Photocatalytic hydrogen evolution device and preparation method thereof

Abstract

The invention discloses a photocatalytic hydrogen evolution device and a preparation method thereof, and belongs to the technical field of photocatalysis, and the preparation method comprises the following steps: growing a transition metal oxide on a conductive substrate to form a transition metal oxide semiconductor photocathode as a photocathode of the photocatalytic hydrogen evolution device; the metal-based electrode is used as a photo-anode; and the two electrodes are connected through a wire and are placed in the electrolyte, so that the photocatalytic hydrogen evolution device is constructed. According to the invention, a transition metal oxide semiconductor photocathode and metal-based photoanode series system is taken as a core, innovative design is realized by coupling primary battery self-driven discharge and optical excitation process, and all-weather efficient photocatalytic hydrogen evolution can be realized without an external power supply. The device has remarkable advantages in the aspects of photon-generated carrier separation efficiency, photocatalytic hydrogen production efficiency and stability. The raw materials of the transition metal oxide semiconductor photocathode are easy to obtain and low in cost, the preparation process is simple and convenient, the operation is easy to master, and the method is suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the field of photocatalytic hydrogen evolution technology, and more specifically, to a high-efficiency photocatalytic hydrogen evolution device based on a series structure of a transition metal oxide semiconductor photocathode and a metal-based photoanode, and a preparation method thereof, which is suitable for the field of solar-driven water decomposition to produce hydrogen and clean energy development. Background Art

[0002] Solar-powered water-splitting hydrogen production technology is considered a key development direction for future green energy systems due to its potential to mitigate global warming and achieve a sustainable, all-weather energy supply. Using photocatalytic devices to decompose water into hydrogen using sunlight converts solar photon energy into hydrogen energy. Furthermore, hydrogen, due to its high energy density, renewability, and zero carbon emissions, is considered an ideal energy carrier to replace fossil fuels, offering significant potential for alleviating energy crises and environmental pollution.

[0003] Currently, the most efficient solar hydrogen production solution combines solar cells with electrolysis systems. A photoelectrochemical cell (PEC) is a device that directly utilizes solar light to produce hydrogen by splitting water. These cells typically employ a dual-photoelectrode structure, with an n-type semiconductor serving as the photoanode and a p-type semiconductor serving as the photocathode. For example, patents CN117552039A, "A tandem photoelectrochemical water splitting hydrogen production device based on a bismuth vanadate photoanode and a silver antimony sulfide photocathode," and CN115074746A, "A method for unbiased photoelectrocatalytic complete water splitting using an organic-inorganic semiconductor hybrid," both utilize an n-type semiconductor as the photoanode and a p-type semiconductor as the photocathode. This structure operates without an applied voltage. Under illumination, photogenerated electron-hole pairs are generated, generating a photocurrent and voltage that drive redox reactions of water molecules at the positive and negative electrodes, producing hydrogen and oxygen, thereby converting solar energy into chemical energy.

[0004] However, the practical application of the above-mentioned dual-photoelectrode structure photoelectrochemical cells still faces many technical bottlenecks. First, the development of p-type photocathode materials is seriously lagging behind, and the catalytic activity and stability of existing materials are difficult to meet actual needs. Second, the band structures of the n-type photoanode and p-type photocathode must be precisely matched, which places extremely high demands on material selection and device design. More importantly, the operation of such devices is completely dependent on light conditions. In low-light or no-light environments, hydrogen production cannot be sustained, which seriously limits their practical application. Summary of the Invention

[0005] In light of this, the present invention provides a photocatalytic hydrogen evolution device and its fabrication method. Based on the self-driven mechanism of a galvanic cell, the device features a series system consisting of a transition metal oxide semiconductor electrode as a photocathode and a metal-based electrode as a photoanode. By coupling the self-driven discharge process of the galvanic cell with the photoexcitation process, this device achieves efficient, all-weather photocatalytic hydrogen evolution without the need for an external power source. This design not only significantly improves the separation efficiency of photogenerated carriers, but also optimizes the overall efficiency of photocatalytic hydrogen production and ensures the long-term stability of the device.

[0006] To this end, the present invention provides the following technical solutions: In one aspect, the present invention provides a photocatalytic hydrogen evolution device, comprising: a primary cell and a reaction cell; the primary cell comprises: a transition metal oxide semiconductor electrode and a metal-based electrode connected by wires; wherein the transition metal oxide semiconductor electrode serves as a photocathode, and the metal-based electrode serves as a photoanode; The reaction cell is an electrolytic cell; the primary cell is placed in the electrolyte in the electrolytic cell to obtain a photocatalytic hydrogen evolution device.

[0007] Furthermore, the transition metal oxide semiconductor electrode includes: a conductive substrate and a transition metal oxide semiconductor.

[0008] Furthermore, the conductive substrate is fluorine-doped tin dioxide transparent conductive glass, indium tin oxide coated transparent conductive glass, aluminum-doped zinc oxide transparent conductive glass, carbon cloth or nickel foam.

[0009] Furthermore, the transition metal oxide semiconductor is nickel oxide, ferric oxide, cuprous oxide or manganese dioxide. Furthermore, the metal-based electrode sheet is a zinc-based electrode, an iron-based electrode, a cadmium-based electrode, a copper-based electrode or a nickel-based electrode.

[0010] In another aspect, the present invention further provides a method for preparing the above-mentioned photocatalytic hydrogen evolution device, comprising: preparing transition metal oxide semiconductor electrodes, metal-based electrodes and electrolytes; placing the electrolyte in an electrolytic cell, using the electrolytic cell as a reaction cell, using the prepared transition metal oxide semiconductor electrode as a photocathode, and using the metal-based electrode as a photoanode; The two electrodes are connected via a wire to form a primary cell; the primary cell is placed in an electrolyte to obtain a photocatalytic hydrogen evolution device.

[0011] Furthermore, it also includes: using a light source to irradiate the photocathode; the light source is sunlight, simulated sunlight or LED 365nm ultraviolet light.

[0012] Furthermore, preparing the electrolyte includes: mixing deionized water, potassium hydroxide, and a transition metal salt to obtain a mixed solution; The mixed solution was magnetically stirred to obtain a transparent clear solution, which was then cooled to room temperature to prepare an electrolyte.

[0013] Furthermore, preparing a transition metal oxide semiconductor electrode comprises: Pre-treating the conductive substrate, the pre-treatment comprising: ultrasonically cleaning the conductive substrate with toluene, acetone, anhydrous ethanol and deionized water in sequence, and then drying the conductive substrate in a vacuum drying oven; A transition metal oxide semiconductor precursor solution is prepared, and a conductive substrate is placed in the transition metal oxide semiconductor precursor solution. After impregnation, hydrothermal treatment, electrodeposition or high-temperature calcination, a transition metal oxide is obtained and grown on the conductive substrate to form a transition metal oxide semiconductor electrode.

[0014] Furthermore, the metal-based electrode is prepared, comprising: Take a metal-based electrode sheet, polish and cut it, soak the cut electrode sheet in an acid solution for a first preset time, take it out and soak it in deionized water for a second preset time, then transfer it to an electrolyte and soak it for a third preset time, then take it out, and finally place it in a vacuum drying oven to dry it to obtain a metal-based electrode sheet.

[0015] This invention establishes a novel theoretical framework for self-driven photocatalytic systems, demonstrating that photoelectric synergy can simultaneously overcome the dual limitations of carrier recombination and reaction kinetics. This provides a new methodology for developing all-weather renewable energy conversion technologies and plays a significant role in promoting the practical application of clean energy storage technologies. Compared with existing solar hydrogen production technologies based on photoelectrochemical cells, this invention has the following advantages: (1) Built-in electric field drives carrier separation: The primary cell (with a transition metal oxide semiconductor electrode as the photocathode and a metal-based electrode as the photoanode) generates a built-in electric field through self-driven electrochemical discharge, which can improve the carrier separation efficiency without the need for an external power supply. This means that as long as a primary cell can be formed (even if the potential difference is weak), a built-in electric field can be generated. Compared with photoelectrochemical cells, metal-based electrode photoanodes are easier to prepare than n-type photoanodes and do not need to consider energy level matching with p-type photocathodes.

[0016] (2) Enhanced hydrogen evolution by directional transfer of photogenerated charges: The electron-hole pairs generated by the photocathode of the transition metal oxide semiconductor electrode under light excitation are directional transferred along the energy band gradient under the control of the built-in electric field, which significantly improves the charge separation efficiency and thus greatly enhances the photocatalytic hydrogen evolution performance. Its efficiency is significantly better than that of traditional photoelectrochemical cells.

[0017] (3) All-weather continuous operation capability: The metal-based electrode as the negative electrode has the characteristics of high electrochemical capacity, which ensures that the system can still produce hydrogen through a continuous electrocatalytic process under dark conditions, achieving all-weather continuous operation. In contrast, photoelectrochemical cells can only be driven by solar energy and cannot achieve all-weather hydrogen evolution. The present invention can better meet practical application needs. BRIEF DESCRIPTION OF THE DRAWINGS 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 some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0018] Figure 1 The XRD pattern of the NiO-based transition metal oxide semiconductor electrode prepared in Example 1 of the present invention compared with a standard card; Figure 2 This is a cross-sectional scanning electron microscope image of the NiO-based transition metal oxide semiconductor electrode prepared in Example 1 of the present invention; Figure 3 This is a transmission electron microscope image of the NiO-based transition metal oxide semiconductor electrode prepared in Example 1 of the present invention; Figure 4 The X-ray photoelectron spectrum of the NiO-based transition metal oxide semiconductor electrode prepared in Example 1 of the present invention, a is the Ni 2p high-resolution X-ray photoelectron spectrum, and b is the O 1s high-resolution X-ray photoelectron spectrum; Figure 5 The band gap diagram of the NiO-based transition metal oxide semiconductor electrode prepared in Example 1 of the present invention, a is a solid ultraviolet diffuse reflectance spectrum diagram, and b is the corresponding Tauc diagram; Figure 6 This is a Mott-Schottky plot of the NiO-based transition metal oxide semiconductor electrode prepared in Example 1 of the present invention; Figure 7 The catalytic mechanism of the NiO / Zn photocatalytic hydrogen evolution device prepared in Example 1 of the present invention in the dark; Figure 8 The catalytic mechanism of the NiO / Zn photocatalytic hydrogen evolution device prepared in Example 1 of the present invention under light irradiation; Figure 9 The hydrogen evolution amount of the NiO / Zn photocatalytic hydrogen evolution device prepared in Example 1 of the present invention under no light, simulated sunlight and ultraviolet light irradiation; Figure 10The XRD pattern of the α-Fe2O3-based transition metal oxide semiconductor electrode prepared in Example 4 of the present invention compared with a standard card; Figure 11 The amount of hydrogen released by the α-Fe2O3 / Zn photocatalytic hydrogen evolution device prepared in Example 4 of the present invention under no light and simulated sunlight; Figure 12 The amount of hydrogen released by the Cu2O / Zn photocatalytic hydrogen evolution device prepared in Example 5 of the present invention under no light and simulated sunlight.

[0019] Figure 13 The hydrogen evolution amount of the MnO2 / Zn photocatalytic hydrogen evolution device prepared in Example 6 of the present invention under no light and simulated sunlight. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described 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 should fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0022] Based on thermodynamic analysis, the Gibbs free energy change (ΔG° = 237.2 kJ / mol) for the water splitting reaction corresponds to a theoretical decomposition potential (E°) of 1.23 V (vs. RHE). Conventional photocatalytic systems struggle to overcome this thermodynamic barrier due to inefficient carrier separation. To address this challenge, the inventors discovered that an electrochemically assisted strategy offers an innovative solution: constructing a galvanic cell with an open-circuit voltage of up to 1.5-2.0 V, significantly higher than E°. This approach enables simultaneous hydrogen and oxygen evolution reactions (HER and OER), while utilizing the cell's built-in electric field to spatially separate photogenerated carriers, thereby addressing recombination losses and sluggish surface kinetics. This allows for simultaneous driving of both the HER and OER reactions. Therefore, coupling the cell's built-in electric field with the photoexcitation process allows for the directed transfer of photogenerated electrons and holes along the electric field, suppressing recombination and accelerating surface redox kinetics, thus breaking through the efficiency bottleneck.

[0023] The present invention is described in detail below in conjunction with specific embodiments: Example 1 This embodiment provides a photocatalytic hydrogen evolution device, comprising: a primary cell and a reaction cell; the primary cell comprises a NiO-based transition metal oxide semiconductor electrode and a metal-based electrode connected by wires; the transition metal oxide semiconductor electrode serves as a photocathode, and the metal-based electrode serves as a photoanode; the reaction cell is an electrolytic cell; the primary cell is placed in an electrolyte within the electrolytic cell to obtain the photocatalytic hydrogen evolution device. By coupling the primary cell's self-driven discharge process with a light excitation process, efficient photocatalytic hydrogen evolution is achieved around the clock.

[0024] Accordingly, this embodiment also provides a method for preparing the above-mentioned photocatalytic hydrogen evolution device, which specifically includes the following steps: S11. Prepare a NiO-based transition metal oxide semiconductor electrode.

[0025] Specifically: S111. Pretreat the conductive substrate: Measure 50 mL each of toluene, acetone, anhydrous ethanol, and deionized water. Ultrasonic clean a 1 cm × 3 cm conductive substrate (FTO, Fluorine-doped Tin Oxide) using toluene, acetone, ethanol, and deionized water, sequentially. Each ultrasonic cleaning step lasts 30 minutes at a frequency of 300 W and a temperature of 25°C. After ultrasonic cleaning, dry the substrate in a vacuum drying oven at 60°C for 12 hours until ready for use.

[0026] S112. Preparation of transition metal oxide semiconductor precursor solution: First, weigh 16.5 g of NiSO4·6H2O and 2 g of K2S2O8, dissolve them in 200 mL of deionized water, and stir magnetically at 500 rpm for 10 min to obtain a green clear solution. Then, add 6 mL of ammonia water to the mixed solution and stir magnetically at 250 rpm for 1 h to obtain a dark green solution.

[0027] S113. Preparation of transition metal oxide semiconductor electrode: Transfer the transition metal oxide semiconductor precursor solution to a 500 mL beaker and place the FTO face up in parallel until the transition metal oxide precursor solution submerges the FTO. Immerse for 1 h while magnetically stirring at a speed of 500 rpm. After the reaction is completed, take out the FTO and rinse it three times with deionized water to obtain FTO loaded with light brown NiOOH. Then place it flat in a tube furnace and heat it to 200 °C at a heating rate of 2 °C / min under a nitrogen atmosphere and hold it for 1.5 h. After cooling to room temperature, a NiO-based transition metal oxide semiconductor electrode can be obtained.

[0028] The structure characterization and performance testing of the prepared transition metal oxide semiconductor electrode were carried out, and the results are as follows: Depend on Figure 1 It can be seen that the transition metal oxide semiconductor electrode in the present invention is composed of a NiO thin film. By comparing it with the two standard charts in the figure below, a diffraction peak appears at 37.5° in the upper spectrum, which is consistent with the NiO standard chart (JCPDS PDF No. 73-1519), proving that this example has produced a NiO transition metal oxide semiconductor electrode.

[0029] Depend on Figure 2 It can be seen that the NiO film grows flat on the FTO and is evenly distributed. Figure 3 It can be seen that the width of the NiO film is about 150 nm and the length is about 250 nm, indicating that the NiO transition metal oxide semiconductor electrode is composed of a NiO film.

[0030] Depend on Figure 4 a and Figure 4 b Analysis shows that the prepared NiO transition metal oxide electrode has Ni 2p peaks, and the characteristic peaks correspond to Ni 3+ and Ni 2+ , Ni 3+The 1s peak of O has three characteristic peaks, corresponding to lattice oxygen, oxygen vacancies, and adsorbed oxygen, with oxygen vacancies accounting for 76.3%. This indicates that the synthesized NiO electrode is more susceptible to electron capture, which is conducive to optimizing the electronic structure, enriching active sites, and efficient charge transfer at the interface. Depend on Figure 5 a and Figure 5 From b, we can see that NiO transition metal oxide electrode has absorption in the range of 200 nm-800 nm, especially strong absorption in the range of 200 nm-350 nm. According to the Tauc plot (a method for calculating the optical band gap of semiconductors) corresponding to the solid ultraviolet spectrum, we can calculate that the band gap of NiO material is 3.71 eV. Figure 6 It can be calculated that the Fermi level of the NiO transition metal oxide semiconductor electrode is 0.61 V vs. NHE, and thus the valence band position is calculated to be 0.81 V vs. NHE; combined with Figure 5 , the conduction band position is obtained to be -2.9 V vs. NHE, which means the band structure of NiO transition metal oxide semiconductor electrode is obtained.

[0031] S12, preparing a metal-based electrode; Specifically, a 0.2 mm thick zinc-based, iron-based, cadmium-based, copper-based, or nickel-based electrode was selected. It was polished using a grinder with 240-grit sandpaper for 10 minutes and then cut into a 1 cm × 3 cm rectangle. The electrode sheet was first immersed in a 2% HCl solution for 10 seconds, then removed and immersed in deionized water for 10 seconds. It was then transferred to an electrolyte solution and immersed for 10 seconds. Finally, it was dried in a vacuum oven at 60°C for 10 minutes to produce a metal-based electrode sheet.

[0032] S13, preparing an electrolyte; Specifically, 50 mL of deionized water, 8.42 g of potassium hydroxide, and 548.78 mg of zinc acetate dihydrate were weighed, and the deionized water, potassium hydroxide, and zinc acetate dihydrate were mixed to obtain a mixed solution; the mixed solution was magnetically stirred for 1 h at a speed of 500 rpm to obtain a transparent clear solution, which was cooled to room temperature to prepare an electrolyte.

[0033] S14. The prepared NiO-based transition metal oxide semiconductor electrode is used as the photocathode of the photocatalytic hydrogen evolution device, and the metal-based electrode is used as the photoanode. The two electrodes are connected by a wire and placed in an electrolyte to obtain a photocatalytic hydrogen evolution device.

[0034] When utilizing the above-mentioned photocatalytic hydrogen evolution device for hydrogen evolution, a light source may be used to illuminate the photocathode to achieve hydrogen evolution; the light source selected may be sunlight, simulated sunlight, or LED 365nm ultraviolet light. Hydrogen evolution can also be achieved in a dark environment.

[0035] The performance of a prepared photocatalytic hydrogen evolution device was tested, and the results are as follows: Figure 7 It is the catalytic mechanism of the photocatalytic hydrogen evolution device assembled by transition metal oxide semiconductor electrode, metal-based electrode and electrolyte in the dark state. Figure 6 The Fermi level (E F ) is 0.61 V vs. NHE, and the standard electrode potential (E0) of Zn in alkaline electrolyte is -1.26 V vs. NHE. Due to the potential difference, the two electrodes spontaneously discharge when connected in series. Even without a power source, electrons can spontaneously migrate from the Zn-based electrode to the NiO-based transition metal oxide semiconductor electrode, participating in the reduction reaction on the electrode surface.

[0036] Figure 8 This is the catalytic mechanism of photocatalytic hydrogen evolution devices assembled from transition metal oxide semiconductor electrodes, metal-based electrodes, and electrolytes under illumination. A NiO photocathode and a Zn photoanode connected in series can form a built-in electric field through electrochemical spontaneous discharge, promoting carrier separation without the need for an external power source. Electron-hole pairs generated by the NiO photocathode under illumination are regulated by the electric field and migrate directionally along the energy band gradient, significantly improving charge separation efficiency and further enabling efficient photocatalytic hydrogen evolution.

[0037] Depend on Figure 9 It can be seen that in the dark, the hydrogen evolution performance of the device is 68 μmol / h; under simulated sunlight, the hydrogen evolution performance is 115 μmol / h; under ultraviolet light, the hydrogen evolution performance is 277 μmol / h. The amount of hydrogen evolution under simulated light is twice that in the dark, and under ultraviolet light is three times that in the dark.

[0038] It can be seen that the present invention connects the transition metal oxide semiconductor photocathode and the metal-based photoanode in series through reasonable design, and realizes innovative design by coupling the self-driven discharge of the primary cell with the light excitation process, so that all-weather efficient photocatalytic hydrogen evolution can be achieved without an external power supply. This design not only significantly improves the separation efficiency of photogenerated carriers, but also optimizes the overall efficiency of photocatalytic hydrogen production and ensures the long-term stability of the device. Therefore, the device successfully solves the problems of high recombination rate of photogenerated carriers and slow surface catalytic kinetics in existing photocatalytic hydrogen production technologies, showing significant technical advantages and application prospects. In addition, the raw materials used in the preparation method of the transition metal oxide semiconductor electrode of the present invention are easy to obtain and low in cost. At the same time, the preparation process is simple, the operation is easy to master, and it is suitable for large-scale production.

[0039] Example 2 This embodiment provides a photocatalytic hydrogen evolution device. Similar to Example 1, this photocatalytic hydrogen evolution device also uses a NiO-based transition metal oxide semiconductor electrode. Unlike Example 1, this embodiment provides another method for preparing a photocatalytic hydrogen evolution device, specifically comprising the following steps: S21, preparing a NiO-based transition metal oxide semiconductor electrode; The specific steps include: S211. Pretreat the conductive substrate: Measure 50 mL each of toluene, acetone, anhydrous ethanol, and deionized water, and ultrasonically clean a 1 cm × 3 cm area of ​​FTO with toluene, acetone, ethanol, and deionized water, sequentially. Each ultrasonic cleaning step lasts 30 minutes at a frequency of 300 W and a temperature of 25°C. After ultrasonic cleaning, dry the substrate in a vacuum drying oven at 60°C for 12 hours before use. FTO is commercially available and not further processed.

[0040] S212. Preparation of transition metal oxide semiconductor precursor solution: First, weigh 15 g NiSO4·6H2O and 1.5 g K2S2O8, dissolve them in 200 mL of deionized water, and stir magnetically for 10 min at 500 rpm to obtain a green clear solution. Then, add 5 mL of ammonia water to the mixed solution and stir magnetically for 0.5 h at 250 rpm to obtain a dark green solution.

[0041] S213. Preparation of transition metal oxide semiconductor electrode: Transfer the transition metal oxide semiconductor precursor solution to a 500 mL beaker and place the FTO face up in parallel until the transition metal oxide precursor solution submerges the FTO. Immerse for 0.5 h while magnetically stirring at 500 rpm. After the reaction is completed, take out the FTO and rinse it three times with deionized water to obtain FTO loaded with light brown NiOOH. Then place it flat in a tube furnace and heat it to 200 °C at a heating rate of 2 °C / min under a nitrogen atmosphere and hold it for 1 h. After cooling to room temperature, a NiO-based transition metal oxide semiconductor electrode can be obtained.

[0042] S22, preparing a metal-based electrode; Select a 0.2 mm thick zinc-based, iron-based, cadmium-based, copper-based, or nickel-based electrode. Polish it with 240-grit sandpaper for 10 minutes and cut it into a 1 cm × 3 cm rectangle. Soak the electrode in a 1% HCl solution for 5 seconds, remove it, soak it in deionized water for 5 seconds, then transfer it to the electrolyte solution and soak it for 5 seconds. Finally, dry it in a vacuum oven at 60°C for 5 minutes to produce the metal-based electrode.

[0043] S23, preparing an electrolyte; 50 mL of deionized water, 7.08 g of potassium hydroxide, and 555 mg of zinc acetate dihydrate were weighed and mixed to obtain a mixed solution. The mixed solution was magnetically stirred at 500 rpm for 1 h to obtain a transparent clear solution, which was then cooled to room temperature to obtain an electrolyte.

[0044] S24. The prepared NiO-based transition metal oxide semiconductor electrode is used as the photocathode of the photocatalytic hydrogen evolution device, and the metal-based electrode is used as the photoanode. The two electrodes are connected by a wire and placed in an electrolyte to obtain a photocatalytic hydrogen evolution device.

[0045] Example 3 This embodiment provides a photocatalytic hydrogen evolution device. Similar to Example 1, this photocatalytic hydrogen evolution device also uses a NiO-based transition metal oxide semiconductor electrode. Unlike Example 1, this embodiment provides another method for preparing a photocatalytic hydrogen evolution device, specifically comprising the following steps: S31, preparing a NiO-based transition metal oxide semiconductor electrode; The specific steps include: S311. Pretreat the conductive substrate: Measure 50 mL each of toluene, acetone, anhydrous ethanol, and deionized water. Ultrasonic clean a 1 cm × 3 cm FTO substrate using toluene, acetone, ethanol, and deionized water, sequentially. Each ultrasonic cleaning step lasts 30 minutes at a frequency of 300 W and a temperature of 25°C. After ultrasonic cleaning, dry the substrate in a vacuum drying oven at 60°C for 12 hours until ready for use.

[0046] S312. Preparation of transition metal oxide semiconductor precursor solution: First, weigh 18 g NiSO4·6H2O and 2.5 g K2S2O8, dissolve them in 200 mL of deionized water, and stir magnetically for 10 min at 500 rpm to obtain a green clear solution. Then, add 7 mL of ammonia water to the mixed solution and stir magnetically for 1.5 h at 250 rpm to obtain a dark green solution.

[0047] S313. Preparation of transition metal oxide semiconductor electrode: Transfer the transition metal oxide semiconductor precursor solution to a 500 mL beaker and place the FTO face up in parallel until the transition metal oxide precursor solution submerges the FTO. Immerse for 1.5 h while magnetically stirring at 500 rpm. After the reaction is completed, take out the FTO and rinse it three times with deionized water to obtain FTO loaded with light brown NiOOH. Then place it flat in a tube furnace and heat it to 200 °C at a heating rate of 2 °C / min under a nitrogen atmosphere and hold it for 2 h. After cooling to room temperature, a NiO transition metal oxide semiconductor electrode can be obtained.

[0048] S32, preparing a metal-based electrode; Select a 0.2 mm thick zinc-based, iron-based, cadmium-based, copper-based, or nickel-based electrode. Polish it with 240-grit sandpaper for 10 minutes and cut it into a 1 cm × 3 cm rectangle. Soak the electrode in a 3% HCl solution for 15 seconds, remove it, soak it in deionized water for 15 seconds, then transfer it to the electrolyte solution and soak it for 15 seconds. Finally, dry it in a vacuum oven at 60°C for 15 minutes to produce the metal-based electrode.

[0049] S33, preparing an electrolyte; 50 mL of deionized water, 9.2 g of potassium hydroxide, and 508 mg of zinc acetate dihydrate were weighed and mixed to obtain a mixed solution. The mixed solution was magnetically stirred at 500 rpm for 1 h to obtain a transparent clear solution, which was then cooled to room temperature to obtain an electrolyte.

[0050] S34. The prepared NiO-based transition metal oxide semiconductor electrode is used as the photocathode of the photocatalytic hydrogen evolution device, and the metal-based electrode is used as the photoanode. The two electrodes are connected by a wire and placed in an electrolyte to obtain a photocatalytic hydrogen evolution device.

[0051] Example 4 This embodiment provides a photocatalytic hydrogen evolution device, comprising: a primary cell and a reaction cell; the primary cell comprises an α-Fe2O3-based transition metal oxide semiconductor electrode and a metal-based electrode connected by wires; the transition metal oxide semiconductor electrode serves as a photocathode, and the metal-based electrode serves as a photoanode; the reaction cell is an electrolytic cell; the primary cell is placed in an electrolyte within the electrolytic cell to obtain the photocatalytic hydrogen evolution device. By coupling the primary cell's self-driven discharge process with a light excitation process, efficient photocatalytic hydrogen evolution is achieved around the clock.

[0052] Accordingly, this embodiment also provides specific steps for preparing an α-Fe2O3-based transition metal oxide semiconductor electrode, including: S411. Pretreat the conductive substrate: Measure 50 mL each of toluene, acetone, anhydrous ethanol, and deionized water. Ultrasonic clean a 1 cm × 3 cm FTO substrate using toluene, acetone, ethanol, and deionized water, sequentially. Each ultrasonic cleaning step lasts 30 minutes at a frequency of 300 W and a temperature of 25°C. After ultrasonic cleaning, dry the substrate in a vacuum drying oven at 60°C for 12 hours until ready for use.

[0053] S412. Preparation of transition metal oxide semiconductor precursor solution: Weigh 1.62 g FeCl3·6H2O and 0.36 g CO(NH2)2 respectively, dissolve them in 40 mL of deionized water, and stir magnetically for 30 min.

[0054] S413. Preparation of transition metal oxide semiconductor electrode: transfer the transition metal oxide semiconductor precursor solution into a reactor, and place FTO vertically until the photoactive material precursor solution submerges 1 / 3 of the length of the FTO, heat it to 100 °C and maintain it for 11 h; wait for the reactor to cool naturally to room temperature, take it out and rinse it repeatedly with deionized water and anhydrous ethanol three times to obtain FTO loaded with yellow FeOOH, then place it flat in a muffle furnace, heat it to 550 °C and maintain it for 2 h, then continue to heat it to 700 °C and maintain it for 15 min, and wait for it to cool to room temperature to obtain an α-Fe2O3-based transition metal oxide semiconductor electrode.

[0055] The structure characterization and performance testing of the prepared transition metal oxide semiconductor electrode were carried out, and the results are as follows: Depend on Figure 10It can be seen that the transition metal oxide semiconductor electrode in the present invention is composed of α-Fe2O3 nanoarrays. By comparing it with the two standard charts in the lower part of the figure, the upper spectrum shows two diffraction peaks at 35.8° and 64.2°, which are consistent with the standard chart of α-Fe2O3 (JCPDS PDF No. 06-0502), proving that this example has prepared an α-Fe2O3-based transition metal oxide semiconductor electrode.

[0056] The remaining steps of preparing the metal-based electrode, the electrolyte and obtaining the photocatalytic hydrogen evolution device are the same as S12 to S14 in Example 1 and are not described here in detail.

[0057] The performance of a prepared photocatalytic hydrogen evolution device was tested, and the results are as follows: Depend on Figure 11 It can be seen that in the dark, the hydrogen evolution performance of the device is 8 μmol / h; under simulated sunlight, the hydrogen evolution performance is 113 μmol / h; the amount of hydrogen evolved under simulated sunlight is 14 times that in the dark.

[0058] Example 5 This embodiment provides a photocatalytic hydrogen evolution device, comprising: a primary cell and a reaction cell; the primary cell comprises a Cu2O-based transition metal oxide semiconductor electrode and a metal-based electrode connected by wires; the transition metal oxide semiconductor electrode serves as a photocathode, and the metal-based electrode serves as a photoanode; the reaction cell is an electrolytic cell; the primary cell is placed in an electrolyte within the electrolytic cell to obtain the photocatalytic hydrogen evolution device. By coupling the primary cell's self-driven discharge process with a light excitation process, efficient, all-weather photocatalytic hydrogen evolution is achieved.

[0059] Accordingly, this embodiment also provides specific steps for preparing a Cu2O-based transition metal oxide semiconductor electrode, including: S511. Pretreat the conductive substrate: Measure 50 mL each of toluene, acetone, anhydrous ethanol, and deionized water and ultrasonically clean a 1 cm × 3 cm area of ​​FTO with toluene, acetone, ethanol, and deionized water, sequentially. Each ultrasonic cleaning step lasts 30 minutes at a frequency of 300 W and a temperature of 25°C. After ultrasonic cleaning, dry the substrate in a vacuum drying oven at 60°C for 12 hours before use. FTO is commercially available and not further processed.

[0060] S512. Preparation of transition metal oxide semiconductor precursor solution: Cu2O nanomaterials were prepared on the surface of conductive glass by simple electrodeposition. First, 3 mol / L lactic acid solution was added dropwise to 0.4 mol / L CuSO4∙5H2O solution. The solution was stirred continuously for 30 minutes until the solution turned bright blue. The pH of the deposition solution was adjusted to 10.0 using 4 mol / L NaOH solution to obtain the transition metal oxide semiconductor precursor solution.

[0061] S513. Preparation of transition metal oxide semiconductor electrodes: Electrodeposition was performed at a constant temperature of 60°C using conductive glass (FTO) as the cathode and a carbon rod as the anode at a voltage of 1.0 V for 10 min. After electrodeposition, the electrodeposited sample was rinsed three times with deionized water and dried for later use to obtain a Cu2O-based transition metal oxide semiconductor electrode.

[0062] The remaining steps of preparing the metal-based electrode, the electrolyte and obtaining the photocatalytic hydrogen evolution device are the same as S12 to S14 in Example 1 and are not described here in detail.

[0063] The performance of a prepared photocatalytic hydrogen evolution device was tested, and the results are as follows: Depend on Figure 12 It can be seen that in the dark, the hydrogen evolution performance of the device is 2 μmol / h; under simulated sunlight, the hydrogen evolution performance is 5 μmol / h; the amount of hydrogen evolved under simulated light is 2.5 times that in the dark.

[0064] Example 6 This embodiment provides a photocatalytic hydrogen evolution device, comprising: a primary cell and a reaction cell; the primary cell comprises: an MnO2-based transition metal oxide semiconductor electrode and a metal-based electrode connected by wires; the transition metal oxide semiconductor electrode serves as a photocathode, and the metal-based electrode serves as a photoanode; the reaction cell is an electrolytic cell; the primary cell is placed in an electrolyte within the electrolytic cell to obtain the photocatalytic hydrogen evolution device. By coupling the primary cell's self-driven discharge process with a light excitation process, efficient photocatalytic hydrogen evolution is achieved in all weather conditions.

[0065] Accordingly, this embodiment also provides specific steps for preparing a MnO2-based transition metal oxide semiconductor electrode, including: S611. Pretreat the conductive substrate: Measure 50 mL each of toluene, acetone, anhydrous ethanol, and deionized water. Ultrasonic clean a 1 cm × 3 cm area of ​​FTO with toluene, acetone, ethanol, and deionized water, sequentially. Each ultrasonic cleaning step lasts 30 minutes at a frequency of 300W and a temperature of 25°C. After ultrasonic cleaning, dry the substrate in a vacuum drying oven at 60°C for 12 hours before use. FTO is commercially available and not further processed.

[0066] S612. Preparation of transition metal oxide semiconductor precursor solution: Weigh 79 mg of KMnO4 and dissolve it in 50 mL of deionized water. Stir thoroughly for about 30 minutes to allow it to fully dissolve and form a uniform solution.

[0067] S613. Preparation of a transition metal oxide semiconductor electrode: Transfer the transition metal oxide semiconductor precursor solution to a reactor and place the FTO film vertically until the photoactive material precursor solution submerges one-third of the FTO length, ensuring that the conductive surface faces the inner wall of the autoclave. Finally, add 4 mL of the prepared solution to the autoclave and maintain it at 110°C for 7 hours. After the reaction is complete, remove the conductive glass, rinse it three times with distilled water, and dry it in an oven at 60°C for 2 hours. Remove and set aside to obtain a MnO2-based transition metal oxide semiconductor electrode.

[0068] The remaining steps of preparing the metal-based electrode, the electrolyte and obtaining the photocatalytic hydrogen evolution device are the same as S12 to S14 in Example 1 and are not described here in detail.

[0069] The performance of a prepared photocatalytic hydrogen evolution device was tested, and the results are as follows: Depend on Figure 13 It can be seen that in the dark, the hydrogen evolution performance of the device is 0.28 μmol / h; under simulated sunlight, the hydrogen evolution performance is 0.82 μmol / h; the amount of hydrogen evolved under simulated light is 2.9 times that in the dark.

[0070] In the above embodiment, with a transition metal oxide semiconductor photocathode and a metal-based photoanode in series as the core, an innovative design is achieved by coupling the self-driven discharge of the primary cell with the light excitation process, and efficient photocatalytic hydrogen evolution can be achieved all day and night without an external power supply. This design not only significantly improves the separation efficiency of photogenerated carriers, but also optimizes the overall efficiency of photocatalytic hydrogen production and ensures the long-term stability of the device. Therefore, the device successfully solves the problems of high photogenerated carrier recombination rate and slow surface catalytic kinetics in existing photocatalytic hydrogen production technologies, showing significant technical advantages and application prospects.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A photocatalytic hydrogen evolution device, characterized in that: include: A primary cell and a reaction cell; the primary cell comprises: a transition metal oxide semiconductor electrode and a metal-based electrode connected by wires; wherein the transition metal oxide semiconductor electrode serves as a photocathode and the metal-based electrode serves as a photoanode; The reaction cell is an electrolytic cell; the primary cell is placed in the electrolyte in the electrolytic cell to obtain a photocatalytic hydrogen evolution device.

2. A photocatalytic hydrogen evolution device according to claim 1, characterized in that: The transition metal oxide semiconductor electrode includes a conductive substrate and a transition metal oxide semiconductor.

3. A photocatalytic hydrogen evolution device according to claim 2, characterized in that: The conductive substrate is fluorine-doped tin dioxide transparent conductive glass, indium tin oxide coated transparent conductive glass, aluminum-doped zinc oxide transparent conductive glass, carbon cloth or foamed nickel.

4. A photocatalytic hydrogen evolution device according to claim 2, characterized in that: The transition metal oxide semiconductor is nickel oxide, ferric oxide, cuprous oxide or manganese dioxide.

5. The photocatalytic hydrogen evolution device according to claim 1, characterized in that: The metal-based electrode sheet is a zinc-based electrode, an iron-based electrode, a cadmium-based electrode, a copper-based electrode or a nickel-based electrode.

6. A method for preparing a photocatalytic hydrogen evolution device according to any one of claims 1 to 5, characterized in that: include: preparing transition metal oxide semiconductor electrodes, metal-based electrodes and electrolytes; placing the electrolyte in an electrolytic cell, using the electrolytic cell as a reaction cell, using the prepared transition metal oxide semiconductor electrode as a photocathode, and using the metal-based electrode as a photoanode; The two electrodes are connected via a wire to form a primary cell; the primary cell is placed in an electrolyte to obtain a photocatalytic hydrogen evolution device.

7. The preparation method according to claim 6, wherein Also includes: The photocathode is irradiated with a light source; the light source is sunlight, simulated sunlight or LED 365nm ultraviolet light.

8. The preparation method according to claim 6, characterized in that Preparation of the electrolyte includes: mixing deionized water, potassium hydroxide, and a transition metal salt to obtain a mixed solution; The mixed solution was magnetically stirred to obtain a transparent clear solution, which was then cooled to room temperature to prepare an electrolyte.

9. The preparation method according to claim 6, characterized in that A transition metal oxide semiconductor electrode is prepared, comprising: Pre-treating the conductive substrate, the pre-treatment comprising: ultrasonically cleaning the conductive substrate with toluene, acetone, anhydrous ethanol and deionized water in sequence, and then drying the conductive substrate in a vacuum drying oven; A transition metal oxide semiconductor precursor solution is prepared, and a conductive substrate is placed in the transition metal oxide semiconductor precursor solution. After impregnation, hydrothermal treatment, electrodeposition or high-temperature calcination, a transition metal oxide is obtained and grown on the conductive substrate to form a transition metal oxide semiconductor electrode.

10. The preparation method according to claim 6, characterized in that Prepare metal-based electrodes, including: Take a metal-based electrode sheet, polish and cut it, soak the cut electrode sheet in an acid solution for a first preset time, take it out and soak it in deionized water for a second preset time, then transfer it to an electrolyte and soak it for a third preset time, then take it out, and finally place it in a vacuum drying oven to dry it to obtain a metal-based electrode sheet.

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