Membrane electrode assembly and method for electrolytic hydrogen production

Abstract

A membrane electrode assembly and a method for electrolysis to produce hydrogen are disclosed. The membrane electrode assembly includes a first electrode, a second electrode, and an anion exchange membrane sandwiched between the first electrode and the second electrode. The first electrode includes a first metal mesh, a first catalyst layer coated on the first metal mesh, a second metal mesh, and a second catalyst layer coated on the second metal mesh. The first metal mesh is located between the anion exchange membrane and the second metal mesh. The thickness of the second metal mesh is greater than the thickness of the first metal mesh. The thickness of the first catalyst layer is greater than the thickness of the second catalyst layer. The second catalyst layer is iron, cobalt, manganese, zinc, niobium, molybdenum, ruthenium, platinum, gold, or aluminum. The second catalyst layer is in a crystalline state.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a membrane electrode assembly, and a method for producing hydrogen by electrolysis using the membrane electrode assembly. BACKGROUND

[0002] In today's energy shortage, it is imperative to seek alternative energy, and hydrogen is the best alternative energy. Under the concept of environmental protection, the use of hydrogen as fuel is in line with the expectations of environmental protection. Electrolysis of water is the simplest way to produce hydrogen and oxygen. In the future development of green hydrogen source technology for carbon neutralization, alkaline water electrolysis hydrogen production has the advantages of low construction cost and long element durability, and is a forward-looking technology that is attracting international attention and being developed.

[0003] The use of clean renewable energy is the future development trend of the world. How to improve the efficiency of renewable energy, especially the part of excess electricity, is the focus of development of various countries. The use of water electrolysis hydrogen production technology is beneficial to adjust the excess electricity of renewable power. Therefore, improving the cost and efficiency of water electrolysis hydrogen production is an important cornerstone for future technology industrialization. The key is to effectively integrate various elements to improve electrolysis efficiency and reduce cost. Traditional electrolysis requires a flow layer to flow into an alkaline aqueous solution and discharge hydrogen and oxygen generated by electrolysis. However, the flow layer is manufactured by mechanical processing, which is expensive and increases the cost. In summary, there is an urgent need for a new membrane electrode assembly to omit the flow layer. SUMMARY

[0004] The membrane electrode assembly provided by an embodiment of the present disclosure includes: a first electrode; a second electrode; and an anion exchange membrane disposed between the first electrode and the second electrode. The first electrode includes: a first metal mesh; a first catalyst layer coated on the first metal mesh; a second metal mesh; and a second catalyst layer coated on the second metal mesh. The first metal mesh is located between the anion exchange membrane and the second metal mesh. The thickness of the second metal mesh is greater than the thickness of the first metal mesh. The thickness of the first catalyst layer is greater than the thickness of the second catalyst layer. The second catalyst layer is iron, cobalt, manganese, zinc, niobium, molybdenum, ruthenium, platinum, gold, or aluminum. The second catalyst layer is in a crystalline state.

[0005] The method for producing hydrogen by electrolysis provided by an embodiment of the present disclosure includes: immersing a membrane electrode assembly in an alkaline aqueous solution, wherein the membrane electrode assembly includes: a first electrode; a second electrode; and an anion exchange membrane arranged between the first electrode and the second electrode, wherein the first electrode includes: a first metal mesh; a first catalyst layer coated on the first metal mesh; a second metal mesh; and a second catalyst layer coated on the second metal mesh, wherein the first metal mesh is located between the anion exchange membrane and the second metal mesh, the thickness of the second metal mesh is greater than the thickness of the first metal mesh, the thickness of the first catalyst layer is greater than the thickness of the second catalyst layer, the second catalyst layer is iron, cobalt, manganese, zinc, niobium, molybdenum, ruthenium, platinum, gold, or aluminum, and the second catalyst layer is in a crystalline state; and applying a potential to the first electrode and the second electrode to electrolyze the alkaline aqueous solution, so that one of the first electrode and the second electrode produces hydrogen gas, and the other of the first electrode and the second electrode produces oxygen gas. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 A schematic diagram of an electrolysis hydrogen production device in an embodiment;

[0007] Figure 2 A schematic diagram of an electrolysis hydrogen production device in an embodiment;

[0008] Figure 3 An OER curve of iron-nickel meshes formed by iron precursor solutions with different concentrations in an embodiment;

[0009] Figure 4 An OER curve of cobalt-nickel meshes formed by cobalt precursor solutions with different concentrations in an embodiment;

[0010] Figure 5 An HER curve of cobalt-nickel meshes formed by cobalt precursor solutions with different concentrations in an embodiment;

[0011] Figure 6 A current-voltage curve of a membrane electrode assembly in an embodiment;

[0012] Figure 7 A current-voltage curve of a membrane electrode assembly in an embodiment;

[0013] Figure 8 A current-voltage curve of a membrane electrode assembly in an embodiment;

[0014] Figure 9 A current-voltage curve of a membrane electrode assembly after operating for 60 hours in an embodiment;

[0015] Figure 10 A current-voltage curve of a membrane electrode assembly in an embodiment;

[0016] Figure 111 is a comparison diagram of current-voltage curves of different membrane electrode assemblies in one embodiment.

[0017] Explanation of symbols

[0018] 10,20: membrane electrode assembly

[0019] 11: Anode

[0020] 11A, 11B, 15A, 15B: Metal mesh

[0021] 13: Anion exchange membrane

[0022] 15: cathode

[0023] 17: Runner layer

[0024] 19: Collector

[0025] 100,200: Electrolysis hydrogen production device DETAILED DESCRIPTION

[0026] The electrolysis hydrogen production device 100 provided in one embodiment of the present disclosure is as follows Figure 1 As shown, an anion exchange membrane 13 is sandwiched between an anode 11 and a cathode 15 to form a membrane electrode assembly (MEA) 10, and the MEA 10 is sandwiched between two current collectors 19. To input reactants, such as an alkaline aqueous solution, into the MEA 10 and discharge products, such as hydrogen and oxygen, from the MEA, a flow channel layer 17 is required, sandwiched between the current collector 19 and the anode 11, and another flow channel layer 17 is required, sandwiched between the current collector 19 and the cathode 15. Generally speaking, the production cost of the flow channel layer 17 is relatively high, which increases the cost of the electrolytic hydrogen production device 100.

[0027] In order to overcome the problem of the flow channel layer, the electrolysis hydrogen production device 200 provided in one embodiment of the present disclosure is as follows: Figure 2 As shown, it includes a membrane electrode assembly 20 sandwiched between two current collecting materials 19. The membrane electrode assembly 20 includes an anode 11; a cathode 15; and an anion exchange membrane 13, which is sandwiched between the anode 11 and the cathode 15. The anode 11 includes a metal mesh 11A having a catalyst layer C1 (not shown) coated thereon; and a metal mesh 11B having a catalyst layer C2 (not shown) coated thereon. The metal mesh 11A is located between the anion exchange membrane 13 and the metal mesh 11B. For example, the metal mesh 11A can be a stainless steel mesh, a titanium mesh, a nickel mesh, a nickel alloy mesh, a niobium alloy mesh, a copper mesh, or an aluminum mesh. The catalyst layer C1 has a chemical structure of M' a M” b N2, M' c M” d C e , or M x Ru yN2, wherein M' is Ni, Co, Fe, Mn, Cr, V, Ti, Cu, or Zn, M" is Nb, Ta, or a combination thereof, M is Ni, Co, Fe, Mn, Cr, V, Ti, Cu, or Zn, 0.7≤a≤1.7, 0.3≤b≤1.3, a+b=2, 0.24≤c≤1.7, 0.3≤d≤1.76, 0.38≤e≤3.61, 0 a M" b N2is cubic, M' c M" d C e is cubic or amorphous, and M x Ru y N2is cubic or amorphous. The metal mesh 11A with the catalyst layer C1 coated thereon can refer to the applicant's filed Taiwan patent I677596. It is noted that the catalyst layer C1 is not limited to the catalyst composition mentioned above, but other commercially available catalysts suitable for anodes can be used.

[0028] On the other hand, the metal mesh 11B can be a stainless steel mesh, a titanium mesh, a nickel mesh, a nickel alloy mesh, a niobium alloy mesh, a copper mesh, or an aluminum mesh. The catalyst layer C2 is iron, cobalt, manganese, zinc, niobium, molybdenum, ruthenium, platinum, gold, or aluminum. In one embodiment, the catalyst layer C2 coated on the metal mesh 11B is iron, cobalt, zinc, niobium, molybdenum, ruthenium, platinum, or gold. Since the catalyst layer C2 coated on the metal mesh 11B is chemically reduced, a crystalline catalyst layer C2 can be formed. According to experimental results, the crystalline catalyst layer C2 has a better electrolytic hydrogen production effect than the amorphous catalyst layer C2. In addition, the thickness of the metal mesh 11B is greater than the thickness of the metal mesh 11A to replace the function of the flow layer. In one embodiment, the metal mesh 11A is a smooth-surfaced stainless steel mesh, and the metal mesh 11B is a rough-surfaced nickel foam. The metal mesh 11A can protect the anion exchange membrane 13 from being pierced by the metal mesh 11B to cause short-circuit failure of the device, and the metal mesh 11B can replace the high-cost flow layer and provide a better electrolytic hydrogen production effect than the flow layer. On the other hand, the thickness of the catalyst layer C1 is greater than the thickness of the catalyst layer C2, the thickness of C1 is between 0.25 microns and 1 micron, and the thickness of C2 is between 0.01 microns and 0.25 microns. If the thickness of the catalyst layer C1 is less than or equal to the thickness of the catalyst layer C2, the electrolytic hydrogen production effect is not good.

[0029] As Figure 2As shown, the cathode 15 includes a metal mesh 15A with a catalyst layer C3 (not shown) coated thereon, and a metal mesh 15B with a catalyst layer C4 (not shown) coated thereon. The metal mesh 15A is located between the anion exchange membrane 13 and the metal mesh 15B. For example, the metal mesh 15A can be a stainless steel mesh, a titanium mesh, a nickel mesh, a nickel alloy mesh, a niobium alloy mesh, a copper mesh, or an aluminum mesh. The chemical structure of the catalyst layer C3 is M x Ru y N2or M x Ru y wherein M is Ni, Co, Fe, Mn, Cr, V, Ti, Cu, or Zn, 0 < x < 1.3, 0.7 < y < 2, x + y = 2, M x Ru y N2is cubic or amorphous, and M x Ru y is cubic. The metal mesh 15A with the catalyst layer C3 coated thereon can refer to the Taiwan patent I677596 filed by the applicant. It is noted that the catalyst layer C3 is not limited to the above-mentioned catalyst composition, and other commercially available catalysts suitable for cathodes can be used.

[0030] On the other hand, the metal mesh 15B can be a stainless steel mesh, a titanium mesh, a nickel mesh, a nickel alloy mesh, a niobium alloy mesh, a copper mesh, or an aluminum mesh. The catalyst layer C4 is iron, cobalt, manganese, zinc, niobium, molybdenum, ruthenium, platinum, gold, or aluminum. In one embodiment, the catalyst layer C4 coated on the metal mesh 15B is iron, cobalt, manganese, zinc, niobium, molybdenum, gold, or aluminum. Since the coating of the catalyst layer C4 on the metal mesh 15B is a chemical reduction, a crystalline catalyst layer C4 can be formed. According to experimental results, the crystalline catalyst layer C4 has a better electrolytic hydrogen production effect than the amorphous catalyst layer C4. In addition, the thickness of the metal mesh 15B is greater than the thickness of the metal mesh 15A to replace the function of the flow layer. In one embodiment, the metal mesh 15A is a smooth surface stainless steel mesh, and the metal mesh 15B is a rough surface nickel foam. The metal mesh 15A can protect the anion exchange membrane 13 from being pierced by the metal mesh 15B to cause short circuit failure of the device, and the metal mesh 15B can replace the high-cost flow layer and provide a better electrolytic hydrogen production effect than the flow layer. On the other hand, the thickness of the catalyst layer C3 is greater than the thickness of the catalyst layer C4, the thickness of C3 is between 10 microns and 100 microns, and the thickness of C4 is between 0.01 microns and 0.25 microns. If the thickness of the catalyst layer C3 is less than or equal to the thickness of the catalyst layer C4, the electrolytic hydrogen production effect is not good.

[0031] In one embodiment, the anion exchange membrane 13 can be an imidazole polymer containing halogen ions or other suitable materials. For example, the anion exchange membrane 13 can be FAS available from Fumatech or X37-50 available from Dioxidematerials. Since the membrane electrode assembly 200 is used for electrolysis of alkaline aqueous solution to produce hydrogen, an anion exchange membrane 13 is used instead of other ion exchange membranes. In some embodiments, the current collector can be a stainless steel plate, a titanium plate, or other suitable plate.

[0032] Since the metal mesh 1 IB of the anode 11 and the metal mesh 15B of the cathode 15 have the function of flow channel layer, no additional flow layer is needed between the membrane electrode assembly 200 and the current collector 19. It is worth noting that, Figure 2 The anode 11 and the cathode 15 in the above embodiment both use the design of two layers of metal mesh, but the embodiments of the present disclosure are not limited thereto. For example, the anode can use other commercially available anodes other than metal mesh to match the flow channel layer, and only the cathode uses two layers of metal mesh to omit the design of flow channel layer. On the other hand, the cathode can use other commercially available cathodes other than metal mesh to match the flow channel layer, and only the anode uses two layers of metal mesh to omit the design of flow channel layer. In other words, the membrane electrode assembly can use two layers of metal mesh on only one side to omit the flow channel layer, and use the traditional flow channel layer on the other side.

[0033] In some embodiments, the thickness of the catalyst layer C1 is between 0.25 microns and 1 micron, and the thickness of the catalyst layer C3 is between 10 microns and 100 microns. If the thickness of the catalyst layer C1 or the catalyst layer C3 is too small, the effect of electrolysis to produce hydrogen is not good. If the thickness of the catalyst layer C1 or the catalyst layer C3 is too large, the effect of electrolysis to produce hydrogen is not good. In some embodiments, the thickness of the catalyst layer C2 (or the catalyst layer C4) is between 0.01 microns and 0.25 microns. If the thickness of the catalyst layer C2 or the catalyst layer C4 is too small, the effect is similar to that without the catalyst layer. If the thickness of the catalyst layer C2 or the catalyst layer C4 is too large, the electrolysis efficiency of the membrane electrode assembly to produce hydrogen is reduced.

[0034] In some embodiments, the hole size of the metal mesh 1 IB or the metal mesh 15B is 60 microns to 120 microns. If the hole size of the metal mesh 1 IB or the metal mesh 15B is too small, the reactants such as alkaline aqueous solution cannot be effectively input into the membrane electrode assembly 200, or the gas products (such as hydrogen and oxygen) cannot be effectively output from the membrane electrode assembly 200. If the hole size of the metal mesh 1 IB or the metal mesh 15B is too large, the electrolysis efficiency to produce hydrogen cannot be maintained for a long time (i.e., the decay after a long period of use is large).

[0035] In some embodiments, the weight ratio of the metal mesh 1 IB to the catalyst layer C2 (or the weight ratio of the metal mesh 15B to the catalyst layer C4) is 90:10 to 99.9:0.1. If the weight ratio is too low (i.e., the amount of catalyst layer is too high), the efficiency of hydrogen production by electrolysis is not good. If the weight ratio is too high (i.e., the amount of catalyst layer is too low), the effect is similar to that without the catalyst layer.

[0036] In some embodiments, the metal mesh 1 IB with the catalyst layer C2 coated thereon can be the same as the metal mesh 15B with the catalyst layer C4 coated thereon. In other embodiments, the metal mesh 1 IB with the catalyst layer C2 coated thereon can be different from the metal mesh 15B with the catalyst layer C4 coated thereon, such as different catalyst types, different mesh apertures, different mesh thicknesses, or a combination thereof. For example, the catalyst layer C2 coated on the metal mesh 1 IB can employ iron, and the catalyst layer C4 coated on the metal mesh 15B can employ cobalt or gold.

[0037] One embodiment of the present disclosure provides a method of producing hydrogen by electrolysis, which includes immersing the membrane electrode assembly 20 described above in an alkaline aqueous solution. The membrane electrode assembly 20 is similar to the foregoing and is not described in detail here. Then, an electric potential is applied to the anode 11 and the cathode 15 to electrolyze the alkaline aqueous solution, so that the cathode 15 generates hydrogen gas and the anode 11 generates oxygen gas. In one embodiment, the pH of the alkaline aqueous solution is greater than or equal to 13. If the pH of the alkaline aqueous solution is too low, the conductivity is not good. In one embodiment, the pH of the alkaline aqueous solution is 14.

[0038] In order to make the above content and other purposes, features, and advantages of the present disclosure more obvious and easy to understand, the following preferred embodiments are specifically described below with reference to the accompanying drawings:

[0039] [Embodiments]

[0040] Example 1 (foamed nickel mesh coated with different metals)

[0041] A commercially available foamed nickel mesh (GF28024657 from MERCK) was pretreated by (1) soaking in acetone for 15 minutes with ultrasonic agitation; (2) washing with deionized water for 10 minutes; (3) soaking in 10 wt% HC1 and washing with ultrasonic agitation for 30 minutes followed by water washing; and (4) drying in a vacuum oven at 50 °C. After the pretreatment procedure was completed, a 250 mM metal precursor solution (metal includes Fe, Co, Mn, Zn, Nb, Mo, Cu, Ru, Pt, Au, Al, or Cr) was prepared and the foamed nickel mesh was then soaked in the metal precursor solution and stirred for 3 hours. The surface was then rinsed with deionized water until the effluent was clear and excess water was removed with a paper towel. Finally, the metal-nickel mesh sample was dried in a 90 °C hot air circulation oven. The metal in the above sample was crystalline as determined by transmission electron microscopy (TEM) diffraction pattern. It is noted that the above method of coating a nickel mesh with a metal is a chemical reduction and thus a crystalline phase of the metal can be formed. If other methods such as electroplating are used, the metal formed on the nickel mesh is amorphous. The electrochemical performance of the half-cell was measured in 1 M KOH solution using an Ag / AgCl reference electrode followed by EIS and LSV measurements for OER (oxygen evolution reaction) and HER. In the EIS measurements, the scan range for OER and HER was 0.1 to 10,000 Hz; in the LSV measurements for OER, the scan voltage range was 1.0 to 2.0 V, the scan rate was 10 mV / s, and the number of scans was 3. In the LSV measurements for HER, the scan voltage range was 0 to -0.4 V, the scan rate was 10 mV / s, and the number of scans was 3.

[0042] Table 1

[0043]

[0044]

[0045] From Table 1, it can be seen that the non-noble metal portion of the Co-nickel mesh has the best HER performance with an overpotential of 147 mV at a current value of 10 mA / cm 2 2 2

[0046] Example 2 (Foamed Nickel Mesh Coated with Different Amounts of Different Metals)

[0047] ​​​The concentration of the metal precursor solution (metal includes Fe, Co, Mn, Zn, Nb, Mo, Cu, Ru, Pt, Au, Al, or Cr) was adjusted, and the foamed nickel mesh was then immersed in the metal precursor solution and stirred for 3 hours. The surface was then rinsed with deionized water until the exuded liquid was transparent, and the excess water was absorbed with a wiping paper. Finally, the sample was dried in a 90°C hot air circulation oven, and the metal-nickel mesh sample was completed. The amount of metal coated on the nickel mesh, the HER activity, and the OER activity of different metals are shown in Tables 2 and 3, and the measurement methods of the HER activity and the OER activity are the same as described above.

[0048] Table 2

[0049]

[0050]

[0051] Table 3

[0052]

[0053] From Tables 2 and 3, it can be seen that the amount of metal coated on the nickel mesh (e.g., less than or equal to 10 wt% / at%) is not high, and the HER activity or the OER activity is sufficient.

[0054] Example 3

[0055] A plurality of foamed nickel meshes were immersed in different concentrations of iron precursor solutions, respectively, and stirred for 3 hours. The surface was then rinsed with deionized water until the exuded liquid was transparent, and the excess water was absorbed with a wiping paper. Finally, the sample was dried in a 90°C hot air circulation oven, and the iron-nickel mesh sample was completed. The iron-nickel mesh samples formed by different concentrations of iron precursor solutions were analyzed by energy dispersive X-ray for elemental analysis, and the measurement results of the HER activity and the OER activity of different samples are shown in Table 4. The measurement methods of the HER and the OER are the same as described above. In addition, the OER curves of the iron-nickel mesh samples formed by different concentrations of iron precursor solutions are shown in FIG. 2, in which the horizontal axis is the potential (V) relative to the reversible hydrogen electrode (RHE), and the vertical axis is the current density (J, mA / cm Figure 3 2 ). From Table 4, it can be seen that a small amount of iron coated on the nickel mesh has an effect of improving the HER and the OER.

[0056] Table 4

[0057]

[0058] Example 4

[0059] ​Immerse multiple foamed nickel meshes in cobalt precursor solutions of different concentrations and stir for 3 hours. Then rinse the surface with deionized water until the exudate is transparent, and absorb excess water with a wipe. Finally, dry it in a 90°C hot air circulation oven to complete the iron-nickel mesh sample. The cobalt-nickel mesh samples formed by cobalt precursor solutions of different concentrations were subjected to energy dispersive X-ray analysis to measure the element ratio. The HER activity and OER activity of different samples are measured as shown in Table 5. The measurement method of HER and OER is the same as above. The OER curves of the cobalt-nickel mesh formed by cobalt precursor solutions of different concentrations are shown in Table 5. Figure 4 As shown, the horizontal axis is the potential (V) relative to the reversible hydrogen electrode (RHE), and the vertical axis is the current density (J, mA / cm 2 ). The HER curves of the cobalt-nickel network formed by cobalt precursor solutions with different concentrations are shown in Figure 2. Figure 5 As shown in Table 5, the horizontal axis is the potential (V) relative to the reversible hydrogen electrode (RHE), and the vertical axis is the current density (J, mA / cm2). As shown in Table 5, a small amount of cobalt coating on the nickel mesh can improve the HER and OER effects.

[0060] Table 5

[0061]

[0062]

[0063] Example 5

[0064] Commercial PtC was used as a catalyst coated on conductive carbon paper and a nickel mesh (pore size of 91 microns) was used as the cathode for HER. A commercial DSA insoluble anode (IrO2 / RuO2-Ti mesh) and a nickel mesh (pore size of 91 microns) were used as the anode for OER. An anion exchange membrane X37-50 (purchased from Dioxide Materials) was sandwiched between the PtC-carbon paper at the cathode and the DSA electrode at the anode to form a membrane electrode assembly. The membrane electrode assembly was sandwiched between two stainless steel collectors and immersed in a 2M KOH solution. The electrochemical activity test was performed as follows. The scanning voltage range was: 1.2-2.2V, and the scanning rate was 50mV / s. The above-mentioned membrane electrode assembly can generate a current of 5.18A at 2V. The potential of the membrane electrode assembly was controlled at 2V and the operation was continued for 1000 minutes. The current it generated decayed by about 4.6%.

[0065] The above experiment was repeated, except that the mesh size of the nickel mesh was changed to 151 microns. The rest of the components of the membrane electrode assembly were the same as in the method of electrochemical activity test. The above membrane electrode assembly produced a current of 5.42 A at 2 V. The potential of the membrane electrode assembly was controlled at 2 V and operated for 1000 minutes, and the current produced was degraded by about 26.2%.

[0066] The above experiment was repeated, except that the mesh size of the nickel mesh was changed to 151 microns. The rest of the components of the membrane electrode assembly were the same as in the method of electrochemical activity test. The above membrane electrode assembly produced a current of 5.42 A at 2 V. The potential of the membrane electrode assembly was controlled at 2 V and operated for 1000 minutes, and the current produced was degraded by about 26.2%.

[0067] Example 6-1

[0068] Example 6-1 0.065 Ru 1.935 The catalyst was prepared on a conductive carbon paper as the cathode for HER, and the Ni 1.5 Nb 0.5 The N2-stainless steel mesh was used as the anode for OER, and a commercial anion exchange membrane X37-50 (purchased from Dioxide Materials) was sandwiched between the cathode and the anode to form a membrane electrode assembly. The membrane electrode assembly was sandwiched between two pieces of stainless steel current collectors, and the Ni 0.065 Ru 1.935 The conductive carbon paper and the current collector were sandwiched with a serpentine flow channel layer, and the Ni 1.5 Nb 0.5 The N2-stainless steel mesh and the current collector were sandwiched with a serpentine flow channel layer. The above membrane electrode assembly was immersed in a 2 M KOH solution, and the LSV electrochemical activity test was performed as follows. The scan voltage range was 1.0-2.0 V, and the scan rate was 50 mV / s. The current-voltage curve of the above membrane electrode assembly is shown in Figure 6

[0069] Example 6-2

[0070] The membrane electrode assembly was similar to that of Example 6-1, except that the Ni 1.5 Nb 0.5 The N2-stainless steel mesh and the Co-coated nickel mesh (as in Example 1) were used as the anode for OER, and the Ni 1.5 Nb 0.5 The N2-stainless steel mesh and the current collector were sandwiched with a serpentine flow channel layer. The rest of the components of the membrane electrode assembly were the same as in the method of electrochemical activity test. The current-voltage curve of the above membrane electrode assembly is shown in Figure 7

[0071] Example 6-3​​

[0072] Similar to the membrane electrode assembly of Example 6-1, except that the Ni 0.75 Ru 1.25 N2-stainless steel mesh and Co-coated Ni mesh (as in Example 1) as the cathode for HER, and omitting the Ni 0.75 Ru 1.25 N2-stainless steel mesh and a serpentine flow field plate between the current collector. The remaining components of the membrane electrode assembly and the method of electrochemical activity testing are as above. The current-voltage curve of the above membrane electrode assembly after 60 hours of operation is shown in Figure 8

[0073] Example 6-4

[0074] Similar to the membrane electrode assembly of Example 6-1, except that the Ni 0.065 Ru 1.935 - conductive carbon paper and Ni mesh coated with different metals (as in Example 1) as the cathode for HER, and Ni 1.5 Nb 0.5 N2-stainless steel mesh and Ni mesh coated with different metals (as in Example 1) as the anode for OER, and omitting the Ni 0.065 Ru 1.935 - conductive carbon paper and a serpentine flow field layer between the current collector, and omitting the Ni 1.5 Nb 0.5 N2-stainless steel mesh and a serpentine flow field layer between the current collector. The remaining components of the membrane electrode assembly and the method of electrochemical activity testing are as above. The current-voltage curve of the above membrane electrode assembly after 60 hours of operation is shown in Figure 9

[0075] Example 7

[0076] Take Preparation Example 11 and Preparation Example 12 of Taiwan Patent I677596, and replace the Ni 0.065 Ru 1.935 - conductive carbon paper as the cathode for HER, Ni 1.5 Nb 0.5 N2-stainless steel mesh as the anode for OER, and sandwich a commercial anion exchange membrane X37-50 (purchased from Dioxide Materials) between the cathode and the anode to form a membrane electrode assembly. The membrane electrode assembly is sandwiched between two pieces of stainless steel current collector, and Ni 0.065 Ru 1.935- - conductive carbon paper and a chessboard flow field layer between the current collector, and Ni 1.5 Nb 0.5 ​​N2 - stainless steel mesh and current collector material between the chessboard flow layer. The above membrane electrode assembly immersed in 2M KOH solution, LSV electrochemical activity test as follows. The voltage range: 1.0 ~ 2.0V, scan rate of 50mV / s. The current-voltage curve of the above membrane electrode assembly as shown in Figure 10 Example 6-1, Example 6-2, Example 6-3, and Example 7 as shown in Figure 11 From the above comparison, only a single electrode (such as anode or cathode) using metal-nickel mesh, can improve the hydrogen production efficiency of the membrane electrode assembly and omit the flow layer on one side. If the anode and cathode are both used metal-nickel mesh, the hydrogen production efficiency of the membrane electrode assembly can be further improved and omit the flow layer on both sides.

[0077] Although the present application is disclosed in connection with several preferred embodiments, it should be understood that the application is not intended to be limited to the preferred embodiments. Any substitutions and modifications of any elements in the preferred embodiments can be made by those skilled in the art without departing from the spirit and scope of the present application as defined by the appended claims.

Claims

1. A membrane electrode assembly, characterized in that: include: a first electrode; a second electrode; as well as an anion exchange membrane, sandwiched between the first electrode and the second electrode, The first electrode comprises: First Metal Mesh; A first catalyst layer is coated on the first metal mesh; a second metal mesh; and The second catalyst layer is coated on the second metal mesh. The first metal mesh is located between the anion exchange membrane and the second metal mesh, The thickness of the second metal mesh is greater than that of the first metal mesh, the thickness of the first catalyst layer is greater than that of the second catalyst layer, and the second catalyst layer is crystalline. The first electrode is an anode, the second electrode is a cathode, and the second catalyst layer is iron, cobalt, zinc, niobium, molybdenum, ruthenium, platinum, or gold. where the chemical structure of the first catalyst layer is Ni a Nb b N2, Ni c Nb d C e , Co c Nb d C e , Ni x Ru y N2, or Mn x Ru y N2, 0.7 ≤ a ≤ 1.7, 0.3 ≤ b ≤ 1.3, a + b = 2, 0.24 ≤ c ≤ 1.7, 0.3 ≤ d ≤ 1.76, 0.38 ≤ e ≤ 3.61, 0 < x < 1.3, 0.7 < y < 2, and x + y = 2 Among them, Ni a Nb b N2 is a cubic crystal system, Ni c Nb d C e and Co c Nb d C e It is cubic or amorphous, and Ni x Ru y N2 and Mn x Ru y N2 is a cubic crystal or amorphous.

2. A membrane electrode assembly, characterized in that: include: a first electrode; a second electrode; as well as an anion exchange membrane, sandwiched between the first electrode and the second electrode, The first electrode comprises: First Metal Mesh; A first catalyst layer is coated on the first metal mesh; a second metal mesh; and The second catalyst layer is coated on the second metal mesh. The first metal mesh is located between the anion exchange membrane and the second metal mesh, The thickness of the second metal mesh is greater than that of the first metal mesh, the thickness of the first catalyst layer is greater than that of the second catalyst layer, and the second catalyst layer is crystalline. The first electrode is a cathode, the second electrode is an anode, and the second catalyst layer is iron, cobalt, manganese, zinc, niobium, molybdenum, gold, or aluminum. The chemical structure of the first catalyst layer is Ni x Ru y N2、Mn x Ru y N2, or Ni x Ru y , where 0 <x<1.3,0.7<y<2,x+y=2,Ni x Ru y N2 and Mn x Ru y N2 is cubic or amorphous, and Ni x Ru y It is a cubic crystal system. 3 . The membrane electrode assembly according to claim 1 , wherein the thickness of the first catalyst layer is between 0.25 μm and 1 μm, and the thickness of the second catalyst layer is between 0.01 μm and 0.25 μm. 4 . The membrane electrode assembly according to claim 1 , wherein a pore size of the second metal mesh is 60 μm to 120 μm. 5 . The membrane electrode assembly according to claim 1 , wherein a weight ratio of the second metal mesh to the second catalyst layer is 90:10 to 99.9:0.

1.

6. The membrane electrode assembly as described in claim 1 or 2 is sandwiched between a first collector material and a second collector material, wherein the first electrode is located between the anion exchange membrane and the first collector material, the second electrode is located between the anion exchange membrane and the second collector material, and there is no flow channel layer between the first electrode and the first collector material.

7. The membrane electrode assembly according to claim 1 or 2, wherein the second electrode comprises: Third metal mesh; a third catalyst layer coated on the third metal mesh; Fourth metal mesh; as well as The fourth catalyst layer is coated on the fourth metal mesh. The third metal mesh is located between the anion exchange membrane and the fourth metal mesh. The thickness of the fourth metal mesh is greater than that of the third metal mesh, the thickness of the third catalyst layer is greater than that of the fourth catalyst layer, the fourth catalyst layer is iron, cobalt, manganese, zinc, niobium, molybdenum, ruthenium, platinum, gold, or aluminum, and the fourth catalyst layer is crystalline.

8. The membrane electrode assembly as described in claim 7 is sandwiched between a first collector material and a second collector material, wherein the first electrode is located between the anion exchange membrane and the first collector material, the second electrode is located between the anion exchange membrane and the second collector material, there is no flow channel layer between the first electrode and the first collector material, and there is no flow channel layer between the second electrode and the second collector material.

9. A method for producing hydrogen by electrolysis, comprising: Immersing the membrane electrode assembly according to claim 1 or 2 in an alkaline aqueous solution; as well as A potential is applied to the first electrode and the second electrode to electrolyze the alkaline aqueous solution, so that one of the first electrode and the second electrode generates hydrogen and the other of the first electrode and the second electrode generates oxygen. 10 . The method for producing hydrogen by electrolysis as claimed in claim 9 , wherein the pH value of the alkaline aqueous solution is greater than or equal to 13.

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