Gold-modified lanthanum ferrite-based semiconductor thin film photoelectrochemical water splitting photoanode and preparation method thereof

Abstract

The present application relates to a kind of gold modified lanthanum ferrite-based semiconductor thin film photoelectrochemical water splitting anode and its preparation method, for photoelectrochemical water splitting hydrogen production field.The photoanode includes transparent conductive substrate, wide band gap semiconductor layer on the conductive substrate, Au nanoparticle layer on the wide band gap semiconductor layer, LaFeO3 absorption layer on the Au nanoparticle layer.The application of p-type LaFeO3 semiconductor is applied to the construction of photoanode by the design of special structure, combined with wide band gap semiconductor TiO2 and the use of local surface plasmon effect of Au nanoparticle, the light absorption range of photoanode is expanded, the photocurrent density of photoanode is enhanced, the photoelectric conversion efficiency of photoanode is improved, and the overall light hydrogen production efficiency of electrode system is improved, which is of great significance.The preparation of the photoanode is simple and convenient, can be mass-produced, the raw material cost is low and environment-friendly, and is expected to be commercialized and applied in the field of photoelectrochemical water splitting.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photoelectrochemical water splitting for hydrogen production, in particular to an Au-modified LaFeO3-based semiconductor thin film photoanode for photoelectrochemical water splitting and a preparation method thereof. BACKGROUND

[0002] Hydrogen energy is pollution-free and has high energy density, and is the most promising emerging energy to replace traditional fossil energy. At present, the main methods for hydrogen production are fossil energy reform, electrolysis of water, biomass and photochemical water splitting. Fossil energy reform produces carbon dioxide emissions, which is not conducive to the realization of carbon neutralization. Electrolysis of water has high energy consumption and cost. Biomass hydrogen production still needs to be further improved. Photochemical water splitting directly uses solar energy and is a very promising pollution-free hydrogen production technology. Photoelectrocatalytic hydrogen production, as a key technology for photochemical water splitting, has obvious advantages among many hydrogen production methods. It can directly convert solar energy into chemical energy. The principle is to use the electron-hole pairs generated by the photoactive semiconductor under sunlight to load the carriers into the electrolyte for water splitting reaction under the assistance of an external bias. The external bias promotes electron migration using an electric field, which can hinder the recombination of photo-generated carriers, making it more efficient than pure photocatalysis.

[0003] In a conventional photoelectrocatalytic system, the most critical component is the working electrode, which generally uses an n-type semiconductor as a photoanode for oxygen production. The p-type semiconductor acts as a photocathode responsible for hydrogen production. Both photoelectrodes are extremely important, but the water oxidation reaction on the photoanode to produce oxygen is a relatively slow kinetic process and is the bottleneck step of the entire water splitting reaction. There are many choices for current photoanode materials. Metal oxides such as ZnO have good light absorption capacity and chemical stability, but they usually have low carrier mobility and narrow light absorption range. Carbon-based materials such as graphene and carbon nanotubes have good electrical conductivity and chemical stability, but they have poor light absorption efficiency. Semiconductor materials such as CdS have strong light absorption capacity, but they often have toxic and hazardous risks and are prone to photo-corrosion under light.

[0004] Perovskite materials are widely used in photoanodes because they have a wide range of light absorption, high carrier mobility, adjustable photoelectric properties, abundant raw materials, low cost, and long-term stability. LaFeO3 is a typical perovskite material, which has the above advantages. LaFeO3 is a p-type semiconductor with a band gap of 2.1-2.2 eV, which is a suitable band structure. LaFeO3-based photoanodes have a wide light absorption range, can effectively absorb visible light, and have good electron-hole separation and migration ability after light excitation, which helps to improve the photoelectric conversion efficiency. In addition, LaFeO3-based photoanodes have good light corrosion resistance, excellent redox stability and good electrochemical performance, which makes them have great development prospects in the field of photoelectrochemical water splitting. However, the performance of LaFeO3 single material is limited, and special structure design is needed to further improve its photoelectrochemical performance.

[0005] Thanks to the localized surface plasmon resonance (LSPR) effect, gold (Au) and other noble metal nanoparticles exhibit strong broadband light absorption characteristics in the visible light region. The free electrons near the surface of noble metal nanoparticles can undergo periodic oscillation under the driving of external electromagnetic field, which can localize light in the range of several nanometers around the metal nanoparticles, thereby enhancing the light absorption efficiency of the surrounding semiconductor. In addition, the localized electromagnetic field enhancement effect produced by noble metals can promote the band gap transition of the surrounding semiconductor, thereby generating more photoelectron-hole pairs. Under the driving of the localized electromagnetic field enhancement effect of noble metals, the rapid separation of photoelectron-hole pairs can be accelerated, thereby improving the photoelectric conversion efficiency of the photoelectrode.

[0006] Therefore, under the action of LSPR effect, the light absorption capacity of LaFeO3-based photoanode can be enhanced, the light absorption range can be expanded, and the photoelectric conversion efficiency can be improved through special structure design and Au nanoparticle modification. In addition, the preparation process of Au-modified LaFeO3-based photoanode is simple and convenient, and large-scale production can be realized. Although Au is expensive, the use cost of Au can be greatly reduced by using nanoscale amount and large-scale production, which is of great significance to the improvement of photoanode performance and the improvement of overall light-to-hydrogen efficiency of electrode system. SUMMARY

[0007] In view of the problems existing in the prior art, the present application aims to provide an Au-modified LaFeO3-based semiconductor thin film photoelectrochemical water splitting anode and a preparation method thereof. The photoanode selects LaFeO3 material as a main absorption layer, and a special structure of a TiO2 layer, an Au nanoparticle layer and a LaFeO3 absorption layer is sequentially constructed on a transparent conductive substrate, so that the photoanode with strong light absorption capacity, high photoelectric conversion efficiency and strong working stability is obtained. The photoanode is used as a working electrode of a three-electrode system, and the photoelectric conversion efficiency and stability of the whole electrode system under electrical assistance are further improved.

[0008] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0009] An Au-modified LaFeO3-based semiconductor thin film photoelectrochemical water splitting anode, the Au-modified LaFeO3-based photoanode comprises a transparent conductive substrate, a wide band gap semiconductor layer on the conductive substrate, an Au nanoparticle layer on the wide band gap semiconductor layer, and a LaFeO3 absorption layer on the Au nanoparticle layer, and the structure of the photoanode is LaFeO3 / Au / TiO2 / FTO. The structure of the Au-modified LaFeO3-based photoanode with improved performance is LaFeO3 / TiO2 / Au / TiO2 / FTO.

[0010] Further, the transparent conductive substrate is selected from FTO glass sheets.

[0011] Further, the wide band gap semiconductor layer is a TiO2 layer.

[0012] Further, the thickness of the wide band gap semiconductor layer is 400-600 nm.

[0013] Further, the thickness of the Au nanoparticle layer is 6 nm.

[0014] Further, the particle size of the Au nanoparticles is 15-50 nm.

[0015] Further, the LaFeO3 absorption layer is a double layer.

[0016] Further, the overall thickness of the LaFeO3 absorption layer is 400-600 nm.

[0017] Further, the Au-modified LaFeO3-based semiconductor thin film photoelectrochemical water splitting anode is used as a working electrode in a three-electrode system, and the electrode system further comprises an Ag / AgCl reference electrode, a Pt counter electrode and an electrochemical workstation, the electrochemical workstation provides a voltage source, and the working electrode, the reference electrode and the counter electrode are connected to the electrochemical workstation.

[0018] The application also provides a preparation method of an Au-modified LaFeO3-based semiconductor thin film photoelectrochemical water splitting photoanode, comprising the following steps:

[0019] Step one, growing a TiO2 thin film on FTO by using liquid deposition technology and annealing technology;

[0020] Step two, preparing an Au nanoparticle layer by using vacuum evaporation technology and annealing technology;

[0021] Step three, preparing a LaFeO3 thin film layer by using sol-gel spin coating and annealing technology.

[0022] In view of the technical problems existing in the prior art and the difficulty in solving the problems, the technical problems solved by the technical solution of the application and some creative technical effects brought after the problems are solved are analyzed in detail and profoundly in combination with the technical solution to be protected by the application and the results and data in the research and development process.The technical solution to be protected by the application has the following advantages and positive effects:

[0023] The Au-modified LaFeO3-based photoanode uses LaFeO3 material as an absorption layer, and a special-structure photoanode is constructed by sequentially layering and arranging a TiO2 layer, an Au nanoparticle layer and a LaFeO3 absorption layer on a transparent conductive substrate, so that the application of LaFeO3 material as a main absorption layer in the photoanode is realized.

[0024] The test method of the application utilizes the enhanced electromagnetic field of localized surface plasmons to improve the light absorption efficiency of the photoanode, increase the number of electron-hole pairs and realize the enhancement of the photocurrent density.

[0025] The method obtains high-quality Au nanoparticles with uniform particle size on a TiO2 thin film with adjustable thickness, utilizes the localized surface plasmons and enhanced electromagnetic field generated by the Au nanoparticles to improve the light absorption efficiency of the LaFeO3-based photoanode, expand the light absorption range and accelerate the separation of photo-generated electron-hole pairs, so that the photocurrent density and photoelectric conversion efficiency of the photoanode in the wavelength range of 500-700 nm are improved.

[0026] Compared with the prior art, the application has the following beneficial effects:

[0027] First, the Au-modified LaFeO3-based photoanode has higher light absorption efficiency, wider light absorption range and higher photoelectric conversion efficiency, which are described in detail as follows:

[0028] 1) The electron-hole separation and migration ability of LaFeO3 after light excitation is good, and the use of the material as an absorption layer of the photoanode helps to improve the photoelectric conversion efficiency;

[0029] 2) Due to the LSPR effect of Au nanoparticles, a locally enhanced electromagnetic field is generated, which promotes the separation of LaFeO3 carrier, thereby enhancing the photocurrent density and improving the photoelectric conversion efficiency;

[0030] 3) Au nanoparticles can be approximated as a converging antenna, which transfers the energy of incident light to the surrounding LaFeO3 absorption layer, thereby increasing the number of electron-hole pairs and enhancing the photocurrent density;

[0031] 4) The LSPR effect of Au nanoparticles is in the wavelength range of 500-700 nm, and the light absorption of LaFeO3 is almost non-existent in this range, which directly expands the overall light absorption range of the photoanode and enhances its photoelectric conversion efficiency in the wavelength range of 500-700 nm.

[0032] Secondly, the technical effect and advantages of the technical solution to be protected by the present application are described as follows:

[0033] 1) The preparation of Au-modified LaFeO3-based photoanode includes four preparation methods: liquid deposition, vacuum evaporation, spin coating and annealing, each of which is simple and convenient, and can realize large-scale production of photoanodes;

[0034] 2) The raw materials of Au-modified LaFeO3-based photoanode are low in price and easy to obtain except for Au. Although Au is expensive, the use cost of Au can be greatly reduced by using nanoscale amount and large-scale production, that is, the cost of photoanode can be further reduced once mass production is realized;

[0035] 3) The raw materials of Au-modified LaFeO3-based photoanode are environmentally friendly. Au and Ti are non-toxic to the environment, and elements La and Fe are generally relatively stable and not easy to release toxic ions, causing less harm to the environment and human health.

[0036] 4) Au-modified LaFeO3-based photoanode is corrosion-resistant and has strong chemical stability, and can be used for a long time.

[0037] Thirdly, the inventiveness of the claims of the present application is also reflected in the following important aspects:

[0038] 1) The technical solution of the present application fills the technical gap in the industry at home and abroad: due to the limitation of the number of photo-generated electron-hole pairs and the band gap of LaFeO3 material, the light absorption range and photoelectric conversion efficiency are limited. The addition of TiO2 thin film with wide band gap semiconductor expands the light absorption range of the photoanode, and the modification of Au particles further expands the light absorption range of the photoanode and improves the photocurrent density and photoelectric conversion efficiency of the photoanode by relying on the LSPR effect.

[0039] 2) The technical scheme of the present application overcomes the technical prejudice: the traditional photoanode generally selects n-type semiconductor material, but LaFeO3 is a P-type semiconductor, and still realizes the application in the field of photoanode, which has certain reference significance for the application of other p-type semiconductors in photoanode or the application of n-type semiconductors in photocathode. In addition, it is generally believed that Au and other noble metals are not suitable for production preparation due to their expensive price, but the actual small amount of use and mass production can control the cost lower. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained according to these drawings without creative labor for those skilled in the art.

[0041] Figure 1 is the flow chart of the preparation method of the Au-modified LaFeO3-based photoanode provided by the second embodiment of the present application with the best performance.

[0042] Figure 2 is the schematic diagram of the structure of the Au-modified LaFeO3-based photoanode provided by the second embodiment of the present application with the best performance.

[0043] Figure 3 is the scanning electron microscope (SEM) photo provided by the comparative example 1, the comparative example 2 and the comparative example 4 of the present application, and the energy spectrum analysis diagram of the comparative example 4.

[0044] Figure 4 is the ultraviolet absorption spectrum data diagram provided by the first embodiment and the second embodiment of the present application and the comparative example 1 and the comparative example 3.

[0045] Figure 5 is the on-off data diagram provided by the second embodiment, the first embodiment and the comparative example 1 of the present application from left to right.

[0046] Figure 6 is the photoelectric conversion efficiency (IPCE) data diagram provided by the second embodiment, the first embodiment and the comparative example 1 of the present application from top to bottom. DETAILED DESCRIPTION

[0047] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not intended to limit the present application. Based on the embodiments in the present application, other embodiments obtained by those skilled in the art without creative efforts fall within the scope of the present application. In the following embodiments, the experimental methods are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified.

[0048] Spatially relative terms such as "beneath", "below", "lower", "above", "upper", and the like, are used to describe an element's position relative to another element as illustrated in the figures. These terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

[0049] In addition, terms such as "first", "second", and the like are used to describe various elements, layers, regions, sections, and the like, and are not intended to be limiting. The use of "have", "has", "including", "including", "including", "including" and the like is an open term, indicating the presence of the stated element or feature, but not excluding additional elements or features. Unless the context clearly dictates otherwise.

[0050] The present application provides an Au-modified LaFeO3-based semiconductor thin film photoelectrochemical water splitting anode and a preparation method thereof. The present application provides two preferred embodiments, two comparative examples, and one test example, as follows.

[0051] Example 1: The working electrode of this embodiment is an Au-modified LaFeO3-based photoanode, which is prepared using the steps shown in Figure 1 The structure is as shown in Figure 2 The photoanode includes a transparent conductive substrate, a TiO2 layer on the transparent conductive substrate, an Au nanoparticle layer on the TiO2 layer, and a LaFeO3 absorption layer on the Au nanoparticle layer. The transparent conductive substrate is selected from FTO glass substrate. The TiO2 layer is disposed on the transparent conductive substrate with a thickness of 400-600 nm. The Au nanoparticle layer is disposed on the TiO2 layer with a thickness of 6 nm, and the Au nanoparticle has a particle size of 15-50 nm. The LaFeO3 absorption layer is disposed on the Au nanoparticle layer with a thickness of 400-600 nm.

[0052] In Example 1, the photoanode is used as the working electrode of a three-electrode system, which includes a working electrode, a reference electrode and a counter electrode. The reference electrode is selected from Ag / AgCl reference electrode, and the counter electrode is selected from Pt counter electrode.

[0053] In embodiment one, the electrode system further comprises an electrochemical workstation, the electrochemical workstation provides external bias for the electrode system, the working electrode, the reference electrode and the counter electrode are connected to the electrochemical workstation respectively. After the LaFeO3-based photoanode is irradiated by sunlight, electron-hole pairs are excited, the holes enter the electrolyte to carry out the oxygen evolution half-reaction under the joint action of the space electric field and the external bias, and the electrons are transferred to the Pt sheet counter electrode on the other side to participate in the hydrogen evolution half-reaction. In this process, the TiO2 layer plays a role in constructing a space electric field with the absorption layer to promote carrier separation, and the local surface plasmon effect generated by the Au nanoparticle layer further promotes the process: under irradiation, the local surface plasmon can enhance the local electromagnetic field intensity around the metal nanoparticles, thereby effectively improving the light absorption capacity, realizing the convergence of the local surface plasmon on light, and promoting the separation of carriers; more incident light can be absorbed in the electrode system to generate more electron-hole pairs, so that more photocurrent can be generated after the separation of the electron-hole pairs.

[0054] In combination with the above-mentioned Au-modified LaFeO3-based photoanode, embodiment one of the present application further provides a preparation method of the photoanode. Next, the preparation method will be introduced in detail.

[0055] The TiO2 layer is grown on the FTO glass substrate by using liquid deposition technology and annealing technology, a 0.2M ammonium fluorotitanate solution and a 0.4M boric acid solution are mixed according to a volume ratio of 1:1, the FTO glass is placed in the solution for 6h, and then the FTO glass is annealed at 500℃ for 5h by using a muffle furnace, so as to obtain a TiO2 thin film layer with a thickness of 400-600nm. The photoelectrode with a structure of TiO2 is obtained.

[0056] The Au nanoparticle layer is grown on the surface of the TiO2 thin film layer by using vacuum evaporation technology, an Au metal film layer with a thickness of 6nm is evaporated, annealing technology is used, the Au metal film layer is annealed at 500℃ for 30min by using a muffle furnace, so as to obtain an Au nanoparticle layer with a particle size of 15-50nm. The photoelectrode with a structure of Au / TiO2 is obtained.

[0057] The LaFe03absorbing layer was prepared by sol-gel spin coating method. 4 mmol of lanthanum nitrate hexahydrate, 4 mmol of iron nitrate nonahydrate and 8 mmol of citric acid monohydrate were dissolved in 10 ml of ethylene glycol monomethyl ether, stirred at 60°C for 2 hours, then aged for 24 hours, and the precursor solution was obtained after filtration through PTFE. The Au / Ti02photoelectrode was fixed on the chuck of the spin coater, and the precursor solution was added on the surface of the electrode, then spin coated at 500 r / min for 5 s and at 4000 r / min for 30 s to obtain a wet film. The wet film was baked at 200°C for 3 min and annealed at 600°C for 5 min to obtain a LaFe03thin film. In order to obtain a certain thickness of the film, the spin coating process was repeated twice, and then the film was annealed at 600°C for 2 h in a muffle furnace to obtain the LaFe03absorbing layer. A photoanode with the structure of LaFe03 / Au / Ti02was obtained.

[0058] Example 2: In this example, the photoelectrode was prepared and the electrode system was constructed according to the method of Example 1, except that the Au nanoparticle layer was inside the Ti02layer. The Ti02layer, which was originally deposited for 6 h, was deposited in two times, first for 5 h, then the Au nanoparticle layer was evaporated, and then the Ti02layer was deposited for 1 h. A photoanode with the structure of LaFe03 / Ti02 / Au / Ti02was obtained.

[0059] Comparative Example 1: In this comparative example, the photoelectrode was prepared and the electrode system was constructed according to the method of Example 1, except that the photoelectrode did not have an Au nanoparticle layer. A photoanode with the structure of LaFe03 / Ti02was obtained.

[0060] Comparative Example 2: In this comparative example, the photoelectrode was prepared and the electrode system was constructed according to the method of Example 1, except that the photoelectrode did not have a LaFe03absorbing layer. A photoanode with the structure of Au / Ti02was obtained.

[0061] Comparative Example 3: In this comparative example, the photoelectrode was prepared and the electrode system was constructed according to the method of Example 1, except that the photoelectrode only had a Ti02layer. A photoanode with the structure of Ti02was obtained.

[0062] Comparative Example 4: In this comparative example, the photoelectrode was prepared and the electrode system was constructed according to the method of Example 1, except that the photoelectrode only had a LaFe03absorbing layer. A photoanode with the structure of LaFe03was obtained.

[0063] Test Example:

[0064] On-off data test condition: the electrolyte solution used is 0.1 mol / L KOH solution, and the solution pH value is 13. Before starting the test, oxygen is pre-purged into the electrolyte solution for 30 min. The wavelength of the light source can be divided into three intervals of 380-800 nm, 440-800 nm and 540-800 nm through a filter and a monochromator. During photoelectrochemical testing, the set potential is (-0.5)-(+0.5) V (relative to the Ag / AgCl reference electrode), with a step size of 0.1 V; at each potential, the light response of the photoanode in the three wavelength intervals of 380-800 nm, 440-800 nm and 540-800 nm is tested, and the acquisition time of the photocurrent signal is 5 s, and each wavelength interval is tested four times.

[0065] Photoelectric conversion efficiency (IPCE) test condition: the electrolyte solution used is 0.1 mol / L KOH solution, and the solution pH value is 13. Before starting the test, oxygen is pre-purged into the electrolyte solution for 30 min. The light source is set to monochromatic light through a filter and a monochromator, and the light intensity at each wavelength is pre-tested by a light intensity tester. During photoelectrochemical testing, the set potential is -0.4 V (relative to the Ag / AgCl reference electrode); the acquisition time of the photocurrent signal is 5 s, and each wavelength is tested four times, and the IPCE value at each wavelength is calculated after the test is completed.

[0066] Figure 3 The present application is a scanning electron microscope (SEM) photograph provided by Comparative Example 1, Comparative Example 2, Comparative Example 4, and an energy spectrum analysis diagram of Comparative Example 4, wherein LaFeO3 is represented by the abbreviation "LFO". In the figure, a and b are the cross-sectional view and energy spectrum analysis diagram of Comparative Example 4 (LFO thin film). In the figure, c is the surface condition of Comparative Example 1 (LFO / TiO2), and the LFO surface prepared on TiO2 is smooth. In the figure, d is the surface condition of Comparative Example 2 (Au / TiO2), and it can be seen that the Au nanoparticles have been uniformly loaded on TiO2, and the particle size is relatively uniform, with a particle size of 15-50 nm, which is conducive to the exertion of LSPR effect and the improvement of the photoelectric performance of the photoanode. On the basis of Comparative Example 2, Example 1 and Example 2 are further prepared, and indeed have more excellent photoelectrocatalytic performance in subsequent tests.

[0067] Figure 4is the ultraviolet absorption spectrum data chart provided by the embodiment one, the embodiment two and the comparative example one and the comparative example three of the present application, wherein LaFeO3 is referred to as "LFO". The comparative example one (LFO / TiO2) increases the LFO absorption layer on the basis of the comparative example three (TiO2), and generates stronger light absorption in the region near 400 nm. The embodiment one (LFO / Au / TiO2) and the embodiment two (LFO / TiO2 / Au / TiO2) increase the Au nanoparticles with LSPR effect in two ways on the basis of the comparative example one, and both result in the generation of LSPR absorption peak near 600 nm. Among them, the embodiment two generates a higher LSPR absorption peak, because the Au nanoparticles in the TiO2 interlayer are not in direct contact with LFO, the leakage current is smaller, resulting in stronger light absorption near 600 nm.

[0068] Figure 5 is the on-off data chart provided by the embodiment two, the embodiment one and the comparative example one of the present application from left to right, in the solution with pH value of 13, the light response of the three photoanodes in the wavelength interval of 380-800 nm, 440-800 nm and 540-800 nm at each potential of (-0.5)-(+0.5) V (relative to Ag / AgCl reference electrode) is tested. Among them, the photocurrent density generated by the embodiment one and the embodiment two is obviously higher than that of the comparative example one, because the modification of the Au nanoparticles with LSPR effect makes the photoanode improve the light absorption efficiency, thereby generating significantly enhanced light response.

[0069] Figure 6 is the IPCE data chart provided by the embodiment two, the embodiment one and the comparative example one of the present application from top to bottom, in the solution with pH value of 13, the test is carried out at the potential of -0.4 V (relative to Ag / AgCl reference electrode). Among them, the IPCE curves of the embodiment one and the embodiment two generate LSPR absorption peak near 600 nm compared with the comparative example one, because the modification of the Au nanoparticles makes the photoanode improve the light absorption range. The peak value of the IPCE curve of the embodiment two at 600 nm is even about 5 times of that of the embodiment one, which shows that the Au nanoparticles in the TiO2 interlayer without direct contact with LFO have better enhancement effect on the photoanode.

[0070] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited thereto, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement methods, and shall be covered within the protection scope of the present application.

Claims

1. An Au-modified LaFeO3-based semiconductor thin-film photoelectrochemical water splitting photoanode, characterized in that, The Au-modified LaFeO3-based photoanode comprises a transparent conductive substrate, a wide bandgap semiconductor layer on the conductive substrate, an Au nanoparticle layer on the wide bandgap semiconductor layer, and a LaFeO3 absorption layer on the Au nanoparticle layer. The photoanode structure is LaFeO3 / Au / TiO2 / FTO. The improved Au-modified LaFeO3-based photoanode with better performance has the structure LaFeO3 / TiO2 / Au / TiO2 / FTO.

2. The Au-modified LaFeO3-based semiconductor thin film photoelectrochemical water splitting photoanode according to claim 1, characterized in that, The transparent conductive substrate is an FTO glass sheet.

3. The Au-modified LaFeO3-based semiconductor thin film photoelectrochemical water splitting photoanode according to claim 1, characterized in that, The wide bandgap semiconductor layer is a TiO2 layer.

4. The Au-modified LaFeO3-based semiconductor thin film photoelectrochemical water splitting photoanode according to claim 3, characterized in that, The thickness of the wide bandgap semiconductor layer is 400–600 nm.

5. The Au-modified LaFeO3-based semiconductor thin film photoelectrochemical water splitting photoanode according to claim 1, characterized in that, The thickness of the Au nanoparticle layer is 6 nm.

6. The Au-modified LaFeO3-based semiconductor thin film photoelectrochemical water splitting photoanode according to claim 5, characterized in that, The Au nanoparticles have a particle size of 15–50 nm.

7. The Au-modified LaFeO3-based semiconductor thin film photoelectrochemical water splitting photoanode according to claim 1, characterized in that, The LaFeO3 absorber layer is a double layer.

8. The Au-modified LaFeO3-based semiconductor thin film photoelectrochemical water splitting photoanode according to claim 7, characterized in that, The overall thickness of the LaFeO3 absorber layer is 400–600 nm.

9. The Au-modified LaFeO3-based semiconductor thin film photoelectrochemical water splitting photoanode according to any one of claims 1 to 8, characterized in that, The photoanode is the working electrode in the three-electrode system, which also includes an Ag / AgCl reference electrode, a Pt counter electrode, and an electrochemical workstation. The electrochemical workstation provides a voltage source, and the working electrode, reference electrode, and counter electrode are connected to the electrochemical workstation.

10. A method for preparing an Au-modified LaFeO3-based semiconductor thin film photoelectrochemical water splitting photoanode according to any one of claims 1 to 9, characterized in that, Includes the following steps: Step 1: TiO2 thin films are grown on FTO using liquid phase deposition and annealing techniques; Step 2: A layer of Au nanoparticles is prepared using vacuum evaporation and annealing techniques. Step 3: LaFeO3 thin film layer is prepared by sol-gel spin coating and annealing.

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