Composite photo-thermal catalytic material of TiO2 / Ag / TiO2 loaded Au nanoparticles and preparation method of composite photo-thermal catalytic material

Abstract

The invention discloses a TiO2 / Ag / TiO2 loaded Au nanoparticle composite photo-thermal catalytic material which is characterized by comprising a substrate, and a TiO2 layer, an Ag layer, a TiO2 film layer and an Au nanoparticle layer are sequentially arranged on the upper surface of the substrate from bottom to top. The photocatalytic material taking TiO2 as the substrate is constructed by adopting methods such as precious metal modification and nano-particle deposition, the material can form an Au-Ag plasmon resonance effect, and meanwhile, the yield of H2O2 is improved by utilizing a precious metal deposition effect. The catalyst prepared by the invention has the advantages of less usage amount of noble metal, lower cost, no secondary pollution in the catalysis process, convenience in recovery of the film deposited on the glass slide, and facilitation of realization of industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of photothermal catalytic materials, and particularly relates to a composite photothermal catalytic material of TiO2 / Ag / TiO2 loaded with Au nanoparticles and a preparation method thereof. Background Art

[0002] Since hydrogen peroxide (H2O2) was first synthesized by Thenard in 1818 through the reaction of barium peroxide and nitric acid, H2O2 has attracted increasing attention and is listed as one of the 100 most important chemicals in the world. H2O2 is an efficient and environmentally friendly oxidant that does not produce toxic by-products during the reaction, only producing H2O and oxygen (O2). According to the reaction characteristics, H2O2 has been widely used in fields such as organic synthesis, wastewater treatment and disinfection, and the pulp and paper industry.

[0003] Currently, the anthraquinone (AQ) method dominates the production of H2O2, accounting for approximately 95% of the global H2O2 production. Although the AQ oxidation technology is mature, it has disadvantages such as high energy consumption, dangerous operation, and environmental pollution. In addition, the direct synthesis of H2O2 from H2 and O2 is more environmentally friendly, but it has a high cost, lacks selectivity for H2O2, and the mixture of H2 and O2 is prone to explosion.

[0004] Therefore, people have been committed to developing new methods for producing H2O2. Solar energy is a clean and sustainable energy source. Since Fujishima and Honda discovered the photo-assisted oxidation of water on a TiO2 electrode in 1972, the catalytic effect of semiconductor photocatalytic materials has been studied in multiple research fields. The photocatalytic production of H2O2 is a safe and green process using renewable solar energy as the energy source and H2O and O2 as raw materials. In the long run, the photocatalytic production of H2O2 has great potential in environmental pollution control.

[0005] In recent years, a large number of related studies have emerged in the field of semiconductor photocatalytic production of H2O2. However, the low visible light utilization rate and low solar energy conversion efficiency of the semiconductor TiO2 material have seriously hindered its commercial feasibility. Currently, in order to improve the efficiency of TiO2 photocatalytic production of H2O2, researchers have adopted various modification methods, such as doping, vacancy engineering, surface engineering, nanoparticle deposition, heterostructure construction, noble metal modification, etc., and combinations of two or more of these methods to modify it.

[0006] Regarding the modification of noble metals and the deposition of noble metal nanoparticles, it is worth studying that the plasmon coupling between adjacent noble metal nanoparticles can form a plasmon coupling band with a longer wavelength than the LSPR band of a single noble metal nanoparticle, and the spacer band between noble metals can act as a hot spot to highly concentrate and amplify the energy of plasmon resonance. However, the poor controllability of the number of nanoparticles and the interparticle distance hinders the exploration of the plasmon-coupled photocatalytic effect. Since plasmon resonance is very sensitive to the coupling distance between particles and the number of particles present, studying different particle contents is crucial for regulating the plasmonic properties of the hybrid structure and the corresponding photocatalytic activity. This patent studies the number of particles with different contents. Summary of the Invention

[0007] The purpose of the present invention is to provide a composite photothermal catalytic material of TiO2 / Ag / TiO2 loaded with Au nanoparticles, and at the same time provide a preparation method for the catalytic material.

[0008] To achieve the above purpose, the present invention adopts the following technical solutions:

[0009] A composite photothermal catalytic material of TiO2 / Ag / TiO2 loaded with Au nanoparticles, including a substrate, on the upper surface of which there are successively provided a TiO2 layer, an Ag layer, a TiO2 thin film layer, and an Au nanoparticle layer from bottom to top.

[0010] For better results, preferably, the thickness of the TiO2 layer is 100 - 120 nm, the thickness of the Ag layer is 20 - 25 nm, the thickness of the TiO2 thin film layer is 15 - 25 nm, and the thickness of the Au nanoparticle layer is 1.5 - 10 nm.

[0011] Preferably, the thickness of the TiO2 layer is 100 nm, the thickness of the Ag layer is 20 nm, the thickness of the TiO2 thin film layer is 20 nm, and the thickness of the Au nanoparticle layer is 2.5 nm.

[0012] Preferably, the substrate is a glass slide, a PVA water-soluble film, or K9 glass. The selection of the substrate material requires that it does not react with the solution to be degraded or reacted in subsequent use, and it is a plane with a uniform thickness distribution. The preparation method of the above composite photothermal catalytic material of TiO2 / Ag / TiO2 loaded with Au nanoparticles includes the following steps:

[0013] S1. Place the cleaned substrate on the substrate of electron beam evaporation, place it in the electron beam cavity, put the TiO2 and Ag target crucibles, close the cavity door, and pump the vacuum degree in the equipment chamber to 10e -4After the following steps, turn on the electron gun device, slowly adjust the gun filament beam current to 1 - 1.2 A, adjust the electron beam spot position to the center of the crucible, adjust the electron gun beam current to 50 - 70 A, and perform melting evaporation coating on the TiO2 target. The coating rate is stable at After that, open the substrate baffle and evaporate the TiO2 layer on the substrate surface; then adjust the gun filament beam current to 0 A, replace the crucible target with an Ag target, adjust the gun filament beam current to about 1 - 1.2 A again, adjust the electron beam spot position to the center of the crucible, adjust the electron gun beam current to 35 - 50 A, and the coating rate is stable at After that, evaporate the Ag layer on the TiO2 layer; adjust the size of the gun filament beam current to 0 A again, after replacing the crucible target with a TiO2 target, adjust the gun filament beam current to 1 - 1.2 A, adjust the electron gun beam current to 50 - 70 A, and the coating rate is stable at Evaporate the TiO2 thin film layer on the Ag layer, and the electron beam evaporation of the thin film is completed.

[0014] S2. Sputter Au nanoparticles on the evaporated TiO2 thin film layer by magnetron sputtering. When magnetron sputtering the Au target, the excitation current is 20 - 30 mA, and the sputtering time is 3 - 20 s.

[0015] Preferably, when evaporating the TiO2 layer in S1, the gun filament beam current is 1.2 A; the electron gun beam current is 70 A, and the coating rate is

[0016] When evaporating the Ag layer, the gun filament beam current is 1.2 A, the electron gun beam current is 50 A, and the coating rate is

[0017] When evaporating the TiO2 thin film layer, the gun filament beam current is 1.2 A, the electron gun beam current is 70 A, and the coating rate is

[0018] Preferably, in S2, when magnetron sputtering the Au target, the excitation current is 25 mA, and the sputtering time is 5 s.

[0019] Preferably, the substrate is a glass slide, the glass slide is 20×25 mm. The glass slide is ultrasonically cleaned in soapy water and deionized water for 10 minutes in sequence, rinsed with deionized water 3 times, ultrasonically cleaned in acetone and absolute ethanol for 15 minutes in sequence, and the cleaned glass slide is stored in an absolute ethanol solution for standby. When used, take out the glass slide and dry it under argon for use.

[0020] The present invention has the following beneficial effects compared with the prior art:

[0021] The present invention constructs a photocatalytic material based on TiO2 by means of noble metal modification and nanoparticle deposition. This material can form plasmon resonance effects such as Au-Ag, and at the same time, the yield of H2O2 is increased by using the effect of noble metal deposition.

[0022] In the catalyst prepared by the present invention, the amount of noble metal used is small, the cost is low, and no secondary pollution is generated during the catalytic process. The thin film deposited on the glass slide is convenient for recycling, which helps to realize industrial production.

[0023] The thin film material grown on the surface of the glass slide by physical vapor deposition in the present invention is convenient for controlling the thickness of the thin film deposition. With less target materials used, a dense thin film is deposited, providing a large number of adsorption sites and active sites for the photocatalytic reaction process. The preparation method by electron beam evaporation is convenient for adjusting the thickness of the TiO2 spacer layer between Au and Ag, controlling the spacing between Au and Ag metal nanoparticles, adjusting the plasma characteristics of the hybrid structure and enhancing the photocatalytic activity of the material, and controlling the influence of the Au-Ag spacing on the photocatalytic effect. The Au nanoparticles deposited by magnetron sputtering can form a plasmon resonance effect with the Ag thin film, enhancing the catalytic reaction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the composite photothermal catalytic material of the present invention.

[0025] Figure 2 It is the SEM image of the composite photocatalyst TiO2 / Ag / TiO2 in the present invention and the SEM image of the composite photothermal catalytic material loaded with Au nanoparticles of TiO2 / Ag / TiO2. Among them, (a), (b), and (c) are the SEM images of TiO2 / Ag / TiO2; (d) and (e) are the SEM images of the composite photothermal catalytic material loaded with Au nanoparticles of TiO2 / Ag / TiO2; (f), (g), (h), and (i) are the energy spectrum analysis diagrams of the composite photothermal catalytic material loaded with Au nanoparticles of TiO2 / Ag / TiO2.

[0026] Figure 3 It is the photocatalytic hydrogen peroxide production performance diagram of the composite photocatalyst TiO2 / Ag / TiO2 and the composite photothermal catalytic material loaded with Au nanoparticles of TiO2 / Ag / TiO2 in the present invention.

[0027] Figure 4 It is the degradation rhodamine performance diagram of the composite photothermal catalytic material of the present invention.

[0028] In the figure: 1. Substrate; 2. TiO2 layer; 3. Ag layer; 4. TiO2 thin film layer; 5. Au nanoparticle layer. DETAILED DESCRIPTION OF THE INVENTION

[0029] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present application. It should be noted that all directional indications in the embodiments of the present application are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0030] In the present application, unless otherwise clearly defined and limited, the terms "connection", "fixation", etc. shall be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the connection inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0031] In addition, in the present application, descriptions such as "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0032] As Figure 1 shown, a composite photothermal catalytic material of TiO2 / Ag / TiO2 loaded with Au nanoparticles includes a substrate 1. On the upper surface of the substrate 1, a TiO2 layer 2, an Ag layer 3, a TiO2 thin film layer 4, and an Au nanoparticle layer 5 are sequentially provided from bottom to top. The substrate 1 is a glass slide. The thickness of the TiO2 layer 2 is 100 - 120 nm; the thickness of the Ag layer 3 is 20 - 25 nm; the thickness of the TiO2 thin film layer 4 is 15 - 20 nm, and the thickness of the Au nanoparticle layer is 1.5 - 10 nm.

[0033] Example 1

[0034] A preparation method of a composite photothermal catalytic material of TiO2 / Ag / TiO2 loaded with Au nanoparticles includes the following steps:

[0035] S1. First, cut the glass slide into a 20×25 mm glass slide, clean the glass slide, ultrasonically clean the glass slide in soapy water and deionized water for 10 minutes in sequence, then rinse it 3 times with deionized water, and then ultrasonically clean it in acetone and absolute ethanol for 15 minutes. Store the cleaned glass slide in an absolute ethanol solution for later use. When using, take out the glass slide and dry it under argon for use.

[0036] S2. Use the physical vapor deposition electron beam evaporation method to deposit a vacuum thin film. Place the substrate on the substrate of the electron beam evaporation equipment and fix it. Pump the vacuum degree in the equipment cavity to 10e -4 Next, slowly adjust the gun filament beam current to 1.2 A, adjust the position of the electron beam spot to the center of the crucible, adjust the electron gun beam current to 70 A, and perform a melting and evaporation treatment on the TiO2 target. The film deposition rate is stable at After that, open the substrate baffle and deposit a 100 nm TiO2 layer on the substrate surface; then adjust the gun filament beam current to 0 A, replace the crucible target with an Ag target, adjust the gun filament beam current to 1.2 A again, adjust the position of the electron beam spot to the center of the crucible, adjust the electron gun beam current to 50 A, and the film deposition rate is stable at After that, deposit a 20 nm Ag layer on the TiO2 layer; adjust the size of the gun filament beam current to 0 A again, replace the crucible target with a TiO2 target, then adjust the gun filament beam current to 1.2 A, adjust the electron gun beam current to 70 A, and the film deposition rate is stable at Deposit a 20 nm TiO2 thin film layer on the Ag layer, and the electron beam evaporation of the thin film is completed.

[0037] S3. Sputter Au nanoparticles on the deposited TiO2 / Ag / TiO2 film by magnetron sputtering. When magnetron sputtering the Au target, the excitation current is 25 mA and the sputtering time is 20 s; the thickness of the Au nanoparticle layer is 10 nm.

[0038] Example 2

[0039] A preparation method of a TiO2 / Ag / TiO2 supported Au nanoparticle composite photothermal catalytic material, comprising the following steps:

[0040] S1. First, cut the glass slide into a 20×25 mm glass slide, clean the glass slide, ultrasonically clean the glass slide in soapy water and deionized water for 10 minutes in sequence, then rinse it 3 times with deionized water, and then ultrasonically clean it in acetone and absolute ethanol for 15 minutes. Store the cleaned glass slide in an absolute ethanol solution for later use. When using, take out the glass slide and dry it under argon for use.

[0041] S2. Use the physical vapor deposition electron beam evaporation method to deposit a vacuum thin film. Place the substrate on the substrate of the electron beam evaporation equipment and fix it. Pump the vacuum degree in the equipment cavity to 10e -4 Next, adjust the gun filament beam current to 1 A, adjust the position of the electron beam spot to the center of the crucible, adjust the electron gun beam current to 60 A, and perform a melting and evaporation treatment on the TiO2 target. The film deposition rate is stable at After that, open the substrate baffle and deposit a 120-nm TiO2 layer on the surface of the substrate. Then, adjust the gun filament beam current to 0 A, replace the crucible target with an Ag target, adjust the gun filament beam current to 1.2 A again, adjust the position of the electron beam spot to the center of the crucible, adjust the electron gun beam current to 35 A, and the film deposition rate is stable at After that, deposit a 25-nm Ag layer on the TiO2 layer. Once again, adjust the size of the gun filament beam current to 0 A. After replacing the crucible target with a TiO2 target, adjust the gun filament beam current to 1 A, adjust the electron gun beam current to 45 A, and the film deposition rate is stable at Deposit a 15-nm TiO2 material layer on the Ag layer, and the electron beam evaporation thin film is completed.

[0042] S3. Sputter Au nanoparticles on the deposited TiO2 / Ag / TiO2 film by magnetron sputtering. When magnetron sputtering the Au target, the excitation current is 30 mA, the sputtering time is 5 s, and the thickness of the Au nanoparticle layer is 2.5 nm.

[0043] Example 3

[0044] A preparation method of a TiO2 / Ag / TiO2-supported Au nanoparticle composite photothermal catalytic material, comprising the following steps:

[0045] S1. First, cut the glass slide into a 2×2 cm glass slide, clean the glass slide, ultrasonically clean the glass slide in soapy water and deionized water for 10 minutes in sequence, then rinse it 3 times with deionized water, ultrasonically clean it in acetone and absolute ethanol for 15 minutes in sequence, store the cleaned glass slide in an absolute ethanol solution for later use, take out the glass slide when in use, and dry it under argon for use.

[0046] S2. Use the physical vapor deposition electron beam evaporation method to deposit a vacuum thin film. Place the substrate on the substrate of the electron beam evaporation equipment and fix it. Pump the vacuum degree in the equipment cavity to 10e -4 Next, adjust the gun filament beam current to 1.1 A, adjust the position of the electron beam spot to the center of the crucible, adjust the electron gun beam current to 50 A, and perform a melting and evaporation treatment on the TiO2 target. The film deposition rate is stable at After that, open the substrate baffle and deposit a 110-nm TiO2 layer on the substrate surface; then adjust the gun filament beam current to 0 A, replace the crucible target with an Ag target, adjust the gun filament beam current to 1 A again, adjust the electron beam spot position to the center of the crucible, and adjust the electron gun beam current to 40 A. The coating rate is stabilized at After that, deposit an Ag layer of about 23 nm on the TiO2 layer; adjust the gun filament beam current to 0 A again, replace the crucible target with a TiO2 target, adjust the gun filament beam current to 1.1 A, and adjust the electron gun beam current to 60 A. The coating rate is stabilized at Deposit a layer of TiO2 material of about 15 nm on the Ag layer to complete the electron beam evaporation of the thin film.

[0047] S3. Sputter Au nanoparticles on the deposited TiO2 / Ag / TiO2 film by magnetron sputtering. When magnetron sputtering the Au target, the excitation current is 20 mA, the sputtering time is 3 s, and the thickness of the Au nanoparticle layer is 1.5 nm.

[0048] Example 4

[0049] A preparation method of a TiO2 / Ag / TiO2-supported Au nanoparticle composite photothermal catalytic material includes the following steps:

[0050] S1. First, cut the glass slide into a 20×25-mm glass slide, clean the glass slide, ultrasonically clean the glass slide in soapy water and deionized water for 10 minutes in sequence, rinse it with deionized water three times, ultrasonically clean it in acetone and absolute ethanol for 15 minutes in sequence, store the cleaned glass slide in an absolute ethanol solution for standby, take out the glass slide when in use, and dry it under argon for use.

[0051] S2. Adopt the physical vapor deposition electron beam evaporation method to deposit a vacuum thin film. Place the substrate on the substrate of the electron beam evaporation equipment and fix it. Pump the vacuum degree in the equipment cavity to 10e -4 Next, adjust the gun filament beam current to 1.1 A, adjust the electron beam spot position to the center of the crucible, adjust the electron gun beam current to 65 A, and perform a melting and evaporation treatment on the TiO2 target. The coating rate is stabilized at After that, open the substrate baffle and deposit a 100-nm TiO2 layer on the substrate surface; then adjust the gun filament beam to 0 A, replace the crucible target with an Ag target, adjust the gun filament beam current to 1.1 A again, adjust the electron beam spot position to the center of the crucible, and adjust the electron gun beam current to 45 A. The coating rate is stabilized at After that, a 20-nm Ag layer was evaporated onto the TiO2 layer; the beam current of the gun filament was adjusted to 0 A again. After replacing the crucible target with a TiO2 target, the beam current of the gun filament was adjusted to 1.1 A, and the beam current of the electron gun was adjusted to 65 A. The film deposition rate was stabilized at A 20-nm TiO2 material layer was evaporated onto the Ag layer, and the electron beam evaporation of the film was completed.

[0052] S3. Au nanoparticles were sputtered on the evaporated TiO2 / Ag / TiO2 film by magnetron sputtering. When magnetron sputtering the Au target, the excitation current was 28 mA, the sputtering time was 15 s, and the thickness of the Au nanoparticle layer was 7.5 nm.

[0053] Comparative Example 1

[0054] A TiO2 / Ag / TiO2 catalyst was prepared in the same way as in Example 1, except that there was no step S3, that is, there was no Au nanoparticle layer.

[0055] Comparative Example 2

[0056] A preparation method of a TiO2 / Ag catalyst includes the following steps: S1. First, the glass slide was cut into a 2×2 cm glass slide, and the glass slide was cleaned. The glass slide was ultrasonically cleaned in soapy water and deionized water for 10 minutes in sequence, then rinsed 3 times with deionized water, and then ultrasonically cleaned in acetone and absolute ethanol for 15 minutes in sequence. The cleaned glass slide was stored in an absolute ethanol solution for standby. When in use, the glass slide was taken out and dried under argon before use.

[0057] S2. Physical vapor deposition electron beam evaporation was used for vacuum film deposition. The substrate was placed and fixed on the substrate of the electron beam evaporation equipment, and the vacuum degree in the equipment cavity was pumped to 10e -4 Next, the beam current of the gun filament was adjusted to 1.2 A, the position of the electron beam spot was adjusted to the center of the crucible, the beam current of the electron gun was adjusted to 70 A, and the TiO2 target was melted and evaporated. The film deposition rate was stabilized at After that, the substrate baffle was opened, and a 100-nm TiO2 layer was evaporated on the substrate surface; then the beam current of the gun filament was adjusted to 0 A, the crucible target was replaced with an Ag target, the beam current of the gun filament was adjusted to 1.2 A again, the position of the electron beam spot was adjusted to the center of the crucible, the beam current of the electron gun was adjusted to 50 A, and the film deposition rate was stabilized at After that, a 20-nm Ag layer was evaporated onto the TiO2 layer.

[0058] The products obtained in Example 2 and Comparative Example 1 were photographed under a scanning electron microscope, and the results were as Figure 2As shown in the figure, (a) (b) is the TiO2 layer of the sample. It can be seen that the TiO2 film layer evaporated by electron beam is a dense film layer of particle cluster type. Figure (c) is the SEM image of the sample TiO2 / Ag / TiO2, and Figure (d) (e) are SEM images of the product of Example 2, wherein the spherical particles on the surface in the figure are sputtered Au nanoparticles, and Figure (f) (g) (h) (i) are the elemental analysis diagrams of Figure (e). The photocatalytic production of hydrogen peroxide was carried out using TiO2, the catalysts in Examples 1-4 and Comparative Examples 1-2. A 400W xenon lamp was used to measure the photocatalytic activity in the experiment. The hydrogen peroxide production experiment was carried out in a multi-position control box. The prepared photocatalytic material was placed in a 50ml isopropanol solution with a volume fraction of 10%. O2 was stirred in the dark for 30 minutes to establish a desorption-adsorption equilibrium. The light was turned on and the photocatalytic experiment was carried out under the xenon lamp. Samples were taken every 15 minutes. The photocatalytic production of H2O2 was measured by iodine titration. 1ml of 0.1mol / L potassium hydrogen phthalate (C8H5KWO4) aqueous solution and 1ml of 0.4mol / L potassium iodide (KI) aqueous solution were added to the sample and left for 30 minutes for color development. H2O2 molecules react with water under acidic conditions (H2O2+3I - +2H + →I 3- +2H2O) produces triiodide anion (I 3- ). According to the absorbance at 350nm, the I 3- The amount of H2O2 produced in each reaction process is estimated from the amount of H2O2 produced in each reaction process. Figure 3 As shown, Figure 3 The photocatalytic performance of different photocatalyst samples under visible light irradiation for a certain period of time was compared. Among them, TiO2 showed a certain catalytic activity under visible light irradiation, and the content of H2O2 produced was about 40umol / (L·h). This may be due to the hydrogen peroxide produced by the photocatalytic performance of TiO2 itself. Among them, the sample with the largest amount of H2O2 production was the catalyst in Example 2, which shows that the presence of Au can increase the production of hydrogen peroxide produced by the sample. At the same time, the results in the figure show that when the Au content is high, the plasmon effect will be significantly enhanced, the photothermal effect will be obvious, and when the photothermal effect is obvious, H2O2 will decompose. Therefore, the thickness of the Au nanoparticle layer is limited. If the Au nanoparticle layer is too thick, it will affect the effect of the catalyst.

[0059] The degradation experiment of rhodamine was carried out using the catalysts in Examples 1-4 and Comparative Example 1. First, 50 ml of 10 mg / L rhodamine solution was added to a quartz tube, and the prepared sample was placed into the quartz tube. The photocatalytic degradation experiment of rhodamine was carried out in a 400W xenon lamp multi-position control box. First, the dark reaction was carried out for 30 minutes to establish the desorption-adsorption equilibrium. Then the lamp was turned on. After the lamp was turned on, the reaction solution was taken every 30 minutes, and the degradation reaction performance was evaluated using a UV-visible spectrophotometer. The evaluation results are as Figure 4 shown. After 180 minutes of degradation by the product TiO2 / Ag / TiO2 in Comparative Example 1, the degradation effect was 40%. The degradation effect of the catalyst in Example 2 was 60%. This indicates that after introducing Au nanoparticles, the photocatalytic activity of the composite material was significantly enhanced, proving that it is not the Au nanoparticles on the surface that play the main role, but the surface plasmon between Au and Ag, resulting in an increase in hot spots and an improvement in the degradation effect. The figure also shows that when the thickness of the Au nanoparticle layer exceeds the limit, since Au occupies the active sites on the surface of TiO2 and may cover a part of TiO2, the photocatalytic performance decreases.

[0060] The above experiments show that after introducing Au nanoparticles into the catalyst of the present invention, the catalytic reaction effect can be improved.

[0061] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0062] In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application. Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A composite photothermal catalytic material of TiO2 / Ag / TiO2 loaded with Au nanoparticles, characterized in that: The invention comprises a substrate, wherein a TiO2 layer, an Ag layer, a TiO2 film layer and an Au nano-particle layer are arranged in sequence on the upper surface of the substrate from bottom to top.

2. The composite photothermal catalytic material of TiO2 / Ag / TiO2 loaded with Au nanoparticles according to claim 1, characterized in that: The thickness of the TiO2 layer is 100-120nm, the thickness of the Ag layer is 20-25nm, the thickness of the TiO2 thin film layer is 15-25nm, and the thickness of the Au nanoparticle layer is 1.5-10nm.

3. The composite photothermal catalytic material of TiO2 / Ag / TiO2 loaded with Au nanoparticles according to claim 2, characterized in that: The thickness of the TiO2 layer is 100 nm, the thickness of the Ag layer is 20 nm, the thickness of the TiO2 thin film layer is 20 nm, and the thickness of the Au nanoparticle layer is 2.5 nm.

4. The composite photothermal catalytic material of TiO2 / Ag / TiO2 loaded with Au nanoparticles according to claim 3, characterized in that: The substrate is a glass slide, a PVA water-soluble film or a K9 glass.

5. The method for preparing a composite photothermal catalytic material of TiO2 / Ag / TiO2 loaded with Au nanoparticles according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Place the substrate on the base plate of the electron beam evaporation equipment and fix it, place the TiO2 target crucible, and draw the vacuum degree in the equipment cavity to 10e -4 Below, the gun filament beam current is adjusted to 1-1.2A, the electron gun spot is adjusted to the center of the crucible, the electron gun beam current is adjusted to 50-70A, the TiO2 target is melted and evaporated, and the coating rate is stabilized at Afterwards, the substrate baffle is opened to evaporate a TiO2 layer on the substrate surface; Then adjust the gun filament beam current to 0A, replace with Ag target, adjust the gun filament beam current to 1-1.2A, adjust the electron gun beam current to 35-50A, and stabilize the coating rate at Afterwards, an Ag layer is evaporated on the TiO2 layer; Adjust the gun filament beam current to 0A again, replace the target material with TiO2 target material, adjust the gun filament beam current to 1-1.2A, and the electron gun beam current to 50-70A. The coating rate is stable at A TiO2 thin film layer is evaporated on the Ag layer; S2. Au nanoparticles are sputtered on the evaporated TiO2 thin film layer by magnetron sputtering. When magnetron sputtering Au target material, the excitation current is 20-30 mA and the sputtering time is 3-20 s.

6. The method for preparing a composite photothermal catalytic material of TiO2 / Ag / TiO2 loaded with Au nanoparticles according to claim 5, characterized in that: When the TiO2 layer is evaporated in S1, the gun filament beam current is 1.2A; the electron gun beam current is 70A, and the coating rate is When evaporating the Ag layer, the gun filament beam current is 1.2A, the electron gun beam current is 45A, and the coating rate is When evaporating the TiO2 thin film layer, the gun filament beam current is 1.2A, the electron gun beam current is 70A, and the coating rate is 7. The method for preparing a composite photothermal catalytic material of TiO2 / Ag / TiO2 loaded with Au nanoparticles according to claim 6, characterized in that: In S2, the excitation current is 25 mA and the sputtering time is 5 s during magnetron sputtering of Au target.

8. The method for preparing a composite photothermal catalytic material of TiO2 / Ag / TiO2 loaded with Au nanoparticles according to claim 7, characterized in that: The substrate is a glass slide. The glass slide is ultrasonically cleaned in soap water and deionized water for 10 minutes, rinsed with deionized water for 3 times, and then ultrasonically cleaned in acetone and anhydrous ethanol for 15 minutes. The cleaned glass slide is stored in anhydrous ethanol solution for standby use. When used, the glass slide is taken out and blown dry under argon gas.

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