Preparation method and application of nano photo-thermal and photocatalytic Ag / ZnO composite material

Abstract

The invention provides a preparation method of a nano photo-thermal and photocatalytic Ag / ZnO composite material, which specifically comprises the following steps: preparing a silver nitrate solution, adding a pre-prepared MOFs (Metal-Organic Frameworks) material with Zn as a metal framework into the silver nitrate solution, stirring and adsorbing; 3, centrifugally separating the mixture obtained in the step 2, washing with deionized water, and drying or freeze-drying in a drying box to obtain a dried solid; and calcining the solid obtained by drying in the step 3 in a muffle furnace to obtain the nano photo-thermal and photocatalytic Ag / ZnO composite material. According to the nano photo-thermal and photocatalytic Ag / ZnO composite material prepared by the method, not only are the photo-thermal performance and photocatalytic performance of the Ag / ZnO composite material improved, but also the problem that the Ag / ZnO composite material in the prior art cannot reach the nanoscale during preparation is solved.

Description

Technical Field

[0001] The present invention belongs to the field of photocatalytic materials, and in particular relates to a method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material. Background Art

[0002] Bacterial infections are one of the greatest threats to human health worldwide. Simultaneously, antibiotic resistance has significantly increased due to the overuse of antibiotics. There is an urgent need to explore new antibiotic-free strategies to combat the rapidly evolving antimicrobial resistance. Photothermal therapy (PTT) is widely recognized as an effective approach to inhibit bacterial proliferation and mitigate antibiotic resistance. The principle of PTT is to exploit the vulnerability of common pathogens to low temperatures and employ localized heating as a means of combating bacterial infections. Zinc oxide nanoparticles (ZnO) have been extensively studied due to their physical, chemical, and ease of synthesis advantages. They also possess advantages such as chemical stability, safety, nontoxicity, and strong biocompatibility. However, the wide band gap (3.37 eV), significant exciton binding energy (approximately 60 MeV), low charge separation efficiency, and rapid recombination rate of ZnO nanoparticles (NPs) limit their absorption capacity within the visible light spectrum. Furthermore, the propensity for the formation of surface defects in ZnO leads to nonradiative recombination, which limits its photothermal conversion efficiency. The photothermal properties of ZnO can be enhanced by the incorporation of precious metals such as gold and silver. As a wide-bandgap semiconductor material, ZnO exhibits excellent photocatalytic activity under ultraviolet irradiation. However, the photogenerated electron-hole pairs in ZnO easily recombine, which greatly reduces the photocatalytic efficiency of ZnO.

[0003] In order to improve the photothermal or photocatalytic properties of ZnO materials, many methods for synthesizing Ag / ZnO nanocomposites have been reported. However, in the existing technologies reported so far, the preparation of Ag / ZnO composites has the following problems: 1) the material has a single function and cannot have both photothermal antibacterial and photocatalytic functions; 2) it cannot reach the nanoscale; 3) there is the problem of Ag agglomeration; 4) Ag cannot be well dispersed on ZnO. Summary of the Invention

[0004] The purpose of the present invention is to propose a method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material. By this method, the nano-photothermal and photocatalytic Ag / ZnO composite material is prepared, which improves the photothermal and photocatalytic properties of the Ag / ZnO composite material and solves the problem of single function of the existing technology.

[0005] The technical solution of the present invention is achieved as follows:

[0006] The present invention provides a method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material, comprising:

[0007] The nano-photothermal and photocatalytic Ag / ZnO composite material is prepared by chemical reaction of MOFs material with Zn as a metal skeleton and silver nitrate solution.

[0008] Further, the method specifically includes the following steps:

[0009] Step 1: Prepare a silver nitrate solution, add the pre-prepared MOFs material with Zn as the metal skeleton into the silver nitrate solution, and stir for adsorption;

[0010] Step 2: centrifuging the mixture obtained in step 1, washing with deionized water, and then drying in a drying oven or freeze-drying to obtain a dried solid;

[0011] Step 3: The solid obtained by drying in step 2 is placed in a Maffei furnace and calcined to obtain a nano-photothermal and photocatalytic Ag / ZnO composite material.

[0012] Furthermore, the solvent used in the silver nitrate solution can be DMF (N,N-dimethylformamide), methanol or water.

[0013] Furthermore, the MOFs material with Zn as the metal skeleton may be MOF-5 or ZIF-8.

[0014] Furthermore, in step 1, the adsorption is stirred for 0.5-2 hours.

[0015] Furthermore, the mass ratio of the MOFs material to silver nitrate is between 1000:1 and 1:1.

[0016] Furthermore, in step 2, washing is performed with deionized water 2-3 times.

[0017] Furthermore, in step 2, the temperature of the drying oven is 80-120°C.

[0018] Furthermore, the calcination temperature is between 400-600° C., and the calcination time is 1-4 hours.

[0019] The present invention also provides an application of a nano-photothermal and photocatalytic Ag / ZnO composite material. The Ag / ZnO composite material is applied to the field of photothermal nano-antibacterial and / or photocatalytic degradation, and the Ag ion adsorption concentration can be in the range of 0.01 to 0.075 mol / L.

[0020] The present invention has the following beneficial effects:

[0021] 1. This invention proposes a method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material. This method improves the photothermal and photocatalytic properties of the Ag / ZnO composite material, resolving the single-function issue of existing technologies. The Ag / ZnO composite material prepared by this invention exhibits both photothermal and antibacterial properties as well as photocatalysis.

[0022] 2. The embodiment of the present invention prepares nano-photothermal and photocatalytic Ag / ZnO composite materials, develops the application field of MOFs materials, and realizes the dual application of high-value-added antibacterial materials and photocatalytic materials.

[0023] 3. The embodiments of the present invention solve the problem that the Ag / ZnO composite material in the prior art cannot be prepared at the nanoscale, and solve the problem of Ag agglomeration, thereby dispersing Ag well on ZnO.

[0024] 4. The embodiments of the present invention broaden the scope of application of MOFs materials, contribute new materials to the fields of photothermal nano-antibacterial and photocatalytic degradation, and are in line with the country's direction for the development of new pharmaceutical and environmental materials.

[0025] 5. The embodiment of the present invention uses MOF material as a template, adsorbs Ag ions and then calcines. The pores of the MOF material can well confine Ag ions, so that Ag will not agglomerate during the calcination process, and is well dispersed on the ZnO particles, thereby enhancing the Schottky barrier, thereby promoting the separation of photogenerated charges and improving the photothermal and photocatalytic properties of the material.

[0026] 6. In the embodiment of the present invention, the particle size of the ZnO particles obtained using the MOF material as a template is controlled between 50nm and 200nm, which is difficult to achieve with other preparation methods. The small particle size can increase the specific surface area of the material, thereby enhancing the performance of the material.

[0027] 7. The preparation method of the embodiment of the present invention is simple and easy, and the solvent is easy to recover. Whether it is prepared in the laboratory or scaled up to industrial production, the process is not difficult, and the required equipment is simple and cheap.

[0028] 8. The embodiment of the present invention is a method for preparing a nanometer dual-functional Ag / ZnO composite material with simple process, safe and reliable product performance, nanometer-level product particle size, uniform distribution and good consistency, and suitable for industrial production.

[0029] 9. This embodiment of the present invention provides a simple method for synthesizing Ag / ZnO composite materials, using MOF-5 and other materials as templates to prepare silver-doped composite metal oxide nanomaterials. The Ag / ZnO composite material's strong absorption in the visible light region and ability to generate heat under irradiation make it a potential antibacterial agent and photothermal material. It also exhibits excellent photocatalytic degradation of organic pollutants under ultraviolet light. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 These are the SEM and MAPing images of MOF-5-derived Ag / ZnO (0.05 mol / L) in the examples of the present invention.

[0032] Figure 2 This is the TEM image of Ag / ZnO (0.05 mol / L) in an embodiment of the present invention.

[0033] Figure 3 : This is the XRD diffraction pattern of Ag / ZnO in the embodiment of the present invention.

[0034] Figure 4 This is the XPS spectrum of the Ag / ZnO composite material in the embodiment of the present invention.

[0035] Figure 5 SEM and TEM images;

[0036] Figure 5 A is the SEM image of pure ZnO, Figure 5 B is the SEM image of Ag / ZnO (0.025 mol / L) in the embodiment of the present invention. Figure 5 C and Figure 5 D is a TEM image of Ag / ZnO (0.025 mol / L) in an example of the present invention.

[0037] Figure 6 Comparison of the sterilization test effects of the embodiments of the present invention and pure ZnO: (A and B) colony photos (A and C) and (B and D) bacterial survival rates of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) under near-infrared irradiation of Ag / ZnO (0-250 μg / mL) for 5 minutes.

[0038] Figure 7Graph showing the experimental results of photocatalytic degradation of methyl orange by Ag / ZnO with different Ag concentrations in an embodiment of the present invention.

[0039] Figure 8 This is a graph showing the photocatalytic cycle experimental results of Ag / ZnO (0.025 mol / L) in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0041] In the embodiment of the present invention, p-type conductive zinc oxide can be synthesized by doping with transition metals, and the surface energy level of ZnO nanoparticles can be adjusted through the plasma effect of silver (Ag), thereby improving the photothermal performance of the ZnO nanoparticles.

[0042] The experimental results show that ZnO nanoparticles modified with precious metal Ag can form a Schottky barrier, thereby promoting the separation of photogenerated charges and thus improving the photocatalytic activity of the material.

[0043] The inventors of the present application have found that the smaller the particle size, the better the antibacterial and photocatalytic activity. Reducing the particle size can increase the specific surface area of the particles, thereby improving the photocatalytic efficiency of ZnO. Metal-organic frameworks (MOFs) have high surface area, adjustable pore size and multiple functions. The present application uses metal-organic frameworks (MOFs) as templates for the synthesis of metal and metal oxide composites. As a template, the metal-organic framework (MOF) can accommodate single or multiple types of inorganic centers, which are subsequently decomposed to form high surface area monodisperse nanoparticles supported by MOF fragments.

[0044] The present invention provides a method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material, comprising the following steps:

[0045] Step 1: DMF (N,N-dimethylformamide), methanol or water can be used as a solvent to prepare a silver nitrate solution, and the pre-prepared MOFs material with Zn as the metal skeleton is added to the silver nitrate solution and stirred for adsorption for 0.5-2 hours;

[0046] The mass ratio of MOFs material to silver nitrate is between 1000:1 and 1:1;

[0047] MOFs is the abbreviation of metal organic framework compounds. MOFs materials can be MOF-5 or ZIF-8;

[0048] Step 2: centrifuging the mixture obtained in step 1, washing it with deionized water 2-3 times, and then drying it in a drying oven at a temperature of 80-120° C. or freeze-drying it to obtain a dried solid;

[0049] Step 3: The solid obtained by drying in step 2 is placed in a Maffei furnace and calcined at a temperature between 400-600° C. for 1-4 hours to obtain a nano-photothermal and photocatalytic Ag / ZnO composite material.

[0050] An embodiment of the present invention also provides an application of a nano-photothermal and photocatalytic Ag / ZnO composite material, wherein the Ag / ZnO composite material is applied to the field of photothermal nano-antibacterial and / or photocatalytic degradation, and the Ag ion adsorption concentration can be in the range of 0.01 to 0.075 mol / L.

[0051] The following are specific embodiments

[0052] Example 1:

[0053] Example 1 provides a method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material, comprising the following steps:

[0054] Step 1: Prepare a silver nitrate solution with a concentration of 0.025 mol / L (solvent: DMF), add the prepared MOF-5 to the solution, and stir and adsorb for 1 hour. The mass ratio of MOF-5 material to silver nitrate is 4.7.

[0055] Step 2: The mixture was centrifuged and washed twice with deionized water, and then dried in a drying oven (temperature 100° C.) for 2 h.

[0056] Step 3: The dried solid was placed in a Maffei furnace and calcined at a temperature of 500° C. for 2 h to obtain a nano-photothermal and photocatalytic Ag / ZnO composite material product (hereinafter referred to as: Ag / ZnO).

[0057] By 808 nm laser irradiation (2 W / cm 2 ) to evaluate the photothermal performance of Ag / ZnO in Example 1. The results show that the temperature change of the aqueous solution of the material is 500μg / mL, and the temperature rise reaches 38.7℃ after 5 minutes of irradiation. When the concentration of Ag / ZnO is 200μg / mL, the 808nm laser (2W / cm 2 ) for 5 min, the bactericidal effect against Staphylococcus aureus and Escherichia coli reached 100%, while the bactericidal rates of pure ZnO at the same concentration (200 μg / mL) against Staphylococcus aureus and Escherichia coli were only 64% and 46%, respectively.

[0058] The photocatalytic activity of Ag / ZnO towards methyl orange dye was investigated using a 250W UV lamp (wavelength, 365nm). 0.01g of the photocatalyst was added to 50mL of a 20ppm aqueous solution of methyl orange. The solution was stirred in the dark for 30 minutes to achieve absorption-desorption equilibrium between the photocatalyst and the methyl orange solution. Subsequently, after 120 minutes of UV irradiation, the Ag / ZnO sample exhibited a photocatalytic degradation efficiency of nearly 100%.

[0059] Example 2:

[0060] Example 2 provides a method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material, comprising the following steps:

[0061] Step 1: Prepare a silver nitrate solution with a concentration of 0.05 mol / L (solvent: DMF), add the prepared MOF-5 to the solution, and stir and adsorb for 1 hour. The mass ratio of MOF-5 material to silver nitrate is 2.4.

[0062] Step 2: The mixture was centrifuged and washed twice with deionized water, and then dried in a drying oven (temperature 100° C.) for 2 h.

[0063] Step 3: The dried solid was placed in a Maffei furnace and calcined at a temperature of 500° C. for 2 h to obtain a nano-photothermal and photocatalytic Ag / ZnO composite material product (hereinafter referred to as: Ag / ZnO).

[0064] By 808 nm laser irradiation (2 W / cm 2 ) to evaluate the photothermal performance of Ag / ZnO in Example 2. The results show that when the concentration of the aqueous solution of the material is 500 μg / mL, the temperature rise reaches 30°C after 5 minutes of irradiation. When the concentration of Ag / ZnO is 200 μg / mL and the 808 nm laser (2 W / cm 2 ) When irradiated for 5 minutes, the bactericidal effect on Staphylococcus aureus and Escherichia coli reached 90%.

[0065] The photocatalytic activity of Ag / ZnO towards methyl orange dye was investigated using a 250W UV lamp (wavelength 365nm). 0.01g of the photocatalyst was added to 50mL of a 20ppm aqueous solution of methyl orange. The solution was stirred in the dark for 30 minutes to achieve absorption-desorption equilibrium between the photocatalyst and the methyl orange solution. Subsequently, after 120 minutes of UV irradiation, the Ag / ZnO sample exhibited a photodegradation efficiency of 95%.

[0066] Example 3:

[0067] Example 3 provides a method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material, comprising the following steps:

[0068] Step 1: Prepare a silver nitrate solution with a concentration of 0.025 mol / L (the solvent is methanol), add the prepared ZIF-8 to the above solution, and stir and adsorb for 1 hour, wherein the mass ratio of ZIF-8 material to silver nitrate is 2.4.

[0069] Step 2: The mixture was centrifuged and washed twice with deionized water, and then dried in a drying oven (temperature 80° C.) for 3 h.

[0070] Step 3: The dried solid was placed in a Maffei furnace and calcined at a temperature of 500° C. for 2 h to obtain a nano-photothermal and photocatalytic Ag / ZnO composite material product (hereinafter referred to as: Ag / ZnO).

[0071] By 808 nm laser irradiation (2 W / cm 2 ) to evaluate the photothermal performance of Ag / ZnO in Example 3. The results show that when the concentration of the aqueous solution of the material is 500 μg / mL, the temperature rise reaches 30°C after 5 minutes of irradiation. When the concentration of Ag / ZnO is 200 μg / mL and the 808 nm laser (2 W / cm 2 ) When irradiated for 5 minutes, the bactericidal effect on Staphylococcus aureus and Escherichia coli reached 98%.

[0072] The photocatalytic activity of Ag / ZnO towards methyl orange dye was investigated using a 250W UV lamp (wavelength 365nm). 0.01g of the photocatalyst was added to 50mL of a 20ppm aqueous solution of methyl orange. The solution was stirred in the dark for 30 minutes to achieve absorption-desorption equilibrium between the photocatalyst and the methyl orange solution. Subsequently, after 120 minutes of UV irradiation, the Ag / ZnO sample exhibited a photodegradation efficiency of 98%.

[0073] Example 4:

[0074] Example 4 provides a method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material, comprising the following steps:

[0075] Step 1: Prepare a silver nitrate solution with a concentration of 0.025 mol / L (solvent: DMF), add the prepared MOF-5 to the solution, and stir and adsorb for 0.5 h. The mass ratio of MOF-5 material to silver nitrate is 4.7.

[0076] Step 2: The mixture was centrifuged and washed twice with deionized water, and then freeze-dried.

[0077] Step 3: The dried solid was placed in a Maffei furnace and calcined at a temperature of 500° C. for 2 h to obtain a nano-photothermal and photocatalytic Ag / ZnO composite material product (hereinafter referred to as: Ag / ZnO).

[0078] By 808 nm laser irradiation (2 W / cm 2 ) to evaluate the photothermal performance of Ag / ZnO in Example 4. The results show that the temperature change of the aqueous solution of the material is 500μg / mL, and the temperature rise reaches 37.1℃ after 5 minutes of irradiation. When the concentration of Ag / ZnO is 200μg / mL, the 808nm laser (2W / cm 2 ) When irradiated for 5 minutes, the bactericidal effect on Staphylococcus aureus and Escherichia coli reached 100%.

[0079] The photocatalytic activity of Ag / ZnO towards methyl orange dye was investigated using a 250W UV lamp (wavelength 365nm). 0.01g of the photocatalyst was added to 50mL of a 20ppm aqueous solution of methyl orange. The solution was stirred in the dark for 30 minutes to achieve absorption-desorption equilibrium between the photocatalyst and the methyl orange solution. Subsequently, after 120 minutes of UV irradiation, the Ag / ZnO sample exhibited a photodegradation efficiency of 99%.

[0080] Example 5:

[0081] Example 5 provides a method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material, comprising the following steps:

[0082] Step 1: Prepare a silver nitrate solution with a concentration of 0.0001 mol / L (solvent: DMF), add the prepared MOF-5 to the solution, and stir and adsorb for 1 hour. The mass ratio of MOF-5 material to silver nitrate is 1000.

[0083] Step 2: The mixture was centrifuged and washed twice with deionized water, and then dried in a drying oven (temperature 100° C.) for 2 h.

[0084] Step 3: The dried solid was placed in a Maffei furnace and calcined at a temperature of 500° C. for 2 h to obtain a nano-photothermal and photocatalytic Ag / ZnO composite material product (hereinafter referred to as: Ag / ZnO).

[0085] By 808 nm laser irradiation (2 W / cm 2 ) to evaluate the photothermal performance of Ag / ZnO in Example 5. The results show that the temperature change of the aqueous solution of the material is 500μg / mL, and the temperature rise reaches 28.7℃ after 5 minutes of irradiation. When the concentration of Ag / ZnO is 200μg / mL and the 808nm laser (2W / cm 2) When irradiated for 5 minutes, the bactericidal effect on Staphylococcus aureus and Escherichia coli reached 84%.

[0086] The photocatalytic activity of Ag / ZnO towards methyl orange dye was investigated using a 250W UV lamp (wavelength 365nm). 0.01g of the photocatalyst was added to 50mL of a 20ppm aqueous solution of methyl orange. The solution was stirred in the dark for 30 minutes to achieve absorption-desorption equilibrium between the photocatalyst and the methyl orange solution. Subsequently, after 120 minutes of UV irradiation, the Ag / ZnO sample exhibited a photodegradation efficiency of 86%.

[0087] It should be noted that Examples 1-5 were all calcined in air and were all carried out under normal pressure.

[0088] Comparative Example 1: The same as Example 1, except that: in Comparative Example 1, the MOF-5 material is first placed under nitrogen protection and calcined at high temperature (800° C.) for 5 h, and then the high-temperature calcined MOF-5 material is added to the silver nitrate solution.

[0089] Comparative Example 2: Preparation of Ag / ZnO composite material, the preparation method refers to CN106362742A.

[0090] Comparative Example 3: Preparation of Ag / ZnO composite material, the preparation method refers to CN108855076A.

[0091] Blank example: pure ZnO.

[0092] Experimental test (Example 1, Comparative Examples 1-3, and blank examples):

[0093] By 808 nm laser irradiation (2 W / cm 2 ) to evaluate the photothermal performance of Ag / ZnO in Example 1. The results show that the temperature change of the aqueous solution of the material is 500μg / mL, and the temperature rise reaches 38.7℃ after 5 minutes of irradiation. When the concentration of Ag / ZnO is 200μg / mL, the 808nm laser (2W / cm 2 ) When irradiated for 5 minutes, the bactericidal effect on Staphylococcus aureus and Escherichia coli reached 100%.

[0094] In the same experimental test, the sterilization rates of pure ZnO (blank case) at the same concentration (200 μg / mL) against Staphylococcus aureus and Escherichia coli were only 64% and 46%, respectively.

[0095] The sterilization rate of Ag / ZnO (Comparative Example 1) at the same concentration (200 μg / mL) against Staphylococcus aureus and Escherichia coli was 69%.

[0096] The sterilization rate of Ag / ZnO (Comparative Example 2) at the same concentration (200 μg / mL) against Staphylococcus aureus and Escherichia coli was 65%.

[0097] The sterilization rate of Ag / ZnO (Comparative Example 3) at the same concentration (200 μg / mL) against Staphylococcus aureus and Escherichia coli was 68%.

[0098] The photocatalytic activity of Ag / ZnO towards methyl orange dye was investigated using a 250W UV lamp (wavelength, 365nm). 0.01g of the photocatalyst was added to 50mL of a 20ppm aqueous solution of methyl orange. The solution was stirred in the dark for 30 minutes to achieve absorption-desorption equilibrium between the photocatalyst and the methyl orange solution. Subsequently, after 120 minutes of UV irradiation, the Ag / ZnO sample from Example 1 exhibited a photodegradation efficiency of nearly 100%.

[0099] Through the same experimental test, the photocatalytic degradation efficiency of the pure ZnO sample (blank example) after irradiation with ultraviolet light for 120 minutes was 55.8%.

[0100] The photodegradation efficiency of the Ag / ZnO (Comparative Example 1) photocatalyst after irradiation with ultraviolet light for 120 minutes was 95%.

[0101] The photodegradation efficiency of the Ag / ZnO (Comparative Example 2) photocatalyst after irradiation with ultraviolet light for 120 minutes was 83%.

[0102] The photodegradation efficiency of the Ag / ZnO (Comparative Example 3) photocatalyst after irradiation with ultraviolet light for 120 minutes was 88%.

[0103] Experimental results:

[0104]

[0105] According to the above table, it can be seen that the bactericidal rate and photodegradation efficiency of the Ag / ZnO composite materials prepared in Comparative Examples 2 and 3 are far inferior to those in Example 1 of the present invention; the photodegradation efficiency of Comparative Example 1 is slightly lower than that of Example 1 of the present invention, but its bactericidal efficiency is far lower than that of Example 1 of the present invention.

[0106] See also Figure 3, XRD diffraction pattern of Ag / ZnO. From the XRD pattern of Ag / ZnO, it can be seen that the diffraction peaks 2θ at 31.769°, 34.42°, 36.25°, 47.53°, 56.60°, 62.86°, 66.37°, 67.96°, 69.09°, 72.56° and 76.95° belong to the planes (100), (002), (101), (102), (110), (103), (200), (112), (201), (004) and (202) of ZnO (JCPDS 36-1451). The 2θ diffraction peaks at 38.11°, 44.27°, 64.42°, and 77.47° belong to the (111), (200), (220), and (311) planes of Ag (JCPDS 04-0783). Ag / ZnO is composed of silver (Ag) and zinc oxide (ZnO). As the concentration of adsorbed silver ions increases, the intensity of the characteristic silver peaks in the XRD spectrum becomes more pronounced.

[0107] See also Figure 4 The chemical state of Ag / ZnO was further characterized by XPS. Figure 4 The two peaks at 1021.8 eV and 1044.9 eV in d correspond to the binding energies of Zn 2p3 / 2 and Zn 2p1 / 2, respectively. Figure 4 b shows the XPS spectrum of c15. Figure 4 c is the XPS spectrum of Ag 3d. The peaks corresponding to Ag 3d5 / 2 and Ag 3d3 / 2 are located at 367.8 eV and 373.8 eV, respectively, indicating that Ag is doped in the Ag / ZnO layer in the form of metallic silver. This is consistent with the XRD results.

[0108] See also Figure 5 , SEM images of pure ZnO and composite Ag / ZnO (0.025mol / L) samples are shown in Figure 5 As shown in (A and B). Figure 5 As shown in Figure A, the pure ZnO obtained by calcining MOF-5 has a strip-like or irregular circular morphology with a particle size between 50 and 100 nm. The small grain size is due to the template effect of MOF-5. The morphology and particle size of Ag / ZnO obtained by calcining MOF-5 after Ag ion adsorption ( Figure 5 B) is almost indistinguishable from pure ZnO. This indicates that the addition of Ag does not change the crystal morphology of ZnO. High-resolution transmission electron microscopy (HRTEM) images are shown in Figure 2. Figure 5 (C and D) Figure 5 C shows that the morphology of Ag / ZnO particles is mainly spherical, with an average diameter of about 50nm. The interplanar spacing of ZnO along the (100) direction and Ag along the (220) direction are 0.281nm and 0.144nm, respectively. Figure 5 As shown in D.

[0109] See also Figure 6 To study the photothermal effect of 0.025 mol / L Ag / ZnO on Staphylococcus aureus and Escherichia coli, the bacteria were mixed with different concentrations of Ag / ZnO (100-200 μg / mL), irradiated with laser (808 nm, 2 W / cm2) for 5 min, and then cultured on agar plates at 37 °C for 24 h. The resulting colonies were imaged and counted ( Figure 6 AD). Figure 6 A and Figure 6 C shows that when the Ag / ZnO concentration increases from 100μg / mL to 200μg / mL, the bacterial activity decreases significantly. When the Ag / ZnO concentration is 200μg / mL and irradiated with 808nm laser (2W / cm2) for 5min, the bactericidal effect on Staphylococcus aureus and Escherichia coli reaches 100%, while the bactericidal rate of pure ZnO at the same concentration (200μg / mL) on Staphylococcus aureus and Escherichia coli is only 64% and 46% respectively. Figure 6 B and Figure 6 D). The results show that the incorporation of Ag significantly improves the bactericidal effect of the material, and the antibacterial performance gradually improves with the increase of Ag / ZnO concentration.

[0110] See also Figure 7 The concentration of methyl orange changes under ultraviolet irradiation as follows Figure 7 As shown, C0 is the initial concentration and C is the concentration at a certain reaction time t (min). When the Ag ion adsorption concentration is in the range of 0.01 to 0.075 mol / L, methyl orange is almost completely degraded within 120 minutes. This indicates that its photocatalytic activity is significantly enhanced compared to pure ZnO (the degradation rate of pure ZnO is 55.8%). Among all samples, 0.025 mol / L Ag / ZnO showed the most effective performance, with a degradation rate close to 100% at 100 minutes. When the Ag ion adsorption concentration is less than 0.001 mol / L or greater than 0.1 mol / L, the degradation rate is comparable to or lower than that of pure ZnO. This shows that too high or too low Ag ion adsorption concentration is not conducive to improving photocatalytic activity.

[0111] See also Figure 8 The stability of Ag / ZnO degradation of MO was evaluated under high pressure mercury lamp irradiation. Figure 8 As shown in Figure 3, after 4 cycles, the degradation efficiency of methyl orange over Ag / ZnO remained close to 100%, indicating that the catalyst has excellent stability.

[0112] From the above five examples, it can be concluded that the method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material provided by this application has the following innovations:

[0113] (1) A reasonable element ratio is adopted to reduce production costs. At the same time, the best matching of the performance of each component is achieved, and the composition is uniform and consistent.

[0114] (2) MOFs material was used as a template to make the material particle size reach the nanoscale, thereby improving the dispersion of Ag in the material and improving the photothermal and photocatalytic properties of the material.

[0115] (3) A simple process is adopted, all of which are carried out under normal pressure, with low equipment requirements, simple solvent recovery, and easy industrial production.

[0116] In summary, the present application is a method for preparing a nano-Ag / ZnO composite material with a simple process, safe and reliable product performance, uniform product particle size distribution and good consistency, and is suitable for industrial production.

[0117] 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 in the scope of protection of the present invention.

Claims

1. A method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material, characterized in that: The steps include: The nano-photothermal and photocatalytic Ag / ZnO composite material is prepared by chemical reaction of MOFs material with Zn as a metal skeleton and silver nitrate solution.

2. The method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material according to claim 1, characterized in that: The specific steps include: Step 1: Prepare a silver nitrate solution, add the pre-prepared MOFs material with Zn as the metal skeleton into the silver nitrate solution, and stir for adsorption; Step 2: centrifuging the mixture obtained in step 1, washing with deionized water, and then drying in a drying oven or freeze-drying to obtain a dried solid; Step 3: The solid obtained by drying in step 2 is placed in a Maffei furnace and calcined to obtain a nano-photothermal and photocatalytic Ag / ZnO composite material.

3. The method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material according to claim 2, characterized in that: The solvent used in the silver nitrate solution can be DMF, methanol or water.

4. The method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material according to claim 2, characterized in that: The MOFs material with Zn as the metal skeleton may be MOF-5 or ZIF-8.

5. The method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material according to claim 2, characterized in that: In the step 1, the adsorption is stirred for 0.5-2 hours.

6. The method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material according to claim 2, characterized in that: The mass ratio of the MOFs material to silver nitrate is between 1000:1 and 1:

1.

7. The method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material according to claim 2, characterized in that: In step 2, washing is performed with deionized water 2-3 times.

8. The method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material according to claim 2, characterized in that: In step 2, the temperature of the drying oven is 80-120°C.

9. The method for preparing a nano-photothermal and photocatalytic Ag / ZnO composite material according to claim 2, characterized in that: The calcination temperature is between 400-600° C., and the calcination time is 1-4 hours.

10. The use of a nano-photothermal and photocatalytic Ag / ZnO composite material according to claims 1-9, characterized in that: The Ag / ZnO composite material is applied to the field of photothermal nano-antibacterial and / or photocatalytic degradation, and the Ag ion adsorption concentration is in the range of 0.01 to 0.075 mol / L.

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