A method for constructing a Z-type photocatalytic water splitting reaction system based on a perovskite oxysulfide

Abstract

The application discloses a construction method of a Z-type photocatalytic water decomposition reaction system based on a perovskite oxysulfide. The application constructs a Z-type photocatalytic full water decomposition reaction system by taking a perovskite oxysulfide with visible light absorption characteristics as a hydrogen evolution photocatalyst and taking a Co-based metal complex as an oxidation / reduction ion pair. In the application, the Co-based complex electron transport medium has a matched oxidation potential and a stable oxidation state with the oxysulfide, so that the Co-based complex electron transport medium has good activity and stability in the Z-type photocatalytic full water decomposition system. The perovskite oxysulfide such as Y2Ti2O5S2 / Sm2Ti2O5S2 can absorb up to 650 nm / 590 nm visible light, which greatly improves the absorption efficiency of sunlight, and the perovskite oxysulfide has a crystal face selective charge separation characteristic, which helps to improve the carrier separation efficiency and improve the Z-type photocatalytic full water decomposition reaction activity.

Description

Technical Field

[0001] This invention relates to the development and expansion of novel photocatalytic water splitting reaction systems, and particularly to a method for constructing a Z-type photocatalytic water splitting reaction system based on perovskite oxysulfides, belonging to the fields of solar energy conversion and green hydrogen energy technology. Technical Background

[0002] Hydrogen utilization is characterized by its pollution-free nature and high energy density. The development of green hydrogen energy holds promise for reducing dependence on petroleum resources and decreasing greenhouse gas emissions. Solar-powered photocatalytic water splitting for hydrogen production has attracted significant attention, providing a feasible solution for current green hydrogen energy production. For a single-particle, one-step photocatalytic water splitting process, the photocatalyst needs a suitable band-edge potential to simultaneously drive the redox reaction of water, which places high demands on the physical properties of the catalyst material. Inspired by natural photosynthesis, the Z-type photocatalytic reaction pathway based on dual-semiconductor particles has garnered widespread attention. This pathway couples two different semiconductors to separately carry out the oxygen evolution reaction (OER) of water oxidation and the hydrogen evolution reaction (HER) of water reduction, and achieves charge balance on the two semiconductors by introducing appropriate electron conduction media. Compared to single-particle one-step excitation, the band gap of the catalyst based on the Z-type photocatalytic reaction pathway does not need to simultaneously cross the evolution potentials of hydrogen and oxygen, thus reducing the thermodynamic requirements of the catalyst material and expanding the range of semiconductor choices. Therefore, developing an efficient Z-type photocatalytic water splitting reaction system has significant practical application prospects.

[0003] Perovskite oxysulfide semiconductors are an important class of photocatalyst materials. Past research has primarily focused on their application in photocatalytic hydrogen or oxygen production half-reactions. Although a few reports have documented their use in Z-type photocatalytic water splitting systems, their activity is generally low. This is mainly due to the lack of suitable redox ion pairs to efficiently drive the water splitting reaction on the catalyst surface. Therefore, it is necessary to develop a redox ion pair suitable for perovskite oxysulfide Z-type photocatalytic systems to achieve good hydrogen production activity through water splitting. Summary of the Invention

[0004] The purpose of this invention is to develop an oxidation / reduction ion pair applicable to the perovskite oxysulfide Z-type photocatalytic reaction system, so as to construct an efficient charge transport pathway, improve the photocatalytic water splitting reaction activity of the system, and achieve the goal of photo-driven efficient preparation of hydrogen and oxygen.

[0005] To achieve the above objectives, the present invention provides a method for constructing a Z-type photocatalytic water splitting reaction system based on perovskite oxysulfides, comprising the following steps:

[0006] Step 1): Prepare perovskite oxysulfide semiconductor particles and support them with corresponding co-catalysts to serve as hydrogen evolution photocatalysts in the Z-type photocatalytic water splitting reaction system.

[0007] Step 2): Prepare at least one of the following catalysts with photocatalytic oxygen production activity: Mo:BiVO4, TaON and GaN:ZnO and support the corresponding co-catalyst, so as to serve as the oxygen evolution photocatalyst in the Z-type photocatalytic water splitting reaction system.

[0008] Step 3): Add the hydrogen evolution photocatalyst obtained in Step 1 and the oxygen evolution photocatalyst obtained in Step 2 to water, and add a Co-based metal complex redox ion pair as an electron transport medium to complete the construction of the Z-type photocatalytic water splitting reaction system.

[0009] Preferably, the perovskite oxysulfide semiconductor particles in step 1) are at least one of Y2Ti2O5S2 and Sm2Ti2O5S2;

[0010] And / or, the perovskite oxysulfide semiconductor particles in step 1) are prepared by molten salt-assisted solid-state method, solid-state synthesis method or hydrogen sulfide sulfidation method.

[0011] And / or, the Co-based metal complex redox ion pair in step 3) is cobalt o-phenanthroline (chemical formula [Co(phen)3)). 3+ / 2+ ) and cobalt bipyridine (chemical formula [Co(bpy)3) 3+ / 2+ At least one of the redox couples.

[0012] Preferably, in step 1), the perovskite oxysulfide semiconductor particles are prepared by molten salt-assisted solid-state method. The specific preparation process includes: mixing and grinding Y2O3 or Sm2O3, TiS2, TiO2 and molten salt in an inert gas atmosphere at a molar ratio of 1:1.05:0.95:6, then adding sulfur powder, vacuuming, and calcining; after natural cooling, washing to remove the molten salt and drying to obtain the final product.

[0013] Preferably, the cocatalyst in step 1) is a metal oxide cocatalyst and / or a noble metal cocatalyst, wherein the metal oxide cocatalyst is selected from at least one of RuO2, IrO2, oxides of manganese, oxides of cobalt and oxides of nickel.

[0014] And / or, after supporting the co-catalyst in step 1), the method further includes: preparing a surface oxide protective layer Rh. 2-y Cr y The steps for preparing O3. The oxide protective layer can be prepared using photodeposition.

[0015] And / or, the molten salt in step 1) is a chloride salt of an alkali metal or an alkaline earth metal.

[0016] Preferably, the co-catalyst in step 2) is a metal oxide and / or a noble metal co-catalyst, wherein the metal oxide co-catalyst is selected from at least one of RuO2, IrO2, oxides of manganese, oxides of cobalt and oxides of nickel.

[0017] Preferably, the hydrogen evolution photocatalyst in step 1) is Rh 2-y Cr y O3@Au-IrO2 / Y2Ti2O5S2 and Rh 2- y Cr y At least one of O3@Au-IrO2 / Sm2Ti2O5S2;

[0018] And / or, the oxygen evolution photocatalyst in step 2) is CoO x At least one of / Mo:BiVO4, Au-IrO2 / TaON, and IrO2 / GaN:ZnO.

[0019] Preferably, in the Z-type photocatalytic water splitting reaction system constructed in step 4), the concentrations of the hydrogen evolution photocatalyst and the oxygen evolution photocatalyst are 0.25–5 g / L; their concentration ratio is 1:0.5–4; and the concentration of the Co-based metal complex redox ion pair is 0.01–1 mmol / L. More preferably, the concentrations of the hydrogen evolution photocatalyst and the oxygen evolution photocatalyst are 0.5–1 g / L, and the most preferably, the concentration ratio is 1:1.5.

[0020] The present invention also provides a catalyst composition comprising a hydrogen evolution photocatalyst, an oxygen evolution photocatalyst, and a Co-based metal complex redox ion pair;

[0021] The hydrogen evolution photocatalyst is Rh 2-y Cr y O3@Au-IrO2 / Y2Ti2O5S2 and Rh 2-y Cr y At least one of O3@Au-IrO2 / Sm2Ti2O5S2;

[0022] The oxygen evolution photocatalyst is CoO. x At least one of / Mo:BiVO4, Au-IrO2 / TaON and IrO2 / GaN:ZnO;

[0023] The Co-based metal complex redox ion pair is o-phenanthroline cobalt (chemical formula [Co(phen)3]). 3+ / 2+ ) and cobalt bipyridine (chemical formula [Co(bpy)3)3+ / 2+ At least one of the redox couples.

[0024] The present invention also provides the application of the above-described catalyst composition in the photocatalytic water splitting reaction.

[0025] Preferably, in the photocatalytic water splitting reaction: the concentration of the hydrogen evolution photocatalyst and the oxygen evolution photocatalyst is 0.25–5 g / L; the concentration ratio of the hydrogen evolution photocatalyst to the oxygen evolution photocatalyst is 1:0.5–4; and the concentration of the Co-based metal complex redox ion pair is 0.01–1 mmol / L. More preferably, the concentration of the hydrogen evolution photocatalyst and the oxygen evolution photocatalyst is 0.5–1 g / L, and the most preferably, the concentration ratio is 1:1.5.

[0026] This invention also provides an application of Co-based metal complex redox ion pairs as electron transport media in constructing a Z-type photocatalytic water splitting reaction system, characterized in that perovskite oxysulfide is used as a hydrogen evolution photocatalyst in the Z-type photocatalytic water splitting reaction system;

[0027] The Co-based metal complex redox ion pair is o-phenanthroline cobalt (chemical formula [Co(phen)3]). 3+ / 2+ ) and cobalt bipyridine (chemical formula [Co(bpy)3) 3+ / 2+ At least one of the redox couples;

[0028] The perovskite oxysulfide is at least one of Y2Ti2O5S2 and Sm2Ti2O5S2.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) This invention uses a metal complex [Co(bpy)3] 3+ / 2+ Or [Co(phen)3] 3+ / 2+ As a redox couple, this redox couple is not only easily oxidized by perovskite oxysulfides, but also effectively solves the adsorption and desorption problems on hydrogen evolution and oxygen evolution photocatalysts. This not only enhances the activity of the Z-type photocatalytic water splitting system based on perovskite oxysulfide hydrogen evolution photocatalyst, but also significantly improves its stability.

[0031] (2) The perovskite oxysulfides selected in this invention, such as Y2Ti2O5S2 and Sm2Ti2O5S2, have a wide range of visible light absorption, with absorption wavelengths up to 640nm / 590nm. These materials also exhibit obvious directional charge migration characteristics, which are beneficial to obtaining high photogenerated charge lifetimes. These characteristics enable perovskite oxysulfide materials to make full use of visible light in the solar spectrum, significantly improve the Z-type photocatalytic water splitting activity, and thus achieve more efficient solar energy conversion. Attached Figure Description

[0032] Figure 1 In Example 1, 50 mg of Sm2Ti2O5S2 supported as a co-catalyst was used as the hydrogen evolution photocatalyst, 75 mg of Mo:BiVO4 supported as a co-catalyst was used as the oxygen evolution photocatalyst, and 0.05 mmol [Co(bpy)3] was added. 3+ / 2+ The activity test curve of the Z-type photocatalytic water splitting system, which uses electron transport medium, is shown.

[0033] Figure 2 In Example 1, 50 mg of Y₂Ti₂O₅S₂ supported with a co-catalyst was used as the hydrogen evolution photocatalyst, 75 mg of Mo:BiVO₄ supported with a co-catalyst was used as the oxygen evolution photocatalyst, and 0.05 mmol [Co(bpy)₃] was added. 3+ / 2+ The activity test curve of the Z-type photocatalytic water splitting system, which uses electron transport medium, is shown.

[0034] Figure 3 In Example 2, 50 mg of Y₂Ti₂O₅S₂ supported with a co-catalyst was used as the hydrogen evolution photocatalyst, 75 mg of Mo:BiVO₄ supported with a co-catalyst was used as the oxygen evolution photocatalyst, and 0.05 mmol [Co(phen)₃] was added. 3+ / 2+ The activity test curve of the Z-type photocatalytic water splitting system, which uses electron transport medium, is shown.

[0035] Figure 4 In Example 3, 50 mg of Y₂Ti₂O₅S₂ supported as a co-catalyst was used as the hydrogen evolution photocatalyst, 75 mg of TaON supported as a co-catalyst was used as the oxygen evolution photocatalyst, and 0.05 mmol [Co(bpy)₃] was added. 3+ / 2+ Activity test curves of a Z-type photocatalytic water splitting system with electron transport medium.

[0036] Figure 5 In Example 4, 50 mg of Y₂Ti₂O₅S₂ supported as a co-catalyst was used as the hydrogen evolution photocatalyst, 75 mg of GaN:ZnO supported as a co-catalyst was used as the oxygen evolution photocatalyst, and 0.05 mmol [Co(bpy)₃] was added. 3+ / 2+ Activity test curves of a Z-type photocatalytic water splitting system with electron transport medium.

[0037] Figure 6 In Example 1, 0.05 mmol [Co(bpy)3] was used. 3+ / 2+Using Y2Ti2O5S2 as the electron transport medium, and Mo:BiVO4 as the oxygen evolution photocatalyst, Mo:BiVO4 is used as the oxygen evolution photocatalyst. The activity comparison of Z-type photocatalytic water splitting systems composed of Y2Ti2O5S2 and Mo:BiVO4 in different mass ratios is shown.

[0038] Figure 7 In Example 1, 50 mg of Y₂Ti₂O₅S₂ supported with a co-catalyst was used as the hydrogen evolution photocatalyst, and 75 mg of Mo:BiVO₄ supported with a co-catalyst was used as the oxygen evolution photocatalyst, in 0.05 mmol [Co(bpy)₃] 3+ / 2+ The relationship between the apparent quantum yield of the Z-type photocatalytic water splitting system constructed in this paper and the diffuse reflectance spectra of the hydrogen evolution photocatalyst and the oxygen evolution photocatalyst at different wavelengths is shown in the figure. Detailed Implementation

[0039] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0040] Example 1

[0041] The hydrogen evolution photocatalysts Y₂Ti₂O₅S₂ and Sm₂Ti₂O₅S₂ were prepared by the molten salt method, and the specific steps are as follows:

[0042] Y₂O₃ / Sm₂O₃, TiS₂, TiO₂ (rutile), and MgCl₂ (or other alkali metal / alkaline earth metal chlorides) were mixed and ground for 1 h in a nitrogen-filled glove box at a molar ratio of 1:1.05:0.95:6. To suppress the formation of defects during synthesis, sulfur powder was added to the precursor at 20 mol% of Y₂Ti₂O₅S₂ / Sm₂Ti₂O₅S₂ to create a sulfur atmosphere. The mixture was sealed in a vacuum quartz tube, evacuated to 1.6 Pa, and then calcined at 1173 K for 10 h. After natural cooling, the reaction product was thoroughly ultrasonically washed with 0.01 M NaOH solution to remove molten salt, and then dried in air at 573 K for 3 h. The resulting Y2Ti2O5S2 powder was stirred in 40 mL of 0.5 M H2SO4 solution for 12 h, and then washed with a large amount of water to obtain Y2Ti2O5S2 / Sm2Ti2O5S2 powder.

[0043] The co-catalyst support method is the same for the oxygen sulfide hydrogen evolution photocatalyst (Y2Ti2O5S2 / Sm2Ti2O5S2). Here, we take Y2Ti2O5S2 as an example to illustrate the co-catalyst support method.

[0044] Support of IrO2 as a Y2Ti2O5S2 cocatalyst (microwave hydrothermal method): First, 100 mg of synthesized Y2Ti2O5S2 powder was placed in a glass bottle, and 20 mL of ethylene glycol was added as a solvent. Next, 250 μL of IrCl3 solution (4 mg / mL) was added, and the mixture was heated in a microwave reactor at 423 K for 0.5 h. Subsequently, the product was washed repeatedly with ultrapure water, filtered, dried, and recovered. This yielded IrO2 / Y2Ti2O5S2.

[0045] Support of Au as a cocatalyst in Y2Ti2O5S2 (photodeposition method): 50 μL of HAuCl4 (1 mg / mL) and 50 mg of IrO2 / Y2Ti2O5S2 powder were added to 100 mL of 5 mM Na2S-Na2SO3 aqueous solution. During the photocatalytic reaction, Au particles were loaded onto IrO2 / Y2Ti2O5S2 by irradiation with visible light from a 300W xenon lamp for 1 h. The powder was then washed, filtered, recovered, and dried to obtain Au-IrO2 / Y2Ti2O5S2.

[0046] Rh surface oxide protective layer of Y2Ti2O5S2 2-y Cr y O3 support (photodeposition method): 60 mg Au-IrO2 / Y2Ti2O5S2 powder was dispersed in 100 mL of methanol aqueous solution (50 vol%), followed by the addition of 1.2 mL Na3RhCl6 (1 mg / mL) and 0.45 mL K2CrO4 (4 mg / mL). The photocatalytic reaction was then carried out under full-spectrum irradiation with a 300 W xenon lamp for 4 h. Finally, the product was washed, filtered, recovered, and dried. This yielded Rh... 2-y Cr y O3@Au-IrO2 / Y2Ti2O5S2.

[0047] Preparation of the oxygen evolution photocatalyst Mo:BiVO4: Mo:BiVO4 (Mo:Mo+V=0.04mol%) was synthesized according to the method reported in a previous paper published by our group (Zhang,BY; Xiang,Y.; Guo,M.; Wang,JM; Liu,KW; Lin,WR; Ma,GJ,Fabrication of a Facet-Oriented BiVO4 Photoanode by Particle Engineering for Promotion of Charge Separation Efficiency.[J].ACS Applied Energy Materials2021,4(4),4259-4268.). In this method, Bi(NO3)3·5H2O and NH4VO3 were dissolved in 2.0M HNO3 and 2.0M NaOH solutions, respectively. To introduce Mo doping, a specific amount of NaMoO4 was added to the NaOH solution. The two solutions were then mixed and stirred vigorously until an orange precipitate formed. Subsequently, 10 vol% ethylene glycol was added, and the pH of the resulting mixture was adjusted to 2.0 using an ammonia solution. The suspension was then transferred to a polytetrafluoroethylene-lined stainless steel autoclave and maintained at 473 K for 24 hours. After the reaction, once the autoclave had cooled completely, the resulting crystalline Mo:BiVO4 powder was collected by filtration.

[0048] Oxygen evolution photocatalyst Mo:BiVO4 and oxygen production co-catalyst CoO x Support (photodeposition method): 50 μL of Co(NO3)2 (1 mg / mL) and 50 mg of Mo:BiVO4 powder were added to 100 mL of 10 mM NaIO3 aqueous solution. During the photocatalytic reaction, the CoO2 was irradiated with a 300 W xenon lamp for 4 h to support the photocatalytic reaction. x The particles were loaded onto Mo:BiVO4, and then the powder was washed, filtered, recovered, and dried to obtain CoO. x / Mo:BiVO4.

[0049] Preparation of electron transport medium [Co(bpy)3]SO4: 5 mmol of an aqueous solution of CoSO4·7H2O was mixed with an ethanol solution containing 15 mmol of 2,2′-bipyridine. Acetone or petroleum ether was then added to this mixture to form a [Co(bpy)3]SO4 precipitate, which was then filtered, dried, and baked to obtain [Co(bpy)3]SO4 powder.

[0050] Construction of a Z-type photocatalytic water splitting system: using 50 mg Rh 2-y Cr yO3@Au-IrO2 / Y2Ti2O5S2 or Rh 2- y Cr y O3@Au-IrO2 / Sm2Ti2O5S2 was used as the hydrogen evolution photocatalyst, with 75 mg CoO x / Mo:BiVO4 was used as the oxygen evolution photocatalyst, and both were dispersed in a photocatalytic reactor. First, 100 mL of ultrapure water was added, followed by 0.05 mmol of [Co(bpy)3]SO4 as an electron transport medium to transfer electrons between the oxygen evolution photocatalyst and the hydrogen evolution photocatalyst. Then, a photocatalytic water splitting reaction was carried out under irradiation with a 300 W xenon lamp (λ > 420 nm).

[0051] Figure 1 In Example 1, 50 mg of Sm2Ti2O5S2 supported as a co-catalyst was used as the hydrogen evolution photocatalyst, 75 mg of Mo:BiVO4 supported as a co-catalyst was used as the oxygen evolution photocatalyst, and 0.05 mmol [Co(bpy)3] was added. 3+ / 2+ The activity test curve of the Z-type photocatalytic water splitting system, which uses electron transport medium, is shown.

[0052] Figure 2 In Example 1, 50 mg of Y₂Ti₂O₅S₂ supported with a co-catalyst was used as the hydrogen evolution photocatalyst, 75 mg of Mo:BiVO₄ supported with a co-catalyst was used as the oxygen evolution photocatalyst, and 0.05 mmol [Co(bpy)₃] was added. 3+ / 2+ The activity test curve of the Z-type photocatalytic water splitting system, which uses electron transport medium, is shown.

[0053] Figure 6 In Example 1, 0.05 mmol [Co(bpy)3] was used. 3+ / 2+ Using Y₂Ti₂O₅S₂ as the electron transport medium, and Mo:BiVO₄ as the oxygen evolution photocatalyst, both supported by a co-catalyst, were employed. The activity of Z-type photocatalytic water splitting systems composed of Y₂Ti₂O₅S₂ and Mo:BiVO₄ at different mass ratios was compared. Thanks to its high catalytic efficiency, only 25 mg of the hydrogen evolution photocatalyst and 50 mg of the oxygen evolution photocatalyst were needed to achieve a high level of photocatalytic water splitting activity. Further optimization of the mass ratio of the hydrogen evolution and oxygen evolution photocatalysts revealed that when the hydrogen evolution photocatalyst was 50 mg and the oxygen evolution photocatalyst was 75 mg, the highest H₂ and O₂ emission rates from the photocatalytic water splitting reached 141 / 70.5 μmol h⁻¹. –1 This is the highest value obtained to date for a Z-type total water splitting system constructed using oxysulfides as a hydrogen evolution photocatalyst.

[0054] Figure 7 In Example 1, 50 mg of Y₂Ti₂O₅S₂ supported with a co-catalyst was used as the hydrogen evolution photocatalyst, and 75 mg of Mo:BiVO₄ supported with a co-catalyst was used as the oxygen evolution photocatalyst, in 0.05 mmol of [Co(bpy)₃]. 3+ / 2+ The apparent quantum yield (AQY) of the Z-type total water splitting reaction (100 mL water reaction system) constructed in this study is related to the diffuse reflectance spectra of the hydrogen evolution photocatalyst and the oxygen evolution photocatalyst at different incident light wavelengths. In this reaction system, the AQY at 420 nm is 4.14%, which is the highest value obtained to date for Z-type total water splitting constructed using oxysulfides as hydrogen evolution photocatalysts.

[0055] Example 2

[0056] In this embodiment, the preparation methods of the hydrogen evolution photocatalyst Y2Ti2O5S2 and the oxygen evolution photocatalyst Mo:BiVO4, as well as the co-catalyst support methods, are the same as in Example 1.

[0057] Preparation of the electron transport medium [Co(phen)3]SO4: 5 mmol of an aqueous solution of CoSO4·7H2O was mixed with an ethanol solution containing 15 mmol of 1,10-phenanthroline. Acetone or petroleum ether was then added to this mixture to form a [Co(phen)3]SO4 precipitate, which was then filtered and dried to obtain [Co(phen)3]SO4 powder.

[0058] Construction of a Z-type photocatalytic water splitting system: using 50 mg Rh 2-y Cr y O3@Au-IrO2 / Y2Ti2O5S2 was used as the hydrogen evolution photocatalyst, with 75 mg CoO x / Mo:BiVO4 was used as the oxygen evolution photocatalyst, and both were dispersed in a photocatalytic reactor. First, 100 mL of ultrapure water was added, followed by 0.05 mmol of [Co(phen)3]SO4 as an electron transport medium to transfer electrons between the oxygen evolution photocatalyst and the hydrogen evolution photocatalyst. Then, a photocatalytic water splitting reaction was carried out under irradiation with a 300 W xenon lamp (λ > 420 nm).

[0059] Figure 3 In Example 2, 50 mg of Y₂Ti₂O₅S₂ supported with a co-catalyst was used as the hydrogen evolution photocatalyst, 75 mg of Mo:BiVO₄ supported with a co-catalyst was used as the oxygen evolution photocatalyst, and 0.05 mmol [Co(phen)₃] was added. 3+ / 2+ The activity test curve of the Z-type photocatalytic water splitting system, which uses electron transport medium, is shown.

[0060] Example 3

[0061] In this embodiment, the preparation method of the hydrogen evolution photocatalyst Y2Ti2O5S2 and the co-catalyst support method are the same as in Example 1.

[0062] Preparation of TaON: Ta powder, KTaO3, and KCl were ground and mixed in different atomic ratios. The precursor and NH4Cl were vacuum-sealed in a quartz tube according to the precursor ratio. The quartz tube was transferred to a muffle furnace and heated at 703 K for 2 hours, followed by a further heating at a higher temperature for 2 hours. The quartz tube was then allowed to cool naturally to room temperature. The resulting powder was washed with water and dried at 323 K for 2 hours.

[0063] Supporting TaON oxygen-generating co-catalyst IrO2 (microwave hydrothermal method): First, 100 mg of synthesized TaON powder was placed in a glass bottle, and 20 mL of ethylene glycol was added as a solvent. Next, 125 μL of IrCl3 solution (4 mg / mL) was added, and the mixture was heated in a microwave reactor at 423 K for 0.5 h. Subsequently, the product was washed repeatedly with ultrapure water, filtered, dried, and recovered. This yielded IrO2 / TaON.

[0064] Support of Au as a co-catalyst for hydrogen production in TaON (photodeposition method): 50 μL of HAuCl4 (Au 1 mg / mL) and 50 mg of IrO2 / TaON powder were added to 100 mL of 20 vol% methanol aqueous solution. During the photocatalytic reaction, Au particles were loaded onto Au-IrO2 / TaON by irradiation with visible light from a 300 W xenon lamp for 1 h. The powder was then washed, filtered, recovered, and dried to obtain Au-IrO2 / TaON.

[0065] Preparation of the electron transport medium [Co(bpy)3]SO4: 5 mmol of an aqueous solution of CoSO4·7H2O was mixed with an ethanol solution containing 15 mmol of 2,2′-bipyridine. Acetone or petroleum ether was then added to this mixture to form a [Co(bpy)3]SO4 precipitate, which was then filtered and dried to obtain [Co(bpy)3]SO4 powder.

[0066] Construction of a Z-type photocatalytic water splitting system: using 50 mg Rh 2-y Cr yO3@Au-IrO2 / Y2Ti2O5S2 was used as the hydrogen evolution photocatalyst, and 75 mg Au-IrO2 / TaON was used as the oxygen evolution photocatalyst. Both were dispersed in a photocatalytic reactor. First, 100 mL of ultrapure water was added, followed by 0.05 mmol of [Co(bpy)3]SO4 as an electron transport medium to transfer electrons between the oxygen and hydrogen evolution photocatalysts. Then, a photocatalytic water splitting reaction was carried out under irradiation with a 300 W xenon lamp (λ > 420 nm).

[0067] Figure 4 In Example 3, 50 mg of Y₂Ti₂O₅S₂ supported as a co-catalyst was used as the hydrogen evolution photocatalyst, 75 mg of TaON supported as a co-catalyst was used as the oxygen evolution photocatalyst, and 0.05 mmol [Co(bpy)₃] was added. 3+ / 2+ Activity test curves of a Z-type photocatalytic water splitting system with electron transport medium.

[0068] Example 4

[0069] In this embodiment, the preparation method of the hydrogen evolution photocatalyst Y2Ti2O5S2 and the co-catalyst support method are the same as in Example 1.

[0070] Preparation of GaN:ZnO: Ga2O3 and Zn powder were mixed in an agate mortar with a Zn / Ga molar ratio of 3.5:1. Subsequently, 150 mg of the resulting mixture and 30 mg of NH4Cl were sealed in a vacuum quartz tube and calcined in a muffle furnace at 703 K for 2 h, during which NH4Cl decomposed into NH3 and HCl. The calcination was carried out at 2.5 K min. -1 The reaction rate was further increased to 1073 K and held for 6 h, followed by natural cooling. To remove residual Zn, the reacted powder was washed by soaking in 1.5 M HNO3 for 2 h, then filtered and dried in air. Finally, the resulting powder was annealed at 873 K for 1 h to eliminate defects in the GaN:ZnO particles.

[0071] Supporting IrO2 as an oxygen-generating co-catalyst in GaN:ZnO (microwave hydrothermal method): First, 100 mg of synthesized GaN:ZnO powder was placed in a glass bottle, and 20 mL of ethylene glycol was added as a solvent. Next, 125 μL of IrCl3 solution (4 mg / mL) was added, and the mixture was heated in a microwave reactor at 423 K for 0.5 h. Subsequently, the product was washed multiple times with ultrapure water, filtered, dried, and recovered. This yielded IrO2 / GaN:ZnO.

[0072] Preparation of the electron transport medium [Co(bpy)3]SO4: 5 mmol of an aqueous solution of CoSO4·7H2O was mixed with an ethanol solution containing 15 mmol of 2,2′-bipyridine. Acetone or petroleum ether was then added to this mixture to form a [Co(bpy)3]SO4 precipitate, which was then filtered and dried to obtain [Co(bpy)3]SO4 powder.

[0073] Construction of a Z-type photocatalytic water splitting system: using 50 mg Rh 2-y Cr y O3@Au-IrO2 / Y2Ti2O5S2 was used as the hydrogen evolution photocatalyst, and 75 mg of IrO2 / GaN:ZnO was used as the oxygen evolution photocatalyst. Both were dispersed in a photocatalytic reactor. First, 100 mL of ultrapure water was added, followed by 0.05 mmol of [Co(bpy)3]SO4 as an electron transport medium to transfer electrons between the oxygen and hydrogen evolution photocatalysts. Then, a photocatalytic water splitting reaction was carried out under irradiation with a 300 W xenon lamp (λ > 420 nm).

[0074] Figure 5 In Example 4, 50 mg of Y₂Ti₂O₅S₂ supported with a co-catalyst was used as the hydrogen evolution photocatalyst, 75 mg of GaN:ZnO supported with a co-catalyst was used as the oxygen evolution photocatalyst, and 0.05 mmol [Co(bpy)₃] was added. 3+ / 2+ Activity test curves of a Z-type photocatalytic water splitting system with electron transport medium.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make several improvements and additions without departing from the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A method for constructing a Z-type photocatalytic water splitting reaction system based on perovskite oxysulfide, characterized by, Includes the following steps: Step 1): Prepare perovskite oxysulfide semiconductor particles and support them with the co-catalyst Au-IrO2, then prepare a surface oxide protective layer Rh. 2-y Cr y O3 was used as a hydrogen evolution photocatalyst in the Z-type photocatalytic water splitting reaction system. Step 2): Prepare at least one of the following catalysts with photocatalytic oxygen production activity: Mo:BiVO4, TaON and GaN:ZnO and support the corresponding co-catalyst, so as to serve as the oxygen evolution photocatalyst in the Z-type photocatalytic water splitting reaction system. Step 3): Add the hydrogen evolution photocatalyst obtained in Step 1 and the oxygen evolution photocatalyst obtained in Step 2 to water, and add Co-based metal complex redox ion pairs as electron transport media to complete the construction of the Z-type photocatalytic water splitting reaction system. The perovskite oxysulfide semiconductor particles in step 1) are at least one of Y2Ti2O5S2 and Sm2Ti2O5S2. The Co-based metal complex oxidation / reduction ion pair in the step 3) is at least one of [Co(phen)3] 3+ / 2+ and [Co(bpy)3] 3+ / 2+ .

2. The construction method of claim 1, wherein, The perovskite oxysulfide semiconductor particles in step 1) are prepared by solid-phase synthesis or hydrogen sulfide sulfidation.

3. The construction method of claim 2, wherein, In step 1), the perovskite oxysulfide semiconductor particles are prepared by molten salt-assisted solid-state method. The specific preparation process includes: mixing and grinding Y2O3 or Sm2O3, TiS2, TiO2 and molten salt in an inert gas atmosphere at a molar ratio of 1:1.05:0.95:6, then adding sulfur powder, evacuating the vacuum, and calcining; after natural cooling, washing to remove the molten salt and drying to obtain the final product.

4. The construction method of claim 1, wherein, The cocatalyst in step 2) is a metal oxide and / or a noble metal cocatalyst, wherein the metal oxide cocatalyst is selected from at least one of RuO2, IrO2, oxides of manganese, oxides of cobalt and oxides of nickel.

5. The construction method of claim 1 wherein, The hydrogen evolution photocatalyst in step 1) is Rh 2- y Cr y O3@Au-IrO2 / Y2Ti2O5S2 and Rh 2-y Cr y At least one of O3@Au-IrO2 / Sm2Ti2O5S2; and / or the oxygen evolution photocatalyst in step 2) is CoO x / Mo: BiVO4, Au-IrO2 / TaON, and IrO2 / GaN:ZnO.

6. The construction method of claim 5, wherein, In the Z-type photocatalytic water splitting reaction system constructed in step 4), the concentrations of the hydrogen evolution photocatalyst and the oxygen evolution photocatalyst are 0.25~5 g / L; their concentration ratio is 1:0.5~4; and the concentration of the Co-based metal complex redox ion pair is 0.01~1 mmol / L.

7. A catalyst composition characterized in that, This includes hydrogen evolution photocatalysts, oxygen evolution photocatalysts, and Co-based metal complex redox ion pairs; The hydrogen evolution photocatalyst is Rh 2-y Cr y O3@Au-IrO2 / Y2Ti2O5S2 and Rh 2-y Cr y At least one of O3@Au-IrO2 / Sm2Ti2O5S2; the oxygen evolution photocatalyst is CoO x / Mo: BiVO4, Au-IrO2 / TaON, and IrO2 / GaN:ZnO. The Co-based metal complex has a redox ion pair of [Co(phen)3]. 3+ / 2+ and [Co(bpy)3] 3+ / 2+ At least one of them.

8. The application of the catalyst composition according to claim 7 in the photocatalytic water splitting reaction.

9. Use of a Co-based metal complex redox ion pair as an electron transport medium in the construction of a Z-type photocatalytic water splitting reaction system, characterized in that, In the Z-type photocatalytic water splitting reaction system, Au-IrO2 is supported by perovskite oxysulfide semiconductor particles, and then a surface oxide protective layer Rh2-yCryO3 is prepared as a hydrogen evolution photocatalyst. The Co-based metal complex oxidation / reduction ion pair is at least one of [Co(phen)3] 3+ / 2+ and [Co(bpy)3] 3+ / 2+ . The perovskite oxysulfide is at least one of Y2Ti2O5S2 and Sm2Ti2O5S2.

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