CN116926585A - Membrane electrode and preparation method and application thereof - Google Patents
Membrane electrode and preparation method and application thereof Download PDFInfo
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- CN116926585A CN116926585A CN202210328358.1A CN202210328358A CN116926585A CN 116926585 A CN116926585 A CN 116926585A CN 202210328358 A CN202210328358 A CN 202210328358A CN 116926585 A CN116926585 A CN 116926585A
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- 239000012528 membrane Substances 0.000 title claims abstract description 103
- 238000002360 preparation method Methods 0.000 title abstract description 18
- 230000003197 catalytic effect Effects 0.000 claims abstract description 119
- 239000003054 catalyst Substances 0.000 claims abstract description 81
- 239000011347 resin Substances 0.000 claims description 42
- 229920005989 resin Polymers 0.000 claims description 42
- 239000002002 slurry Substances 0.000 claims description 39
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 36
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 27
- 230000005588 protonation Effects 0.000 claims description 22
- 238000000034 method Methods 0.000 claims description 20
- 239000011248 coating agent Substances 0.000 claims description 17
- 238000000576 coating method Methods 0.000 claims description 17
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 15
- 238000005406 washing Methods 0.000 claims description 14
- 238000007731 hot pressing Methods 0.000 claims description 12
- 230000008569 process Effects 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 11
- 238000002791 soaking Methods 0.000 claims description 11
- UQSQSQZYBQSBJZ-UHFFFAOYSA-N fluorosulfonic acid Chemical compound OS(F)(=O)=O UQSQSQZYBQSBJZ-UHFFFAOYSA-N 0.000 claims description 9
- 239000003011 anion exchange membrane Substances 0.000 claims description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 5
- 238000004140 cleaning Methods 0.000 claims description 4
- 238000010023 transfer printing Methods 0.000 claims description 4
- 238000009210 therapy by ultrasound Methods 0.000 claims description 3
- 238000012546 transfer Methods 0.000 abstract description 10
- 229910000510 noble metal Inorganic materials 0.000 abstract description 9
- 239000007788 liquid Substances 0.000 abstract description 6
- 238000005868 electrolysis reaction Methods 0.000 description 14
- 238000011068 loading method Methods 0.000 description 11
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 10
- 229910052739 hydrogen Inorganic materials 0.000 description 8
- 239000001257 hydrogen Substances 0.000 description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 7
- 239000000306 component Substances 0.000 description 7
- 239000011148 porous material Substances 0.000 description 6
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000008367 deionised water Substances 0.000 description 3
- 229910021641 deionized water Inorganic materials 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000002086 nanomaterial Substances 0.000 description 3
- 150000003460 sulfonic acids Chemical class 0.000 description 3
- DSVGQVZAZSZEEX-UHFFFAOYSA-N [C].[Pt] Chemical compound [C].[Pt] DSVGQVZAZSZEEX-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000001132 ultrasonic dispersion Methods 0.000 description 2
- DKGAVHZHDRPRBM-UHFFFAOYSA-N Tert-Butanol Chemical compound CC(C)(C)O DKGAVHZHDRPRBM-UHFFFAOYSA-N 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- -1 hydrogen ions Chemical class 0.000 description 1
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 1
- 239000010416 ion conductor Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229920000867 polyelectrolyte Polymers 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000000707 stereoselective effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
- C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
- C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
- C25B9/23—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms comprising ion-exchange membranes in or on which electrode material is embedded
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
- C25B1/02—Hydrogen or oxygen
- C25B1/04—Hydrogen or oxygen by electrolysis of water
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Electrodes For Compound Or Non-Metal Manufacture (AREA)
Abstract
The invention provides a membrane electrode, a preparation method and application thereof, wherein the membrane electrode comprises: a proton exchange membrane and a first catalytic layer positioned on at least one side of the proton exchange membrane; the microstructure of the first catalytic layer comprises a plurality of nano units which are orderly arranged, so that the first catalytic layer is in an orderly nano array, wherein the nano unit components are in gradient arrangement. The gradient ordered nano-array first catalytic layer effectively solves the problems of hindered gas-liquid mass transfer, low noble metal catalyst utilization rate, large interfacial resistance between the membrane and the catalytic layer and poor interfacial stability of the traditional unordered structure catalytic layer; according to the invention, the first catalytic layer with the AAO template is hot-pressed with the proton exchange membrane, and then the membrane electrode obtained by separating the template ensures that the nano array structure in the catalytic layer is not collapsed, and the nano array structure is vertically distributed on the surface of the proton exchange membrane, so that the problem that the structure is easy to collapse when the traditional porous catalytic layer and the proton exchange membrane are hot-pressed is effectively solved.
Description
Technical Field
The invention relates to the field of hydrogen production by water electrolysis, in particular to a membrane electrode and a preparation method and application thereof.
Background
The proton exchange membrane electrolyzed water (Proton Exchange Membrane Water Electrolysis, PEMWE) hydrogen production has the advantages of high energy conversion efficiency, high hydrogen purity, high response speed and the like, but the catalytic layer of the proton exchange membrane electrolyzed water (PEMWE) hydrogen production needs noble metal as a catalyst, so that the commercial application is severely limited. The catalyst of the disordered structure catalytic layer prepared by the traditional spraying method has low utilization rate, so that high loading (2-3 mg cm) -2 ) To meet performance requirements (Journal of Materials Chemistry A,2015,5,4775-4778). Reducing the amount of noble metal catalyst in the membrane electrode is an urgent need for large-scale application of PEMWE. At present, in addition to the development of alternative high-activity non-noble metal catalysts, many researches focus on developing high-performance membrane electrodes with high-efficiency active site expression from the view point of membrane electrode structural design.
The membrane electrode (Membrane Electrode Assemblies, MEA) is the core component of PEMWE, and an ideal structure of the membrane electrode needs to have maximized three-phase reaction interface and high-speed mass transfer. The nano ordered structure can effectively expand the three-phase reaction interface to obtain the ultra-low catalyst loading (20-86 mug cm) -2 ) High performance MEA (1.3-1.7A cm) -2 @1.7v) (Nano Energy,2019,58,158-166; journal of Power Sources,2017,342,947-955; nat Commun 2020,11,4921). Although this method can reduce the catalyst loading to 1/100-1/25 of the original catalyst loading, the MEA stability is poor. Compared with proton exchange membrane fuel cells, PEMWE needs to further enhance the interfacial binding force and interfacial compatibility between the catalyst particles, the stereospecific resin, and the proton exchange membrane to prevent the catalyst layer from binding due to water and the generated gas washoutStructural damage affects lifetime. In the field of fuel cells, the ordered nano array catalytic layer and the gradient catalytic layer have respectively been proved to be capable of effectively improving the interface bonding strength among the catalyst, the resin and the membrane, so that the catalyst can be applied to PEMWE, but the preparation difficulty of the catalytic layer with both the gradient structure and the ordering structure is high, no report is made at present, and the ordered nano structure is extremely easy to collapse in the MEA preparation process, particularly in the hot pressing process.
In view of the above, it is necessary to provide an MEA, and a preparation method and application thereof, so as to avoid the problems of the prior art that the gas-liquid mass transfer of the catalytic layer with a conventional disordered structure is hindered, the utilization rate of the noble metal catalyst is low, the interfacial resistance between the membrane and the catalytic layer is large, the interfacial stability is poor, and the MEA with two structures of gradient ordering is difficult to prepare and the nano structure is easy to collapse.
Disclosure of Invention
In view of the shortcomings of the prior art, the invention aims to provide an MEA, a preparation method and application thereof, which are used for solving the problems that in the prior art, gas-liquid mass transfer of a catalytic layer with a traditional disordered structure is blocked, the utilization rate of a noble metal catalyst is low, interface resistance between a membrane and the catalytic layer is large, interface stability is poor, and the MEA with two structures of gradient ordering is difficult to prepare and a nano structure is easy to collapse.
To achieve the above and other related objects, the present invention provides an MEA comprising:
a proton exchange membrane and a first catalytic layer positioned on at least one side of the proton exchange membrane;
the first catalytic layer comprises a catalyst and a stereogenic resin; the microstructure of the first catalytic layer comprises a plurality of nano units which are orderly arranged, so that the first catalytic layer is in an ordered nano array, wherein the nano units are arranged in a gradient manner in the forming process to form a gradient structure, the catalyst content is gradually reduced from the surface of the nano units to the inside, and the three-dimensional resin content is gradually increased from the surface of the nano units to the inside.
Optionally, both sides of the proton exchange membrane are provided as the first catalytic layer.
Optionally, the shape of the nano-unit is cylindrical or conical.
Optionally, the thickness of the nano unit ranges from 200nm to 3 μm, the maximum cross section size of the nano unit ranges from 10nm to 1 μm, and the distance between two adjacent nano units ranges from 100nm to 1 μm. .
The invention provides a preparation method of an MEA, which is used for preparing the MEA, and comprises the following steps:
s1: providing an AAO template with nano micropores and catalyst slurry, wherein the catalyst slurry comprises a catalyst and a stereogenic resin;
s2: coating the catalyst slurry on the surface of the AAO template to form a first catalytic layer, wherein the microstructure of the first catalytic layer comprises a plurality of orderly arranged nano units so as to enable the first catalytic layer to be in an orderly nano array, wherein the nano units are arranged in a gradient manner in the forming process to form a gradient structure, the catalyst content is gradually reduced from the surface of the nano units to the inside, and the three-dimensional resin content is gradually increased from the surface of the nano units to the inside;
s3: placing the first catalytic layer with the AAO template in a vacuum oven for negative pressure treatment;
s4: carrying out transfer printing treatment on the first catalytic layer with the AAO template and the proton exchange membrane by hot pressing;
s5: and (3) carrying out alkaline cleaning treatment and protonation treatment on the structure to obtain the MEA with the graded and ordered first catalytic layer.
Optionally, the components of the catalyst slurry in step S1 include the catalyst, a stereogenic resin, water and alcohol, wherein the stereogenic resin forms the catalyst slurry in a solution form, the stereogenic resin solution is a perfluorosulfonic acid resin solution, and the mass ratio of the catalyst, the stereogenic resin solution, the water and the alcohol is 1: (1-10): (1-50): (1-50); the specific steps for preparing the catalyst slurry include: mixing the catalyst, the three-dimensional resin solution, water and alcohol, and carrying out ultrasonic treatment for 0.1-4 h.
Optionally, in step S2, the processing manner of the gradient structure is layer-by-layer coating or horizontal standing processing; when the layer-by-layer coating mode is adopted, the concrete steps comprise coating the catalyst slurry with different stereo resin contents on the surface of the AAO template layer by layer from low to high in stereo resin content for 2-8 times; when the horizontal standing treatment mode is adopted, the time range of the horizontal standing treatment is 0-10 h, the temperature range is 0-50 ℃, and the time range does not comprise the endpoint value.
Optionally, the negative pressure treatment condition in step S3 is: the temperature range is 0-50 ℃, the negative pressure range is-0.1-0 MPa, and the time range is 0-50 h, wherein the time range does not comprise the endpoint value.
Optionally, the hot pressing and transferring conditions in step S4 are as follows: the temperature range is 60-200 ℃, the pressure range is 5-60 MPa, and the time range is 3 min-20 h.
Optionally, the specific steps of step S5 are: soaking the MEA with the AAO template in a sodium hydroxide solution for alkaline washing, wherein the alkaline washing condition is 0.1-10M NaOH soaking, the alkaline washing time is 5-60 h, and the alkaline washing temperature is 10-60 ℃; soaking the MEA washed with the AAO template in dilute sulfuric acid for protonation under the condition of 0.1-2M H 2 SO 4 Soaking, wherein the protonation time ranges from 12h to 60h, and the protonation temperature ranges from 10 ℃ to 60 ℃.
The invention also provides an application of the MEA to water electrolysis of a proton exchange membrane or water electrolysis of an anion exchange membrane.
As described above, the MEA of the present invention has the following advantageous effects: 1. the invention obtains the first catalytic layer with stable microcosmic appearance and good uniformity by controlling the appearance, the gradient condition and the negative pressure condition of the AAO template, and particularly, the microstructure comprises a plurality of orderly arranged nano units so that the first catalytic layer is in an orderly nano array, wherein the nano units are arranged in a gradient way in the forming process to form a gradient structure, and the problems of blocked gas-liquid mass transfer, low utilization rate of noble metal catalysts, large interfacial resistance between a film and the catalytic layer and poor interfacial stability of the traditional unordered catalytic layer are effectively solved; 2. according to the invention, the first catalytic layer with the AAO template is hot-pressed and transferred with the proton exchange membrane, and the MEA obtained by separating the templates ensures that the nano array structure in the catalytic layer is not collapsed, and the nano array structure is vertically distributed on the surface of the proton exchange membrane, so that the problem that the structure is easy to collapse when the traditional porous catalytic layer and the proton exchange membrane are hot-pressed is effectively solved; 3. the invention lays a foundation for low-cost, high-efficiency and stable operation of PEMWE hydrogen production.
Drawings
Fig. 1 is a schematic view showing the overall structure of the MEA of the present invention.
Fig. 2 shows a schematic flow chart of a method for preparing an MEA according to the present invention.
Fig. 3 to 7 show schematic structural views showing respective steps of the MEA manufacturing method of the present invention.
Fig. 8 is a graph showing the polarization curves of conventional MEA with the same catalyst loading for example 1 and example 2 of the present invention.
FIG. 9 is a scanning electron microscope image of the morphology of the catalytic layer according to example 2 of the present invention.
Fig. 10 shows a surface view of Ir elements in the catalytic layer of example 2 of the present invention.
Figure 11 is a graph showing the CV curve comparison of example 2 of the present invention with a conventional MEA of the same catalyst loading.
Fig. 12 is a graph showing the stability of example 2 of the present invention compared to a conventional MEA with the same catalyst loading.
Description of element reference numerals
10 AAO template
11. Nanometer micropore
20. Catalyst slurry
21. First catalytic layer
22. Second catalytic layer
30. Proton exchange membrane
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
Please refer to fig. 1 to 12. It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings rather than the number, shape and size of the components in actual implementation, and the form, number and proportion of each component in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.
As shown in fig. 1, the present invention provides an MEA, including a proton exchange membrane 30, and a first catalytic layer 21 located on at least one side of the proton exchange membrane 30;
the first catalytic layer 21 includes a catalyst and a stereogenic resin; the microstructure of the first catalytic layer 21 includes a plurality of nano units in ordered arrangement, so that the first catalytic layer presents an ordered nano array, wherein the nano units are arranged in a gradient manner in a forming process to form a gradient structure, the catalyst content gradually decreases from the surface of the nano units to the inside, and the three-dimensional resin content gradually increases from the surface of the nano units to the inside.
As an example, one side of the proton exchange membrane 30 is provided as the first catalytic layer 21, and the other side is provided as the second catalytic layer 22 (as shown in fig. 1) of a conventional disordered structure; as a preferred example, both sides of the proton exchange membrane 30 are provided as the first catalytic layer 21. The first catalytic layer 21 of the ordered nano-array can effectively solve the problems of hindered gas-liquid mass transfer, low utilization rate of noble metal catalyst, large interfacial resistance between the membrane and the catalytic layer and poor interfacial stability of the traditional catalytic layer with a disordered structure.
The catalyst is Ir and IrO 2 Pt, pt/C and RuO 2 One or a combination of more than two of the above, wherein Pt/C is platinum carbon.
The catalyst will be concentrated at the surface of the nano-units, which in one example are cylindrical in shape, including cylindrical and prismatic; in another preferred example the shape of the nano-units is a cone, including conical and pyramidal, where the largest cross-section of the nano-units is connected to the proton exchange membrane 30; the tapered nano-units perform better than the cylindrical nano-units.
As an example, the nano-unit thickness ranges from 200nm to 3 μm; the maximum cross-sectional dimension of the nano-unit ranges from 10nm to 1 mu m, when the nano-unit is cylindrical in shape, the maximum cross-sectional dimension is the diameter of a horizontal cross-section circle, when the nano-unit is prismatic in shape, the maximum cross-sectional dimension is the maximum diagonal dimension of the horizontal cross-section, when the nano-unit is conical in shape, the maximum cross-sectional dimension is the diameter of the horizontal cross-section circle, and when the nano-unit is prismatic in shape, the maximum cross-sectional dimension is the maximum diagonal dimension of the horizontal cross-section; the distance between two adjacent nanometer units is 100 nm-1 μm.
It should be noted that, in the same MEA, the shape, size, and spacing of the nano-units must be kept uniform, so as to avoid the non-uniform structure of the nano-array, which causes collapse when the nano-array is thermally press-bonded to the proton exchange membrane 30.
As shown in fig. 2 to 7, the present invention provides a method for manufacturing an MEA, which can be used to manufacture the MEA described above, and the method for manufacturing the MEA described above will be described in detail below with reference to the accompanying drawings.
As shown in fig. 2 and 3, step S1 is first performed to provide an AAO template 10 with nano-micropores 11 and a catalyst slurry 20, wherein the catalyst slurry 20 includes a catalyst and a stereogenic resin. The AAO template 10 is an anodic aluminum oxide template, the nano micropores 11 of the AAO template 10 are cylindrical or conical, wherein the cylindrical shape comprises a cylindrical shape and a prismatic shape, the conical shape comprises a conical shape and a prismatic shape, the specific shape can be selected according to actual needs, the conical shape is preferably adopted in the invention, and the MEA performance of the conical structure can be obviously better than that of the MEA of the cylindrical structure.
In step S1, the components of the catalyst slurry 20 include the catalyst, a stereogenic resin, water and alcohol, wherein the stereogenic resin forms the catalyst slurry 20 in the form of a solution, the stereogenic resin solution is a perfluorosulfonic acid resin solution, and the mass ratio of the catalyst, the stereogenic resin solution, the water and the alcohol is 1: (1-10): (1-50): (1-50); the specific steps for preparing the catalyst slurry 20 include: mixing the catalyst, the three-dimensional resin solution, water and alcohol, and carrying out ultrasonic treatment for 0.1-4 h. It should be noted here that the mass ratio of the components of the catalyst slurry 20 may be set according to actual needs, as long as it is within this range; the stereogenic resin is a solid polyelectrolyte, also known as a hydrogen ion conductor, capable of conducting hydrogen ions in the catalyst slurry 20.
As an example, the catalyst is Ir, irO 2 Pt, pt/C and RuO 2 One or a combination of more than two of the above, wherein Pt/C is platinum carbon.
As shown in fig. 2 and fig. 4, step S2 is performed, the surface of the AAO template 10 is coated with the catalyst slurry 20 to form a first catalytic layer 21, and the microstructure of the first catalytic layer 21 includes a plurality of nano units in ordered arrangement, so that the first catalytic layer 21 is in an ordered nano array, wherein the nano units are in gradient arrangement in the formation process to form a gradient structure, the catalyst content gradually decreases from the surface to the inside of the nano units, and the three-dimensional resin content gradually increases from the surface to the inside of the nano units.
As an example, the treatment mode of the gradient structure is layer-by-layer coating or horizontal standing treatment.
When the gradient treatment is layer-by-layer coating, the specific steps include that the catalyst slurry 20 with different stereo resin contents is coated on the surface of the AAO template 10 layer by layer from low to high in the stereo resin content for 2 to 8 times, and the number of layer-by-layer coating times can be set according to actual needs as long as the number is within the range.
When the gradient treatment is horizontal standing treatment, the catalyst slurry 20 is coated on the surface of the AAO template 10 at one time, and the time range of the horizontal standing treatment is 0-10 h, the temperature range is 0-50 ℃, wherein the time range does not comprise an endpoint value; the catalyst is heavier, the stereotactic resin is lighter, the purpose of the horizontal standing treatment is to precipitate the catalyst on the surface of the nano unit, the stereotactic resin floats on the middle and upper parts, and in the subsequent process, the stereotactic resin can be better contacted with the proton exchange membrane 30; furthermore, the tapered nano-units may have more exposed area than the catalyst of the cylindrical nano-units. The longer the horizontal standing treatment is, the more favorable the formation of gradient, but the longer the standing time is, the solvent volatilizes, the catalyst slurry 20 is solidified in advance, and the subsequent negative pressure treatment cannot completely fill the catalyst slurry 20 into the nano micropores 11 of the AAO template 10; the time and temperature of the horizontal standing treatment may be in accordance with the actual need, as long as they are within this range.
The gradient of the horizontal standing treatment is more obvious than the gradient of the layer-by-layer coating, the transition is natural, the gradient of the layer-by-layer coating is limited by the number of batch coating, and the specific gradient treatment can be selected according to actual needs.
As shown in fig. 2 and 5, next, step S3 is performed, in which the first catalytic layer 21 with the AAO template 10 is placed in a vacuum oven, and negative pressure treatment is performed.
As an example, the negative pressure treatment conditions are: the temperature range is 0-50 ℃, the negative pressure range is-0.1-0 MPa, and the time range is 0-50 h, wherein the time range does not comprise an endpoint value; the specific conditions of the negative pressure treatment can be set according to actual needs, so long as the conditions are within the range.
As shown in fig. 2 and 6, next, step S4 is performed to heat-press the first catalytic layer 21 with the AAO template 10 and the proton exchange membrane 30, and transfer the first catalytic layer. In the present invention, the proton exchange membrane 30 is preferably a perfluorosulfonic acid membrane because of its superior performance.
As an example, the hot press, transfer process conditions are: the temperature range is 60-200 ℃, the pressure range is 5-60 MPa, and the time range is 3 min-20 h; the specific conditions of the hot press treatment can be set according to actual needs, so long as the conditions are within the range.
As an example, in the preparation of the MEA in which the first catalytic layer 21 is disposed on one side of the proton exchange membrane 30 and the second catalytic layer 22 is disposed on the other side of the proton exchange membrane 30, before the first catalytic layer 21 with the AAO template 10 is hot pressed with the proton exchange membrane 30, the second catalyst 22 with a disordered structure is prepared on the other side of the proton exchange membrane 30 by a conventional spraying method, and then hot pressing and transfer printing are performed; as a preferred example, in the preparation of the MEA in which the first catalytic layer 21 is provided on both sides of the proton exchange membrane 30, two first catalytic layers 21 with the AAO template 10 are simultaneously hot-pressed with both sides of the proton exchange membrane 30, and a transfer process is performed.
As shown in fig. 2 and 7, next, step S5 is performed to perform an alkaline cleaning treatment and a protonation treatment on the above-described structure, thereby obtaining the MEA having the graded and ordered first catalytic layer 21.
Step S5 is carried out by soaking the membrane electrode with the AAO template 10 in sodium hydroxide solution for alkaline washing, washing the AAO template 10, wherein the alkaline washing condition is that 0.1-10M NaOH is used for soaking, the alkaline washing time is 5-60 h, and the alkaline washing temperature is 10-60 ℃; then the membrane electrode washed with the AAO template 10 is soaked in dilute sulfuric acid for protonation, wherein the protonation condition is 0.1-2M H 2 SO 4 Soaking, wherein the protonation time ranges from 12h to 60h, and the protonation temperature ranges from 10 ℃ to 60 ℃. The specific conditions of the alkaline cleaning treatment can be set according to actual needs and are only in the range; the protons areThe specific conditions of the chemical treatment may be set according to actual needs as long as they are within this range. The first catalytic layer 21 with the AAO template 10 and the proton exchange membrane 30 are hot-pressed, and then the membrane electrode obtained by washing away the AAO template 10 ensures that the nano array structure in the first catalytic layer 21 is not collapsed, and the nano array structure is vertically distributed on the surface of the proton exchange membrane 30, so that the problem that the structure is easy to collapse when the traditional porous catalytic layer and the proton exchange membrane are hot-pressed is effectively solved.
Example 1
In this embodiment, the shape of the nano-micropores 11 of the AAO template 10 is a cylindrical pore structure, the diameter of the largest cross section of the cylindrical AAO template is 500nm, the distance between two adjacent cylindrical pores is 600nm, and the depth is 400nm. In the preparation work of preparing the MEA, the AAO template 10 is ultrasonically cleaned in ethanol solution for 2min, then ultrasonically cleaned by deionized water for 2min, and dried for later use.
The specific preparation method of this example is as follows: first 8mg RuO 2 48mg of perfluorosulfonic acid solution, 150mg of water and 100mg of isopropanol solution are mixed and dispersed for 1 hour by ultrasonic to obtain a catalyst layer slurry 20; taking 50mg of the catalytic layer slurry 20, coating the catalytic layer slurry on the surface of the AAO template 10 at one time, and horizontally standing at 30 ℃ for 2 hours; then putting the mixture into a vacuum oven, and carrying out negative pressure treatment for 24 hours at the temperature of 30 ℃ and the pressure of-0.1M Pa to obtain the first catalytic layer 21.
And then hot-pressing the first catalytic layer 21 with the AAO template 10 and the perfluorinated sulfonic acid membrane, wherein the hot-pressing condition is that the temperature is 130 ℃, the pressure is 20MPa, and the time is 20h. Then the membrane electrode with the AAO template 10 is soaked in 2M NaOH solution at 40 ℃ for 20 hours, the AAO template 10 is washed off, and finally the membrane electrode is soaked in 1M H 2 SO 4 And (3) medium protonation, wherein the protonation time is 48h, and the protonation temperature is 25 ℃.
Example 2
In this embodiment, the shape of the nano-micropores 11 of the AAO template 10 is a structure with a conical pore canal, the diameter of the largest cross section of the conical AAO template is 450nm, the distance between two adjacent cylindrical pores is 450nm, and the depth is 500nm. In the preparation work of preparing the MEA, the AAO template 10 is ultrasonically cleaned in ethanol solution for 2min, then ultrasonically cleaned by deionized water for 2min, and dried for later use.
The specific preparation method of this example is as follows: firstly, mixing 8mg of Ir,40mg of perfluorosulfonic acid solution, 130mg of water and 130mg of tertiary butanol solution, and performing ultrasonic dispersion for 0.5h to obtain catalytic layer slurry 20; taking 30mg of the catalytic layer slurry 20, coating the catalytic layer slurry on the surface of the AAO template 10 at one time, and horizontally standing for 1h at 20 ℃; then put into a vacuum oven and subjected to negative pressure treatment for 6 hours at 25 ℃ and-0.1M Pa, thereby obtaining the first catalytic layer 21.
And then hot-pressing the first catalytic layer 21 with the AAO template 10 and the perfluorinated sulfonic acid membrane, wherein the hot-pressing condition is that the temperature is 140 ℃, the pressure is 20MPa, and the time is 8 hours. Then the membrane electrode with the AAO template 10 is soaked in a 1M NaOH solution at 25 ℃ for 12 hours, the AAO template 10 is washed off, and finally the membrane electrode is soaked in 1M H 2 SO 4 And (3) medium protonation, wherein the protonation time is 24h, and the protonation temperature is 25 ℃.
As shown in FIG. 8, the MEAs of example 1 and example 2 were compared with a conventional MEA of the same catalyst loading of 0.2mg cm -2 The polarization curve was measured at 80 c, and it can be seen from the graph that the electrolyte performance of the MEA (examples 1 and 2) having the graded, ordered first catalytic layer 21 is superior to that of the conventional MEA. While the conical nanoarray MEA (example 2) had a current density of 2A cm -2 The voltage was only 1.80V, which was lower than that of the cylindrical nano-array MEA (example 1) at 2A cm -2 The voltage at (1.87V) indicated that the conical nanoarray MEA performed better than the cylindrical nanoarray MEA.
Further characterizing the conical nano-array first catalytic layer 21 of example 2, its scanning electron microscope and Ir element scanning are shown in fig. 9 to 10; as can be seen from fig. 9, the first catalytic layer 21 of example 2 has an inverted cone shape, and the size conforms to the AAO template; as can be seen from fig. 10, the Ir element exhibits a concentration decreasing distribution from the conical surface to the inside. Fig. 9 and 10 illustrate that example 2 is an MEA having a graded, ordered first catalytic layer 21.
As shown in fig. 11, the MEA of example 2 was compared with a conventional MEA of the same catalyst loading, wherein the catalyst loading was 0.2mg cm -2 The test temperature is 60 ℃, and the measured anode CV curve shows that the integral area of hydrogen desorption in the embodiment 2 is obviously larger than that of the traditional catalytic layer, which shows that the gradient and conical structure can obviously improve the electrochemical reaction active area of the catalytic layer, thereby improving the utilization rate of the catalyst.
As shown in fig. 12, the MEA of example 2 was compared in stability with a conventional MEA of the same catalyst loading, in which the test current density was 1A cm -2 The temperature is 80 ℃, and the stability of the example 2 is obviously better than that of the traditional MEA, which shows that the gradient and conical structure can obviously improve the interface stability.
Example 3
In this embodiment, the shape of the nano-micropores 11 of the AAO template 10 is a structure with a conical pore channel, the diameter of the largest cross section of the conical AAO template is 500nm, the distance between two adjacent cylindrical pores is 500nm, and the depth is 2500nm. In the preparation work of preparing the MEA, the AAO template 10 is ultrasonically cleaned in ethanol solution for 2min, then ultrasonically cleaned by deionized water for 2min, and dried for later use.
The specific preparation method of this example is as follows: 8mg of IrO was added 2 32mg of perfluorosulfonic acid solution, 100mg of water and 200mg of isopropyl alcohol solution were mixed (designated as catalytic layer slurry No. 1); 8mg IrO 2 50mg of perfluorosulfonic acid solution, 100mg of water and 200mg of isopropyl alcohol solution were mixed (designated as catalytic layer slurry No. 2); 8mg IrO 2 Mixing 60mg of perfluorosulfonic acid solution, 100mg of water and 200mg of isopropanol solution (marked as catalytic layer slurry No. 3), respectively performing ultrasonic dispersion on the three catalytic layer slurries 20 for 1 hour, taking 60mg of three catalytic layer slurries 20 respectively, and sequentially coating the catalytic layer slurries No. 1 to No. 3 on the surface of the AAO template 10; then placing the mixture into a vacuum oven, and carrying out negative pressure treatment for 24 hours at 20 ℃ and minus 0.05MPa to obtain the first catalytic layer 21.
And then hot-pressing the first catalytic layer 21 with the AAO template 10 and the perfluorinated sulfonic acid membrane, wherein the hot-pressing condition is that the temperature is 150 ℃, the pressure is 30MPa, and the time is 8 hours. Thereafter the tape is takenThe MEA with the AAO template 10 was immersed in a 0.5M NaOH solution at 30℃for 24 hours, the AAO template 10 was washed off, and finally the MEA was immersed in 0.5. 0.5M H 2 SO 4 And (3) medium protonation, wherein the protonation time is 60h, and the protonation temperature is 25 ℃.
The invention also provides an application of the MEA to water electrolysis of a proton exchange membrane or water electrolysis of an anion exchange membrane.
The MEA with the graded and ordered first catalytic layer 21 is applied to the water for proton exchange membrane electrolysis or the water for anion exchange membrane electrolysis, the first catalytic layer 21 of the MEA can be used as an anode or a cathode in the water for proton exchange membrane electrolysis or can be used as an anode or a cathode in the water for anion exchange membrane electrolysis, and the catalytic layer on the other side of the proton exchange membrane 30 can be the first catalytic layer 21 or the second catalytic layer 22; when the first catalytic layer 21 on one side of the proton exchange membrane 30 is an anode in the water of proton exchange membrane electrolysis or the water of anion exchange membrane electrolysis, the first catalytic layer 21 or the second catalytic layer 22 on the other side of the proton exchange membrane 30 is a cathode, and similarly, when the first catalytic layer 21 on one side of the proton exchange membrane 30 is a cathode in the water of proton exchange membrane electrolysis or the water of anion exchange membrane electrolysis, the first catalytic layer 21 or the second catalytic layer 22 on the other side of the proton exchange membrane 30 is an anode.
In summary, the present invention provides a membrane electrode, and a preparation method and application thereof, where the membrane electrode includes: a proton exchange membrane and a first catalytic layer positioned on at least one side of the proton exchange membrane; the microstructure of the first catalytic layer comprises a plurality of nano units which are orderly arranged, so that the first catalytic layer is in an ordered nano array, wherein the nano units are arranged in a gradient manner in the forming process, and a gradient structure is formed. The ordered nano-array first catalytic layer effectively solves the problems of the traditional unordered structure catalytic layer that gas-liquid mass transfer is hindered, the utilization rate of noble metal catalyst is low, the interface resistance between the membrane and the catalytic layer is large, and the interface stability is poor; according to the invention, the first catalytic layer with the AAO template is hot-pressed and transferred with the proton exchange membrane, and the membrane electrode obtained by separating the template ensures that the nano array structure in the first catalytic layer is not collapsed, and the nano array structure is vertically distributed on the surface of the proton exchange membrane, so that the problem that the structure is easy to collapse when the traditional porous catalytic layer and the proton exchange membrane are hot-pressed is effectively solved; the invention lays a foundation for low-cost, high-efficiency and stable operation of PEMWE hydrogen production. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (11)
1. A membrane electrode, characterized in that the membrane electrode comprises:
a proton exchange membrane and a first catalytic layer positioned on at least one side of the proton exchange membrane;
the first catalytic layer comprises a catalyst and a stereogenic resin; the microstructure of the first catalytic layer comprises a plurality of nano units which are orderly arranged, so that the first catalytic layer is in an ordered nano array, wherein the nano units are arranged in a gradient manner in the forming process to form a gradient structure, the catalyst content is gradually reduced from the surface of the nano units to the inside, and the three-dimensional resin content is gradually increased from the surface of the nano units to the inside.
2. The membrane electrode according to claim 1, wherein: both sides of the proton exchange membrane are provided with the first catalytic layer.
3. The membrane electrode according to claim 1, wherein: the nano-units are cylindrical or conical in shape.
4. The membrane electrode according to claim 1, wherein: the thickness of the nanometer unit ranges from 200nm to 3 mu m, the maximum cross section size of the nanometer unit ranges from 10nm to 1 mu m, and the distance between two adjacent nanometer units ranges from 100nm to 1 mu m.
5. A method for preparing a membrane electrode, comprising:
s1: providing an AAO template with nano micropores and catalyst slurry, wherein the catalyst slurry comprises a catalyst and a stereogenic resin;
s2: coating the catalyst slurry on the surface of the AAO template to form a first catalytic layer, wherein the microstructure of the first catalytic layer comprises a plurality of orderly arranged nano units so as to enable the first catalytic layer to be in an orderly nano array, wherein the nano units are arranged in a gradient manner in the forming process to form a gradient structure, the catalyst content is gradually reduced from the surface of the nano units to the inside, and the three-dimensional resin content is gradually increased from the surface of the nano units to the inside;
s3: placing the first catalytic layer with the AAO template in a vacuum oven for negative pressure treatment;
s4: carrying out transfer printing treatment on the first catalytic layer with the AAO template and the proton exchange membrane by hot pressing;
s5: and (3) carrying out alkaline cleaning treatment and protonation treatment on the structure to obtain the membrane electrode with the graded and ordered first catalytic layer.
6. The method for producing a membrane electrode according to claim 5, wherein: the components of the catalyst slurry in the step S1 include the catalyst, a stereogenic resin, water and alcohol, wherein the stereogenic resin forms the catalyst slurry in the form of a solution, the stereogenic resin solution is a perfluorosulfonic acid resin solution, and the mass ratio of the catalyst, the stereogenic resin solution, the water and the alcohol is 1: (1-10): (1-50): (1-50); the specific steps for preparing the catalyst slurry include: mixing the catalyst, the three-dimensional resin solution, water and alcohol, and carrying out ultrasonic treatment for 0.1-4 h.
7. The method for producing a membrane electrode according to claim 5, wherein: in the step S2, the treatment mode of the gradient structure is layer-by-layer coating or horizontal standing treatment; when the layer-by-layer coating mode is adopted, the concrete steps comprise coating the catalyst slurry with different stereo resin contents on the surface of the AAO template layer by layer from low to high in stereo resin content for 2-8 times; when the horizontal standing treatment mode is adopted, the time range of the horizontal standing treatment is 0-10 h, the temperature range is 0-50 ℃, and the time range does not comprise an endpoint value.
8. The method according to claim 5, wherein the negative pressure treatment conditions in step S3 are: the temperature range is 0-50 ℃, the negative pressure range is-0.1-0 MPa, and the time range is 0-50 h, wherein the time range does not comprise an endpoint value.
9. The method according to claim 5, wherein the hot pressing and transfer printing conditions in step S4 are: the temperature range is 60-200 ℃, the pressure range is 5-60 MPa, and the time range is 3 min-20 h.
10. The method for preparing a membrane electrode according to claim 5, wherein the specific steps of step S5 are: soaking a membrane electrode with the AAO template in a sodium hydroxide solution for alkaline washing, wherein the alkaline washing condition is that 0.1-10M NaOH is used for soaking, the alkaline washing time is 5-60 h, and the alkaline washing temperature is 10-60 ℃; then soaking the membrane electrode with the AAO template washed away in dilute sulfuric acid for protonation under the condition of 0.1-2M H 2 SO 4 Soaking, wherein the protonation time ranges from 12h to 60h, and the protonation temperature ranges from 10 ℃ to 60 ℃.
11. Use of a membrane electrode according to any one of claims 1 to 4, characterized in that: the membrane electrode is applied to proton exchange membrane electrolyzed water or anion exchange membrane electrolyzed water.
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