ZnIn2S4@Au Hierarchical Heterostructure Photocatalyst Rich in Sulfur Vacancies, Its Preparation Method and Application

Abstract

The present invention belongs to the field of photocatalysis technology, and particularly relates to a sulfur vacancy-rich ZnIn2S4@Au hierarchical heterostructure photocatalyst, a preparation method thereof, and an application thereof. In this method, sulfur vacancy-rich ZnIn2S4 microflowers are dispersed in an ethanol aqueous solution, and then chloroauric acid solution is added to obtain a suspension. Finally, the suspension is irradiated under ultraviolet-visible light. After the irradiation is completed, centrifugation, washing, and drying are carried out to finally obtain a sulfur vacancy-rich ZnIn2S4@Au hierarchical heterostructure photocatalyst. The preparation method of the present invention has mild reaction conditions and is simple and easy to operate. Compared with single ZnIn2S4 microflowers, the above-mentioned synergistic effect enables ZIS@Au-0.4 to have good photocatalytic performance for CO2 reduction to CO.

Description

Technical Field

[0001] The present invention belongs to the technical field of photocatalysis, and particularly relates to a sulfur vacancy-rich ZnIn2S4@Au hierarchical heterostructure photocatalyst, a preparation method thereof, and an application thereof. Background Art

[0002] In recent decades, the rapid development of industrialization has led to the overconsumption of fossil fuels, causing serious energy shortages and a large amount of carbon dioxide (CO2) emissions. Reducing CO2 to hydrocarbon fuels using solar energy and photocatalysts is a promising strategy that is expected to solve the above two problems simultaneously. Therefore, it has received extensive attention. Zinc indium sulfide (ZnIn2S4) has been widely studied in photocatalytic CO2 reduction due to its suitable band gap (2.2 - 2.8 eV), good reduction ability, layered structure, excellent chemical stability, etc. However, the photocatalytic CO2 reduction performance of single ZnIn2S4 (ZIS) is still not ideal, mainly due to its insufficient light absorption ability, serious recombination of photo-generated carriers, and insufficient active sites (which is not conducive to the adsorption and activation of CO2). Summary of the Invention

[0003] The object of the present invention is to solve the deficiencies of the prior art and provide a ZnIn2S4@Au hierarchical heterostructure photocatalyst rich in sulfur vacancies, its preparation method and application. Coupling plasmonic metal nanoparticles with semiconductors and vacancy engineering are used to overcome the above-mentioned inherent drawbacks. On the one hand, for the plasmonic metal-semiconductor system, the surface plasmon resonance (SPR) effect of metal nanoparticles (NPs) and the synergistic effect of the Schottky junction at their heterointerfaces can be utilized. For example, plasmonic semiconductor photocatalysts (Au / TiO2, Ag / In2O3, TaON@Ni NPs, Bi4O5I2@Cu NPs) combine these two different advantages and exhibit significantly improved CO2 photoreduction activity. Specifically, the SPR effect of plasmonic metals can extend the light absorption range to the near-infrared, resulting in the generation of hot electrons. A part of the hot electrons transfer to the conduction band (CB) of the (n-type) semiconductor through the Schottky barrier of the semiconductor / plasmonic metal, and increase the electron density in the conduction band of the semiconductor, which is beneficial to the half-reaction of CO2 reduction. In addition, the Schottky junction can effectively prevent the backflow of electrons from the semiconductor to the plasmonic metal, and promote the migration of photo-generated holes in the valence band (VB) of the semiconductor to the plasmonic metal for H2O oxidation, further promoting the photocatalytic process. However, due to its high contact resistance, the Schottky barrier can also inhibit the free flow of carriers at the heterointerfaces. For plasmonic metal-semiconductor photocatalysts, the hot electron injection process occurs only when the kinetic energy of the hot electrons is higher than the Schottky barrier height (SBH), and the SBH can be evaluated by subtracting the electron affinity (χ) of the semiconductor from the work function (Φ) of the plasmonic metal. χ is defined as the energy required to transfer an electron from the bottom of its CB (i.e., the vacuum level) to the surface of the semiconductor. Hot electrons with kinetic energy lower than the SBH cannot cross the Schottky barrier and recombine with holes in the metal, reducing the performance of the photocatalyst. Therefore, the SBH is a key parameter for plasmon-induced photocatalysis, and optimizing the SBH of plasmonic ZIS-based photocatalysts is an effective means to accelerate the plasmon-driven hot electron injection process. Reasonable design of the energy band structure of ZIS is crucial for regulating the SBH at the interface.

[0004] On the other hand, S vacancy engineering can change the electronic structure of metal sulfide semiconductors, cause redistribution of charge density, lower the CB of the semiconductor, regulate the SBH, and thus promote the cross-boundary migration of electrons. In addition, S vacancy engineering can also increase the density of active sites, which is beneficial to the adsorption and activation of CO2. In addition, the positively charged S vacancy (V S ) can act as an electron trap to capture photo-induced electrons and hinder the recombination of photo-generated carriers.

[0005] Specifically, the following technical solutions are adopted:

[0006] On the one hand, the present invention provides a method for preparing a ZnIn2S4@Au hierarchical heterostructure photocatalyst rich in sulfur vacancies, comprising the following steps:

[0007] Disperse the ZnIn2S4 microflowers rich in sulfur vacancies in an ethanol aqueous solution, then add chloroauric acid solution to obtain a suspension, and finally irradiate the suspension under ultraviolet-visible light. After the irradiation is completed, centrifuge, wash, and dry to finally obtain a ZnIn2S4@Au hierarchical heterostructure photocatalyst rich in sulfur vacancies.

[0008] In the present invention, Au NPs are in-situ photodeposited on the ZIS microflowers (V S R-ZIS MFs) self-assembled from nanosheets and rich in V S to successfully construct a V S R-ZIS@Au hierarchical heterostructure photocatalyst. Among them, the hierarchical microflowers self-assembled from nanosheets have abundant active sites due to their high surface area, which is conducive to the adsorption and activation of molecules participating in the photocatalytic reaction. Experimental results show that the optimal photocatalyst (V S R-ZIS@Au-0.4) has excellent photocatalytic CO2 reduction performance, mainly due to: (1) introducing abundant V S to lower the CB of V S R-ZIS, thereby reducing the SBH of V S R-ZIS@Au-0.4, accelerating the hot electron injection process, and V S can act as an electron trap to inhibit the recombination of photogenerated electron-hole pairs; (2) introducing V S can promote the desorption of CO* from the surface of V S R-ZIS@Au-0.4.

[0009] As a further preferred embodiment, the volume percentage of ethanol in the above ethanol aqueous solution is 20%-60%.

[0010] As a further preferred embodiment, the dosage ratio of the above ZnIn2S4 microflowers to the chloroauric acid solution is 0.3 g: 0.7 mL - 2.1 mL. The concentration of the chloroauric acid solution is 0.855 g / L. More preferably, the dosage ratio of ZnIn2S4 microflowers to the chloroauric acid solution is 0.3 g: 1.4 mL.

[0011] As a further preferred embodiment, when irradiating under ultraviolet-visible light, the intensity of the xenon lamp is 300 W, and the irradiation time is 2 h - 6 h.

[0012] As a further preferred embodiment, the ZnIn2S4 microflowers rich in sulfur vacancies are obtained by the following steps:

[0013] Firstly, zinc chloride is dissolved in water, and then indium chloride tetrahydrate and thioacetamide are added in sequence. After complete dissolution, a hydrothermal reaction is carried out. After the reaction is completed, the mixture is centrifuged, washed, and freeze-dried to obtain ZnIn2S4 microflowers rich in sulfur vacancies.

[0014] As a further preferred embodiment, the molar ratio of zinc chloride, indium chloride tetrahydrate and thioacetamide is 1:2:8-12. More preferably, the molar ratio of zinc chloride, indium chloride tetrahydrate and thioacetamide is 1:2:8.

[0015] As a further preferred embodiment, the temperature of the hydrothermal reaction is 160°C-200°C, and the reaction time is 12 h-18 h. More preferably, the temperature of the hydrothermal reaction is 180°C, and the reaction time is 18 h.

[0016] The first aspect of the present invention also provides a sulfur vacancy-rich ZnIn2S4@Au hierarchical heterogeneous structure photocatalyst prepared by the above preparation method. The sulfur vacancy-rich ZnIn2S4@Au hierarchical heterogeneous structure photocatalyst can be used in catalytic CO2 reduction.

[0017] The beneficial effects of the present invention are:

[0018] The preparation method of the present invention has mild reaction conditions and is simple and easy to operate; S V in R-ZIS@Au heterostructure S The presence of can induce the formation of defect states and act as electron traps to effectively suppress the recombination of photogenerated carriers. In addition, V S The introduction of V S The surface states in the band gap of R-ZIS MFs reduce their CB and V S SBH of R-ZIS@Au-0.4. Both synergistic effects can improve V S The electron density on the surface of R-ZIS@Au-0.4 promotes the photocatalytic CO2 reduction reaction. S Promote the desorption of CO* from the photocatalyst surface. Therefore, compared with single ZIS microflowers, the above synergistic effect makes ZIS@Au-0.4 have good performance in photocatalytic CO2 reduction to CO. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Shown is V S R-ZIS@Au-0.2, V S R-ZIS@Au-0.4, V S R-ZIS@Au-0.6, V S R-ZIS MFs, VS P-ZIS MFs, V S X-ray diffraction (XRD) patterns of P-ZIS@Au-0.4).

[0020] Figure 2 As shown is V S R-ZIS MFs and V S Scanning electron microscope (SEM) images, transmission electron microscope (TEM) images, high-resolution transmission electron microscope (HRTEM) images, and elemental mapping images of R-ZIS@Au-0.4; among them, Figure 2 (a-b) are SEM images of V S R-ZIS MFs; Figure 2 (c-d) are the TEM and HRTEM images of V S R-ZIS MFs respectively; Figure 2 (e) is the SEM image of V S R-ZIS@Au-0.4; Figure 2 (f-g) are the TEM images of V S R-ZIS@Au-0.4; Figure 2 (h) is the HRTEM image of V S R-ZIS@Au-0.4; Figure 2 (i) is the elemental mapping image of V S R-ZIS@Au-0.4.

[0021] Figure 3 As shown is V S R-ZIS@Au-0.4, V S R-ZIS MFs, V S P-ZIS MFs, V S X-ray photoelectron spectroscopy (XPS) spectra and electron paramagnetic resonance (EPR) spectra of P-ZIS@Au-0.4; among them, Figure 3 (a-e) are the XPS spectra of V S R-ZIS@Au-0.4, V S R-ZIS MFs, V S P-ZIS MFs; Figure 3 (f) is the EPR spectrum of V S R-ZIS@Au-0.4, V S R-ZIS MFs, V S P-ZIS MFs, V S P-ZIS@Au-0.4.

[0022] Figure 4 As shown are the photocatalytic CO2 reduction performance test images of the products of Examples 1-3 and Comparative Example 1; among them, Figure 4(a - b)V S R-ZIS@Au-0.2, V S R-ZIS@Au-0.4, V S R-ZIS@Au-0.6, V S R-ZIS MFs, V S P-ZIS MFs, V S Photocatalytic CO₂ reduction performance test chart of (P-ZIS@Au-0.4); Figure 4 (c) is V S Photocatalytic CO₂ reduction cycle test chart of R-ZIS@Au-0.4, Figure 4 (d) is V S Photocatalytic CO₂ reduction performance test chart of R-ZIS@Au-0.4 under different conditions.

[0023] Figure 5 The UV-visible absorption spectra, transient photocurrent response curves, transient photocurrent response curves, electrochemical impedance spectra, photoluminescence spectra, and time-resolved fluorescence spectra of the products of Examples 1-3 and Comparative Example 1 are shown; Figure 5 (a) is V S R-ZIS@Au-0.2, V S R-ZIS@Au-0.4, V S R-ZIS@Au-0.6, V S R-ZIS MFs, V S P-ZIS MFs, V S UV-visible absorption spectrum of P-ZIS@Au-0.4; Figure 5 (b) is V S R-ZIS@Au-0.4, ZV S Transient photocurrent response curve of R-ZIS MFs, Au NPs (λ > 700 nm); Figure 5 (c) is V S R-ZIS@Au-0.4, V S R-ZIS MFs, V S P-ZIS MFs, V S Transient photocurrent response curve of P-ZIS@Au-0.4 (λ > 420 nm); Figure 5 (d) is V S R-ZIS@Au-0.4, V S R-ZISMFs, V S P-ZIS MFs, V S Electrochemical impedance spectrum of P-ZIS@Au-0.4; Figure 5 (e) is V SR-ZIS@Au-0.4, V S R-ZIS MFs, V S P-ZIS MFs, V S Photoluminescence spectra of P-ZIS@Au-0.4); Figure 5 (f) is V S R-ZIS@Au-0.4, V S R-ZIS MFs, V S P-ZIS MFs, V S Time-resolved fluorescence spectra of P-ZIS@Au-0.4.

[0024] Figure 6 As shown, V S R-ZIS MFs, V S P-ZIS MFs, V S P-ZIS@Au-0.4, V S CO2 adsorption isotherm diagrams, CO2 temperature-programmed desorption curves, and in-situ diffuse reflectance Fourier transform infrared spectra of photocatalytic CO2 reduction of R-ZIS@Au-0.4; among them Figure 6 (a) is V S R-ZIS MFs, V S P-ZIS MFs, V S P-ZIS@Au-0.4, V S CO2 adsorption isotherm diagram of R-ZIS@Au-0.4; Figure 6 (b) is V S R-ZIS@Au-0.4, V S R-ZIS MFs, V S CO2 temperature-programmed desorption curve of P-ZIS MFs; Figure 6 (c) is V S In-situ diffuse reflectance Fourier transform infrared spectrum of photocatalytic CO2 reduction of R-ZIS@Au-0.4. Detailed implementation manners

[0025] The concept, specific structure, and technical effects of the present invention will be clearly and completely described below in combination with embodiments and drawings to fully understand the purpose, scheme, and effects of the present invention. It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other.

[0026] Embodiment 1

[0027] A preparation method of a sulfur vacancy-rich ZnIn2S4@Au hierarchical heterostructure photocatalyst, which specifically includes the following steps:

[0028] (1) Synthesize VS R-ZIS MFs (ZnIn2S4 microflowers rich in sulfur vacancies)

[0029] First, add 1 mmol of zinc chloride to 40 mL of deionized water, and ultrasonicate it for 10 min until it is completely dissolved to obtain solution A. Then, add 2 mmol of indium chloride tetrahydrate to solution A, and ultrasonicate it for 10 min until it is completely dissolved to obtain solution B. Then, add 8 mmol of thioacetamide to solution B, stir magnetically for 0.5 h, and then transfer the mixture to a 100 mL hydrothermal reactor. Perform hydrothermal reaction at 180 °C for 18 h to obtain a yellow precipitate. Centrifuge at 10000 rpm for 5 min, wash it with deionized water 3 times, and finally dry it in a freeze dryer for 12 hours to obtain V S R-ZIS MFs.

[0030] (2)Synthesis of V S R-ZIS@Au heterostructure photocatalyst (ZnIn2S4@Au hierarchical heterostructure photocatalyst rich in sulfur vacancies)

[0031] Add 0.3 g of the prepared V S R-ZIS MFs to 100 mL of an ethanol aqueous solution with a volume ratio of 20%, and ultrasonically stir until it is completely dispersed to form suspension I. Then, add 0.7 mL of chloroauric acid solution (0.855 g / L) to suspension I to form suspension II, and stir magnetically for 0.5 h. Finally, irradiate the suspension under ultraviolet-visible light at 300 W with vigorous stirring for 2 h, and then centrifuge, wash, and dry to obtain V S R-ZIS@Au heterostructure photocatalyst.

[0032] In this example, it was measured that the mass ratio of Au to V S R-ZIS in the R-ZIS@Au heterostructure photocatalyst is 0.2%. Mark this V S R-ZIS@Au heterostructure photocatalyst as V S R-ZIS@Au-0.2. S R-ZIS@Au-0.2.

[0033] Example 2

[0034] A preparation method of a ZnIn2S4@Au hierarchical heterostructure photocatalyst rich in sulfur vacancies, which specifically includes the following steps:

[0035] (1)Synthesis of V S R-ZIS MFs (ZnIn2S4 microflowers rich in sulfur vacancies)

[0036] First, 1 mmol of zinc chloride was added to 40 mL of deionized water, and it was ultrasonically treated for 10 min until it was completely dissolved to obtain solution A. Then, 2 mmol of indium chloride tetrahydrate was added to solution A, and it was ultrasonically treated for 10 min until it was completely dissolved to obtain solution B. Then, 8 mmol of thioacetamide was added to solution B, and it was magnetically stirred for 0.5 h. Then, the mixture was transferred to a 100 mL hydrothermal reactor, and hydrothermal reaction was carried out at 180 °C for 18 h to obtain a yellow precipitate, which was centrifuged at a high speed of 10000 rpm for 5 min, washed 3 times with deionized water, and finally dried in a freeze dryer for 12 hours, thereby obtaining V S R-ZIS MFs.

[0037] (2)Synthesis of V S R-ZIS@Au heterostructure photocatalyst (sulfur vacancy-rich ZnIn2S4@Au hierarchical heterostructure photocatalyst)

[0038] 0.3 g of the prepared V S R-ZIS MFs was added to 100 mL of an ethanol aqueous solution with a volume ratio of 20%, and it was ultrasonically stirred until it was completely dispersed to form suspension I. Then, 1.4 mL of chloroauric acid solution (0.855 g / L) was added to suspension I to form suspension II, and it was magnetically stirred for 0.5 h. Finally, the suspension was irradiated under ultraviolet-visible light at 300 W with vigorous stirring for 2 h, and then centrifuged, washed, and dried to obtain V S R-ZIS@Au heterostructure photocatalyst.

[0039] In this example, it was measured that the mass ratio of Au to V S R-ZIS in the R-ZIS@Au heterostructure photocatalyst was 0.4%. This V S R-ZIS@Au heterostructure photocatalyst was labeled as V S R-ZIS@Au-0.4. S

[0040] Example 3

[0041] A preparation method of a sulfur vacancy-rich ZnIn2S4@Au hierarchical heterostructure photocatalyst specifically includes the following steps:

[0042] (1)Synthesis of V S R-ZIS MFs (sulfur vacancy-rich ZnIn2S4 microflowers)

[0043] First, add 1 mmol of zinc chloride to 40 mL of deionized water, and ultrasonicate it for 10 min until it is completely dissolved to obtain solution A. Then, add 2 mmol of indium chloride tetrahydrate to solution A, and ultrasonicate it for 10 min until it is completely dissolved to obtain solution B. Then, add 8 mmol of thioacetamide to solution B, stir magnetically for 0.5 h, and then transfer the mixture to a 100 mL hydrothermal reactor. Carry out a hydrothermal reaction at 180 °C for 18 h to obtain a yellow precipitate. Centrifuge and separate it at a high speed of 10000 rpm for 5 min, wash it 3 times with deionized water, and finally dry it in a freeze dryer for 12 hours to obtain V S R-ZIS MFs.

[0044] (2)Synthesis of V S R-ZIS@Au heterostructure photocatalyst (sulfur vacancy-rich ZnIn2S4@Au hierarchical heterostructure photocatalyst)

[0045] Add 0.3 g of the prepared V S R-ZIS MFs to 100 mL of an ethanol aqueous solution with a volume ratio of 20%, and ultrasonically stir until it is completely dispersed to form a suspension of type I; then add 2.1 mL of chloroauric acid solution (0.855 g / L) to the suspension of type I to form a suspension of type II, and stir magnetically for 0.5 h; finally, irradiate the suspension under intense stirring with ultraviolet-visible light at 300 W for 2 h, and after centrifugation, washing, and drying, obtain V S R-ZIS@Au heterostructure photocatalyst.

[0046] In this example, it was measured that the mass ratio of Au to V S in the R-ZIS@Au heterostructure photocatalyst was 0.6%. Mark this V S R-ZIS@Au heterostructure photocatalyst as V S R-ZIS@Au-0.6. S R-ZIS@Au-0.6.

[0047] Comparative Example 1

[0048] To prove that introducing abundant V S can reduce the CB of V S R-ZIS MFs, thereby reducing the SBH of V S R-ZIS@Au-0.4, accelerating the hot electron injection process, and it can also act as an electron trap to inhibit the recombination of photo-generated electron-hole pairs; in addition, introducing V S can promote the desorption of CO* from the surface of V S R-ZIS@Au-0.4. ZIS microflowers containing a small amount of sulfur vacancies (V SP-ZIS MFs), Au NPs, and ZnIn2S4@Au hierarchical heterostructure photocatalyst with a small amount of sulfur vacancies (V S P-ZIS@Au-0.4).

[0049] V S Preparation of V

[0050] P-ZIS MFs specifically includes the following steps: S First, add 1 mmol of zinc chloride to 40 mL of deionized water, ultrasonicate it for 10 min until it is completely dissolved to obtain solution A. Then, add 2 mmol of indium chloride tetrahydrate to solution A and ultrasonicate it for 10 min until it is completely dissolved to obtain solution B. Then, add 6 mmol of thioacetamide to solution B, stir magnetically for 0.5 h, and then transfer the mixture to a 100 mL hydrothermal reactor. Hydrothermally react at 180 °C for 18 h to obtain a yellow precipitate. Centrifuge at 10000 rpm for 5 min, wash it with deionized water 3 times, and finally dry it in a freeze dryer for 12 hours to obtain V S P-ZIS MFs.

[0051] Preparation of Au NPs specifically includes the following steps:

[0052] (1) Add 244 mL of HAuCl4· solution (0.855 g / L) to 50 mL of deionized water and ultrasonically stir until it is completely dispersed;

[0053] (2) Gradually add 20 mL of the prepared NaBH4 solution (the molar ratio of Au to NaBH4 is 1:10) dropwise to the above solution;

[0054]

[0055] V S The preparation process of P-ZIS@Au-0.4 is the same as that of Example 2, and the only difference is that V S P-ZIS MFs are replaced with VR-ZIS MFs.

[0056] The samples of the above Examples 1-3 and the comparative examples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible absorption spectroscopy, photoelectrochemical tests, CO2 adsorption isotherms, CO2 temperature-programmed desorption curves, and in-situ diffuse reflectance Fourier transform infrared spectroscopy of CO2 photoreduction.

[0057] Figure 1 For VS R-ZIS@Au-0.2, V S R-ZIS@Au-0.4, V S R-ZIS@Au-0.6, V S R-ZIS MFs, V S P-ZIS MFs, V S XRD pattern of P-ZIS@Au-0.4. It can be seen from Figure 1 that V S R-ZIS MFs, V S XRD patterns of both R-ZIS MFs and P-ZIS MFs are the spectra of hexagonal ZIS, and no diffraction peaks of any impurities can be detected, indicating that the obtained ZIS MFs have high purity; in addition, after introducing Au NPs, V S R-ZIS@Au-0.2, V S R-ZIS@Au-0.4, V S R-ZIS@Au-0.6 V S XRD spectrum of P-ZIS@Au-0.4 retains the diffraction peaks of ZIS, while the diffraction peaks of Au are not obvious, which may be due to the low content and good dispersion of Au on the surface of ZIS MFs.

[0058] Figure 2 (a), Figure 2 (b) are SEM images of V S R-ZIS MFs, Figure 2 (c), Figure 2 (d) are TEM and HRTEM images of V S R-ZIS MFs respectively, which prove its hierarchical microflower structure (self-assembled from nanosheets). Figure 2 (e) is the SEM image of V S R-ZIS@Au-0.4; Figure 2 (f, g) and Figure 2 (h) are TEM and HRTEM images of V S R-ZIS@Au-0.4 respectively, indicating that Au NPs are anchored on V S R-ZIS MFs. Figure 2 (i) is the elemental distribution map of V S R-ZIS@Au-0.4, indicating that the example (V S R-ZIS@Au-0.4) contains four elements: Zn, In, S, and Au, and Au is uniformly distributed on the entire V S R-ZIS MFs.

[0059] Figure 3 For V S R-ZIS@Au-0.4, VS P-ZIS MFs, V S XPS spectra of R-ZIS MFs; as shown in Figure 3 (b-d), compared with V S P-ZIS MFs, for this V S R-ZIS MFs, the binding energies of Zn 2p, In 3d, and S 2s shifted negatively by 0.1 eV, indicating that V S In R-ZIS MFs, due to more S atoms escaping, there are abundant S vacancies. At the same time, relative to V S R-ZIS MFs, for V S the peaks in R-ZIS@Au-0.4 shifted positively, proving that V S after R-ZIS MFs were in close contact with Au NPs, there was an electronic interaction at the interface. Figure 3 (f) shows the EPR spectra of V S R-ZIS@Au-0.4, V S R-ZIS MFs, V S P-ZIS MFs, V S P-ZIS@Au-0.4, confirming that V S R-ZIS@Au-0.4 has abundant sulfur vacancies, while V S P-ZIS MFs have a small amount of sulfur vacancies.

[0060] Figure 5 (a) shows the UV-visible absorption spectra of V S R-ZIS@Au-0.2, V S R-ZIS@Au-0.4, V S R-ZIS@Au-0.6, V S R-ZIS MFs, V S P-ZIS MFs, V S P-ZIS@Au-0.4, indicating that V S R-ZIS@Au-0.2, V S R-ZIS@Au-0.4, V S R-ZIS@Au-0.6 have stronger light absorption ability. Figure 5 (b) shows the transient photocurrent response curves of V S R-ZIS@Au-0.4, V S R-ZIS MFs, Au NPs, proving that under visible-near infrared light (λ>700 nm) irradiation, V S R-ZIS@Au-0.4 can generate hot electrons. Figure 5 (c) shows V S R-ZIS@Au-0.4, VS R-ZIS MFs, V S P-ZIS MFs, V S Transient photocurrent response curve of P-ZIS@Au-0.4 (λ > 420 nm), it can be seen that V S R-ZIS MFs is higher than V S The photocurrent intensity of P-ZIS MFs is high, indicating that V S As an electron trap, it can inhibit the separation of electron-hole pairs. V S The photocurrent intensity of R-ZIS@Au-0.4 is higher than V S P-ZIS@Au-0.4, indicating that a lower SHB is beneficial to the separation and transfer of photo-generated carriers. Figure 5 (d) is V S R-ZIS@Au-0.4, V S R-ZIS MFs, V S P-ZIS MFs, V S Electrochemical impedance spectroscopy of P-ZIS@Au-0.4 reveals that V S P-ZIS@Au-0.4 has the smallest resistance and the fastest rate of charge transfer from the bulk to the surface. Figure 5 (e) is V S R-ZIS@Au-0.4, V S R-ZIS MFs, V S P-ZIS MFs, V S Photoluminescence spectra of P-ZIS@Au-0.4 indicate that V S The charge transfer of R-ZIS@Au-0.4 is the most effective, thus promoting more photo-generated carriers to participate in CO2 photoreduction. Figure 5 (f) is V S R-ZIS@Au-0.4 V S R-ZIS MFs, V S P-ZIS MFs, V S Time-resolved fluorescence spectra of P-ZIS@Au-0.4 prove that V S R-ZIS@Au-0.4 improves the separation efficiency of photo-generated electrons and holes due to the presence of abundant Vs.

[0061] Figure 6 (a) is V S R-ZIS MFs, V S P-ZIS MFs, V S P-ZIS@Au-0.4, V S CO2 adsorption isotherm diagrams of R-ZIS@Au-0.4 show that compared with V S R-ZIS MFs, VS The CO2 adsorption capacity of R-ZIS@Au-0.4 is significantly enhanced (11.5 cm 3 / g), which is beneficial to CO2 reduction. Figure 6 (b) is the CO2 temperature-programmed desorption curve of V S R-ZIS@Au-0.4, V S R-ZIS MFs, and V S P-ZIS MFs. In the desorption temperature range of 400 - 680 °C, the peak position of V S R-ZIS@Au-0.4 is shifted compared to V S R-ZIS MFs and V S P-ZIS MFs, and a new peak appears, indicating that its surface is more prone to desorb *CO than V S R-ZIS MFs and V S P-ZIS MFs. Figure 6 (c) is the in-situ diffuse reflectance Fourier transform infrared spectrum of the photocatalytic CO2 reduction of V S R-ZIS@Au-0.4. As the irradiation time increases, the peak intensity representing the intermediate formed during the photocatalytic process gradually increases. For V S R-ZIS@Au-0.4, the characteristic peaks at 1368 cm -1 and 1433 cm -1 belong to the b-CO3 2- group and HCO3*, respectively. In addition, a new peak generated by COOH* appears at 1640 cm -1 , and COOH* is the key intermediate for the photoreduction of CO2 to CO.

[0062] Application Example 1

[0063] Six products obtained from the examples and comparative examples: V S R-ZIS@Au-0.2, V S R-ZIS@Au-0.4, V S R-ZIS@Au-0.6, V S P-ZIS@Au-0.4, V S R-ZIS MFs, and V S P-ZIS MFs. Specifically: Place 50 mg of the photocatalyst on the reactor, with an area of 4.2 cm 2A 300 W xenon lamp was used as the light source for the photocatalytic reaction. Before irradiation, the reactor was evacuated using a vacuum pump, and then high-purity CO2 gas was introduced into the reaction device to reach ambient pressure. 0.4 mL of deionized water was injected into the reaction flask. The prepared photocatalyst was equilibrated in a CO2 atmosphere for several hours. The temperature of the reaction system was maintained at 25 °C through circulating cooling water. During irradiation, 0.5 mL of gas was withdrawn from the reaction flask every hour and subjected to subsequent analysis using a gas chromatograph (GC9790 IIA, Fuli Analytical Instruments Co., Ltd., Zhejiang, China), which was equipped with FID and TCD detectors.

[0064] Figure 4 (a), Figure 4 (b) is V S R-ZIS@Au-0.2, V S R-ZIS@Au-0.4, V S R-ZIS@Au-0.6, V S R-ZISMFs, V S P-ZIS MFs, V S Photocatalytic CO2 reduction performance test diagrams of P-ZIS@Au-0.4, where V S R-ZIS@Au-0.4 has the optimal photocatalytic performance for reducing CO2 to CO (CO yield is 32.59 μmol g -1 ), and the selectivity is close to 100%. Figure 4 (c) is V S Photocatalytic CO2 reduction cycle test diagram of R-ZIS@Au-0.4, indicating that V S R-ZIS@Au-0.4 has excellent cycle stability; Figure 4 (d) is V S Photocatalytic CO2 reduction performance test diagrams of R-ZIS@Au-0.4 under different conditions, illustrating that V S The CO2 photoreduction reaction in R-ZIS@Au-0.4 is driven by light in the presence of the photocatalyst, and the carbon source of the product only comes from the injected CO2.

[0065] Although the description of the present invention has been quite detailed and several of the described embodiments have been described in particular, it is not intended to be limited to any of these details or embodiments or any particular embodiment, but rather should be regarded as providing a broad interpretation of these claims in light of the prior art by reference to the appended claims, thereby effectively covering the intended scope of the present invention. In addition, the present invention has been described above in terms of embodiments foreseeable by the inventors for the purpose of providing a useful description, and those non-substantive modifications to the present invention that are not currently foreseeable may still represent equivalent modifications of the present invention.

Claims

1. A preparation method of a ZnIn2S4@Au hierarchical heterostructure photocatalyst rich in sulfur vacancies, characterized in that, It includes the following steps: Disperse ZnIn2S4 microflowers rich in sulfur vacancies in an ethanol aqueous solution, then add chloroauric acid solution to obtain a suspension, and finally irradiate the suspension under ultraviolet-visible light. After the irradiation is completed, centrifuge, wash, and dry to finally obtain a ZnIn2S4@Au hierarchical heterostructure photocatalyst rich in sulfur vacancies; The ZnIn2S4 microflowers rich in sulfur vacancies are obtained by the following steps: First, dissolve zinc chloride in water, then successively add indium chloride tetrahydrate and thioacetamide. After complete dissolution, carry out a hydrothermal reaction. After the reaction is completed, centrifuge, wash, and freeze-dry to obtain ZnIn2S4 microflowers rich in sulfur vacancies; The molar ratio of zinc chloride, indium chloride tetrahydrate, and thioacetamide is 1:2:8 - 12; The temperature of the hydrothermal reaction is 160 °C - 200 °C, and the reaction time is 12 h - 18 h.

2. The preparation method according to claim 1, characterized in that, The volume percentage of ethanol in the ethanol aqueous solution is 20% - 60%.

3. The preparation method according to claim 1, wherein The dosage ratio of ZnIn2S4 microflowers to chloroauric acid solution is 0.3 g:0.7 mL - 2.1 mL.

4. The preparation method according to claim 1, characterized in that, When irradiating under ultraviolet-visible light, the intensity of the xenon lamp is 300 W, and the irradiation time is 2 h - 6 h.

5. The preparation method according to claim 1, characterized in that, The molar ratio of zinc chloride, indium chloride tetrahydrate, and thioacetamide is 1:2:

8.

6. A ZnIn2S4@Au hierarchical heterostructure photocatalyst rich in sulfur vacancies, characterized in that, Prepared by the preparation method described in any one of claims 1 - 5.

7. Application of the ZnIn2S4@Au hierarchical heterostructure photocatalyst rich in sulfur vacancies described in claim 6 in catalyzing CO2 reduction.

Images