Ordered anode GDE, membrane electrode assembly and application thereof

Abstract

The invention discloses an ordered anode GDE, a membrane electrode assembly and application thereof, and the ordered anode GDE comprises an ordered gas diffusion layer and an ordered anode catalyst layer; the ordered gas diffusion layer comprises ordered micron-sized porous titanium, transition metal and an oxide thereof, and the transition metal and the oxide thereof are attached to the surface of the porous titanium; the ordered anode catalyst layer comprises a semiconductor nanosheet array and oxygen evolution catalyst nanoparticles deposited on the surface of the semiconductor nanosheet array, and the semiconductor nanosheet array grows on the surface of the ordered gas diffusion layer; the semiconductor nanosheet array is perovskite structure oxide ABO3, A is alkaline earth metal or alkali metal element, B is transition metal element, and O is oxygen element. The ABO3 semiconductor nanosheet array is used as a carrier of the ordered anode catalyst layer, so that the utilization rate of the catalyst is increased, a gas-liquid transmission channel is improved, and the stability of the ordered anode GDE is improved.

Description

Technical Field

[0001] The invention relates to an ordered anode GDE, a membrane electrode assembly and applications thereof. Background Art

[0002] As a zero-carbon and efficient energy carrier, hydrogen has become an important part of the low-carbon energy solutions of countries around the world. Compared with the mature alkaline water electrolysis technology, the proton exchange membrane (PEM) water electrolysis technology, as a preliminary commercialized hydrogen production technology, has the characteristics of high hydrogen purity, high energy efficiency, simple maintenance, and fast response. It can better match the volatility and intermittency of renewable energy, so it has received widespread attention. The membrane electrode assembly (MEA) is recognized as the core component of the PEM electrolyzer, which is usually composed of a gas diffusion layer, a catalyst layer, and a proton exchange membrane. Among them, the catalyst layer is the place where the electrochemical reaction occurs and is the basis of the electrochemical activity and stability of the MEA. At present, the anode catalyst layer is mainly constructed using precious metal iridium-based and ruthenium-based catalysts with excellent oxygen evolution activity. However, iridium and ruthenium have low earth abundance and are expensive, so the reduction of precious metal loading in MEA has become the key to the large-scale production of MEA and the further development of PEM water electrolysis technology. The traditional membrane electrode preparation technology includes two steps: the first step is to prepare the electrocatalyst, organic solvent (ethanol, etc.), and binder Nafion into a uniform catalyst slurry; the second step is to load the catalyst onto the gas diffusion layer (GDL) by spraying, scraping, etc. to form a gas diffusion electrode (GDE), or a thin layer of coated membrane electrode (CCM) on the PEM. The preparation process of the traditional membrane electrode is mature, but under the action of the Nafion binder, the catalyst layer has the characteristics of looseness, porousness, and disordered microstructure. There are problems such as high precious metal loading, serious agglomeration of catalyst and binder, limited active sites for three-phase reaction, and high gas-liquid transmission resistance, resulting in poor overall performance of the electrolyzer.

[0003] Since the preparation method of precious metal nanocatalysts has a significant influence on the particle size, morphology, interface properties, spatial distribution, etc. of the catalyst, the catalytic layer is currently mainly prepared by magnetron sputtering, coating and calcination, etc. Summary of the invention

[0004] The present invention is made in order to at least partially achieve the goal of improving the utilization rate of the oxygen evolution catalyst, reducing the loading of the precious metal in the catalytic layer, reducing the mass transfer resistance of protons, electrons, reactants and products, thereby improving the performance of PEM water electrolysis and reducing the cost, and improving the stability of GDE and electrolyzer.

[0005] As a first aspect of the present invention, it relates to an ordered anode GDE, which comprises an ordered gas diffusion layer and an ordered anode catalyst layer;

[0006] The ordered gas diffusion layer comprises ordered micron-sized porous titanium, transition metal and oxide thereof, and the transition metal and oxide thereof are attached to the surface of the porous titanium;

[0007] The ordered anode catalyst layer includes a semiconductor nanosheet array and oxygen evolution catalyst nanoparticles deposited on the surface thereof, wherein the semiconductor nanosheet array grows on the surface of the ordered gas diffusion layer; the semiconductor nanosheet array is a perovskite structure oxide ABO3, wherein A is an alkaline earth metal or an alkali metal element, B is a transition metal element, and O is an oxygen element.

[0008] In one or some optional embodiments, the thickness of the semiconductor nanosheet array is 10-100 nm.

[0009] In one or some optional embodiments, the perovskite structure oxide ABO3 is BaTiO3, Ba5Ta4O 15 、Ba5Nb4O 15 , Sr2Nb2O7, NaTaO3, at least one of.

[0010] In one or some optional embodiments, the transition metal is attached to the porous titanium surface by pulsed laser deposition, atomic layer deposition, evaporation or magnetron sputtering.

[0011] In one or some preferred embodiments, the transition metal is attached to the porous titanium surface by magnetron sputtering.

[0012] In one or some preferred embodiments, the semiconductor nanosheet array is grown by an in-situ growth technique.

[0013] In one or some preferred embodiments, the semiconductor nanosheet array is grown by a hydrothermal method.

[0014] In one or some optional embodiments, the transition metal is at least one of titanium, tantalum and niobium; the transition metal oxide is TiO x 、TaO x 、NbO x At least one of the following, wherein the range of x is 0<x≤2.5.

[0015] In one or some optional embodiments, the deposition method of the oxygen evolution catalyst nanoparticles is a pyrolysis method, a spraying method, an adsorption method or a photodeposition method.

[0016] In one or some preferred embodiments, the deposition method of the oxygen evolution catalyst nanoparticles is photodeposition.

[0017] In one or some optional embodiments, the particle size of the oxygen evolution catalyst nanoparticles is not greater than 10 nm.

[0018] In one or some optional embodiments, the oxygen evolution catalyst is a metal-containing oxygen evolution catalyst; the metal is preferably at least one of the precious metals iridium and ruthenium.

[0019] In one or some optional embodiments, the loading amount of the noble metal in the ordered anode catalyst layer is 0-2 mg / cm 2 .

[0020] In one or some optional embodiments, the porosity of the porous titanium is not less than 40%, and the thickness is 0.1-1.5 mm.

[0021] In one or some optional embodiments, the porous titanium is a porous titanium-containing or titanium-plated material.

[0022] In one or some preferred embodiments, the porous titanium is a titanium mesh, a porous sintered titanium plate, a titanium fiber felt, a titanium alloy mesh, a porous sintered titanium alloy plate or a titanium alloy fiber felt.

[0023] As a second aspect of the present invention, it relates to a membrane electrode assembly, which includes an electrolyte membrane, a cathode catalyst, a cathode diffusion layer and the above-mentioned ordered anode GDE.

[0024] As a third aspect of the present invention, it relates to the application of the above-mentioned membrane electrode assembly in PEM water electrolysis.

[0025] The present invention adopts perovskite structure oxide ABO3 semiconductor nanosheet array as the carrier of the ordered anode catalyst layer, which effectively increases the active sites of the three-phase reaction, improves the utilization rate of the oxygen evolution catalyst, and reduces the loading of precious metals in the catalyst layer; at the same time, it also reduces the mass transfer resistance of protons, electrons, reactants and products, and improves the gas-liquid transmission channel; in addition, the unique photoelectric properties of semiconductors help to expand the loading methods of catalysts.

[0026] The ordered anode GDE provided by the present invention is used for PEM water electrolysis, which helps to realize low-cost, high-efficiency and high-stability PEM water electrolysis technology. In addition, the present invention can also be applied to renewable fuel cells and alkaline water electrolyzer hydrogen production technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the preparation principle of the ordered anode GDE provided by the present invention;

[0028] Figure 2 is a scanning electron microscope image of the catalytic layer after photodeposition of an iridium-containing oxygen evolution catalyst in Example 1;

[0029] Figure 3 is a transmission electron microscope image of the photo-deposited iridium-containing oxygen evolution catalyst in Example 1;

[0030] Figure 4 is a schematic diagram of a membrane electrode assembly MEA for a PEM electrolyzer provided in Example 1;

[0031] Figure 5 1 is the polarization curve of the membrane electrode assembly MEA prepared in Example 1, Comparative Example 1 and Example 8;

[0032] Figure 6 The Ba5Nb4O obtained in Example 2 15 XRD patterns of semiconductor nanosheet arrays. DETAILED DESCRIPTION

[0033] The following is a detailed description of the embodiments of the present invention: The embodiments of the present invention are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and processes are given, but the protection scope of the present invention is not limited to the following embodiments. The process parameters for which specific conditions are not specified in the following embodiments are generally based on conventional conditions.

[0034] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0035] The inventor referred to the patent CN108075139A, a basic cobalt carbonate ordered array, first prepared the basic cobalt carbonate nanorod array by hydrothermal method, then prepared metal oxide nanobelts on its surface, and finally deposited electrocatalysts on the surface of the nanobelts to obtain an ordered membrane electrode, but the ordered membrane electrode has poor stability in PEM water electrolysis. The inventor referred to the patent US20110151353A1, a nano-thin layer (NSTF) electrode preparation technology, and realized the deposition of metals such as platinum and iridium on the ordered nano whisker array by magnetron sputtering technology, and finally transferred it to the ion exchange membrane to prepare CCM. However, the shadow effect makes it impossible for magnetron sputtering technology to deposit a uniform thickness of precious metal catalyst layer on the surface of the array substrate. The inventor referred to the patent CN109518221A and realized the preparation of iridium-based catalysts on the surface of titanium, platinum and other substrates by coating and roasting technology, but there are many cracks on the surface of the catalyst layer.

[0036] Since the above methods failed to meet the inventor's expectations, the inventor made the present invention after further research. The present invention reduces the proportion of ineffective catalyst in the GDL voids by developing a simple and reliable oxygen evolution catalyst layer preparation technology, which can effectively improve the utilization rate of the catalyst and reduce the loading of precious metals in the catalyst layer.

[0037] It should be noted that the ordering referred to in the present invention refers to the ordering of the catalyst layer support structure, such as that mentioned in patent CN112981449B.

[0038] It should be noted that the semiconductor nanosheet array in the present invention is a perovskite structure oxide, and its general formula is ABO3. Among them, A is an alkaline earth metal or alkali metal element with a larger radius, such as Sr, Ba, Na, etc.; B is a transition metal element, such as Nb, Ti, Mn, Fe, Co, etc.; O is an oxygen element. From the structure of the perovskite structure oxide, A and O are in 12-coordination, and B and O are in 6-coordination. Well-known perovskite structure oxides include BaTiO3, Sr2Nb2O7, Ba5Ta4O 15 、Ba5Nb4O 15 Among them, Ba5Ta4O 15 、Ba5Nb4O 15 Perovskite structure oxides (AB 0.8 O3) has 0.2 cation vacancies at the B position. The present invention does not limit the specific composition of ABO3, as long as it has semiconductor properties and a flake morphology. The present invention prefers BaTiO3, Ba5Ta4O 15 、Ba5Nb4O 15 ABO3 with acid-resistant elements such as Ti, Ta, and Nb at the B position, such as NaTaO3 and Sr2Nb2O7, is used as a semiconductor nanosheet array to improve the electrochemical and mechanical stability of the ordered carrier in high potential and strong oxygen evolution environment.

[0039] The present invention does not limit the content of the semiconductor nanosheet array ABO3 in the ordered anode GDE, as long as the catalyst layer contains the semiconductor nanosheet array ABO3. The thickness of the semiconductor nanosheet array in the present invention is preferably 10-100nm, which has the advantages of large specific surface area and low resistance.

[0040] The present invention does not limit the growth method of the semiconductor nanosheet array, as long as the method can realize the assembly of ABO3 sheet materials in the ordered gas diffusion layer, for example, the ABO3 sheet material can be prepared by high temperature solid phase method, molten salt method and other techniques, and then the ABO3 sheet array can be constructed on porous titanium by powder bonding or screen printing and other methods. The growth method of the semiconductor nanosheet array in the present invention is preferably an in-situ growth technology, and further preferably a hydrothermal method, and the semiconductor nanosheet array prepared thereby has the advantages of low interface resistance, good mechanical properties, good repeatability and the like.

[0041] The porous titanium is not limited in the present invention, as long as it has a porous structure and contains titanium in its composition or is plated on its surface, for example, it can be a titanium mesh, a porous sintered titanium plate, a titanium fiber felt, a titanium alloy mesh, a porous sintered titanium alloy plate, a titanium alloy fiber felt, etc. Taking into account its mechanical properties, gas-liquid transmission resistance and other factors, the present invention preferably uses a porous sintered titanium plate with a porosity of not less than 40% and a thickness of 0.1-1.5 mm.

[0042] The present invention does not limit the deposition method of transition metals attached to the porous titanium surface, as long as the method can achieve transition metal coverage on the porous substrate, such as pulsed laser deposition, atomic layer deposition, evaporation, magnetron sputtering, etc. Magnetron sputtering is preferred because it has the advantages of fast deposition speed, good repeatability and uniform film thickness.

[0043] The present invention does not limit the deposition method of the metal-containing oxygen evolution catalyst, as long as the method can achieve the dispersion of the catalyst, such as pyrolysis, spraying, adsorption, photodeposition, etc. The photodeposition method is preferred in the present invention. During the photodeposition process, the photogenerated holes on the surface of the semiconductor nanosheet array oxidize the metal ions in the solution, achieving uniform deposition of the nano oxygen evolution catalyst on the surface of the semiconductor nanosheet, which in principle reduces the probability of the oxygen evolution catalyst being deposited in the gaps of the GDL to form an invalid catalyst, improves the utilization rate of the catalyst, and reduces the load of precious metals in the catalyst layer; and, compared with the physical deposition technology, the photodeposited oxygen evolution catalyst has better interface contact with the carrier. The preparation method of the present invention is simple, the deposition site and the thickness of the catalyst layer are controllable, and it is easy to scale up, so the dispersibility and activity of the metal-containing oxygen evolution catalyst prepared thereby are improved.

[0044] The composition of the metal-containing oxygen evolution catalyst is not limited in the present invention, as long as the composition can have oxygen evolution performance, for example, it can be an oxygen evolution catalyst containing Ir, an oxygen evolution catalyst containing Ru, an oxygen evolution catalyst containing IrO x Oxygen evolution catalyst, containing MnO x Oxygen evolution catalyst, containing CoO x Oxygen evolution catalysts containing Ir and Ru are preferred because they have the advantages of good acid resistance and high activity.

[0045] The present invention does not limit the particle size of the oxygen evolution catalyst nanoparticles and the loading amount of the precious metal in the ordered anode catalyst layer. Preferably, the particle size of the oxygen evolution catalyst is not greater than 10 nm, and the loading amount of the precious metal in the ordered anode catalyst layer is 0-2 mg / cm 2 , which has the advantages of large specific surface area, high oxygen evolution catalyst utilization and low precious metal loading in the MEA catalyst layer.

[0046] The present invention does not limit the content of transition metals and their oxides in the ordered gas diffusion layer, and the preferred content is 0.01-1%, which has the advantages of low interface resistance and high conductivity of the diffusion layer.

[0047] The present invention does not limit the crystal phase of the transition metal oxide in the ordered gas diffusion layer, as long as its composition contains transition metal and oxygen, and preferably an amorphous structure to reduce interface resistance.

[0048] The preparation principle of the ordered anode GDE of the embodiment of the present invention is as follows Figure 1 As shown, a semiconductor nanosheet array is first prepared by magnetron sputtering + anodic oxidation + hydrothermal method, and then an oxygen evolution catalyst is deposited on the surface of the semiconductor nanosheet array by a photodeposition method. The ordered anode GDE includes an ordered gas diffusion layer and an ordered anode catalyst layer; the ordered gas diffusion layer includes ordered micron-scale porous titanium, transition metals and oxides thereof, wherein the transition metals and oxides thereof are attached to the surface of the porous titanium; the ordered anode catalyst layer includes a semiconductor nanosheet array and oxygen evolution catalyst nanoparticles deposited on its surface, and the semiconductor nanosheet array grows on the surface of the ordered gas diffusion layer.

[0049] Example 1

[0050] (1) Preparation of metal Ta layer on the surface of porous sintered titanium plate by magnetron sputtering

[0051] First, the Ta target to be deposited and the porous sintered titanium plate (thickness of 1.4 mm, porosity of 40%, average pore size of 12 μm) were installed in the magnetron sputtering instrument as the target and substrate, and the distance between the two was adjusted to 70 mm. Then the magnetron sputtering chamber was evacuated to below 1 mPa, and argon was introduced as a carrier gas. Finally, the sputtering working pressure was adjusted to 3 Pa, the sputtering power was 60 W, and the sputtering was performed for 5 minutes to complete the preparation of the Ta layer on the surface of the porous sintered titanium plate.

[0052] (2) The metal Ta layer on the surface of the porous sintered titanium plate is converted into TaO by anodization x layer

[0053] Preparation of electrolyte: ammonium fluoride, water and ethylene glycol were mixed and stirred at 25° C. for 30 min to obtain an electrolyte; the concentration of ammonium fluoride in the electrolyte was 0.2 M, and the volume ratio of water to ethanol was 0.02.

[0054] A porous sintered titanium plate with a Ta layer deposited on the surface was used as the anode, a platinum sheet was used as the counter electrode, the reaction temperature was 25°C, the anodic oxidation voltage was 35V, and the time was 1200s.

[0055] (3) TaO was synthesized by hydrothermal method. x The layer transforms into Ba5Ta4O 15Semiconductor nanosheet arrays

[0056] After Ba(OH)2 was mixed with water, it was added to a porous sintered titanium plate with a transition metal oxide layer prepared on the surface, and then transferred to a hydrothermal autoclave, and the reaction temperature was set to 200°C and the reaction time was set to 24h.

[0057] (4) Photodeposition on Ba5Ta4O 15 Iridium-containing oxygen evolution catalyst deposited on the surface of nanosheet arrays

[0058] Prepare a photodeposition reaction liquid: dissolve potassium chloroiridate in deionized water, add potassium nitrate, and then stir at 25° C. for 30 minutes to obtain a photodeposition reaction liquid. In the photodeposition reaction liquid, the concentration of potassium chloroiridate is 0.3 mM, and the concentration of potassium nitrate is 0.3 mM.

[0059] The surface was prepared with Ba5Ta4O 15 The porous sintered titanium plate with a layer of 200 nm was placed in the photodeposition reaction solution and irradiated with a 400 W high pressure mercury lamp for 10 min. During the process, a circulating water pump was used to maintain the temperature of the reaction system at 10 °C.

[0060] Wash and dry, weigh the weight gain of the ordered anode GDE before and after photodeposition to be 10 mg, and divide it by the geometric area of ​​the ordered anode GDE (5 cm 2 ), it can be seen that the loading amount of precious metal iridium in the ordered anode catalyst layer formed by the iridium-containing oxygen evolution catalyst in the ordered anode GDE is 2 mg / cm 2 .

[0061] (5) Preparation and testing of membrane electrode

[0062] Pt / C catalyst was sprayed on the surface of the proton exchange membrane as the cathode, and then the prepared ordered anode GDE and porous sintered titanium plate were hot pressed onto the anode and cathode surfaces of the Nafion membrane, respectively, to prepare the membrane electrode assembly MEA. The steady-state polarization curve test was carried out at a temperature of 80°C. The test results are shown in Figure 5 As shown by Figure 5 It can be seen that 2A / cm 2 At a current density of 1.5 V, the cell voltage required for the membrane electrode assembly is only 1.92 V, which is better than the level reported in existing literature (usually greater than 2 V).

[0063] The scanning electron microscope image of the photodeposited iridium-containing oxygen evolution catalyst layer in this embodiment is as follows: Figure 2 As shown by Figure 2 Analysis shows that Ba5Ta4O 15The nanosheet array has a uniform morphology, and the morphology is still preserved after photodeposition (the thickness of the nanosheet is 10-20nm). The in-situ photodeposited iridium-containing oxygen evolution catalyst particles are uniform and controllably and evenly distributed on the surface of the nanosheet. The transmission electron microscopy image of the photodeposited iridium-based oxygen evolution catalyst in this example is as follows: Figure 3 As shown in the figure, the particle diameter of the iridium-containing oxygen evolution catalyst in the catalytic layer is 1-3nm, which further shows that the photodeposition technology can achieve in-situ, controllable and uniform deposition of the iridium-containing oxygen evolution catalyst on the carrier. The schematic diagram of the PEM membrane electrode assembly (MEA) composed of the ordered anode GDE and its water electrolysis principle are shown in Figure 4 As shown, the structure of MEA can be simply represented from left to right as: ordered anode GDE / ion exchange membrane / HER catalyst / cathode GDL.

[0064] Comparative Example 1

[0065] The porous sintered titanium plate was prepared under the same conditions as step (1) and step (2) to prepare TaO x The layer was then transferred to a hydrothermal reactor, the reaction temperature was set to 200°C, and the reaction time was 24h. Then, the iridium-containing oxygen evolution catalyst was photodeposited under the same conditions as step (4), and finally the membrane electrode was assembled and tested using step 5. The polarization curve is shown in Figure 5 As shown by Figure 5 It can be seen that 2A / cm 2 At the current density of , the required cell voltage of the membrane electrode assembly is 2.18V, indicating that Ba5Ta4O 15 Nanosheet arrays are beneficial to improving the performance of anode GDE.

[0066] Comparative Example 2

[0067] The method is the same as that of Comparative Example 1, except that step (4) is performed twice, and the loading of the noble metal iridium in the oxygen evolution catalyst reaches 4 mg / cm 2 .

[0068] Example 2

[0069] (1) Preparation of metallic Nb layer on porous titanium surface by magnetron sputtering

[0070] First, the Nb target to be deposited and the porous sintered titanium plate (thickness of 0.25 mm, porosity of 50%, average pore size of 5 μm) were installed in the magnetron sputtering instrument as the target and substrate, respectively, and the distance between the two was adjusted to 70 mm. Then the magnetron sputtering chamber was evacuated to below 1 mPa, and argon gas was introduced as a carrier gas. Finally, the sputtering working pressure was adjusted to 3 Pa, the sputtering power was 60 W, and the sputtering was performed for 5 minutes to complete the preparation of the Nb layer on the porous titanium surface.

[0071] (2) The metallic Nb layer on the surface of porous titanium is converted into NbO by anodizationx layer

[0072] Prepare an electrolyte: mix ammonium fluoride, water and ethylene glycol, and stir at 25° C. for 30 minutes to obtain an electrolyte; the concentration of ammonium fluoride in the electrolyte is 0.2 M, and the volume ratio of water to ethanol is 0.02.

[0073] The porous titanium with a Nb layer deposited on the surface was used as the anode, the counter electrode was a platinum sheet, the reaction temperature was 25°C, the anodic oxidation voltage was 35V, and the time was 1200s.

[0074] (3) NbO was synthesized by hydrothermal method. x The layer transforms to Ba5Nb4O 15 Semiconductor nanosheet arrays

[0075] After Ba(OH)2 was mixed with water, it was added to the porous titanium with a transition metal oxide layer prepared on the surface, and then transferred to a hydrothermal autoclave, and the reaction temperature was set to 200°C and the reaction time was set to 24h.

[0076] (4) Photodeposition on Ba5Nb4O 15 Iridium-containing oxygen evolution catalyst deposited on the surface of nanosheet arrays

[0077] Prepare a photodeposition reaction liquid: dissolve potassium chloroiridate in deionized water, add sodium nitrate, and then stir at 25° C. for 30 minutes to obtain a photodeposition reaction liquid. In the photodeposition reaction liquid, the concentration of potassium chloroiridate is 0.3 mM, and the concentration of sodium nitrate is 0.3 mM.

[0078] The surface was prepared with Ba5Nb4O 15 The porous titanium layer was placed in the photodeposition reaction solution and irradiated with a 400W high pressure mercury lamp for 10 minutes. During the process, a circulating water pump was used to maintain the temperature of the reaction system at 10°C.

[0079] Wash and dry, weigh the weight gain of the ordered anode GDE before and after photodeposition to be 10 mg, and divide it by the geometric area of ​​the ordered anode GDE (5 cm 2 ), it can be seen that the loading amount of precious metal iridium in the ordered anode catalyst layer formed by the iridium-containing oxygen evolution catalyst in the ordered anode GDE is 2 mg / cm 2 .

[0080] (5) Preparation and testing of membrane electrode

[0081] Pt / C catalyst is sprayed on the surface of the proton exchange membrane as the cathode, and then the prepared ordered anode GDE and porous titanium are hot-pressed onto the anode and cathode surfaces of the Nafion membrane respectively, thereby preparing a membrane electrode assembly MEA.

[0082] The Ba5Nb4O 15The XRD pattern of semiconductor nanosheet array is shown in Figure 6 As shown by Figure 6 Analysis shows that the peaks of porous titanium and metallic Nb appear in the XRD pattern, indicating that the preparation of semiconductor nanosheet arrays does not affect the existence of the transition metal layer structure.

[0083] Example 3

[0084] (1) Preparation of metal Ti layer on the surface of porous sintered titanium plate by magnetron sputtering

[0085] First, the Ti target to be deposited and the porous sintered titanium plate (thickness of 0.3mm, porosity of 60%) were installed in the magnetron sputtering instrument as the target and substrate, and the distance between them was adjusted to 70mm. Then the magnetron sputtering chamber was evacuated to below 1mPa, and argon was introduced as the carrier gas. Finally, the sputtering working pressure was adjusted to 3Pa, the sputtering power was 60W, and the sputtering was performed for 5min to complete the preparation of the Ti layer on the surface of the porous sintered titanium plate.

[0086] (2) The metal Ti layer on the surface of the porous sintered titanium plate is converted into TiO by anodization x layer

[0087] Prepare an electrolyte: mix ammonium fluoride, water and ethylene glycol, and stir at 25° C. for 30 minutes to obtain an electrolyte; the concentration of ammonium fluoride in the electrolyte is 0.2 M, and the volume ratio of water to ethanol is 0.02.

[0088] The porous sintered titanium plate with a Ti layer deposited on the surface was used as the anode, the counter electrode was a platinum sheet, the reaction temperature was 25°C, the anodic oxidation voltage was 35V, and the time was 1200s.

[0089] (3) TiO was prepared by hydrothermal method x Layer transformation into BaTiO3 semiconductor nanosheet array

[0090] After Ba(OH)2 was mixed with water, it was added to a porous sintered titanium plate with a transition metal oxide layer prepared on the surface, and then transferred to a hydrothermal autoclave, and the reaction temperature was set to 200°C and the reaction time was set to 24h.

[0091] (4) Deposition of iridium-containing oxygen evolution catalyst on the surface of BaTiO3 nanosheet arrays by photodeposition

[0092] Prepare the photodeposition reaction liquid: dissolve potassium chloroiridate in deionized water, add NaIO3, and then stir at 25°C for 30 minutes to obtain the photodeposition reaction liquid. In the photodeposition reaction liquid, the concentration of potassium chloroiridate is 0.3 mM, and the concentration of NaIO3 is 0.3 mM.

[0093] The porous sintered titanium plate with BaTiO3 layer prepared on the surface was placed in the photodeposition reaction solution and irradiated with a 300W high pressure mercury lamp for 10 minutes. During the process, a circulating water pump was used to maintain the temperature of the reaction system at 10°C.

[0094] Example 4

[0095] The method is the same as that of Example 2, except that the substrate used in step (1) is titanium felt (thickness 0.25 mm, porosity 70%), and SrCO3 is used as a strontium source in step 3 to form a Sr2Nb2O7 nanosheet array.

[0096] Example 5

[0097] The method is the same as that of Example 1, except that in step (1), a porous sintered titanium alloy plate (thickness 0.25 mm, porosity 50%, titanium content 99.8%, palladium content 0.2%) is used as the substrate, in step 3, NaOH is used as the sodium source to form a NaTaO3 nanosheet array, and in step 4, MnSO4 is used as the manganese source to form a MnO4-containing nanosheet array on the array. x of oxygen evolution catalyst.

[0098] Comparative Example 3

[0099] The method is the same as that of Example 5, except that NaOH is not used in step (3).

[0100] Example 6

[0101] The method is the same as that of Example 1, except that the anodization voltage in step (2) is 40 V, the anodization time is 2400 s, the hydrothermal reaction time in step 3 is 36 h, RuCl2 is used as a metal precursor in step 4, and the photodeposition time is 3 min. SEM characterization shows that the thickness of the nanosheets is 15-30 nm, and the thickness of the nanosheet array is about 100 nm.

[0102] Example 7

[0103] The method is the same as that of Example 1, except that the sputtering time in step (1) is 10 minutes, and chloroiridic acid is used as a metal precursor in step 4.

[0104] Example 8

[0105] The method is the same as that in Example 1, except that the deposition step of the iridium-containing oxygen evolution catalyst is to prepare Ba5Ta4O 15 Semiconductor nanosheet arrays were then coated on Ba5Ta4O 15The surface was then placed in a tube furnace and calcined at 450°C for 2h to obtain an ordered anode GDE containing IrO2 oxygen evolution catalyst. Finally, the membrane electrode was assembled using step (5) and tested. The polarization curve is shown in Figure 5 shown.

[0106] Depend on Figure 5 The polarization curve of membrane electrode assembly MEA shows that Ba5Ta4O 15 The nanosheet arrays and the photodeposited iridium-containing oxygen evolution catalyst produced a synergistic effect at 2 A / cm 2 , the single slot voltage at 80 degrees is only 1.98V.

[0107] Example 9

[0108] The method is the same as that in Example 1, except that the iridium-containing oxygen evolution catalyst is loaded on Ba5Ta4O by ultrasonic spraying. 15 The specific steps are as follows: first, commercial IrO2 oxygen evolution catalyst (Sigma-Aldrich, product number 206237), 5% Nafion solution, and deionized water are mixed by ultrasonic to prepare a catalyst slurry with a commercial IrO2 oxygen evolution catalyst concentration of 10 mg / mL, and then the semiconductor nanosheet array prepared in step (3) is fixed as a substrate on a vacuum hot stage at 80°C, and the catalyst slurry is evenly sprayed on the surface of the substrate by ultrasonic spraying. After the spraying is completed, the loading of precious metal iridium in the ordered anode catalyst layer is confirmed to be 2 mg / cm by differential weight method. 2 .

[0109] Example 10

[0110] The method is the same as that of Example 5, except that step (2) is omitted, Na2CO3 is used as a sodium source in step (3) to form a NaTaO3 semiconductor nanosheet array, and CoSO4 is used as a cobalt source in step (4) to form a CoO-containing nanosheet array on the array. x of oxygen evolution catalyst.

[0111] The membrane electrode assemblies MEAs prepared in Examples 1-10 of the present invention and Comparative Examples 1-3 were subjected to steady-state polarization curve tests at a temperature of 80° C. The cell pressure test results and the precious metal loading in the ordered anode catalyst layer are shown in Table 1.

[0112] Table 1

[0113]

[0114]

[0115] From the analysis of Table 1, it can be seen that under the same test conditions, the ordered structure transition metal oxide semiconductor nanosheet array prepared on the porous titanium surface by magnetron sputtering, anodic oxidation, and hydrothermal methods in the present invention effectively reduces the cell pressure, proving that the ordered structure is beneficial to improving the electrolysis water performance of the ordered anode GDE. Similarly, under the same precious metal loading, the metal-based oxygen evolution catalyst deposited on the nanosheet array by the photodeposition method has better electrolysis water performance than the oxygen evolution catalyst obtained by other deposition techniques. This shows that the transition metal oxide nanosheet array loaded with iridium-based oxygen evolution catalyst prepared by the method of the present invention can effectively improve the utilization rate of precious metal catalysts, reduce the mass transfer resistance of protons, electrons, reactants and products, and achieve the improvement of PEM electrolysis water performance and the reduction of cost.

[0116] Although the specific embodiments of the present invention have been described in detail, it will be understood by those skilled in the art. According to all the teachings disclosed, various modifications and replacements can be made to those details, and these changes are all within the protection scope of the present invention. The full scope of the present invention is given by the attached claims and any equivalents thereof.

Claims

1. Ordered anode GDE, characterized in that The ordered anode GDE comprises an ordered gas diffusion layer and an ordered anode catalyst layer; The ordered gas diffusion layer comprises ordered micron-sized porous titanium, transition metal and oxide thereof, and the transition metal and oxide thereof are attached to the surface of the porous titanium; The ordered anode catalyst layer includes a semiconductor nanosheet array and oxygen evolution catalyst nanoparticles deposited on the surface thereof, wherein the semiconductor nanosheet array grows on the surface of the ordered gas diffusion layer; the semiconductor nanosheet array is a perovskite structure oxide ABO3, wherein A is an alkaline earth metal or an alkali metal element, B is a transition metal element, and O is an oxygen element.

2. The ordered anode GDE according to claim 1, characterized in that The thickness of the semiconductor nanosheet array is 10-100 nm.

3. The ordered anode GDE according to claim 1, characterized in that The perovskite structure oxide ABO3 is BaTiO3, Ba5Ta4O 15 、Ba5Nb4O 15 , Sr2Nb2O7, NaTaO3, at least one of.

4. The ordered anode GDE according to claim 1, characterized in that The transition metal is attached to the surface of the porous titanium by pulse laser deposition, atomic layer deposition, evaporation or magnetron sputtering.

5. The ordered anode GDE according to claim 4, characterized in that The transition metal is attached to the surface of the porous titanium by magnetron sputtering.

6. The ordered anode GDE according to claim 1, characterized in that The growth method of the semiconductor nanosheet array is an in-situ growth technology.

7. The ordered anode GDE according to claim 6, characterized in that The growth method of the semiconductor nanosheet array is a hydrothermal method.

8. The ordered anode GDE according to claim 1, characterized in that The transition metal is at least one of titanium, tantalum and niobium; the transition metal oxide is TiO x 、TaO x 、NbO x At least one of the following, wherein the range of x is 0<x≤2.

5.

9. The ordered anode GDE according to claim 1, characterized in that The deposition method of the oxygen evolution catalyst nanoparticles is a thermal decomposition method, a spraying method, an adsorption method or a photodeposition method.

10. The ordered anode GDE according to claim 9, characterized in that The deposition method of the oxygen evolution catalyst nanoparticles is a photodeposition method.

11. The ordered anode GDE of claim 1, wherein: The particle size of the oxygen evolution catalyst nanoparticles is no greater than 10 nm.

12. The ordered anode GDE of claim 1, wherein: The oxygen evolution catalyst is a metal-containing oxygen evolution catalyst; the metal is preferably at least one of the noble metals iridium and ruthenium.

13. The ordered anode GDE of claim 1, wherein: The noble metal loading in the ordered anode catalyst layer is 0-2 mg / cm 2 .

14. The ordered anode GDE of claim 1, wherein: The porosity of the porous titanium is not less than 40%, and the thickness is 0.1-1.5 mm.

15. The ordered anode GDE of claim 1, wherein: The porous titanium is a porous titanium-containing or titanium-plated material.

16. The ordered anode GDE of claim 15, wherein: The porous titanium is a titanium mesh, a porous sintered titanium plate, a titanium fiber felt, a titanium alloy mesh, a porous sintered titanium alloy plate or a titanium alloy fiber felt.

17. A membrane electrode assembly, characterized in that The membrane electrode assembly comprises an electrolyte membrane, a cathode catalyst, a cathode diffusion layer and the ordered anode GDE according to any one of claims 1 to 16.

18. Use of the membrane electrode assembly according to claim 17 in PEM water electrolysis.

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