Copper-based chalcogenide solar water photolysis hydrogen production film photocathode and preparation method thereof

Abstract

The invention belongs to the technical field of photoelectrochemical water splitting photocathode material preparation, and particularly discloses a copper-based chalcogenide solar water photosplitting hydrogen production film photocathode and a preparation method thereof, the copper-based chalcogenide solar water photosplitting hydrogen production film photocathode comprises a Mo plated glass substrate, a copper-based chalcogenide film, a zinc tin oxide film, a TiO2 layer, a Pt layer and an Ag colloid electrode layer, and a gap is arranged between the Ag colloid electrode layer and the copper-based chalcogenide film. Compared with the prior art, the cadmium-free zinc tin oxide thin film is used as the electron transport layer, so that the cost is low, and the solar cell is environment-friendly and non-toxic; the thickness of the zinc tin oxide thin film is accurately regulated and controlled, so that the constructed copper-based chalcogenide / ZTO heterojunction energy band arrangement can present an ideal spike-like configuration, and the corresponding conduction band offset (namely the difference value between the conduction band bottom energy of the ZTO and the conduction band bottom energy of the copper-based chalcogenide) is 0-0.4 eV; accumulation and recombination of photon-generated carriers on an interface can be restrained in a limited mode, and efficient carrier transportation can be guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectrochemical water decomposition photocathode material preparation, in particular to a copper-based sulfur-based solar water photolysis hydrogen production thin film photocathode and a preparation method thereof. Background Art

[0002] In existing copper-based chalcogenide thin film photocathode technology, the N-type semiconductor (electron transport layer) mainly uses cadmium sulfide (CdS). Currently, it still has its advantages in terms of efficient carrier separation. However, CdS has three major drawbacks:

[0003] 1. CdS contains toxic cadmium, which poses safety and environmental risks during device preparation and use;

[0004] 2. The band gap of CdS is relatively low, at 2.4eV, which will absorb some high-energy photons (400-600nm) and cause parasitic current loss;

[0005] 3. During the CdS preparation process, the random diffusion of cadmium ions and sulfur ions into the light absorption layer under heat / light treatment may cause the device efficiency to decline. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a copper-based sulfur-based solar photocatalytic water splitting hydrogen production thin film photocathode and a preparation method thereof.

[0007] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0008] The first technical solution provided by the present invention is a copper-based sulfur-based solar photolysis water hydrogen production thin film photocathode, comprising a Mo-plated glass substrate, a copper-based sulfur-based thin film spin-coated on one side of the upper end surface of the Mo-plated glass substrate as a light absorption layer, a zinc-tin oxide thin film deposited on the upper end surface of the copper-based sulfur-based thin film as an electron transport layer, a TiO2 layer deposited on the upper end surface of the zinc-tin oxide thin film as a protective layer, a Pt layer deposited on the upper end surface of the TiO2 layer as a co-catalyst layer, and an Ag colloidal electrode layer as a conductive layer provided on the other side of the upper end surface of the Mo-plated glass substrate, with a gap between the Ag colloidal electrode layer and the copper-based sulfur-based thin film.

[0009] Furthermore, the copper-based chalcogenide thin film has a thickness of 500-1500 nm.

[0010] Furthermore, the zinc tin oxide film has a thickness of 5-25 nm.

[0011] Furthermore, the thickness of the TiO2 layer is 7-14 nm.

[0012] Furthermore, the thickness of the Pt layer is 5-10 nm.

[0013] Furthermore, the thickness of the Ag colloidal electrode layer is 0.1 mm.

[0014] The second technical solution provided by the present invention is a method for preparing a copper-based sulfur-based solar photocatalytic water splitting hydrogen production thin film photocathode, comprising the following steps:

[0015] S1. Dissolve SnCl4·5H2O, CuCl, Zn(CH3COO)2·2H2O, SC(NH2)2, SnCl2·2H2O, Cu(CH3COO)2·H2O, ZnCl2 and SC(NH2)2 in 2-ME solvent respectively, mix at 60°C for 90 minutes, and then dilute to half of its original concentration to prepare a copper-based chalcogenide thin film precursor solution, spin-coat the copper-based chalcogenide thin film precursor solution on one side of a Mo-coated glass substrate, and perform annealing at 300°C in air after each round of spin coating, and spin-coat 8-12 layers in total; then heat-treat at 550°C in a selenium, tin and argon atmosphere to form a copper-based chalcogenide thin film as a light absorption layer;

[0016] S2, depositing a zinc tin oxide film with a thickness of 5-25 nm as an electron transport layer on the copper-based chalcogenide film by atomic layer deposition;

[0017] S3, depositing a TiO2 layer as a protective layer on the zinc tin oxide film by atomic layer deposition;

[0018] S4, using an automatic sputtering machine to deposit a Pt layer as a promoter layer on the TiO2 layer at a current of 20 mA;

[0019] S5. A Ag colloidal electrode layer is coated on the other side of the Mo-coated glass substrate as a conductive layer, with a gap between the Ag colloidal electrode layer and the copper-based sulfide thin film; and a copper-based sulfide solar photocatalytic water splitting hydrogen production thin film photocathode is obtained.

[0020] Furthermore, the step S2 specifically includes:

[0021] Diethylzinc DEZ, tetrakis(dimethylamino)tin TDMASn and deionized water were used as zinc, tin and oxygen precursors, respectively. The temperatures of the diethylzinc DEZ precursor and the H2O precursor were kept at room temperature, while the temperatures of the stainless steel container, the delivery pipe and the reaction chamber for storing the tetrakis(dimethylamino)tin TDMASn precursor were set to 50-80°C, 80-120°C and 100-150°C, respectively. The MASn precursor and the H2O precursor are introduced into the atomic layer deposition reaction chamber in the order of one cycle. The deposition procedure includes a 40-80ms DEZ or TDMASn pulse, a 100-160ms H2O pulse and a 5-10s N2 purge. Two layers of ZnO and one layer of SnO2 films are formed in each cycle, and a zinc tin oxide film with a thickness of 0.3nm is formed in each cycle. Atomic layer deposition is set for a total of 17-83 cycles, and finally a zinc tin oxide film with a thickness of 5-25nm is formed on the copper-based chalcogenide film.

[0022] Furthermore, the step S3 specifically includes:

[0023] TiCl4 is used as the titanium source and H2O is used as the oxygen source. The reaction chamber and supply pipeline of TiCl4 are set to 80℃ and 190℃ respectively. TiCl4 and H2O are introduced into the atomic layer deposition reaction chamber in the order of one cycle. The deposition procedure includes a TiCl4 pulse of 40-80ms, an H2O pulse of 100-160ms and an N2 purge of 5-10s. A TiO2 film with a thickness of 0.07nm is formed in each cycle. Atomic layer deposition is set for a total of 100-200 cycles, and finally a TiO2 layer with a thickness of 7-14nm is formed on the zinc tin oxide film.

[0024] Furthermore, the step S4 specifically includes: using an automatic sputtering machine to deposit a Pt promoter for 50 seconds at a current of 20 mA, and finally forming a Pt layer with a thickness of 5-10 nm on the TiO2 layer.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The electron transport layer of the traditional photocathode relies on cadmium sulfide. Cadmium is a heavy metal that is extremely harmful to the environment. However, the present invention uses a cadmium-free zinc tin oxide film as the electron transport layer, which is low-cost, environmentally friendly and non-toxic.

[0027] 2. By precisely controlling the thickness of the zinc-tin oxide film, the energy band arrangement of the constructed copper-based sulfide compound / ZTO heterojunction can be achieved to present an ideal "spike-like" configuration, with the corresponding conduction band offset (i.e., the difference between the conduction band bottom energy of ZTO and the conduction band bottom energy of the copper-based sulfide compound) between 0 and 0.4 eV. This can not only effectively suppress the accumulation and recombination of photogenerated carriers at the interface, but also ensure efficient carrier transport. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic structural diagram of the copper-based sulfur-based solar photolysis water hydrogen production thin film photocathode of the present invention.

[0029] Figure 2 Schematic diagram of the pulse program and process for atomic layer deposition of zinc tin oxide (ZTO).

[0030] Figure 3 Figure 2 is the current-voltage diagram of ETL-2 and the corresponding half-cell efficiency diagram.

[0031] Figure 4 The diagram shows the band gap test results of three electron transport layers with different thicknesses and the conduction band matching diagram of copper-based sulfur compounds. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] Example 1

[0034] S1. Dissolve SnCl4·5H2O, CuCl, Zn(CH3COO)2·2H2O, SC(NH2)2, SnCl2·2H2O, Cu(CH3COO)2·H2O, ZnCl2 and SC(NH2)2 in 2-ME solvent respectively and mix them at 60℃ for 90min to obtain a mixed solution. The concentration of SnCl4 in the mixed solution is 0.83M, the concentration of CuCl is 1.42M, the concentration of Zn(CH3COO)2 is 1.0M, the concentration of SC(NH2)2 is 6.4M, and the concentration of SnCl2 is 0.83M. The concentration of Cu(CH3COO)2 is 0.83M, the concentration of Cu(CH3COO)2 is 1.42M, the concentration of ZnCl2 is 1.0M, and the concentration of SC(NH2)2 is 6.4M; the mixed solution is then diluted to half of its original concentration to prepare a copper-based chalcogenide thin film precursor solution, and the copper-based chalcogenide thin film precursor solution is spin-coated on one side of a Mo-coated glass substrate. After each round of spin-coating, an annealing treatment is performed in air at 300°C, and a total of 10 layers are spin-coated; then, a heat treatment is performed at 550°C in a selenium, tin, and argon atmosphere to form a copper-based chalcogenide thin film 2 with a thickness of about 1000nm as a light absorption layer;

[0035] S2, such as Figure 2 As shown in FIG, diethylzinc DEZ, tetrakis(dimethylamino)tin TDMASn and deionized water are used as precursors of zinc, tin and oxygen, respectively. The temperatures of the diethylzinc DEZ precursor and the H2O precursor are kept at room temperature, while the temperatures of the stainless steel container, the delivery pipe and the reaction chamber for storing the tetrakis(dimethylamino)tin TDMASn precursor are set to 60°C, 100°C and 120°C, respectively. The diethylzinc DEZ precursor, the H2O precursor, the diethylzinc DEZ precursor, the H2O precursor, the tetrakis(dimethylamino)tin TDMASn precursor and the H2O precursor are introduced into the atomic layer deposition reaction chamber in the order of one cycle, and the deposition process is as follows: The sequence includes a 60ms DEZ or TDMASn pulse, a 100ms H2O pulse, and a 5-10s N2 purge. Two layers of ZnO and one layer of SnO2 thin films are formed in each cycle. A zinc-tin oxide film with a thickness of 0.3nm is formed in each cycle. Atomic layer deposition is performed for a total of 17 cycles, and finally a zinc-tin oxide film 3 with a thickness of 5nm is formed on the copper-based chalcogenide film 2. In this embodiment, the concentration of oxygen vacancies in the zinc-tin oxide films 3 of different thicknesses is controlled mainly by controlling the pulse intensity of the water source during the ZnO and SnO2 deposition process, thereby changing the band gap value and CBO value of the ETL of different thicknesses.

[0036] S3, using TiCl4 as a titanium source and H2O as an oxygen source, with the TiCl4 reaction chamber and supply pipeline set to 80°C and 190°C, respectively, and introducing TiCl4 and H2O into the atomic layer deposition reaction chamber in this order for one cycle. The deposition procedure includes a 60ms TiCl4 pulse, a 100ms H2O pulse, and a 5-10s N2 purge. Each cycle forms a TiO2 film with a thickness of 0.07nm. Atomic layer deposition is performed for a total of 100 cycles, ultimately forming a TiO2 layer 4 with a thickness of 7nm on the zinc-tin oxide film 3.

[0037] S4, using an automatic sputtering machine to deposit a Pt promoter at a current of 20 mA for 50 seconds, ultimately forming a Pt layer 5 with a thickness of 10 nm on the TiO2 layer 4;

[0038] S5. A 0.1 mm thick Ag colloidal electrode layer 6 is coated on the other side of the Mo-coated glass substrate 1 as a conductive layer, with a gap between the Ag colloidal electrode layer 6 and the copper-based chalcogenide film 2. The obtained copper-based chalcogenide solar photocatalytic water splitting hydrogen production film photocathode is denoted as ETL-1. For the specific structure, see Figure 1 .

[0039] Example 2

[0040] S1. Dissolve SnCl4·5H2O, CuCl, Zn(CH3COO)2·2H2O, SC(NH2)2, SnCl2·2H2O, Cu(CH3COO)2·H2O, ZnCl2 and SC(NH2)2 in 2-ME solvent respectively and mix them at 60℃ for 90min to obtain a mixed solution. The concentration of SnCl4 in the mixed solution is 0.83M, the concentration of CuCl is 1.42M, the concentration of Zn(CH3COO)2 is 1.0M, the concentration of SC(NH2)2 is 6.4M, and the concentration of SnCl2 is 0.83M. The concentration of Cu(CH3COO)2 is 0.83M, the concentration of Cu(CH3COO)2 is 1.42M, the concentration of ZnCl2 is 1.0M, and the concentration of SC(NH2)2 is 6.4M; the mixed solution is then diluted to half of its original concentration to prepare a copper-based chalcogenide thin film precursor solution, and the copper-based chalcogenide thin film precursor solution is spin-coated on one side of a Mo-coated glass substrate. After each round of spin-coating, an annealing treatment is performed in air at 300°C, and a total of 10 layers are spin-coated; then, a heat treatment is performed at 550°C in a selenium, tin, and argon atmosphere to form a copper-based chalcogenide thin film 2 with a thickness of about 1000nm as a light absorption layer;

[0041] S2, such as Figure 2As shown, diethylzinc DEZ, tetrakis(dimethylamino)tin TDMASn and deionized water are used as zinc, tin and oxygen precursors, respectively. The temperatures of the diethylzinc DEZ precursor and the H2O precursor are kept at room temperature, while the temperatures of the stainless steel container, the delivery pipe and the reaction chamber for storing the tetrakis(dimethylamino)tin TDMASn precursor are set to 60°C, 100°C and 120°C, respectively. A DMASn precursor and an H2O precursor are introduced into the atomic layer deposition reaction chamber in the order of one cycle. The deposition process includes a 60ms DEZ or TDMASn pulse, a 100ms H2O pulse, and a 5-10s N2 purge. Two layers of ZnO and one layer of SnO2 thin films are formed in each cycle, respectively. A total of 0.3nm thick zinc-tin oxide films are formed in each cycle. Atomic layer deposition is performed for a total of 51 cycles, ultimately forming a 15nm thick zinc-tin oxide film 3 on the copper-based chalcogenide film 2.

[0042] S3, using TiCl4 as a titanium source and H2O as an oxygen source, with the TiCl4 reaction chamber and supply pipeline set to 80°C and 190°C, respectively, and introducing TiCl4 and H2O into the atomic layer deposition reaction chamber in this order for one cycle. The deposition procedure includes a 60ms TiCl4 pulse, a 130ms H2O pulse, and a 5-10s N2 purge. Each cycle forms a TiO2 film with a thickness of 0.07nm. Atomic layer deposition is performed for a total of 100 cycles, ultimately forming a TiO2 layer 4 with a thickness of 7nm on the zinc-tin oxide film 3;

[0043] S4, using an automatic sputtering machine to deposit a Pt promoter at a current of 20 mA for 50 seconds, ultimately forming a Pt layer 5 with a thickness of 10 nm on the TiO2 layer 4;

[0044] S5. A 0.1 mm thick Ag colloidal electrode layer 6 is coated on the other side of the Mo-coated glass substrate 1 as a conductive layer, with a gap between the Ag colloidal electrode layer 6 and the copper-based sulfide thin film 2; the obtained copper-based sulfide solar photocatalytic water splitting hydrogen production thin film photocathode is recorded as ETL-2.

[0045] Example 3

[0046] S1. Dissolve SnCl4·5H2O, CuCl, Zn(CH3COO)2·2H2O, SC(NH2)2, SnCl2·2H2O, Cu(CH3COO)2·H2O, ZnCl2 and SC(NH2)2 in 2-ME solvent respectively and mix them at 60℃ for 90min to obtain a mixed solution. The concentration of SnCl4 in the mixed solution is 0.83M, the concentration of CuCl is 1.42M, the concentration of Zn(CH3COO)2 is 1.0M, the concentration of SC(NH2)2 is 6.4M, and the concentration of SnCl2 is 0.83M. The concentration of Cu(CH3COO)2 is 0.83M, the concentration of Cu(CH3COO)2 is 1.42M, the concentration of ZnCl2 is 1.0M, and the concentration of SC(NH2)2 is 6.4M; the mixed solution is then diluted to half of its original concentration to prepare a copper-based chalcogenide thin film precursor solution, and the copper-based chalcogenide thin film precursor solution is spin-coated on one side of a Mo-coated glass substrate. After each round of spin-coating, an annealing treatment is performed in air at 300°C, and a total of 10 layers are spin-coated; then, a heat treatment is performed at 550°C in a selenium, tin, and argon atmosphere to form a copper-based chalcogenide thin film 2 with a thickness of about 1000nm as a light absorption layer;

[0047] S2, such as Figure 2 As shown, diethylzinc DEZ, tetrakis(dimethylamino)tin TDMASn and deionized water are used as zinc, tin and oxygen precursors, respectively. The temperatures of the diethylzinc DEZ precursor and the H2O precursor are kept at room temperature, while the temperatures of the stainless steel container, the delivery pipe and the reaction chamber for storing the tetrakis(dimethylamino)tin TDMASn precursor are set to 60°C, 100°C and 120°C, respectively. A DMASn precursor and an H2O precursor are introduced into the atomic layer deposition reaction chamber in the order of one cycle. The deposition process includes a 60ms DEZ or TDMASn pulse, a 160ms H2O pulse, and a 5-10s N2 purge. Two layers of ZnO and one layer of SnO2 are formed in each cycle, respectively. A zinc-tin oxide film with a thickness of 0.3nm is formed in each cycle. Atomic layer deposition is performed for a total of 83 cycles, ultimately forming a zinc-tin oxide film 3 with a thickness of 25nm on the copper-based chalcogenide film 2.

[0048] S3, using TiCl4 as a titanium source and H2O as an oxygen source, with the TiCl4 reaction chamber and supply pipeline set to 80°C and 190°C, respectively, and introducing TiCl4 and H2O into the atomic layer deposition reaction chamber in this order for one cycle. The deposition procedure includes a 60ms TiCl4 pulse, a 160ms H2O pulse, and a 5-10s N2 purge. Each cycle forms a TiO2 film with a thickness of 0.07nm. Atomic layer deposition is performed for a total of 100 cycles, ultimately forming a TiO2 layer 4 with a thickness of 7nm on the zinc-tin oxide film 3;

[0049] S4, using an automatic sputtering machine to deposit a Pt promoter at a current of 20 mA for 50 seconds, ultimately forming a Pt layer 5 with a thickness of 10 nm on the TiO2 layer 4;

[0050] S5. A 0.1 mm thick Ag colloidal electrode layer 6 is coated on the other side of the Mo-coated glass substrate 1 as a conductive layer, with a gap between the Ag colloidal electrode layer 6 and the copper-based sulfide thin film 2; the obtained copper-based sulfide solar photocatalytic water splitting hydrogen production thin film photocathode is recorded as ETL-3.

[0051] It can be seen from Examples 1 to 3 that when preparing a zinc tin oxide thin film, the thickness of the zinc tin oxide thin film formed by 17 atomic layer deposition cycles is 5 nm, the thickness of the zinc tin oxide thin film formed by 51 atomic layer deposition cycles is 15 nm, and the thickness of the zinc tin oxide thin film formed by 83 atomic layer deposition cycles is 25 nm. That is, the thicker the zinc tin oxide film, the more water is required, which is one of the reasons for the change in the band gap.

[0052] The copper-based sulfur-based solar photocatalytic water splitting hydrogen production thin film photocathodes prepared in Examples 1 to 3 were tested respectively. The specific test conditions and process are as follows:

[0053] The test was performed using a three-electrode system on an electrochemical workstation. The test sample was clamped on the working electrode, the Pt electrode was clamped on the counter electrode, and the reference electrode was clamped on the Ag / Cl electrode. All three electrodes were placed in a 1M H2SO4 buffer solution. A standard AM1.5G light source was used to illuminate the test sample surface. The test voltage was set to sweep from -0.4 to 0.6 V, and the resulting voltage-current data was collected. The obtained data was substituted into the following formula to calculate the corresponding value:

[0054] V RHE =V Ag / AgCl +0.059×PH+0.199;

[0055]

[0056] V Ag / AgCl is the potential relative to the Ag / AgCl reference electrode and can be converted to the reversible hydrogen electrode (VRHE ) scale; PH represents the pH value of the test solution, P sun Indicates the intensity of AM 1.5G simulated sunlight (100mW / cm 2 ), J ph is the photocurrent density obtained from the test, is the reduction potential of hydrogen ions, which is 0V here RHE The corresponding half-cell solar-to-hydrogen conversion efficiency (HC-STH) can be calculated using the above formula. The current-voltage diagram of ETL-2 and the corresponding half-cell efficiency diagram are shown in Figure 2. Figure 3 As shown, at 0V RHE 29.8mA / cm was achieved under the bias of 2 The current density is 2.5 GHz and the maximum HC-STH efficiency reaches 4%.

[0057] When the CBO is positively offset (CBO>0), that is, the conduction band of the n-type material is lower than that of the p-type material, the photogenerated electrons diffuse from the p-region to the n-region, which will gain additional potential energy reduction, forming an additional driving force, promoting the migration of electrons to the n-region. When the CBO is negatively offset (CBO<0), that is, the conduction band of the n-type material is higher than that of the p-type material, electrons need to overcome a potential barrier to enter the n-region, which may lead to carrier accumulation or recombination, reducing separation efficiency. A moderate offset (CBO≈0-0.4eV) can enhance carrier separation while avoiding recombination caused by excessive interface states.

[0058] The band gap test results and the conduction band matching diagram of copper-based chalcogenides are shown in the figure below. Figure 4 As shown by Figure 4 It can be seen that by configuring ZTO thin films with different thicknesses, their band gaps can be tuned. The band gaps are found to be in the range of 3.5-3.6 eV (3.59 eV for ETL-1, 3.63 eV for ETL-2, and 3.52 eV for ETL-3), compared to 2.4 eV for CdS. This reduces light absorption, allowing more light energy to pass through the electron transport layer and reach the absorption layer. In the case of ETL-3, the negative conduction band offset indicates a "cliff-like" band alignment at the heterojunction interface. Under forward bias conditions, this "cliff" can act as a barrier to injected electrons, potentially increasing the risk of charge carrier recombination and limiting device performance. In contrast, the ETL-1 and ETL-2 configurations exhibit a "spike-like" band alignment (with conduction band offsets of 0.03 eV and 0.06 eV, respectively). The larger spike (larger conduction band offset) in ETL-2 is beneficial to promote the transfer of electrons from the absorber to the electrolyte, reduce the carrier recombination at the absorber / ETL interface, and thus improve the overall performance of the device.

[0059] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. Any technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A copper-based chalcogenide solar photocatalytic water splitting hydrogen production thin film photocathode, comprising a Mo-coated glass substrate, characterized in that: A copper-based chalcogenide film is spin-coated on one side of the upper end surface of the Mo-coated glass substrate as a light absorption layer, a zinc-tin oxide film is deposited on the upper end surface of the copper-based chalcogenide film as an electron transport layer, a TiO2 layer is deposited on the upper end surface of the zinc-tin oxide film as a protective layer, a Pt layer is deposited on the upper end surface of the TiO2 layer as a co-catalyst layer, and an Ag colloidal electrode layer is provided on the other side of the upper end surface of the Mo-coated glass substrate as a conductive layer, with a gap between the Ag colloidal electrode layer and the copper-based chalcogenide film.

2. The copper-based sulfur-based solar photocatalytic water splitting hydrogen production thin film photocathode according to claim 1, characterized in that: The thickness of the copper-based chalcogenide thin film is 500-1500 nm.

3. The copper-based sulfur-based solar photocatalytic water splitting hydrogen production thin film photocathode according to claim 1, characterized in that: The thickness of the zinc tin oxide film is 5-25 nm.

4. The copper-based sulfur-based solar photocatalytic water splitting hydrogen production thin film photocathode according to claim 1, characterized in that: The thickness of the TiO2 layer is 7-14 nm.

5. The copper-based sulfide solar photocatalytic water splitting hydrogen production thin film photocathode according to claim 1, characterized in that: The thickness of the Pt layer is 5-10 nm.

6. The copper-based sulfur-based solar photocatalytic water splitting hydrogen production thin film photocathode according to claim 1, characterized in that: The thickness of the Ag colloidal electrode layer is 0.1 mm.

7. A method for preparing a copper-based sulfur-based solar photocatalytic water splitting hydrogen production thin film photocathode according to claims 1-6, characterized in that: The following steps are involved: S1. Dissolve SnCl4·5H2O, CuCl, Zn(CH3COO)2·2H2O, SC(NH2)2, SnCl2·2H2O, Cu(CH3COO)2·H2O, ZnCl2 and SC(NH2)2 in 2-ME solvent respectively, mix at 60°C for 90 minutes, and then dilute to half of its original concentration to prepare a copper-based chalcogenide thin film precursor solution, spin-coat the copper-based chalcogenide thin film precursor solution on one side of a Mo-coated glass substrate, and perform annealing at 300°C in air after each round of spin coating, and spin-coat 8-12 layers in total; then heat-treat at 550°C in a selenium, tin and argon atmosphere to form a copper-based chalcogenide thin film as a light absorption layer; S2, depositing a zinc tin oxide film with a thickness of 5-25 nm as an electron transport layer on the copper-based chalcogenide film by atomic layer deposition; S3, depositing a TiO2 layer as a protective layer on the zinc tin oxide film by atomic layer deposition; S4, using an automatic sputtering machine to deposit a Pt layer as a promoter layer on the TiO2 layer at a current of 20 mA; S5. A Ag colloidal electrode layer is coated on the other side of the Mo-coated glass substrate as a conductive layer, with a gap between the Ag colloidal electrode layer and the copper-based sulfide thin film; and a copper-based sulfide solar photocatalytic water splitting hydrogen production thin film photocathode is obtained.

8. The copper-based sulfur-based solar photocatalytic water splitting hydrogen production thin film photocathode according to claim 1, characterized in that: The step S2 specifically includes: Diethylzinc DEZ, tetrakis(dimethylamino)tin TDMASn and deionized water were used as zinc, tin and oxygen precursors, respectively. The temperatures of the diethylzinc DEZ precursor and the H2O precursor were kept at room temperature, while the temperatures of the stainless steel container, the delivery pipe and the reaction chamber for storing the tetrakis(dimethylamino)tin TDMASn precursor were set to 50-80°C, 80-120°C and 100-150°C, respectively. The MASn precursor and the H2O precursor are introduced into the atomic layer deposition reaction chamber in the order of one cycle. The deposition procedure includes a 40-80ms DEZ or TDMASn pulse, a 100-160ms H2O pulse and a 5-10s N2 purge. Two layers of ZnO and one layer of SnO2 films are formed in each cycle, and a zinc tin oxide film with a thickness of 0.3nm is formed in each cycle. Atomic layer deposition is set for a total of 17-83 cycles, and finally a zinc tin oxide film with a thickness of 5-25nm is formed on the copper-based chalcogenide film.

9. The copper-based sulfur-based solar photocatalytic water splitting hydrogen production thin film photocathode according to claim 1, characterized in that: The step S3 specifically includes: TiCl4 is used as the titanium source and H2O is used as the oxygen source. The reaction chamber and supply pipeline of TiCl4 are set to 80℃ and 190℃ respectively. TiCl4 and H2O are introduced into the atomic layer deposition reaction chamber in the order of one cycle. The deposition procedure includes a TiCl4 pulse of 40-80ms, an H2O pulse of 100-160ms and an N2 purge of 5-10s. A TiO2 film with a thickness of 0.07nm is formed in each cycle. Atomic layer deposition is set for a total of 100-200 cycles, and finally a TiO2 layer with a thickness of 7-14nm is formed on the zinc tin oxide film.

10. The copper-based sulfur-based solar photocatalytic water splitting hydrogen production thin film photocathode according to claim 1, characterized in that: The step S4 specifically includes: using an automatic sputtering machine to deposit a Pt promoter for 50 seconds at a current of 20 mA, and finally forming a Pt layer with a thickness of 5-10 nm on the TiO2 layer.

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