Electrolytic tank for directly producing hydrogen from seawater and method for directly producing hydrogen from seawater

Abstract

The invention discloses an electrolytic bath for directly producing hydrogen from seawater and a method for directly producing hydrogen from seawater, and relates to the technical field of seawater electrolysis hydrogen production. The electrolytic cell is of a double-layer partition structure, seawater with the salinity of 20-35 g / L (the conductivity is 30-50 mS / cm) is directly introduced into an anode high-salt area, and the conductivity of a cathode low-salt area is maintained to be lt; and a dynamic adjustment membrane (DAM, the thickness is 100 microns, and the aperture is 0.5-1 micron) is arranged in the membrane to control ion permeation. The anode uses an IrO-MoS2 composite catalyst (the proportion of IrO2 is 20%), the cathode uses MoS2 (the loading capacity is 2.0 mg / cm < 2 >), the operation voltage is 1.8-2.3 V, the current density is 0.8-1.6 A / cm < 2 >, and the temperature is 40-60 DEG C. According to the device, the H2 yield is 2.0-2.3 L / min, the efficiency is 85-90%, and the service life is gt; in 6000 hours, a Cl2 by-product 1t is obtained; and 0.05%. The method is free of pretreatment, high in corrosion resistance and suitable for green hydrogen energy production in coastal areas.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by electrolysis of seawater, and more particularly to an electrolyzer for directly producing hydrogen from seawater and a method for directly producing hydrogen from seawater. Background Art

[0002] With the growing global demand for clean energy, hydrogen has attracted widespread attention as an efficient, zero-emission energy carrier. Seawater, due to its abundant reserves and widespread distribution, has become an ideal source of raw materials for hydrogen production. However, direct electrolysis of seawater to produce hydrogen faces many technical challenges, especially the high salinity of seawater (about 20-35g / L) and the Cl - Ion-pair corrosion in electrolysis equipment is a problem. Traditional technologies typically address this issue by pre-treating seawater to reduce salinity or applying corrosion-resistant coatings to the electrode surfaces. However, these methods often require high energy consumption, have limited efficiency, and struggle to meet the demands of long-term operation. Therefore, developing efficient, corrosion-resistant electrolyzer designs suitable for direct hydrogen production from seawater has become a research hotspot.

[0003] In recent years, seawater electrolysis hydrogen production technology has made some progress in electrolyzer structure design and electrocatalyst development. For example, Yu et al. (2019) reported a seawater electrolysis catalyst based on non-noble metal nitride in Nature Communications (Yu L, et al., "Non-noble metal-nitride based electrocatalystsfor high-performance alkaline seawater electrolysis," Nat. Commun., 2019, 10(1): 5106). This study achieved efficient hydrogen and oxygen evolution in alkaline seawater using NiMoN catalysts, verifying the potential of nitrides in high-salt environments. However, this technology does not involve a dynamic ion regulation mechanism, Cl - The long-term impact of ions on the cathode has not yet been resolved, and the electrolytic cell structure design is relatively simple, failing to fully optimize corrosion resistance.

[0004] Similarly, Ning et al. (2022) discussed in Energy & Environmental Science the improvement of catalyst performance in seawater electrolysis by electrochemical reconstruction (Ning MH, et al., "Boosting efficient alkaline fresh water and seawater electrolysis via electrochemical reconstruction," Energy Environ. Sci., 2022, 15 (9): 3945-3957). This study improved the catalytic efficiency by generating an active layer through surface reconstruction, but the stability test in high-salinity seawater was limited to short-term operation and failed to meet the needs of long-term industrial use. In addition, the partition design of the electrolyzer and the by-product control strategy have not been fully explored.

[0005] In the patent field, CN 103952719 B (“A catalyst for hydrogen production by electrolysis of water and its preparation method”, published on March 1, 2017) proposed a transition metal-based catalyst for water decomposition to produce hydrogen. This patent improved the hydrogen evolution performance by optimizing the catalyst formula, but was not designed for high-salinity seawater environments. - The ionic corrosion problem has not been fully addressed. Similarly, CN 110344078 B ("A foamed nickel@cobalt molybdenum phosphide / nickel-iron double hydroxide electrode, its preparation method, and application," published on January 5, 2018) reports a bifunctional electrode suitable for water splitting in alkaline electrolytes. However, this patent does not address the specific requirements of direct seawater electrolysis, such as dynamic ion isolation and byproduct suppression, limiting its scope of application.

[0006] In addition, Sun et al. (2020) studied solar-driven alkaline water electrolysis technology in Advanced Functional Materials (Sun ZX, et al., "Solar-driven alkaline water electrolysis with multifunctional catalysts," Adv. Funct. Mater., 2020, 30(27): 2002138). This study achieved high electrolysis efficiency through multifunctional catalysts, but lacked long-term stability testing in actual seawater and did not propose specific structural optimization solutions for Cl- ion corrosion. CN115161676A ("A seawater direct hydrogen production device and method", publication date: 2022.10.11) describes a seawater electrolysis device that emphasizes overall structural improvement, but does not fully address the lack of dynamic ion regulation and catalyst corrosion resistance, and the stability of long-term operation still needs to be verified.

[0007] Through comprehensive analysis of existing technologies, the following main problems can be summarized:

[0008] 1. Equipment corrosion problem: The corrosion effect of Cl- ions in high salinity seawater on the electrolytic cell components is significant, and the existing design is difficult to maintain long-term stability.

[0009] 2. High energy consumption and low efficiency: The traditional electrolysis process consumes a lot of energy and has low hydrogen production rate, limiting the technical and economic efficiency.

[0010] 3. Insufficient control of by-products: The generation of chlorine and other by-products in the electrolysis process increases the process complexity and environmental risk.

[0011] To address the above deficiencies, the present invention proposes a seawater direct hydrogen production electrolytic cell and a seawater direct hydrogen production method. By introducing a double-layer partition structure, dynamic adjustment membrane (DAM), and high-efficiency corrosion-resistant catalyst, the present invention can achieve efficient and stable hydrogen production in seawater with a salinity of 20-35 g / L. Compared with existing technologies (such as CN 115161676 A), the present invention not only optimizes the electrolytic cell structure, but also effectively reduces the corrosion of Cl - ions on equipment through a dynamic ion regulation mechanism, while improving energy utilization efficiency and long-term operation stability. This design aims to overcome the limitations of traditional technologies and provide a new solution for the industrialization of seawater direct hydrogen production. SUMMARY

[0012] The present invention aims to provide an electrolyzer structure design and application method for direct hydrogen production from seawater, addressing existing issues such as corrosion, high energy consumption, low efficiency, and inadequate byproduct control in high-salinity seawater environments. Through innovative structural design and a dynamic ion control mechanism, this approach achieves efficient, stable, and low-cost hydrogen production, providing a new technical path for the industrial application of seawater hydrogen production.

[0013] In order to achieve the above object, the present invention adopts the following technical solutions:

[0014] An electrolyzer for direct hydrogen production from seawater, comprising an anode high-salinity region, a cathode low-salinity region, and a dynamic adjustment membrane (DAM) located between the anode high-salinity region and the cathode low-salinity region;

[0015] The anode in the anode high salt area adopts IrO2-MoS2 composite catalyst, wherein IrO2 accounts for 20wt% and MoS2 accounts for 80wt%;

[0016] The cathode in the cathode low-salt zone uses MoS2 catalyst;

[0017] The dynamic adjustment membrane is made of a composite of Nafion and polyethersulfone, wherein Nafion accounts for 70wt% and polyethersulfone accounts for 30wt%, with a thickness of 100μm and a pore size of 0.5-1μm; the fixed frame connecting the DAM is made of polyetheretherketone (PEEK) material.

[0018] The dynamic adjustment membrane is driven by a vibration driver. - and Cl - The permeability (controlled at 5-10%), to prevent Cl - The ions penetrate into the cathode region and protect the cathode from corrosion.

[0019] The effect of adopting the above technical solution is that the present invention designs a new type of electrolytic cell, which is divided into an anode high-salinity area and a cathode low-salinity area. Through partition isolation, high-salinity seawater (salinity 20-35g / L) is directly treated, effectively avoiding Cl - Ion corrosion of the cathode;

[0020] Traditional electrolytic cells usually use a single electrolyte environment, which makes it difficult to isolate Cl - Ions cause the cathode to corrode rapidly in a high-salt environment. The double-layer partition design of the present invention achieves efficient ion isolation in the process of direct hydrogen production from seawater for the first time, significantly protecting the cathode and extending the life of the equipment.

[0021] Traditional membrane technologies are mostly static in design and cannot adapt to the dynamic changes in ion concentration during the electrolysis process. DAM uses a vibration mechanism to adjust ion permeability in real time according to electrolysis conditions, which not only improves cathodic protection but also enhances the long-term stability of the electrolyzer.

[0022] Preferably, the anode has a MoS2 layer thickness of 3-5 nm, a loading of 1.8 mg / c, and a specific surface area of ​​180-220 m 2 / g. It inhibits Cl2 formation and promotes the oxygen evolution reaction (OER). The anode's composite structure and specific loading design inhibit Cl2 formation and improve hydrogen evolution efficiency.

[0023] Preferably, the anode is prepared by the following method:

[0024] Preparation of IrO2 substrate: IrCl3 solution was coated on a titanium substrate and heat treated at 400℃ for 2h to form an IrO2 layer;

[0025] MoS2 layer deposition: MoS2 precursor was hydrothermally reacted at 180°C for 6 hours and deposited on the IrO2 surface. The MoS2 precursor consisted of Na2MoO4 and thiourea in a molar ratio of 1:4.

[0026] Post-treatment: The product was washed alternately with deionized water and ethanol three times and dried in vacuum at 80 °C for 4 h to obtain the anode.

[0027] Preferably, the MoS2 loading in the cathode is 2.0 mg / cm 2 , grain size 10-15nm, edge active sites account for >45%, and effectively promote the hydrogen evolution reaction (HER).

[0028] Preferably, the cathode is prepared by the following method:

[0029] Substrate preparation: titanium substrate is selected, and the surface is pickled to increase the roughness;

[0030] MoS2 deposition: A mixed solution of Na2MoO4 and thiourea was reacted at 160°C for 8 hours and then deposited on a titanium substrate using a hydrothermal method. The concentration of Na2MoO4 was 0.05 mol / L and the concentration of thiourea was 0.2 mol / L.

[0031] Post-treatment: the product was washed with deionized water 5 times and dried under vacuum at 100° C. for 6 h to obtain the cathode.

[0032] The beneficial effect of adopting the above technical solution is that the anode MoS2 layer acts as a protective layer to effectively inhibit the generation of Cl2, and IrO2 provides efficient oxygen evolution reaction (OER) activity; the edge active sites of the cathode MoS2 optimize the hydrogen evolution performance, and synergistically achieve efficient hydrogen production.

[0033] Preferably, the anode is fixed by a titanium bolt to ensure that the contact resistance is less than 0.1Ω; the cathode is fixed by a PEEK clamp to ensure that the contact resistance is less than 0.05Ω; and the distance between the cathode and the anode is 5 mm.

[0034] Preferably, the preparation method of the dynamic adjustment membrane is as follows:

[0035] 1) Nafion solution and polyethersulfone particles were mixed in a mass ratio of 7:3 and stirred at 80°C for 2 hours; wherein the Nafion solution contained 5 wt% DuPont; and the polyethersulfone particles had a particle size of <50 μm;

[0036] 2) The film was made by casting and hot-pressed at 150°C to obtain a dynamic adjustment film.

[0037] Preferably, the shell of the electrolytic cell is made of titanium alloy, and the composition of the titanium alloy is Ti-6Al-4V; a 316L stainless steel water cooling pipe is arranged in the electrolytic cell to connect the anode high salt area and the cathode low salt area, with a flow rate of 1L / min and a temperature control accuracy of ±1°C.

[0038] Another object of the present invention is to provide a method for directly producing hydrogen from seawater, using the above-mentioned electrolyzer for directly producing hydrogen from seawater, comprising the following steps:

[0039] (1) Initialization: seawater is introduced into the high-salinity area of ​​the anode and pure water is introduced into the low-salinity area of ​​the cathode, and the membrane is dynamically adjusted to start vibration;

[0040] (2) Electrolysis operation: voltage controlled at 1.8-2.3V, current density 0.8-1.6A / cm 2 , the temperature is maintained at 40-60°C, O2 (overpotential 280mV) and trace Cl2 (<0.05%) are precipitated at the anode, and H2 (overpotential 140mV) is precipitated at the cathode;

[0041] (3) Gas collection: H2 (purity > 99.9%) and O2, Cl2 were separated by a hydrophobic polytetrafluoroethylene membrane and then absorbed by a 0.1 mol / L NaOH solution.

[0042] Preferably, in step (1), the salinity of seawater is 20-35 g / L, and the flow rate is 5 L / h; the conductivity of pure water is <1 μS / cm, and the flow rate is 0.5 L / h; the frequency of vibration is 50 Hz, and the amplitude is 0.1 mm.

[0043] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. No pretreatment required: 20-35g / L high-salinity seawater can be used directly, eliminating complex pretreatment steps, simplifying the process, and reducing energy consumption and equipment investment costs.

[0045] 2. High efficiency performance: at 1.8-2.3V voltage and 0.8-1.6A / cm 2Under the current density, the hydrogen yield reaches 2.0-2.3L / min, and the energy efficiency is as high as 85-90%, which is superior to traditional technology.

[0046] 3. Long-life operation: The equipment life exceeds 6000h. The dynamic adjustment of DAM keeps the salinity in the cathode area at <0.1g / L, and the corrosion resistance is improved by 70%, significantly extending the service life of the equipment.

[0047] 4. By-product control: The Cl2 by-product content is controlled at <0.05% and treated by NaOH absorption to further reduce environmental impact and process complexity.

[0048] 5. Economical: The anode uses an IrO2-MoS2 composite catalyst (IrO2 accounts for only 20%), and the cathode uses a MoS2 catalyst, significantly reducing costs compared to all-precious metal catalysts. Furthermore, the optimized equipment structure further enhances overall economical efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0050] Figure 1 The figure is a flow chart of the electrolytic cell structure;

[0051] Figure 2 is the relationship curve between H2 production rate and voltage;

[0052] Figure 3 is the XRD curve of MoS2;

[0053] Figure 4 is the XPS curve of MoS2;

[0054] Figure 5 This is a structural diagram of the electrolytic cell of the present invention;

[0055] Among them, in the figure:

[0056] 1-anode high-salt area, 11-anode, 2-cathode low-salt area, 21-cathode, 3-dynamic adjustment membrane, 4-vibration driver, 5-housing, 6-water cooling tube, 7-PEEK fixture. DETAILED DESCRIPTION

[0057] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0058] Example 1

[0059] See also Figure 1 This example describes in detail the preparation, assembly, and characterization process of the various components of the electrolyzer to ensure that the equipment can operate efficiently in a high-salt seawater environment.

[0060] 1. Anode high salt area

[0061] Design parameters:

[0062] 1) Volume: 10L, meeting industrial-grade electrolysis requirements.

[0063] 2) Inner wall material: titanium alloy (Ti-6Al-4V, thickness 2mm, Ti content>99.5%), prepared by cold rolling forming process, surface polished, corrosion resistance meets ASTMB265 standard.

[0064] Electrode preparation: Composite catalyst with IrO2 accounting for 20wt% and MoS2 accounting for 80wt%.

[0065] 1) Loading capacity: 1.8 mg / cm 2 , ensuring uniform coating through precise weighing.

[0066] 2) Electrode area: 200 cm 2 , with a rectangular design and dimensions of 20cm×10cm.

[0067] 3) Preparation steps:

[0068] (1) Preparation of IrO2 substrate: IrCl3 solution (concentration 0.1 mol / L) was coated on a titanium substrate and heat treated at 400°C for 2 h to form an IrO2 layer.

[0069] (2) MoS2 layer deposition: MoS2 precursor (Na2MoO4 and thiourea, molar ratio 1:4) was reacted at 180 °C for 6 h by a hydrothermal method and deposited on the IrO2 surface.

[0070] (3) Post-treatment: The product was washed alternately with deionized water and ethanol three times and dried in vacuum at 80°C for 4 h. Installation: The electrode was fixed to the anode chamber with titanium bolts to ensure that the contact resistance was <0.1Ω.

[0071] 2. Cathode low salt area

[0072] Design parameters:

[0073] 1) Volume: 2 L, designed for small volume to maintain low salinity environment.

[0074] 2) Inner wall material: Polytetrafluoroethylene (thickness 1.5 mm, temperature resistance > 200°C), prepared by injection molding, ensuring chemical inertness.

[0075] Electrode preparation: MoS2 catalyst.

[0076] 1) Loading: 2.0 mg / cm 2 , precise control of coating amount.

[0077] 2) Grain size: 12 nm, optimized for hydrogen evolution performance.

[0078] 3) Preparation steps:

[0079] (1) Substrate preparation: Titanium substrate was selected, the surface was treated with acid washing (10% H2SO4, 30 minutes) to increase roughness.

[0080] (2) MoS2 deposition: A mixed solution of Na2MoO4 (0.05 mol / L) and thiourea (0.2 mol / L) was reacted at 160°C for 8h by hydrothermal method, and deposited on the titanium substrate.

[0081] (3) Post-processing: The product was washed with deionized water for 5 times, and vacuum dried at 100°C for 6h.

[0082] Installation: The electrode was fixed to the cathode chamber by PEEK clamp, with contact resistance <0.05Ω.

[0083] 3. Dynamic adjustment membrane (DAM)

[0084] Design parameters:

[0085] 1) Material: Made of Nafion (70wt%) and polyether sulfone (30wt%), with ion selectivity and mechanical strength.

[0086] 2) Thickness: 100 μm, prepared by hot pressing method.

[0087] 3) Pore size: Average 0.8 μm (range 0.5-1 μm).

[0088] Preparation steps:

[0089] 1) Mix Nafion solution (DuPont, 5wt%) with polyether sulfone particles (particle size <50 μm) at a mass ratio of 7:3, stir at 80°C for 2h.

[0090] 2) The film was made by casting and hot pressing at 150°C with a thickness of 100 μm.

[0091] Vibration drive:

[0092] 1) Parameters: frequency 50Hz, power 5W, amplitude 0.1mm.

[0093] 2) Installation: Fix it with the PEEK frame and connect the driver to an external power supply to ensure uniform vibration transmission.

[0094] 3) Characterization: The permeability was controlled at 5-10% in a 0.5 mol / L NaCl solution. The test value of Example 1 was 7.5%, which effectively isolated the high-salinity area from the low-salinity area.

[0095] 4. Housing and auxiliary systems

[0096] Shell: Titanium alloy (Ti-6Al-4V), size 30cm×20cm×15cm, pressure resistance 10bar, formed by CNC machining.

[0097] Cooling system:

[0098] 1) Material: 316L stainless steel water cooling tube, diameter 6mm, wall thickness 0.5mm.

[0099] 2) Operating parameters: water flow rate 1L / min, temperature control accuracy ±1°C, connected to an external circulating water pump.

[0100] Electrode spacing: 5 mm. The electrodes and DAM are fixed by a PEEK frame to ensure structural stability.

[0101] Assembly steps:

[0102] 1) Install the anode and cathode electrodes in the anode high-salinity area and cathode low-salinity area respectively.

[0103] 2) The DAM is fixed to the center of the electrolytic cell through a PEEK frame, connected to the vibration driver, and connected to the anode high-salinity area and the cathode low-salinity area through a 316L stainless steel water-cooling pipe.

[0104] 3) The shell is sealed with a silicone gasket to ensure airtightness.

[0105] Figure 3 The XRD curve of MoS2 is shown. The main characteristic peaks include (002) peak (2θ≈14.38°), (100) peak (2θ≈32.68°), (103) peak (2θ≈39.54°), etc. The position, intensity and shape of these peaks directly reflect the crystal structure characteristics, crystallinity and application performance of MoS2 material in electrolytic cell. Among them, the (002) peak is the strongest characteristic peak, located at 2θ≈14.38°, corresponding to the interplanar spacing. The presence and intensity of this peak indicate that MoS2 has a highly ordered layered structure. This structural characteristic ensures the efficient hydrogen evolution performance of MoS2 in the cathode of the electrolyzer and promotes the hydrogen evolution reaction (HER).

[0106] Figure 4 This is the XPS curve of MoS2. The XPS curve shows the characteristic peaks of Mo3d, S2p and S2s. 4+ and S 2- The chemical state reflects the typical two-dimensional layered structure of MoS2, with its coordinated unsaturated edge Mo and S atoms providing efficient hydrogen evolution active sites. In Example 1, the MoS2 grain size is 12nm, and the active site accounts for 48%, which is consistent with the Mo3d peak intensity of the XPS curve, supporting its efficient hydrogen evolution performance (H2 production rate 2.15L / min, efficiency 88%).

[0107] Example 2

[0108] This example verifies the operating performance and hydrogen production efficiency of the electrolyzer in an actual seawater environment.

[0109] 1. Raw materials

[0110] 1) Anode high-salinity area: Bohai Sea water, salinity 32g / L (main components: NaCl 28g / L, MgSO4

[0111] 1.5 g / L), conductivity 48 mS / cm, pH 8.0, and suspended particles were removed by filtration (turbidity < 1 NTU).

[0112] 2) Cathode low-salt zone: high-purity water (prepared by reverse osmosis), with an initial conductivity of 0.5 μS / cm.

[0113] 2. Operating conditions

[0114] 1) Voltage: 2.1 V, precisely controlled by a DC power supply (Keysight E36300).

[0115] 2) Current density: 1.2A / cm 2 , optimizing efficiency and energy consumption.

[0116] 3) Temperature: 50°C, regulated by a water cooling system and a heater (power 500W).

[0117] 4) Flow rate:

[0118] (1) Seawater: 5 L / h, delivered by a peristaltic pump (model Masterflex L / S).

[0119] (2) Pure water: 0.5L / h, to ensure stability in the low-salt area.

[0120] 3. Test results

[0121] 1) Hydrogen production rate: 2.15 L / min, purity 99.9%.

[0122] 2) Oxygen production rate: 1.07 L / min, consistent with the theoretical value (H2:O2=2:1).

[0123] 3) Cl2 by-product: The measured content is <0.04% (meets the design requirement of <0.05%), determined by iodine titration and treated by absorption with 0.1 mol / L NaOH solution. The tail gas emissions meet environmental protection standards.

[0124] 4) Electrolysis efficiency: 88%, calculated based on input electrical energy and hydrogen production.

[0125] 5) Energy consumption: 4.6kWh / Nm 3 H2, recorded by the energy meter.

[0126] 6) Salinity of cathode area: 0.08g / L.

[0127] Additional details:

[0128] 1) Operation time: Continuous operation for 24 hours to ensure data reliability.

[0129] 2) Gas collection: A hydrophobic polytetrafluoroethylene membrane (pore size 0.2 μm) was used to separate H2 and O2, and the collection device was connected to the gas bag.

[0130] Figure 2 This is the relationship curve between H2 yield and voltage. The curve shows the change of H2 yield in the voltage range of 1.8-2.3V, with a peak of 2.3L / min at 2.1V, reflecting the optimal operating conditions.

[0131] Example 3

[0132] This example evaluates the long-term operational stability of an electrolytic cell in a high-salt environment.

[0133] 1. Test conditions

[0134] 1) Seawater composition: Salinity 35 g / L (NaCl 35 g / L, MgSO4 2 g / L), simulating an extreme marine environment.

[0135] 2) Voltage: 2.1V.

[0136] 3) Current density: 1.2A / cm 2 .

[0137] 4) Operating time: Continuous operation of 6000h (about 250 days).

[0138] 5) Environmental control: temperature 50°C, flow rate same as in Example 2.

[0139] 2. Test results

[0140] 1) Hydrogen yield:

[0141] (1) Initial value: 2.2 L / min.

[0142] (2) After 6000h: 2.0L / min, attenuation rate 9%, indicating slow performance degradation.

[0143] 2) Electrolysis efficiency:

[0144] (1) Initial value: 89%.

[0145] (2) After 6000h: 82%, down 7.9%, still maintaining high efficiency.

[0146] 3) Lifespan prediction:

[0147] (1) Decay rate: 0.015% / h, calculated based on the change of productivity and efficiency over time.

[0148] (2) Predicted lifespan: approximately 7200 h (hydrogen production rate > 1.76 L / min), meeting industrial application requirements.

[0149] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0150] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electrolyzer for direct hydrogen production from seawater, characterized in that: It includes an anode high-salt area, a cathode low-salt area, and a dynamic adjustment membrane located between the anode high-salt area and the cathode low-salt area; The anode in the anode high salt area adopts IrO2-MoS2 composite catalyst, wherein IrO2 accounts for 20wt% and MoS2 accounts for 80wt%; The cathode in the cathode low-salt zone uses MoS2 catalyst; The dynamic adjustment membrane is made of Nafion and polyethersulfone, wherein Nafion accounts for 70wt% and polyethersulfone accounts for 30wt%, with a thickness of 100μm and a pore size of 0.5-1μm; The dynamic adjustment membrane is driven by a vibration driver.

2. The electrolyzer for direct hydrogen production from seawater according to claim 1, characterized in that: In the anode, the MoS2 layer thickness is 3-5nm, the loading is 1.8mg / c, and the specific surface area is 180-220m 2 / g.

3. The electrolyzer for direct hydrogen production from seawater according to claim 2, characterized in that: The anode is prepared by the following method: Preparation of IrO2 substrate: IrCl3 solution was coated on a titanium substrate and heat treated at 400℃ for 2h to form an IrO2 layer; MoS2 layer deposition: MoS2 precursor was hydrothermally reacted at 180°C for 6 hours and deposited on the IrO2 surface. The MoS2 precursor consisted of Na2MoO4 and thiourea in a molar ratio of 1:

4. Post-treatment: The product was washed alternately with deionized water and ethanol three times and dried in vacuum at 80 °C for 4 h to obtain the anode.

4. The electrolyzer for direct hydrogen production from seawater according to claim 1, characterized in that: In the cathode, the MoS2 loading is 2.0 mg / cm 2 , grain size 10-15nm, edge active sites account for >45%.

5. The electrolyzer for direct hydrogen production from seawater according to claim 4, characterized in that: The cathode is prepared by the following method: Substrate preparation: titanium substrate is selected, and the surface is pickled to increase the roughness; MoS2 deposition: A mixed solution of Na2MoO4 and thiourea was reacted at 160°C for 8 hours and then deposited on a titanium substrate using a hydrothermal method. The concentration of Na2MoO4 was 0.05 mol / L and the concentration of thiourea was 0.2 mol / L. Post-treatment: the product was washed with deionized water 5 times and dried under vacuum at 100° C. for 6 h to obtain the cathode.

6. The electrolyzer for direct hydrogen production from seawater according to claim 1, characterized in that: The anode is fixed by a titanium bolt to ensure that the contact resistance is less than 0.1Ω; the cathode is fixed by a PEEK clamp to ensure that the contact resistance is less than 0.05Ω; the distance between the cathode and the anode is 5 mm.

7. The electrolyzer for direct hydrogen production from seawater according to claim 1, characterized in that: The preparation method of the dynamic adjustment membrane is as follows: 1) Nafion solution and polyethersulfone particles were mixed in a mass ratio of 7:3 and stirred at 80°C for 2 hours; wherein the Nafion solution contained 5 wt% DuPont and the polyethersulfone particles had a particle size of <50 μm; 2) The film was made by casting and hot-pressed at 150°C to obtain a dynamic adjustment film.

8. The electrolyzer for direct hydrogen production from seawater according to claim 1, characterized in that: The shell of the electrolytic cell is made of titanium alloy with a composition of Ti-6Al-4V; a 316L stainless steel water cooling pipe is arranged in the electrolytic cell to connect the anode high-salt area and the cathode low-salt area, with a flow rate of 1L / min and a temperature control accuracy of ±1°C.

9. A method for directly producing hydrogen from seawater, characterized in that: The electrolyzer for direct hydrogen production from seawater according to any one of claims 1 to 9 comprises the following steps: (1) Initialization: seawater is introduced into the high-salinity area of ​​the anode, pure water is introduced into the low-salinity area of ​​the cathode, and the membrane is dynamically adjusted to start vibration; (2) Electrolysis operation: voltage controlled at 1.8-2.3V, current density 0.8-1.6A / cm 2 , the temperature is maintained at 40-60℃, O2 and trace Cl2 are precipitated at the anode, and H2 is precipitated at the cathode; (3) Gas collection: H2, O2 and Cl2 are separated by a hydrophobic polytetrafluoroethylene membrane and then absorbed by a 0.1 mol / L NaOH solution.

10. The method for direct hydrogen production from seawater according to claim 9, characterized in that: In step (1), the salinity of seawater is 20-35 g / L, and the flow rate is 5 L / h; the conductivity of pure water is <1 μS / cm, and the flow rate is 0.5 L / h; the frequency of vibration is 50 Hz, and the amplitude is 0.1 mm.

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