-situ Raman testing with high spatial resolution of the gas diffusion electrode cross-section, especially the catalyst layer cross-section of the gas diffusion electrode.

[0026] The first aspect of the present application provides a gas diffusion electrode cross-section in-situ Raman testing system, as Figure 1a and Figure 1bAs shown in the figure, it includes a Raman spectrometer 2 and an electrochemical reaction cell 1; the Raman spectrometer 2 includes a Raman lens 211; the electrochemical reaction cell 1 includes a gas flow field plate 111, a cathode flow field plate 112, an anode flow field plate 113, a liquid leakage prevention plate 114, a first optical window 115, a second optical window 116, a window piece 117, a sealing gasket 118, a sealing plate 119, a first fastener 120, a second fastener 121, a gas diffusion electrode 122, an anode 123, a reference electrode 124, and an ion exchange membrane 125. The gas flow field plate 111, the gas diffusion electrode 122, the cathode flow field plate 112, the ion exchange membrane 125, the anode flow field plate 113, the anode 123, and the liquid leakage prevention plate 114 are arranged in sequence along the first direction X and are connected and sealed by the first fastener 120; the Raman lens 211, the sealing plate 119, and the sealing gasket 118 are arranged in sequence along the second direction Y perpendicular to the first direction X; the first optical window 115 is arranged above the top surface of the gas flow field plate 111 and the cathode flow field plate 112 perpendicular to the second direction Y, the first optical window 115 cooperates with the sealing gasket 118, and the window piece 117 cooperates with the first optical window 115; the second optical window 116 is arranged on the sealing plate 119, and the sealing gasket 118, the sealing plate 119, and the gas flow field plate 111, the cathode flow field plate 112 are connected and sealed by the second fastener 121; the reference electrode 124 is arranged on the cathode flow field plate 112. The Raman laser emitted by the Raman spectrometer 2 can pass through the Raman lens 211 along the second direction Y through the second optical window 116 and the first optical window 115 to reach the cross-section of the gas diffusion electrode 122. Through the design of the sealing window piece 117 at the cross-section of the gas diffusion electrode 122 of the electrochemical reaction cell 1, not only the gas-liquid sealing function of the electrochemical reaction cell 1 is realized to prevent cross-flow, but also the Raman laser emitted by the Raman spectrometer 2 can pass through the window piece 117 to reach the cross-section of the gas diffusion electrode 122, enabling real-time and high-spatial-resolution precise monitoring of the species at the cross-section of the catalyst layer during the electrochemical reaction process, and the spatial resolution can reach 4μm. In short, the test system of the present application provides an efficient and accurate monitoring means for the research of electrochemical reactions, helps to deeply understand the electrode structure, and promotes the technological development of related fields.

[0027] The in-situ Raman test system for the cross-section of the gas diffusion electrode of the present application can be used for the in-situ characterization of the cross-section of the catalyst layer of the gas diffusion electrode in the CO2 / CO electrochemical reduction reaction and fuel cells.

[0028] The present application has no special limitation on the structure of the gas diffusion electrode 122, as long as the purpose of the present application can be achieved. For example, the gas diffusion electrode 122 can be a three-layer structure including a gas diffusion layer, a catalyst layer, and a support layer, or a two-layer structure including a gas diffusion layer and a catalyst layer. The thickness of the catalyst layer of the gas diffusion electrode 122 of the present application is less than 50μm.

[0029] The gas diffusion electrode 122, anode 123, reference electrode 124, and ion exchange membrane 125 of the present application can be obtained by purchase, or can be prepared independently. Different gas diffusion electrodes 122, anodes 123, reference electrodes 124, and ion exchange membranes 125 can be selected according to different electrochemical reactions.

[0030] In some embodiments of the present application, such as Figure 1a , Figure 1b , Figure 2 and Figure 3 shown, a first cavity 126 is provided inside the gas flow field plate 111. The third direction Z is perpendicular to the first direction X and the second direction Y. First flow channels 127 communicating with the first cavity 126 are provided on two opposite surfaces of the gas flow field plate 111 perpendicular to the third direction Z. A first groove 128 communicating with the first cavity is provided on the first surface of the gas flow field plate 111 perpendicular to the first direction X; a second cavity 129 is provided inside the cathode flow field plate 112. Second flow channels 130 communicating with the second cavity 129 are provided on two opposite surfaces of the cathode flow field plate 112 perpendicular to the third direction Z. A second groove 131 communicating with the second cavity 129 is provided on the second surface of the cathode flow field plate 112 perpendicular to the first direction X; internal threads 132 communicating with the second cavity 129 are provided on opposite surfaces of the top surface of the cathode flow field plate 112; a third cavity 133 is provided inside the anode flow field plate 113. Third flow channels 134 communicating with the third cavity 133 are provided on two opposite surfaces of the anode flow field plate 113 perpendicular to the third direction Z. In some embodiments of the present application, the gas diffusion electrode 122 is disposed between the first surface and the second surface. In some embodiments of the present application, the reference electrode 124 is disposed in the internal threads 132. Through the three-layer flow channel design of the electrochemical reaction cell, the stratified flow of the reaction gas, cathode electrolyte, and anode electrolyte is realized. The reaction gas can enter the first cavity 126 through the first flow channels 127, the cathode electrolyte can enter the second cavity 129 through the second flow channels 130, and the anode electrolyte can enter the third cavity 133 through the third flow channels 134. The gas diffusion electrode 122, i.e., the cathode, is located between the reaction gas layer and the cathode electrolyte layer, and the anode 123 is located outside the anode electrolyte layer. The two are isolated by the ion exchange membrane 125, which is beneficial to preventing the oxidation loss of the cathode reduction product at the anode. The first groove 128 and the second groove 131 are used to place the gas diffusion electrode 122, which is beneficial to improving the sealing performance of the electrochemical reaction cell 1.

[0031] In some embodiments of the present application, such as Figure 1a and Figure 1bAs shown, a first through-hole 135 adapted to the first fastener 120 is provided on the first surface of the gas flow field plate 111, a second through-hole 136 adapted to the first fastener 120 is provided on the second surface of the cathode flow field plate 112, a third through-hole 137 adapted to the first fastener 120 is provided on the surface of the anode flow field plate 113 perpendicular to the first direction X, and a fourth through-hole 138 adapted to the first fastener 120 is provided on the surface of the liquid leakage prevention plate 114 perpendicular to the first direction X. Through the cooperation of the above through-holes and the first fastener 120, the positions of the gas diffusion electrode 122, the anode 123, and the ion exchange membrane 125 can be fixed, the airtightness and liquid tightness of the electrochemical reaction cell 1 can be improved, the leakage of the reaction gas can be avoided, and at the same time, the cross-flow of the electrolyte can be prevented, enabling the normal progress of the electrochemical reaction. In addition, the structure of the cooperation between the through-holes and the fasteners enables the electrochemical reaction cell to be detachable and easily assembled, facilitating the replacement of the electrodes.

[0032] In some embodiments of the present application, as Figure 1a and Figure 1b shown, a fifth through-hole 139 adapted to the second fastener 121 is provided on the top surface of the gas flow field plate 111, a sixth through-hole 140 adapted to the second fastener 121 is provided on the top surface of the cathode flow field plate 112, a seventh through-hole 141 adapted to the second fastener 121 is provided on the sealing plate 119, and an eighth through-hole 142 adapted to the second fastener 121 is provided on the sealing gasket 118. Through the cooperation of the above through-holes and the second fastener 121, the window pane 117 and the sealing gasket 118 can be pressed on the gas diffusion electrode 122, which is not only beneficial to improving the airtightness and liquid tightness of the electrochemical reaction cell 1, but also allows the Raman laser to pass through the window pane 117 to reach the cross-section of the gas diffusion electrode 122, thereby realizing the real-time and accurate monitoring of the species on the cross-section of the catalyst layer during the electrochemical reaction process.

[0033] In some embodiments of the present application, as Figure 1a and Figure 1b shown, the Raman lens 211 is movable. By moving the Raman lens 211, different positions of the cross-section of the gas diffusion electrode 122 during the electrochemical reaction process can be tested in real time, with high spatial resolution, which is beneficial to understanding the reaction principle.

[0034] In some embodiments of the present application, the material of the window pane 117 is any one of quartz and calcium fluoride. The above materials of the window pane 117 have excellent light transmittance, and the Raman laser can penetrate the window pane 117 to irradiate the cross-section of the gas diffusion electrode 122, thereby realizing the in-situ Raman test of the cross-section of the gas diffusion electrode 122.

[0035] The present application does not particularly limit the thickness of the window pane 117, as long as the object of the present application can be achieved. For example, the thickness of the window pane 117 can be 500 μm.

[0036] The second aspect of the present application provides a use of the test system provided in the first aspect of the present application for testing the cross-section in-situ Raman of a gas diffusion electrode.

[0037] Examples

[0038] Hereinafter, examples and comparative examples are given to illustrate the embodiments of the present application more specifically. Various tests and evaluations are carried out according to the following methods. In addition, unless otherwise specified, "parts" and "%" are based on mass.

[0039] Example 1

[0040] <In-situ Raman Test of the Cross-section of the Gas Diffusion Electrode for the CO2 / CO Electrochemical Reduction Reaction>

[0041] Prepare the cathode electrolyte and the anode electrolyte:

[0042] Add 0.005 M H2SO4 solution to 0.5 M K2SO4 solution to adjust the solution pH to 2 to obtain the cathode electrolyte and the anode electrolyte.

[0043] Assemble the test system:

[0044] Press Figure 1a , Figure 1b As shown, assemble the test system, where the window 117 uses a quartz window with a thickness of about 500 μm, the ion exchange membrane 125 is a PiperION membrane (Versogen, USA, anion exchange membrane) with a thickness of about 20 μm; the anode 123 is iridium oxide supported on titanium felt with a thickness of about 500 μm; the reference electrode 124 is a silver / silver chloride reference electrode; the electrode gas diffusion electrode 122 is composed of a gas diffusion layer carbon paper with a thickness of about 300 μm and a catalyst layer with a thickness of about 20 μm. The catalyst layer contains copper micro-particles with a particle size of 0.5 μm to 1.5 μm. Since it is exposed to air, a part of the copper on the surface of the catalyst layer will be oxidized to form cuprous oxide. During assembly, the carbon paper contacts the gas flow field plate 111, and the catalyst layer contacts the cathode flow field plate 112.

[0045] Constant potential (CA) test:

[0046] After assembly, the reaction gas CO2 is introduced into the gas flow field plate 111, the above-prepared mixed solution of K2SO4 and H2SO4 with a pH of 2 is introduced into the cathode flow field plate 112 as the cathode electrolyte, and the above-prepared mixed solution of K2SO4 and H2SO4 with a pH of 2 is introduced into the anode flow field plate 113 as the anode electrolyte. Connect the electrochemical workstation and use the electrochemical workstation to conduct a constant potential test. Set the applied potential range to -0.7 V to -2.0 V to obtain the current-time change curve.

[0047] In-situ Raman test:

[0048] After assembly, the reaction gas CO2 is introduced into the gas flow field plate 111, the mixed solution of K2SO4 and H2SO4 with a pH of 2 prepared above is introduced into the cathode flow field plate 112 as the cathode electrolyte, and the mixed solution of K2SO4 and H2SO4 with a pH of 2 prepared above is introduced into the anode flow field plate 113 as the anode electrolyte. Connect the electrochemical workstation and turn on the Raman spectrometer 2, and test the Raman spectra of different positions of the cross-section of the catalyst layer at -0.8V RHE conditions. Define the interface between the carbon paper and the catalyst layer as 0μm, the carbon paper is at -4μm to 0μm, and the catalyst layer is at 0μm to 20μm.

[0049] Among them, the conditions for Raman testing are: using a laser of 638nm, setting each spectral acquisition range to 200 - 2600cm -1 , the laser power is 25%, the spectral acquisition time is 10s, and each spectrum is collected twice for superposition.

[0050] The results of the potentiostatic test in Example 1 are as Figure 4 shown. It can be seen from Figure 4 that the electrochemical reaction cell in the test system can perform normal CO2 / CO electrochemical reduction reactions.

[0051] The in-situ Raman spectra of the cross-section of the gas diffusion electrode tested by the test system of Example 1 are as Figure 5 shown. It can be seen from the figure that at -4μm is the carbon paper, and only the d and g signals of carbon (at ~1300cm -1 and ~1600cm -1 ) can be observed; at 0μm, only the characteristic peaks of cuprous oxide (at ~580cm -1 and ~600cm -1 ) can be observed, indicating that the electrolyte has not penetrated into this area. Starting from 4μm, the cuprous oxide signal disappears, indicating that an electrochemical reaction has occurred. From 4μm to 12μm, bulk CO3 2- (at ~1070cm -1 ) appears, indicating that the microenvironment in this area is alkaline while the bulk is acidic (pH = 2). At the same time, the adsorption peak of the reaction intermediate CO (at ~2100cm -1 ) appears, indicating that this area may be a highly active area. Above 12μm to 20μm, the above two peaks disappear, and only the bulk sulfate signal at ~980cm -1 remains, suggesting that this area may not be a highly active area. Therefore, the in-situ Raman test system for the cross-section of the gas diffusion electrode designed in this application can perform real-time and high-spatial-resolution tests on the cross-section of the catalyst layer on the gas diffusion electrode during the electrochemical reaction process, which is conducive to in-depth understanding of the reaction mechanism.

[0052] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method or article comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method or article.

[0053] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. An in-situ Raman test system for a gas diffusion electrode cross section, comprising a Raman spectrometer and an electrochemical reaction cell; the Raman spectrometer comprises a Raman lens; the electrochemical reaction cell comprises a gas flow field plate, a cathode flow field plate, an anode flow field plate, a liquid leakage prevention plate, a first light window, a second light window, a window sheet, a sealing gasket, a sealing plate, a first fastener, a second fastener, a gas diffusion electrode, an anode, a reference electrode and an ion exchange membrane; The gas flow field plate, gas diffusion electrode, cathode flow field plate, ion exchange membrane, anode flow field plate, anode and liquid leakage prevention plate are arranged in sequence along a first direction and connected and sealed by the first fastener; The Raman lens, the sealing plate, and the sealing gasket are arranged in sequence along a second direction perpendicular to the first direction; The first light window is arranged above the top surfaces of the gas flow field plate and the cathode flow field plate which are perpendicular to the second direction, the first light window cooperates with the sealing gasket, and the window sheet cooperates with the first light window; the second light window is arranged on the sealing plate, and the sealing gasket, the sealing plate, the gas flow field plate and the cathode flow field plate are connected and sealed by a second fastener; The reference electrode is arranged on the cathode flow field plate; The Raman laser emitted by the Raman spectrometer can pass through the second light window and the first light window along the second direction through the Raman lens to reach the cross section of the gas diffusion electrode.

2. The test system according to claim 1, wherein: A first cavity is provided inside the gas flow field plate, a third direction is perpendicular to the first direction and the second direction, a first flow channel communicating with the first cavity is provided on two opposite surfaces of the gas flow field plate perpendicular to the third direction, and a first groove communicating with the first cavity is provided on a first surface of the gas flow field plate perpendicular to the first direction; A second cavity is provided inside the cathode flow field plate, a second flow channel communicating with the second cavity is provided on two opposite surfaces of the cathode flow field plate perpendicular to the third direction, a second groove communicating with the second cavity is provided on the second surface of the cathode flow field plate perpendicular to the first direction, and an internal thread communicating with the second cavity is provided on the opposite surface of the top surface of the cathode flow field plate; A third cavity is provided inside the anode flow field plate, and a third flow channel communicating with the third cavity is provided on two opposite surfaces of the anode flow field plate that are perpendicular to the third direction.

3. The test system according to claim 2, wherein: The gas diffusion electrode is disposed between the first surface and the second surface.

4. The test system according to claim 2, wherein: The reference electrode is disposed in the internal thread.

5. The test system according to claim 2, wherein: The first groove and the second groove are equal in size.

6. The test system according to claim 2, wherein: A first through hole cooperating with the first fastener is provided on the first surface of the gas flow field plate, a second through hole cooperating with the first fastener is provided on the second surface of the cathode flow field plate, a third through hole cooperating with the first fastener is provided on the surface of the anode flow field plate perpendicular to the first direction, and a fourth through hole cooperating with the first fastener is provided on the surface of the liquid leakage prevention plate perpendicular to the first direction.

7. The test system according to claim 1, wherein: A fifth through hole cooperating with the second fastener is provided on the top surface of the gas flow field plate, a sixth through hole cooperating with the second fastener is provided on the top surface of the cathode flow field plate, a seventh through hole cooperating with the second fastener is provided on the sealing plate, and an eighth through hole cooperating with the second fastener is provided on the sealing gasket.

8. The test system according to claim 1, wherein: The Raman lens is movable.

9. The test system according to claim 1, wherein: The window piece is made of any one of quartz and calcium fluoride.

10. Use of the testing system according to any one of claims 1 to 9 for in-situ Raman testing of a gas diffusion electrode cross section.

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