Bubble separation device as well as preparation method and application thereof

Abstract

The invention provides a bubble separation device which is connected with a working electrode for producing hydrogen by electrolyzing water and is applied to separation and directional regulation and control of bubbles generated on the surface of the working electrode. The bubble separation channels are formed in the triangular areas between the adjacent through grooves, and the bubble separation channels can generate asymmetric Laplacian pressure gradients, so that bubbles are pushed to move in the specific direction. Meanwhile, the super-hydrophobic-lubricating composite coating has excellent hydrophilic property and lubricating property, not only provides a good bubble adsorption condition, but also reduces the frictional resistance of the bubbles during surface movement through a surface lubricating effect, and ensures that the bubbles can be quickly regulated and transferred in a directional manner. Hydrogen bubbles generated on the surface of the working electrode tend to move towards the surface of the super-hydrophobic-lubricating composite coating and are transferred to the bubble separation channel, and by means of asymmetry of the bubble separation channel, the hydrogen bubbles are efficiently collected to a target position through directional movement in the self-driven'movement-degenerate-removement 'circulation process.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen production by electrolysis of water, and in particular to a bubble separation device and a preparation method and application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Hydrogen is recognized as an important carrier for promoting sustainable energy transformation due to its high energy density and zero carbon emission characteristics. It is the most promising clean energy in the 21st century. Hydrogen production by water electrolysis has become an important technology in the field of hydrogen production due to its advantages such as simple operation and pure products. Water electrolysis decomposes water into hydrogen and oxygen through the cathode hydrogen evolution reaction (HER) and the anode oxygen evolution reaction (OER). However, the difficulty in controlling bubble behavior has become one of the key factors limiting the efficiency of electrolysis. During the electrolysis process, the generation and accumulation of interfacial bubbles will cover the electrode active sites, hinder the electrolyte mass transfer, and cause the local overpotential to increase, resulting in uneven current distribution. This not only aggravates the corrosion and local heating of the electrode, but also increases the heat dissipation burden and reduces the purity of hydrogen. In addition, the stress generated during the bubble desorption process may cause cracks and peeling on the electrode surface, thereby affecting the electrode life. Although the appropriate amount of bubble movement can promote convection and enhance mass transfer, the accumulation of excessive bubbles will significantly affect the local gas supersaturation, increase the solution resistance and induce polarization effects, resulting in a decrease in the overall electrolysis performance. Therefore, it is imperative to seek means to control the directional control of bubbles in the process of water electrolysis and to develop efficient bubble separation technology. Summary of the invention

[0004] In order to overcome the above problems, the present invention provides a bubble separation device and a preparation method and application thereof.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a bubble separation device, including a base plate, one end of which is provided with a plurality of connected through grooves, and the through grooves extend divergently toward the other end of the base plate; bubble separation channels are formed between adjacent through grooves, and the surface of the base plate where the bubble separation channels are located is provided with a super-hydrophobic-lubricating composite coating.

[0007] The second aspect of the present invention provides a method for preparing the bubble separation device according to the first aspect, comprising the following steps:

[0008] The bottom plate is etched with predetermined through grooves, and after washing and drying, a super-hydrophobic coating is coated on the bottom plate surface between adjacent through grooves. After drying, the entire bottom plate is immersed in a lubricating liquid, and after drying again, the bubble separation device is formed.

[0009] A third aspect of the present invention provides a system for producing hydrogen by electrolysis of water, comprising the bubble separation device described in the first aspect.

[0010] The beneficial effects of the present invention are:

[0011] (1) The present invention provides a bubble separation device, and connects it to a working electrode for hydrogen production by electrolysis of water, and is applied to the separation and directional regulation of bubbles generated on the surface of the working electrode. In the present invention, a bubble separation channel is formed by utilizing the triangular area between adjacent through grooves, and the bubble separation channel can generate an asymmetric Laplace pressure gradient, thereby driving the bubbles to move in a specific direction. At the same time, the superhydrophobic-lubricating composite coating has excellent air affinity and lubrication properties, which not only provides good bubble adsorption conditions, but also reduces the friction resistance of bubbles when moving on the surface through the surface lubrication effect, ensuring that the bubbles can quickly achieve directional regulation and transfer. The hydrogen bubbles generated on the surface of the working electrode tend to move to the surface of the superhydrophobic-lubricating composite coating and transfer to the bubble separation channel. Utilizing the asymmetry of the bubble separation channel, the directional movement is carried out through a self-driven "move-merge-re-move" cycle process and is efficiently collected to the target position.

[0012] (2) The bubble separation device provided by the present invention forms a bubble separation channel through the triangular area between adjacent through grooves, and combines the super-hydrophobic surface and the smooth low-friction characteristics to realize efficient directional control and collection of bubbles, thereby solving the problems of electrode active site coverage, electrolyte mass transfer obstruction and overpotential increase caused by bubble accumulation in the process of hydrogen production by electrolysis of water. The hydrogen production efficiency is greatly improved, the energy consumption of the electrolysis process is reduced, and an efficient and stable technical solution is provided for large-scale hydrogen production by electrolysis of water.

[0013] (3) The triangular area between adjacent through grooves forms a bubble separation channel, which significantly expands the bubble movement path and controllable area, and improves the bubble separation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0015] Figure 1 The structure diagram of the bubble separation device in the present invention; wherein 1-bottom plate, 2-through groove, 3-bubble separation channel;

[0016] Figure 2The schematic diagram of the structure of the system for producing hydrogen by electrolyzing water; wherein, 4-electrochemical workstation, 5-electrolyzer, 6-auxiliary electrode, 7-reference electrode, 8-bubble separation device, 9-electrode fixture, 10-working electrode, 11-wire.

[0017] Figure 3 is the contact angle;

[0018] Figure 4 Schematic diagram of the bubble migration process. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0020] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0021] A first typical embodiment of the present invention provides a bubble separation device, including a base plate, one end of which is provided with a plurality of connected through grooves, and the through grooves extend divergently toward the other end of the base plate; bubble separation channels are formed between adjacent through grooves, and the surface of the base plate where the bubble separation channels are located is provided with a superhydrophobic-lubricating composite coating.

[0022] In one or more embodiments, the base plate is made of polymethyl methacrylate (PMMA).

[0023] In one or more embodiments, the angle between adjacent through grooves is 2° to 8°.

[0024] In one or more embodiments, the width of the through groove is 0.5-2 mm.

[0025] In one or more embodiments, the superhydrophobic-lubricating composite coating comprises a superhydrophobic coating and a lubricating coating from bottom to top.

[0026] Preferably, the super hydrophobic coating material is nano-silicon dioxide.

[0027] Preferably, the lubricating coating material is fluorine oil or silicone oil;

[0028] The fluorine oil includes FC40 fluorinated liquid; and the silicone oil includes polydimethylsiloxane (PDMS).

[0029] A second typical embodiment of the present invention provides a method for preparing the bubble separation device according to the first aspect, comprising the following steps:

[0030] The bottom plate is etched with predetermined through grooves, and after washing and drying, a super-hydrophobic coating is coated on the bottom plate surface between adjacent through grooves. After drying, the entire bottom plate is immersed in a lubricating liquid, and after drying again, the bubble separation device is formed.

[0031] In one or more embodiments, the contact angle of the superhydrophobic coating is greater than 150°.

[0032] A third typical embodiment of the present invention provides a system for producing hydrogen by electrolyzing water, comprising the bubble separation device described in the first aspect.

[0033] Preferably, the system for producing hydrogen by electrolysis of water comprises an electrochemical workstation and an electrolytic cell, wherein an auxiliary electrode, a reference electrode and a working electrode component are placed in the electrolytic cell, wherein the working electrode component comprises a working electrode and a bubble separation device; the working electrode is connected to one end of the bubble separation device where a bubble separation channel is arranged;

[0034] Further preferably, the auxiliary electrode, reference electrode and working electrode components are all connected to the electrochemical workstation via wires.

[0035] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0036] Example 1

[0037] Figure 1 is a schematic diagram of the structure of the bubble separation device, refer to Figure 1 A bubble separation device comprises a bottom plate 1, one end of which is provided with a plurality of connected through grooves 2, and the through grooves 2 extend divergently toward the other end of the bottom plate 1; bubble separation channels 3 are formed between adjacent through grooves 2, and a super-hydrophobic-lubricating composite coating is provided on the surface of the bottom plate 1 where the bubble separation channels 3 are located.

[0038] The material of the bottom plate 1 is polymethyl methacrylate (PMMA), which is easy to process.

[0039] The angle between adjacent through grooves 2 is 2° to 8°. The angle between adjacent through grooves 2 is the angle of the bubble separation channel 3. A smaller angle can achieve a faster transport speed and a longer transport distance for the bubbles.

[0040] The width of the through groove 2 is 0.5-2 mm. The width of the through groove 2 can take into account the balance of the size of the bubble growth and the size of the carrier, which can provide sufficient bubble growth positions and control the size of the carrier.

[0041] The super-hydrophobic-lubricating composite coating includes a super-hydrophobic coating and a lubricating coating from bottom to top, wherein the super-hydrophobic coating material is nano-silicon dioxide; the lubricating coating material is fluorine oil or silicone oil, the fluorine oil is FC40 fluorinated liquid; the silicone oil is polydimethylsiloxane (PDMS).

[0042] Example 2

[0043] A polymethyl methacrylate sheet with a length of 30 mm, a width of 22 mm, and a thickness of 1 mm was placed in a CO 2 In the laser etching equipment, the polymethyl methacrylate sheet was etched to form a through groove according to the conditions set in Example 1, wherein the laser power was set to 25 W and the scanning speed was 100 mm / s. By controlling the laser power and scanning speed, the uniformity and accuracy of the microstructure were ensured to achieve the best bubble guiding effect. The etched polymethyl methacrylate sheet was first ultrasonically cleaned with a mixed solution of deionized water and anhydrous ethanol (volume ratio 1:1), each cleaning lasting 5 minutes, and repeated twice to remove the processing residues and particulate impurities on the surface.

[0044] After cleaning, place the polymethyl methacrylate sheet in a dust-free environment at 50°C for 30 minutes to dry, ensuring that the surface is completely dry. Aerosil R202 fumed silica is evenly coated on the surface of the dried polymethyl methacrylate sheet to form a uniform hydrophobic coating. After coating, place it at room temperature to cure naturally for 12 hours, and the contact angle is tested to be above 150° ( Figure 3 As shown), its super hydrophobic performance was verified. The hydrophobically modified polymethyl methacrylate sheet was immersed in fluorine oil lubricant for 3 minutes to ensure that the surface lubricant layer was completely covered. After lubrication, the polymethyl methacrylate sheet was taken out and placed in a dust-free environment to stand and air dry to obtain a bubble separation device.

[0045] Example 3

[0046] The bubble separation device prepared in Example 2 is applied to a system for producing hydrogen by electrolysis of water ( Figure 2 ), the system for producing hydrogen by electrolysis of water includes an electrochemical workstation 4 and an electrolytic cell 5, in which an auxiliary electrode 6, a reference electrode 7 and a working electrode component are placed, and the working electrode component includes a working electrode 10 and a bubble separation device 8; the working electrode 10 is connected to one end of the bubble separation device 8 where a bubble separation channel is arranged through a platinum electrode clamp; the auxiliary electrode 6, the reference electrode 7 and the working electrode component are all connected to the electrochemical workstation 4 through a wire 11.

[0047] A 5g / L KOH solution was used as the electrolyte, the open circuit voltage was set to 1.5V, and the experiment was powered by a constant voltage for 5 minutes to observe the generation, movement, desorption and collection of bubbles. The schematic diagram of the bubble movement process is shown in Figure 1. Figure 4 As shown, from Figure 4 It can be seen that bubble 1 moves toward the root of the triangle under asymmetric Laplace pressure until the position with the largest contact area stabilizes; bubble 2 continues to repeat this process and merges with bubble 1; after the merger, the bubble grows and continues to slide toward the root of the triangle under asymmetric Laplace pressure, and finally desorbs after the buoyancy exceeds the adhesion force. The experimental results show that bubbles exhibit obvious directional migration characteristics on the surface of the geometric gradient circular array, quickly moving from the vicinity of the electrode to the tip of the array where they are captured and smoothly move in a directional manner, and the migration can be completed in a few milliseconds. After the experiment, the electrolysis current was measured to be 0.006A (6mA) lower than that of the traditional device, and the energy consumption was reduced by about 18%.

[0048] Example 4

[0049] Compared with Example 3, this example adopts the same system for producing hydrogen by electrolysis of water.

[0050] A 5g / L KOH solution was used as the electrolyte, the open circuit voltage was set to 2V, and the experiment was powered by a constant voltage. The experiment lasted for 5 minutes to observe the generation, movement, desorption and collection of bubbles. The experimental results showed that the bubbles exhibited obvious directional migration characteristics on the surface of the geometric gradient circular array. They quickly moved from the vicinity of the electrode to the tip of the array where they were captured and smoothly moved in a directional manner. The migration was completed in a few milliseconds. After the experiment, the electrolysis current was measured to be 0.008A (8mA) lower than that of the traditional device, and the energy consumption was reduced by about 12.5%.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A bubble separation device, characterized in that: It comprises a bottom plate, one end of which is provided with a plurality of connected through grooves, which extend divergently toward the other end of the bottom plate; bubble separation channels are formed between adjacent through grooves, and the surface of the bottom plate where the bubble separation channels are located is provided with a super-hydrophobic-lubricating composite coating.

2. The bubble separation device according to claim 1, characterized in that: The material of the bottom plate is polymethyl methacrylate.

3. The bubble separation device according to claim 1, characterized in that: The included angle between adjacent through grooves is 2° to 8°.

4. The bubble separation device according to claim 1, characterized in that: The width of the through groove is 0.5-2 mm.

5. The bubble separation device according to claim 1, characterized in that: The super-hydrophobic-lubricating composite coating comprises a super-hydrophobic coating and a lubricating coating from bottom to top.

6. The bubble separation device according to claim 5, characterized in that: The super hydrophobic coating material is nano silicon dioxide; Alternatively, the lubricating coating material is fluorine oil or silicone oil.

7. The method for preparing the bubble separation device according to any one of claims 1 to 6, characterized in that: The steps include: The bottom plate is etched with predetermined through grooves, and after washing and drying, a super-hydrophobic coating is coated on the bottom plate surface between adjacent through grooves. After drying, the entire bottom plate is immersed in a lubricating liquid, and after drying again, the bubble separation device is formed.

8. The preparation method according to claim 7, characterized in that: The contact angle of the super hydrophobic coating is greater than 150°.

9. A system for producing hydrogen by electrolyzing water, characterized in that: It comprises the bubble separation device according to claims 1 to 6.

10. The system according to claim 9, characterized in that The system for producing hydrogen by electrolyzing water comprises an electrochemical workstation and an electrolytic cell, wherein an auxiliary electrode, a reference electrode and a working electrode component are placed in the electrolytic cell, wherein the working electrode component comprises a working electrode and a bubble separation device; the working electrode is connected to one end of the bubble separation device where a bubble separation channel is arranged; Preferably, the auxiliary electrode, reference electrode and working electrode components are all connected to the electrochemical workstation via wires.

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