A gas evolution electrode promoting bubble transfer and gas diffusion, and its preparation method and application

Abstract

The present invention discloses a gasification electrode that promotes bubble transfer and gas diffusion, and its preparation method and application. The gasification electrode includes a conductive substrate; a super-hydrophobic coating provided on the surface of the conductive substrate; the surface of the super-hydrophobic coating has an array of holes that penetrate the super-hydrophobic coating; the holes are used to generate an electrocatalytic gasification reaction and generate bubbles. Among them, the gasification electrode provided by the present invention can effectively promote the rapid transfer of bubbles and the rapid diffusion of dissolved gas molecules, thereby achieving a highly efficient electrode reaction. Taking the electrochemical hydrogen evolution reaction as an example, the gasification electrode of the present invention can control the transfer time of bubbles to within 5ms.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolytic electrodes, and more particularly to a gas evolution electrode that promotes bubble transfer and gas diffusion, and a preparation method and application thereof. Background Art

[0002] The electrocatalytic reaction that generates gas is called electrochemical gasification. Bubble adhesion and transport are challenging issues plaguing the field. For example, in the hydrogen evolution reaction (HER) from water electrolysis, conventional HER electrodes suffer from bubble adhesion and supersaturation of dissolved hydrogen. Bubble adhesion hinders direct contact between the electrode and the electrolyte, hindering the electrode reaction. Supersaturation of dissolved hydrogen in the solution can lead to concentration polarization overpotential, reducing electrolysis efficiency. Traditional methods use external force fields such as magnetic fields, mechanical stirring, or ultrasound to promote the detachment of bubbles (see: Electrochim. Acta, 2009, 54(15): 3877-83. J. Electrochem. Soc., 2007, 154(8): E112.); in recent years, the superhydrophilic / superaerophobic electrodes developed in academia (see: Angew. Chem.-Int. Edit., 2020, 59(4): 1659-65., J. Am. Chem. Soc., 2019, 141(18): 7537-43.) mainly achieve rapid detachment of bubbles by constructing micro-nanostructures on the electrode surface. The above methods can effectively solve the problem of bubble adhesion, but after the gas products detach from the electrode, they do not transfer or diffuse out of the system, but are directly released in the electrolyte, resulting in excessively high local product concentrations, which ultimately affects the electrode efficiency.

[0003] Therefore, designing an electrode structure that ensures the rapid detachment of bubbles while achieving gas transfer and diffusion is the key to further improving the electrode catalytic performance. Summary of the Invention

[0004] The first object of the present invention is to provide a gas evolution electrode that promotes bubble transfer and gas diffusion. The gas evolution electrode can promote bubble transfer and diffusion of dissolved gas molecules, thereby improving the overall catalytic efficiency of the electrode.

[0005] The second object of the present invention is to provide a method for preparing the above-mentioned gas evolution electrode.

[0006] The third object of the present invention is to provide an application of the above-mentioned gas evolution electrode in an electrochemical gas evolution reaction.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a gas evolution electrode for promoting bubble transfer and gas diffusion, wherein the gas evolution electrode comprises a conductive substrate; a super-hydrophobic coating disposed on the surface of the conductive substrate; the surface of the super-hydrophobic coating has an array of holes penetrating the super-hydrophobic coating; the holes are used to generate an electrocatalytic gas evolution reaction and generate bubbles.

[0009] The gas evolution electrode used in the electrochemical gas evolution reaction has electrocatalytic properties. It should be noted that the present invention provides a super-hydrophobic coating on the surface of the conductive substrate, and then exposes the conductive substrate through the holes, so that the electrocatalytic gas evolution reaction can occur at the exposed conductive substrate.

[0010] Furthermore, the super-hydrophobic coating communicates with the outside atmosphere, forming a uniquely structured network of gas channels. Bubbles initially form and grow within the pores. Upon contact with the super-hydrophobic coating, they are transported out of the reaction system through the gas channel network constructed by the super-hydrophobic coating. Dissolved gas molecules diffuse directly into the super-hydrophobic coating area and rapidly transfer through the gas channel network.

[0011] Preferably, the diameter of the holes is 50 micrometers to 1000 micrometers, and the distance between adjacent holes is 500 micrometers to 2000 micrometers.

[0012] Preferably, the contact angle of the super-hydrophobic coating to water droplets is 150°-180°, and the contact angle to bubbles is 0°-10°.

[0013] Preferably, at least a portion of the inner surface of the pores has a contact angle of 0°-65° for water droplets and a contact angle of 90°-180° for bubbles. It is understood that the electrode materials used in conventional electrochemical gas evolution reactions must be at least partially hydrophilic. Therefore, at least a portion of the inner surface of the pores is hydrophilic. This hydrophilicity can be derived from the exposed conductive substrate or from an additional hydrophilic layer disposed on the inner surface of the pores, such as a loaded hydrophilic catalyst.

[0014] Preferably, at least a portion of the inner surface of the pores is loaded with a hydrophilic catalyst. If the catalytic performance of the conductive substrate is poor, a catalyst with better catalytic performance can be loaded on the inner surface of the pores as needed.

[0015] Preferably, the contact angle of the hydrophilic catalyst to water droplets is 0°-65°, and the contact angle to air bubbles is 90°-180°.

[0016] In a second aspect, the present invention provides a method for preparing a gas evolution electrode that promotes bubble transfer and gas diffusion, comprising the following steps:

[0017] (1) performing super-hydrophobic modification on a conductive substrate to obtain a conductive substrate having a super-hydrophobic coating on the surface;

[0018] (2) etching away a portion of the super-hydrophobic coating so that the surface of the super-hydrophobic coating has an array of holes penetrating the super-hydrophobic coating.

[0019] Furthermore, in the above method, the preparation method further comprises loading a catalyst on the inner surface of the pores.

[0020] The step of loading the catalyst comprises: placing the conductive substrate obtained in step (2) in an electroplating solution for depositing the catalyst, and loading the catalyst on the inner surface of the pores by electroplating.

[0021] The conductive substrate is also pretreated before being superhydrophobic modified; the substrate pretreatment steps include: polishing the conductive substrate, cleaning it, removing the surface oxide layer or other pollutants by acid corrosion or alkali corrosion, cleaning, and drying.

[0022] The etching is preferably laser etching.

[0023] Exemplarily, the superhydrophobic modification includes immersing the conductive substrate in a dilute polydimethylsiloxane (PDMS) solution, taking it out, placing it in hydrophobic silica powder, and then curing and cleaning it.

[0024] In a third aspect, the present invention provides an application of a gas evolution electrode that promotes bubble transfer and gas diffusion in an electrochemical gas evolution reaction.

[0025] Preferably, during the application process, at least a portion of the super-hydrophobic coating is ensured to be in contact with the air.

[0026] Preferably, the electrolyte in the electrochemical gas evolution reaction may be acidic, neutral or alkaline.

[0027] Preferably, the electrochemical gas evolution reaction includes but is not limited to: electrochemical hydrogen evolution reaction, electrochemical oxygen evolution reaction, electrochemical nitrogen evolution reaction, electrochemical chlorine evolution reaction, etc.

[0028] It should also be noted that, unless otherwise specified, any range described herein includes the endpoints and any values therebetween, as well as any subranges formed by the endpoints or any values therebetween. The preparation methods herein are conventional methods unless otherwise specified, and the raw materials used are commercially available or prepared according to prior art.

[0029] Beneficial effects of the present invention

[0030] 1) The gas evolution electrode provided by the present invention utilizes the underwater super-hydrophobic properties of the super-hydrophobic coating to successfully construct a gas channel with a special structure composed of the super-hydrophobic coating on the electrode surface. The gas channel with this structure can effectively promote the transfer of bubbles and the rapid diffusion of dissolved gas molecules. Taking the electrochemical hydrogen evolution reaction as an example, the gas evolution electrode of the present invention can control the transfer time of a single bubble to less than 5ms.

[0031] 2) The gas evolution electrode provided by the present invention can achieve highly efficient electrode reactions. Taking the hydrogen evolution reaction of the gas evolution electrode as an example, at an overpotential of 0.4V, the current density of the gas evolution electrode of the present invention is 5 times that of the conventional electrode.

[0032] 3) The gas evolution electrode provided by the present invention is a universal electrode optimization strategy that can be applied to various electrochemical gas evolution reactions and different types of catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0034] Figure 1 The schematic diagram of the structure of the gas evolution electrode for promoting bubble transfer and gas diffusion of the present invention is shown, wherein 1 is a conductive substrate, 2 is a super-hydrophobic coating, and 3 is an array of holes.

[0035] Figure 2 The water droplet contact angle and bubble contact angle characterization diagram of the super-hydrophobic coating of the gas evolution electrode prepared in Example 2 are shown.

[0036] Figure 3 The water droplet contact angle and bubble contact angle characterization diagram of the hydrophilic catalyst supported on the gas evolution electrode prepared in Example 2 are shown.

[0037] Figure 4 A schematic diagram showing the bubble transfer process of the gas evolution electrode prepared in Example 2 during the electrochemical hydrogen evolution process is shown.

[0038] Figure 5 A schematic diagram showing the diffusion of dissolved gas molecules during electrochemical hydrogen evolution of the gas evolution electrode prepared in Example 2.

[0039] Figure 6 High-speed video footage of bubble transfer and transport during electrochemical hydrogen evolution of the gas evolution electrode prepared in Example 1 is shown.

[0040] Figure 7 A schematic diagram showing the bubble adhesion phenomenon of the gas evolution electrode prepared in Comparative Example 1 during the electrochemical hydrogen evolution process is shown.

[0041] Figure 8 The graphs showing the change of current density versus electrode potential corresponding to the gas evolution electrodes prepared in Example 2 and Comparative Example 2 are shown.

[0042] Figure 9 A schematic diagram showing the simulation of the hydrogen concentration distribution of hydrogen molecules at the electrode interface during the electrochemical hydrogen evolution process of the gas evolution electrodes prepared in Example 2 and Comparative Example 2 is shown; wherein, Figure 9 a) shows a schematic diagram of the simulation of the hydrogen concentration distribution of hydrogen molecules at the electrode interface during the electrochemical hydrogen evolution process of the gas evolution electrode prepared in Example 2, Figure 9 b) shows a schematic diagram of the simulation of the hydrogen concentration distribution of hydrogen molecules at the electrode interface during the electrochemical hydrogen evolution process of the gas evolution electrode prepared in Comparative Example 2.

[0043] Figure 10 High-speed video images of bubble transfer and transport during electrochemical hydrogen evolution of the aerophilic / aerophobic synergistic stripe array electrode prepared in Comparative Example 3 are shown.

[0044] Figure 11 A schematic diagram showing the simulation of the hydrogen concentration distribution of hydrogen molecules at the electrode interface during the electrochemical hydrogen evolution process of the aerophilic / aerophobic cooperative stripe array electrode prepared in Comparative Example 3 is shown.

[0045] Figure 12 A curve diagram showing the change in current density versus electrode potential corresponding to the air-philic / air-phobic cooperative stripe array electrode prepared in Comparative Example 3 is shown. DETAILED DESCRIPTION

[0046] The present invention is described in detail below through examples. It is necessary to point out that these examples are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Those skilled in the art may make non-essential improvements and adjustments based on the above invention. The embodiments of the present invention and the features of the embodiments may be combined with each other unless there is a conflict.

[0047] Example 1

[0048] Preparation of a gas evolution electrode that promotes bubble transfer and gas diffusion includes the following steps:

[0049] (1) Substrate pretreatment: The surface of a 1.5 cm*1.5 cm*0.5 mm platinum sheet was polished with 500# sandpaper. The polished platinum sheet was ultrasonically cleaned in an ethanol solution, dried at room temperature, and then soaked in concentrated nitric acid for about 5 min. The sheet was ultrasonically washed with deionized water and then set aside. The contact angle of the pretreated platinum sheet substrate to water droplets was measured to be 40°, and the contact angle to bubbles was 120°.

[0050] (2) Superhydrophobic modification: The platinum sheet substrate pretreated in step (1) is immersed in a dilute polydimethylsiloxane (PDMS) solution diluted with n-hexane. After being taken out and left to air at room temperature for 2-3 minutes, the whole substrate is placed in hydrophobic silica powder. Under the adhesive effect of PDMS, the hydrophobic silica adheres to the substrate. After curing at 80°C for 2 hours, the excess silica powder is rinsed off with ethanol. After the ethanol evaporates, a platinum sheet covered with a superhydrophobic coating is obtained; wherein, the contact angle of water droplets on the superhydrophobic coating is 155°, and the contact angle of bubbles on the superhydrophobic coating is approximately zero.

[0051] (3) Laser etching: A femtosecond laser is used to etch an array of points on a platinum substrate covered with a super-hydrophobic coating. The marking power is 200 W, the laser frequency is 0.1 MHz, and the scanning speed is 300 mm / s. Ten times of marking can completely etch away the super-hydrophobic coating at the array, forming an array of holes that penetrate the super-hydrophobic coating and expose the platinum substrate. The diameter of the holes is 500 μm, and the spacing between adjacent holes is 1.5 mm.

[0052] Example 2

[0053] Preparation of a gas evolution electrode that promotes bubble transfer and gas diffusion includes the following steps:

[0054] (1) Substrate pretreatment: The surface of a 1.5 cm*1.5 cm*0.5 mm titanium sheet was polished with 500# sandpaper. The polished platinum sheet was ultrasonically cleaned in an ethanol solution. After drying at room temperature, it was immersed in a 10 wt% oxalic acid solution and treated at 90°C for 1 h. After that, it was taken out and ultrasonically washed with deionized water and ethanol several times in sequence. It was dried and set aside.

[0055] (2) Superhydrophobic modification: The titanium substrate pretreated in step (1) is immersed in a dilute polydimethylsiloxane (PDMS) solution diluted with n-hexane. After being removed and left to air at room temperature for 2-3 minutes, the entire substrate is placed in hydrophobic silica powder. Under the adhesive action of PDMS, the hydrophobic silica adheres to the substrate. After curing at 80°C for 2 hours, the titanium substrate is removed and rinsed with ethanol to remove excess silica powder. After the ethanol evaporates, a superhydrophobic coating is obtained.

[0056] (3) Laser etching: A femtosecond laser is used to etch an array of points on a platinum substrate covered with a super-hydrophobic coating. The marking power is 200 W, the laser frequency is 0.1 MHz, and the scanning speed is 300 mm / s. Ten times of marking can completely etch away the super-hydrophobic coating at the array, forming an array of holes that penetrate the super-hydrophobic coating and expose the titanium substrate. The diameter of the holes is 500 μm, and the spacing between adjacent holes is 1.5 mm.

[0057] (4) Loading hydrophilic catalyst: Place the titanium sheet obtained in step (3) in an electroplating solution (3mM H2PtCl6, 100mM KNO3). Set the potential to -0.05V and electroplating for 1 hour (Ag / AgCl is used as the reference electrode). Finally, the platinum catalyst is loaded in the array area of the holes to obtain a gas evolution electrode (its structural schematic is shown in FIG). Figure 1 ); wherein, the contact angle of water droplets on the super-hydrophobic coating is measured to be 155°, and the contact angle of bubbles on the super-hydrophobic coating is approximately zero (e.g. Figure 2 The contact angle of the supported platinum catalyst to water droplets is 30°, and the contact angle to bubbles is 158° (as shown in FIG. Figure 3 shown).

[0058] Comparative Example 1

[0059] Preparation of a gas evolution platinum electrode, comprising the following steps:

[0060] The surface of a 1.5cm*1.5cm*0.5mm platinum sheet was polished with 500# sandpaper. The polished platinum sheet was ultrasonically cleaned in an ethanol solution, dried at room temperature, and then soaked in concentrated nitric acid for about 5 minutes. It was then ultrasonically washed multiple times with deionized water and ethanol in sequence, dried, and set aside. The contact angle of the gas-evolving platinum electrode for water droplets was measured to be 40°, and the contact angle for bubbles was 120°.

[0061] Comparative Example 2

[0062] Preparation of a nano-platinum gas evolution electrode comprises the following steps:

[0063] (1) Substrate pretreatment: The surface of a 1.5 cm*1.5 cm*0.5 mm titanium sheet was polished with 500# sandpaper. The polished platinum sheet was ultrasonically cleaned in an ethanol solution. After drying at room temperature, it was immersed in a 10 wt% oxalic acid solution and treated at 90°C for 1 h. After that, it was taken out and ultrasonically washed with deionized water and ethanol several times in sequence. It was dried and set aside.

[0064] (2) Loading a hydrophilic catalyst: The smooth titanium sheet prepared in step (1) was placed in an electrodeposition solution (3 mM H2PtCl6, 100 mM KNO3). Electrodeposition was performed at a potential of -0.05 V for 1 hour (Ag / AgCl was used as a reference electrode) to obtain a nano-platinum gas evolution electrode. The contact angle of the loaded platinum catalyst for water droplets was measured to be 30°, and the contact angle for air bubbles was measured to be 158°.

[0065] Comparative Example 3

[0066] Preparation of an aerophilic / aerophobic synergistic stripe array electrode comprises the following steps:

[0067] (1) Substrate pretreatment: The surface of a 1.5 cm*1.5 cm*0.5 mm titanium sheet was polished with 500# sandpaper. The polished platinum sheet was ultrasonically cleaned in an ethanol solution. After drying at room temperature, it was immersed in a 10 wt% oxalic acid solution and treated at 90°C for 1 h. After removal, it was ultrasonically cleaned with deionized water and ethanol several times in sequence, and dried for later use.

[0068] (2) Mask attachment: The PET film is attached to the pre-treated titanium sheet as a whole, and the PET film is cut into stripes for use as a mask by laser cutting. The stripe width and spacing are both 500 μm, and a titanium sheet with a stripe mask attached is obtained;

[0069] (3) Superhydrophobic modification: The titanium sheet with the striped mask prepared in step (2) is immersed in a dilute polydimethylsiloxane (PDMS) solution diluted with n-hexane. After being removed and left to air at room temperature for 2-3 minutes, the titanium sheet is placed in hydrophobic silica powder. Under the adhesive action of PDMS, the hydrophobic silica adheres to the substrate. The titanium sheet is cured at 80°C for 2 hours. After removal, the excess silica powder is rinsed with ethanol. After the ethanol evaporates, the mask is removed to obtain a titanium sheet with superhydrophobic stripes.

[0070] (4) Hydrophilic catalyst loading: The titanium sheet with the super-hydrophobic stripe array prepared in step (3) was placed in an electrodeposition solution (3 mM H2PtCl6, 100 mM KNO3). The electrodeposition was performed at a potential of -0.05 V for 1 hour (Ag / AgCl was used as a reference electrode). Finally, a platinum catalyst was loaded on the laser-etched array area to obtain an aerophilic / aerophobic synergistic stripe array electrode. The contact angle of a water droplet on the super-hydrophobic stripe was measured to be 155°, while the contact angle of an air bubble on the super-hydrophobic stripe was approximately zero. The contact angle of the loaded platinum catalyst on a water droplet was 30°, and on an air bubble was 158°.

[0071] Test Example 1

[0072] Electrochemical test: The gas evolution electrode of Example 1 and the gas evolution platinum electrode of Comparative Example 1 were fixed with polytetrafluoroethylene electrode clamps, and electrochemical hydrogen evolution reaction was carried out in 0.5M sulfuric acid at a potential of -0.3V (reversible hydrogen electrode RHE was used as reference). The hydrogen evolution process of the electrode was observed in situ with a high-speed camera. The results are as follows: Figure 6-7 shown.

[0073] Depend on Figure 6 It can be seen that in the electrochemical hydrogen evolution reaction of the gas evolution electrode in Example 1, the bubbles generated are first generated on the exposed platinum substrate. When the bubbles grow and contact the superhydrophobic coating, the bubbles are quickly captured and transferred to the outside of the reaction system through the superhydrophobic coating area, and the transfer time of a single bubble is about 3ms.

[0074] Depend on Figure 7 It can be seen that in the electrochemical hydrogen evolution reaction of the gas evolution electrode of Comparative Example 1 and Comparative Example 3, the bubbles generated continue to adhere to the electrode surface and cannot be transferred in time.

[0075] Test Example 2

[0076] Electrochemical test: The gas evolution electrode of Example 2 and the nano-platinum gas evolution electrode of Comparative Example 2 were fixed with polytetrafluoroethylene electrode clamps, and electrochemical hydrogen evolution tests were performed using linear sweep voltammetry in 0.5M sulfuric acid. The curves of current density versus electrode potential are shown in Figure 2. Figure 8 As shown, the electrochemical hydrogen evolution reaction was carried out at a potential of -0.3 V (reversible hydrogen electrode RHE as reference), and the electrode hydrogen evolution process was observed in situ using a high-speed camera.

[0077] In-situ observation with a high-speed camera revealed that the gas evolution electrode prepared in Example 2 was used for electrochemical hydrogen evolution, and the transfer time of a single bubble was approximately 3 ms.

[0078] The schematic diagram of the bubble transfer process of the gas evolution electrode prepared in Example 2 during the electrochemical hydrogen evolution process is shown in FIG. Figure 4 As shown: During the electrochemical hydrogen evolution process, bubbles are first generated in the hydrophilic catalyst area. After contacting the superhydrophobic coating, the bubbles merge with the air film on the surface of the superhydrophobic coating and are transferred away.

[0079] The schematic diagram of the bubble transfer process of the gas evolution electrode prepared in Example 2 during the electrochemical hydrogen evolution process is shown in FIG. Figure 5 As shown in the figure: During the electrochemical hydrogen evolution process, dissolved gas molecules are enriched near the interface between the bubbles and the hydrophilic catalyst. Gas channels exist on the superhydrophobic coating, connecting to the atmosphere, and the gas concentration is approximately zero. Therefore, dissolved gas molecules can diffuse from the high-concentration electrode surface to the low-concentration gas channels due to the concentration gradient, achieving rapid transfer of gas molecules.

[0080] Depend on Figure 8 It can be seen that at an overpotential of 0.4 V, the current density of the gas evolution electrode of Example 2 is nearly 1000 mA / cm 2 , while the current density of the nano-platinum gas evolution electrode in Comparative Example 2 is about 200 mA / cm 2 .

[0081] Test Example 3

[0082] (1) Comsol constructed an electrolytic water diffusion model for the gas evolution electrode prepared in Example 2. The area with a radius of 250 μm in the center of the model was the electrode, and the area surrounding the electrode was a superhydrophobic area. The electrolysis potential was set to -1.4 V (two-electrode system), the hydrogen ion concentration in the electrolyte was set to 1 M (equivalent to 0.5 M sulfuric acid), and the initial concentration of hydrogen molecules was set to zero.

[0083] (2) Comsol constructed a water electrolysis diffusion model for the nano-platinum gas evolution electrode prepared in Comparative Example 2. The electrode was located in the center of the model with a radius of 250 μm, and no superhydrophobic region was set around the electrode. The electrolysis potential was set to -1.4 V (two-electrode system), the hydrogen ion concentration in the electrolyte was set to 1 M (equivalent to 0.5 M sulfuric acid), and the initial concentration of hydrogen molecules was set to zero.

[0084] Results: Taking into account the electrode reaction and the diffusion of dilute species, the concentration distribution of hydrogen molecules around the electrode was obtained through finite element simulation. Figure 9 As shown, the calculated maximum hydrogen concentration on the surface of the gas evolution electrode of Example 2 is about 0.03M; the maximum hydrogen concentration on the surface of the nano-platinum gas evolution electrode of Comparative Example 2 is about 0.06M, which is more serious than that of Example 2 in that hydrogen molecules are enriched on the electrode surface.

[0085] Test Example 4

[0086] The gas-philic / gas-phobic synergistic stripe array electrode of Comparative Example 3 was fixed with a polytetrafluoroethylene electrode clamp in 0.5M sulfuric acid, and electrochemical hydrogen evolution reaction was carried out at a potential of -0.3V (reversible hydrogen electrode RHE was used as a reference), and the hydrogen evolution process of the electrode was observed in situ with a high-speed camera. Figure 10 shown.

[0087] Depend on Figure 10 As can be seen, bubbles generated by the electrochemical hydrogen evolution reaction first form at the platinum catalyst. When the bubbles grow and contact the superhydrophobic area, they are quickly captured and transferred out of the reaction system through the superhydrophobic area. The transfer time of a single bubble is about 8ms, which is longer than that of Examples 1-2.

[0088] Test Example 5

[0089] Comsol constructed a water electrolysis diffusion model for the aerophilic / aerophobic synergistic stripe array electrode of Comparative Example 3. The 500μm-wide region in the center of the model served as the electrode, while the surrounding area was a superhydrophobic region. The electrolysis potential was set at -1.4V (two-electrode system), the hydrogen ion concentration in the electrolyte was set to 1M (equivalent to 0.5M sulfuric acid), and the initial concentration of hydrogen molecules was set to zero.

[0090] Taking into account the electrode reaction and the diffusion of dilute material concentration, the concentration distribution of hydrogen molecules around the electrode is obtained through finite element simulation. Figure 11 As shown, the maximum concentration of hydrogen on the electrode surface is about 0.07M, which is more serious than that in Example 2 in that hydrogen molecules are enriched on the electrode surface.

[0091] Test Example 6

[0092] The gas-philic / gas-phobic synergistic stripe array electrode of Comparative Example 3 was fixed with a polytetrafluoroethylene electrode clamp in 0.5 M sulfuric acid, and electrochemical hydrogen evolution test was performed using linear sweep voltammetry. The curve of current density versus electrode potential is shown in FIG. Figure 12 shown.

[0093] Depend on Figure 12 It can be seen that the electrode performance of the air-philic / air-phobic cooperative stripe array electrode of Comparative Example 3 is not as good as that of Example 2.

[0094] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A gas evolution electrode that promotes bubble transfer and gas diffusion, characterized in that: The invention comprises a conductive substrate (1); a super-hydrophobic coating (2) provided on the surface of the conductive substrate; the surface of the super-hydrophobic coating has an array of holes (3) penetrating the super-hydrophobic coating; the holes are used to generate an electrocatalytic gas evolution reaction and generate bubbles; The diameter of the holes is 50 microns to 1000 microns, and the distance between adjacent holes is 500 microns to 2000 microns; The contact angle of the super-hydrophobic coating to water droplets is 150°-180°, and the contact angle to bubbles is 0°-10°; At least a portion of the inner surface of the hole has a contact angle of 0°-65° for water droplets and a contact angle of 90°-180° for bubbles; The gas evolution electrode is prepared according to the following steps: (1) performing superhydrophobic modification on a conductive substrate to obtain a conductive substrate having a superhydrophobic coating on the surface; (2) etching away a portion of the super-hydrophobic coating so that the surface of the super-hydrophobic coating has an array of holes penetrating the super-hydrophobic coating.

2. The gas evolution electrode according to claim 1, characterized in that The inner surface of the pores is at least partially loaded with a hydrophilic catalyst.

3. The gas evolution electrode according to claim 2, characterized in that The contact angle of the hydrophilic catalyst to water droplets is 0°-65°, and the contact angle to air bubbles is 90°-180°.

4. A method for preparing a gas evolution electrode according to any one of claims 1 to 3, characterized in that: The steps include: (1) performing superhydrophobic modification on a conductive substrate to obtain a conductive substrate having a superhydrophobic coating on the surface; (2) etching away a portion of the super-hydrophobic coating so that the surface of the super-hydrophobic coating has an array of holes penetrating the super-hydrophobic coating.

5. The preparation method according to claim 4, characterized in that The preparation method further comprises loading a catalyst on the inner surface of the pores.

6. The preparation method according to claim 5, characterized in that The step of loading the catalyst comprises placing the conductive substrate obtained in step (2) in an electroplating solution for depositing the catalyst, and loading the catalyst on the inner surface of the pores by electroplating.

7. The preparation method according to claim 4, characterized in that The conductive substrate is also pretreated before being superhydrophobic modified; the substrate pretreatment steps include: polishing the conductive substrate, cleaning it, removing the surface oxide layer or other pollutants by acid corrosion or alkali corrosion, cleaning, and drying.

8. Use of the gas evolution electrode according to any one of claims 1 to 3 in an electrochemical gas evolution reaction, characterized in that: At least a portion of the super-hydrophobic coating is ensured to be in contact with air.

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