Self-supporting gas diffusion electrode and preparation method and application thereof

Abstract

The invention provides a self-supporting gas diffusion electrode as well as a preparation method and application thereof. The preparation method comprises the following steps: respectively preparing metal sources to be deposited into precursor solutions for later use; mixing the precursor solution according to the proportion of the metal source of the target catalyst layer to obtain a mixed solution; carrying out ultrasonic cleaning, oil removal and flushing on the cut porous sheet electrode for later use; soaking a porous sheet electrode in the mixed solution, then performing ultrasonic treatment for 1-10 minutes, and soaking for 10-30 minutes; taking out the porous sheet-shaped electrode and absorbing the residual mixed solution on the surface of the porous sheet-shaped electrode; and placing the soaked porous sheet electrode in a UV light environment with a wavelength of 185-254 nm for illumination for 4-48 h to obtain the self-supporting gas diffusion electrode. According to the preparation method disclosed by the invention, no binder is added, and the self-supporting gas diffusion electrode can be industrially prepared on a large scale.

Description

Technical Field

[0001] The invention belongs to the technical field of electrode preparation, and in particular relates to a self-supporting gas diffusion electrode and a preparation method and application thereof. Background Art

[0002] Gas Diffusion Electrode (GDE) is a special porous membrane electrode. Due to its unique porous structure, good conductivity and high catalytic activity, it is widely used in new energy fields such as fuel cells, water electrolysis to produce hydrogen, air batteries, carbon dioxide reduction, nitrogen reduction, etc. The gas diffusion electrode is the core place to realize the electrochemical reaction of energy conversion. The gas phase mass transfer, liquid phase mass transfer and electron transfer at the gas-liquid-solid three-phase interface must be carried out on it. Therefore, its structural design, catalyst selection, preparation process, etc. will directly affect the performance and efficiency of the device.

[0003] As a highly abundant element in the earth's crust, transition metals FeCoNi are not only low-cost, but also have excellent catalytic performance. They can also be comparable to precious metals AuPtRu in the field of alkaline water electrolysis. The traditional method of preparing transition metal catalyst gas diffusion electrodes first synthesizes / purchases the target catalyst nanopowder / particles, and configures the target catalyst into a suitable slurry by adding surfactants, binders, conductive agents, etc., and then modifies the transition metal catalyst onto porous pole pieces such as carbon paper, nickel felt, titanium felt, and stainless steel felt by drop coating, spin coating, spray coating, and transfer printing to prepare gas diffusion electrodes, or modify it onto ion exchange membranes to prepare membrane electrodes for subsequent assembly of energy devices. It can be seen that the catalyst layer and diffusion layer of the gas diffusion electrode prepared by the slurry method are separated, the mass transfer resistance is large, and the adhesion between the two is poor, and long-term use is prone to peeling; therefore, organic dispersants, binders, etc. need to be added during the slurry preparation process, but organic matter will cover the surface active sites of the catalyst, reducing the catalytic performance and efficiency. Self-supporting gas diffusion electrodes do not require the addition of adhesives, reducing factors that may reduce electrochemical performance. At the same time, the higher effective active area can provide more reaction active sites, and have sufficient strength and flexibility to maintain the wide applicability of the electrode. However, the current preparation methods (filtration film formation, freeze drying, in situ growth, etc.) are mostly suitable for laboratory scale and cannot be scaled up to industrial level to stably prepare uniform gas diffusion electrodes. Summary of the invention

[0004] In view of this, the present invention aims to overcome the defects in the prior art and proposes a self-supporting gas diffusion electrode and a preparation method and application thereof.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] In a first aspect, the present invention provides a method for preparing a self-supporting gas diffusion electrode, comprising the following steps:

[0007] S1: preparing the metal sources to be deposited into precursor solutions for standby use;

[0008] S2: mixing the precursor solutions according to the ratio of the metal source of the target catalyst layer to obtain a mixed solution;

[0009] S3: ultrasonically clean, degrease and rinse the cut porous sheet electrode for later use;

[0010] S4: soaking the porous sheet electrode in the mixed solution, then sonicating for 1 to 10 minutes, and soaking for 10 to 30 minutes;

[0011] S5: taking out the porous sheet electrode and absorbing the residual mixed solution on its surface;

[0012] S6: The soaked porous sheet electrode is placed in a UV light environment with a wavelength of 185 nm to 254 nm for 4 to 48 hours to obtain a self-supporting gas diffusion electrode.

[0013] Preferably, the UV light environment in step S6 is a single UV light environment with a wavelength of 185nm to 254nm or a composite UV light environment with two or more wavelengths of 185nm to 254nm.

[0014] Preferably, the metal source in step S1 is a transition metal source or a noble metal source.

[0015] Preferably, the metal source in step S1 is a transition metal source, and the concentration of the precursor solution is 0.1-5 mol / L.

[0016] More preferably, the transition metal source is a transition metal chloride or a transition metal nitrate.

[0017] Further preferably, the transition metal source is one or more of FeCl3, FeCl2, CoCl2, NiCl2, Fe(NO3)3, Fe(NO3)2, Co(NO3)2, and Ni(NO3)2.

[0018] Preferably, the metal source in step S1 is a noble metal source, and the concentration of the precursor solution is 0.1-1 g / 100 mL.

[0019] More preferably, the noble metal source is an organic noble metal compound.

[0020] Further preferably, the noble metal source is one or more of chloroauric acid, platinum acetylacetonate, and ruthenium acetylacetonate.

[0021] Preferably, the porous sheet electrode is titanium felt, nickel felt, stainless steel felt or carbon paper.

[0022] Preferably, the cleaning solution used for ultrasonic cleaning in step S3 is a mixed solution of acetone and anhydrous ethanol in a volume ratio of 1:1.

[0023] Preferably, the solution used for oil removal in step S3 is a hydrochloric acid aqueous solution with a concentration of 1 mol / L.

[0024] In a second aspect, the present invention also includes a self-supporting gas diffusion electrode obtained by the above-mentioned preparation method.

[0025] In a third aspect, the present invention also provides the use of the self-supporting gas diffusion electrode in catalytic oxygen evolution reaction, fuel cell, water electrolysis, carbon dioxide reduction, nitrogen reduction or metal-air battery.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention provides feasibility for preparing a self-supporting gas diffusion electrode through UV irradiation to realize industrial-scale preparation of high-performance self-supporting gas diffusion electrodes through inorganic salt sources: first, the UV irradiation method is simple and easy to operate, the equipment cost is low, and it is easy to industrialize and promote large-scale preparation; second, the precursor has a wide range of applications, and the UV irradiation method can decompose transition metal inorganic / organic salt sources (chlorides, nitrates, organic noble metal compounds, acetyl, etc.), especially inorganic salt sources are widely available and low in cost; third, by adjusting the type and content of the precursor, the type and amount of the deposited catalyst on the electrode can be quickly changed; fourth, a high-performance self-supporting gas diffusion electrode can be directly prepared without using a binder. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a photo of a 1 cm diameter round piece of original titanium felt electrode according to Example 1 of the present invention;

[0029] Figure 2 is a photograph of the titanium felt electrode after being immersed in the FeCoNi metal ion precursor solution according to Example 1 of the present invention;

[0030] Figure 3 This is a photo of the titanium felt electrode loaded with FeCoNi catalyst after UV irradiation in Example 1 of the present invention;

[0031] Figure 4 is a SEM image of the titanium felt electrode after loading FeCoNi according to Example 1 of the present invention;

[0032] Figure 5 : is the element distribution diagram of FeCoNi loaded on the titanium felt electrode prepared in Example 1 of the present invention;

[0033] Figure 6 Element distribution diagrams of titanium felt electrodes prepared in Examples 1 to 3, Comparative Example 5 and Comparative Example 1 of the present invention;

[0034] Figure 7 It is the Raman graph of the titanium felt electrode loaded with single component Co prepared in Example 2 of the present invention and Comparative Example 1;

[0035] Figure 8 This is an XPS graph of FeCoNi loaded on the titanium felt electrode prepared in Examples 1-4 of the present invention;

[0036] Fig. 9 These are electrochemical test diagrams of OER oxygen evolution loaded with single-component, two-component, and three-component titanium felt electrodes prepared in Examples 1, 2, and 5 of the present invention. DETAILED DESCRIPTION

[0037] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0038] The present invention will be described in detail below with reference to the embodiments.

[0039] Example 1

[0040] A method for preparing a self-supporting gas diffusion electrode comprises the following steps:

[0041] (1) Prepare FeCl3, CoCl2, and NiCl2 into 1 mol / L (100 ml each) precursor solutions for later use;

[0042] (2) Pipette 2 ml of FeCl3 solution, 2 ml of CoCl2 solution, and 2 ml of NiCl2 solution into a 10 ml glass beaker and mix well to obtain a mixed solution for later use;

[0043] (3) Punch a 250 μm thick commercial titanium felt into a 1 cm diameter original sheet-shaped original electrode (such as Figure 1 shown);

[0044] (4) ultrasonically clean a 1 cm titanium felt electrode with a mixed solution of acetone and anhydrous ethanol (volume ratio 1:1) for 10 min;

[0045] (5) Soaking the electrode after degreasing with acetone / anhydrous ethanol in 1 mol / L hydrochloric acid for 30 minutes to remove the oxide on its surface;

[0046] (6) Rinse the 1 cm titanium felt electrode soaked in hydrochloric acid with deionized water five times;

[0047] (7) Soak the cleaned titanium felt in 6 ml of the FeCoNi mixed solution prepared in step (2) of step 3, and perform ultrasonic treatment for 5 minutes;

[0048] (8) After standing for 10 minutes, take out the 1 cm round titanium felt electrode and place it on a qualitative filter paper to absorb the metal solution remaining on the surface of the titanium felt electrode (such as Figure 2 shown);

[0049] (9) Place the impregnated 1 cm titanium felt electrode in a UV light box and illuminate it for 24 hours (eg Figure 3 A self-supporting gas diffusion electrode was obtained.

[0050] Example 2

[0051] The method for preparing the self-supporting gas diffusion electrode of this embodiment 2 is different from that of embodiment 1 in that the precursor solution in step (1) is only 1 mol / L CoCl2, and the remaining operating steps are the same as those of embodiment 1 and will not be repeated here.

[0052] Example 3

[0053] The method for preparing the self-supporting gas diffusion electrode of this embodiment 3 is different from that of embodiment 1 in that the precursor solution in step (1) is only 1 mol / L Fe(NO3)3, and the remaining operating steps are the same as those of embodiment 1 and will not be repeated here.

[0054] Example 4

[0055] The method for preparing the self-supporting gas diffusion electrode of this embodiment 4 is different from that of embodiment 1 in that the precursor solution in step (1) is only 1 mol / L NiCl2, and the remaining operating steps are the same as those of embodiment 1 and will not be repeated here.

[0056] Example 5

[0057] The preparation method of the self-supporting gas diffusion electrode of this embodiment 6 is different from that of embodiment 1 in that the precursor solution in step (1) is 1 mol / L NiCl2, 1 mol / L CoCl2, and the remaining operating steps are the same as those of embodiment 1 and will not be repeated here.

[0058] Comparative Example 1

[0059] The method for preparing the self-supporting gas diffusion electrode of this comparative example 1 is different from that of Example 1 in that steps (1), (2) and (7) are omitted, and the remaining steps are the same as those of Example 1 and will not be described again here.

[0060] The 1 cm titanium felt electrodes prepared in Examples 1 to 5 and Comparative Example 1 were characterized by SEM, XRD, and XPS morphology, and then the electrochemical performance of the three-electrode system was tested. Figure 4-Figure 9 As shown, it can be seen that FeCoNi is successfully loaded onto the titanium felt electrode after UV irradiation. After loading FeCoNi, the original three-dimensional mesh porous structure of the titanium felt electrode remains unchanged. In addition, it can be seen that the elements loaded onto the titanium felt electrode by UV irradiation are evenly distributed, and the elements loaded onto the titanium felt electrode are amorphous oxides, and are composed of Fig. 9 It can be seen that the electrochemical performance of the loaded three-component is better than that of the two-component and single-component.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a self-supporting gas diffusion electrode, characterized in that: The steps include: S1: preparing the metal sources to be deposited into precursor solutions for standby use; S2: mixing the precursor solutions according to the ratio of the metal source of the target catalyst layer to obtain a mixed solution; S3: ultrasonically clean, degrease and rinse the cut porous sheet electrode for later use; S4: soaking the porous sheet electrode in the mixed solution, then sonicating for 1 to 10 minutes, and soaking for 10 to 30 minutes; S5: taking out the porous sheet electrode and absorbing the residual mixed solution on its surface; S6: The soaked porous sheet electrode is placed in a UV light environment with a wavelength of 185 nm to 254 nm for 4 to 48 hours to obtain a self-supporting gas diffusion electrode.

2. The method for preparing a self-supporting gas diffusion electrode according to claim 1, characterized in that: The UV light environment in step S6 is a single UV light environment with a wavelength of 185nm to 254nm or a composite UV light environment with two or more wavelengths of 185nm to 254nm.

3. The method for preparing a self-supporting gas diffusion electrode according to claim 1, characterized in that: The metal source in step S1 is a transition metal source or a noble metal source; preferably, the metal source in step S1 is a transition metal source, and the concentration of the precursor solution is 0.1-5 mol / L; preferably, the transition metal source is a transition metal chloride or a transition metal nitrate.

4. The method for preparing a self-supporting gas diffusion electrode according to claim 1, characterized in that: The transition metal source is one or more of FeCl3, FeCl2, CoCl2, NiCl2, Fe(NO3)3, Fe(NO3)2, Co(NO3)2, and Ni(NO3)2.

5. The method for preparing a self-supporting gas diffusion electrode according to claim 1, characterized in that: The metal source in step S1 is a noble metal source, and the concentration of the precursor solution is 0.1-1 g / 100 mL.

6. The method for preparing a self-supporting gas diffusion electrode according to claim 1, characterized in that: The noble metal source is an organic noble metal compound; preferably, the noble metal source is one or more of chloroauric acid, platinum acetylacetonate, and ruthenium acetylacetonate.

7. The method for preparing a self-supporting gas diffusion electrode according to claim 1, characterized in that: The porous sheet electrode is titanium felt, nickel felt, stainless steel felt or carbon paper.

8. The method for preparing a self-supporting gas diffusion electrode according to claim 1, characterized in that: The cleaning solution used for ultrasonic cleaning in step S3 is a mixed solution of acetone and anhydrous ethanol in a volume ratio of 1:1; the solution used for oil removal in step S3 is a hydrochloric acid aqueous solution with a concentration of 1 mol / L.

9. A self-supporting gas diffusion electrode obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the self-supporting gas diffusion electrode according to claim 9 in catalytic oxygen evolution reaction, fuel cell, water electrolysis, carbon dioxide reduction, nitrogen reduction or metal air battery.

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