H-ZISv / Au-Ag HAPs composite material and preparation method and application thereof

Abstract

The invention belongs to the field of composite material preparation, discloses an H-ZISv / Au-Ag HAPs composite material as well as a preparation method and application thereof, and solves the problem of poor photocatalytic hydrogen evolution performance of an existing photocatalyst. The H-ZISv / Au-Ag HAPs composite material is formed by loading hollow Au-Ag alloy nano particles on a hollow ZnIn2S4 nano cage containing sulfur vacancies, and the H-ZISv / Au-Ag HAPs composite material is a novel double-hollow plasma Schottky heterojunction photocatalyst. The material promotes the generation of a large amount of current carriers through the cooperation of a multi-light scattering / reflection effect and directional charge transfer; and the material has efficient hot electron excitation and excellent photothermal conversion performance. Through the synergistic effect generated by the optimized Schottky junction, plasma near-field enhancement and double-cavity constraint, the photo-thermal assisted photoelectrochemical reaction is improved. The catalyst has a hydrogen generation rate of 16 mmol g <-1 > h <-1 > and excellent stability under the conditions of AM 1.5 G illumination and 25 DEG C.

Description

Technical Field

[0001] This invention relates to the field of composite material preparation, and particularly to a photocatalytic material. Background Technology

[0002] Faced with the escalating global energy shortage and the vicious cycle between fossil resource depletion and environmental degradation, finding renewable and environmentally compatible new energy supply systems has become an urgent priority. Photocatalytic hydrogen production technology has shown unique potential, opening new pathways for clean energy. However, the application of intrinsic semiconductors is limited by their weak sunlight capture capacity, easy recombination of photogenerated carriers, and insufficient charge migration driving force. To overcome these challenges, researchers have employed various modification strategies to improve their performance, including morphology modification, doping, defect engineering, and the construction of heterojunctions. Despite some progress in materials modification, the utilization rate of light energy remains unsatisfactory.

[0003] Patent CN116651470A discloses the preparation and application of a CdMoO4 / ZnIn2S4 nanosphere catalyst with photocatalytic properties. The method involves dissolving CdMoO4 nanospheres in deionized water, adjusting the pH, then adding thioacetamide, zinc chloride, and indium chloride. After reacting in an oil bath, the mixture is centrifuged, washed, and dried to obtain the CdMoO4 / ZnIn2S4 nanosphere catalyst with photocatalytic properties. While this approach improves photocatalytic performance to some extent, its performance remains limited; for example, the photocatalytic hydrogen production from water splitting is only 7634.67 μmol / g. -1 h -1 Therefore, it is crucial to propose a novel composite material structure to improve photocatalytic performance. Summary of the Invention

[0004] To address the technical problem of poor photocatalytic hydrogen production performance of existing materials, this invention proposes an H-ZISv / Au-Ag HAPs composite material, its preparation method, and its application.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A novel H-ZISv / Au-Ag HAPs composite material is proposed, formed by loading hollow Au-Ag alloy nanoparticles onto hollow ZnIn2S4 nanocages containing sulfur vacancies. The Au-Ag composite exhibits both high-energy "hot electrons" (participating in the reduction reaction) and thermal energy generated by non-radiative relaxation, due to the LSPR effect. This generated heat is confined within the double-hollow structure, and the localized heating further enhances the plasmon oscillation efficiency and carrier generation rate of the Au-Ag composite.

[0007] The preparation method of the above-mentioned H-ZISv / Au-Ag HAPs composite material includes the following steps:

[0008] (1) Dissolve ZIF-8 powder in tannic acid aqueous solution and then etch to obtain YS-ZIF-8 powder;

[0009] (2) ZnCl2, indium chloride tetrahydrate and thioacetamide were added to a mixed solvent of ethanol and glycerol to obtain solution A; then solution A was added to YS-ZIF-8 ethanol solution and ZnIn2S4 nanocages, i.e. H-ZISv, were obtained by hydrothermal reaction.

[0010] (3) Heat the HAuCl4 solution to boiling, then add the trisodium citrate dihydrate solution and the Ag NPs aqueous dispersion, and stir for 4-6 min; then immerse the reaction system in an ice-water bath, and obtain Au-Ag HAPs after cooling and centrifugation; wherein, based on the difference in standard reduction potential between metals, the substitution and structural recombination of metal elements are achieved through spontaneous redox reactions. 3+ Its oxidizing power is much stronger than that of Ag. + Au 3+ On the AgNPs surface, they are reduced to Au atoms. Due to the Kirkendall effect, cavities are eventually formed.

[0011] (4) Disperse the Au-Ag HAPs obtained in step (3) in water, add the ZnIn2S4 nanocages obtained in step (2), and after stirring, ultrasonic mixing and drying, obtain the H-ZISv / Au-Ag HAPs composite material.

[0012] The preparation steps of ZIF-8 powder in step (1) above are as follows: 2-methylimidazole and zinc acetate are dissolved in deionized water to obtain a mixed solution; then the zinc acetate solution is slowly poured into the mixed solution placed in a magnetic stirrer, and after vigorous stirring, it is centrifuged. After pouring off the supernatant, it is washed several times with a large amount of anhydrous methanol to remove unreacted imidazole ligands. The resulting white powder is dried in a vacuum oven to obtain ZIF-8.

[0013] Furthermore, in step (1) above, the concentration of tannic acid aqueous solution is 3-6 g / L, and 0.5-2 g of ZIF-8 powder is added to each L of tannic acid aqueous solution; the etching time is 20-50 min.

[0014] In step (2) above, the molar ratio of ZnCl2, indium chloride tetrahydrate and thioacetamide in solution A is 0.5-1.5:1:2, the concentration of ZnCl2 in solution A is 0.015-0.030 mol / L, the concentration of YS-ZIF-8 ethanol solution is 0.68-0.80 g / mL, the volume ratio of solution A to YS-ZIF-8 ethanol solution is 1-2:1, the hydrothermal reaction temperature is 170-190℃, and the time is 1.5-2.5 h.

[0015] In step (3) above, the concentration of HAuCl4 solution is 30-60 μM, the concentration of trisodium citrate dihydrate solution is 0.3-0.6 wt%, and the concentration of Ag NPs aqueous dispersion is 0.05-0.15 g / mL.

[0016] Furthermore, in step (3) above, the volume ratio of HAuCl4 solution, trisodium citrate dihydrate solution and Ag NPs aqueous dispersion is 60-70:1:1.3.

[0017] In step (4) above, the Au-Ag HAPs loading is 13-14 wt%.

[0018] The above-mentioned H-ZISv / Au-Ag HAPs composite material is used in photocatalytic hydrogen production.

[0019] The beneficial effects of this invention are:

[0020] (1) This invention proposes a novel double-hollow plasma Schottky heterojunction photocatalyst (H-ZISv / Au-Ag HAPs). Hollow ZnIn2S4 nanocages rich in sulfur vacancies (H-ZISv) are synthesized by template-confined epitaxy, and then hollow Au-Ag alloy nanoparticles (Au-Ag HAPs) are loaded by impregnation. This hollow nanoreactor promotes the generation of a large number of charge carriers through synergistic multi-light scattering / reflection effect and directional charge transfer.

[0021] (2) The H-ZISv / Au-Ag HAPs of the present invention achieve efficient thermionic excitation and excellent photothermal conversion through strong interfacial coupling mediated by sulfur vacancies, near-infrared absorption broadening achieved by local surface plasmon resonance (LSPR) of Au-Ag HAPs, and strong local electromagnetic field enhancement ("hot spot").

[0022] (3) The synergistic effect of the optimized Schottky junction, plasma near-field enhancement, and dual-cavity confinement in the composite material of this invention greatly improves the performance of photothermal-assisted photoelectrochemical reaction (PHE). This catalyst achieved a yield as high as 16 mmol g under AM 1.5G illumination and 25°C. -1 h-1 It exhibits a high hydrogen generation rate and excellent stability (over 750 minutes), and also has measurable near-infrared activity at 800 nm. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a flowchart illustrating the preparation process of the H-ZISv / Au-Ag HAPs composite material of the present invention.

[0025] Figure 2 The images are scanning electron microscope (SEM) and TEM images; (a) is the SEM image of YS-ZIF-8 and (b) is the TEM image; (c) is the TEM image and SEM image of H-ZISv and (d); (e) and (f) are the TEM image and HRTEM image of Au-Ag HAPs, respectively; (g), (h) and (i) are the TEM image, HRTEM image, SEM image and corresponding EDS elemental mapping of H-ZISv / Au-Ag HAPs prepared in Example 1, respectively; (j) is the HAADF-STEM and EDS elemental mapping of Au-Ag HAPs.

[0026] Figure 3 The following are the characterization spectra of each material; (a) is the XRD spectrum; (b) is the electron spin resonance (ESR) spectrum; (c) and (d) are the specific surface area and pore size distribution maps, respectively; (e) is the UV-Vis diffuse reflectance spectrum; and (f) is the absorption spectrum obtained by the Kubelka-Munk transform function.

[0027] Figure 4 The XPS spectra of the materials prepared in Example 1 and Comparative Examples 1-3 are shown below; where (a) is the total XPS spectrum and (bf) are the high-resolution XPS spectra of Zn 2p, In 3d, S 2p, Au 4f and Ag 3d, respectively.

[0028] Figure 5 The charge transfer kinetics and photothermal effects of the materials prepared in Examples 1 and Comparative Examples 1-3 are analyzed; wherein, (a) is the transient photocurrent response diagram; (b) is the electrochemical impedance spectroscopy diagram; (c) is the photoluminescence (PL) spectrum; (d) is the time-resolved fluorescence decay spectrum; and (ef) are the results of the photoluminescence at AM 1.5G with a light intensity of 150 mW / cm². 2Infrared thermal images of the surface temperatures of H-ZISv, H-ZISv / Au, H-ZISv / Ag and H-ZISv / Au-Ag HAPs before irradiation (top) and after stabilization (bottom) under irradiation.

[0029] Figure 6 The graphs show the photothermal catalytic hydrogen production performance of each material; (a) shows the total hydrogen production of H-ZISv and H-ZISv / Au-Ag (H-ZISv / Au-Ag HAPs) prepared in Example 1 at different temperatures within 2.5 h; (b) shows the average hydrogen evolution rate of H-ZISv, H-ZISv / Au, and H-ZISv / Ag at different temperatures; (c) shows the photocatalytic hydrogen evolution rate of H-ZISv / Au-Ag (H-ZISv / Au-Ag HAPs) prepared in Example 1 at different temperatures; and (d) shows the cycle stability test of photocatalytic hydrogen production of H-ZISv / Au-Ag (H-ZISv / Au-Ag HAPs) prepared in Example 1.

[0030] Figure 7 This is a schematic diagram of band structure analysis and photocatalytic mechanism; (a) and (b) are Mott-Schottky (MS) diagrams of H-ZISv and H-ZISv / Au-Ag, respectively; (c) and (d) are the work functions of the H-ZISv surface and the Au-Ag surface, respectively; (e) is the photocatalytic mechanism of H-ZISv / Au-Ag.

[0031] Figure 8 The spatial distribution of the electric field is simulated for H-ZISv(a) and H-ZISv / Au-Ag(b). Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] The specific materials used in this invention are as follows: silver nitrate (AgNO3, 99.99%), sodium borohydride (NaBH4, 98%), trisodium citrate dihydrate (C6H5Na3O7, 98%), ethylene glycol (C2H6O2, 98%), zinc chloride (ZnCl2, 98%), indium chloride tetrahydrate (InCl3•4H2O), thioacetamide (C2H5NS, TAA, 98%), and glycerol (C3H8O3, 99%). All of these reagents were purchased from Shanghai Aladdin Chemical Reagent Co., Ltd. Anhydrous ethanol (C2H5OH, 99.9%) was purchased from Sinopharm Group Chemical Reagent Co., Ltd., tetrachloroauric acid tetrahydrate (HAuCl4•4H2O) was purchased from Haohong Biomedical Technology Co., Ltd., and 2-methylimidazole (2-MI), tannic acid (TA), and zinc acetate. All of these chemical reagents were at least analytical grade and used without further purification. Furthermore, deionized water (DI) was used throughout the study.

[0034] The synthesis method of ZIF-8 in the following examples is as follows: 15 g of 2-MI and 4.2 g of (CH3COO)2Zn were weighed and dissolved in 100 mL of deionized water and sonicated to obtain an imidazole solution; then, a zinc acetate solution (0.15 g / mL, 100 mL) was slowly poured into the imidazole solution placed on a magnetic stirrer, and the mixture was stirred vigorously for 2 h (25℃) before centrifugation. After pouring off the supernatant, the mixture was washed several times with a large amount of anhydrous methanol to remove unreacted imidazole ligands. The resulting white powder was dried in a vacuum oven to obtain ZIF-8.

[0035] The preparation method of Ag NPs is as follows:

[0036] The preparation of Ag nanoparticles mainly involves a seed-mediated method. First, Ag seeds are prepared by reducing AgNO3 with NaBH4, followed by further growth of the Ag seeds. Specifically, 2 mL of a 1.1% trisodium citrate dihydrate solution is added to 75 mL of dimethyl ether (DI) and boiled for 20 min. Then, 10 mL of Ag seeds are rapidly added, and while maintaining vigorous stirring, 1.5 mL of a 1% AgNO3 solution is quickly poured in and boiling continues for 1 h. Next, 2 mL of a 1.1% trisodium citrate dihydrate (SC) solution and 1.7 mL of a 1% AgNO3 solution are added, and boiling continues for another 1 h, followed by natural cooling. Ag nanoparticles are obtained by centrifugation at 10,000 rpm.

[0037] The preparation method of Au NPs is as follows:

[0038] Au nanoparticles were prepared using the sodium citrate method. 1 mL of 0.01 M HAuCl4·4H2O solution was added to 40 mL of DI, and the mixture was then heated to boiling. Simultaneously, a 1% fresh sodium citrate solution was prepared. After the chloroauric acid solution boiled, 1.6 mL of the sodium citrate solution was quickly added to it. The reaction continued, during which the solution color gradually changed from its initial state to a wine-red color. After approximately 20 minutes, when the solution was completely wine-red, heating was stopped, and the reaction solution was allowed to cool naturally. Then, after centrifugation at 10,000 rpm for 5 minutes, the Au nanoparticles (Au NPs) were separated from the reaction solution.

[0039] Example 1

[0040] The preparation method of the H-ZISv / Au-Ag HAPs composite material in this embodiment is shown in the flowchart below. Figure 1 As shown, the steps are as follows:

[0041] (1) Dissolve 160 mg of white powder ZIF-8 in tannic acid aqueous solution (160 mL, 5 g / L), then stir the mixture vigorously for 30 min, centrifuge to collect the product, wash it several times with anhydrous ethanol for later use, and then obtain YS-ZIF-8.

[0042] (2) Dissolve the YS-ZIF-8 prepared in step (1) in 14 mL of ethanol and sonicate for 7 min to form solution B (0.789 g / mL); dissolve ZnCl2 (54.4 mg), InCl3•4H2O (117.2 mg), and TAA (60 mg) in a mixed solvent consisting of 10 mL of ethanol and 6 mL of glycerol to form solution A; then quickly pour 16 mL of solution A into 14 mL of solution B and stir for 30 min to mix thoroughly. Then transfer the mixture to a stainless steel autoclave lined with polytetrafluoroethylene and keep it at 180 °C for 2 h. After that, wash it alternately with anhydrous ethanol and DI, and dry it overnight in an oven at 80 °C. The resulting sample is named H-ZISv.

[0043] (3) Mix 20 μL of 0.01 M tetrachloroauric acid tetrahydrate solution with 4 mL of water and heat to boiling. Then, quickly inject 60 μL of 0.5% SC solution and 80 μL of Ag NPs aqueous dispersion (concentration 0.1 g / mL) and stir vigorously. The solution immediately turns blue. Continue stirring for 5 min while the solution is boiling. Then, quickly immerse the reaction system in an ice-water bath to cool the contents. After centrifugation at 10,000 rpm for 5 min, Au-Ag HAPs (HollowAlloy Particles) are separated from the reaction solution.

[0044] (4) Add 15 mg of H-ZISv obtained in step (2) to 24 mL of Au-Ag HNP dispersion (0.085 mg of Au-Ag HAPs dispersed in each mL of H2O) prepared in step (3) above, mix thoroughly by stirring and sonication, and then dry in a vacuum oven at 70°C to obtain H-ZISv / Au-Ag HAPs composite material, abbreviated as H-ZISv / Au-Ag (the loading of Au-Ag HAPs in the composite material is 12 wt%).

[0045] Comparative Example 1

[0046] The preparation method of the sulfur-vacant hollow ZnIn2S4 nanocages (H-ZISv) in this comparative example is the same as that in Example 1.

[0047] Comparative Example 2

[0048] The preparation method of H-ZISv / Ag in this comparative example is as follows:

[0049] (1) The preparation method of H-ZISv is the same as that of Comparative Example 1.

[0050] (2) Disperse 0.10 mg Ag NPs in 2 mL H2O to obtain Ag NPs dispersion; add 15 mg H-ZISv obtained in step (1) to the above 40 mL Ag NPs dispersion, mix thoroughly by stirring and sonication, and then dry in a vacuum oven at 70℃ to obtain H-ZISv / Ag composite material, abbreviated as H-ZISv / Ag.

[0051] Comparative Example 3

[0052] The preparation method of H-ZISv / Au in this comparative example is as follows:

[0053] (1) The preparation method of H-ZISv is the same as that of Comparative Example 1.

[0054] (2) 1.70 mg Au NPs were dispersed in 20 mL H2O to obtain Au NPs dispersion; 15 mg H-ZISv obtained in step (1) was added to the above 40 mL Au NPs dispersion, and the mixture was thoroughly mixed by stirring and sonication. Then it was dried in a vacuum oven at 70℃ to obtain H-ZISv / Au composite material, abbreviated as H-ZISv / Au.

[0055] Example 2

[0056] The preparation method of the H-ZISv / Au-Ag HAPs composite material in this embodiment is shown in the flowchart below. Figure 1 As shown, the steps are as follows:

[0057] (1) Dissolve 80 mg of white powder ZIF-8 in tannic acid aqueous solution (160 mL, 3 g / L), then stir the mixture vigorously for 50 min, centrifuge to collect the product, wash it several times with anhydrous ethanol for later use, and then obtain YS-ZIF-8.

[0058] (2) Dissolve the YS-ZIF-8 prepared in step (1) in 14 mL of ethanol and sonicate for 7 min to form solution B (0.68 g / mL); dissolve ZnCl2 (27.2 mg), InCl3•4H2O (117.2 mg), and TAA (60 mg) in a mixed solvent consisting of 8 mL of ethanol and 5 mL of glycerol to form solution A; then quickly pour 12 mL of solution A into 12 mL of solution B and stir for 30 min to mix thoroughly. Then transfer the mixture to a stainless steel autoclave lined with polytetrafluoroethylene and keep it at 170 °C for 2.5 h. After that, wash it alternately with anhydrous ethanol and DI, and dry it overnight in an oven at 80 °C. The resulting sample is named H-ZISv.

[0059] (3) Mix 10 μL of 0.01 M tetrachloroauric acid tetrahydrate solution with 3.6 mL of water and heat to boiling. Then, quickly add 60 μL of 0.6% SC solution and 80 μL of Ag NPs aqueous dispersion (concentration 0.15 g / mL) and stir vigorously. The solution immediately turns blue. Continue stirring for 5 min while the solution is boiling. Then, quickly immerse the reaction system in an ice-water bath to cool the contents. After centrifugation at 10,000 rpm for 5 min, Au-Ag HAPs (HollowAlloy Particles) are separated from the reaction solution.

[0060] (4) Add the 13 mg H-ZISv obtained in step (2) to the 24 mL Au-Ag HNP dispersion (0.085 mg Au-Ag HAPs dispersed in each mL of H2O) prepared in step (3) above, mix thoroughly by stirring and sonication, and then dry in a vacuum oven at 70°C to obtain the H-ZISv / Au-Ag HAPs composite material, abbreviated as H-ZISv / Au-Ag (the Au-Ag HAPs loading in the composite material is 13.5 wt%).

[0061] Example 3

[0062] The preparation method of the H-ZISv / Au-Ag HAPs composite material in this embodiment is shown in the flowchart below. Figure 1 As shown, the steps are as follows:

[0063] (1) Dissolve 320 mg of white powder ZIF-8 in tannic acid aqueous solution (160 mL, 6 g / L), then stir the mixture vigorously for 20 min, centrifuge to collect the product, wash it several times with anhydrous ethanol for later use, and then obtain YS-ZIF-8.

[0064] (2) Dissolve the YS-ZIF-8 prepared in step (1) in 14 mL of ethanol and sonicate for 7 min to form solution B (0.80 g / mL); dissolve ZnCl2 (81.6 mg), InCl3•4H2O (117.2 mg), and TAA (60 mg) in a mixed solvent consisting of 12 mL of ethanol and 8 mL of glycerol to form solution A. Then, quickly pour 16 mL of solution A into 8 mL of solution B and stir for 30 min to mix thoroughly. Then transfer the mixture to a stainless steel autoclave lined with polytetrafluoroethylene and keep it at 190 °C for 1.5 h. After that, wash it alternately with anhydrous ethanol and DI, and dry it overnight in an oven at 80 °C. The resulting sample is named H-ZISv.

[0065] (3) Mix 25 μL of 0.01 M tetrachloroauric acid tetrahydrate solution with 4.2 mL of water and heat to boiling. Then quickly inject 60 μL of 0.3% SC solution and 80 μL of Ag NPs aqueous dispersion (concentration of 0.05 g / mL) and stir vigorously. The solution immediately turns blue. Continue stirring for 5 min while the solution is boiling. Then quickly immerse the reaction system in an ice-water bath to cool the contents of the system. After centrifugation at 10,000 rpm for 5 min, Au-Ag HAPs (HollowAlloy Particles) are separated from the reaction solution.

[0066] (4) Add 12.5 mg H-ZISv obtained in step (2) to 24 mL Au-AgHNP dispersion (0.085 mg Au-Ag HAPs dispersed in each mL H2O) prepared in step (3) above, mix thoroughly by stirring and sonication, and then dry in a vacuum oven at 70℃ to obtain H-ZISv / Au-Ag HAPs composite material, abbreviated as H-ZISv / Au-Ag (the loading of Au-Ag HAPs in the composite material is 14 wt%).

[0067] Implementation Results Example

[0068] The microstructure and morphology, elemental composition, charge transfer kinetics, photothermal effect, and photothermal catalytic performance of the materials prepared in Example 1 and Comparative Examples 1-3 were tested and analyzed. Specific results are as follows:

[0069] (1) Crystal structure and morphology analysis

[0070] The catalyst was analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). TEM and SEM images visually demonstrated the evolution of the hollow structure and the co-catalyst and hollow structure assembly. XRD patterns confirmed the formation of the metal-organic framework ZIF-8 with a microporous structure. Figure 3 a). After TA wet etching, the surface of the ZIF-8 polyhedron became rough, but the size (average size 600 nm) and morphology of the original dodecahedral ZIF-8 remained unchanged. Figure 2 a) Combining Figure 2 TEM results for b indicate that the yolk shell structure has been successfully prepared. Subsequently, TAA and In... 3+ The epitaxial growth is constrained within its core-shell interlayer and bonded with framework ions, thereby forming a 3D hollow nanostructure assembled from 2D ultrathin nanosheets. SEM and TEM images of H-ZISv are shown below. Figure 2 c and Figure 2 As shown in Figure d, it can be clearly seen that ZnIn2S4 nanosheets are uniformly covered on YS-ZIF-8, maintaining the polyhedral shape of ZIF-8. TEM images also confirm the formation of the hollow structure. The Au-Ag HAPs obtained from the reaction maintain the same size (average particle size of 25±5 nm) and crystallinity as Ag NPs. Figure 2 e). The structure of Au-Ag HAPs was further investigated using TEM and HRTEM. Figure 2 HRTEM of f verified the hollow structure of Au-Ag. Further observation of the lattice fringes of Au-Ag HAPs showed that lattice fringes with lattice spacing of 0.235 nm and 0.204 nm were indexed to the (111) and (222) planes of Au-Ag. Figure 2 HADDF-STEM analysis of the sample showed that Au and Ag were uniformly distributed in the Au-Ag alloy, further confirming the successful preparation of Au-Ag HAPs at an Au:Ag atomic ratio of 6:4.

[0071] Figure 2 TEM images of g show Au-Ag HAPs uniformly dispersed on the surface of H-ZIS, and HRTEM ( Figure 2 h) shows obvious lattice fringes and interplanar spacing, which are attributed to the (200) and (111) planes of Au-Ag HAPs and the (102) plane of ZnIn2S4. Figure 2 EDS analysis of i showed uniform dispersion of Au and Ag elements, demonstrating the random distribution of Au-Ag around H-ZISv. Since Au-Ag HAPs form metal-carboxylate bonds with residual citrate ions, this favors interaction with Zn exposed at S vacancies.2+ / In 3+ Coordination, this dense contact ensures short-distance migration of photogenerated carriers.

[0072] The phase composition of the template agent and the ZnIn2S4 derived catalyst was measured and analyzed by X-ray diffraction. Figure 3 a) After TA etching, all characteristic peaks of ZIF-8 were retained, but the peak intensities were weakened. In hexagonal ZnIn2S4 (JCPDS#65-2023), the (006), (102), and (110) planes of H-ZISv, H-ZISv / Au, and H-ZISv / Au-Ag showed obvious characteristic peaks at 21.58°, 27.69°, and 47.16°, respectively. It is worth noting that after the addition of Au-Ag HAPs, the diffraction peaks of H-ZISv remained unchanged, indicating that the metal particles did not affect its crystal structure. Diffraction peaks belonging to the (111), (200), (220), and (311) crystal planes of Au and Ag were observed at 38.3°, 44.4°, 64.7°, and 77.3°. The performance of the prepared catalyst was evaluated by BET gas adsorption measurement, in which the S of H-ZISv was measured. BET It is 66.226 m 2 / g, confirming that hollow morphology modulation leads to a larger specific surface area ( Figure 3 c). Since the particle size of Au and Ag is much larger than that of H-ZISv, the microporous channels have not changed the crystal framework of H-ZISv, so it still retains its 2 nm microporous structure. Figure 3 d), so when Au-Ag HAPs with a cavity structure are highly uniformly dispersed on ZnIn2S4 with another cavity structure, the dual-cavity synergistic confinement greatly increases the specific surface area of ​​H-ZISv. The heterogeneous photocatalyst with a large specific surface area significantly improves photocatalytic performance by providing high-density active sites and promoting the redox transport of photogenerated carriers.

[0073] (2) Elemental composition analysis and carrier migration

[0074] To investigate the elemental surface composition and chemical state of H-ZISv / Au-Ag catalysts and to confirm the charge transfer mechanism, X-ray photoelectron spectroscopy (XPS) studies were performed on H-ZISv, H-ZISv / Au, H-ZISv / Ag, and H-ZISv / Au-Ag. Figure 4 XPS spectra of Zn₂P confirmed the presence of all elements. All samples were pure and free of impurities, and C 1s with a binding energy of 284.8 eV was used to calibrate all remaining elements. The two convolution peaks at 1021.96 and 1044.96 eV in the high-resolution Zn₂P XPS spectrum correspond to Zn₂P₂. 3 / 2 and Zn 2p1 / 2 ( Figure 4 b). Meanwhile, in H-ZISv, In 3d 5 / 2 and In 3d 3 / 2 The binding energies are located at 444.85 eV and 452.37 eV, respectively, shifting to higher binding energies by approximately 0.16 eV after the formation of the Schottky junction. Figure 4 c) further confirms the electron transfer to Au or Ag. Furthermore, the peaks at 161.54 eV and 162.75 eV in the S 2p spectrum are attributed to S 2p. 3 / 2 and S 2p 1 / 2 The deconvolution peak indicates that S exists in all materials. 2- ( Figure 4 d). In various spectra, it was observed that after coupling with Au-Ag, the binding energies of Zn 2p, In 3d, and S 2p showed a significant negative shift relative to the binding energies of elements in H-ZISv, indicating a strong interfacial interaction only between Au-Ag HAPs and H-ZISv. This further strongly confirms the transfer of more electrons to Au-Ag HAPs. In the Au 4f spectrum (… Figure 4 In e), the two peaks at 87.57 and 83.85 eV correspond to Au 4f. 7 / 2 and 4f 5 / 2 This revealed the metallic state of Au NPs on the catalyst surface. Figure 4 e and Figure 4 The f-values ​​in H-ZISv / Au-Ag show that Au 4f (-0.05 eV) and Ag 3d (-0.05 eV) and the binding energy both shift to lower values, indicating that photogenerated electrons accumulate at the Au-Ag site for H2 reduction. Meanwhile, the Zn 2p binding energy shifts to a higher position, confirming that holes accumulate at H-ZISv.

[0075] To investigate the origin of this strong interfacial interaction, EPR was used to detect spin signal peaks generated by unpaired electrons, and lattice defects (S vacancies) were identified using EPR spectra. Figure 3 As shown in b, there are almost no S vacancies in the template agent ZIF-8. A strong signal was observed in H-ZISv at g=2.002, indicating that H was released by TA during the hollowing process. + The coordinate bonds of ZIF-8 were gradually disrupted, a phenomenon that can be attributed to... Figure 3This is confirmed by the weakening XRD diffraction peak intensity in YS-ZIF-8. Compared to H-ZISv, H-ZISv / Au, H-ZISv / Ag, and H-ZISv / Au-Ag exhibit relatively weaker EPR responses. This phenomenon is attributed to the bonding interaction between the metal atoms in Au-Ag and the coordinated unsaturated atoms within the defect-state ZnIn2S4 framework. This interaction reduces the number of unpaired electrons, thereby lowering the defect concentration in the Schottky junction.

[0076] To verify the ultra-wideband light absorption characteristics exhibited by the hollow structure, the light-trapping properties of the sample were studied using ultraviolet-visible diffuse reflectance spectroscopy (DRS). Figure 3 As shown in Figure e, H-ZISv exhibits weak visible light absorption at approximately 490 nm, while no absorption was observed in the NIR region. Furthermore, H-ZISv / Au and H-ZISv / Ag not only enhance the light absorption intensity but also broaden the absorption band to both the visible and NIR regions. This is attributed to their respective LSPR effects and the ability of their cavity structure to further enhance light absorption through multiple internal light reflections. The overlapping absorption of Au and Ag results in a stronger LSPR characteristic peak between 500 nm and 600 nm, more fully demonstrating their ability to excite free electrons into hot electrons.

[0077] To gain a deeper understanding of the electronic structure of the sample, the valence band (EVB) and conduction band (ECB) values ​​were calculated using the Kubelka-Munk formula and Tauc curves, as follows: Figure 3 As shown in f, the band gap of the H-ZISv-based catalyst is 2.72 eV, which confirms that the construction of the Schottky junction does not affect the electronic structure of the intrinsic semiconductor. The flat band potential (Efb) was analyzed by Mott-Schottky (MS) curve analysis, and the positive slope of the linear curve confirms that it is an n-type semiconductor. Figure 7 The flat band potential of H-ZISv relative to Ag / AgCl was measured to be -0.95 eV, which, after conversion, yielded a potential of -0.75 eV relative to the standard hydrogen electrode (NHE). Specifically, for an n-type semiconductor, Efb is 0.1 eV higher than ECB, therefore the calculated ECB of H-ZISv is -0.85 eV. Further combining this with the formula ECB = EVB - Eg, the corresponding EVB is 1.87 eV. Based on these results, the band structure and charge transfer path were plotted, and the PHE mechanism was proposed.

[0078] Figure 7The above explains the photothermal-assisted photocatalytic hydrogen evolution mechanism of the H-ZISv / Au-Ag composite material. When Au-Ag HAPs and H-ZISv come into contact, considering that the work function of H-ZISv is smaller than that of Au-Ag HAPs, electrons from H-ZISv diffuse to the surface of Au-Ag HAPs, causing the energy bands in H-ZISv to bend upwards and establish a Fermi level equilibrium between H-ZISv and Au-Ag HAPs, thus forming a Schottky barrier, which significantly hinders the flow of electrons from Au-Ag HAPs to H-ZISv. As a result, under AM 1.5G irradiation, more excited photogenerated electrons migrate rapidly along the nanosheets on the hollow shell to the hollow Au-Ag. The electrons migrating to Au-Ag HAPs are directly excited into hot electrons through the LSPR effect, and together with the transferred photogenerated electrons from H-ZISv, they participate in the photocatalytic water splitting process to produce hydrogen. During the construction of hollow nanocages, the precise introduction of S vacancies effectively enhanced the interfacial coupling with Au-Ag HAPs. This strong interfacial coupling not only promoted the directional migration of photogenerated electrons to Au-Ag HAPs, but also the continuous replenishment of intrinsically excited superthermal electrons effectively prolonged their relaxation time. Therefore, the photothermal catalytic hydrogen production was further optimized through the photothermal effect enhanced by phonon-phonon scattering.

[0079] (3) Finite element simulation analysis

[0080] The "hot spot" effect of H-ZISv / Au-Ag under 420 nm photoexcitation enhanced by local electric field was studied using FEM simulation. Figure 8 a shows the weak field strength generated at the H-ZISv-water interface under specific photoexcitation. When Au-Ag HAPs are loaded, the local electromagnetic field density near Au-Ag is increased. This is due to the presence of numerous plasma "hot spots" at the interface between Au-Ag and H-ZISv, which amplifies the local electromagnetic field strength. Figure 8 (b) Simulation results show that the electromagnetic field strengths of H-ZISv and H-ZISv / Au-Ag are 4.02 and 13.4, respectively, confirming that the electromagnetic field strength in the local "hot spot" region can be increased by at least one order of magnitude compared to far-field excitation. Furthermore, this significant electromagnetic field enhancement effect can greatly improve the carrier generation efficiency in this region, as the formation rate is proportional to the square of the electric field strength. These simulation results indicate that after Au-Ag excitation, the LSPR effect can significantly enhance the transfer rate of hot electrons at the Schottky interface, thereby effectively increasing the charge accumulation concentration within the heterojunction system and thus greatly optimizing its catalytic performance. This is consistent with the UV-Vis DRS characterization and provides a theoretical basis for the photothermal effect caused by non-radiative decay.

[0081] (4) Analysis of charge transfer kinetics and photothermal effect

[0082] Analyzing the charge transfer kinetics of catalysts helps elucidate the mechanisms underlying catalyst performance enhancement. For example... Figure 5 Transient photocurrent response analysis showed that H-ZISv / Au-Ag exhibited the highest photocurrent density, with an average photocurrent value of 3.82 μA cm⁻¹. 2 It is H-ZISv (0.63 μA cm⁻¹) -2 The capacitance is 6.06 times that of the original catalyst, indicating a more efficient charge separation capability. Electrochemical impedance spectroscopy (EIS) shows that the arc radius of H-ZISv / Au-Ag is smaller, indicating a lower interfacial charge transfer resistance compared to other catalysts. Figure 5 b). This is because the formed Schottky barrier hinders electron reflow and the near-field enhancement of Au-Ag HAPs induced by LSPR promotes carrier separation and significantly reduces electron recombination efficiency. Figure 5 c shows the photoluminescence (PL) spectra of each catalyst. H-ZISv shows the strongest luminescence signal, which is because a single sulfur vacancy is insufficient to suppress the rapid electron-hole recombination. H-ZISv / Au-Ag exhibits the most significant PL quenching, indicating that the Schottky barrier formed with Au-Ag HAPs, which have enhanced LSPR effects, plays a positive role in electron trapping and accelerated carrier separation. Simultaneously, time-resolved fluorescence decay spectra (TRPL) were measured to determine the lifetime of photogenerated electron-hole pairs, and the carrier lifetime was calculated using a double exponential decay curve as a model. Figure 5 d), where τ1 corresponds to the hot electron process formed by heating the metal lattice through electron-phonon scattering, and τ2 corresponds to the phonon-phonon scattering process formed by dissipating thermal energy from the metal lattice to the surrounding medium (interfacial heat dissipation). The average fluorescence lifetimes (Ave.τ) of H-ZISv / Au and H-ZISv / Ag are 9.99 ns and 10.13 ns, respectively, successfully extending the hot electron relaxation time and promoting the dissipation of lattice energy to the surrounding medium. The Ave.τ of H-ZISv / Au-Ag is longer than that of H-ZISv (Ave.τ = 1.96 ns), and the nonradiative decay transition rate is higher, which provides more intuitive evidence for the extended charge lifetime.

[0083] Photothermal effect is a crucial factor in improving PHE performance. During non-radiative decay, not all the hot electrons generated by LSPR participate in the chemical reaction. These unreacted hot electrons transfer energy to the metal lattice through electron-lattice collisions, inducing an ultrafast lattice temperature rise within a picosecond (ps) timescale. Therefore, infrared thermal imaging was used to monitor the surface temperature change of the catalyst powder, with a recording interval of 30 s. After 120 s of xenon lamp irradiation at room temperature, the data was collected... Figure 5 As shown in the figure, H-ZISv / Au and H-ZISv / Ag increased by approximately 22℃ and 27℃ respectively compared to H-ZISv (70.8℃), reaching or even exceeding the final stability temperature of H-ZISv in just 60 s. This indicates that the thermal confinement effect formed by the closed cavity of the composite material and the thermal accumulation effect generated by the LSPR mechanism are the main reasons for the enhanced photothermal effect. Au-Ag HAPs, a bimetallic plasma, further enhances the photothermal effect due to the multiple light refractions within its own cavity structure, which prolongs the light contact time and creates a stronger local electric field, resulting in a "hot spot" effect. This allows it to effectively generate a stronger plasmon effect, leading to a higher nonradiative decay rate. Therefore, Figure 5 h further verified the above conjecture, showing that the surface temperature of H-ZISv / Au-Ag showed a greater upward trend.

[0084] (5) Performance analysis of photothermal catalytic hydrogen production (PHE)

[0085] At AM 1.5G, the PHE (Protection of Health) capacity of 15 mg H-ZISv, H-ZISv / Au, H-ZISv / Ag, and H-ZISv / Au-Ag was evaluated using a 50 mL mixture of 0.2 mol / L Na₂SO₃ and Na₂S. The results clearly show a positive correlation between the PHE of the target catalyst and temperature, and temperature control can be achieved by adjusting the temperature of the circulating cooling water. Figure 6 As shown in Figure a, the effect of temperature on the performance of H-ZISv is negligible, and the performance of the photocatalysts supported by these three materials is superior to that of the pure materials. When the ambient temperature is 5℃ and the total time is 2.5 h, the hydrogen production of H-ZISv / Au-Ag is 11.9 mmol g. -1 It is 1.4 times that of H-ZISv, but this ratio increases to 2.9 times (40.0 mmol g) at 25°C. -1 ), and it is also 2.4 times higher than H-ZISv / Ag ( Figure 6b). This significant difference indicates that Au-Ag HAPs have stronger catalytic activity than the single component, due to the stronger light absorption of Au-Ag HAPs. Subsequently, the apparent quantum efficiency (AQE) of H-ZISv / Au-Ag was measured at 420 nm to be 4.4%, indicating that this material has excellent photon-to-hydrogen conversion ability and effectively utilizes photogenerated charge carriers to drive the hydrogen evolution reaction. To elucidate the photothermal effect of Au-Ag, such as... Figure 6 As shown in Figure c, when the temperature increased from 5℃ to 25℃, H-ZISv / Au-Ag achieved a concentration increase from 4.8 mmol g. -1 h -1 Up to 16 mmol g -1 h -1 The efficiency of hydrogen evolution increased by 3.3 times. Meanwhile, H-ZISv / Au and H-ZISv / Ag increased by 2.7 times and 3.0 times, respectively. Figure 6 b). Comparison Figure 5 h indicates that Au-Ag HAPs have a stronger LSPR effect, which can enhance their photocatalytic performance by generating more high-energy hot electrons and increasing the near-field temperature of hollow nanocages. Figure 6 c indicates that the catalytic hydrogen production activity of H-ZISv / Au-Ag increases with increasing temperature. This is because higher temperatures intensify the scattering of free electrons and phonons in the metal, leading to a shorter mean free path of electrons and a stronger damping effect (increased Γ), thus increasing heat production and improving the catalytic hydrogen production rate. The energy barrier at the metal-semiconductor interface facilitates the rapid transfer of electrons from H-ZISv to Au-Ag HAPs, which are then amplified by the "nanoantennae". Furthermore, H-ZISv / Au-Ag did not show a significant performance degradation during the 750-minute cycle test. Figure 6 d).

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A H-ZISv / Au-Ag HAPs composite material, characterized in that, The H-ZISv / Au-Ag HAPs composite material is formed by loading hollow Au-Ag alloy nanoparticles on hollow ZnIn2S4 nanocages containing sulfur vacancies.

2. The process for the preparation of H-ZISv / Au-Ag HAPs composite material as claimed in claim 1, wherein, The steps are as follows: (1) dissolving ZIF-8 powder in a tannic acid aqueous solution, and obtaining YS-ZIF-8 powder after etching; (2) adding ZnCl2, indium chloride tetrahydrate and thioacetamide into a mixed solvent composed of ethanol and glycerol to obtain solution A; Then, solution A is added into the YS-ZIF-8 ethanol solution, and ZnIn2S4 nanocages, i.e. H-ZISv, are obtained through hydrothermal reaction; (3) heating HAuCl4 solution to boiling, then adding trisodium citrate dihydrate solution and Ag NPs aqueous dispersion, and stirring; then immersing the reaction system in an ice water bath, and obtaining Au-Ag HAPs through cooling and centrifugal separation; (4) dispersing Au-Ag HAPs prepared in step (3) in water, adding ZnIn2S4 nanocages prepared in step (2), and mixing through stirring and ultrasonic treatment, and then drying to obtain H-ZISv / Au-Ag HAPs composite material.

3. The process for the preparation of H-ZISv / Au-Ag HAPs composite material according to claim 2, characterized by, In step (1), the preparation steps of ZIF-8 powder are as follows: dissolving 2-methylimidazole and zinc acetate in deionized water to obtain a mixed solution; then adding zinc acetate solution, and stirring at room temperature to obtain.

4. The process for the preparation of H-ZISv / Au-Ag HAPs composite material as claimed in claim 3 wherein, In step (1), the concentration of tannic acid aqueous solution is 3-6 g / L, and 0.5-2 g of ZIF-8 powder is added per L of tannic acid aqueous solution; the etching time is 20-50 min.

5. The process for the preparation of H-ZISv / Au-Ag HAPs composites according to claim 4, characterized by, In step (2), the molar ratio of ZnCl2, indium chloride tetrahydrate and thioacetamide in solution A is 0.5-1.5:1:2, and the concentration of ZnCl2 in solution A is 0.015-0.030 mol / L.

6. The process for the preparation of H-ZISv / Au-Ag HAPs composite according to claim 5, characterized by, In step (2), the concentration of YS-ZIF-8 ethanol solution is 0.68-0.80 g / mL; the volume ratio of solution A to YS-ZIF-8 ethanol solution is 1-2:1; the hydrothermal reaction temperature is 170-190℃, and the time is 1.5-2.5 h.

7. The process for the preparation of H-ZISv / Au-Ag HAPs composites according to claim 6, characterized by, In step (3), the concentration of HAuCl4 solution is 30-60 μM, the concentration of trisodium citrate dihydrate solution is 0.3-0.6 wt%, and the concentration of Ag NPs aqueous dispersion is 0.05-0.15 g / mL.

8. The process for the preparation of H-ZISv / Au-Ag HAPs composite material as claimed in claim 7, wherein, In step (3), the volume ratio of HAuCl4 solution, trisodium citrate dihydrate solution and Ag NPs aqueous dispersion is 60-70:1:1.

3.

9. The process for the preparation of H-ZISv / Au-Ag HAPs composites according to claim 8, characterized by, In step (4), the loading amount of Au-Ag HAPs is 13-14 wt%.

10. Application of the H-ZISv / Au-Ag HAPs composite material in claim 1 in photocatalytic hydrogen production.

Images