Novel anion exchange membrane photoelectrocatalytic water splitting reactor and preparation method

Abstract

The present application belongs to the technical field of solar photoelectrocatalytic water splitting to produce hydrogen, and discloses a novel anion exchange membrane photoelectrocatalytic water splitting reactor and a preparation method. The reactor is sequentially attached from back to front with an end plate, a cathode current collector, a cathode flow channel plate, a FeCoNi cathode, an anion exchange membrane, an anode current collector, an alpha-Fe2O3 photoanode, quartz glass, and an anode flow channel plate. The anode current collector has a flow channel for the cathode plate in the middle. The FeCoNi cathode is directly and closely attached to the alpha-Fe2O3 photoanode through the anion exchange membrane. The anode flow channel plate has an optical window in the middle, and the quartz glass is attached to the inner side of the optical window. The present application can reduce the number of bubbles and the diameter of the bubbles by using the fluid shear force through the electrolyte flow regulation function of the reactor. The present application provides a unique reactor design idea for improving the photoelectrochemical performance under high light concentration.

Description

Technical Field

[0001] This invention belongs to the field of solar photovoltaic catalytic water splitting for hydrogen production technology, and particularly relates to a novel anion exchange membrane photovoltaic catalytic water splitting reactor and its preparation method. Background Technology

[0002] Solar energy is a vast, clean, and pollution-free renewable energy source. However, it suffers from drawbacks such as low energy density and large fluctuations. Hydrogen, as a promising energy carrier, possesses advantages such as high energy density and high stability. Solar-hydrogen energy technology converts fluctuating solar energy into stable chemical energy, enabling the stable use of solar energy and representing an important approach to solving increasingly serious energy and environmental problems. Since preliminary research on TiO2, photoelectrochemical (PEC) water splitting for hydrogen production has been considered a very promising solar energy utilization technology because it can directly capture and utilize solar energy to split water for hydrogen production. However, the relatively low hydrogen production efficiency limits the large-scale application of PEC technology.

[0003] To improve the scalability and hydrogen yield of PEC water splitting for hydrogen production, increasing the electrode area is a common method. Hydrogen production efficiency is increased by expanding the effective reaction area and the solar absorption area. However, with the increase in electrode area, it becomes difficult to ensure catalyst uniformity. Furthermore, the substrate resistance increases, leading to increased overall reactor losses. The problems of catalyst inhomogeneity and increased electrode substrate resistance can be addressed through modularization. However, each submodule contains independent wiring and current collector plates, resulting in accumulated ohmic losses at the inter-module interface contact resistance. Therefore, excessive modularization inevitably increases the ohmic losses of the current collector during series module processes. Thus, the ohmic losses caused by modularization urgently need to be addressed.

[0004] By concentrating sunlight, the incident power of sunlight can be increased without increasing the electrode area, solving the problems of resistance in large-area electrode substrates and current collection losses in modular electrodes. Concentration increases the number of incident photons to excite more photogenerated carriers, thereby increasing the current density of PEC. Concentration also leads to increased temperature, which enhances molecular dynamics and catalytic activity through thermal activation. However, the increased current density from high-concentration also leads to a significant increase in gaseous products, which negatively impacts solar incidence and mass transfer within the reactor. The gas shielding effect affects effective reaction sites and reduces the actual contact area between the electrolyte and electrodes. The number and morphology of bubbles may change under concentrated light, leading to increased scattering losses of incident light. Bubbles may also degrade mass transfer performance, thus affecting PEC performance. Mitigating the effects of bubbles and enhancing mass transfer can be addressed through reactor structural design. However, traditional PEC water splitting reactors for hydrogen production are mostly membrane-free, with conductive glass as the electrode substrate and the electrolyte in a static state. The large spatial distance between the cathode and anode in traditional membrane-free reactors results in severe mass transfer and ohmic losses. Furthermore, traditional membrane-free reactors struggle to separate and effectively remove the gaseous products from the anode and cathode, leading to reduced hydrogen production efficiency in PEC and impacting the utilization of subsequent gaseous products. Therefore, there is an urgent need to develop a high-efficiency concentrating reactor to reduce mass transfer and ohmic losses during PEC water splitting, thereby increasing hydrogen production yield and efficiency. Summary of the Invention

[0005] To overcome the problems existing in related technologies, the present invention discloses a novel anion exchange membrane photoelectrocatalytic water splitting hydrogen production reactor and its preparation method, specifically relating to a novel concentrated AEM-PEC (Anion Exchange Membrane PhotoElectroChemical) water splitting hydrogen production reactor. More particularly, it relates to an anion exchange membrane photoelectrocatalytic water splitting hydrogen production reactor operating under high-concentration light.

[0006] The technical solution is as follows: A novel anion exchange membrane photoelectrocatalytic water splitting hydrogen production reactor, wherein the reactor is sequentially attached and installed from back to front with an end plate, a cathode current collector, a cathode flow channel plate, an FeCoNi cathode, an anion exchange membrane, an anode current collector, an α-Fe2O3 photoanode, quartz glass, and an anode flow channel plate;

[0007] A flow channel for the electrolyte and the cathode plate for ion transport is opened in the middle of the anode current collector, located between the FeCoNi cathode and the α-Fe2O3 photoanode cathode and anode electrodes;

[0008] The FeCoNi cathode is installed in the middle of the cathode flow channel plate and is directly and tightly attached to the α-Fe2O3 photoanode through an anion exchange membrane.

[0009] An optical window is provided in the middle of the anode flow channel plate, and quartz glass is attached to the inside of the optical window to allow incident light to irradiate the surface of the α-Fe2O3 photoanode.

[0010] Both the FeCoNi cathode and the α-Fe2O3 photoanode substrates are adhered with porous fibrous Ti fiber mats.

[0011] The lower part of the side wall of the anode flow channel plate is provided with an electrolyte injection port channel for electrolyte injection; the upper part of the side wall of the anode flow channel plate is provided with an electrolyte discharge channel for the discharge of O2 and reflux electrolyte.

[0012] Furthermore, the electrolyte is pumped in by a water pump from the electrolyte injection port channel at the lower side wall of the anode flow channel plate, immersing the α-Fe2O3 photoanode, and flows out from the electrolyte discharge channel on the other side. Under different light intensities and temperatures, the flow rate of the electrolyte is forcibly increased, and the fluid shear force is used to remove oxygen bubbles generated on the surface of the α-Fe2O3 photoanode due to the oxidation reaction.

[0013] The cathode flow channel plate has a second H2 discharge channel for H2 discharge and a first H2 discharge channel for H2 discharge respectively on the upper and lower parts of its side wall.

[0014] Another objective of this invention is to provide a method for preparing a novel anion exchange membrane photoelectrocatalytic water splitting reactor for hydrogen production, comprising:

[0015] Preparation of S1, FeCoNi cathode and α-Fe2O3 photoanode;

[0016] S2, Preparation of anion exchange membrane;

[0017] After the FeCoNi cathode, anion exchange membrane, and α-Fe2O3 photoanode are prepared, they are assembled in the following order from back to front: end plate, cathode current collector, cathode flow channel plate, FeCoNi cathode, anion exchange membrane, anode current collector, α-Fe2O3 photoanode, quartz glass, and anode flow channel plate.

[0018] In step S1, the preparation of the α-Fe2O3 photoanode includes:

[0019] FeCl3-6H2O and urea were dissolved in deionized water as a precursor solution;

[0020] The Ti fiber mat was ultrasonically cleaned in acetone, ethanol and deionized water in sequence to remove impurities; the cleaned Ti fiber mat was then acid etched in HCl.

[0021] The acid-etched Ti fiber mat placed in the precursor solution is heated to allow FeOOH to grow uniformly on the Ti fiber mat.

[0022] After naturally cooling to room temperature, rinse the Ti fiber felt with FeOOH grown with deionized water to remove surface impurities.

[0023] Finally, the anode is heated and calcined, and then naturally cooled to obtain α-Fe2O3 photoanode.

[0024] The cleaned Ti fiber mat was acid-etched in 30 mL HCl at 80°C for 10 minutes;

[0025] The acid-etched Ti fiber mat placed in the precursor solution was heated at 100°C for 8 hours to allow FeOOH to grow uniformly on the Ti fiber mat.

[0026] At 5°C min -1 Heating at a rate of 100°C and calcining at 550°C for 2 hours.

[0027] In step S1, the preparation of the FeCoNi cathode includes:

[0028] The mixed solution of FeNiCo, isopropanol, deionized water and FAA-3-SOLUT-10-EtOH was ultrasonically treated, and the mixed solution was uniformly sprayed onto Ti fiber felt; the sprayed cathode was annealed and calcined to obtain FeCoNi cathode.

[0029] The preparation of the anion exchange membrane in step S2 includes: immersing the anion exchange membrane in KOH solution to convert it into hydroxide form, thereby obtaining the treated anion exchange membrane.

[0030] Combining all the above technical solutions, the beneficial effects of this invention are as follows: This invention utilizes anion exchange membranes to reduce the electrode spacing, thereby decreasing the ohmic impedance of the reactor and preventing the mixing of hydrogen and oxygen. By concentrating a large area of ​​sunlight onto a small area of ​​electrodes, the requirements for catalyst uniformity and substrate resistance are reduced. As the photoelectrocatalytic current density increases, the influence of bubbles on light absorption by the electrodes, the contact between the electrodes and the electrolyte, and mass transfer within the reactor increases. By utilizing the electrolyte flow rate adjustment function of the reactor and fluid shear force, the number and diameter of bubbles can be reduced, thus optimizing performance. This invention provides a unique reactor design approach for improving photoelectrochemical performance under high-concentration light. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure;

[0032] Figure 1 This is a schematic diagram of the novel anion exchange membrane photoelectrocatalytic water splitting hydrogen production reactor provided in this embodiment of the invention;

[0033] Figure 2 This is a physical diagram of the preparation process of the α-Fe2O3 photoanode provided in the embodiments of the present invention;

[0034] Figure 3 This is a photograph of the Ti fiber felt provided in an embodiment of the present invention after calcination.

[0035] Figure 4 This is a microscopic morphology image of the Ti fiber felt of the present invention.

[0036] Figure 5 For the present invention Figure 4 A magnified image of Ti fiber felt (400x magnification).

[0037] Figure 6 This is a flowchart of the preparation method of the novel anion exchange membrane photoelectrocatalytic water splitting hydrogen production reactor provided in the embodiments of the present invention;

[0038] Figure 7 To illustrate this invention, titanium felt was subjected to different acid etching times, and the performance of Fe2O3 was tested using linear sweep voltammetry in a three-electrode system.

[0039] Figure 8 Performance diagram of the AEM-PEC water splitting reactor of the present invention equipped with an unannealed cathode;

[0040] Figure 9 Performance diagram of the AEM-PEC water splitting reactor of the present invention equipped with an annealed cathode;

[0041] Figure 10 For traditional single-tank reactors at 0, 100, and 200 mW cm⁻¹ -2 Electrochemical impedance spectroscopy under different light intensities;

[0042] Figure 11 The anion exchange membrane reactor designed for this invention operates at 0, 100, and 200 mW / cm². -2 Electrochemical impedance spectroscopy under different light intensities;

[0043] Figure 12 The electrochemical impedance of the reactor at different flow rates under concentrated light and at an operating temperature of 60°C.

[0044] Figure 13 The electrochemical impedance of the reactor at different flow rates when the reactor is operated at 70°C under concentrated light.

[0045] In the diagram: 1. End plate; 2. Cathode current collector; 3. Cathode flow channel plate; 4. FeCoNi cathode; 5. Anion exchange membrane; 6. Anode current collector; 7. α-Fe2O3 photoanode; 8. Quartz glass; 9. Anode flow channel plate; 10. Cathode plate flow channel; 11. Optical window; 12. Electrolyte injection port channel; 13. Electrolyte discharge channel; 14. Second H2 discharge channel; 15. First H2 discharge channel. Detailed Implementation

[0046] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0047] For ease of understanding, traditional reactor structures include membrane-free reactors and H-shaped membrane reactors. Membrane-free reactors have a main body of transparent quartz glass, with the anode and cathode immersed in the electrolyte, making gas separation impossible. H-shaped membrane reactors use a membrane to spatially separate the anode and cathode, allowing for the separation of gases at both electrodes. In these reactors, the anode and cathode are far apart, resulting in significant mass transfer (mass transfer mainly refers to the transport of ions in the electrolyte between the anode and cathode) losses, and they cannot remove air bubbles.

[0048] The innovation of this invention lies in the fact that the close bonding of the anode, anion exchange membrane (AEM), and cathode reduces mass transfer losses between the electrodes. The reactor uses an anion exchange membrane, the electrolyte is KOH, and the working environment is alkaline, which is beneficial for accelerating the oxidation reaction of Fe₂O₃. (The principle is that, unlike ordinary exchange membranes that allow cations and anions to pass through, proton exchange membranes only allow H₂...) + Therefore, the anion exchange membrane used in this invention only allows OH- - The passage of ions allows the reactor to operate in a strongly alkaline environment. Since the anodic oxidation reaction involves four electron transfers and the cathodic reduction reaction only involves two electron transfers in water electrolysis, the anodic reaction is relatively slow, limiting the overall reaction rate of the electrolytic cell. The strongly alkaline environment provides a large amount of OH- ions for the anodic oxidation reaction. - This promotes the forward shift of the oxidation reaction. Therefore, using anion exchange membranes to operate the reactor under alkaline conditions can increase the anodic oxidation reaction rate.

[0049] The membrane electrode design structure and the forced convection liquid feeding method on the anode side of the present invention can reduce the number of bubbles on the α-Fe2O3 photoanode side by using fluid shear force while the electrolyte on the anode current collector 6 side is immersed in the α-Fe2O3 photoanode, thus avoiding the generation of large bubbles and effectively solving the problems of mass transfer loss, light scattering loss and reduction of the effective contact area between the anode and the electrolyte α-Fe2O3 photoanode 7 caused by bubbles.

[0050] Anion exchange membranes can be used to separate the oxygen and hydrogen generated by the positive and negative electrodes (anion exchange membranes only allow OH-). - By preventing gas from passing through, the oxygen produced at the anode is discharged on the anode side, and the hydrogen produced at the cathode is discharged on the cathode side, so the gases do not mix, which is beneficial for subsequent gas utilization.

[0051] Example 1, such as Figure 1 As shown, the novel anion exchange membrane photoelectrocatalytic water splitting hydrogen production reactor (AEM-PEC) provided in this embodiment of the invention is sequentially attached and installed from back to front as follows: end plate 1, cathode current collector 2, cathode flow channel plate 3, FeCoNi cathode 4, anion exchange membrane 5, anode current collector 6, α-Fe2O3 photoanode 7, quartz glass 8, and anode flow channel plate 9.

[0052] The cathode current collector 2 is a gold-plated Cu plate, and the anode current collector 6 is a Ti plate;

[0053] The anode current collector 6 has a flow channel 10 located between the FeCoNi cathode 4 and the α-Fe2O3 photoanode 7, which supplies electrolyte and ion transport to the cathode plate.

[0054] The FeCoNi cathode 4 is installed in the middle of the cathode flow channel plate 3 and is directly and tightly attached to the α-Fe2O3 photoanode 7 through the anion exchange membrane 5.

[0055] An optical window 11 is provided in the middle of the anode flow channel plate 9, and a quartz glass 8 is attached to the inside of the optical window 11 to allow incident light to irradiate the surface of the α-Fe2O3 photoanode.

[0056] The center lines of the FeCoNi cathode 4, anion exchange membrane 5, α-Fe2O3 photoanode 7, cathode plate flow channel 10, quartz glass 8, and optical window 11 are all on a horizontal line.

[0057] Both FeCoNi cathode 4 and α-Fe2O3 photoanode 7 have porous fibrous Ti fiber felts adhered to their substrates.

[0058] An exemplary physical diagram of the preparation process of α-Fe2O3 photoanode 7 is shown below. Figure 2Ti fiber felt is processed through un-acid-impregnated Ti fiber felt, acid-impregnated Ti fiber felt, hydrothermal Ti fiber felt, and finally calcined Ti fiber felt. Actual images are shown below. Figure 3 ;

[0059] Figure 4 The image shows the microstructure of Ti fiber felt. Figure 5 for Figure 4 A magnified image of Ti fiber felt (400x magnification); Figure 5 Fe2O3 nanorods are visible growing on the fiber felt;

[0060] It is known that Ti fiber felt with a porous fibrous structure has excellent ion transport and electronic conductivity, making it suitable for use in α-Fe2O3 concentrating reactors. Therefore, this invention selects Ti fiber felt as the substrate for both the photoanode and cathode.

[0061] The lower part of the side wall of the anode flow channel plate 9 is provided with an electrolyte injection port channel 12 for electrolyte injection; the upper part of the side wall of the anode flow channel plate 9 is provided with an electrolyte discharge channel 13 for the discharge of O2 and reflux electrolyte.

[0062] For example, the electrolyte is pumped in by a water pump from the electrolyte injection port channel 12 at the lower side wall of the anode flow channel plate 9, immersing the α-Fe2O3 photoanode 7, and flows out from the electrolyte discharge channel 13 on the other side. Under different light intensities and temperatures, the flow rate of the electrolyte is forcibly increased, and the oxygen bubbles generated on the surface of the α-Fe2O3 photoanode 7 due to the oxidation reaction are removed by the fluid shear force.

[0063] The cathode flow channel plate 3 has a second H2 discharge channel 14 for H2 discharge and a first H2 discharge channel 15 for H2 discharge on the upper and lower parts of its side wall, respectively.

[0064] In practical operation, sunlight shines on the α-Fe₂O₃ photoanode through the quartz glass "optical window." Electrons are excited from the valence band to the conduction band by photons and conducted to the anode current collector. Then, the electrons move to the cathode through the external circuit. H₂O reacts with holes to produce O₂. O₂ is discharged from the anode flow channel plate 9 along with the electrolyte. OH⁻ produced by the oxidation reaction... - The H2 moves through the anion exchange membrane to the FeCoNi cathode side and participates in a reduction reaction with electrons to generate H2. The H2 is discharged through the second H2 discharge channel 14 of the cathode flow channel plate 3 and the first H2 discharge channel 15 for H2 removal.

[0065] The AEM-PEC water splitting reactor is structurally adapted to concentrated light. The photoanode generates more heat under high-concentration light. To prevent thermal deformation of the reactor, most reactor components are made of metal. Quartz glass is used to ensure good light transmittance under concentrated light. The AEM-PEC water splitting reactor employs anion exchange membranes, enabling close contact between the cathode and photoanode, reducing mass transfer impedance and ohmic impedance. Furthermore, it compresses the gas, preventing large air bubbles from forming between the electrodes.

[0066] The electrolyte enters the anode chamber through the electrolyte injection port channel 12 on the side of the anode flow channel plate 9, migrates to the surface of the α-Fe2O3 photoanode 7, and is continuously immersed on the active surface. The designed flow pattern facilitates forced convection of the high-speed electrolyte on the surface of the α-Fe2O3 photoanode 7, using fluid shear force to break up large bubbles and reduce the gas shielding effect. Simultaneously, this forced convection also has a cooling effect, mitigating the excessively high temperature caused by high-concentration light, thus protecting the reactor and stabilizing its operating temperature. The design of the second H2 discharge channel 14 and the first H2 discharge channel 15 for H2 removal on the cathode flow channel plate 3 also meets the need for timely gas overflow from the cathode side. Using Ti fiber felt as the electrode substrate is advantageous because, on the one hand, the ohmic impedance of Ti fiber felt does not change significantly with increasing light intensity, making it suitable for light concentration. On the other hand, its porous fiber structure is beneficial for ion transport, which is perfectly suited for the AEM-PEC reactor requiring anion transport. The current collection method uses a gold-plated Cu plate for the cathode and a Ti foil for the photoanode. This ensures ion transport and prevents corrosion while maintaining close contact between the electrodes, thus achieving stable current collection.

[0067] For example, by using an anion exchange membrane 5 (AEM membrane), the FeCoNi cathode 4 and the α-Fe2O3 photoanode 7 can be separated. Oxygen produced by the oxidation reaction of the α-Fe2O3 photoanode 7 is discharged through the anode flow channel plate 9 along with the electrolyte, while hydrogen produced by the reduction reaction of the FeCoNi cathode 4 is discharged through the cathode flow channel plate 3 along with a small amount of electrolyte. Through the design of the membrane reactor of this invention, the electrolyte is forcibly introduced, and the increased flow rate utilizes fluid shear force to reduce the number of bubbles on the surface of the α-Fe2O3 photoanode 7, avoiding the formation of large bubbles and ensuring that the electrolyte fully soaks the α-Fe2O3 photoanode 7, thereby improving performance.

[0068] Example 2, Figure 6 The preparation method of the novel anion exchange membrane photoelectrocatalytic water splitting hydrogen production reactor provided in this embodiment of the invention includes:

[0069] Preparation of S1, FeCoNi cathode 4, and α-Fe2O3 photoanode 7;

[0070] S2, Preparation of anion exchange membrane 5;

[0071] After the FeCoNi cathode 4, anion exchange membrane 5, and α-Fe2O3 photoanode 7 are prepared, they are assembled by attaching the mounting end plate 1, cathode current collector 2, cathode flow channel plate 3, FeCoNi cathode 4, anion exchange membrane 5, anode current collector 6, α-Fe2O3 photoanode 7, quartz glass 8, and anode flow channel plate 9 in that order from back to front.

[0072] For example, in step S1, the preparation of the α-Fe₂O₃ photoanode 7 includes: preparing the α-Fe₂O₃ photoanode using a hydrothermal method. 0.81 g of FeCl₃-6H₂O and 0.18 g of urea are dissolved in 40 mL of deionized water as a precursor solution. Conventional reactors are grown on FTO conductive glass substrates, while this reactor is grown on titanium felt, resulting in a larger specific surface area and a higher loading of ferric oxide for the same dosage of reagent, as detailed in Table 1.

[0073] Table 1. Statistics on Ferric Oxide Loading

[0074] Ti fiber mat (2cm×2cm×0.25mm) was ultrasonically cleaned sequentially in acetone, ethanol, and deionized water for 20 minutes each to remove impurities. To ensure uniform FeOOH growth, the cleaned Ti fiber mat was acid-etched in 30mL HCl at 80°C for 10 minutes.

[0075] Titanium felt was subjected to acid etching for different times, and the properties of Fe2O3 were tested by linear sweep voltammetry in a three-electrode system. Figure 7 , Figure 7 The study demonstrates that Fe2O3 prepared after 10 minutes of acid etching on titanium felt exhibits the highest current density at 1.23V, highlighting the advantage of time-efficient etching.

[0076] The acid-etched Ti fiber mat, placed in the precursor solution, was heated at 100°C for 8 hours to allow FeOOH to grow uniformly on the Ti fiber mat. After naturally cooling to room temperature, the FeOOH-coated Ti fiber mat was rinsed with deionized water to remove surface impurities. Finally, it was heated at 5°C for 1 minute... -1 The mixture was heated at a rate of [missing information] and calcined at 550°C for 2 hours. After natural cooling, an α-Fe₂O₃ photoanode was obtained.

[0077] For example, in step S1, the preparation of the FeCoNi cathode 4 includes: preparing the FeNiCo cathode by spraying. A mixed solution of 8 mg FeNiCo, 2 mL isopropanol, 1 mL deionized water, and 0.3 mL 5% FAA-3-SOLUT-10-EtOH is ultrasonically treated for 1 h to ensure uniform dispersion. The mixed solution is then uniformly sprayed onto a Ti fiber felt (2 cm × 2 cm × 0.25 mm) at 60°C. Referring to the annealing method for preparing α-Fe2O3 photoanodes, the sprayed cathode is annealed at 5°C for 5 min. -1 Annealing at a heating rate of 100°C and calcining at 550°C for 2 hours.

[0078] The performance of the AEM-PEC water splitting reactor was tested using linear sweep voltammetry. Figure 8 The performance of the AEM-PEC water splitting reactor equipped with an unannealed cathode is examined. If the cathode is not annealed, its performance will degrade after long-term operation in a high-temperature concentrated light environment, affecting the overall performance of the reactor. Figure 9 The performance of the annealed cathode assembled in the AEM-PEC water splitting reactor is shown. The annealed cathode exhibits excellent stability, and its performance remained largely unchanged even after prolonged operation at high temperatures. This demonstrates the advantages of the annealing process.

[0079] For example, the preparation of the anion exchange membrane 5 (AEM) in step S2 includes: anion exchange membrane pretreatment. The anion exchange membrane (3cm × 3cm, Piperion A40) is immersed in 1 M KOH solution for about 2 hours to convert it into hydroxide form, which can improve the OH... - Ion transport rate.

[0080] As demonstrated by the above embodiments, this invention provides a design approach for a photoelectrocatalytic water splitting reactor. This reactor operates under concentrated light and can be combined with non-precious metal catalysts, resulting in reduced material costs for hydrogen production through photoelectrocatalytic water splitting. It also reduces mass transfer and ohmic losses, solves the bubble problem in practical applications of photoelectrocatalytic water splitting, and improves the efficiency of hydrogen production from water splitting.

[0081] This invention applies anion exchange membrane reactors to the field of photoelectrocatalytic water splitting for hydrogen production, and is adapted to high-concentration light. It solves the problem of large ohmic losses in mass transfer in traditional reactors. By combining small-area electrodes with concentrated light, it avoids the problems of increased substrate ohmic impedance and current collection losses caused by large-area electrodes. It also mitigates the problems of mass transfer losses caused by increased bubble formation due to increased current density under high-concentration light, incident light scattering losses, and reduced effective contact area between the electrode and electrolyte.

[0082] Photoelectrochemical water splitting for hydrogen production suffers from low current, hindering commercialization. Traditional methods increase the current by enlarging the electrode, but this increases the ohmic impedance of the substrate and current collection losses, leading to reduced efficiency. This approach utilizes a small-area electrode combined with focusing to increase energy input, thereby improving the photoelectrochemical current and hydrogen production performance. Furthermore, it reduces the problem of increased bubble formation caused by increased current under high-concentration focusing.

[0083] This invention overcomes the technical limitations of low hydrogen production from photoelectrocatalytic water splitting, which hinders practical application, and the difficulty in resolving bubble problems as current density increases.

[0084] To further illustrate the effects of the embodiments of the present invention, the following experiments were conducted. Regarding the anion exchange membrane photoelectrocatalytic (AEM-PEC) water splitting and hydrogen production reactor, which utilizes anion exchange membranes to shorten the distance between the anode and cathode and reduce ohmic impedance, the present invention conducted the following experiments.

[0085] like Figure 10 For traditional single-tank reactors at 0, 100, and 200 mW cm⁻¹ -2 Electrochemical impedance spectroscopy under different light intensities;

[0086] Figure 11 The anion exchange membrane reactor designed for this invention operates at 0, 100, and 200 mW / cm². -2 Electrochemical impedance spectroscopy under different light intensities.

[0087] The test potential is 1.23 V vs. CE, and the test frequency range is 0.1-10. 5 Hz, the tested AC amplitude is 10mV. At 200mW cm⁻¹ -2 Under illumination, the charge transfer resistance of a conventional reactor is approximately 140 Ω, while that of the AEM-PEC reactor is approximately 107 Ω. Furthermore, it is clearly evident that compared to a conventional single-chamber PEC reactor, the electrochemical impedance spectroscopy (EIS) plot of the AEM-PEC reactor designed in this invention exhibits a smaller radius of curvature under dark conditions. This result indicates that the AEM-PEC reactor enhances charge transfer and reduces mass transfer and ohmic losses. Typically, an EIS plot reflects the mass transfer and ohmic impedance of a test system, generally presented as a semi-circular arc. The diameter of the semi-circular arc is considered the charge transfer resistance; intuitively, a larger arc indicates greater impedance and poorer charge transfer. For the sake of data comparison, the entire arc under dark conditions is not shown, but it is still visually apparent that the arc of the AEM-PEC reactor is smaller.

[0088] This approach addresses the issue of reducing the requirements for catalyst uniformity and substrate resistivity by concentrating sunlight over a large area onto a small electrode area; Barbera et al. [1] The electrode area was reduced from 0.25 cm².2 Expand to 25cm 2 When the electrolysis voltage reached 0.6V, the photocurrent increased from 0.03mA to 5.25mA, indicating increased hydrogen production. However, the STH efficiency decreased significantly from 1.8% to 0.13%, attributed to increased substrate ohmic resistance and catalyst inhomogeneity after electrode scaling. Modularizing large-area electrodes can solve the problems of catalyst inhomogeneity and increased electrode substrate resistance. Vilanova et al. [2] Given a fixed total electrode area, the problem of large-area electrodes can be avoided by connecting multiple reaction modules with small-area electrodes in series. However, the current density of each reaction module can only reach 0.2~0.5mA cm⁻¹ at a voltage of 1.6V. -2 The reason for the lower current density is that each module has its own independent wires and current collectors. Ohmic losses will occur at the connection points of these small module current collectors. This means that excessive modularity will inevitably increase the current collector ohmic losses during the series connection of modules. [3] The relevant papers are as follows:

[0089] [1]BARBERA O, LO VECCHIO C, TROCINO S, et al. Solar to hydrogenconversion by a 25 cm 2 -photoelectrochemical cell with upscaled components[J].Renewable Energy, 2024, 224: 120154.

[0090] [2]VILANOVA A, DIAS P, AZEVEDO J, et al. Solar water splitting undernatural concentrated sunlight using a 200 cm2 photoelectrochemical-photovoltaic device[J]. Journal of Power Sources, 2020, 454: 227890.

[0091] [3]MOSS B, BABACAN O, KAFIZAS A, et al. A Review of InorganicPhotoelectrode Developments and Reactor Scale-Up Challenges for SolarHydrogen Production[J]. ADVANCED ENERGY MATERIALS, 2021, 11(13): 2003286.

[0092] Regarding the issue of bubble removal mentioned, Figure 12 , Figure 13 The electrochemical impedance spectroscopy of the reactor was tested at different flow rates under concentrated light and operating temperatures of 60℃ and 70℃. Figure 12 , Figure 13 As can be seen from this, increasing the flow rate and using fluid shear force to remove bubbles can reduce mass transfer impedance (the diameter of the semicircle in the impedance diagram decreases).

[0093] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention and within the spirit and principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A novel anion exchange membrane photoelectrocatalytic water splitting reactor for hydrogen production, characterized in that, The reactor is attached and installed from back to front as follows: end plate (1), cathode current collector (2), cathode flow channel plate (3), FeCoNi cathode (4), anion exchange membrane (5), anode current collector (6), α-Fe2O3 photoanode (7), quartz glass (8), and anode flow channel plate (9). The anode current collector (6) has a flow channel (10) in the middle, located between the FeCoNi cathode (4) and the α-Fe2O3 photoanode (7) cathode and anode, for supplying electrolyte and ion transport. The FeCoNi cathode (4) is installed in the middle of the cathode flow channel plate (3) and is directly and tightly attached to the α-Fe2O3 photoanode (7) through the anion exchange membrane (5); An optical window (11) is provided in the middle of the anode flow channel plate (9), and a quartz glass (8) is attached to the inside of the optical window (11).

2. The novel anion exchange membrane photoelectrocatalytic water splitting reactor for hydrogen production according to claim 1, characterized in that, Both the FeCoNi cathode (4) and the α-Fe2O3 photoanode (7) have porous fibrous Ti fiber felts adhered to their substrates.

3. The novel anion exchange membrane photoelectrocatalytic water splitting reactor according to claim 1, characterized in that, The lower side wall of the anode flow channel plate (9) is provided with an electrolyte injection port channel (12) for electrolyte injection; the upper side wall of the anode flow channel plate (9) is provided with an electrolyte discharge channel (13) for the discharge of O2 and reflux electrolyte.

4. The novel anion exchange membrane photoelectrocatalytic water splitting reactor for hydrogen production according to claim 3, characterized in that, The electrolyte is pumped in by a water pump from the electrolyte injection port channel (12) at the lower side wall of the anode flow channel plate (9), immersing the α-Fe2O3 photoanode (7), and flows out from the electrolyte discharge channel (13) on the other side. Under different light intensities and temperatures, the flow rate of the electrolyte is forcibly increased, and the oxygen bubbles generated on the surface of the α-Fe2O3 photoanode (7) due to the oxidation reaction are removed by the fluid shear force.

5. The novel anion exchange membrane photoelectrocatalytic water splitting reactor according to claim 1, characterized in that, The cathode flow channel plate (3) has a second H2 discharge channel (14) and a first H2 discharge channel (15) respectively provided on the upper and lower parts of its side wall for H2 discharge.

6. A method for preparing a novel anion exchange membrane photoelectrocatalytic water splitting reactor for hydrogen production, characterized in that, This method is used to prepare the novel anion exchange membrane photoelectrocatalytic water splitting hydrogen production reactor according to any one of claims 1-5, and the preparation method includes: Preparation of S1, FeCoNi cathode (4) and α-Fe2O3 photoanode (7); S2, Preparation of anion exchange membrane (5); After the S3, FeCoNi cathode (4), anion exchange membrane (5), and α-Fe2O3 photoanode (7) are prepared, they are assembled in the following order from back to front: end plate (1), cathode current collector (2), cathode flow channel plate (3), FeCoNi cathode (4), anion exchange membrane (5), anode current collector (6), α-Fe2O3 photoanode (7), quartz glass (8), and anode flow channel plate (9).

7. The preparation method of the novel anion exchange membrane photoelectrocatalytic water splitting hydrogen production reactor according to claim 6, characterized in that, In step S1, the preparation of the α-Fe2O3 photoanode (7) includes: FeCl3-6H2O and urea were dissolved in deionized water as a precursor solution; The Ti fiber mat was ultrasonically cleaned in acetone, ethanol and deionized water in sequence to remove impurities; the cleaned Ti fiber mat was then acid etched in HCl. The acid-etched Ti fiber mat placed in the precursor solution was heated to allow FeOOH to grow uniformly on the Ti fiber mat. After naturally cooling to room temperature, rinse the Ti fiber felt with FeOOH grown with deionized water to remove surface impurities. After heating and calcining, and then naturally cooling, α-Fe2O3 photoanode (7) was obtained.

8. The method for preparing the novel anion exchange membrane photoelectrocatalytic water splitting hydrogen production reactor according to claim 7, characterized in that, The cleaned Ti fiber mat was acid-etched in 30 mL HCl at 80°C for 10 minutes; The acid-etched Ti fiber mat placed in the precursor solution was heated at 100°C for 8 hours to allow FeOOH to grow uniformly on the Ti fiber mat. At 5°C min -1 Heating at a rate of 100°C and calcining at 550°C for 2 hours.

9. The preparation method of the novel anion exchange membrane photoelectrocatalytic water splitting hydrogen production reactor according to claim 6, characterized in that, In step S1, the preparation of the FeCoNi cathode (4) includes: The mixed solution of FeNiCo, isopropanol, deionized water and FAA-3-SOLUT-10-EtOH was ultrasonically treated and then uniformly sprayed onto Ti fiber felt. The sprayed cathode was annealed and calcined to obtain FeCoNi cathode (4).

10. The method for preparing the novel anion exchange membrane photoelectrocatalytic water splitting hydrogen production reactor according to claim 6, characterized in that, The preparation of the anion exchange membrane (5) in step S2 includes: immersing the anion exchange membrane in KOH solution to convert it into hydroxide form, thereby obtaining the treated anion exchange membrane (5).

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