A gas-liquid split micro-nano porous electrode device

Abstract

This invention discloses a gas-liquid split-flow micro / nano porous electrode device, comprising a U-shaped hollow substrate and a multi-level micro / nano pore directional flow channel system disposed on its wall. The directional flow channel system is divided into a nitrogen transport channel group on the inner wall side and an electrolyte transport channel group on the outer wall side. Both groups of channels are composed of several micropore arrays arranged in a staggered manner along the substrate wall thickness direction. The nitrogen transport channel group adopts a gradually expanding structure, allowing nitrogen to enter from the small-diameter end on the N2 main inlet pressure stabilizing chamber side and exit from the large-diameter end on the inner wall catalyst layer side, achieving directional enrichment and efficient transport of nitrogen. The electrolyte transport channel group adopts a gradually contracting structure, allowing the electrolyte to enter from the large-diameter end on the external environment side and exit from the small-diameter end on the inner wall catalyst layer side, suppressing excessive proton transport to the catalyst layer interface. This invention, through spatial isolation and independent control, simultaneously solves the problems of limited nitrogen mass transfer and severe hydrogen evolution side reactions in traditional electrodes, significantly improving ammonia yield and Faraday efficiency.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic electrode technology, specifically relating to a gas-liquid split micro / nano porous electrode device. Background Technology

[0002] Electrocatalytic nitrogen reduction for ammonia synthesis can be carried out at room temperature and pressure with the help of a catalyst driven by renewable energy. Moreover, the raw materials nitrogen and water are abundant, making it hailed as the most promising ammonia synthesis strategy. However, this technology has many problems that restrict its development: (1) Nitrogen itself is too stable and difficult to activate, becoming the rate-determining step of the reaction and reducing the overall reaction rate. (2) Nitrogen has extremely low solubility in aqueous electrolytes, resulting in extremely low nitrogen concentration at the reaction interface, leading to a "reaction gas starvation" phenomenon, which greatly weakens the ammonia yield of the system. (3) Within the potential range of the nitrogen reduction reaction, the hydrogen evolution reaction of protons at the interface in the electrolyte will compete for electrons. Once the catalyst surface is exposed to the nitrogen-depleted electrolyte, the protons in the electrolyte will quickly occupy the active sites, forming hydrogen as a byproduct, which leads to a decrease in Faraday efficiency.

[0003] To address these issues, researchers have attempted to introduce gas diffusion electrodes (such as carbon paper, carbon cloth, and metal foam) to provide nitrogen transport channels using their porous structures. While these electrodes have been applied on a large scale, existing gas diffusion electrodes have significant drawbacks: their simple internal pore structure allows only passive diffusion of the gas phase, preventing active control of nitrogen transport to the catalyst layer; they also lack selective inhibition of proton transport in the electrolyte, resulting in disordered competition between the gas and liquid phases at the catalyst layer interface, making it difficult to simultaneously meet the dual requirements of high nitrogen supply and low proton permeation. Therefore, a gas-liquid independent control electrode structure is urgently needed to simultaneously address the problems of insufficient reactant supply and competition from side reactions at the mass transfer level. Summary of the Invention

[0004] This invention proposes a gas-liquid split micro / nano porous electrode device, which achieves directional enrichment of nitrogen and suppression of proton transport through a U-shaped hollow matrix and misaligned channels on the inner and outer walls, simultaneously solving the problems of limited mass transfer and hydrogen evolution competition in ammonia synthesis.

[0005] This invention provides a gas-liquid splitting micro / nano porous electrode device, the electrode device comprising a U-shaped hollow substrate;

[0006] The system comprises a multi-level micro-nano pore directional flow channel system disposed on the wall of the U-shaped hollow matrix. The multi-level micro-nano pore directional flow channel system is divided into a nitrogen transport channel group on the inner wall side and an electrolyte transport channel group on the outer wall side. The nitrogen transport channel group is connected to the N2 main inlet pressure stabilizing cavity inside the U-shaped hollow matrix and the inner wall catalyst layer side of the U-shaped hollow matrix. The electrolyte transport channel group is connected to the external electrolyte environment and the inner wall catalyst layer side of the U-shaped hollow matrix. Both the nitrogen transport channel group and the electrolyte transport channel group are composed of several micropore arrays with different structures and porosities. The nitrogen transport channel group and the electrolyte transport channel group are staggered in the matrix wall thickness direction to form a gas-liquid split directional transport flow field system.

[0007] Preferably, the micro-nano channels in the nitrogen transport channel assembly have a gradually expanding structure, with nitrogen entering from the small-diameter end facing the N2 main inlet pressure stabilizing cavity and exiting from the large-diameter end facing the inner wall catalyst layer, thereby achieving directional enrichment and efficient transport of nitrogen at the catalyst layer interface; the micro-nano channels in the electrolyte transport channel assembly have a gradually contracting structure, with electrolyte entering from the large-diameter end facing the external electrolyte environment and exiting from the small-diameter end facing the inner wall catalyst layer, thereby achieving selective permeation control of protons from the electrolyte to the catalyst layer interface.

[0008] Preferably, the substrate of the U-shaped hollow matrix is ​​a metal-based material such as nickel-based, iron-based, or titanium alloy, or a carbon-based material.

[0009] Preferably, the electrode device is fabricated using micro / nano fabrication, precision CNC machining, or ion etching processes.

[0010] Preferably, the inlet end of the nitrogen gas transmission channel group is located on the inner wall side of the U-shaped hollow substrate, facing the main N2 gas intake and stabilizing cavity, and the outlet end is located on the inner wall catalytic layer side of the U-shaped hollow substrate. The diameter of the inlet end is smaller than that of the outlet end. The liquid inlet end of the electrolyte transmission channel group is located on the outer wall side of the U-shaped hollow substrate, facing the external electrolyte environment, and the outlet end is located on the inner wall catalytic layer side of the U-shaped hollow substrate. The diameter of the inlet end is larger than that of the outlet end.

[0011] Preferably, the flow field structure of the multi-level micro / nano-channel directional flow system is any one of a circular flow field, an S-shaped flow field, or an L-shaped flow field.

[0012] Preferably, when the flow field structure is a circular flow field, the air inlet of the nitrogen transmission channel group is a coaxial and concentric frustum-shaped air inlet, and the liquid inlet of the electrolyte transmission channel group is a coaxial and concentric frustum-shaped liquid inlet; when the flow field structure is an S-shaped flow field, the air inlet is an S-shaped air inlet, and the liquid inlet is an S-shaped liquid inlet; when the flow field structure is an L-shaped flow field, the air inlet is an L-shaped air inlet, and the liquid inlet is an L-shaped liquid inlet.

[0013] Preferably, the through holes in the nitrogen gas transmission channel group and the through holes in the electrolyte transmission channel group are arranged in an equally spaced square array, with a center-to-center distance of 1-3 mm between adjacent through holes, and the through holes are uniformly distributed on the wall of the U-shaped hollow substrate; the misalignment of the through holes in the nitrogen gas transmission channel group and the through holes in the electrolyte transmission channel group in the thickness direction of the substrate wall is 0.5-2 mm.

[0014] Preferably, the inner wall thickness of the U-shaped hollow matrix is ​​2-4 mm, and the outer wall thickness is 1-3 mm; the overall length of the U-shaped hollow matrix ranges from 10-100 mm, the width ranges from 10-100 mm, and the height ranges from 20-200 mm; the inner diameter of the N2 main intake pressure stabilizing cavity ranges from 8-96 mm.

[0015] This invention also provides the application of gas-liquid splitting micro / nano porous electrode devices in aqueous electrochemical ammonia synthesis.

[0016] One or more technical solutions provided in the embodiments of this application have at least the following technical effects:

[0017] 1. This invention spatially isolates the main nitrogen channel from the electrolyte environment through a U-shaped hollow structure, constructing an independent gas-phase transport cavity to avoid mutual interference between the gas and liquid phases before entering the catalyst layer. The gradually expanding structure of the inner wall nitrogen transport channel group utilizes the principle of fluid expansion to reduce the nitrogen flow rate and create a micro-positive pressure zone, achieving directional enrichment and long-term residence of nitrogen at the catalyst layer interface, effectively alleviating "reactant gas starvation" and improving reactant utilization. The gradually contracting structure of the outer wall electrolyte transport channel group increases proton mass transfer resistance through channel contraction, suppressing hydrogen evolution side reactions and allowing more electrons to be used for the generation of the target product, ammonia, significantly improving Faraday efficiency.

[0018] 2. This invention employs a gas-liquid channel staggered arrangement structure to construct a micro-ordered three-phase reaction network inside the catalyst layer, maximizing the gas-liquid-solid interface area and avoiding the waste of active sites caused by disordered competition between the gas and liquid phases in traditional electrodes, thereby further improving the reaction rate and selectivity.

[0019] 3. Starting from mass transfer regulation, this invention solves two key problems at the same time: insufficient nitrogen supply and competition for hydrogen evolution, providing a brand-new electrode solution for efficient electrocatalytic ammonia synthesis. Attached Figure Description

[0020] Figure 1 This is a cross-sectional schematic diagram of the gas-liquid splitting micro / nano porous electrode device of Embodiment 1 of the present invention;

[0021] Figure 2 This is a front view schematic diagram of the gas-liquid splitting micro / nano porous electrode device of Embodiment 1 of the present invention;

[0022] Figure 3 This is a top view schematic diagram of the gas-liquid splitting micro / nano porous electrode device of Embodiment 1 of the present invention;

[0023] Figure 4 This is a schematic diagram of the internal micropore structure of the gas-liquid splitting micro / nano porous electrode device of Embodiment 1 of the present invention.

[0024] Figure 5 This is a cross-sectional schematic diagram of the gas-liquid splitting micro / nano porous electrode device of Embodiment 2 of the present invention;

[0025] Figure 6 This is a front view schematic diagram of the gas-liquid splitting micro / nano porous electrode device of Embodiment 2 of the present invention;

[0026] Figure 7 This is a top view schematic diagram of the gas-liquid splitting micro / nano porous electrode device of Embodiment 2 of the present invention;

[0027] Figure 8 This is a schematic diagram of the internal micropore structure of the gas-liquid splitting micro / nano porous electrode device of Embodiment 2 of the present invention;

[0028] Figure 9 This is a cross-sectional schematic diagram of the gas-liquid splitting micro / nano porous electrode device of Embodiment 3 of the present invention;

[0029] Figure 10 This is a front view schematic diagram of the gas-liquid splitting micro / nano porous electrode device of Embodiment 3 of the present invention;

[0030] Figure 11 This is a top view schematic diagram of the gas-liquid splitting micro / nano porous electrode device of Embodiment 3 of the present invention;

[0031] Figure 12 This is a schematic diagram of the internal micropore structure of the gas-liquid splitting micro / nano porous electrode device of Embodiment 3 of the present invention.

[0032] Among them, a1-first gas-liquid splitting micro-nano porous electrode device, b1-first circular air inlet, c1-first frustum-shaped main air inlet channel, d1-first circular air outlet, e1-first circular liquid inlet, f1-first frustum-shaped main liquid inlet channel, g1-first circular liquid outlet, h1-first N2 main air inlet pressure stabilizing cavity; a2-second gas-liquid splitting micro-nano porous electrode device, b2-second S-shaped air inlet, c2-second S-shaped main air inlet channel, d2-second S-shaped main air inlet channel, e1-first circular liquid outlet ... e2-second gas-liquid splitting micro-nano porous electrode device, b2-second S-shaped air inlet, c2-second S-shaped main air inlet channel, d2-second S-shaped main air inlet channel, e1-first circular liquid outlet, f1-first circular liquid outlet, g1-first circular liquid outlet, h1-first N2 main air inlet pressure stabilizing cavity; e2-second gas-liquid splitting micro-nano porous electrode device, b2-second S-shaped air inlet, c2-second S-shaped main air inlet channel, g1-first circular liquid outlet, h1-first N2 main air inlet pressure stabilizing cavity, e1-first circular liquid outlet, f1-first circular liquid outlet, g1-first circular liquid outlet, h1-first N2 main E2 - Second S-shaped air outlet, f2 - Second S-shaped liquid inlet, g2 - Second S-shaped liquid main channel, h2 - Second N2 main air inlet pressure stabilizing cavity; a3 - Third gas-liquid splitting micro-nano porous electrode device, b3 - Third L-shaped air inlet, c3 - Third L-shaped liquid main channel, d3 - Third L-shaped air outlet, e3 - Third L-shaped liquid inlet, f3 - Third L-shaped liquid main channel, g3 - Third L-shaped liquid outlet, h3 - Third N2 main air inlet pressure stabilizing cavity. Detailed Implementation

[0033] This application addresses the critical challenges of limited nitrogen mass transfer and severe hydrogen evolution side reactions in electrocatalytic ammonia synthesis by proposing a gas-liquid split-flow micro / nano porous electrode device. The core idea is to use a U-shaped hollow substrate as the main nitrogen channel, spatially isolating it from the external electrolyte environment. An inner wall nitrogen flow channel (gradually expanding structure, small-diameter inlet, large-diameter outlet) and an outer wall electrolyte flow channel (gradually contracting structure, large-diameter inlet, small-diameter outlet) are respectively set on the substrate wall, enabling independent control of the gas and liquid phases. Furthermore, the gas and liquid channels are staggered along the wall thickness direction, constructing a micro-ordered three-phase reaction network within the catalytic layer. Through the synergistic effect of the above structure, the problems of insufficient nitrogen supply and hydrogen evolution competition are simultaneously solved at the mass transfer level, significantly improving ammonia yield and Faraday efficiency, providing a novel electrode solution for electrocatalytic nitrogen reduction ammonia synthesis.

[0034] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0035] In this embodiment, the substrate of the U-shaped hollow matrix is ​​a metal-based material such as nickel-based, iron-based, or titanium alloy, or a carbon-based material; the electrode device is prepared by micro-nano processing, precision CNC machining, or ion etching process.

[0036] Example 1

[0037] This embodiment provides a gas-liquid splitting micro / nano porous electrode device with a circular flow field structure, the structure of which is as follows: Figures 1-4 As shown.

[0038] The circular gas-liquid splitting micro / nano porous electrode device includes a first gas-liquid splitting micro / nano porous electrode device a1, which uses a U-shaped hollow iron-group metal substrate as a supporting base plate, and the internal hollow region is the first N2 main intake pressure stabilizing cavity h1. The substrate wall is divided into an inner wall and an outer wall, with an inner wall thickness of 3 mm and an outer wall thickness of 2 mm.

[0039] The inner wall of the substrate is provided with a nitrogen transmission channel assembly, which consists of an array of several coaxial and concentric frustum-shaped air inlets. Specifically, the frustum-shaped air inlets include a first circular air inlet b1, a first frustum-shaped main air inlet channel c1, and a first circular air outlet d1.

[0040] The first circular air inlet b1 is located on the inner wall of the substrate, facing the N2 main air intake and pressure stabilization cavity inside the device. It is a small-diameter end with a single-hole flow area of ​​0.8 mm². 2 The corresponding aperture is φ1.0 mm. The first circular air inlet b1 serves as the air inlet opening of the first frustum-shaped main air intake channel c1.

[0041] The first circular outlet d1 is located on the inner wall of the substrate, on the side of the catalyst layer. It is the large-diameter end, with an effective mass transfer area of ​​3.1 mm per pore. 2 The corresponding aperture is φ2.0 mm. The first circular air outlet d1 serves as the air outlet opening of the first frustum-shaped main air intake channel c1.

[0042] The first frustum-shaped main air intake channel c1 is a coaxial and concentric frustum-shaped through hole. Its diameter gradually increases from the first circular air inlet b1 to the first circular air outlet d1, completely penetrating the 3 mm thick inner wall of the substrate. The total length of the channel is the same as the thickness of the inner wall, which is 3 mm. The side wall taper is 81°, and both ends are coaxially connected to the first circular air inlet b1 and the first circular air outlet d1, respectively.

[0043] Nitrogen gas enters from the N2 main intake pressure stabilizing chamber h1 through the first circular inlet b1 and exits from the first circular outlet d1. The flow direction is from the small inlet to the large inlet (gradual expansion flow), realizing the directional enrichment and transport of nitrogen gas.

[0044] The outer wall of the substrate is provided with an electrolyte transport channel assembly, which consists of an array of several coaxial and concentric frustum-shaped liquid inlet holes. Specifically, the frustum-shaped liquid inlet holes include a first circular liquid inlet e1, a first frustum-shaped liquid inlet main channel f1, and a first circular liquid outlet g1.

[0045] The first circular inlet e1 is located on the outer wall of the substrate, facing the external electrolyte environment. It is the large-diameter end, with a single-hole flow area of ​​7.1 mm². 2 The corresponding orifice diameter is φ3 mm. It serves as the inlet opening of the first frustum-shaped liquid inlet channel f1.

[0046] The first circular outlet g1 is located on the inner wall of the substrate, on the side of the catalyst layer. It is the small-diameter end, with a single pore diameter of φ1.6mm (small opening) and an effective mass transfer area of ​​2.0 mm². 2 The outlet opening serves as the main inlet channel f1 of the first frustum-shaped structure.

[0047] The first frustum-shaped liquid inlet channel f1 is a coaxial and concentric frustum-shaped through hole. Its diameter gradually decreases from the first circular liquid inlet e1 to the first circular liquid outlet g1, completely penetrating the 2 mm thick outer wall of the substrate. The total length of the channel is the same as the outer wall thickness, which is 2 mm. The waist and the bottom edge of the liquid inlet end form an angle of 71°. Both ends are coaxially connected to the first circular liquid inlet e1 and the first circular liquid outlet g1, respectively.

[0048] The electrolyte enters from the external electrolyte environment through the first circular inlet e1 and seeps out from the first circular outlet g1, flowing from the large opening to the small opening, thus achieving selective permeation control of protons in the electrolyte.

[0049] The nitrogen transport channel group and the electrolyte transport channel group are staggered in the thickness direction of the substrate wall by 1 mm. Both groups of channels are arranged in a 2 mm equidistant square array. The center-to-center distance between adjacent through holes is 2 mm. The through holes are evenly distributed on the substrate wall. The straight wall region on one side of the gas-liquid split micro-nano porous electrode device is a 10×10 unit array. The bottom arc region of the device is fitted with the same specification of channels along the arc surface, forming a continuous and complete flow field system with the straight wall region array.

[0050] The overall dimensions of the first gas-liquid split micro-nano porous electrode device a1 are: length 40 mm, width 40 mm, height 50 mm; the inner diameter of the first N2 main intake pressure stabilizing cavity h1 is 36 mm, and the cross-sectional area of ​​the flow passage is 1017.36 mm²; the side surface of the catalyst layer on the inner wall of the substrate is the reaction area.

[0051] This embodiment achieves directional enrichment and efficient transport of nitrogen through the gradually expanding structure of the nitrogen flow channel (small inlet, large outlet), and achieves selective permeation control of protons through the gradually contracting structure of the electrolyte flow channel (large inlet, small outlet). By constructing a micro-ordered three-phase reaction network inside the catalyst layer through the staggered arrangement of gas-liquid channels, it simultaneously solves the dual technical problems of limited nitrogen mass transfer and severe hydrogen evolution side reactions.

[0052] Example 2

[0053] This embodiment provides a gas-liquid splitting micro / nano porous electrode device with an S-shaped flow field structure, the structure of which is as follows: Figures 5-8 As shown.

[0054] The S-shaped gas-liquid splitting micro / nano porous electrode device includes a second gas-liquid splitting micro / nano porous electrode device a2, which uses a U-shaped hollow iron group metal substrate as a supporting base plate, and the internal hollow region is the second N2 main air intake and pressure stabilizing cavity h2. The substrate wall is divided into an inner wall and an outer wall, with an inner wall thickness of 3 mm and an outer wall thickness of 2 mm.

[0055] The inner wall of the substrate is provided with a nitrogen transmission channel assembly, which consists of an array of several S-shaped air inlet holes. Specifically, the S-shaped air inlet holes include a second S-shaped air inlet b2, a second S-shaped main air inlet channel c2, and a second S-shaped air outlet d2.

[0056] The second S-shaped air inlet b2 is located on the inner wall of the substrate, facing the N2 main air intake and pressure stabilization cavity inside the device. It is a small-diameter end with a single-hole flow area of ​​0.8 mm². 2 The intake end opening serves as the second S-shaped main intake duct c2.

[0057] The second S-shaped outlet d2 is located on the inner wall of the substrate, on the side of the catalyst layer. It is the large-diameter end, with an effective mass transfer area of ​​3.1 mm per pore. 2 The outlet opening serves as the main intake channel c2 in the second S-shape.

[0058] The second S-shaped air intake mainstream c2 is an S-shaped through hole, the diameter of which gradually increases from the second S-shaped air intake b2 to the second S-shaped air outlet d2, completely penetrating the 3 mm thick inner wall of the substrate. The total length of the flow channel is the same as the thickness of the inner wall, which is 3 mm. The two ends are connected to the second S-shaped air intake b2 and the second S-shaped air outlet d2, respectively.

[0059] Nitrogen gas enters from the N2 main intake pressure stabilizing chamber h2 through the second S-shaped intake port b2 and is ejected from the second S-shaped outlet port d2. The flow direction is from the small port to the large port, realizing the directional enrichment and transport of nitrogen gas.

[0060] An electrolyte transport channel assembly is provided on the outer wall of the substrate, consisting of an array of several S-shaped liquid inlet holes. Specifically, the S-shaped liquid inlet holes include a second S-shaped liquid inlet e2, a second S-shaped liquid inlet main channel f2, and a second S-shaped liquid outlet g2.

[0061] The second S-shaped inlet e2 is located on the outer wall of the substrate, facing the external electrolyte environment. It is the large-diameter end, with a single-hole flow area of ​​7.1 mm². 2 The inlet end opening serves as the main inlet channel f2 in the second S-shape.

[0062] The second S-shaped outlet g2 is located on the inner wall of the substrate, on the side of the catalyst layer. It is the small-diameter end, with an effective mass transfer area of ​​2.0 mm per pore. 2 The outlet opening serves as the main inlet channel f2 in the second S-shape.

[0063] The second S-shaped liquid inlet channel f2 is an S-shaped through hole with a diameter that gradually decreases from the second S-shaped liquid inlet e2 to the second S-shaped liquid outlet g2. It completely penetrates the 2 mm thick outer wall of the substrate. The total length of the channel is the same as the thickness of the outer wall, which is 2 mm. Both ends are connected to the second S-shaped liquid inlet e2 and the second S-shaped liquid outlet g2, respectively.

[0064] The electrolyte enters from the external electrolyte environment through the second S-shaped inlet e2 and seeps out from the second S-shaped outlet g2, flowing from the large opening to the small opening, thus achieving selective permeation control of protons in the electrolyte.

[0065] The nitrogen transport channel group and the electrolyte transport channel group are staggered in the thickness direction of the substrate wall by 1 mm. Both groups of channels are arranged in a 2 mm equidistant square array. The center-to-center distance between adjacent through holes is 2 mm. The through holes are evenly distributed on the substrate wall. The straight wall region on one side of the gas-liquid split micro-nano porous electrode device is a 10×10 unit array. The bottom arc region of the device is fitted with the same specification of channels along the arc surface, forming a continuous and complete flow field system with the straight wall region array.

[0066] The overall dimensions of the second gas-liquid split micro-nano porous electrode device a2 are: length 40 mm, width 40 mm, height 50 mm; the inner diameter of the internal second N2 main inlet pressure stabilizing cavity h2 is 36 mm, and the cross-sectional area of ​​the flow passage is 1017.36 mm²; the side surface of the catalyst layer on the inner wall of the substrate is the reaction area.

[0067] This embodiment changes the path shape of the channel to S-shape based on the circular flow field, further increasing the tortuosity of the fluid path and enhancing the ability to control nitrogen transport and proton suppression.

[0068] Example 3

[0069] This embodiment provides a gas-liquid splitting micro / nano porous electrode device with an L-shaped flow field structure, the structure of which is as follows: Figures 9-12 As shown.

[0070] The L-shaped gas-liquid splitting micro / nano porous electrode device includes a third gas-liquid splitting micro / nano porous electrode device a3, which uses a U-shaped hollow iron group metal substrate as the supporting base plate, and the internal hollow region is the third N2 main intake pressure stabilizing cavity h3. The substrate wall is divided into an inner wall and an outer wall, with an inner wall thickness of 3 mm and an outer wall thickness of 2 mm.

[0071] The inner wall of the substrate is provided with a nitrogen transmission channel assembly, which consists of an array of several L-shaped air inlet holes. Specifically, the L-shaped air inlet holes include a third L-shaped air inlet b3, a third L-shaped main air inlet channel c3, and a third L-shaped air outlet d3.

[0072] The third L-shaped air inlet b3 is located on the inner wall of the substrate, facing the N2 main air intake and pressure stabilization cavity inside the device. It is a small-diameter end with a single-hole flow area of ​​0.8 mm². 2 The intake end opening serves as the third L-shaped main intake duct c3.

[0073] The third L-shaped outlet d3 is located on the inner wall of the substrate, on the side of the catalyst layer. It is the large-diameter end, with an effective mass transfer area of ​​3.1 mm per pore. 2 The outlet opening serves as the third L-shaped main intake duct c3.

[0074] The third L-shaped air intake mainstream c3 is an L-shaped through hole, the diameter of which gradually increases from the third L-shaped air intake b3 to the third L-shaped air outlet d3, completely penetrating the 3 mm thick inner wall of the substrate. The total length of the flow channel is the same as the thickness of the inner wall, which is 3 mm. The two ends are connected to the third L-shaped air intake b3 and the third L-shaped air outlet d3, respectively.

[0075] Nitrogen gas enters from the N2 main intake pressure stabilizing chamber h3 through the third L-shaped intake port b3 and exits from the third L-shaped outlet port d3. The flow direction is from the small port to the large port, realizing the directional enrichment and transmission of nitrogen gas.

[0076] The outer wall of the substrate is provided with an electrolyte transport channel assembly, which consists of an array of several L-shaped liquid inlet holes. Specifically, the L-shaped liquid inlet holes include a third L-shaped liquid inlet e3, a third L-shaped liquid inlet main channel f3, and a third L-shaped liquid outlet g3.

[0077] The third L-shaped inlet e3 is located on the outer wall of the substrate, facing the external electrolyte environment. It is the large-diameter end, with a single-hole flow area of ​​7.1 mm². 2 The inlet end opening serves as the third L-shaped main inlet channel f3.

[0078] The third L-shaped outlet g3 is located on the inner wall of the substrate, on the side of the catalyst layer. It is the small-diameter end, with an effective mass transfer area of ​​2.0 mm per pore. 2 The outlet opening serves as the third L-shaped main inlet channel f3.

[0079] The third L-shaped liquid inlet channel f3 is an L-shaped through hole. Its diameter gradually decreases from the third L-shaped liquid inlet e3 to the third L-shaped liquid outlet g3, completely penetrating the 2 mm thick outer wall of the substrate. The total length of the channel is the same as the outer wall thickness, which is 2 mm. Both ends are connected to the third L-shaped liquid inlet e3 and the third L-shaped liquid outlet g3, respectively.

[0080] The electrolyte enters from the external electrolyte environment through the third L-shaped inlet e3 and seeps out from the third L-shaped outlet g3, flowing from the large opening to the small opening, thus achieving selective permeation control of protons in the electrolyte.

[0081] The nitrogen transport channel group and the electrolyte transport channel group are staggered in the thickness direction of the substrate wall by 1 mm. Both groups of channels are arranged in a 2 mm equidistant square array. The center-to-center distance between adjacent through holes is 2 mm. The through holes are evenly distributed on the substrate wall. The straight wall region on one side of the gas-liquid split micro-nano porous electrode device is a 10×10 unit array. The bottom arc region of the device is fitted with the same specification of channels along the arc surface, forming a continuous and complete flow field system with the straight wall region array.

[0082] The overall dimensions of the third gas-liquid split micro-nano porous electrode device a3 are: length 40 mm, width 40 mm, height 50 mm; the inner diameter of the internal third N2 main intake pressure regulating cavity h3 is 36 mm, and the cross-sectional area of ​​the flow passage is 1017.36 mm²; the side surface of the catalyst layer on the inner wall of the substrate is the reaction area.

[0083] Based on the circular flow field, this embodiment changes the path shape of the channel to an L-shape, increasing the tortuosity of the fluid transmission path through right-angle turns, thereby further enhancing the resistance control of electrolyte transmission.

[0084] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0085] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A gas-liquid splitting micro / nano porous electrode device, characterized in that, The electrode device includes a U-shaped hollow matrix; The system comprises a multi-level micro-nano pore directional flow channel system disposed on the wall of the U-shaped hollow matrix. The multi-level micro-nano pore directional flow channel system is divided into a nitrogen transport channel group on the inner wall side and an electrolyte transport channel group on the outer wall side. The nitrogen transport channel group is connected to the N2 main inlet pressure stabilizing cavity inside the U-shaped hollow matrix and the inner wall catalyst layer side of the U-shaped hollow matrix. The electrolyte transport channel group is connected to the external electrolyte environment and the inner wall catalyst layer side of the U-shaped hollow matrix. Both the nitrogen transport channel group and the electrolyte transport channel group are composed of several micropore arrays with different structures and porosities. The nitrogen transport channel group and the electrolyte transport channel group are staggered in the matrix wall thickness direction to form a gas-liquid split directional transport flow field system.

2. The gas-liquid splitting micro / nano porous electrode device as described in claim 1, characterized in that, The micro-nano channels in the nitrogen transport channel assembly have a gradually expanding structure. Nitrogen enters from the small-diameter end facing the N2 main inlet pressure stabilizing cavity and exits from the large-diameter end facing the inner wall catalyst layer, achieving directional enrichment and efficient transport of nitrogen at the catalyst layer interface. The micro-nano channels in the electrolyte transport channel assembly have a gradually contracting structure. Electrolyte enters from the large-diameter end facing the external electrolyte environment and exits from the small-diameter end facing the inner wall catalyst layer, achieving selective permeation control of protons from the electrolyte to the catalyst layer interface.

3. The gas-liquid splitting micro / nano porous electrode device as described in claim 1, characterized in that, The substrate of the U-shaped hollow matrix is ​​a metal-based material such as nickel-based, iron-based, or titanium alloy, or a carbon-based material.

4. The gas-liquid splitting micro / nano porous electrode device as described in claim 1, characterized in that, The electrode devices are fabricated using micro / nano fabrication, precision CNC machining, or ion etching processes.

5. The gas-liquid splitting micro / nano porous electrode device as described in claim 2, characterized in that, The inlet end of the nitrogen gas transmission channel assembly is located on the inner wall side of the U-shaped hollow substrate, facing the main N2 gas intake and stabilizing cavity, and the outlet end is located on the inner wall catalytic layer side of the U-shaped hollow substrate. The diameter of the inlet end is smaller than that of the outlet end. The liquid inlet end of the electrolyte transmission channel assembly is located on the outer wall side of the U-shaped hollow substrate, facing the external electrolyte environment, and the outlet end is located on the inner wall catalytic layer side of the U-shaped hollow substrate. The diameter of the inlet end is larger than that of the outlet end.

6. The gas-liquid splitting micro / nano porous electrode device as described in claim 1, characterized in that, The flow field structure of the multi-level micro-nano channel directional flow system can be any one of a circular flow field, an S-shaped flow field, or an L-shaped flow field.

7. The gas-liquid splitting micro / nano porous electrode device as described in claim 6, characterized in that, When the flow field structure is a circular flow field, the air inlet of the nitrogen transmission channel group is a coaxial and concentric frustum-shaped air inlet, and the liquid inlet of the electrolyte transmission channel group is a coaxial and concentric frustum-shaped liquid inlet; when the flow field structure is an S-shaped flow field, the air inlet is an S-shaped air inlet, and the liquid inlet is an S-shaped liquid inlet; when the flow field structure is an L-shaped flow field, the air inlet is an L-shaped air inlet, and the liquid inlet is an L-shaped liquid inlet.

8. The gas-liquid splitting micro / nano porous electrode device as described in claim 6 or 7, characterized in that, The through holes in the nitrogen gas transmission channel group and the through holes in the electrolyte transmission channel group are arranged in an equally spaced square array, with a center-to-center distance of 1-3 mm between adjacent through holes. The through holes are evenly distributed on the wall of the U-shaped hollow substrate. The misalignment of the through holes in the nitrogen gas transmission channel group and the through holes in the electrolyte transmission channel group in the thickness direction of the substrate wall is 0.5-2 mm.

9. The gas-liquid splitting micro / nano porous electrode device as described in claim 1, characterized in that, The inner wall thickness of the U-shaped hollow matrix is ​​2-4 mm, and the outer wall thickness is 1-3 mm; the overall length of the U-shaped hollow matrix ranges from 10-100 mm, the width ranges from 10-100 mm, and the height ranges from 20-200 mm; the inner diameter of the N2 main intake pressure stabilizing cavity ranges from 8-96 mm.

10. The application of the gas-liquid splitting micro / nano porous electrode device according to any one of claims 1 to 9, characterized in that, Application of the gas-liquid splitting micro / nano porous electrode device in aqueous electrochemical ammonia synthesis.

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