Quaternary composite photocatalyst based on three-dimensional ordered macroporous titanium dioxide as well as preparation method and application of quaternary composite photocatalyst

Abstract

The invention discloses a quaternary composite photocatalyst based on three-dimensional ordered macroporous titanium dioxide as well as a preparation method and application of the quaternary composite photocatalyst. The quaternary composite photocatalyst comprises 3DOM TiO2 and elementary substances Ag, Ag2S and ZnSe which are uniformly loaded on the surface of the 3DOM TiO2 and in pore channels. The composite material shows remarkably enhanced photocatalytic activity in the aspects of organic pollutant crystal violet degradation and water photolysis hydrogen production; the antibacterial effect on escherichia coli is excellent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photocatalysts, and particularly relates to a quaternary composite photocatalyst based on three-dimensional ordered macroporous titanium dioxide and a preparation method and application thereof. BACKGROUND

[0002] In recent years, the over-reliance on fossil fuels has led to a sharp rise in greenhouse gas emissions, which has undoubtedly brought extremely severe challenges to the global environment. In order to effectively cope with this predicament, the development and use of renewable energy has become a top priority. Among the many renewable energies, green hydrogen has outstanding advantages. It can be used directly as fuel, and can also serve as raw material or energy carrier, and almost no harmful emissions are generated when it is burned.

[0003] Among existing hydrogen production technologies, photocatalytic technology has attracted much attention and attracted the attention of the scientific research and industrial communities because it can drive reactions using solar energy under mild conditions, without the need for additional high-temperature and high-pressure equipment, reducing energy consumption and cost, and the reaction process is green and environmentally friendly, without secondary pollution. This technology not only enables the production of green hydrogen, but also has the potential to degrade pollutants, providing a viable path to resolving energy and climate crises. However, the low light absorption efficiency of photocatalysts, low separation efficiency of photo-generated carriers, and insufficient surface reaction sites limit their widespread application. Researchers have been working to develop various advanced strategies to overcome the inherent limitations of photocatalysts, such as surface modification, construction of heterojunctions, and defect engineering. These strategies have shown great potential in improving the final catalytic performance. Among them, the construction of heterostructures provides a convenient and effective strategy for preparing high-efficiency photocatalysts, which has attracted much attention.

[0004] Titanium dioxide (TiO2) is one of the most commonly used photocatalytic semiconductors, and has been widely studied due to its chemical stability, low price, and non-toxic and non-polluting characteristics. However, the wide band gap of TiO2 (3.2 eV) limits its application in the field of photocatalysis due to its low solar energy utilization rate, high recombination rate of photo-generated carriers, and insufficient active sites.

[0005] In the past decade, significant progress has been made in the synthesis of noble metal-semiconductor heterostructure nanomaterials, although such heterostructures are mainly achieved by epitaxial growth of a noble metal shell on a semiconductor component. However, for silver nanoparticles, the synthesis of heterostructures with a uniform core-shell configuration can be achieved by partially converting anisotropic silver nanostructures into corresponding semiconductors (such as Ag2S, Ag2Se, Ag2Te). Among the known silver-based hybrid nanostructures, Ag-Ag2S heterostructures are particularly attractive, mainly due to the tunable surface plasmon resonance (SPR) effect of Ag nanoparticles, which can enhance light capture and improve photocatalytic efficiency, and broaden the light response range of TiO2 through hot electrons. For example, Zuo et al. (Zuo Y, Chen J, Yang H, et al. Ag-Ag2S quantum-dots modified TiO2 nanorod arrays with enhanced photoelectrochemical and photocatalytic properties[J]. Journal of Alloys and Compounds, 2019, 780: 347-354.) synthesized Ag-Ag2S quantum dot modified nanorod (TNR) arrays by a hydrothermal method and a wet chemical method, which had a 62% degradation rate of pollutants in a 180-minute photodegradation experiment. Although this method can improve the utilization of visible light by TiO2 and improve the separation efficiency of photo-generated carriers, its degradation effect still lags behind the current cutting-edge research in the field. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application discloses a quaternary composite photocatalyst based on three-dimensional ordered macroporous titanium dioxide, which has excellent photocatalytic degradation activity, water splitting for hydrogen production performance and antibacterial performance.

[0007] The specific technical solutions are as follows:

[0008] A quaternary composite photocatalyst based on three-dimensional ordered macroporous titanium dioxide, comprising 3DOM TiO2 and elemental Ag, Ag2S and ZnSe uniformly loaded on the surface and inside the pores of the 3DOM TiO2.

[0009] The quaternary composite photocatalyst disclosed by the application can widen the light absorption range of TiO2 by compounding Ag, Ag2S, ZnSe and TiO2, so that it has a response in the visible light range; the large specific surface area of the 3DOM structure can provide more active sites for the reaction, the slow photon effect can prolong the residence time of the photo-generated carriers in the system, which is more conducive to dye sensitization, and the 3DOM structure is helpful for the transportation of small molecules; secondly, due to the combination of Ag, Ag2S, ZnSe and TiO2, the separation efficiency of the photo-generated electron-hole pairs is significantly improved, the photocatalytic activity is improved, and the existing double S-type heterostructure can provide a new way for the photocatalytic reaction, thereby significantly improving the photocatalytic activity, the water splitting hydrogen production performance and the antibacterial performance.

[0010] It is found through experiments that, compared with the combination of any three of Ag, Ag2S, ZnSe and 3DOM TiO2 or the use of ordinary TiO2 instead of 3DOM TiO2, the catalytic activity and antibacterial performance of the prepared composite photocatalyst are weaker than those of the quaternary composite photocatalyst prepared in the application.

[0011] In the application, the 3DOM TiO2 is anatase phase, the Ag2S is monoclinic α-Ag2S, and the ZnSe is sphalerite phase.

[0012] The application further discloses a preparation method of the quaternary composite photocatalyst based on the three-dimensionally ordered macroporous titanium dioxide.

[0013] S1, uniformly mixing a titanium source, a macropore template agent and a mesopore template agent, then performing a hydrolysis reaction, and then performing calcination treatment to obtain 3DOM TiO2;

[0014] S2, mixing zinc powder, selenium powder, an alkaline substance and the 3DOM TiO2 prepared in step S1 with water to obtain a mixed solution, and then performing a hydrothermal reaction to prepare ZnSe / 3DOM TiO2;

[0015] The pH value of the mixed solution is greater than 10;

[0016] S3, mixing the ZnSe / 3DOM TiO2 prepared in step S2, a soluble silver salt and water to obtain solution A, mixing a soluble sulfide and water to obtain solution B, mixing solution A and solution B to perform a reaction, and then performing a photoreduction reaction under light to obtain the quaternary composite photocatalyst.

[0017] The application synthesizes three-dimensional ordered macroporous composite material Ag-Ag2S@ZnSe / 3DOM TiO2 through three steps of double-template hydrolysis reaction, hydrothermal reaction and photoreduction reaction. The composite material realizes light response range in full spectrum. The three-dimensional ordered macroporous structure has high specific surface area, good pore connectivity and unique light scattering and light capturing effect. The structure can provide more active sites for photocatalytic reaction, increase the contact area of reactants and catalysts, and the slow photon effect further improves the light utilization efficiency and enhances the photocatalytic activity. In the photocatalytic degradation experiment for 120 minutes, the degradation rate of pollutants reaches 96%, and the stability of the material is obviously improved. The hydrogen evolution amount reaches 760.50 μmol·g −1 .

[0018] The pH value of the mixed solution in the control step S2 is particularly crucial in the preparation method. It is found through experiments that if the pH value of the mixed solution is 10 or less than 10, the three-dimensional ordered structure in the prepared ZnSe / 3DOM TiO2 will collapse a lot, resulting in the appearance of a similar sea urchin-like morphology in the finally prepared product. Further tests show that the photocatalytic activity of the four-element composite photocatalyst with the morphology will decrease significantly.

[0019] Preferably, the pH value of the mixed solution is controlled to be greater than or equal to 12.

[0020] In step S1,

[0021] The titanium source is selected from one or more of tetra-n-butyl titanate, tetra-isobutyl titanate, tetra-isopropyl titanate, tetra-ethyl titanate and tetra-methyl titanate;

[0022] The macropore template agent is selected from polystyrene microspheres and / or polymethyl methacrylate microspheres;

[0023] The macropore template agent needs to be swollen with an organic solvent before use, and the organic solvent is selected from one or more of methanol, ethanol, isopropanol and n-butanol;

[0024] The mesopore template agent is selected from one or more of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, polyethylene glycol, polyethylene oxide, alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether and fatty acid polyoxyethylene;

[0025] Preferably, the mass ratio of the macropore template agent, the titanium source and the mesopore template agent is 1:(0.2-5.0):(0.2-2.0).

[0026] Preferably, in step S1,

[0027] The calcination treatment is two-step calcination, the first step is calcination at 450-550℃ for 0.5-1.5h, and the second step is calcination at 550-620℃ for 2-8h.

[0028] In step S2:

[0029] Preferably, the zinc powder and the selenium powder are added in equimolar amounts.

[0030] Preferably, the mass ratio of 3DOM TiO2 to zinc powder is 1:(1-3); further preferably, the mass ratio of the two is 1:(1.3-2.7); more preferably, the mass ratio of the two is 1:1.3.

[0031] Preferably, the alkaline substance is selected from the common types in the art, specifically one or more of potassium hydroxide, sodium hydroxide, ethylenediamine, and hydrazine hydrate;

[0032] Preferably, the temperature of the hydrothermal reaction is 100-140℃.

[0033] In step S3:

[0034] The soluble silver salt is selected from the common types in the art, specifically one or more of silver nitrate, silver sulfate, silver chloride, and silver diamminonitrate;

[0035] Preferably, the mass ratio of ZnSe / 3DOM TiO2 to the soluble silver salt is 1:(0.01-0.1); further preferably, 1:(0.04-0.06).

[0036] The concentration of the soluble silver salt in solution A is 0.1-0.5g / L; preferably, 0.1-0.3g / L.

[0037] The soluble sulfide is selected from the common types in the art, specifically one or more of sodium sulfide, potassium sulfide, thioacetamide, and thiourea;

[0038] Preferably, the concentration of solution B is 0.05-0.5g / L; further preferably, 0.05-0.1g / L.

[0039] Preferably, the volume ratio of solution A to solution B is (0.5-2.0):1; further preferably, the two are mixed in equal volumes.

[0040] In step S3:

[0041] The photoreduction reaction uses a xenon lamp as the light source, the light irradiation power is 200-500W, and the light irradiation time is 10-60min; preferably, a 300W xenon lamp is used for irradiation for 20-40min.

[0042] The application further discloses application of the quaternary composite photocatalyst of the three-dimensional ordered macroporous titanium dioxide in photocatalytic degradation of organic matters and photolysis of water to produce hydrogen.

[0043] Preferably, the organic matter is selected from crystal violet.

[0044] Tests show that the quaternary composite photocatalyst has better photodegradation effect on crystal violet under simulated sunlight and visible light.

[0045] Tests show that the quaternary composite photocatalyst has excellent hydrogen production capacity, and the maximum hydrogen production amount can reach 760.50 μmol·g −1 after 8 h irradiation of a 300 W xenon lamp, and the quaternary composite photocatalyst still has a high retention rate after three cycles.

[0046] The application further discloses application of the quaternary composite photocatalyst of the three-dimensional ordered macroporous titanium dioxide in inhibition of growth of escherichia coli.

[0047] Tests show that the quaternary composite photocatalyst has excellent antibacterial effect.

[0048] Compared with the prior art, the application has the following beneficial effects:

[0049] The application discloses a preparation method of a three-dimensional ordered macroporous composite material Ag-Ag2S@ZnSe / 3DOM TiO2 which is synthesized through three steps of a bimodal template hydrolysis reaction, a hydrothermal reaction and a photoreduction reaction, and the quaternary composite photocatalyst realizes a light response range in a full spectrum, the three-dimensional ordered macroporous structure has a high specific surface area, good pore connectivity and unique light scattering and light capturing effects. The structure can provide more active sites for a photocatalytic reaction, increase a contact area of reactants and the catalyst, meanwhile, a slow photon effect further improves light utilization efficiency and enhances photocatalytic activity. In a 120-minute photocatalytic degradation experiment, the degradation rate of the material on pollutants reaches 96%, and stability of the material is obviously improved, and the hydrogen production amount reaches 760.50 μmol·g −1 under 8 h photolysis of water to produce hydrogen; and the material has excellent antibacterial performance. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 The SEM image of the PS microspheres used in Example 1;

[0051] Figure 2 The SEM image of the ZnSe / 3DOM TiO2 prepared in Example 1;

[0052] Figure 3SEM image of the final product Ag-Ag2S@ZnSe / 3DOM TiO2 prepared in Example 1;

[0053] Figure 4 XPS image of the final product Ag-Ag2S@ZnSe / 3DOM TiO2 prepared in Example 1;

[0054] Figure 5 UV-Vis diffuse absorption spectrum of the final product Ag-Ag2S@ZnSe / 3DOM TiO2 prepared in Example 1;

[0055] Figure 6 SEM image of the final product Ag-Ag2S@ZnSe / 3DOM TiO2 (b) prepared in Comparative Example 3;

[0056] Figure 7 The experimental results of the degradation of crystal violet by Ag-Ag2S@ZnSe / 3DOM TiO2 prepared in Example 1 under simulated sunlight irradiation, and comparative data of no catalyst, TiO2 monomer, 3DOM TiO2, ZnSe / 3DOM TiO2, and ZnSe / TiO2 as catalysts are also given in the figure;

[0057] Figure 8 The experimental results of the degradation of crystal violet by Ag-Ag2S@ZnSe / 3DOM TiO2 prepared in Example 1 under visible light, and comparative data of no catalyst, TiO2 monomer, 3DOM TiO2, ZnSe / 3DOM TiO2, and ZnSe / TiO2 as catalysts are also given in the figure;

[0058] Figure 9 The reaction rate graph of the degradation of crystal violet by Ag-Ag2S@ZnSe / 3DOM TiO2 prepared in Example 1 under simulated sunlight irradiation, and comparative data of no catalyst, TiO2 monomer, 3DOM TiO2, ZnSe / 3DOM TiO2, and ZnSe / TiO2 as catalysts are also given in the figure;

[0059] Figure 10 The experimental results of the degradation of crystal violet by catalysts prepared in Example 1 and Comparative Examples 1-3 under simulated sunlight irradiation;

[0060] Figure 11 The experimental results of the degradation of crystal violet by catalysts prepared in Example 1 and Comparative Examples 1-3 under visible light;

[0061] Figure 12 The experimental results of the degradation of crystal violet by catalysts prepared in Examples 1-3 under simulated sunlight irradiation;

[0062] Figure 13 A result graph of hydrogen production amount when the quaternary composite photocatalyst finally prepared in Example 1 is used as a photocatalyst for a water photolysis hydrogen production reaction, in which comparative data of using TiO2, 3DOM TiO2, and ZnSe / 3DOM TiO2 as photocatalysts, respectively, are also given;

[0063] Figure 14 A cycle result graph of water photolysis of the Ag-Ag2S@ZnSe / 3DOM TiO2 composite photocatalyst prepared in Example 1;

[0064] Figure 15 The antibacterial performance of 3DOM TiO2, ZnSe / 3DOM TiO2, and Ag-Ag2S@ZnSe / 3DOM TiO2 composite materials is evaluated using E. coli (a gram-negative bacterium) as a model system. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. The specific conditions not noted in the embodiments are carried out according to conventional conditions or the conditions suggested by the manufacturers. The reagents or instruments not noted by the manufacturers are all conventional products that can be purchased in the market.

[0066] The features and performances of the present application are further described in detail below in combination with the embodiments.

[0067] Example 1

[0068] S1, 1g of polystyrene microspheres (average particle size D50 of 250nm) is weighed and mixed with 1.5mL of methanol (99.5%) to swell the PS microspheres; the swollen PS microspheres, 1.5mL of tetraisobutyl titanate, and 0.5mL of P123 are mixed uniformly, and a hydrolysis reaction is carried out at room temperature, and the hydrolysis product is calcined at 500℃ for 1h and at 600℃ for 7h to prepare highly ordered 3DOM TiO2;

[0069] S2, 0.25g of 3DOM TiO2 prepared in step S1, 1.7590g of potassium hydroxide, 0.3250g of zinc powder, 0.1950g of selenium powder, and 30mL of deionized water are mixed uniformly, and the pH value of the obtained mixture is 12; the mixture is hydrothermally reacted at 120℃ for 2h to prepare ZnSe / 3DOM TiO2;

[0070] S3, 0.2 g of ZnSe / 3DOM TiO2 prepared in step S2, 0.0093 g of silver nitrate and 40 mL of deionized water were mixed to obtain solution A; 0.0028 g of sodium sulfide and 40 mL of deionized water were mixed to obtain solution B; the two were mixed and reacted thoroughly, and then were placed in a photoreactor and irradiated by a 300 W xenon lamp for 30 min. The obtained precipitate was washed with ethanol and deionized water for 3 times respectively, and then was placed in a drying oven at 60°C for drying treatment for 12 h to obtain the final product, which was recorded as Ag-Ag2S@ZnSe / 3DOM TiO2.

[0071] Figure 1 The SEM image of the PS microspheres used in this embodiment was observed, and it was found that the particle size was uniform, the PS microspheres were assembled into opal structure with an average diameter of about 250 nm, and were densely packed into face-centered cubic.

[0072] Figure 2 The SEM image of ZnSe / 3DOM TiO2 prepared in step S2 of this embodiment was observed, and it was found that the microstructure of the composite material was a three-dimensional ordered macroporous structure, each pore bottom of the material had three symmetrically distributed small holes, and each macropore channel had a highly ordered hexagonal structure, which was connected to the surrounding six macropores to form a three-dimensional ordered array structure.

[0073] Figure 3 The SEM image of the final product Ag-Ag2S@ZnSe / 3DOM TiO2 prepared in this embodiment was observed, and it was found that the final product still presented a three-dimensional ordered macroporous structure, the macroporous structures were interconnected, the overall arrangement was regular and ordered, and a unique morphology similar to a honeycomb was formed on a macroscopic scale. This highly ordered three-dimensional porous framework greatly increased the specific surface area of the material, not only constructed efficient channels for the transmission and diffusion of substances, but also provided abundant active sites for the photocatalytic reaction, thereby improving the photocatalytic reaction efficiency. Further microscopic observation of the macropore wall surface found that Ag-Ag2S and ZnSe nanoparticles were uniformly distributed on the surface of the TiO2 pore wall. These nanoparticles were uniform in size and closely embedded in the TiO2 pore wall, forming a stable and efficient bonding interface with the substrate. This interface structure not only ensures the close contact between different components, creates favorable conditions for the rapid migration and separation of photo-generated carriers, but also strengthens the synergistic effect of the composite material, which is of great significance to improve its photocatalytic performance.

[0074] Figure 4XPS spectra of the final product Ag-Ag2S@ZnSe / 3DOM TiO2 prepared for this example. As shown in the figure, the analysis shows that there are Ag, Ti, Zn, Se, S and O elements on the surface of the Ag-Ag2S@ZnSe / 3DOM TiO2 sample. The analysis of the Ag 3d XPS spectrum in the figure shows that the double peaks at 367.18 eV and 373.18 eV correspond to the Ag 3d 5 / 2 and Ag 3d 3 / 2 orbital characteristics, and the peak intensity ratio (3:2) is consistent with the chemical state characteristics of Ag + in the sample. Another set of split peaks observed at 368.18 eV and 374.18 eV, and the binding energy interval is 6.0 eV, and this set of signals is attributed to the characteristic peaks of metallic silver Ag 0 . The coexistence of the two pairs of characteristic peaks indicates that Ag + and Ag 0 exist in the material in two valence states, in which Ag 0 may be related to the occurrence of the reduction reaction in the preparation process, and Ag + exists due to surface oxidation, which confirms that silver elements exist in the composite system in mixed valence states. The Ti 2p XPS spectrum is shown in the figure, and there are double peaks at 458.48 eV and 463.88 eV, which correspond to Ti 2p 3 / 2 and Ti 2p 1 / 2 orbital characteristics, and the binding energy interval of 5.4 eV is consistent with the standard value of tetravalent titanium (Ti 4+ ), which confirms that the titanium element in the material exists in the +4 valence state. The XPS spectrum of Zn 2p is shown in the figure, and two obvious sharp peaks can be seen at 1021.28 and 1044.28 eV, which correspond to Zn 2p 3 / 2 orbital and Zn 2p 1 / 2 orbital, respectively, proving that the valence state of Zn ions in the composite material is +2. The XPS spectrum of S 2p is shown in the figure, and there are two peak values at binding energies of 161.58 eV and 162.98 eV, indicating that the two states of S are related to S 2p 3 / 2 and S 2p 1 / 2 transitions, proving that the valence state of S ions in the composite material is -2. The XPS spectrum of Se 3d is shown in the figure, and there are two peak values at binding energies of 52.68 eV and 53.68 eV, indicating that the two states of Se are related to Se 3d 5 / 2 and Se 3d 3 / 2 transitions, proving that the valence state of Se in the composite material is -2. The O 1s XPS spectrum is shown in the figure, and the peak at 529.38 eV indicates that O 2-The appearance of the peak at 531.08 eV is characteristic of TiO2 lattice oxygen, which is present in the Ti-O-Ti mode, while the peak at 532.58 eV is consistent with -OH groups.

[0075] Figure 5 The UV-Vis diffuse absorption spectrum of the final product Ag-Ag2S@ZnSe / 3DOM TiO2 prepared in this example is shown, and the UV-Vis diffuse absorption spectra of TiO2, ZnSe, Ag2S, 3DOM TiO2 prepared in step S1, ZnSe / 3DOM TiO2 prepared in step S2 are also shown as a comparison. It can be found from the figure that compared with pure TiO2, 3DOM TiO2 has a slight red shift, because the periodic structure of three-dimensional ordered macropores and the slow photon effect generated can improve the excitation of photo-generated electrons, form more carriers, thereby improving the photocatalytic activity, and make TiO2 move to the long wave direction. When 3DOM TiO2 is compounded with ZnSe, its light absorption range is significantly extended to the visible light region. This phenomenon shows that the effective combination between ZnSe and TiO2 can break the limitation of light absorption of single material. In order to further optimize the light absorption performance of the composite material, Ag2S is introduced to modify ZnSe / 3DOM TiO2. The modified Ag-Ag2S / ZnSe / 3DOM TiO2 composite material presents full spectrum absorption. This significant red shift can be attributed to the synergistic effect between Ag2S, ZnSe and TiO2. The energy level matching and charge transfer process between different semiconductor materials promote the generation and separation of photo-generated carriers, enhance the absorption and utilization of light. In addition, the SPR effect and photosensitive effect of Ag promote the absorption and utilization of photons. Therefore, Ag-Ag2S@ZnSe / 3DOM TiO2 composite material has obvious advantages in light absorption performance.

[0076] Comparative Example 1

[0077] S1, 10 mL of titanium isobutylate was slowly stirred, and deionized water was gradually added dropwise during the stirring process. When the solution formed a sol-gel, it was dried under vacuum at 60 ℃ for 12 h; TiO2 was synthesized by calcining at 500 ℃ for 1 h and at 600 ℃ for 7 h in a muffle furnace;

[0078] Step S2 is basically the same as in Example 1, except that 3DOM TiO2 is replaced by ordinary titanium dioxide prepared in step S1 with the same mass, and the product obtained in step S2 is denoted as ZnSe / TiO2;

[0079] Step S3 is basically the same as in Example 1, with the difference that ZnSe / 3DOM TiO2 is replaced by equal mass of ZnSe / TiO2 prepared in Step S2, and the product is recorded as Ag-Ag2S@ZnSe / TiO2.

[0080] Comparative Example 2

[0081] The preparation process is basically the same as in Example 1, with the difference that:

[0082] In Step S2, the mass of deionized water is replaced by 60 mL, and the pH value of the mixed solution is 10 at this time. The product obtained is recorded as Ag-Ag2S@ZnSe / 3DOM TiO2(b).

[0083] According to SEM characterization, in the ZnSe / 3DOM TiO2 prepared in Step S2 of the present comparative example, a large number of three-dimensional ordered structures collapsed.

[0084] Figure 6 The SEM image of the product Ag-Ag2S@ZnSe / 3DOM TiO2(b) prepared for the present comparative example is shown in the figure, and the appearance similar to sea urchin can be observed, which is speculated to be caused by the change of pH value.

[0085] Comparative Example 3

[0086] The preparation process is basically the same as in Example 1, with the difference that:

[0087] In Step S3, no photoreduction reaction is carried out, and the product obtained by directly reacting solution A and solution B is washed and dried, and the product obtained is recorded as Ag2S@ZnSe / 3DOM TiO2.

[0088] Example 2

[0089] The preparation process is basically the same as in Example 1, with the difference that:

[0090] In Step S2, the mass of zinc powder is replaced by 0.678 g, and the mass of selenium powder is replaced by 0.407 g.

[0091] Example 3

[0092] The preparation process is basically the same as in Example 1, with the difference that:

[0093] In Step S2, the mass of zinc powder is replaced by 0.290 g, and the mass of selenium powder is replaced by 0.174 g.

[0094] Performance test:

[0095] I. Photocatalytic degradation of organic matter

[0096] The composite photocatalyst, TiO2, and 3DOM TiO2 prepared in step S1 of Example 1 were used as photocatalysts to photocatalytically degrade organic matter crystal violet, and the specific process was as follows:

[0097] First, 0.1250 g of organic pollutants was accurately weighed, and then an appropriate amount of deionized water was added to promote dissolution by ultrasonic treatment. After complete dissolution, the solution was transferred to a volumetric flask, and then the volume was adjusted and the solution was shaken to obtain a 500 ppm concentration of the original mother liquor of the pollutants. On this basis, 5.0 mL of the 500 ppm solution was accurately measured from the original solution, and then the volume was adjusted again to meet the concentration and volume requirements of the subsequent photocatalytic degradation experiment.

[0098] A 300 W xenon lamp was used as a simulated sunlight source, and 0.15 g of catalyst was used to react with crystal violet. First, 100 mL of a 500 ppm concentration of crystal violet solution was prepared, and 5.0 mL was taken as the original solution for standby, and the remaining solution was transferred to a beaker, different catalyst materials were added, and then the solution was ultrasonically treated for 10 min, and then stirred in the dark for 30 min. After that, it was transferred to the reactor. Turn on the 300 W xenon lamp and pass the condensate water, while stirring. After centrifugation, dilute it in proportion. Use deionized water as a reference to measure the absorbance, and calculate and draw the crystal violet degradation curve of different catalysts.

[0099] First, the photocatalytic degradation was carried out on a 300 W xenon lamp with a visible light glass installed. Then, 100 mL of a 500 ppm concentration of crystal violet solution was prepared, and 5.0 mL was taken as the original solution for standby, and the remaining solution was transferred to a beaker and stirred in the dark for 30 min. Then, 5 mL of the original solution was taken, the xenon lamp was turned on for 2 h, and the condensate water was passed while stirring. During the experiment, 0.15 g of catalyst was used in turn. After turning on the xenon lamp, the solution was taken every 5 min, and after 20 min, the solution was taken every 10 min, and after 30 min, the solution was taken every 15 min, and after 90 min, 5 mL of the solution was taken every half hour. After centrifugation, dilute it in proportion, use deionized water as a reference solution, and measure the absorbance of each sample. Finally, according to the absorbance data, the visible light photocatalytic degradation experiment results are plotted.

[0100] Figure 7 、 Figure 8 The experimental results of Ag-Ag2S@ZnSe / 3DOM TiO2 prepared in Example 1 under simulated sunlight and visible light for degrading crystal violet are shown in the figures, which also show the comparison data of not adding catalyst (control group), using TiO2 monomer, 3DOM TiO2 (prepared in step (S1) of Example 1), ZnSe / 3DOM TiO2 (prepared in step (S2) of Example 1), and ZnSe / TiO2 (prepared in step (S2) of Comparative Example 1) as catalysts.

[0101] Comparison Figure 7 It is found that the degradation rate of the solution containing only crystal violet is about 12.70% after irradiation by simulated sunlight for 120 min, while the degradation efficiency is significantly improved after adding the catalysts TiO2 monomer, 3DOM TiO2, ZnSe / TiO2, ZnSe / 3DOM TiO2, Ag-Ag2S@ZnSe / TiO2, Ag-Ag2S@ZnSe / 3DOM TiO2, and the degradation rates are about 23.20%, 33.20%, 40.80%, 79.00%, 89.00%, and 96.80%, respectively. Apparently, the quaternary composite photocatalyst Ag-Ag2S@ZnSe / 3DOM TiO2 prepared in this embodiment exhibits the highest photocatalytic performance. On the one hand, the three-dimensional ordered macroporous morphology provides a large specific surface area for the reaction to provide more active sites, and also promotes the diffusion of the reactants, which is more conducive to the reaction of the composite material with the dye molecules to degrade the pollutants. On the other hand, the heterostructure formed by Ag, Ag2S, ZnSe, and TiO2 is more conducive to the adsorption of substances, and can further improve the separation efficiency of photo-generated carriers to promote the catalytic reaction process.

[0102] Comparison Figure 8 In the visible light photocatalytic degradation experiment, the Ag-Ag2S@ZnSe / 3DOM TiO2 composite material is compared with other materials TiO2, 3DOM TiO2, ZnSe / TiO2, ZnSe / 3DOM TiO2, and Ag-Ag2S@ZnSe / TiO2. The degradation rate of the crystal violet solution is about 8.80% under the irradiation of visible light, while the catalytic activity is significantly enhanced after adding the catalysts. Under visible light irradiation, Ag-Ag2S@ZnSe / 3DOM TiO2 still has good degradation effect on crystal violet. This is due to the fact that elemental silver exhibits strong surface plasmon resonance effect in the visible light region. This effect broadens the light response interval of the composite material, and thus improves its utilization degree of visible light. At the same time, the pore size of the three-dimensional ordered macroporous structure can be adjusted, so that the light capture efficiency in the visible light is greatly improved. In addition, 3DOM TiO2 presents a regularly arranged honeycomb interface, which provides more active sites for the photocatalytic reaction, and is conducive to the loading of silver sulfide and zinc selenide, thereby enhancing the photocatalytic performance of the Ag-Ag2S@ZnSe / 3DOM TiO2 composite material.

[0103] Figure 9 The reaction rate diagram of the above-mentioned various catalysts in the degradation of crystal violet under simulated sunlight irradiation, the experimental data of different catalysts on the degradation of crystal violet under simulated sunlight irradiation, and the kinetic curve analysis reflect the effect of each condition on the degradation effect. The-ln(C tC0 represents the initial concentration of crystal violet, C represents the concentration of crystal violet at time t, and k represents the reaction rate constant. t C represents the concentration of crystal violet at time t, and k represents the reaction rate constant. t C0=kt, which is approximately linear, indicating that the process conforms to first-order reaction kinetics and that the degradation rate of Ag-Ag2S@ZnSe / 3DOM TiO2 is the fastest.

[0104] Figure 10 The experimental results of the catalysts prepared in Example 1, Comparative Examples 1, 2, and 3 in degrading crystal violet under simulated sunlight irradiation are as follows: under 300W xenon lamp irradiation for 120 minutes, the removal rates of crystal violet by the catalysts are Ag2S@ZnSe / 3DOM TiO2<Ag-Ag2S@ZnSe / 3DOM TiO2(b)<Ag-Ag2S@ZnSe / TiO2<<Ag-Ag2S@ZnSe / 3DOM TiO2, wherein the removal rate of crystal violet by Ag2S@ZnSe / 3DOM TiO2 is 63.27% in 120 minutes, which is the worst, and the removal rate of crystal violet by Ag-Ag2S@ZnSe / 3DOM TiO2 is the best.

[0105] Figure 11 The experimental results of the catalysts prepared in Example 1, Comparative Examples 1, 2, and 3 in degrading crystal violet under visible light irradiation are as follows: under visible light irradiation for 120 minutes, the removal rates of crystal violet by the catalysts are Ag2S@ZnSe / 3DOM TiO2<Ag-Ag2S@ZnSe / 3DOM TiO2(b)<Ag-Ag2S@ZnSe / TiO2<<Ag-Ag2S@ZnSe / 3DOM TiO2. Ag2S@ZnSe / 3DOM TiO2 has the worst removal effect on crystal violet in 120 minutes, and Ag-Ag2S@ZnSe / 3DOM TiO2 has the best removal effect, which may be because the Ag-Ag2S@ZnSe / 3DOM TiO2 composite material can efficiently capture a wide range of visible light by using the plasmonic resonance effect of metal particles, thereby greatly improving the utilization rate of sunlight.

[0106] Figure 12 The experimental results of the catalysts prepared in Example 1~3 in degrading crystal violet under simulated sunlight irradiation are as follows: the Ag-Ag2S@ZnSe / 3DOM TiO2 in Example 1 has the best degradation effect.

[0107] II. Hydrogen production by photolysis of water

[0108] The quaternary composite photocatalyst prepared in Example 1, TiO2, 3DOM TiO2 prepared in step S1 of Example 1, and ZnSe / 3DOM TiO2 prepared in step S2 were used as photocatalysts for the water splitting reaction to produce hydrogen, and the specific process was as follows:

[0109] The photocatalytic water splitting reaction to produce hydrogen was carried out using a Pefailab LabSolar-IIIAG photocatalytic online analysis system. 0.15 g of the catalyst was placed in the reactor. The magnetic stirrer was turned on, the 300 W xenon lamp was used for irradiation, and the DC-0506 low-temperature condensation tank was used for cooling the photocatalytic reaction system. The protective cover was covered and argon was continuously introduced as protection, and the light was irradiated for 8 h. The hydrogen production amount was calculated by the Tianmei GC-7900, the peak area was calculated by the gas phase software, and the hydrogen production amount was calculated by substituting the formula.

[0110] Figure 13 The results of the hydrogen production amount of the above-mentioned various catalysts in the water splitting reaction to produce hydrogen were compared, and it was found that the water splitting reaction to produce hydrogen of the composite material Ag-Ag2S@ZnSe / 3DOM TiO2 was significantly enhanced, and the hydrogen production amount (760.50 μmol·g −1 , 8 h) reached 7.91 times that of TiO2. This is because the catalyst has a three-dimensional highly interconnected network of nanometer space, which can effectively increase the active sites of the reaction and is more conducive to the enhancement of the water splitting reaction to produce hydrogen.

[0111] Figure 14 The results of the water splitting reaction to produce hydrogen of the Ag-Ag2S@ZnSe / 3DOM TiO2 composite photocatalyst prepared in Example 1 were shown in the figure, and it could be seen from the figure that after 3 cycles, the Ag-Ag2S@ZnSe / 3DOM TiO2 still had a certain water splitting reaction to produce hydrogen ability, and it was considered that the material had good stability.

[0112] Three, antibacterial experiment

[0113] Using E. coli as a model gram-negative bacteria, the antibacterial activity of the composite material was evaluated. The E. coli was cultured in the medium at 37℃ for 30 min, the bacterial suspension was centrifuged at 500 rpm·min -1 , the supernatant was discarded, physiological saline was introduced, and the optical density was 0.5 measured by the ultraviolet-visible spectrometer. 0.5 mL of Ag-Ag2S@ZnSe / 3DOM TiO2 (200 μg·mL -1), ZnSe / 3DOM TiO2, 3DOM TiO2, respectively, were mixed with 1 mL of cultured bacteria, and irradiated for 30 min under the condition of 300 W xenon lamp simulated sunlight irradiation. The control group was changed to non-irradiated bacterial suspension and non-irradiated salt bacterial suspension under the same conditions. The suspension was diluted 103 times, and 40 μL was taken and plated on LB-agar plates, and incubated at 37°C for 20 h. Finally, the antibacterial rate was calculated by viable bacterial colony counting method, and the blank sample was used as the reference sample.

[0114] Figure 15 The antibacterial results of the Ag-Ag2S@ZnSe / 3DOM TiO2 composite photocatalyst prepared in Example 1 are shown in the graph. First, the catalyst was added, and the sample was allowed to stand in the dark for 30 minutes, and then treated under light for 30 minutes to form the experimental control group. Then the sample was incubated at 37°C for 20 hours for observation of the antibacterial performance of the material. As can be seen from the graph, after only dark and incubation, the antibacterial effect of the composite material Ag-Ag2S@ZnSe / 3DOM TiO2 has a significant increase. After 30 min of light, the antibacterial effect of each composite material is enhanced, among which the composite material Ag-Ag2S@ZnSe / 3DOM TiO2 shows a significant inactivation effect on E. coli, with 89.85% cell death, which is due to the three-dimensional ordered macroporous network structure that can effectively capture a large number of bacteria and promote the antibacterial process. In the control group experiment without adding antibacterial agent, the survival rate of bacteria is higher, indicating that the material can effectively inhibit the growth of E. coli.

[0115] The above discloses the preferred embodiments, but the protection scope of the present application is not limited thereto, and those skilled in the art can easily understand the spirit of the present application according to the above embodiments, and make different inferences and changes, as long as they do not deviate from the spirit of the present application, they are within the protection scope of the present application.

Claims

1. A quaternary composite photocatalyst based on three-dimensional ordered macroporous titanium dioxide, characterized in that: The invention comprises 3DOM TiO2 and single substance Ag, Ag2S and ZnSe uniformly loaded on the surface and inside the pores of the 3DOM TiO2.

2. The quaternary composite photocatalyst based on three-dimensional ordered macroporous titanium dioxide according to claim 1, characterized in that: The 3DOM TiO2 is in anatase phase, the Ag2S is monoclinic α-Ag2S, and the ZnSe is in sphalerite phase.

3. A method for preparing a quaternary composite photocatalyst based on three-dimensional ordered macroporous titanium dioxide according to claim 1 or 2, characterized in that: include: S1, mixing the titanium source, macroporous template agent and mesoporous template agent uniformly, performing hydrolysis reaction, and then calcining to obtain 3DOM TiO2; S2, mixing zinc powder, selenium powder, alkaline substance and 3DOM TiO2 prepared in step S1 with water to obtain a mixed solution, and preparing ZnSe / 3DOM TiO2 after hydrothermal reaction; The pH value of the mixed solution is >10; S3. The ZnSe / 3DOM TiO2 prepared in step S2 and a soluble silver salt are mixed with water to obtain a solution A, the soluble sulfide is mixed with water to obtain a solution B, and then the solution A and the solution B are mixed to react, and then a photoreduction reaction is carried out under light conditions to obtain the quaternary composite photocatalyst.

4. The method for preparing a quaternary composite photocatalyst based on three-dimensional ordered macroporous titanium dioxide according to claim 3, characterized in that: In step S1: The titanium source is selected from one or more of tetra-n-butyl titanate, tetra-isobutyl titanate, tetra-isopropyl titanate, tetra-ethyl titanate, and tetra-methyl titanate; The macroporous template agent is selected from polystyrene microspheres and / or polymethyl methacrylate microspheres; The macroporous template agent needs to be swollen with an organic solvent before use, and the organic solvent is selected from one or more of methanol, ethanol, isopropanol, and n-butanol; The mesoporous template is selected from one or more of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, polyethylene glycol, polyethylene oxide, alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, and fatty acid polyoxyethylene; The mass ratio of the macroporous template, the titanium source and the mesoporous template is 1: (0.2~5.0): (0.2~2.0).

5. The method for preparing a quaternary composite photocatalyst based on three-dimensional ordered macroporous titanium dioxide according to claim 3, characterized in that: In step S1: The calcination process is a two-step calcination process, wherein the first step is calcination at 450-550° C. for 0.5-1.5 hours, and the second step is calcination at 550-620° C. for 2-8 hours.

6. The method for preparing a quaternary composite photocatalyst based on three-dimensional ordered macroporous titanium dioxide according to claim 3, characterized in that: In step S2: The zinc powder and the selenium powder are added in equal moles; The mass ratio of 3DOM TiO2 to zinc powder is 1:(1~3); The alkaline substance is selected from one or more of potassium hydroxide, sodium hydroxide, ethylenediamine, and hydrazine hydrate; The pH value of the mixed solution is ≥12; The temperature of the hydrothermal reaction is 100-140°C.

7. The method for preparing a quaternary composite photocatalyst based on three-dimensional ordered macroporous titanium dioxide according to claim 3, characterized in that: In step S3: The soluble silver salt is selected from one or more of silver nitrate, silver sulfate, silver chloride, and diammine silver nitrate; The mass ratio of ZnSe / 3DOM TiO2 to soluble silver salt is 1:(0.01~0.1); The concentration of soluble silver salt in solution A is 0.1~0.5g / L; The soluble sulfide is selected from one or more of sodium sulfide, potassium sulfide, thioacetamide, and thiourea; The concentration of solution B is 0.05~0.5g / L; The volume ratio of solution A to solution B is (0.5~2.0):

1.

8. The method for preparing a quaternary composite photocatalyst based on three-dimensional ordered macroporous titanium dioxide according to claim 3, characterized in that: In step S3: The photoreduction reaction uses a xenon lamp as a light source, the illumination power is 200-500W, and the illumination time is 10-60 minutes.

9. Use of the four-component composite photocatalyst of three-dimensional ordered macroporous titanium dioxide according to claim 1 or 2 in photocatalytic degradation of organic matter and photocatalytic water splitting to produce hydrogen.

10. Use of the four-component composite photocatalyst of three-dimensional ordered macroporous titanium dioxide according to claim 1 or 2 in inhibiting the growth of Escherichia coli.

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