Bismuth sulfide / bismuth tungstate / tungsten trioxide photoanode, preparation method thereof and application of photoelectrocatalytic hydrogen evolution

Abstract

The invention provides a bismuth sulfide / bismuth tungstate / tungsten trioxide photo-anode and a preparation method and application of the photo-anode in photoelectrocatalytic hydrogen evolution, a WO3 nanosheet is grown on an FTO substrate through a chemical bath deposition method, then Bi2WO6 is loaded on the surface of WO3 through a solvothermal method to prepare Bi2WO6 / WO3, and then a Bi2S3 / Bi2WO6 / WO3 composite film is prepared through an anion exchange method. The photoanode shows efficient photoelectrocatalytic hydrolysis hydrogen production performance in an alkaline electrolyte, the photoelectrocatalytic hydrolysis hydrogen production amount under bias voltage auxiliary simulation sunlight irradiation reaches 330 [mu] mol / h or above, and the photoelectrocatalytic hydrolysis hydrogen production amount under solar cell auxiliary outdoor sunlight irradiation reaches 260 [mu] mol / h or above. According to the preparation method, a Bi2WO6 / WO3 heterostructure is formed through in-situ growth, Bi2WO6 / WO3 is vulcanized through a simple anion exchange method, the synergistic effect of bismuth sulfide / bismuth tungstate / tungsten trioxide ternary heterojunction exerts excellent photoelectrocatalysis hydrogen production performance, and good stability is kept in a 24h photocurrent response test.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoelectrocatalytic hydrogen evolution, and specifically relates to a method for preparing a bismuth sulfide / bismuth tungstate / tungsten trioxide photoanode as a photoelectrocatalyst and the application of photoelectrocatalytic hydrogen evolution. Background Art

[0002] Hydrogen energy has attracted wide attention as an efficient and pollution-free energy carrier. Photoelectrocatalytic water decomposition technology can convert solar energy into chemical energy, which can reduce environmental pollution while obtaining clean energy hydrogen, and has important environmental significance. Compared with traditional photocatalysts, photoelectrocatalysts show more outstanding catalytic performance, which not only significantly improves the energy conversion efficiency, but also better meets the needs of modern industry for efficient, economical and environmentally friendly catalysts, which helps to reduce production costs and promote the sustainable development of related industries. Photoelectrocatalytic technology can adjust the energy band structure of the catalyst by applying an external voltage, making it more suitable for the separation and transmission of photogenerated electrons and holes, and further improve the reaction activity. Compared with electrocatalysis, photoelectrocatalytic reactions greatly reduce the injection of external energy. In the photoelectrocatalytic process, sunlight, as the main source of energy, is not only abundant and sustainable, but also effectively reduces energy consumption. Photoelectrocatalytic technology can make more full use of sunlight, including visible light and part of infrared light, which account for a large proportion of the solar spectrum. Through strategies such as photoelectrothermal synergistic catalysis, the utilization efficiency of infrared light can be further improved, thereby improving the overall energy efficiency.

[0003] Selecting the right semiconductor material is the key to improving the efficiency of photoelectrocatalytic hydrogen evolution. Common semiconductor materials include metal oxides, sulfides, nitrides, etc. Bismuth-based semiconductor materials such as bismuth sulfide and bismuth tungstate have potential application value in the field of photoelectrocatalytic hydrogen evolution because of their suitable band gap, good visible light response performance and high photocatalytic activity. Metal oxide WO 3 It is a typical n-type indirect bandgap semiconductor with a suitable bandgap (about 2.7 eV). 3Many contributions have been made in PEC water splitting and pollutant degradation. With a unique crystal structure, this structure gives it good light absorption characteristics and channels that are conducive to charge transfer. It shows broad application prospects in the fields of photocatalysis and photoelectrocatalysis. For example, it has been deeply studied in the photocatalytic degradation of organic pollutants, photoelectrocatalytic water splitting to produce hydrogen, and solar cells. By forming a heterojunction with other semiconductor materials and utilizing the energy band matching between different semiconductors, it can promote the separation and migration of photogenerated carriers and significantly improve the efficiency of photocatalysis and photoelectrocatalysis. Among the many heterojunction systems based on, the heterojunction composed of narrow bandgap semiconductor materials shows excellent performance in photoelectrocatalytic water splitting to produce hydrogen. Bismuth sulfide has good conductivity and light absorption properties, and bismuth tungstate and tungsten trioxide have high stability and catalytic activity. Therefore, bismuth sulfide / bismuth tungstate / tungsten trioxide composite film as a stable and efficient photocatalyst for photoelectrocatalytic water splitting to produce hydrogen has become a promising environmental protection technology.

[0004] Photoelectric system is an ideal strategy that combines the advantages of photocatalysis and electrocatalysis to extend the life of electrons and achieve efficient energy conversion. In this system, photocatalysis can use light energy to excite catalysts to produce electron-hole pairs, while electrocatalysis can regulate the transfer and reaction process of electrons by applying an external electric field. The synergistic effect of the two enables electrons to participate in chemical reactions more effectively, thereby improving energy conversion efficiency. For example, Wang et al. successfully prepared highly efficient gC by a simple two-step solid-state annealing method. 3 N 4 / WO 3 Z-type heterojunction photocatalysts and studied their photoelectrocatalytic hydrogen production performance. Liu et al. studied the photogenerated charge transfer-promoted Bi 2 WO 6 / TiO 2 The photoelectrocatalytic hydrogen production performance of the composite photocatalyst was studied. It was found that the composite photocatalyst can effectively improve the separation efficiency of photogenerated carriers, thereby enhancing the photoelectrocatalytic hydrogen production activity, providing an effective method to solve the problem of photogenerated charge recombination in the photocatalytic process. These studies have provided valuable references and lessons for the development of photoelectrocatalytic water decomposition hydrogen production technology. According to the above viewpoints, an ideal photoelectric-assisted system photocatalyst should have at least the following characteristics: (1) excellent light absorption to achieve complete carrier excitation and high level of energy injection; (2) fast carrier separation and migration dynamics to promote the formation of the initial state.

[0005] In addition to high catalytic activity, the separation of photoelectrocatalysts from the reaction system is crucial for the practical application and commercialization of photoelectrocatalytic technology. Summary of the invention

[0006] In view of this, the present invention aims to propose a bismuth sulfide / bismuth tungstate / tungsten trioxide photoanode and its preparation method and application in photoelectrocatalytic hydrogen evolution, to construct a ternary heterojunction to increase WO 3 The light absorption capacity of the nanosheets and the synergistic effect of the ternary heterojunction promote the migration of photogenerated electrons and provide more surface active sites to promote the water decomposition reaction.

[0007] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0008] A method for preparing a bismuth sulfide / bismuth tungstate / tungsten trioxide composite film, the method comprising the following steps: firstly growing WO on a FTO substrate by a chemical bath deposition method; 3 Nanosheets, then Bi 2 WO 6 Solvothermal method was used to load the 3 Bi 2 WO 6 / WO 3 , and then Bi was obtained by anion exchange method 2 S 3 / Bi 2 WO 6 / WO 3 Composite film;

[0009] The method comprises the following steps:

[0010] (1) Preparation of WO 3 :

[0011] Sodium tungstate dihydrate is used as tungsten source, deionized water and hydrochloric acid are used as solvents to prepare a solution. After the solution is fully stirred, ammonium oxalate is added to obtain a precursor solution for standby use. The treated fluorine-doped tin oxide glass substrate is placed in a beaker with the conductive surface facing down, and then the prepared solution is slowly poured in. The sealed beaker is placed in a water bath at 80°C for 12 hours, and then the grown film sample is taken out from the suspension, washed with deionized water and dried, placed in a muffle furnace, heated to 500°C at a heating rate of 2°C / min, calcined for 2 hours, and naturally cooled to room temperature to obtain WO 3 Nanosheet films;

[0012] (2) Preparation of Bi 2 WO 6 / WO 3 :

[0013] Use bismuth nitrate pentahydrate as bismuth source, sodium tungstate dihydrate as tungsten source, ethylene glycol as solvent, stir well at room temperature, put the stirred precursor solution into the inner tank of 50mL reactor, and add WO 3The film was placed face down in the reactor liner. The reactor was heated to 160°C in a drying oven and kept warm for 15 hours. After cooling to room temperature, the sample was taken out and the film was rinsed with deionized water and then dried at 80°C for 12 hours. Finally, the deposited film sample was placed in a muffle furnace and heated to 450°C for annealing for 2 hours to obtain Bi 2 WO 6 / WO 3 Composite film;

[0014] (3) Preparation of Bi 2 S 3 / Bi 2 WO 6 / WO 3 :

[0015] Sodium sulfide nonahydrate was used as the sulfur source and deionized water was used as the solvent to prepare the precursor solution. 2 WO 6 / WO 3 The composite film was immersed in the precursor solution for 1 h, then rinsed with deionized water, and then placed in a vacuum drying oven at 60 °C for 6 h to obtain Bi 2 S 3 / Bi 2 WO 6 / WO 3 Composite film.

[0016] Furthermore, in the step (1), the amount of sodium tungstate dihydrate used is 0.197 g, the solvent is 30 mL of ultrapure water and 5.2 mL of hydrochloric acid aqueous solution, 0.19 g of ammonium oxalate is added after sufficient stirring, and the mixture is kept at 80° C. for 12 h. The annealing process is to keep the mixture at 500° C. in air for 120 min.

[0017] Furthermore, in the step (2), the amount of bismuth nitrate pentahydrate is 0.849 g, the amount of sodium tungstate dihydrate is 0.289 g, and the amount of ethylene glycol is 35 mL.

[0018] Further, in step (3), Bi 2 S 3 The growth precursor solution was 0.1 M Na 2 S solution.

[0019] The present invention adopts a two-step in-situ conversion method, which is simple, low-cost, and Bi 2 S 3 / Bi 2 WO 6 / WO 3 It is evenly distributed on FTO, and as a photoelectrolysis water catalyst, it has a good photoelectrolysis water hydrogen production capacity. The whole reaction operation is simple, and large-scale industrial production can be achieved. The sample separation is convenient for repeated use.

[0020] The present invention also provides a bismuth sulfide / bismuth tungstate / tungsten trioxide thin film composite material obtained according to the above-mentioned preparation method.

[0021] The present invention also provides an application of the bismuth sulfide / bismuth tungstate / tungsten trioxide thin film composite material obtained according to the above-mentioned preparation method in photoelectrocatalytic water decomposition to produce hydrogen.

[0022] Compared with the prior art, the bismuth sulfide / bismuth tungstate / tungsten trioxide thin film composite material and its preparation method and application described in the present invention have the following advantages:

[0023] The bismuth sulfide / bismuth tungstate / tungsten trioxide film composite material of the present invention exhibits efficient photoelectrocatalytic hydrolysis hydrogen production performance in alkaline electrolyte. The hydrogen production of photoelectrocatalytic hydrolysis under bias-assisted simulated sunlight irradiation reaches more than 330 μmol / h, and the hydrogen production of photoelectrocatalytic hydrolysis under solar cell-assisted outdoor sunlight irradiation reaches more than 260 μmol / h. The synergistic effect of the ternary heterojunction exerts excellent photoelectrocatalytic hydrogen production performance, and maintains good stability in the 24h photocurrent response test, and the sample separation is convenient for reuse. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the features, technical means and specific purposes and functions achieved by the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0025] Figure 1 for Bi 2 S 3 / Bi 2 WO 6 / WO 3 SEM images of the composite films;

[0026] Figure 2 for Bi 2 S 3 / Bi 2 WO 6 / WO 3 SEM-EDS elemental mapping of the composite film;

[0027] Figure 3 For WO 3 、Bi 2 WO 6 / WO 3 and Bi 2 S 3 / Bi 2 WO 6 / WO 3 XRD patterns of thin films;

[0028] Figure 4 For WO3 and Bi 2 S 3 / Bi 2 WO 6 / WO 3 (a) Linear sweep voltammetric curves (JV) of the photoanode under simulated solar light irradiation and dark state (b) 0.87V RHE Transient chopping photocurrent response under (c) monochromatic light-to-electric conversion efficiency (IPCE) (d) Bi 2 S 3 / Bi 2 WO 6 / WO 3 Long-term stability test of photoanode;

[0029] Figure 5 For WO 3 and Bi 2 S 3 / Bi 2 WO 6 / WO 3 Photoelectrocatalytic hydrogen production performance of the photoanode under different test conditions; DETAILED DESCRIPTION

[0030] Experimental materials: sodium tungstate dihydrate (China Aladdin Reagent Company), sodium sulfide nonahydrate (China Aladdin Reagent Company), bismuth nitrate pentahydrate (Shanghai McLean Biochemical Technology Co., Ltd.), ammonium oxalate (Shanghai McLean Biochemical Technology Co., Ltd.) purchased from Shanghai McLean Biochemical Technology Co., Ltd., hydrochloric acid (Tianjin Fengchuan Chemical Reagent Technology Co., Ltd.), ethylene glycol (Shanghai Titan Technology Co., Ltd.).

[0031] Experimental instruments: water bath, oven, electronic balance, other glass instruments, etc.

[0032] Solvothermal preparation of WO attached to a rigid substrate of fluorine-doped tin oxide glass 3 Nanosheets; The specific operation steps are: use sodium tungstate dihydrate as the tungsten source, deionized water and hydrochloric acid as solvents to prepare a solution, stir the solution thoroughly, and then add ammonium oxalate to obtain a precursor solution for standby use. Place the treated fluorine-doped tin oxide glass substrate in a beaker with the conductive surface facing down. Then slowly pour the prepared solution in, and place the sealed beaker in an 80°C water bath for 12 hours. Then take the grown thin film sample out of the suspension, wash it with deionized water and dry it, put it in a muffle furnace, heat it to 500°C at a heating rate of 2°C / min, calcine it for 2 hours, and naturally cool it to room temperature to obtain WO 3 Nanosheet film for further experiments.

[0033] Use bismuth nitrate pentahydrate as bismuth source, sodium tungstate dihydrate as tungsten source, and ethylene glycol as solvent, and stir them thoroughly at room temperature. Put the stirred precursor solution into the inner tank of a 50mL reactor and add WO 3 The film was placed face down in the reactor liner, and the reactor was heated to 160°C in a drying oven and kept warm for 15 hours. After cooling to room temperature, the sample was taken out, the film was rinsed with deionized water, and then dried at 80°C for 12 hours. Finally, the deposited film sample was placed in a muffle furnace, heated to 450°C and annealed for 2 hours to obtain Bi 2 WO 6 / WO 3 Composite film for further experiments

[0034] The precursor solution was prepared using sodium sulfide nonahydrate as the sulfur source and deionized water as the solvent. 2 WO 6 / WO 3 The composite film was immersed in the precursor solution for 1 h, then rinsed with deionized water, and then placed in a vacuum drying oven at 60 °C for 6 h to obtain Bi 2 S 3 / Bi 2 WO 6 / WO 3 Composite film.

[0035] The prepared Bi 2 S 3 / Bi 2 WO 6 / WO 3 The composite film was placed in a quartz reactor as a photoanode, a platinum sheet as a photocathode, and silver / silver chloride as a reference electrode. 15 mL of sodium sulfide and sodium sulfite aqueous solution was added. The Swiss Metrohm MultiAutolab / M204 multi-channel electrochemical workstation was used for power supply and photoelectrochemical testing. The reactor was transferred to the gas path to pass argon for 30 minutes to exhaust the air in the reactor. A 300 W xenon lamp (Zolix Sirius 300P) was used as a simulated sunlight light source, and a gas chromatograph (Shimadzu, GC2014C) was used to detect H 2 The concentration was measured using a TCD detector and high-purity Ar as the carrier gas.

[0036] A 300W xenon lamp (Zolix Sirius 300P) was used as a simulated sunlight source to illuminate the solar panels (4×4cm 2 , 2) and photoanode, and carried out solar cell photoelectrochemical water splitting hydrogen production test. The solar cell photoelectrochemical water splitting test was carried out under outdoor sunlight with the same system.

[0037] like Figure 1 Bi 2 S 3 / Bi 2 WO 6 / WO 3 Microstructure of the film, WO 3 The nanosheet arrays are uniformly and vertically grown on FTO, loaded with Bi 2 WO 6 Later, Bi 2 WO 6 The nanosheets were uniformly deposited and completely covered the WO 3 Nanosheets, using anion exchange method, Bi 2 WO 6 In-situ conversion to Bi 2 S 3 / Bi 2 WO 6 Composite structure, the surface morphology of the film tends to expand and loosen.

[0038] like Figure 2 Bi 2 S 3 / Bi 2 WO 6 / WO 3 SEM-EDS elemental mapping of the film, showing that the first layer is Bi 2 S 3 / Bi 2 WO 6 / WO 3 Thin film layer, the second layer is FTO F / SnO 2 The conductive layer and the third layer are FTO glass layers. 2 S 3 / Bi 2 WO 6 / WO 3 The thin film layer shows uniform distribution of Si, Sn, O, W, Bi and S. The overlap of Bi and W indicates that Bi 2 WO 6 Nanosheets grow uniformly throughout the WO 3 The positions of O and S elements and Bi elements also overlap, indicating that the anion exchange process makes all Bi 2 WO 6 The conversion of the nanosheets into Bi 2 S 3 .

[0039] like Figure 3 It is WO 3 、Bi 2 WO 6 / WO 3 and Bi 2 S 3 / Bi2 WO 6 / WO 3 XRD patterns of the films. The 2θ diffraction peaks of 22.9°, 23.5°, 24.2°, and 33.9° in all samples come from the monoclinic phase WO 3 Diffraction of (002), (020), (200) and (202) planes of (JCPDS No. 43-1035). 2 WO 6 / WO 3 and Bi 2 S 3 / Bi 2 WO 6 / WO 3 Four small diffraction peaks were observed at 28.3°, 32.7°, 47.1° and 55.8°, which are Bi 2 WO 6 (JCPDS No.39-0256) has characteristic diffraction peaks on the (131), (002), (202) and (280) planes. 2 S 3 / Bi 2 WO 6 / WO 3 The weak diffraction peak at 28.9° observed in the sample is the orthorhombic Bi 2 S 3 The characteristic diffraction peak of the (211) crystal plane of WO (JCPDS No.17-0320). The results show that the solvothermal growth process was successful on WO 3 A layer of Bi grows on the surface 2 WO 6 , and then after the ion exchange process, Bi 2 WO 6 Partial conversion to Bi 2 S 3 .

[0040] Figure 4 a is WO 3 and Bi 2 S 3 / Bi 2 WO 6 / WO 3 IV curves of the photoanode under simulated solar light irradiation and in the dark state. 3 The photocurrent response is the lowest, which is mainly due to the 3 The light absorption of Bi is insufficient, and the carrier separation and migration performance is poor. 2 S 3 / Bi 2 WO 6The photocurrent density is significantly improved due to the introduction of narrow bandgap semiconductor Bi 2 S 3 , the light absorption range of the sample is enhanced, thereby improving the photoelectric response characteristics. This shows that the heterostructure is conducive to the separation and transfer of carriers and is conducive to obtaining high-performance solar hydrogen energy conversion efficiency. Figure 4 b is WO 3 and Bi 2 S 3 / Bi 2 WO 6 / WO 3 The photoanode is at 0.87V RHE Jt curve under bias, during repeated on / off illumination test, all photoanodes reach peak value immediately after light is turned on, and reach steady-state photocurrent density after about 1s, and remain stable during the light-on period. This indicates that the photoanode has good instantaneous photoresponse characteristics and photocurrent stability. 0.87V RHE When biased, WO 3 and Bi 2 S 3 / Bi 2 WO 6 / WO 3 The steady-state photocurrent density of the photoanode is 0.9 and 6.6 mA respectively. The photocurrent density variation trend of the Jt curve is consistent with the IV result. 2 S 3 / Bi 2 WO 6 / WO 3 Sample at 0.87V RHE The photocurrent density under bias is WO 3 91 times that of photoanode. WO 3 and Bi 2 S 3 / Bi 2 WO 6 / WO 3 The IPCE curve of the photoanode under continuous light at a wavelength of 300-800nm ​​is as follows: Figure 4 c. Bi 2 S 3 / Bi 2 WO 6 / WO 3 The IPCE value is high in the continuous wavelength range of 300-800nm. When irradiated with 420nm light, WO 3 and Bi 2 S 3 / Bi 2 WO 6 / WO 3The IPCE of the photoanode was 0.3% and 2.91% respectively. After 420nm, the IPCE efficiency stabilized until 800nm, and the IPCE value remained above 2.5%. This further confirmed that by 3 Upper load Bi 2 S 3 and Bi 2 WO 6 The photoelectric conversion efficiency of the entire spectrum from ultraviolet to visible light in PEC water splitting can be significantly improved. Figure 4 d shows Bi 2 S 3 / Bi 2 WO 6 / WO 3 Jt curve of the photoanode at 0.47V bias and continuous illumination for 72000s, Bi 2 S 3 / Bi 2 WO 6 / WO 3 The photocurrent density of the photoanode gradually increased within the initial 30 minutes, which was due to the electrolyte's 2 WO 6 As a result of further sulfurization, the photocurrent density of the photoanode remained constant within 72,000 s without a significant decrease, indicating that the film can be used for long-term continuous PEC testing. 2 S 3 / Bi 2 WO 6 / WO 3 In the photoanode, Bi 2 WO 6 The intermediate layer promotes the separation and directional transfer of photogenerated carriers and inhibits the oxidation of WO 3 Photogenerated holes 2 S 3 direct transfer, thus showing excellent photoelectric conversion characteristics and stability.

[0041] like Figure 5 As shown, in order to verify the practical application of the prepared photoanode, PEC hydrogen production tests were carried out under different test conditions. First, under simulated sunlight and 0.87V RHE Under a fixed bias voltage, the photoelectrocatalytic hydrogen production performance of all samples was studied. 2 S 3 / Bi 2 WO 6 / WO 3 Shows much higher than WO 3 The product 2The photoelectrocatalytic hydrogen production in 1h reaches 82.5μmol / h, far exceeding WO 3 In addition, WO 3 and Bi 2 S 3 / Bi 2 WO 6 / WO 3 The test results of the photoanode under simulated sunlight + solar cell and outdoor sunlight + solar cell are similar to the above results. The hydrogen production within one hour follows the Bi 2 S 3 / Bi 2 WO 6 / WO 3 >WO 3 It is proved that the prepared photoanode has good repeatability and can maintain a stable photocurrent when powered by a solar panel.

[0042] Finally, it should be noted that the above embodiments are only used for the technical solutions of the present invention, rather than limiting the present invention. Although the present invention is described in detail with reference to the above examples, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the above embodiments, or make equivalent replacements for the technical features therein, and these modifications or replacements do not make the essence of the desired technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a bismuth sulfide / bismuth tungstate / tungsten trioxide composite film, characterized in that: The following steps are involved: Firstly, WO3 nanosheets were grown on FTO substrate by chemical bath deposition, and then Bi2WO6 was loaded on the surface of WO3 by solvothermal method to prepare Bi2WO6 / WO3, and then Bi2S3 / Bi2WO6 / WO3 composite film was prepared by anion exchange method. The method comprises the following steps: (1) WO3 nanosheets attached to a fluorine-doped tin oxide glass rigid substrate were prepared by chemical bath deposition; the specific operation steps are as follows: Sodium tungstate dihydrate was used as the tungsten source, and deionized water and hydrochloric acid were used as solvents to prepare a solution. After the solution was fully stirred, ammonium oxalate was added to obtain a precursor solution for standby use. The treated fluorine-doped tin oxide glass substrate was placed in a beaker with the conductive surface facing downward, and the prepared solution was slowly poured in. The sealed beaker was placed in a water bath at 80°C for 12 hours, and then the grown film sample was taken out from the suspension, washed with deionized water and dried, placed in a muffle furnace, heated to 500°C at a heating rate of 2°C / min, calcined for 2 hours, and naturally cooled to room temperature to obtain a WO3 nanosheet film. (2) Use bismuth nitrate pentahydrate as bismuth source, sodium tungstate dihydrate as tungsten source, ethylene glycol as solvent, stir well at room temperature, put the stirred precursor solution into a 50mL reactor liner, and put the WO3 film face down into the reactor liner. Heat the reactor to 160°C in a drying oven and keep it warm for 15h. After cooling to room temperature, take out the sample, rinse the film with deionized water, and then dry it at 80°C for 12h. Finally, put the deposited film sample into a muffle furnace, heat it to 450°C and anneal it for 2h to obtain a Bi2WO6 / WO3 composite film. (3) A precursor solution was prepared using sodium sulfide nonahydrate as the sulfur source and deionized water as the solvent. The Bi2WO6 / WO3 composite film was immersed in the precursor solution for 1 h, then rinsed with deionized water, and then placed in a vacuum drying oven at 60°C for 6 h to obtain a Bi2S3 / Bi2WO6 / WO3 composite film.

2. The method for preparing the bismuth sulfide / bismuth tungstate / tungsten trioxide composite film according to claim 1, characterized in that: Step (1) obtains a WO3 nanosheet film by chemical bath deposition. The specific operation steps are as follows: 0.197 g of sodium tungstate dihydrate is used as a tungsten source, 30 mL of deionized water and 5.2 mL of hydrochloric acid aqueous solution are used as solvents, 0.19 g of ammonium oxalate is added after sufficient stirring, and the mixture is kept at 80°C for 12 hours to directly obtain a WO3 nanosheet film.

3. The method for preparing a bismuth sulfide / bismuth tungstate / tungsten trioxide composite film as a hydrogen evolution photoelectrocatalyst according to claim 1, characterized in that: Step (2) 0.849 g of bismuth nitrate pentahydrate is used as a bismuth source, 0.289 g of sodium tungstate dihydrate is used as a tungsten source, and 35 mL of ethylene glycol is used as a solvent, and the mixture is stirred at room temperature to obtain a precursor solution for preparing Bi2WO6 / WO3. The mixture is heated to 160°C in a drying oven and then kept warm for 15 hours to in-situ grow Bi2WO6 on WO3 nanosheets to directly obtain a Bi2WO6 / WO3 composite film.

4. The method for preparing a bismuth sulfide / bismuth tungstate / tungsten trioxide composite film as a hydrogen evolution photoelectrocatalyst according to claim 1, characterized in that: Step (3) obtains a Bi2S3 / Bi2WO6 / WO3 composite film by an anion exchange method. The specific operation steps are: immerse the Bi2WO6 / WO3 film in a 0.1M Na2S solution for 1 hour, then rinse with deionized water, and then place it in a vacuum drying oven at 60°C for 6 hours to convert Bi2WO6 into Bi2S3 in situ, and directly obtain a Bi2S3 / Bi2WO6 / WO3 composite film.

5. A bismuth sulfide / bismuth tungstate / tungsten trioxide composite film prepared according to the preparation method according to any one of claims 1 to 4.

6. Application of bismuth sulfide / bismuth tungstate / tungsten trioxide composite film prepared by the preparation method according to any one of claims 1 to 4 in photoelectrocatalytic hydrogen evolution.

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