A flow channel plate, cathode structure for enhancing mass transfer, and electrolyzer

Abstract

The utility model discloses a flow channel plate, a cathode structure for enhancing mass transfer, and an electrolyzer, and relates to the field of electrochemistry. The flow channel plate disclosed in the first aspect of the utility model includes a plurality of parallel flow channels arranged on the flow channel plate, and each flow channel includes a plurality of smooth sections and narrowing sections arranged at intervals. The average width of the narrowing section is smaller than the width of the smooth section. Through the above arrangement, the flow channel has a plurality of narrowing sections and smooth sections in its length direction, thereby generating a variable flow resistance when a gas-liquid mixture flows through. At the same time, when the gas-liquid mixture flows through the narrowing section, the narrowing section generates a tangential force perpendicular to the length direction of the flow, which can break up the bubbles in the gas-liquid mixture.

Description

Technical Field

[0001] The utility model relates to the field of electrochemistry, in particular to a flow channel plate, a cathode structure for strengthening mass transfer and an electrolyzer. Background Art

[0002] Carbon dioxide electroreduction technology is a method of converting carbon dioxide into useful chemicals and fuels through renewable energy. This technology is of great significance to environmental protection and the realization of a carbon-neutral economy. Carbon dioxide electroreduction is an electrochemical process that can reduce carbon dioxide to other chemicals in an electrolyzer to achieve low-carbon or zero-carbon emissions. Convertible chemicals include chemicals such as methanol, ethylene, and methane, which are widely used in industry as fuels, plastics, and other important chemical raw materials. However, some challenges must be overcome to apply this technology on an industrial scale, including improving the energy efficiency of the process, selecting and optimizing suitable catalysts, designing efficient electrolyzer structures, and ensuring the economic feasibility of the entire process.

[0003] Currently, this technology is in a rapid development stage. Research focuses include developing new catalysts, improving reaction selectivity and efficiency, reducing costs, and integrating the use of renewable energy. With the advancement of technology and the realization of large-scale production, carbon dioxide electroreduction has the potential to become an important carbon capture and utilization technology.

[0004] Carbon dioxide electroreduction usually needs to be carried out in a specially designed electrolyzer, in which the anode performs the oxygen evolution reaction and the cathode performs the carbon dioxide electroreduction reaction. In practical applications, this technology faces some challenges, especially carbonate deposition and gas mass transfer problems, which seriously limit its popularization and industrial application. In terms of carbonate deposition, carbonates will gradually accumulate on the cathode surface during the electrolysis process. When these carbonates exceed their local solubility limit, precipitation will form. These precipitates will block the flow channel in the electrolyzer, resulting in a decrease in the efficiency of the electrolyzer, and may even cause the electrolyzer to stop working completely. This precipitation not only reduces the conversion efficiency of carbon dioxide, but also increases the equipment maintenance cost, making the economic feasibility of the entire process reduced. In terms of gas mass transfer, during the operation of the electrolyzer, if the gas diffusion layer is gradually infiltrated or even submerged by the electrolyte, the diffusion of carbon dioxide will become more difficult and it will be difficult to reach the surface of the membrane electrode efficiently. This will lead to a decrease in mass transfer efficiency, thereby reducing the carbon dioxide reduction efficiency of the entire electrolyzer.

[0005] Therefore, a flow channel plate that can enhance the diffusion of carbon dioxide is now being developed to prevent problems such as carbonate deposition and decreased mass transfer efficiency caused by the inability of carbon dioxide to diffuse. Utility Model Content

[0006] To solve the above-mentioned related problems, the utility model provides a flow channel plate in the first aspect, which includes a plurality of parallel flow channels arranged on the flow channel plate, each flow channel includes a plurality of smooth sections and narrowing sections arranged at intervals. The average width of the narrowing section is smaller than the width of the smooth section.

[0007] In a feasible implementation manner, the side wall of the narrowing section is in an inwardly convex arc shape, and the average width of the narrowing section decreases step by step along the flow direction L of the gas-liquid mixture.

[0008] In one possible implementation, the following formula is satisfied: Among them, B is the width of the smooth section; B1 is the width of the first narrowing section; L is the total length of flow channel 1; L1 is the length of one narrowing cycle.

[0009] In one possible implementation, the narrowing section satisfies the following formula: n =B1-nd. Among them, B n is the width of the nth narrowed segment; B1 is the width of the first narrowed segment; d is the degree of narrowing.

[0010] In a feasible implementation, the number of flow channels 100 is 8 to 15. The number of smooth sections 101 and the number of narrowed sections 102 are both 3 to 10.

[0011] The second aspect of the utility model provides a cathode structure for enhancing mass transfer, a cathode structure for enhancing mass transfer comprising a cathode end plate, a cathode flow channel plate, a cathode diffusion layer and an anion membrane which are detachably connected in sequence. A first cathode liquid inlet hole and a first cathode liquid outlet hole are provided on the cathode end plate, and a second cathode liquid inlet hole and a second cathode liquid outlet hole are provided on the cathode flow channel plate. The first cathode liquid inlet hole and the second cathode liquid inlet hole are connected, and the first cathode liquid outlet hole and the second cathode liquid outlet hole are connected. The cathode flow channel plate is a flow channel plate as provided in the first aspect of the utility model, and a plurality of cathode flow channels arranged in parallel are provided on the cathode flow channel plate, and each cathode flow channel includes a plurality of smooth sections and narrowing sections arranged at intervals. The average width of the narrowing section is smaller than the width of the smooth section. A catalyst is provided on the cathode diffusion layer.

[0012] The third aspect of the utility model provides an electrolyzer for enhancing mass transfer, comprising a cathode structure for enhancing mass transfer, an anode end plate, an anode flow channel plate and an anode diffusion layer as provided in the second aspect of the utility model. A first anode liquid inlet and a first anode liquid outlet are provided on the anode end plate, and a second anode liquid inlet and a second anode liquid outlet are provided on the anode flow channel plate. The first anode liquid inlet and the second anode liquid inlet are connected, and the first anode liquid outlet and the second anode liquid outlet are connected. The anode flow channel plate is a flow channel plate as claimed in the claim, and a plurality of parallel anode flow channels are provided on the anode flow channel plate. Each anode flow channel includes a plurality of smooth sections and narrowing sections arranged at intervals. The average width of the narrowing section is less than the width of the smooth section. A catalyst is provided on the anode diffusion layer.

[0013] In a specific embodiment, it also includes a cathode liquid inlet joint, an anode liquid inlet joint, a cathode liquid outlet joint and an anode liquid outlet joint. The cathode liquid inlet joint is connected to the first cathode liquid inlet hole, the anode liquid inlet joint is connected to the first anode liquid inlet hole, the cathode liquid outlet joint is connected to the first cathode liquid outlet hole, and the anode liquid outlet joint is connected to the first anode liquid outlet hole.

[0014] In a specific embodiment, a sealing ring is provided at the connection between the first cathode liquid inlet and the second cathode liquid inlet. A sealing ring is provided at the connection between the first cathode liquid outlet and the second cathode liquid outlet. A sealing ring is provided at the connection between the first anode liquid inlet and the second anode liquid inlet. A sealing ring is provided at the connection between the first anode liquid outlet and the second anode liquid outlet.

[0015] In a specific embodiment, the catalyst is selected from any one of a single atom catalyst, a single metal catalyst, an alloy catalyst, or a catalyst composed of copper, nickel, zinc, and alloys thereof.

[0016] Beneficial Effects

[0017] 1) The utility model designs a flow channel plate, on which a plurality of flow channels are arranged in parallel, and each of the flow channels includes a plurality of smooth sections and narrowing sections arranged at intervals. Among them, the average width of the narrowing section is smaller than the width of the smooth section. Through the above arrangement, the flow channel has a plurality of narrowing sections and smooth sections in its length direction, thereby generating a variable flow resistance when the gas-liquid mixture flows through. At the same time, when the gas-liquid mixture flows through the narrowing section, the narrowing section generates a tangential force perpendicular to the flow length direction, which can break up the bubbles in the gas-liquid mixture and prevent carbonate deposition.

[0018] 2) The flow channel plate designed in the utility model adopts a progressive narrowing method. Starting from the first narrowing section through which the gas-liquid mixture flows, the average width of each subsequent narrowing section is reduced. Through the above progressive narrowing method, a fluid dynamic environment suitable for the gas-liquid mixture at different stages is provided, thereby optimizing the performance of the electrolytic cell and improving the electrolysis efficiency.

[0019] 3) The utility model also designs a cathode structure for enhancing mass transfer, which includes a cathode end plate, a cathode flow channel plate, a cathode diffusion layer and an anion membrane that are detachably connected in sequence. Through the arrangement of the above structure, the flow and distribution of the gas-liquid mixture in the cathode diffusion layer are optimized, so that the gas can be evenly distributed on the surface of the cathode diffusion layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the flow channel plate of the utility model.

[0021] Figure 2 It is a structural schematic diagram of the flow channel of the utility model.

[0022] Figure 3 The utility model is a schematic diagram of the cathode structure and electrolyzer structure for enhancing mass transfer.

[0023] Figure 4 The flow mode of the gas-liquid mixture of the utility model is shown in FIG. Figure 1 .

[0024] Figure 5 The flow mode of the gas-liquid mixture of the utility model is shown in FIG. Figure 2 .

[0025] Reference numerals

[0026] Runner 100

[0027] Smooth segment 101

[0028] Narrowing section 102

[0029] Cathode terminal plate 1

[0030] The first cathode liquid inlet hole 11

[0031] The first cathode liquid outlet 12

[0032] Cathode liquid inlet connector 13

[0033] Cathode liquid outlet connector 14

[0034] Cathode channel plate 2

[0035] The second cathode liquid inlet hole 21

[0036] The second cathode liquid outlet hole 22

[0037] Cathode channel 23

[0038] Cathode diffusion layer 3

[0039] Anode end plate 1'

[0040] First anode liquid inlet hole 11'

[0041] First anode liquid outlet 12'

[0042] Anode liquid inlet connector 13'

[0043] Anode liquid outlet connector 14'

[0044] Anode channel plate 2'

[0045] Second anode liquid inlet hole 21'

[0046] Second anode liquid outlet 22'

[0047] Anode channel 23'

[0048] Anode diffusion layer 3'

[0049] Anion membrane 4 DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model. In the description of the utility model, it should be noted that the orientation or position relationship indicated by the terms "left side", "right side", "upper side", "lower side", "above", "below" and the like is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the utility model. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0051] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] In addition, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0053] Embodiment 1

[0054] This embodiment provides a flow channel plate, see Figure 1, the flow channel plate includes a plurality of parallel flow channels 100 arranged on the flow channel plate, and each flow channel 100 includes a plurality of smooth sections 101 and narrowing sections 102 arranged at intervals. The average width of the narrowing section 102 is smaller than the width of the smooth section 101. Such an arrangement enables the flow channel to have a plurality of narrowing sections 102 and smooth sections 101 in its length direction, thereby generating a variable flow resistance when the gas-liquid mixture flows through. At the same time, when the gas-liquid mixture flows through the narrowing section 102, the narrowing section 102 generates a tangential force perpendicular to the direction of the flow channel 100, and the tangential force can break up the bubbles in the gas-liquid mixture and prevent carbonate deposition. It is worth noting that the width B of the smooth section 101 and the average width B of the narrowing section 102 are n like Figure 2 As shown. In addition, the number of flow channels 100 is 8 to 15, and the number of smooth sections 101 and narrowing sections 102 are both 3 to 10. Preferably, the number of flow channels 100 is 14. The number of smooth sections 101 and narrowing sections 102 is 5.

[0055] In one specific embodiment, see Figure 1 The side wall of the narrowing section 102 is in an arc shape that bulges inward, and the average width of the narrowing section 102 gradually decreases along the flow direction T of the gas-liquid mixture. It is worth noting that the flow direction T of the gas-liquid mixture is as follows: Figure 2 shown.

[0056] In one possible embodiment, the flow channel 100 satisfies the following formula:

[0057]

[0058] Among them, see Figure 2 , B is the width of the smooth section 101; B1 is the average width of the first narrowing section 102; L is the total length of the flow channel 1; L1 is the length of one narrowing cycle. Preferably, B=3mm, B1=2.4mm, L=60mm, L1=12mm.

[0059] In another possible embodiment, the narrowing section 102 satisfies the following formula:

[0060] B n =B1-nd

[0061] Among them, see Figure 2 , B n is the width of the nth narrowing section 102; B1 is the width of the first narrowing section 102; d is the degree of narrowing. Preferably, n=5, B n =0.9, B1=2.4, d=0.3. By means of the above-mentioned progressive narrowing method, a suitable fluid dynamics environment for the gas-liquid mixture at different stages is provided, thereby optimizing the performance of the electrolytic cell and improving the electrolysis efficiency.

[0062] Embodiment 2

[0063] This embodiment provides a cathode structure for enhancing mass transfer. Figure 3 The cathode structure for enhancing mass transfer includes a cathode end plate 1, a cathode flow channel plate 2, a cathode diffusion layer 3 and an anion membrane 4 which are detachably connected in sequence. The cathode end plate 1 is provided with a first cathode liquid inlet hole 11 and a first cathode liquid outlet hole 12, and the cathode flow channel plate 2 is provided with a second cathode liquid inlet hole 21 and a second cathode liquid outlet hole 22. The first cathode liquid inlet hole 11 is connected to the second cathode liquid inlet hole 21, and the first cathode liquid outlet hole 12 is connected to the second cathode liquid outlet hole 22. Figure 1 The cathode flow channel plate 2 is the flow channel plate as described in the first embodiment, and a plurality of cathode flow channels 23 arranged in parallel are provided on the cathode flow channel plate 2, and each cathode flow channel 23 includes a plurality of smooth sections 101 and narrowing sections 102 arranged at intervals. The average width of the narrowing section 102 is smaller than the width of the smooth section 101. A catalyst is provided on the cathode diffusion layer 3. Through the arrangement of the above structure, the flow and distribution of the gas-liquid mixture in the cathode diffusion layer are optimized, so that the gas can be evenly distributed on the surface of the cathode diffusion layer.

[0064] It is worth noting that the cathode diffusion layer 3 includes a cathode frame plate and a cathode diffusion plate, wherein the cathode diffusion plate is arranged in the cathode frame plate and a catalyst is coated on the cathode diffusion plate. Specifically, the catalyst is a single-atom catalyst for CO2 electroreduction.

[0065] Embodiment 3

[0066] This embodiment is an electrolyzer for enhancing mass transfer, see Figure 3 , including a cathode structure for enhancing mass transfer as in Example 2, an anode end plate 1', an anode flow channel plate 2' and an anode diffusion layer 3'. A first anode liquid inlet hole 11' and a first anode liquid outlet hole 12' are provided on the anode end plate 1', and a second anode liquid inlet hole 21' and a second anode liquid outlet hole 22' are provided on the anode flow channel plate 2'; the first anode liquid inlet hole 11' and the second anode liquid inlet hole 21' are connected, and the first anode liquid outlet hole 12' and the second anode liquid outlet hole 22' are connected. The anode flow channel plate 2' is the flow channel plate as described in Example 1, and a plurality of parallel anode flow channels 23' are provided on the anode flow channel plate 2'. Each anode flow channel 23' includes a plurality of smooth sections 101 and narrowing sections 102 arranged at intervals. The average width of the narrowing section 102 is smaller than the width of the smooth section 101. A catalyst is provided on the anode diffusion layer 3'.

[0067] It is worth noting that, see Figure 3 The anode diffusion layer 3' comprises an anode frame plate and an anode diffusion plate, wherein the anode diffusion plate is arranged in the anode frame plate and a catalyst is coated on the anode diffusion plate. Specifically, the catalyst is a copper-nickel alloy catalyst for CO2 electroreduction.

[0068] In one specific embodiment, see Figure 3 , further comprising a cathode liquid inlet joint 13, an anode liquid inlet joint 13', a cathode liquid outlet joint 14 and an anode liquid outlet joint 14'. The cathode liquid inlet joint 13 is connected to the first cathode liquid inlet hole 11, and the anode liquid inlet joint 13' is connected to the first anode liquid inlet hole 11'. The cathode liquid outlet joint 14 is connected to the first cathode liquid outlet hole 12, and the anode liquid outlet joint 14' is connected to the first anode liquid outlet hole 12'.

[0069] In one specific embodiment, see Figure 3 A sealing ring is provided at the connection between the first cathode liquid inlet hole 11 and the second cathode liquid inlet hole 21; a sealing ring is provided at the connection between the first cathode liquid outlet hole 12 and the second cathode liquid outlet hole 22. A sealing ring is provided at the connection between the first anode liquid inlet hole 11' and the second anode liquid inlet hole 21'. A sealing ring is provided at the connection between the first anode liquid outlet hole 12' and the second anode liquid outlet hole 22'.

[0070] This embodiment also provides a method for using the electrolyzer for enhancing mass transfer, and the specific method for using is as follows:

[0071] 1) A gas-liquid mixture is introduced from the cathode liquid inlet joint 13. Here, the gas-liquid mixture is exemplified by a bicarbonate solution containing carbon dioxide. The bicarbonate solution enters the first cathode liquid inlet hole 11 through the cathode liquid inlet joint 13, and then enters the second cathode liquid inlet hole 21 through the first cathode liquid inlet hole 11. At the same time, a solution is also introduced into the anode liquid inlet joint 13'. Here, the solution is exemplified by a potassium hydroxide solution. The potassium hydroxide solution enters the first anode liquid inlet hole 11' through the anode liquid inlet joint 13', and then enters the second anode liquid inlet hole 21' through the first anode liquid inlet hole 11'.

[0072] 2) After the bicarbonate solution flows through the second cathode liquid inlet hole 21, it flows into each cathode flow channel 23 on the cathode flow channel plate 2. Since the smooth section 101 and the narrowed section 102 on the cathode flow channel 23 are constantly alternating, the bicarbonate solution can produce a variable flow resistance when it flows through. At the same time, the narrowed section 102 can produce a tangential force perpendicular to the flow direction T when the bicarbonate solution flows through, so that the gas in the bicarbonate solution can fully react with the catalyst on the cathode diffusion layer 3, thereby breaking up the bubbles in the gas-liquid mixture. At the same time, the potassium hydroxide solution flows through the second anode liquid inlet hole 21' and flows into each anode flow channel 23' on the anode flow channel plate 2'. Figure 4 and Figure 5 The figures shown are the flow modes of gas-liquid mixture.

[0073] 3) After flowing through each cathode flow channel 23, the bicarbonate solution flows out through the second cathode liquid outlet hole 22, and flows out from the first cathode liquid outlet hole 21 and the cathode liquid outlet joint 14. At the same time, after flowing through each anode flow channel 23', the potassium hydroxide solution flows out through the second anode liquid outlet hole 22', and flows out from the first anode liquid outlet hole 21' and the anode liquid outlet joint 14'.

[0074] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principle of the present invention. These improvements and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A flow channel plate, characterized in that: It comprises a plurality of parallel flow channels (100) arranged on the flow channel plate, each of the flow channels (100) comprising a plurality of smooth sections (101) and narrowing sections (102) arranged at intervals; the average width of the narrowing section (102) is smaller than the width of the smooth section (101).

2. The flow channel plate according to claim 1, characterized in that: The side wall of the narrowing section (102) is in an arc shape that bulges inwards, and the average width of the narrowing section (102) decreases step by step along the flow direction L of the gas-liquid mixture.

3. The flow channel plate according to claim 2, characterized in that: Satisfies the following formula: Wherein, B is the width of the smooth section (101); B1 is the width of the first narrowing section (102); L is the total length of the flow channel (100); and L1 is the length of one narrowing cycle.

4. The flow channel plate according to claim 3, characterized in that: The narrowing section (102) satisfies the following formula: B n =B1-nd Among them, B n is the width of the nth narrowing section (102); B1 is the width of the first narrowing section (102); and d is the degree of narrowing.

5. The flow channel plate according to claim 1 or 2, characterized in that: The number of the flow channels (100) is 8 to 15; the number of the smooth sections (101) and the number of the narrowed sections (102) are both 3 to 10.

6. A cathode structure for enhancing mass transfer, characterized in that: It comprises a cathode end plate (1), a cathode flow channel plate (2), a cathode diffusion layer (3) and an anion membrane (4) which are detachably connected in sequence; The cathode end plate (1) is provided with a first cathode liquid inlet hole (11) and a first cathode liquid outlet hole (12), and the cathode flow channel plate (2) is provided with a second cathode liquid inlet hole (21) and a second cathode liquid outlet hole (22); the first cathode liquid inlet hole (11) is connected to the second cathode liquid inlet hole (21), and the first cathode liquid outlet hole (12) is connected to the second cathode liquid outlet hole (22); The cathode flow channel plate (2) adopts the flow channel plate according to any one of claims 1 to 5, and a plurality of cathode flow channels (23) arranged in parallel are provided on the cathode flow channel plate (2), and each of the cathode flow channels (23) comprises a plurality of smooth sections (101) and narrowed sections (102) arranged at intervals; the average width of the narrowed sections (102) is smaller than the width of the smooth sections (101); A catalyst is provided on the cathode diffusion layer (3).

7. An electrolyzer for enhancing mass transfer, characterized in that: It comprises the mass transfer enhanced cathode structure as claimed in claim 6, an anode end plate (1'), an anode flow channel plate (2') and an anode diffusion layer (3'); The anode end plate (1') is provided with a first anode liquid inlet hole (11') and a first anode liquid outlet hole (12'), and the anode flow channel plate (2') is provided with a second anode liquid inlet hole (21') and a second anode liquid outlet hole (22'); the first anode liquid inlet hole (11') and the second anode liquid inlet hole (21') are in communication, and the first anode liquid outlet hole (12') and the second anode liquid outlet hole (22') are in communication; The anode flow channel plate (2') is a flow channel plate as claimed in any one of claims 1 to 5, and a plurality of anode flow channels (23') arranged in parallel are provided on the anode flow channel plate (2'); each of the anode flow channels (23') comprises a plurality of smooth sections (101) and narrowing sections (102) arranged at intervals; an average width of the narrowing section (102) is smaller than a width of the smooth section (101); A catalyst is provided on the anode diffusion layer (3').

8. The mass transfer enhanced electrolyzer according to claim 7, characterized in that: It also includes a cathode liquid inlet joint (13), an anode liquid inlet joint (13'), a cathode liquid outlet joint (14) and an anode liquid outlet joint (14'); The cathode liquid inlet joint (13) is in communication with the first cathode liquid inlet hole (11), and the anode liquid inlet joint (13') is in communication with the first anode liquid inlet hole (11'); the cathode liquid outlet joint (14) is in communication with the first cathode liquid outlet hole (12), and the anode liquid outlet joint (14') is in communication with the first anode liquid outlet hole (12').

9. The mass transfer enhanced electrolyzer according to claim 8, characterized in that: A sealing ring is provided at the connection between the first cathode liquid inlet hole (11) and the second cathode liquid inlet hole (21); and a sealing ring is provided at the connection between the first cathode liquid outlet hole (12) and the second cathode liquid outlet hole (22); A sealing ring is provided at the connection between the first anode liquid inlet hole (11') and the second anode liquid inlet hole (21'); and a sealing ring is provided at the connection between the first anode liquid outlet hole (12') and the second anode liquid outlet hole (22').

10. The mass transfer enhanced electrolyzer according to claim 9, characterized in that: The catalyst is selected from any one of a single atom catalyst, a single metal catalyst, an alloy catalyst or a catalyst composed of copper, nickel, zinc and alloys thereof.

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