Z-type heterojunction material and preparation method and application thereof

Abstract

The invention discloses a Z-type heterojunction material and a preparation method and application thereof.The Z-type heterojunction material comprises a conductive substrate, a BiVO4 nanorod and a metal passivation layer which are sequentially distributed in a stacked mode and further comprises Cu2O distributed on the surface of the metal passivation layer, and the Cu2O, the BiVO4 nanorod and the metal passivation layer form a heterojunction. According to the scheme, a BiVO4 nanorod array grows on the surface of a conductive substrate, and a metal passivation layer covers the BiVO4 nanorod array. And the structure and Cu2O jointly form a Z-type heterojunction. The heterojunction photoelectrode has relatively high electron transport kinematic mechanical properties, can realize high-efficiency photoelectrochemical water decomposition hydrogen production, and shows excellent photoelectric hydrogen production efficiency.

Description

Technical Field

[0001] This invention relates to the field of photoelectrocatalysis technology, specifically to a Z-type heterojunction material, its preparation method, and its application. Background Technology

[0002] With technological advancements and social development, energy issues are becoming increasingly prominent. The environmental pressures and depletion of reserves brought about by traditional non-renewable energy sources such as coal, oil, and natural gas are becoming increasingly severe. Therefore, research on new renewable green energy sources is particularly important. Hydrogen energy, as a clean energy source, requires the development of efficient and high-performance hydrogen production catalytic systems, which has become an urgent research need. Photoelectrochemical (PEC) water splitting technology, due to its sustainability and high efficiency, is considered a promising hydrogen production solution. This technology utilizes photoanode materials to absorb light energy, exciting electrons and holes to participate in the redox reaction of water splitting, thereby achieving the production of hydrogen and oxygen.

[0003] However, the photoanode drives the water splitting reaction (2H2O→O2+4H2O). + +4e - During the photoelectrochemical water splitting process, challenges remain, including slow reaction kinetics, short hole diffusion length, low carrier mobility, and severe carrier recombination. These factors make photoanode research highly challenging. Currently, common photoanode materials generally suffer from limitations such as rapid surface charge recombination and slow oxidation reaction kinetics, often requiring the application of additional bias voltage to promote charge separation and transfer. Therefore, developing novel high-performance photoelectrode materials is of great significance for achieving efficient photoelectrochemical water splitting. Summary of the Invention

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a Z-type heterojunction material that exhibits high electron transport dynamics during photoelectrochemical water splitting, enabling photoelectrochemical hydrogen production with high photoelectrochemical hydrogen production efficiency.

[0005] The present invention also proposes a method for preparing the above-mentioned Z-type heterojunction material.

[0006] This invention also proposes the application of the aforementioned Z-type heterojunction material.

[0007] According to one aspect of the present invention, a Z-type heterojunction material is provided, comprising a conductive substrate, BiVO4 nanorods and a metal passivation layer stacked sequentially, and further comprising Cu2O distributed on the surface of the metal passivation layer, wherein the Cu2O forms a heterojunction with the BiVO4 nanorods and the metal passivation layer.

[0008] The Z-type heterojunction material according to embodiments of the present invention has at least the following beneficial effects: In the present invention, a BiVO4 nanorod array is grown on the surface of a conductive substrate, and a metal passivation layer is covered on it. This structure, together with Cu2O, constitutes a Z-type heterojunction. This heterojunction photoelectrode has high electron transport dynamics, enabling efficient photoelectrochemical water splitting for hydrogen production, exhibiting excellent photoelectrochemical hydrogen production efficiency.

[0009] According to some embodiments of the present invention, the particle size of the BiVO4 nanorods is 200~400 nm.

[0010] According to some embodiments of the present invention, the metal passivation layer is made of at least one of Au, Ag, Al, Cr or Cu.

[0011] According to some embodiments of the present invention, the thickness of the metal passivation layer is 5~40 nm.

[0012] According to some embodiments of the present invention, the particle size of the heterojunction is 200~400 nm.

[0013] According to some embodiments of the present invention, the sheet resistance of the conductive substrate is below 15Ω.

[0014] According to some embodiments of the present invention, the material of the conductive substrate is selected from at least one of FTO conductive glass or Si substrate.

[0015] According to a second aspect of the present invention, a method for preparing the above-mentioned Z-type heterojunction material is provided, comprising the following steps: S1. Using a solution containing bismuth salt, potassium iodide, and benzoquinone as electrolyte I, and a conductive substrate as the working electrode, BiOI is formed on the surface of the conductive substrate by electrochemical deposition. A vanadium acetylacetonate solution is added to the surface of the BiOI, and the substrate is annealed to remove V2O5, thereby obtaining intermediate material I. The pH of electrolyte I is 1.6 to 1.9. S2. Using metal materials as metal raw materials, and using the intermediate material I obtained in step S1 as an electrode, a metal passivation layer is formed on the BiVO4 nanorods by hot evaporation to obtain intermediate material II. S3. Using a solution containing copper acetate and sodium acetate as electrolyte II, and the intermediate material II obtained in step S2 as the working electrode, a Z-type heterojunction material is obtained by electrochemical deposition.

[0016] Therefore, the preparation method of the present invention can be obtained by two-step electrochemical deposition and one-step thermal evaporation of metal passivation layer. The method is relatively simple and can be used for large-scale preparation.

[0017] According to some embodiments of the present invention, the annealing temperature is 400~700°C.

[0018] According to some embodiments of the present invention, the annealing time is 0.5 to 5 hours.

[0019] According to some embodiments of the present invention, the metal raw material is at least one of Au, Ag, Al, Cr or Cu.

[0020] According to some embodiments of the present invention, the metal raw material is at least one of Au or Al.

[0021] According to some embodiments of the present invention, the thickness of the metal passivation layer is 5~40 nm.

[0022] According to some embodiments of the present invention, step S1 further includes adjusting the pH of electrolyte I to 1.6-1.9 using nitric acid.

[0023] According to some embodiments of the present invention, in electrolyte I, the concentration of the bismuth salt is 3-5 mM, the concentration of potassium iodide is 0.3-0.6 M, and the concentration of benzoquinone is 0.1-0.4 M.

[0024] According to some embodiments of the present invention, the pH of electrolyte II is 4.5 to 5.5. For example, it is 5.

[0025] According to some embodiments of the present invention, electrolyte II contains copper acetate, sodium acetate and a pH adjuster.

[0026] According to some embodiments of the present invention, the pH adjuster is an acetic acid solution.

[0027] According to some embodiments of the present invention, the concentration of acetic acid in the acetic acid solution is 0.8~1.2 mol / L, such as 1 mol / L.

[0028] According to some embodiments of the present invention, electrolyte II contains copper acetate, sodium acetate and acetic acid.

[0029] According to some embodiments of the present invention, in electrolyte II, the concentration of copper acetate is 1-4 mmol / L and the concentration of sodium acetate is 8-16 mmol / L.

[0030] According to some embodiments of the present invention, V2O5 is removed in step S1 by soaking in an alkaline solution (such as sodium hydroxide).

[0031] According to some embodiments of the present invention, the electrochemical deposition voltage in step S1 is -0.12V to -0.1V vs. Ag / AgCl.

[0032] According to some embodiments of the present invention, the electrochemical deposition voltage in step S3 is -1.2V to -0.4V vs. Ag / AgCl.

[0033] According to some embodiments of the present invention, in step S1 or step S3, the electrochemical deposition method further includes a counter electrode and a reference electrode.

[0034] According to some embodiments of the present invention, the counter electrode is selected from Pt electrodes.

[0035] According to some embodiments of the present invention, the reference electrode is selected from an Ag / AgCl electrode.

[0036] According to a third aspect of the present invention, the application of the above-described Z-type heterojunction material or the Z-type heterojunction material prepared by the above method in a photoelectrocatalytic water splitting system is provided.

[0037] According to a third aspect of the present invention, a photoelectrode is also provided, wherein the raw materials for preparing the photoelectrode include the above-described Z-type heterojunction material or the Z-type heterojunction material prepared by the above method.

[0038] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0039] Figure 1 This is a top SEM view of the conductive glass with BiVO4 nanorods formed in Example 1 of the present invention.

[0040] Figure 2 This is a top SEM view of the Z-shaped heterojunction prepared in Embodiment 1 of the present invention.

[0041] Figure 3 This is a comparison chart of the linear scanning curves of the photoelectrode materials in Embodiment 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0042] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the embodiments are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available. Unless otherwise specified, the same parameter value is the same in all embodiments. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0043] In the description of this invention, references to terms such as "some embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] In the description of this invention, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0045] Unless otherwise specified, the operations in the following examples and comparative examples are the same as those in Example 1.

[0046] Example 1 This example provides a Z-type heterojunction material, comprising a conductive substrate, BiVO4 nanorods, a metal passivation layer, and Cu2O. The BiVO4 nanorods are located on the surface of the conductive substrate; the metal passivation layer is located on top of the BiVO4 nanorods; Cu2O forms a heterojunction with the BiVO4 nanorods and the metal passivation layer; and Cu2O is distributed on the BiVO4 nanorods and the metal passivation layer. The preparation method includes the following steps: Substrate selection: FTO conductive glass (sheet resistance <15Ω) is used.

[0047] S1. Using an electrochemical deposition method, BiOI was deposited onto FTO using a solution of 4 mM bismuth nitrate, 0.4 M potassium iodide, and 0.2 M benzoquinone as the electrolyte. FTO conductive glass, Pt wire, and Ag / AgCl were used as the working electrode, counter electrode, and reference electrode, respectively. BiOI was deposited onto FTO for 400 s under a bias voltage of -0.12 V vs. Ag / AgCl. Then, 20 μL of a 0.2 M vanadium acetylacetonate dimethyl sulfoxide solution was added to its surface, followed by annealing at 450 °C in an oxygen atmosphere for 2 h. Finally, the nanorods were immersed in 1 M NaOH solution for 30 min to remove V₂O₅, yielding BiVO₄ nanorods. S2. Using thermal evaporation deposition method, with metal raw material Al as passivation layer, the conductive glass with BiVO4 nanorods obtained in step S1 is placed into a thermal evaporation deposition instrument to obtain a metal passivation layer Al layer (thickness of about 10nm). S3. Using electrochemical deposition, a solution containing 2mM copper acetate and 8M sodium acetate is used as the electrolyte. The pH of the electrolyte is adjusted to 5 by using 1M acetic acid solution. The conductive glass containing the metal passivation layer and BiVO4 nanorods obtained in step S2, Pt wire, and Ag / AgCl are used as the working electrode, counter electrode, and reference electrode, respectively. Cu2O is deposited on the BiVO4 nanorods with the metal passivation layer obtained in step S2 for 400s under a bias voltage of -0.8V vs. Ag / AgCl, forming a Z-shaped heterojunction (BiVO4 / Al / Cu2O nanorods).

[0048] The conductive glass with BiVO4 nanorods prepared in step S1 of this invention was subjected to SEM analysis, and the results are as follows: Figure 1 As shown, the particle size of BiVO4 nanorods is approximately 300 nm.

[0049] Furthermore, the Z-shaped heterojunction formed in step S3 of the present invention was subjected to SEM detection, and the results are as follows: Figure 2 As shown, the particle size of BiVO4 / Al / Cu2O nanorods is approximately 270 nm.

[0050] Furthermore, the Z-shaped heterojunction material prepared in Example 1 of this invention was used for photoelectrochemical water splitting. The prepared Z-shaped heterojunction material was fabricated into a photoelectrode. Photoelectrochemical tests were performed using an electrochemical workstation, specifically as follows: a 0.5 mol / L Na3PO4 (pH≈9) solution was used as the electrolyte, the prepared photoelectrode was used as the anode, Ag / AgCl was used as the reference electrode, Pt wire was used as the cathode, and a 300W Xe lamp (light intensity ~100mW / cm²) was used. 2 Using the photoelectrode as a light source, the photocurrent density-bias voltage curve was obtained. At a bias voltage of 1.23V vs. RHE, the photocurrent density was 5.08 mA / cm². 2 .

[0051] Example 2 This example provides a Z-type heterojunction material, comprising a conductive substrate, BiVO4 nanorods, a metal passivation layer, and Cu2O. The BiVO4 nanorods are located on the surface of the conductive substrate; the metal passivation layer is located on top of the BiVO4 nanorods; Cu2O forms a heterojunction with the BiVO4 nanorods and the metal passivation layer; and Cu2O is distributed on the BiVO4 nanorods and the metal passivation layer. The preparation method includes the following steps: Substrate selection: FTO conductive glass (sheet resistance <15Ω) is used.

[0052] S1. Using an electrochemical deposition method, BiOI was deposited onto FTO using a solution of 4 mM bismuth nitrate, 0.4 M potassium iodide, and 0.2 M benzoquinone as the electrolyte. FTO conductive glass, Pt wire, and Ag / AgCl were used as the working electrode, counter electrode, and reference electrode, respectively. BiOI was deposited onto FTO for 400 s under a bias voltage of -0.12 V vs. Ag / AgCl. Then, 20 μL of a 0.2 M vanadium acetylacetonate dimethyl sulfoxide solution was added to its surface, followed by annealing at 450 °C in an oxygen atmosphere for 2 h. Finally, the nanorods were immersed in 1 M NaOH solution for 30 min to remove V₂O₅, yielding BiVO₄ nanorods. S2. Using a thermal evaporation method, with Au as the passivation layer, the conductive glass with BiVO4 nanorods obtained in step S1 is placed in a thermal evaporation apparatus to perform thermal evaporation to obtain a metal passivation layer Au (thickness of about 10nm). S3. Using an electrochemical deposition method, a solution containing 2mM copper acetate and 8M sodium acetate is used as the electrolyte. The pH of the electrolyte is adjusted to 5 by using a 1M acetic acid solution. The conductive glass containing the metal passivation layer and BiVO4 nanorods obtained in step S2, Pt wire, and Ag / AgCl are used as the working electrode, counter electrode, and reference electrode, respectively. Cu2O is deposited onto the BiVO4 nanorods with the metal passivation layer obtained in step S2 for 400s under a bias voltage of -0.8V vs. Ag / AgCl, forming a Z-shaped heterojunction (BiVO4 / Au / Cu2O nanorods), thus obtaining the Z-shaped heterojunction material.

[0053] The Z-shaped heterojunction material of Example 2 was used for photoelectrochemical water splitting. The prepared Z-shaped heterojunction material was fabricated into a photoelectrode. Photoelectrochemical tests were performed using an electrochemical workstation, specifically as follows: a 0.5 mol / L Na3PO4 solution (pH≈9) was used as the electrolyte; the prepared photoelectrode was used as the anode; Ag / AgCl was used as the reference electrode; Pt wire was used as the cathode; and a 300W Xe lamp (light intensity ~100mW / cm²) was used. 2 Using the photoelectrode as a light source, the photocurrent density-bias voltage curve was obtained. The linear sweep curve of the Z-type heterojunction material shows a photocurrent density of 3.81 mA / cm² at a bias voltage of 1.23 V vs. RHE. 2 .

[0054] Example 3 This example provides a Z-type heterojunction material, comprising a conductive substrate, BiVO4 nanorods, a metal passivation layer, and Cu2O. The BiVO4 nanorods are located on the surface of the conductive substrate; the metal passivation layer is located on top of the BiVO4 nanorods; Cu2O forms a heterojunction with the BiVO4 nanorods and the metal passivation layer; and Cu2O is distributed on the BiVO4 nanorods and the metal passivation layer. The preparation method includes the following steps: Substrate selection: FTO conductive glass (sheet resistance <15Ω) is used.

[0055] S1. Using an electrochemical deposition method, BiOI was deposited onto FTO using a solution of 4 mM bismuth nitrate, 0.4 M potassium iodide, and 0.2 M benzoquinone as the electrolyte. FTO conductive glass, Pt wire, and Ag / AgCl were used as the working electrode, counter electrode, and reference electrode, respectively. BiOI was deposited onto FTO for 400 s under a bias voltage of -0.12 V vs. Ag / AgCl. Then, 20 μL of a 0.2 M vanadium acetylacetonate dimethyl sulfoxide solution was added to its surface, followed by annealing at 450 °C in an oxygen atmosphere for 2 h. Finally, the nanorods were immersed in 1 M NaOH solution for 30 min to remove V₂O₅, yielding BiVO₄ nanorods. S2. Using a thermal evaporation method, with Ag metal as the passivation layer, the conductive glass with BiVO4 nanorods obtained in step S1 is placed in a thermal evaporation apparatus to perform thermal evaporation to obtain a metal passivation layer Ag layer (thickness of about 10nm). S3. Using an electrochemical deposition method, a solution containing 2mM copper acetate and 8M sodium acetate was used as the electrolyte. The pH of the electrolyte was adjusted to 5 using a 1M acetic acid solution. The conductive glass containing the metal passivation layer and BiVO4 nanorods obtained in step S2, Pt wire, and Ag / AgCl were used as the working electrode, counter electrode, and reference electrode, respectively. Cu2O was deposited onto the BiVO4 nanorods with the metal passivation layer obtained in step S2 for 400s under a bias voltage of -0.8V vs. Ag / AgCl, thus obtaining a Z-type heterojunction (BiVO4 / Ag / Cu2O nanorods) and a Z-type heterojunction material.

[0056] The Z-shaped heterojunction material of Example 3 was used for photoelectrochemical water splitting. The prepared Z-shaped heterojunction material was fabricated into a photoelectrode. Photoelectrochemical tests were performed using an electrochemical workstation, specifically as follows: a 0.5 mol / L Na3PO4 solution (pH≈9) was used as the electrolyte; the prepared photoelectrode was used as the anode; Ag / AgCl was used as the reference electrode; Pt wire was used as the cathode; and a 300W Xe lamp (light intensity ~100mW / cm²) was used. 2 Using this as a light source, the photocurrent density-bias curve was obtained. The linear sweep curve of the Z-type heterojunction material shows a photocurrent density of 3.51 mA / cm² at a bias voltage of 1.23 V vs. RHE. 2 .

[0057] Example 4 This example provides a Z-type heterojunction material, comprising a conductive substrate, BiVO4 nanorods, a metal passivation layer, and Cu2O. The BiVO4 nanorods are located on the surface of the conductive substrate; the metal passivation layer is located on top of the BiVO4 nanorods; Cu2O forms a heterojunction with the BiVO4 nanorods and the metal passivation layer; and Cu2O is distributed on the BiVO4 nanorods and the metal passivation layer. The preparation method includes the following steps: Substrate selection: FTO conductive glass (sheet resistance <15Ω) is used.

[0058] S1. Using an electrochemical deposition method, BiOI was deposited onto FTO using a solution of 4 mM bismuth nitrate, 0.4 M potassium iodide, and 0.2 M benzoquinone as the electrolyte. FTO conductive glass, Pt wire, and Ag / AgCl were used as the working electrode, counter electrode, and reference electrode, respectively. BiOI was deposited onto FTO for 400 s under a bias voltage of -0.12 V vs. Ag / AgCl. Then, 20 μL of a 0.2 M vanadium acetylacetonate dimethyl sulfoxide solution was added to its surface, followed by annealing at 450 °C in an oxygen atmosphere for 2 h. Finally, the nanorods were immersed in 1 M NaOH solution for 30 min to remove V₂O₅, yielding BiVO₄ nanorods. S2. Using a thermal evaporation method, with Cu as the passivation layer, the conductive glass with BiVO4 nanorods obtained in step S1 is placed in a thermal evaporation apparatus to perform thermal evaporation to obtain a Cu metal passivation layer (with a thickness of about 10 nm). S3. Using an electrochemical deposition method, a solution containing 2mM copper acetate and 8M sodium acetate was used as the electrolyte. The pH of the electrolyte was adjusted to 5 using a 1M acetic acid solution. The conductive glass containing the metal passivation layer and BiVO4 nanorods obtained in step S2, Pt wire, and Ag / AgCl were used as the working electrode, counter electrode, and reference electrode, respectively. Cu2O was deposited onto the BiVO4 nanorods with the passivation layer obtained in step S2 for 400s under a bias voltage of -0.8V vs. Ag / AgCl, thus obtaining a Z-type heterojunction (BiVO4 / Cu / Cu2O nanorods) and a Z-type heterojunction material.

[0059] The Z-shaped heterojunction material from Example 4 was used for photoelectrochemical water splitting. The prepared Z-shaped heterojunction material was fabricated into a photoelectrode. Photoelectrochemical tests were performed using an electrochemical workstation, specifically as follows: a 0.5 mol / L Na3PO4 solution (pH≈9) was used as the electrolyte; the prepared photoelectrode served as the anode; Ag / AgCl was used as the reference electrode; Pt wire served as the cathode; and a 300W Xe lamp (light intensity ~100mW / cm²) was used. 2 Using the photoelectrode as a light source, the photocurrent density-bias voltage curve was obtained. The linear sweep curve of the Z-type heterojunction material shows a photocurrent density of 3.40 mA / cm² at a bias voltage of 1.23 V vs. RHE. 2 .

[0060] Example 5 This example provides a Z-type heterojunction material, comprising a conductive substrate, BiVO4 nanorods, a metal passivation layer, and Cu2O. The BiVO4 nanorods are located on the surface of the conductive substrate; the metal passivation layer is located on top of the BiVO4 nanorods; Cu2O forms a heterojunction with the BiVO4 nanorods and the metal passivation layer; and Cu2O is distributed on the BiVO4 nanorods and the metal passivation layer. The preparation method includes the following steps: Substrate selection: FTO conductive glass (sheet resistance <15Ω) is used.

[0061] S1. Using an electrochemical deposition method, BiOI was deposited onto FTO using a solution of 4 mM bismuth nitrate, 0.4 M potassium iodide, and 0.2 M benzoquinone as the electrolyte. FTO conductive glass, Pt wire, and Ag / AgCl were used as the working electrode, counter electrode, and reference electrode, respectively. BiOI was deposited onto FTO for 400 s under a bias voltage of -0.12 V vs. Ag / AgCl. Then, 20 μL of a 0.2 M vanadium acetylacetonate dimethyl sulfoxide solution was added to its surface, followed by annealing at 450 °C in an oxygen atmosphere for 2 h. Finally, the nanorods were immersed in 1 M NaOH solution for 30 min to remove V₂O₅, yielding BiVO₄ nanorods. S2. Using a thermal evaporation method, with Cr as the passivation layer, the conductive glass with BiVO4 nanorods obtained in step S1 is placed in a thermal evaporation apparatus to perform thermal evaporation to obtain a Cr passivation layer (with a thickness of about 10 nm). S3. Using an electrochemical deposition method, a solution containing 2mM copper acetate and 8M sodium acetate was used as the electrolyte. The pH of the electrolyte was adjusted to 5 using a 1M acetic acid solution. The conductive glass containing the metal passivation layer and BiVO4 nanorods obtained in step S2, Pt wire, and Ag / AgCl were used as the working electrode, counter electrode, and reference electrode, respectively. Cu2O was deposited onto the BiVO4 nanorods with the passivation layer obtained in step S2 for 400s under a bias voltage of -0.8V vs. Ag / AgCl, thus obtaining a Z-shaped heterojunction (BiVO4 / Ag / Cu2O nanorods).

[0062] The Z-shaped heterojunction material of Example 5 was used for photoelectrochemical water splitting. The prepared Z-shaped heterojunction material was fabricated into a photoelectrode. Photoelectrochemical tests were performed using an electrochemical workstation, specifically as follows: a 0.5 mol / L Na3PO4 solution (pH≈9) was used as the electrolyte; the prepared photoelectrode was used as the anode; Ag / AgCl was used as the reference electrode; Pt wire was used as the cathode; and a 300W Xe lamp (light intensity ~100mW / cm²) was used. 2Using the photoelectrode as a light source, the photocurrent density-bias voltage curve was obtained. The linear sweep curve of the Z-type heterojunction material shows a photocurrent density of 3.42 mA / cm² at a bias voltage of 1.23 V vs. RHE. 2 .

[0063] Comparative Example 1 This example provides a photoelectrode material, the preparation method of which is as follows: Substrate selection: FTO conductive glass (sheet resistance <15Ω) is used.

[0064] An electrochemical deposition method was used, with 4 mM bismuth nitrate, 0.4 M potassium iodide, and 0.2 M benzoquinone solution as the electrolyte. FTO conductive glass, Pt wire, and Ag / AgCl were used as the working electrode, counter electrode, and reference electrode, respectively. BiOI was deposited onto FTO for 400 s under a bias voltage of -0.12 V vs. Ag / AgCl. Then, 20 μL of 0.2 M vanadium acetylacetonate dimethyl sulfoxide solution was dropped onto its surface, and it was annealed at 450 °C in an oxygen atmosphere for 2 h. Finally, it was immersed in 1 M NaOH solution for 30 min to remove V2O5, yielding BiVO4 nanorods.

[0065] The photoelectrode material (conductive glass with BiVO4 nanorods) prepared in Comparative Example 1 was used for photoelectrochemical water splitting. The prepared Z-shaped heterojunction material was used to fabricate the photoelectrode. Photoelectrochemical tests were performed using an electrochemical workstation, specifically: a 0.5 mol / L Na3PO4 solution (pH≈9) was used as the electrolyte; the prepared photoelectrode was used as the anode; Ag / AgCl was used as the reference electrode; Pt wire was used as the cathode; and a 300W Xe lamp (light intensity ~100mW / cm²) was used. 2 Using the photoelectrode as a light source, the photocurrent density-bias voltage curve was obtained. With a bias voltage of 1.23V vs. RHE, the photocurrent density was 0.86 mA / cm². 2 .

[0066] The linear scanning curves of the photoelectrodes in Example 1 and Comparative Example 1 are shown in the figure below. Figure 3 As shown, from Figure 3 It can be seen that the photocurrent density of Comparative Example 1 is 0.86 mA / cm² at a voltage of 1.23 V / RHE. 2 The photocurrent density of embodiment 1 is 5.08 mA / cm². 2 It is about 5.9 times higher than that of control sample 1, and the higher current density is more conducive to enhancing the charge transport of the photoelectrode and enhancing the efficiency of photoelectric hydrogen production.

[0067] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A Z-type heterojunction material, characterized in that: It includes a conductive substrate, BiVO4 nanorods and a metal passivation layer stacked sequentially, and also includes Cu2O distributed on the surface of the metal passivation layer, wherein the Cu2O forms a heterojunction with the BiVO4 nanorods and the metal passivation layer.

2. The Z-type heterojunction material according to claim 1, characterized in that: The BiVO4 nanorods have a particle size of 200~400nm; and / or the metal passivation layer is made of at least one of Au, Ag, Al, Cr or Cu.

3. The Z-type heterojunction material according to claim 1, characterized in that: The thickness of the metal passivation layer is 5~40nm; and / or the particle size of the heterojunction is 200~400nm.

4. The method for preparing the Z-type heterojunction material according to any one of claims 1 to 3, characterized in that: Includes the following steps: S1. Using a solution containing bismuth salt, potassium iodide, and benzoquinone as electrolyte I, and a conductive substrate as the working electrode, BiOI is formed on the surface of the conductive substrate by electrochemical deposition. An acetylacetone vanadium oxide solution is added to the surface of the BiOI and annealed to obtain intermediate material I; wherein, the pH of electrolyte I is 1.6~1.

9. S2. Using metal materials as metal raw materials, and using the intermediate material I obtained in step S1 as an electrode, a metal passivation layer is formed on the BiVO4 nanorods by hot evaporation to obtain intermediate material II. S3. Using a solution containing copper acetate and sodium acetate as electrolyte II, and the intermediate material II obtained in step S2 as the working electrode, a Z-type heterojunction material is obtained by electrochemical deposition.

5. The method for preparing the Z-type heterojunction material according to claim 4, characterized in that: The annealing temperature is 400~700℃; and / or the annealing time is 0.5~5h.

6. The method for preparing the Z-type heterojunction material according to claim 4, characterized in that: Electrolyte I contains bismuth salt, potassium iodide, and benzoquinone, wherein the concentration of bismuth salt is 3-5 mM, the concentration of potassium iodide is 0.3-0.6 M, and the concentration of benzoquinone is 0.1-0.4 M; and / or, the electrochemical deposition voltage in step S1 is -0.12V to -0.1V vs. Ag / AgCl.

7. The method for preparing the Z-type heterojunction material according to claim 4, characterized in that: The pH of electrolyte II is 4.5~5.5, and electrolyte II contains copper acetate, sodium acetate and pH adjuster; and / or, the electrochemical deposition voltage in step S3 is -1.2V~-0.4V vs. Ag / AgCl.

8. The method for preparing the Z-type heterojunction material according to claim 4, characterized in that: Electrolyte II contains copper acetate, sodium acetate, and acetic acid. The concentration of copper acetate is 1-4 mM, and the concentration of sodium acetate is 8-16 mM.

9. The application of the Z-type heterojunction material as described in any one of claims 1 to 3 or the Z-type heterojunction material prepared by the preparation method as described in any one of claims 4 to 8 in a photoelectrocatalytic water splitting system.

10. A photoelectrode, characterized in that: The raw materials for preparing the photoelectrode include the Z-type heterojunction material as described in any one of claims 1 to 3 or the Z-type heterojunction material prepared by the preparation method as described in any one of claims 4 to 8.

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