A Ru, O co-doped ZnIn2S4 photocatalyst, its preparation method and application, and a method for photocatalytic water splitting to produce hydrogen.

Abstract

The application relates to the technical field of photocatalytic materials, in particular to a Ru and O co-doped ZnIn2S4 photocatalyst, a preparation method and application thereof, and a method for photocatalytic water decomposition to produce hydrogen. The Ru and O co-doped ZnIn2S4 photocatalyst takes hexagonal phase ZnIn2S4 as a matrix, Ru element is doped to replace the position of In in the ZnIn2S4 crystal lattice, and O element is doped to replace the position of S in the ZnIn2S4 crystal lattice. The Ru and O co-doped ZnIn2S4 photocatalyst realizes double-element synergistic modification by Ru replacing the In crystal lattice position and O replacing the S crystal lattice position, Ru plays a high-efficiency charge trap effect to inhibit the recombination of electron-hole pairs, O narrows the band gap width, the light absorption edge is red shifted to 570 nm, the spectral response range is widened, and the energy band structure and surface active sites are synergistically optimized. The photocatalytic hydrogen production rate is up to 1.7234 mmol.g ‑1 ·h ‑1 -1.h-1, 86.95% of the initial performance is still retained after 4 cycles, the photocatalyst has high activity and excellent stability, and can be efficiently applied to photocatalytic water decomposition to produce hydrogen driven by visible light.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, and in particular to a Ru, O co-doped ZnIn2S4 photocatalyst, its preparation method and application, and a method for photocatalytic water splitting to produce hydrogen. Background Technology

[0002] Hydrogen energy, as an ideal clean energy source, boasts significant advantages such as high calorific value, pollution-free combustion products, and abundant reserves, making it one of the most promising energy carriers for future energy systems. However, current mainstream industrial hydrogen production methods, such as steam methane reforming and coal gasification, rely on fossil fuels, inevitably generating large amounts of greenhouse gases like carbon dioxide during the process. Therefore, developing green and low-carbon hydrogen production technologies is urgently needed. Photocatalytic water splitting technology can directly utilize inexhaustible solar energy to decompose water into hydrogen and oxygen. It offers advantages such as mild reaction conditions, no secondary pollution, and a wide range of raw material sources, making it a crucial pathway for the efficient conversion of solar energy into hydrogen energy, with enormous development potential and application prospects.

[0003] The efficiency of photocatalytic reactions hinges on the performance of the photocatalyst, whose activity is primarily determined by three key factors: the catalyst's absorption capacity for visible light, the separation and transport efficiency of photogenerated electron-hole pairs, and the rate of photoinduced electron transfer to active sites on the catalyst surface. Although researchers have developed various types of photocatalytic materials, most traditional photocatalysts suffer from narrow visible light response ranges, severe recombination of photogenerated carriers, and poor stability, significantly hindering the industrial application of photocatalytic hydrogen production technology.

[0004] Zinc indium sulfide (ZnIn2S4, or ZIS for short) is a typical ternary metal sulfide semiconductor photocatalyst. Due to its environmental friendliness, excellent chemical stability, tunable band gap (2.06–2.85 eV), and band position matching requirements for photocatalytic hydrogen evolution reactions, it has attracted widespread attention in the field of photocatalytic hydrogen production in recent years. However, pure ZIS materials suffer from rapid photogenerated carrier recombination rates and low charge separation efficiency, which limit its photocatalytic activity and stability.

[0005] To address these issues, researchers have proposed various modification strategies, including controlling material morphology, constructing heterojunctions, elemental doping, and defect engineering. Among these, elemental doping is a simple, practical, and precise method for controlling the electronic structure of semiconductors. By introducing foreign atoms into the material lattice to replace existing atoms, the band structure, light absorption performance, and surface reactivity of the catalyst can be effectively adjusted. Existing research shows that single-element doping modification strategies still have insurmountable limitations. While single metal doping can effectively suppress carrier recombination, its ability to control the light absorption range of the catalyst is limited. While single non-metal doping can broaden the spectral response range, it is prone to severe carrier recombination due to excessively high carrier concentrations, which in turn restricts further improvement in photocatalytic performance.

[0006] Therefore, developing a ZnIn2S4-based photocatalyst that combines broad spectral response, high charge separation efficiency, and excellent stability is of great significance for promoting the development of photocatalytic hydrogen production technology. Summary of the Invention

[0007] The purpose of this invention is to overcome the inherent defects of pure ZnIn2S4, such as high photogenerated carrier recombination rate, low charge separation efficiency, and the limited light absorption regulation capability of metal doping and the tendency of non-metal doping to induce excessive carrier recombination. This invention provides a Ru / O co-doped ZnIn2S4 photocatalyst, its preparation method, and its application, as well as a method for photocatalytic water splitting to produce hydrogen. This Ru / O co-doped ZnIn2S4 photocatalyst achieves synergistic modification through Ru substituting In lattice sites and O substituting S lattice sites. Ru exerts a highly efficient charge trapping effect, suppressing electron-hole pair recombination; O narrows the band gap, redshifting the light absorption edge to 570 nm and broadening the spectral response range. The two elements synergistically optimize the band structure and surface active sites. Furthermore, the preparation method of this Ru / O co-doped ZnIn2S4 photocatalyst is a one-step hydrothermal method, which is simple, mild, and cost-effective. Moreover, the photocatalytic hydrogen production rate of this Ru / O co-doped ZnIn2S4 photocatalyst reaches a maximum of 1.7234 mmol·g⁻¹. -1 ·h -1 It retains 86.95% of its initial performance after 4 cycles, combining high activity with excellent stability, and can be efficiently applied to visible light-driven photocatalytic water splitting for hydrogen production.

[0008] To achieve the above objectives, in a first aspect, the present invention provides a Ru-O co-doped ZnIn2S4 photocatalyst, wherein the Ru-O co-doped ZnIn2S4 photocatalyst uses hexagonal ZnIn2S4 as a matrix, with Ru doping replacing the In sites in the ZnIn2S4 lattice and O doping replacing the S sites in the ZnIn2S4 lattice.

[0009] Preferably, the mass fraction of Ru in the Ru, O co-doped ZnIn2S4 photocatalyst is 3-5 wt%.

[0010] Preferably, the Ru and O co-doped ZnIn2S4 photocatalyst has a micro-flower-like hierarchical structure assembled from two-dimensional nanosheets.

[0011] Preferably, the size of the micro-flower-like hierarchical structure is 300~1000nm.

[0012] Preferably, the width of the two-dimensional nanosheet is 18~47nm.

[0013] Secondly, the present invention provides a method for preparing Ru, O co-doped ZnIn2S4 photocatalyst as described in the present invention. The preparation method includes: in the presence of a solvent, first adding zinc salt, indium salt and sulfur source to the solvent to dissolve, then adding oxygen source and ruthenium salt to mix, carrying out a hydrothermal reaction, cooling, washing, and drying to obtain Ru, O co-doped ZnIn2S4 photocatalyst.

[0014] Preferably, the solvent is water.

[0015] Preferably, the zinc salt is selected from one or more of zinc chloride, zinc acetate, and zinc acetate.

[0016] Preferably, the indium salt is indium trichloride tetrahydrate and / or indium nitrate.

[0017] Preferably, the sulfur source is selected from one or more of thioacetamide, thiourea, and L-cysteine.

[0018] Preferably, the oxygen source is selected from one or more of polyvinylpyrrolidone, ethylene glycol, and citric acid.

[0019] Preferably, the ruthenium salt is selected from one or more of ruthenium trichloride hydrate, ruthenium acetate, and ruthenium acetylacetonate.

[0020] Preferably, the molar ratio of the zinc salt, indium salt, sulfur source, oxygen source and ruthenium salt is 1:1.8~2.2:7~9:0.002~0.005:0.15~0.22.

[0021] Preferably, the dissolution conditions include: a temperature of 15~30℃, a time of 20~40min, and a stirring rate of 300~500rpm.

[0022] Preferably, the mixing conditions include: a temperature of 15~30℃, a time of 15~30min, and a stirring rate of 300~500rpm.

[0023] Preferably, the conditions for the hydrothermal reaction include: a heating rate of 3~8℃ / min, a final reaction temperature of 160~200℃, and a constant temperature holding time of 12~24h.

[0024] Preferably, the cooling is to 15~30°C.

[0025] Preferably, the washing conditions include washing with deionized water and anhydrous ethanol 3 to 5 times each, and the washing method is to alternate between deionized water and anhydrous ethanol.

[0026] Preferably, the drying conditions include: vacuum conditions, a temperature of 60~100℃, and a time of 8~16h.

[0027] Thirdly, the present invention provides an application of the Ru, O co-doped ZnIn2S4 photocatalyst as described in the present invention in photocatalytic water splitting for hydrogen production.

[0028] Fourthly, the present invention provides a method for photocatalytic water splitting to produce hydrogen, the method comprising: 1) Disperse the photocatalyst in an aqueous sacrificial agent solution and add an alkaline regulator to obtain the reaction solution; 2) Under an inert atmosphere, the reaction solution obtained in step 1) is subjected to photocatalytic hydrogen evolution reaction under visible light irradiation; In step 1), the photocatalyst is the Ru, O co-doped ZnIn2S4 photocatalyst described in this invention.

[0029] Preferably, in step 1), the sacrificial agent is selected from one or more of triethanolamine, methanol, lactic acid, and sodium sulfide / sodium sulfite compound reagent.

[0030] Preferably, in step 1), the volume fraction of the sacrificial agent aqueous solution is 15-25%.

[0031] Preferably, in step 1), the ratio of the photocatalyst to the sacrificial agent aqueous solution is 80~120 mg:20 mL.

[0032] Preferably, in step 1), the alkali adjuster is sodium hydroxide and / or potassium hydroxide.

[0033] Preferably, in step 1), the ratio of the amount of alkali adjuster to the sacrificial agent aqueous solution is 1.2~1.8g:20mL.

[0034] Preferably, in step 2), the inert atmosphere is a nitrogen atmosphere and / or an argon atmosphere.

[0035] Preferably, in step 2), the wavelength range of the visible light is λ>420 nm.

[0036] Preferably, in step 2), the temperature of the photocatalytic hydrogen evolution reaction is 15~30℃.

[0037] In the above technical solution, the Ru and O co-doped ZnIn2S4 photocatalyst of the present invention, through the synergistic effect of Ru and O dual-element lattice doping, simultaneously solves the inherent defects of pure ZnIn2S4, such as rapid recombination of photogenerated carriers, low charge separation efficiency, and insufficient light absorption regulation or excessive carrier recombination, as well as the defects of single-element doping. Ru replaces the In sites in the ZnIn2S4 lattice, exerting a highly efficient charge trapping effect, rapidly capturing photogenerated electrons and constructing directional electron transfer channels, significantly suppressing electron-hole recombination. O replaces the S sites, narrowing the band gap through hybridization with the ZnIn2S4 valence band orbitals, redshifting the light absorption edge to 570 nm, extending the light response range from the visible light region to the near-infrared region, and significantly improving solar energy utilization. Dual-element doping does not destroy the micro-flower-like hierarchical structure of the material, while increasing the surface hydroxyl content, providing abundant active sites for the photocatalytic reaction, which is beneficial to the adsorption and protonation processes of reactants. The optimal sample obtained achieved a photocatalytic hydrogen production rate of up to 1.7234 mmol·g. -1 ·h -1 It achieves an apparent quantum efficiency of 12.88% at a wavelength of 400 nm and retains 86.95% of its initial activity after four cycles of reaction. It combines high catalytic activity with excellent resistance to photocorrosion, which is far superior to pure ZnIn2S4 and single O-doped samples.

[0038] Meanwhile, the Ru and O co-doped ZnIn2S4 photocatalyst of the present invention is prepared by a one-step hydrothermal method, which is simple, the raw materials are readily available, the reaction conditions are mild, no complicated post-processing is required, and it is easy to achieve large-scale production. It has broad application prospects in the field of visible light-driven photocatalytic water splitting for hydrogen production.

[0039] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0040] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1Images (a)-(b) are scanning electron microscope (SEM) images and magnified SEM images of the ZnIn2S4 photocatalyst prepared in Comparative Example 1 of the present invention; images (c)-(d) are SEM images and magnified SEM images of the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 of the present invention; images (e)-(f) are SEM images and magnified SEM images of the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of the present invention; image (g) is a transmission electron microscope (TEM) image of the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of the present invention; image (h) is a high-resolution transmission electron microscope (HRTEM) image of the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of the present invention; and image (i) is an EDS image of the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of the present invention. Figure 2 X-ray diffraction (XRD) patterns of the Ru and O co-doped ZnIn2S4 photocatalysts prepared in Examples 1-6 of this invention, the ZnIn2S4 photocatalyst prepared in Comparative Example 1, and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2. Figure 3 Fourier transform infrared (FT-IR) spectra of the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of the present invention, the ZnIn2S4 photocatalyst prepared in Comparative Example 1, and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2. Figure 4 The UV-Vis DRS spectra of the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of the present invention, the ZnIn2S4 photocatalyst prepared in Comparative Example 1, and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 are shown. Figure 5 The photoluminescence (PL) spectra of the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of the present invention, the ZnIn2S4 photocatalyst prepared in Comparative Example 1, and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 are shown. Figure 6 The photocurrent response spectra of the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of the present invention, the ZnIn2S4 photocatalyst prepared in Comparative Example 1, and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 are shown. Figure 7(a) shows the hydrogen production rate of the Ru and O co-doped ZnIn2S4 photocatalysts prepared in Examples 1-6 of the present invention and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 over time; (b) shows the hydrogen production rate of the Ru and O co-doped ZnIn2S4 photocatalysts prepared in Examples 1-6 of the present invention and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2; (c) shows the cycle performance of photocatalytic hydrogen production of the Ru and O co-doped ZnIn2S4 photocatalysts prepared in Example 4 of the present invention, the ZnIn2S4 photocatalysts prepared in Comparative Example 1 and the O-doped ZnIn2S4 photocatalysts prepared in Comparative Example 2; (d) shows the apparent quantum efficiency of the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of the present invention. Figure 8 This is a diagram illustrating the photocatalytic hydrogen production mechanism of the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of this invention. Detailed Implementation

[0041] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0042] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0043] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0044] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0045] In a first aspect, the present invention provides a Ru-O co-doped ZnIn2S4 photocatalyst, wherein the Ru-O co-doped ZnIn2S4 photocatalyst is based on hexagonal ZnIn2S4, with Ru doping replacing the In sites in the ZnIn2S4 lattice and O doping replacing the S sites in the ZnIn2S4 lattice.

[0046] Among various metal doping candidate elements, ruthenium (Ru) stands out as an important industrial metal photocatalyst with a cost advantage among platinum group elements. Compared to Pt, Ru exhibits superior catalytic performance in the hydrogen evolution reaction due to its narrower Ru-H band gap, enabling highly efficient H+ ionization. + Activation and Adsorption Capabilities. Introducing Ru into the ZIS lattice for doping modification allows for the tuning of band structure and energy level potentials, optimization of local electronic configuration, and enhancement of the material's visible light absorption. In non-metallic doped systems, oxygen (O)-doped ultrathin ZIS nanosheets exhibit excellent catalytic activity in the photocatalytic hydrogen evolution reaction. The core reason is that O doping effectively promotes the separation rate of photogenerated electron-hole pairs. Simultaneously, O doping also improves the material's resistance to photocorrosion; however, excessively high carrier concentrations can easily induce severe carrier recombination, preventing complete water splitting in O-doped ZIS.

[0047] The Ru and O co-doped ZnIn2S4 photocatalyst of this invention combines high catalytic activity with structural stability. It fully leverages the efficient charge trapping effect of Ru doping to effectively capture photogenerated carriers and significantly suppress electron-hole recombination. Simultaneously, relying on the unique advantages of O doping in band structure modulation and lattice structure optimization, it achieves band structure optimization and effective broadening of the photoresponse range. The synergistic effect of Ru and O doping can significantly improve the photocatalytic hydrogen production performance of ZIS.

[0048] In this invention, the mass fraction of Ru in the Ru, O co-doped ZnIn2S4 photocatalyst is 3-5 wt%.

[0049] In this invention, the Ru and O co-doped ZnIn2S4 photocatalyst is a micro-flower-like hierarchical structure assembled from two-dimensional nanosheets.

[0050] In this invention, the size of the micro-flower-like hierarchical structure is 300~1000nm.

[0051] In this invention, the width of the two-dimensional nanosheet is 18~47nm.

[0052] Secondly, the present invention provides a method for preparing Ru, O co-doped ZnIn2S4 photocatalyst as described in the present invention. The preparation method includes: in the presence of a solvent, first adding zinc salt, indium salt and sulfur source to the solvent to dissolve, then adding oxygen source and ruthenium salt to mix, carrying out a hydrothermal reaction, cooling, washing, and drying to obtain Ru, O co-doped ZnIn2S4 photocatalyst.

[0053] The Ru and O co-doped ZnIn2S4 photocatalyst of this invention employs a one-step hydrothermal method to simultaneously complete ZnIn2S4 crystal growth and Ru and O dual-element doping, effectively avoiding defects such as local element agglomeration and lattice integrity damage that are prone to occur in stepwise doping processes, and ensuring uniform distribution of the two elements in the micro-flower hierarchical structure. The raw materials used are all commonly used and inexpensive industrial reagents, eliminating the need for complex precious metal precursors, thus keeping costs under control. The reaction conditions are mild, eliminating the need for high-energy-consuming steps such as high-temperature calcination, and the post-processing only requires centrifugal washing and vacuum drying. The process is simple, reproducible, and easy to scale up, providing feasible technical support for the practical application of this photocatalyst in the field of visible light-driven photocatalytic water splitting for hydrogen production.

[0054] In this invention, the solvent is selected from commonly used polar solvents in the art, which can fully dissolve the reactants and provide a reaction environment. The solvent is water, for example, it can be selected from one or more of distilled water, ultrapure water and deionized water.

[0055] In this invention, the zinc salt is a soluble divalent zinc salt, such as one or more selected from zinc chloride, zinc acetate, and zinc acetate.

[0056] In this invention, the indium salt is a soluble trivalent indium salt, such as indium trichloride tetrahydrate and / or indium nitrate.

[0057] In this invention, the sulfur source can slowly decompose and release sulfur under hydrothermal conditions. 2- To avoid grain agglomeration caused by rapid precipitation, it is beneficial to form a ZnIn2S4 microflower structure with high crystallinity and uniform morphology, for example, one or more selected from thioacetamide, thiourea and L-cysteine.

[0058] In this invention, the oxygen source is selected from one or more of polyvinylpyrrolidone, ethylene glycol and citric acid. PVP can not only be used as an oxygen source to realize O substitution doping at S sites, but also as a surfactant to regulate the crystal growth direction, inhibit nanosheet aggregation, and assist in the construction of a three-dimensional micro-flower-like hierarchical structure.

[0059] In this invention, the ruthenium salt is selected from ruthenium salts with good water solubility, such as one or more of ruthenium trichloride hydrate, ruthenium acetate, and ruthenium acetylacetonate.

[0060] In this invention, the molar ratio of zinc salt, indium salt, sulfur source, oxygen source and ruthenium salt is 1:1.8~2.2:7~9:0.002~0.005:0.15~0.22. Within this range, the Ru and O co-doped ZnIn2S4 photocatalyst is free of impurities and has good photocatalytic performance.

[0061] In this invention, the dissolution conditions include: a temperature of 15~30℃, a time of 20~40min, and a stirring rate of 300~500rpm; the mixing conditions include: a temperature of 15~30℃, a time of 15~30min, and a stirring rate of 300~500rpm; stepwise addition ensures uniform dispersion of the oxygen source and ruthenium salt, prevents element agglomeration caused by excessively high local concentrations, and ensures uniformity of dual-element doping.

[0062] In this invention, the conditions for the hydrothermal reaction include: a heating rate of 3~8℃ / min, where a heating rate that is too slow leads to excessive grain growth, while a heating rate that is too fast leads to low crystallinity and too many defects; a final reaction temperature of 160~200℃, where ZnIn2S4 crystallizes incompletely below 160℃, and the micro-flower structure is prone to collapse above 200℃; and a constant temperature holding time of 12~24h, where a reaction time that is too short results in insufficient crystallinity, while a reaction time that is too long leads to nanosheet aggregation and a decrease in specific surface area.

[0063] In this invention, the temperature is cooled to 15~30℃.

[0064] In this invention, the washing conditions include washing with deionized water and anhydrous ethanol 3 to 5 times each, and the washing method is to alternate between deionized water and anhydrous ethanol.

[0065] In this invention, the drying conditions include: vacuum conditions, a temperature of 60~100℃, and a time of 8~16h.

[0066] Thirdly, the present invention provides an application of the Ru, O co-doped ZnIn2S4 photocatalyst as described in the present invention in photocatalytic water splitting for hydrogen production.

[0067] Fourthly, the present invention provides a method for photocatalytic water splitting to produce hydrogen, the method comprising: 1) Disperse the photocatalyst in an aqueous sacrificial agent solution and add an alkaline regulator to obtain the reaction solution; 2) Under an inert atmosphere, the reaction solution obtained in step 1) is subjected to photocatalytic hydrogen evolution reaction under visible light irradiation; In step 1), the photocatalyst is the Ru, O co-doped ZnIn2S4 photocatalyst described in this invention.

[0068] In step 1) of this invention, the sacrificial agent is a commonly used hole sacrificial agent that can quickly capture photogenerated holes and suppress carrier recombination. For example, it can be selected from one or more of triethanolamine, methanol, lactic acid and sodium sulfide / sodium sulfite compound reagents.

[0069] In step 1) of this invention, the volume fraction of the sacrificial agent aqueous solution is 15-25%.

[0070] In step 1) of this invention, the ratio of the amount of photocatalyst to the sacrificial agent aqueous solution is 80~120 mg:20 mL.

[0071] In step 1) of this invention, the alkali adjuster is one or more of sodium hydroxide and / or potassium hydroxide.

[0072] In step 1) of this invention, the ratio of the amount of the alkali regulator to the sacrificial agent aqueous solution is 1.2~1.8g:20mL.

[0073] In step 2) of this invention, the inert atmosphere is a nitrogen atmosphere and / or an argon atmosphere.

[0074] In step 2) of the present invention, the wavelength range of the visible light is λ>420 nm.

[0075] In step 2) of this invention, the temperature of the photocatalytic hydrogen evolution reaction is 15~30℃.

[0076] In this invention, the room temperature is 15~30℃.

[0077] The present invention will be described in detail below through examples, but the scope of protection of the present invention is not limited thereto. In the following examples, the drugs and pharmaceuticals are all conventional commercially available products.

[0078] Example 1 (1) Weigh 1 mmol zinc chloride, 2 mmol indium trichloride tetrahydrate and 8 mmol thioacetamide, add them to 40 mL deionized water, and stir continuously at room temperature for 30 min until the solid is completely dissolved; then add 0.003 mmol polyvinylpyrrolidone (PVP) and 0.15 mmol ruthenium trichloride hydrate (RuCl3·xH2O), and continue stirring for 20 min until the mixture is uniform; transfer to a 100 mL hydrothermal reactor, seal it and place it in an oven, heat it to 180 °C at a rate of 5 °C / min, and keep it at a constant temperature for 18 h. After the reaction is completed, cool it naturally to room temperature (15~30 °C) to obtain a yellow precipitate.

[0079] (2) The yellow precipitate obtained in step (1) was washed three times each by centrifugation with deionized water and anhydrous ethanol. Then the product was placed in a vacuum drying oven and dried at 80°C for 12 hours to obtain a Ru and O co-doped ZnIn2S4 photocatalyst, denoted as (Ru,O)-ZIS1, in which the mass fraction of Ru element was 3.46wt%.

[0080] Example 2 The method of Example 1 was carried out, except that “0.15 mmol ruthenium trichloride hydrate” in step (1) was replaced with “0.18 mmol ruthenium trichloride hydrate”, and other conditions remained unchanged, to obtain a Ru and O co-doped ZnIn2S4 photocatalyst, denoted as (Ru,O)-ZIS2, wherein the mass fraction of Ru element was 4.12 wt%.

[0081] Example 3 The method of Example 1 was carried out, except that “0.15 mmol ruthenium trichloride hydrate” in step (1) was replaced with “0.19 mmol ruthenium trichloride hydrate”, and other conditions remained unchanged, to obtain a Ru and O co-doped ZnIn2S4 photocatalyst, denoted as (Ru,O)-ZIS3, wherein the mass fraction of Ru element was 4.34 wt%.

[0082] Example 4 The method of Example 1 was carried out, except that “0.15 mmol ruthenium trichloride hydrate” in step (1) was replaced with “0.20 mmol ruthenium trichloride hydrate”, and other conditions remained unchanged, to obtain a Ru and O co-doped ZnIn2S4 photocatalyst, denoted as (Ru,O)-ZIS4, wherein the mass fraction of Ru element was 4.56 wt%.

[0083] Example 5 The method of Example 1 was carried out, except that “0.15 mmol ruthenium trichloride hydrate” in step (1) was replaced with “0.21 mmol ruthenium trichloride hydrate”, and other conditions remained unchanged, to obtain a Ru and O co-doped ZnIn2S4 photocatalyst, denoted as (Ru,O)-ZIS5, wherein the mass fraction of Ru element was 4.77 wt%.

[0084] Example 6 The method of Example 1 was carried out, except that “0.15 mmol ruthenium trichloride hydrate” in step (1) was replaced with “0.22 mmol ruthenium trichloride hydrate”, and other conditions remained unchanged, to obtain a Ru and O co-doped ZnIn2S4 photocatalyst, denoted as (Ru,O)-ZIS6, wherein the mass fraction of Ru element was 4.99 wt%.

[0085] Comparative Example 1 The method of Example 1 was implemented, except that polyvinylpyrrolidone and ruthenium trichloride hydrate were not added in step (1), and other conditions remained unchanged, to obtain ZnIn2S4 photocatalyst, denoted as ZIS.

[0086] Comparative Example 2 The method of Example 1 was carried out, except that ruthenium trichloride hydrate was not added in step (1), and other conditions remained unchanged, to obtain an O-doped ZnIn2S4 photocatalyst, denoted as O-ZIS.

[0087] Detection Example 1 The morphology of the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4, the ZnIn2S4 photocatalyst prepared in Comparative Example 1, and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 was analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). The results are as follows: Figure 1 As shown.

[0088] Depend on Figure 1 As shown in the SEM images (a)-(f), the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of this invention, the ZnIn2S4 photocatalyst prepared in Comparative Example 1, and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 all exhibit a micro-flower-like structure composed of clearly distinguishable petals. The size distribution of these hierarchical structures ranges from 300 nm to 1 μm, and the width of a single petal is between 18 and 47 nm. Specifically, the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 has a microsphere structure with a smooth surface, while the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of this invention exhibits a more ordered flower-like arrangement morphology, and nanoparticle clusters appear on the nanosheets due to the Ru nanoparticles formed during the doping process.

[0089] Depend on Figure 1 As shown in the TEM image (g), the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of this invention maintains the micro-flower morphology with clear conductive outlines at the edges of the petals; moreover, Figure 1 The HRTEM image (h) shows that the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 has clear lattice stripes with spacings of 0.32 nm and 0.42 nm, which correspond to the (102) and (006) crystal planes of hexagonal ZnIn2S4, respectively.

[0090] also, Figure 1The EDX plot of (i) confirms the uniform distribution of Ru, O, In, Zn and S elements in the nanoflowers of the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4, while no other impurities were detected, proving the successful doping of Ru and O.

[0091] In summary, the multi-scale characterization by SEM and TEM in this test example shows that Ru and O elements have been successfully doped into the ZnIn2S4 lattice in the Ru and O co-doped ZnIn2S4 photocatalyst prepared in this invention, and the material maintains a micro-flower morphology.

[0092] Detection Example 2 The structures of the Ru and O co-doped ZnIn2S4 photocatalysts prepared in Examples 1-6 of this invention, the ZnIn2S4 photocatalyst prepared in Comparative Example 1, and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 were analyzed using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results are as follows: Figure 2-3 As shown.

[0093] Depend on Figure 2 As can be seen from the content, the diffraction peaks at 21.6°, 27.7°, 39.77°, 47.5°, 52.5°, and 55.6° correspond to the (006), (102), (108), (110), (1012), and (202) crystal planes of the hexagonal ZIS (PDF#72-0773), respectively. The main diffraction peak positions of the Ru and O co-doped ZnIn2S4 photocatalysts prepared in Examples 1-6 of this invention are roughly the same, indicating that these composite materials maintain similar crystal structures.

[0094] However, compared with the ZnIn2S4 photocatalyst prepared in Comparative Example 1, the Ru and O co-doped ZnIn2S4 photocatalysts prepared in Examples 1-6 of this invention showed significantly weaker diffraction peak intensities at 21.6°, 27.7°, 52.5°, and 55.6°, and exhibited peak broadening. According to the Scherrer equation, the broadening and weakening of diffraction peaks indicates a smaller grain size, which is caused by the doping effect inhibiting grain growth. Moreover, the doping of O leads to the substitution of S sites, and the introduction of Ru occupies In lattice positions; the combined effect of these two factors causes lattice distortion.

[11] This ultimately weakens the intensity of the diffraction peaks.

[0095] Depend on Figure 3 The infrared spectrum shows that the ZnIn2S4 photocatalyst prepared in Comparative Example 1 has a photoluminescence density of 1656 cm⁻¹. -1 and 3422 cm -1The presence of a peak at 3393 cm⁻¹ indicates that the unmodified ZIS surface adsorbs moisture and hydroxyl groups (-OH); in the Ru, O co-doped ZnIn₂S₄ photocatalyst prepared in Example 4 and the O-doped ZnIn₂S₄ photocatalyst prepared in Comparative Example 2, the peak at 3393 cm⁻¹ indicates that the unmodified ZIS surface adsorbs moisture and hydroxyl groups (-OH); -1 The increased peak intensity at 1466 cm⁻¹ indicates an increase in the number of surface hydroxyl groups. -1 The new peak at 1287 cm⁻¹ originates from defect states introduced by O atoms or surface modifications; -1 The absorption peak at the point is correlated with the stretching vibration of the S=O bond, proving that S is chemically embedded in the lattice, providing abundant surface active sites for subsequent enhancement of water molecule adsorption and protonation. FTIR spectroscopy confirms that the Ru and O doping-induced increase in surface hydroxyl groups in the Ru and O co-doped ZnIn2S4 photocatalyst prepared in this invention provides abundant active sites for photocatalytic reactions.

[0096] Detection Example 3 The ultraviolet absorption spectra (UV-vis) of the Ru, O co-doped ZnIn2S4 photocatalyst prepared in Example 4, the ZnIn2S4 photocatalyst prepared in Comparative Example 1, and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 were detected using a UV-Vis spectrophotometer. The results are as follows: Figure 4 As shown.

[0097] Depend on Figure 4 The ultraviolet absorption spectrum shows that, compared with the ZnIn2S4 photocatalyst prepared in Comparative Example 1 and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2, the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of this invention exhibits stronger light absorption performance. Its absorption range extends from the visible light region to the near-infrared region, and the absorption edge moves from 550 nm to the red end to 570 nm. This means that Ru and O doping broadens the photoresponse range of the material, thereby improving its photocatalytic efficiency.

[0098] Detection Example 4 Steady-state fluorescence (PL) spectra of the Ru / O co-doped ZnIn2S4 photocatalyst prepared in Example 4, the ZnIn2S4 photocatalyst prepared in Comparative Example 1, and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 were measured using a fluorescence spectrophotometer. The results are as follows: Figure 5 As shown.

[0099] Depend on Figure 5As can be seen, the ZnIn2S4 photocatalyst prepared in Comparative Example 1 exhibits the strongest fluorescence emission peak at 520 nm, indicating that its recombination rate of photogenerated electron-hole pairs is the fastest, and a large number of photogenerated charge carriers recombine before migrating to the catalyst surface to participate in the reaction. The fluorescence intensity of the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 is significantly lower than that of the ZnIn2S4 photocatalyst prepared in Comparative Example 1, indicating that single O doping can suppress the recombination of photogenerated charge carriers to a certain extent and improve the charge separation efficiency. The fluorescence intensity of the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of this invention is further reduced to the lowest level, proving that the co-doping of Ru and O produces a synergistic effect, which can more effectively promote the separation of photogenerated electron-hole pairs and significantly reduce the recombination loss of charge carriers.

[0100] Case 5 Instantaneous photocurrent response was tested on an electrochemical workstation using a standard three-electrode system: FTO conductive glass loaded with Ru and O co-doped ZnIn2S4 photocatalysts prepared in Example 4 of this invention, ZnIn2S4 photocatalysts prepared in Comparative Example 1, and O-doped ZnIn2S4 photocatalysts prepared in Comparative Example 2 were used as the working electrode; a platinum sheet as the counter electrode; an Ag / AgCl electrode as the reference electrode; and a 0.5 mol / L Na2SO4 aqueous solution as the electrolyte. A 300W xenon lamp was used as a simulated sunlight source, with a bias voltage of 0.5V (vs. Ag / AgCl). The test time range was 0–300 s, and multiple periodic lamp switching tests were performed. The photocurrent density change curve over time was recorded. The results are as follows: Figure 6 As shown.

[0101] Depend on Figure 6 As can be seen from the content, when the light is turned on each time, the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4, the ZnIn2S4 photocatalyst prepared in Comparative Example 1, and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 can all rapidly generate a stable photocurrent. After the light is turned off, the photocurrent quickly drops back to the baseline level, indicating that all three photocatalysts have good photoelectric response reversibility and cycle stability. Among them, the ZnIn2S4 photocatalyst prepared in Comparative Example 1 has the lowest photocurrent density, only 0.3 μA·cm. -2 The photocurrent density of the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 was increased to 1.1 μA·cm. -2 The Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of this invention exhibited the highest photocurrent density, at 2.3 μA·cm. -2The photocurrent density is 7.7 times that of the ZnIn2S4 photocatalyst prepared in Comparative Example 1 and 2.1 times that of the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2, respectively. The higher photocurrent density means that more photogenerated carriers can be effectively separated and migrate to the catalyst surface to participate in the redox reaction, indicating that the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of this invention has a stronger electron-hole pair separation capability. This further confirms that Ru and O work together in the Ru and O co-doped ZnIn2S4 photocatalyst of this invention, promoting the light absorption and charge separation capabilities of the photocatalyst, thereby achieving a highly efficient and stable photocatalytic hydrogen production effect.

[0102] Application Example 1 The photocatalytic hydrogen production experiment was conducted in a fully sealed gas circulation system, using a 250 mL quartz photoreactor. The specific steps are as follows: S1. Weigh 100 mg of the Ru and O co-doped ZnIn2S4 photocatalysts prepared in Examples 1-6 of this invention, the ZnIn2S4 photocatalysts prepared in Comparative Example 1, and the O-doped ZnIn2S4 photocatalysts prepared in Comparative Example 2, respectively, and uniformly disperse them in 20 mL of triethanolamine (TEOA) (20 vol%) aqueous solution, and add 1.5 g of NaOH. S2. After purging the reaction system with nitrogen for 30 min, a photocatalytic hydrogen production reaction was carried out under visible light irradiation (λ>420 nm). The reaction temperature was controlled at 25℃ using a circulating condenser. The hydrogen produced was quantitatively analyzed using a gas chromatograph (FULI, GC 9790plus) equipped with a carbon molecular sieve packed column and a thermal conductivity detector (TCD). Nitrogen was used as the carrier gas during the test, and hydrogen production data were collected every 30 min. The results are as follows: Figure 7 As shown in (a)-(b).

[0103] Depend on Figure 7 As shown in (a), when Ru atoms are incorporated, the hydrogen production activity of the Ru- and O co-doped ZnIn2S4 photocatalysts prepared in Examples 1-6 of this invention all surpasses that of the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2, fully demonstrating that Ru plays a key role in improving hydrogen production performance. Theoretical analysis shows that Ru atoms readily replace the interstitial sites of In in the crystal lattice, while O atoms tend to replace S sites, thereby enhancing the interfacial electron transfer efficiency.

[0104] Depend on Figure 7 As shown in (b), the hydrogen production rate first increases and then decreases with increasing Ru doping concentration. The hydrogen production rate reaches its maximum value of 1.7234 mmol·g when the Ru doping concentration is 0.20 mmol. -1 ·h-1 The improved performance is due to the increased surface reaction sites introduced by Ru doping, which facilitates the separation of photogenerated electron-hole pairs. However, as the Ru doping concentration continues to increase and exceeds 0.20 mmol, hydrogen production decreases. This is because excess Ru aggregates on the surface; these nanoparticles not only block visible light but also hinder carrier migration, exacerbating charge recombination.

[0105] Application Example 2 Cyclic performance tests were conducted on the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of this invention, the ZnIn2S4 photocatalyst prepared in Comparative Example 1, and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2. The tests were performed in the same manner as in Application Example 1, except that each cycle lasted 3 hours, and a total of 4 cycles were performed. The results are as follows: Figure 7 As shown in (c).

[0106] Depend on Figure 7 As shown in (c), after 4 cycles, the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 still retained 86.95% of its original photocatalytic performance; the ZnIn2S4 photocatalyst prepared in Comparative Example 1 retained 54.3% of its original photocatalytic performance; and the O-doped ZnIn2S4 photocatalyst prepared in Comparative Example 2 retained 71.2% of its original photocatalytic performance. It can be seen that the Ru and O co-doped ZnIn2S4 photocatalyst of the present invention has good photocatalytic stability and good resistance to photocorrosion.

[0107] Application Example 3 The apparent quantum efficiency (AQE) of the Ru / O co-doped ZnIn2S4 photocatalyst prepared in Example 4 of this invention was tested. The procedure was the same as in Application Example 1, except that bandpass filters of 400, 420, 450, 500, and 550 nm were used to filter the xenon lamp source to obtain monochromatic visible light. The hydrogen yield and apparent quantum efficiency were measured over 4 hours at each wavelength. The results are as follows: Figure 7 As shown in (d).

[0108] Depend on Figure 7As shown in section (d), the Ru and O co-doped ZnIn2S4 photocatalyst prepared in Example 4 achieves a maximum AQE of 12.88% near 400 nm (UV-Vis interface), indicating that the Ru and O co-doped ZnIn2S4 photocatalyst prepared in this invention exhibits high photogenerated charge separation efficiency and catalytic activity at this wavelength. With increasing wavelength (420~550 nm), the AQE gradually decreases, indicating that the Ru and O co-doped ZnIn2S4 photocatalyst prepared in this invention has reduced utilization efficiency for longer wavelengths of light. Experimental results demonstrate that Ru and O co-doping broadens the photoresponse range of ZIS, enhances the absorption capacity of ZIS for visible light, promotes charge separation, reduces electron-hole recombination, and improves the AQE at shorter wavelengths.

[0109] Based on the above photocatalytic performance test and electrochemical characterization results, a reasonable photocatalytic reaction mechanism for the Ru, O co-doped ZnIn2S4 photocatalyst of this invention is proposed. Taking the Ru, O co-doped ZnIn2S4 photocatalyst prepared in Example 4 as an example, ... Figure 8 As shown.

[0110] Under sunlight irradiation, electrons in ZIS nanosheets are excited and jump to the conduction band, generating holes in the valence band. Photogenerated electron-hole pairs are effectively excited and separated. After migrating to the catalyst surface, the photogenerated holes undergo an oxidation reaction with TEOA. Since the valence band position of the Ru / O co-doped ZnIn₂S₄ photocatalyst is 1.86 V vs NHE, this potential is insufficient to oxidize OH⁻. - Oxidation produces ·OH (standard potential 1.89 V vs NHE). Therefore, holes are primarily consumed through the oxidation of TEOA, and the protons (H⁺) released in this process provide a proton source for the subsequent hydrogen evolution reaction. Photogenerated electrons migrate to the catalyst's conduction band and then rapidly migrate to surface active sites via electron transfer channels constructed by Ru and O atoms. The co-doping of Ru and O atoms introduces shallow-level impurity states into the ZIS lattice, forming a doping-induced charge rearrangement structure. This dual-element co-doping strategy constructs highly efficient electron transfer channels within ZIS, effectively promoting the separation and directional migration of photogenerated carriers. Photogenerated electrons migrating to the surface reduce protons generated from water splitting and those released during TEOA oxidation to hydrogen. In summary, the (Ru,O)-ZIS4 photocatalyst, through the synergistic effect of Ru and O dual-element co-doping, achieves optimized band structure, enhanced charge separation, and improved surface reactivity, significantly improving photocatalytic hydrogen production performance.

[0111] In summary, this invention addresses the inherent defects of pure ZnIn2S4, such as high photogenerated carrier recombination rate, low charge separation efficiency, and insufficient light absorption regulation or excessive carrier recombination due to single-element doping. It develops a Ru / O co-doped ZnIn2S4 photocatalyst. By substituting In sites in the ZnIn2S4 lattice with Ru to construct an efficient charge trap, electron-hole pair recombination is significantly suppressed. Furthermore, by substituting S sites with O and hybridizing valence band orbitals to narrow the bandgap, the light absorption edge is redshifted to 570 nm, broadening the photoresponse range to the near-infrared region. These two methods synergistically achieve band structure optimization and enrichment of surface active sites. The Ru / O co-doped ZnIn2S4 photocatalyst of this invention achieves a photocatalytic hydrogen production rate of 1.7234 mmol·g⁻¹. -1 ·h -1 The apparent quantum efficiency at 400 nm wavelength is 12.88%, far superior to pure ZnIn2S4 and single O-doped samples. After four cycles, it retains 86.95% of its initial activity, exhibiting both high catalytic activity and excellent resistance to photocorrosion. This invention employs a one-step hydrothermal method to simultaneously complete crystal growth and dual-element doping. The process is simple, the raw materials are readily available, the reaction conditions are mild, no complex post-processing is required, and it exhibits good reproducibility and is easy to scale up. This invention provides a new approach for the development of high-performance sulfide-based photocatalysts and has broad industrial application prospects in the field of visible light-driven photocatalytic water splitting for hydrogen production.

[0112] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0113] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0114] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A Ru, O co-doped ZnIn2S4 photocatalyst, characterized in that, The Ru and O co-doped ZnIn2S4 photocatalyst uses hexagonal ZnIn2S4 as the matrix, with Ru doping replacing the In sites in the ZnIn2S4 lattice and O doping replacing the S sites in the ZnIn2S4 lattice.

2. The Ru, O co-doped ZnIn2S4 photocatalyst according to claim 1, characterized in that, The mass fraction of Ru in the Ru, O co-doped ZnIn2S4 photocatalyst is 3-5 wt%.

3. The Ru, O co-doped ZnIn2S4 photocatalyst according to claim 1 or 2, characterized in that, The Ru and O co-doped ZnIn2S4 photocatalyst has a micro-flower-like hierarchical structure assembled from two-dimensional nanosheets; The size of the micro-flower-like hierarchical structure is 300~1000 nm; The width of the two-dimensional nanosheet is 18~47nm.

4. A method for preparing a Ru, O co-doped ZnIn2S4 photocatalyst as described in any one of claims 1-3, characterized in that, The preparation method includes: in the presence of a solvent, first adding zinc salt, indium salt and sulfur source to the solvent to dissolve, then adding oxygen source and ruthenium salt to mix, carrying out a hydrothermal reaction, cooling, washing, and drying to obtain Ru and O co-doped ZnIn2S4 photocatalyst.

5. The preparation method according to claim 4, characterized in that, The solvent is water; The zinc salt is selected from one or more of zinc chloride, zinc acetate, and zinc acetate; The indium salt is indium trichloride tetrahydrate and / or indium nitrate; The sulfur source is selected from one or more of thioacetamide, thiourea, and L-cysteine; The oxygen source is selected from one or more of polyvinylpyrrolidone, ethylene glycol, and citric acid; The ruthenium salt is selected from one or more of ruthenium trichloride hydrate, ruthenium acetate, and ruthenium acetylacetonate.

6. The preparation method according to claim 4 or 5, characterized in that, The molar ratio of the zinc salt, indium salt, sulfur source, oxygen source and ruthenium salt is 1:1.8~2.2:7~9:0.002~0.005:0.15~0.

22.

7. The preparation method according to any one of claims 4-6, characterized in that, The dissolution conditions include: a temperature of 15~30℃, a time of 20~40min, and a stirring rate of 300~500rpm; The mixing conditions include: a temperature of 15~30℃, a time of 15~30min, and a stirring speed of 300~500rpm; The conditions for the hydrothermal reaction include: a heating rate of 3~8℃ / min, a final reaction temperature of 160~200℃, and a constant temperature holding time of 12~24h.

8. The preparation method according to any one of claims 4-7, characterized in that, The temperature is then cooled to 15~30℃; The washing conditions include: washing with deionized water and anhydrous ethanol 3 to 5 times each, and the washing method is to alternate between deionized water and anhydrous ethanol. The drying conditions include: vacuum conditions, a temperature of 60~100℃, and a time of 8~16h.

9. The application of a Ru, O co-doped ZnIn2S4 photocatalyst as described in any one of claims 1-3 in photocatalytic water splitting for hydrogen production.

10. A method for photocatalytic water splitting to produce hydrogen, characterized in that, The method includes: 1) Disperse the photocatalyst in an aqueous sacrificial agent solution and add an alkaline regulator to obtain the reaction solution; 2) Under an inert atmosphere, the reaction solution obtained in step 1) is subjected to photocatalytic hydrogen evolution reaction under visible light irradiation; In step 1), the photocatalyst is the Ru, O co-doped ZnIn2S4 photocatalyst according to any one of claims 1-3; In step 1), the sacrificial agent is selected from one or more of triethanolamine, methanol, lactic acid, and sodium sulfide / sodium sulfite compound reagent; In step 1), the volume fraction of the sacrificial agent aqueous solution is 15-25%; In step 1), the ratio of the photocatalyst to the sacrificial agent aqueous solution is 80~120 mg:20 mL; In step 1), the alkali adjuster is sodium hydroxide and / or potassium hydroxide; In step 1), the ratio of the alkali adjuster to the sacrificial agent aqueous solution is 1.2~1.8g:20mL; In step 2), the inert atmosphere is a nitrogen atmosphere and / or an argon atmosphere; In step 2), the wavelength range of the visible light is λ > 420 nm; In step 2), the temperature of the photocatalytic hydrogen evolution reaction is 15~30℃.

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