Porous catalyst gas diffusion electrode

Abstract

The utility model provides a porous catalyst gas diffusion electrode, which belongs to the technical field of water electrolysis and comprises an anode diffusion layer serving as a substrate of the electrode; and the porous structure is formed by heterojunction or alloy and is positioned on the anode diffusion layer. According to the utility model, the porous catalyst gas diffusion electrode is prepared by adopting a magnetron sputtering method, and the catalyst is not easy to fall off from the proton exchange membrane, so that the activity of the catalyst is improved, and the activity of the membrane electrode is further improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of water electrolysis, and in particular relates to a porous catalyst gas diffusion electrode. Background Art

[0002] In the electrolysis of water to produce hydrogen, the electrolytic stack is the place where the electrochemical reaction occurs. In the electrolytic stack, the water at the anode is catalytically oxidized on the catalyst surface to generate oxygen and is discharged by the water flow, and the protons pass through the proton exchange membrane to reach the cathode catalyst, where they obtain electrons under the catalytic action of the catalyst to generate hydrogen. Under the same conditions (such as bipolar plates, diffusion layers, proton exchange membranes, etc.), the DC efficiency and service life of the electrolytic stack are mainly subject to the activity and stability of the anode catalyst.

[0003] In existing electrolytic stacks, the cathode catalyst and the anode catalyst are usually coated on both sides of the proton exchange membrane, and then combined with the cathode diffusion layer and the anode diffusion layer to form a "five-in-one" membrane electrode assembly (MEA). During the electrolysis of water, water is oxidized on the anode catalyst layer to generate oxygen, while protons are transferred to the cathode catalyst layer through the proton exchange membrane under the action of the electric field and further reduced to hydrogen. Through the gas diffusion layer, oxygen and hydrogen are respectively exported to the flow channel and then discharged from the electrolytic stack, completing the process of electrolytic hydrogen and oxygen production.

[0004] The existing membrane electrode is to directly apply the cathode and anode catalyst layers on both sides of the proton exchange membrane. In order to ensure the activity of the membrane electrode, a high-load catalyst is often required to be applied on the anode side. In the process of water electrolysis to generate bubbles, the catalyst layer is easily disturbed by the gas and falls off; even under high voltage, the microstructure of the anode catalyst changes, thereby losing its catalytic function and reducing the activity of the membrane electrode. Moreover, with long-term reaction, the proton exchange membrane will gradually degrade from the outside to the inside, and the catalyst will also fall off the proton exchange membrane and lose its catalytic effect, causing the membrane electrode to be more easily deactivated. Utility Model Content

[0005] The utility model provides a porous catalyst gas diffusion electrode, which can solve the problem that in the process of water electrolysis to generate bubbles, the catalyst layer is easily disturbed by gas and falls off; even under high voltage, the microstructure of the anode catalyst changes, thereby losing the catalytic function and reducing the activity of the membrane electrode. Moreover, with a long reaction time, the proton exchange membrane will gradually degrade from the outside to the inside, and the catalyst will also fall off the proton exchange membrane and lose the catalytic effect, resulting in the technical problem that the membrane electrode is more easily deactivated.

[0006] The technical solution provided by the utility model is as follows:

[0007] A porous catalyst gas diffusion electrode is provided, characterized in that the electrode is prepared by any of the methods described, wherein the electrode comprises:

[0008] an anode diffusion layer, serving as a substrate for the electrode;

[0009] The porous structure formed by the heterojunction or alloy is located on the anode diffusion layer.

[0010] In an optional embodiment, the porous structure formed by the heterojunction or alloy includes pores formed by an alloy of the first element and the second element.

[0011] In an optional embodiment, in the pores formed by the alloy of the first element and the second element, the thickness of the first element is greater than the thickness of the second element.

[0012] In an optional embodiment, the first element is metal iridium.

[0013] In an optional embodiment, the second element includes at least one or more of silicon, aluminum, manganese, iron, nickel, and cobalt.

[0014] In an optional embodiment, the molar ratio of the first element to the second element is 1:10-15. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0016] Figure 1 A schematic diagram of the structure of a porous catalyst gas diffusion electrode is shown;

[0017] Figure 2 A schematic diagram of the preparation process of a porous catalyst gas diffusion electrode structure is shown.

[0018] Wherein, the accompanying drawings are marked as follows:

[0019] 1- anode diffusion layer, 2- heterojunction or alloy layer, 3- porous catalyst gas diffusion electrode, 100- porous structure. DETAILED DESCRIPTION

[0020] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0021] As used herein, the term "including" and its variations mean open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "based at least in part on". The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0022] See also Figure 1 , a porous catalyst gas diffusion electrode 3 is also provided, the electrode comprising:

[0023] Anode diffusion layer 1, serving as the base of the electrode;

[0024] The porous structure 100 formed by the heterojunction or alloy is located on the anode diffusion layer 1 .

[0025] The porous catalyst gas diffusion electrode provided in the embodiment of the utility model has at least the following

[0026] Beneficial effects:

[0027] The porous catalyst gas diffusion electrode provided by the embodiment of the utility model can quickly prepare a heterojunction or alloy layer 2 by using a first element and a second element as dual targets, sputtering the dual targets onto the anode diffusion layer 1 by a magnetron sputtering method, and forming a multi-layer heterojunction or alloy layer 2 by alternately sputtering the first target and the second target on the anode diffusion layer 1, and finally performing pore forming treatment on the heterojunction or alloy layer 2 to obtain a porous catalyst gas diffusion electrode 3. Based on the porous catalyst gas diffusion electrode 3 prepared by the magnetron sputtering method of the utility model, the catalyst will not easily fall off from the proton exchange membrane, thereby improving the activity of the catalyst and further improving the activity of the membrane electrode.

[0028] In an optional embodiment, the porous structure 100 formed of a heterojunction or alloy includes pores formed of an alloy of a first element and a second element.

[0029] In the embodiment of the utility model, the heterojunction or alloy layer 2 is subjected to pore-forming treatment, that is, the second element, namely silicon, aluminum, manganese, iron, nickel or cobalt is corroded by acid washing or alkali washing, and the second element combined with the first element is corroded to form a porous structure 100.

[0030] In an optional embodiment, in the pores formed by the alloy of the first element and the second element, the thickness of the first element is greater than the thickness of the second element.

[0031] By setting the thickness of the first element to be greater than the thickness of the second element, after the second element is corroded by an acid solution or an alkaline solution, it is ensured that the second element can form a pore structure. For example, the thickness of the first element can be 1-50 times the thickness of the second element. For example, it can be 10 times, 20 times, 30 times, 40 times, 45 times, 50 times, etc.

[0032] In an optional embodiment, the first element is metal iridium.

[0033] In an optional embodiment, the second element includes at least one or more of silicon, aluminum, manganese, iron, nickel, and cobalt.

[0034] Furthermore, the second element may be silicon, aluminum, manganese, iron, nickel or cobalt, or may be a silicon-aluminum alloy, an alloy of silicon, aluminum and manganese, or an alloy of silicon, aluminum, manganese, iron and nickel, or an alloy of silicon, aluminum, manganese, iron, nickel and cobalt. The embodiments of the utility model are not limited to the metal alloys selected as the second element.

[0035] In an optional embodiment, the molar ratio of the first element to the second element is 1:10-15.

[0036] It should be noted that the size of the pores in the porous catalyst gas diffusion electrode 3 provided in the embodiment of the utility model is determined by the content of the first element and the second element. In this embodiment, the molar ratio of the first element to the second element includes 1:10 to 15. For example, it can be 1:10, 1:11, 1:12, 1:13, 1:14 or 1:15, etc.

[0037] The utility model embodiment provides a porous catalyst gas diffusion electrode which is prepared by the following method.

[0038] S1. Provide an anode diffusion layer 1 as a substrate, and use a first element and a second element as dual targets, wherein the first element is at least one of the Group VIII metals, and the second element is at least one of the transition metals.

[0039] In an optional embodiment, the first element is metal iridium, and the second element includes at least one or more of silicon, aluminum, manganese, iron, nickel, and cobalt.

[0040] Furthermore, the second element may be silicon, aluminum, manganese, iron, nickel or cobalt, or may be a silicon-aluminum alloy, an alloy of silicon, aluminum and manganese, or an alloy of silicon, aluminum, manganese, iron and nickel, or an alloy of silicon, aluminum, manganese, iron, nickel and cobalt. The embodiments of the utility model are not limited to the metal alloys selected as the second element.

[0041] S2. The magnetron sputtering environment pressure is evacuated to a first pressure, and argon gas is introduced and then the pressure is adjusted to a second pressure.

[0042] Before sputtering, the magnetron sputtering environment pressure is first pumped to 0.0004Pa-0.0005Pa, i.e., the first pressure, for example, 0.0004Pa, 0.0042Pa, 0.0045Pa, 0.0047Pa, 0.0049Pa, 0.0005Pa. After the argon gas is introduced, the pressure is adjusted to the second pressure, i.e., 1Pa-3Pa, for example, 1Pa, 1Pa, 1.3Pa, 1.5Pa, 1.6Pa, 1.8Pa, 1.9Pa, 2.1Pa, 2.4Pa, 2.5Pa, 2.6Pa, 2.7Pa, 3Pa.

[0043] In an optional embodiment, the molar ratio of the first element to the second element is 1:10-15.

[0044] It should be noted that the size of the pores in the porous catalyst gas diffusion electrode 3 provided in the embodiment of the utility model is determined by the content of the first element and the second element. In this embodiment, the molar ratio of the first element to the second element includes 1:10 to 15. For example, it can be 1:10, 1:11, 1:12, 1:13, 1:14 or 1:15, etc.

[0045] S3 . Using the first element as a first target material and the second element as a second target material, sputtering is performed alternately on the anode diffusion layer 1 to form a heterojunction or alloy layer 2 .

[0046] In the embodiment of the utility model, the first element is first used as the first target material, that is, metal iridium is first sputtered on the anode diffusion layer 1, and then the second target material, that is, the second element, is sputtered on the metal iridium layer, and the metal iridium and the second element are sputtered repeatedly until the thickness reaches the required thickness and then the sputtering is stopped to form a heterojunction or alloy layer 2. By first sputtering metal iridium and then alternately sputtering the second element to form a multi-layer heterojunction or alloy layer 2, a very good basic structure can be provided for the pore formation of the electrode, and after the pore formation, the metal iridium can be fully exposed, thereby improving the effective utilization rate of the precious metal iridium, and thus improving the activity of the membrane electrode.

[0047] In an optional embodiment, the deposition rate of the first element is 0.015 nm / s to 0.035 nm / s, and the deposition rate of the second element is 0.025 nm / s to 0.035 nm / s.

[0048] It should be noted that the deposition rates of the first element and the second element determine the size of the pores in the porous catalyst gas diffusion electrode 3, that is, the faster the deposition rate of the second element, the thicker the deposited first element and the second element, and the larger the pore structure formed after corrosion.

[0049] As an example, the first element deposition rate may be 0.015 nm / s, 0.016 nm / s, 0.019 nm / s, 0.021 nm / s, 0.023 nm / s, 0.024 nm / s, 0.027 nm / s, 0.028 nm / s, 0.030, 0.032 nm / s, 0.033 nm / s, 0.034 nm / s or 0.035 nm / s, etc. The second metal deposition rate may be 0.025 nm / s, 0.026 nm / s, 0.027 nm / s, 0.028 nm / s, 0.029 nm / s, 0.03 nm / s, 0.31 nm / s, 0.32 nm / s, 0.33 nm / s, 0.34 nm / s or 0.35 nm / s, etc.

[0050] In an optional embodiment, the sputtering time of the first element is 20s-30 / s, and the sputtering time of the second element is 80s-100 / s;

[0051] The number of times of alternate sputtering is 20 to 30 times.

[0052] The sputtering time of the first element can be 20s, 21s, 22s, 23s, 25s, 27s, 28s, 29s, 30 / s. The sputtering time of the second element can be 80s, 81s, 82s, 83s, 85s, 87s, 88s, 89s, 92s, 94s, 95s, 96s, 97s, 98s, 99s or 100 / s.

[0053] The number of times of sputtering is alternately performed is 20 times, 23 times, 24 times, 25 times, 27 times, 28 times, 28 times, and 30 times.

[0054] S4, performing pore forming treatment on the heterojunction or alloy layer 2, and calcining after cleaning, and obtaining the porous catalyst gas diffusion electrode 3 after cooling.

[0055] In an optional embodiment, the heterojunction or alloy layer 2 that has been subjected to pore formation treatment is washed with deionized water, calcined at a preset temperature for 5 to 8 hours, and cooled to obtain a porous catalyst gas diffusion electrode 3 .

[0056] The heterojunction or alloy layer 2 that has been acid-washed or alkaline-washed for pore formation is washed with deionized water to remove the acid or alkaline solution thereon, and calcined at a high temperature of 200° C. to 300° C., for example, calcination can be performed at 200° C., 210° C., 240° C., 260° C., 270° C., 290° C., 300° C., etc. The calcination time can be 5 hours, 6 hours, 7 hours, or 8 hours, etc.

[0057] In an optional embodiment, the heterojunction or alloy layer 2 is subjected to pore-forming treatment, including performing pore-forming treatment in a 3 mol / L to 5 mol / L acid solution or a 3 mol / L to 5 mol / L alkaline solution.

[0058] For example, the concentration of the acid solution may be 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, or 5 mol / L. The concentration of the alkaline solution may be 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, or 5 mol / L.

[0059] In an optional embodiment, the acid solution includes at least one of nitric acid, sulfuric acid or hydrochloric acid. In an optional embodiment, the alkaline solution can be sodium hydroxide.

[0060] It should be noted that the embodiment of the utility model performs pore-forming treatment on the heterojunction or alloy layer 2, that is, by acid washing or alkali washing, the second element, that is, silicon, aluminum, manganese, iron, nickel or cobalt is corroded, and the second element combined with the first element is corroded to form a porous structure 100. The acid solution can be one or a mixture of nitric acid, sulfuric acid or hydrochloric acid. The embodiment of the utility model does not limit the type of the mixture of the acid solution.

[0061] The method and electrode provided by the embodiments of the utility model will be further described below through specific examples.

[0062] Example 1

[0063] The specific process is as follows Figure 2 As shown. The anode diffusion layer 1 is used as the substrate, and metal iridium and metal cobalt are used as dual targets. Before sputtering, the pressure in the vacuum chamber is pumped to 0.0004Pa, high-purity argon gas is introduced, and the pressure in the vacuum chamber is adjusted to 1Pa. With iridium as the target, magnetron sputtering is performed for 20 seconds at a deposition rate of 0.015nm / s; with cobalt as the target, magnetron sputtering is performed for 80 seconds at a deposition rate of 0.025nm / s; the above two steps are repeated 20 times in turn.

[0064] Take out the anode diffusion layer 1 deposited by magnetron sputtering, transfer it into a 3M nitric acid (HNO3) solution, soak it for half an hour, take it out and wash it with deionized water. Put the anode diffusion layer 1 into a nitrogen or vacuum furnace, calcine it at 200°C for five hours, and cool it naturally to obtain a porous catalyst gas diffusion electrode 3 with a porous catalyst layer.

[0065] Example 2

[0066] The anode diffusion layer 1 is used as the substrate, and metal iridium and metal nickel are used as dual targets. Before sputtering, the pressure in the vacuum chamber is pumped to 0.0004Pa, high-purity argon gas is introduced, and the pressure in the vacuum chamber is adjusted to 1Pa. With iridium as the target, magnetron sputtering is performed for 20 seconds at a deposition rate of 0.015nm / s; with nickel as the target, magnetron sputtering is performed for 80 seconds at a deposition rate of 0.025nm / s; the above two steps are repeated 20 times in turn.

[0067] Take out the anode diffusion layer 1 deposited by magnetron sputtering, transfer it into a 3M nitric acid (HNO3) solution, soak it for half an hour, take it out and wash it with deionized water. Put the anode diffusion layer 1 into a nitrogen or vacuum furnace, calcine it at 200°C for five hours, and cool it naturally to obtain a porous catalyst gas diffusion electrode 3 with a porous catalyst layer.

[0068] Example 3

[0069] The anode diffusion layer 1 is used as the substrate, and metal iridium and metal iron are used as dual targets. Before sputtering, the pressure in the vacuum chamber is pumped down to 0.0005Pa, high-purity argon is introduced, and the pressure in the vacuum chamber is adjusted to 1Pa. With iridium as the target, magnetron sputtering is performed for 20 seconds at a deposition rate of 0.015nm / s; with iron as the target, magnetron sputtering is performed for 80 seconds at a deposition rate of 0.025nm / s; the above two steps are repeated 20 times in turn.

[0070] Take out the diffusion layer deposited by magnetron sputtering, transfer it into 3M nitric acid (HNO3) solution, soak it for half an hour, take it out and wash it with deionized water. Put the anode diffusion layer 1 into nitrogen or vacuum furnace, calcine it at 200℃ for five hours, and cool it naturally to obtain a porous catalyst gas diffusion electrode 3 with a porous catalyst layer.

[0071] Example 4

[0072] The anode diffusion layer 1 is used as the substrate, and metal iridium and metal manganese are used as dual targets. Before sputtering, the pressure in the vacuum chamber is pumped to 0.0005Pa, high-purity argon gas is introduced, and the pressure in the vacuum chamber is adjusted to 1Pa. With iridium as the target, magnetron sputtering is performed for 20 seconds at a deposition rate of 0.015nm / s; with manganese as the target, magnetron sputtering is performed for 80 seconds at a deposition rate of 0.025nm / s; the above two steps are repeated 20 times in turn.

[0073] Take out the diffusion layer deposited by magnetron sputtering, transfer it into 3M nitric acid (HNO3) solution, soak it for half an hour, take it out and wash it with deionized water. Put the anode diffusion layer 1 into nitrogen or vacuum furnace, calcine it at 200℃ for five hours, and cool it naturally to obtain a porous catalyst gas diffusion electrode 3 with a porous catalyst layer.

[0074] Example 5

[0075] The anode diffusion layer 1 is used as the substrate, and metal iridium and metal aluminum are used as dual targets. Before sputtering, the pressure in the vacuum chamber is pumped to 0.0004-0.0005Pa, high-purity argon gas is introduced, and the pressure of the vacuum chamber is adjusted to 1Pa. With iridium as the target, magnetron sputtering is performed for 20 seconds at a deposition rate of 0.015nm / s; with aluminum as the target, magnetron sputtering is performed for 80 seconds at a deposition rate of 0.025nm / s; the above two steps are repeated 20 times in turn.

[0076] Take out the diffusion layer deposited by magnetron sputtering, transfer it into 3M sodium hydroxide (NaOH) solution, soak it for half an hour, take it out and wash it with deionized water. Put the anode diffusion layer 1 into nitrogen or vacuum furnace, calcine it at 200℃ for five hours, and cool it naturally to obtain a porous catalyst gas diffusion electrode 3 with a porous catalyst layer.

[0077] Example 6

[0078] The anode diffusion layer 1 is used as the substrate, and the metal iridium and the non-metallic element silicon are used as dual targets. Before sputtering, the pressure in the vacuum chamber is pumped to 0.0005Pa, and high-purity argon gas is introduced to adjust the vacuum chamber pressure to 1Pa. With iridium as the target, magnetron sputtering is performed for 20 seconds at a deposition rate of 0.015nm / s; with silicon as the target, magnetron sputtering is performed for 80 seconds at a deposition rate of 0.025nm / s; the above two steps are repeated 20 times in turn.

[0079] Take out the diffusion layer deposited by magnetron sputtering, transfer it into 3M sodium hydroxide (NaOH) solution, soak it for half an hour, take it out and wash it with deionized water. Put the anode diffusion layer 1 into nitrogen or vacuum furnace, calcine it at 200℃ for five hours, and cool it naturally to obtain a porous catalyst gas diffusion electrode 3 with a porous catalyst layer.

[0080] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A porous catalyst gas diffusion electrode, characterized in that: The electrode comprises: an anode diffusion layer, serving as a substrate for the electrode; A porous structure formed by a heterojunction or an alloy, located on the anode diffusion layer; The porous structure formed by the heterojunction or alloy includes a porous structure formed by an alloy of a first element and a second element; In the pores formed by the alloy of the first element and the second element, the thickness of the first element is greater than the thickness of the second element.

2. The porous catalyst gas diffusion electrode according to claim 1, characterized in that: The first element is metal iridium.

3. The porous catalyst gas diffusion electrode according to claim 2, characterized in that: The second element includes one of silicon, aluminum, manganese, iron, nickel, and cobalt.

4. The porous catalyst gas diffusion electrode according to claim 1, characterized in that: The molar ratio of the first element to the second element is 1:10-15.

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