Silver palladium quantum dot anchoring defect titanium dioxide nanometer array composite photocatalyst and preparation method and application thereof

Abstract

The application belongs to the technical field of photocatalysis, and provides a silver-palladium quantum dot anchored defect titanium dioxide nanometer array composite photocatalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: anodizing a titanium sheet cathode and a titanium mesh anode in a fluorine-containing ethylene glycol solution to obtain an amorphous titanium dioxide nanometer array, annealing to obtain an anatase titanium dioxide nanometer array, cathodically reducing the titanium sheet anode and the anatase titanium dioxide nanometer array cathode in a formic acid solution to obtain a defect titanium dioxide nanometer array, and placing the defect titanium dioxide nanometer array in a Pd-Ag mixed solution, and adding a sodium borohydride solution dropwise to perform reaction. The composite photocatalyst with dual functions of degrading organic pollutants and killing microorganisms is prepared by adopting the secondary anodization + cathodic reduction + chemical reduction method, the degradation efficiency of the composite photocatalyst on tetracycline hydrochloride and ciprofloxacin is more than 5 times that of titanium dioxide, and the composite photocatalyst can completely inactivate escherichia coli and significantly inhibit staphylococcus albus.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photocatalysis, and particularly relates to a silver-palladium quantum dot anchored defect titanium dioxide nanometer array composite photocatalyst and a preparation method and application thereof. BACKGROUND

[0002] The rapid development of industrialization, urbanization and economic globalization has broken the ecological balance and exacerbated the pollution of the ecological environment, which seriously threatens the living environment and health of human beings. Among them, the problems of antibiotic resistance and the spread of pathogenic microorganisms are most prominent, therefore, the demand for multifunctional materials for the continuous degradation of antibiotics and the inhibition of the spread of pathogenic microorganisms is also more and more urgent.

[0003] Titanium dioxide nanomaterials are concerned due to their green environmental protection and low cost advantages, but due to their wide band gap, they only respond to ultraviolet light, which greatly limits their application in the field of photocatalysis. Many scholars have adopted strategies such as morphology control of titanium dioxide nanomaterials, construction of heterojunctions, semiconductor compounding and noble metal surface modification to improve the performance of titanium dioxide nanomaterials, but mainly focus on the removal of organic pollutants. However, actual wastewater treatment needs to consider both organic pollutants and microorganisms. At present, there is no research on dual-functional photocatalysts that can simultaneously remove organic pollutants and microorganisms. Therefore, it has good prospects to study dual-functional photocatalysts that can simultaneously remove organic pollutants and microorganisms. SUMMARY

[0004] The present application aims at the deficiencies of the prior art to provide a silver-palladium quantum dot anchored defect titanium dioxide nanometer array composite photocatalyst and a preparation method and application thereof.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0006] The present application provides a preparation method of a silver-palladium quantum dot anchored defect titanium dioxide nanometer array composite photocatalyst, comprising the following steps:

[0007] 1) Anodizing titanium sheet cathode and titanium mesh anode in a fluorine-containing ethylene glycol solution to obtain amorphous titanium dioxide nanometer array;

[0008] 2) Annealing the amorphous titanium dioxide nanometer array to obtain anatase titanium dioxide nanometer array;

[0009] 3) Taking titanium sheet as anode and anatase titanium dioxide nanometer array as cathode, and performing cathodic reduction of the anode and the cathode in a formic acid solution to obtain defect titanium dioxide nanometer array;

[0010] 4) under an argon atmosphere, placing the defective titanium dioxide nanometer array into the Pd-Ag mixed solution, and adding a sodium borohydride solution dropwise into the Pd-Ag mixed solution to react, so as to obtain the silver palladium quantum dot anchoring defective titanium dioxide nanometer array composite photocatalyst.

[0011] Preferably, the temperature of the anodization in step 1) is 8-12℃, the electrode plate spacing of the anodization is 1-2cm; the anodization is performed twice, the voltage of the first anodization is 45-55V, and the time is 2.5-4.5h; the voltage of the second anodization is 5-15V, and the time is 3-10min.

[0012] Preferably, the fluorine-containing ethylene glycol solution in step 1) comprises ammonium fluoride, ethylene glycol and water; the mass fraction of ammonium fluoride in the fluorine-containing ethylene glycol solution is 0.2-0.3%, and the mass fraction of water is 1-3%.

[0013] Preferably, the temperature of the annealing in step 2) is 400-500℃, the annealing time is 1-3h, and the annealing heating rate is 1-3℃ / min.

[0014] Preferably, the temperature of the cathodic reduction in step 3) is 8-12℃, the electrode plate spacing of the cathodic reduction is 1-2cm, the current density of the cathodic reduction is 4-6mA / cm 2 , the time of the cathodic reduction is 3-10min, and the volume fraction of formic acid in the formic acid solution is 5-10%.

[0015] Preferably, the Pd-Ag mixed solution in step 4) comprises palladium chloride, silver nitrate, polyvinylpyrrolidone, sodium citrate and water, and the molar volume ratio of palladium chloride, silver nitrate, polyvinylpyrrolidone, sodium citrate and water is 0.5-2mmol:1mmol:0.025-0.03mmol:0.75-2.1mmol:50mL.

[0016] Preferably, the concentration of the sodium borohydride solution in step 4) is 0.05-0.2mol / L, the dropping rate is 0.5-2mL / min, the molar ratio of sodium borohydride in the sodium borohydride solution to silver nitrate in the Pd-Ag mixed solution is 8-10:1; the reaction is performed under stirring, the stirring speed is 500-700rpm, and the stirring time is 0.5-2h.

[0017] The application further provides the silver palladium quantum dot anchoring defective titanium dioxide nanometer array composite photocatalyst prepared by the preparation method.

[0018] The application further provides application of the silver palladium quantum dot anchoring defective titanium dioxide nanometer array composite photocatalyst in degradation of organic pollutants and sterilization of microorganisms.

[0019] The beneficial effects of the present application are as follows:

[0020] The present application prepares a defective titanium dioxide nanometer array by a secondary anodic oxidation + cathodic reduction method, adopts a chemical reduction method to prepare a silver palladium quantum dot anchoring defective titanium dioxide nanometer array composite photocatalyst, and reasonably controls process parameters in anodic oxidation, cathodic reduction and chemical reduction processes, so that the silver palladium quantum dot anchoring defective titanium dioxide nanometer array composite photocatalyst has a dual function of degrading organic pollutants and killing microorganisms; the silver palladium quantum dot anchoring defective titanium dioxide nanometer array composite photocatalyst of the present application has a degradation efficiency of tetracycline hydrochloride 5.38 times higher than that of titanium dioxide and a degradation efficiency of ciprofloxacin 5.78 times higher than that of titanium dioxide in 100 min; the silver palladium quantum dot anchoring defective titanium dioxide nanometer array composite photocatalyst can completely inactivate escherichia coli in 200 min, and has a light killing rate of staphylococcus albus not less than 50%, which is significantly higher than that of titanium dioxide under the same killing time. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The scanning electron microscope image of the AgPd / TiO2-4.5 composite photocatalyst prepared for Example 1; 1.25 The scanning electron microscope image of the AgPd / TiO2-4.5 composite photocatalyst prepared for Example 1;

[0022] Figure 2 The scanning electron microscope image of the AgPd / TiO2-2.5 composite photocatalyst prepared for Example 2; 1.5 The scanning electron microscope image of the AgPd / TiO2-2.5 composite photocatalyst prepared for Example 2;

[0023] Figure 3 The scanning electron microscope image of the AgPd / TiO2-3.5 composite photocatalyst prepared for Example 3;

[0024] Figure 4 The light degradation rate of tetracycline hydrochloride of the AgPd / TiO2-3.5 composite photocatalyst prepared for Example 3;

[0025] Figure 5 The light degradation rate of tetracycline hydrochloride of the TiO2 catalyst;

[0026] Figure 6 The light degradation rate of ciprofloxacin of the AgPd / TiO2-3.5 composite photocatalyst prepared for Example 3;

[0027] Figure 7 The light degradation rate of ciprofloxacin of the TiO2 catalyst;

[0028] Figure 8 The light killing rate of escherichia coli of the AgPd / TiO2-3.5 composite photocatalyst prepared for Example 3;

[0029] Figure 9 The light killing rate of escherichia coli of the TiO2 catalyst;

[0030] Figure 10 The photocatalytic killing rate of AgPd / TiO2-3.5 composite photocatalyst prepared for Example 3 on Staphylococcus albus;

[0031] Figure 11 The photocatalytic killing rate of TiO2 catalyst on Staphylococcus albus. DETAILED DESCRIPTION

[0032] The application provides a preparation method of a silver-palladium quantum dot anchored defect titanium dioxide nanometer array composite photocatalyst, and comprises the following steps:

[0033] 1) Anodizing titanium sheet cathodes and titanium mesh anodes in a fluorine-containing ethylene glycol solution to obtain amorphous titanium dioxide nanometer arrays;

[0034] 2) Annealing the amorphous titanium dioxide nanometer arrays to obtain anatase titanium dioxide nanometer arrays;

[0035] 3) Taking titanium sheets as anodes and the anatase titanium dioxide nanometer arrays as cathodes, and cathodically reducing the anodes and the cathodes in a formic acid solution to obtain defect titanium dioxide nanometer arrays;

[0036] 4) Placing the defect titanium dioxide nanometer arrays in a Pd-Ag mixed solution under an argon atmosphere, and adding a sodium borohydride solution dropwise into the Pd-Ag mixed solution to react, so that a silver-palladium quantum dot anchored defect titanium dioxide nanometer array composite photocatalyst is obtained.

[0037] In the application, the titanium sheet cathodes and the titanium mesh anodes in step 1) are preferably pretreated, and the pretreatment preferably comprises sequentially performing ultrasonic cleaning and drying; the ultrasonic cleaning preferably comprises sequentially performing water ultrasonic cleaning, hydrochloric acid ultrasonic cleaning, acetone ultrasonic cleaning and anhydrous ethanol ultrasonic cleaning, the frequencies of the water ultrasonic cleaning, the hydrochloric acid ultrasonic cleaning, the acetone ultrasonic cleaning and the anhydrous ethanol ultrasonic cleaning are independently preferably 30-50 kHz, and further preferably 40 kHz; the time of the ultrasonic cleaning is independently preferably 10-20 min, and further preferably 15 min; the temperature of the drying is preferably 50-80 ℃, and further preferably 60-70 ℃; and the time of the drying is preferably 20-40 min, and further preferably 30 min.

[0038] In the present application, the temperature of the anodic oxidation in step 1) is preferably 8-12℃, further preferably 9-11℃, and more preferably 10℃; the distance between the anode plates is preferably 1-2cm, further preferably 1.5cm; the anodic oxidation is preferably carried out twice, the voltage of the first anodic oxidation is preferably 45-55V, further preferably 48-52V, and more preferably 50V; the time is preferably 2.5-4.5h, further preferably 3.3-3.8h, and more preferably 3.5h; the voltage of the second anodic oxidation is preferably 5-15V, further preferably 8-13V, and more preferably 10V; and the time is preferably 3-10min, further preferably 5-8min, and more preferably 6min.

[0039] In the present application, the fluorine-containing ethylene glycol solution in step 1) preferably comprises ammonium fluoride, ethylene glycol and water; the mass fraction of ammonium fluoride in the fluorine-containing ethylene glycol solution is preferably 0.2-0.3%, further preferably 0.22-0.28%, and more preferably 0.25%; and the mass fraction of water is preferably 1-3%, further preferably 1.5-2.5%, and more preferably 2%.

[0040] In the present application, after the anodic oxidation in step 1), the amorphous titanium dioxide nanometer array is preferably cleaned and dried, the cleaning preferably comprises deionized water cleaning and anhydrous ethanol cleaning in sequence, the number of cleaning is independently preferably 2-4 times, and further preferably 3 times; the drying temperature is preferably 50-80℃, further preferably 60-70℃; and the drying time is preferably 20-40min, and further preferably 30min.

[0041] In the present application, the annealing temperature in step 2) is preferably 400-500℃, further preferably 430-480℃, and more preferably 450℃; the annealing time is preferably 1-3h, further preferably 1.5-2.5h, and more preferably 2h; and the annealing heating rate is preferably 1-3℃ / min, further preferably 1.5-2.5℃ / min, and more preferably 2℃ / min.

[0042] In the present application, the titanium sheet in step 3) is preferably pretreated, the pretreatment preferably comprises ultrasonic cleaning and drying in sequence; the ultrasonic cleaning preferably comprises water ultrasonic cleaning, hydrochloric acid ultrasonic cleaning, acetone ultrasonic cleaning and anhydrous ethanol ultrasonic cleaning in sequence, the frequency of the water ultrasonic cleaning, the hydrochloric acid ultrasonic cleaning, the acetone ultrasonic cleaning and the anhydrous ethanol ultrasonic cleaning is independently preferably 30-50kHz, and further preferably 40kHz; the time of the ultrasonic cleaning is independently preferably 10-20min, and further preferably 15min; the drying temperature is preferably 50-80℃, further preferably 60-70℃; and the drying time is preferably 20-40min, and further preferably 30min.

[0043] In the present application, the temperature of the cathode reduction in step 3) is preferably 8-12℃, further preferably 9-11℃, and more preferably 10℃; the inter-plate distance of the cathode reduction is preferably 1-2cm, further preferably 1.5cm; the current density of the cathode reduction is preferably 4-6mA / cm 2 , further preferably 4.5-5.5mA / cm 2 , and more preferably 5mA / cm 2 ; the time of the cathode reduction is preferably 3-10min, further preferably 4-8min, and more preferably 5-6min; the volume fraction of formic acid in the formic acid solution is preferably 5-10%, further preferably 6-9%, and more preferably 7-8%.

[0044] In the present application, after the cathode reduction in step 3), the defective titanium dioxide nanometer array is preferably washed and dried, the washing preferably comprises deionized water washing and anhydrous ethanol washing in sequence, the number of washing is independently preferably 2-4 times, and further preferably 3 times; the drying temperature is preferably 50-80℃, and further preferably 60-70℃; the drying time is preferably 50-80min, and further preferably 60-70min.

[0045] In the present application, the defective titanium dioxide nanometer array in step 3) is preferably an oxygen vacancy-rich defective titanium dioxide nanometer array.

[0046] In the present application, the Pd-Ag mixed solution in step 4) is preferably aerated in argon first and then the defective titanium dioxide nanometer array is added, the flow rate of argon is preferably 3-8mL / min, and further preferably 5mL / min; the aeration is preferably carried out under stirring, the stirring speed is preferably 500-700rpm, and further preferably 600rpm; the stirring time is preferably 10-30min, and further preferably 20min.

[0047] In the present application, before the dropwise addition of the sodium borohydride solution in step 4), the Pd-Ag mixed solution is preferably stirred, the stirring speed is preferably 500-700rpm, and further preferably 600rpm; the stirring time is preferably 20-40min, and further preferably 30min.

[0048] In the present application, the Pd-Ag mixed solution in step 4) preferably comprises palladium chloride, silver nitrate, polyvinylpyrrolidone, sodium citrate and water, and the molar volume ratio of palladium chloride, silver nitrate, polyvinylpyrrolidone, sodium citrate and water is preferably 0.5-2 mmol: 1 mmol: 0.025-0.03 mmol: 0.75-2.1 mmol: 50 mL, further preferably 1-1.5 mmol: 1 mmol: 0.026-0.028 mmol: 1-1.8 mmol: 50 mL, and more preferably 1.25 mmol: 1 mmol: 0.027 mmol: 1.5 mmol: 50 mL.

[0049] In the present application, the concentration of the sodium borohydride solution in step 4) is preferably 0.05-0.2 mol / L, further preferably 0.08-0.18 mol / L, and more preferably 0.1-0.15 mol / L; the dropping rate is preferably 0.5-2 mL / min, further preferably 0.8-1.8 mL / min, and more preferably 1-1.5 mL / min; the molar ratio of sodium borohydride in the sodium borohydride solution to silver nitrate in the Pd-Ag mixed solution is preferably 8-10: 1, further preferably 8.5-9.5: 1, and more preferably 9: 1; the reaction is preferably carried out under stirring, and the stirring speed is preferably 500-700 rpm, further preferably 550-650 rpm, and more preferably 600 rpm; and the stirring time is preferably 0.5-2 h, further preferably 0.8-1.8 h, and more preferably 1-1.5 h.

[0050] In the present application, after the reaction in step 4) is completed, the silver-palladium quantum dot anchored defect titania nanometer array composite photocatalyst is preferably washed and dried, the washing preferably comprises deionized water washing and anhydrous ethanol washing performed in sequence, the number of washing is independently preferably 2-4 times, and further preferably 3 times; the drying temperature is preferably 50-80℃, further preferably 60-70℃; and the drying time is preferably 10-14 h, further preferably 12 h.

[0051] The present application also provides a silver-palladium quantum dot anchored defect titania nanometer array composite photocatalyst prepared by the preparation method.

[0052] The present application also provides application of the silver-palladium quantum dot anchored defect titania nanometer array composite photocatalyst in degradation of organic pollutants and killing of microorganisms.

[0053] The technical solutions provided by the present application are described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.

[0054] Example 1

[0055] Titanium mesh with size of 5 cm x 3 cm, aperture of 2 x 4 mm and thickness of 0.5 mm was sequentially cleaned in deionized water at a frequency of 40 kHz for 15 min, in 1 mol / L hydrochloric acid at a frequency of 40 kHz for 10 min, in acetone at a frequency of 40 kHz for 15 min, and in anhydrous ethanol at a frequency of 40 kHz for 20 min. After cleaning, the titanium mesh was placed in a 60°C oven for drying for 30 min. The above operation was repeated for a titanium sheet with size of 5 cm x 3 cm.

[0056] Titanium mesh anode and titanium sheet cathode (distance between anode and cathode was 1.5 cm) were anodized in a fluorine-containing glycol solution (mass fraction of ammonium fluoride in the fluorine-containing glycol solution was 0.25%, mass fraction of water was 2%) at a temperature of 10°C at a direct current voltage of 55 V for 4.5 h. After completion, the direct current voltage was directly adjusted to 10 V for secondary anodization for 5 min. After completion of the secondary anodization, the titanium mesh was taken out, sequentially cleaned with deionized water for 3 times and anhydrous ethanol for 3 times, and dried in a 60°C oven for 30 min after completion of the cleaning, to obtain an amorphous titanium dioxide nanometer array.

[0057] The amorphous titanium dioxide nanometer array was heated to 450°C at a rate of 2°C / min and annealed at 450°C for 2 h, to obtain an anatase titanium dioxide nanometer array.

[0058] Titanium sheet was used as anode and the anatase titanium dioxide nanometer array was used as cathode (distance between anode and cathode was 1.5 cm), and cathode reduction was performed in a formic acid aqueous solution (volume fraction of formic acid in the formic acid aqueous solution was 8%) at a temperature of 10°C at a current density of 5 mA / cm 2 for 5 min. After completion, the titanium dioxide nanometer array was taken out, sequentially cleaned with deionized water for 3 times and anhydrous ethanol for 3 times, and dried in a 60°C oven for 60 min after completion of the cleaning, to obtain a defect titanium dioxide nanometer array rich in oxygen vacancies.

[0059] Palladium chloride, silver nitrate were dissolved in deionized water, then polyvinylpyrrolidone aqueous solution (polyvinylpyrrolidone weight average molecular weight 8000) and sodium citrate aqueous solution were added to prepare a Pd-Ag mixed solution (molar volume ratio of palladium chloride, silver nitrate, polyvinylpyrrolidone, sodium citrate and water in the Pd-Ag mixed solution was 1.25 mmol: 1 mmol: 0.027 mmol: 1.5 mmol: 50 mL). The Pd-Ag mixed solution was aerated for 20 min under the argon gas at a flow rate of 5 mL / min and stirring at a speed of 600 rpm. The oxygen-enriched vacancy defect titanium dioxide nanometer array was vertically placed in the Pd-Ag mixed solution to be completely immersed, and the argon gas was passed at a flow rate of 5 mL / min and stirred at a speed of 600 rpm for 30 min. The 0.1 mol / L sodium borohydride aqueous solution was added dropwise at a speed of 1 mL / min, and the addition was stopped when the molar ratio of sodium borohydride to silver nitrate was 9:1. The reaction was carried out by passing argon gas at a flow rate of 5 mL / min and stirring at a speed of 600 rpm for 1 h. After taking out, it was sequentially washed with deionized water for 3 times and anhydrous ethanol for 3 times, and then dried in a 60°C vacuum oven for 12 h to obtain a silver palladium quantum dot anchored defect titanium dioxide nanometer array composite photocatalyst, marked as AgPd 1.25 / TiO2-4.5 composite photocatalyst.

[0060] Example 2

[0061] The titanium mesh with a size of 5 cm x 3 cm, a pore size of 2 x 4 mm and a thickness of 0.5 mm was sequentially ultrasonically cleaned in deionized water at a frequency of 40 kHz for 10 min, in 1 mol / L hydrochloric acid at a frequency of 40 kHz for 15 min, in acetone at a frequency of 40 kHz for 20 min, and in anhydrous ethanol at a frequency of 40 kHz for 15 min. After the cleaning, the titanium mesh was placed in a 50°C oven and dried for 40 min. The above operation was repeated for the titanium sheet with a size of 5 cm x 3 cm.

[0062] The titanium mesh anode and the titanium sheet cathode (the distance between the anode and the cathode was 1 cm) were anodized in a fluorine-containing ethylene glycol solution (the mass fraction of ammonium fluoride in the fluorine-containing ethylene glycol solution was 0.28%, and the mass fraction of water was 1.5%) at a direct current voltage of 45 V for 2.5 h. After the anodization, the direct current voltage was directly adjusted to 13 V for secondary anodization for 6 min. After the secondary anodization, the titanium mesh was taken out, sequentially washed with deionized water for 2 times and anhydrous ethanol for 2 times, and then placed in a 80°C oven and dried for 20 min to obtain an amorphous titanium dioxide nanometer array.

[0063] The amorphous titanium dioxide nanometer array was heated to 480°C at a rate of 1.5°C / min and annealed at 480°C for 1.5 h to obtain a anatase titanium dioxide nanometer array.

[0064] The titanium sheet was used as an anode, the anatase titanium dioxide nanometer array was used as a cathode (the distance between the anode and the cathode was 1 cm), and the reduction was performed in a formic acid aqueous solution (the volume fraction of formic acid in the formic acid aqueous solution was 6%) at a temperature of 11 ℃ at a current density of 4.5 mA / cm 2 The reduction was performed for 8 min. After the end, the titanium dioxide nanometer array was taken out, sequentially washed with deionized water for 2 times and anhydrous ethanol for 2 times, and dried in a 50 ℃ oven for 80 min after the washing was completed, to obtain the defect titanium dioxide nanometer array rich in oxygen vacancies.

[0065] Palladium chloride, silver nitrate, an aqueous solution of polyvinylpyrrolidone (the weight average molecular weight of the polyvinylpyrrolidone was 8000) and an aqueous solution of sodium citrate were dissolved in deionized water to prepare a Pd-Ag mixed solution (the molar volume ratio of palladium chloride, silver nitrate, polyvinylpyrrolidone, sodium citrate and water in the Pd-Ag mixed solution was 1.5 mmol: 1 mmol: 0.026 mmol: 1.8 mmol: 50 mL). The Pd-Ag mixed solution was aerated for 10 min under the stirring of argon at a flow rate of 3 mL / min and a rotation speed of 700 rpm. The defect titanium dioxide nanometer array rich in oxygen vacancies was vertically placed in the Pd-Ag mixed solution to be completely immersed, argon was introduced at a flow rate of 3 mL / min, and the stirring was performed at a rotation speed of 500 rpm for 40 min. A 0.18 mol / L aqueous solution of sodium borohydride was added dropwise at a speed of 1.8 mL / min, and the addition was ended when the molar ratio of sodium borohydride to silver nitrate was 8.5:1. Argon was introduced at a flow rate of 3 mL / min, and the stirring was performed at a rotation speed of 550 rpm for 1.8 h to perform the reaction. After being taken out, the defect titanium dioxide nanometer array rich in oxygen vacancies was sequentially washed with deionized water for 2 times and anhydrous ethanol for 2 times, and was dried in a 80 ℃ vacuum oven for 10 h to obtain a silver palladium quantum dot anchored defect titanium dioxide nanometer array composite photocatalyst, which was marked as AgPd 1.5 / TiO2-2.5 composite photocatalyst.

[0066] Example 3

[0067] A titanium mesh with a size of 5 cm x 3 cm, a pore size of 2 x 4 mm and a thickness of 0.5 mm was sequentially ultrasonically cleaned in deionized water at a frequency of 40 kHz for 10 min, in 1 mol / L hydrochloric acid at a frequency of 40 kHz for 15 min, in acetone at a frequency of 40 kHz for 10 min, and in anhydrous ethanol at a frequency of 40 kHz for 20 min. After the cleaning was completed, the titanium mesh was placed in a 80 ℃ oven for drying for 20 min. A 5 cm x 3 cm titanium sheet was subjected to the above operation.

[0068] An anode of titanium mesh and a cathode of titanium sheet (the distance between the anode and the cathode is 2 cm) were anodized in a fluoroethylene glycol solution (the mass fraction of ammonium fluoride in the fluoroethylene glycol solution is 0.22%, and the mass fraction of water is 2.5%) at a temperature of 9℃ for 3.5 h under a direct current voltage of 50 V. After the anodization, the direct current voltage was directly adjusted to 8 V for secondary anodization for 8 min. After the secondary anodization, the titanium mesh was taken out, sequentially washed with deionized water for 4 times and anhydrous ethanol for 4 times, and then dried in an oven at 50℃ for 40 min to obtain an amorphous titanium dioxide nanometer array.

[0069] The amorphous titanium dioxide nanometer array was heated to 430℃ at a rate of 2.5℃ / min, and then annealed at 430℃ for 2.5 h to obtain an anatase titanium dioxide nanometer array.

[0070] An anode of titanium sheet and a cathode of the anatase titanium dioxide nanometer array (the distance between the anode and the cathode is 2 cm) were cathodically reduced in a formic acid aqueous solution (the volume fraction of formic acid in the formic acid aqueous solution is 9%) at a temperature of 9℃ for 4 min under a direct current voltage of 5.5 mA / cm 2 After the cathodic reduction, the titanium dioxide nanometer array was taken out, sequentially washed with deionized water for 4 times and anhydrous ethanol for 4 times, and then dried in an oven at 80℃ for 50 min to obtain a defect titanium dioxide nanometer array rich in oxygen vacancies.

[0071] Palladium chloride and silver nitrate were dissolved in deionized water, and then polyvinylpyrrolidone (the weight average molecular weight of the polyvinylpyrrolidone is 8000) and sodium citrate aqueous solution were added to prepare a Pd-Ag mixed solution (the molar volume ratio of palladium chloride, silver nitrate, polyvinylpyrrolidone, sodium citrate, and water in the Pd-Ag mixed solution is 1 mmol: 1 mmol: 0.028 mmol: 1 mmol: 50 mL). The Pd-Ag mixed solution was aerated for 30 min under an argon gas flow of 8 mL / min and a stirring speed of 500 rpm. The defect titanium dioxide nanometer array rich in oxygen vacancies was vertically placed in the Pd-Ag mixed solution to be completely immersed, and then argon gas was introduced at a flow rate of 8 mL / min and the solution was stirred at a speed of 700 rpm for 20 min. Sodium borohydride aqueous solution (0.08 mol / L) was added dropwise at a rate of 0.8 mL / min, and the addition was stopped when the molar ratio of sodium borohydride to silver nitrate was 9.5:1. Argon gas was introduced at a flow rate of 8 mL / min and the solution was stirred at a speed of 650 rpm for 0.8 h for reaction. After the reaction, the solution was sequentially washed with deionized water for 4 times and anhydrous ethanol for 4 times, and then dried in a vacuum oven at 50℃ for 14 h to obtain a silver palladium quantum dot anchored defect titanium dioxide nanometer array composite photocatalyst, which is marked as AgPd / TiO2-3.5 composite photocatalyst.

[0072] The AgPd / TiO2-3.5 composite photocatalyst and TiO2 catalyst prepared in Example 3 (2.5 × 1.5 cm) were added to 30 mL of a 20 ppm tetracycline hydrochloride aqueous solution to obtain a mixed solution. The temperature of the mixed solution was controlled at 25°C, and the solution was stirred at 100 rpm for 30 min in the dark to obtain the test solution. The test solution was kept at 25°C and placed under a 300W xenon lamp (wavelength > 420 nm) with a filter, and stirred continuously at 100 rpm. Every 20 min, 3 mL of the test solution was transferred to a centrifuge and centrifuged at 1000 rpm for 5 min. The supernatant was collected, and the absorbance at 356 nm was measured using a UV-Vis spectrophotometer. The concentration of tetracycline hydrochloride in the test solution was calculated, and the photodegradation rates of tetracycline hydrochloride by the AgPd / TiO2-3.5 composite photocatalyst and TiO2 catalyst were obtained, respectively. Figure 4 , 5 As shown.

[0073] Depend on Figure 4 , 5 It can be seen that after 100 min of degradation, the AgPd / TiO2-3.5 composite photocatalyst achieved a photodegradation rate of 93.22% for tetracycline hydrochloride, which is 5.38 times higher than that of TiO2 catalyst under the same degradation time.

[0074] The AgPd / TiO2-3.5 composite photocatalyst and TiO2 catalyst prepared in Example 3 (2.5 × 1.5 cm) were added to 30 mL of a 12 ppm ciprofloxacin aqueous solution to obtain a mixed solution. The temperature of the mixed solution was controlled at 25°C, and the solution was stirred at 100 rpm for 30 min in the dark to obtain the test solution. The test solution was kept at 25°C and placed under a 300W xenon lamp (wavelength > 420 nm) with a filter, and stirred continuously at 100 rpm. Every 20 min, 3 mL of the test solution was transferred to a centrifuge and centrifuged at 1000 rpm for 100 min. The supernatant was collected, and the absorbance at 278 nm was measured using a UV-Vis spectrophotometer. The concentration of ciprofloxacin in the test solution was calculated, and the photodegradation rates of ciprofloxacin by the AgPd / TiO2-3.5 composite photocatalyst and TiO2 catalyst were obtained, respectively. Figure 6 , 7 As shown.

[0075] Depend on Figure 6 , 7 It can be seen that after 100 min of degradation, the AgPd / TiO2-3.5 composite photocatalyst achieved a photodegradation rate of 84.11% for ciprofloxacin, which is 5.78 times higher than that of TiO2 catalyst under the same degradation time.

[0076] The AgPd / TiO2-3.5 composite photocatalyst and TiO2 catalyst prepared in Example 3 (2.5 × 1.5 cm) were added to 30 mL of water, respectively, to achieve a colony density of 7.3 log. 10 A mixed bacterial suspension was obtained by mixing the *E. coli* solution (cfu / mL) at 25°C and stirring at 100 rpm for 30 min in the dark. The test suspension was then placed under a 300W xenon lamp (wavelength >420 nm) with a filter at 25°C and stirred continuously at 100 rpm. Every 40 min, 10 μL of the test suspension was transferred, diluted 100 times with distilled water, and spread onto nutrient agar medium (composed of 10.0 g / L peptone, 3.0 g / L beef meal, 5.0 g / L sodium chloride, and 15.0 g / L agar). The medium was then transferred to a shaker at 36°C and incubated at 180 rpm for 24 h. The survival of *E. coli* was observed. Figure 8 , 9 As shown.

[0077] Depend on Figure 8 , 9 It can be seen that after 200 min of disinfection, the AgPd / TiO2-3.5 composite photocatalyst can completely inactivate Escherichia coli, and its photo-disinfection rate of Escherichia coli is significantly better than that of TiO2 catalyst under the same disinfection time.

[0078] The AgPd / TiO2-3.5 composite photocatalyst and TiO2 catalyst prepared in Example 3 (2.5 × 1.5 cm) were added to 30 mL of water, respectively, to achieve a colony density of 7.5 log₂. 10 A mixed bacterial suspension was obtained by adding (cfu / mL) Staphylococcus aureus solution to a solution of Staphylococcus aureus. The temperature of the mixed bacterial suspension was controlled at 25℃, and the suspension was stirred at 100 rpm for 30 min in the dark to obtain the test bacterial suspension. The test bacterial suspension was controlled at 25℃ and placed under a 300W xenon lamp (wavelength >420nm) with a filter. The suspension was stirred continuously at 100 rpm. Every 40 min, 10 μL of the test bacterial suspension was transferred out, diluted 100 times with distilled water, and spread onto nutrient agar medium (nutrient agar medium composition: peptone 10.0 g / L, beef meal 3.0 g / L, sodium chloride 5.0 g / L, agar 15.0 g / L). Then, it was transferred to a shaker at 36℃ and incubated at 180 rpm for 24 h. The survival of Staphylococcus aureus was observed. Figure 10 , 11 As shown.

[0079] Depend on Figure 10 , 11It can be seen that the photocatalytic inactivation rate of AgPd / TiO2-3.5 composite photocatalyst on white staphylococcus is not less than 50% after 200 min, which is significantly better than that of TiO2 catalyst under the same inactivation time.

[0080] The above merely describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a silver-palladium quantum dot-anchored defect titanium dioxide nanoarray composite photocatalyst, characterized in that, It includes the following steps: 1) Anodize the titanium sheet cathode and titanium mesh anode in a fluorinated ethylene glycol solution to obtain an amorphous titanium dioxide nanoarray; 2) Annealing the amorphous titanium dioxide nanoarray yields anatase titanium dioxide nanoarray; 3) Using a titanium sheet as the anode and anatase titanium dioxide nanoarray as the cathode, the anode and cathode are subjected to cathode reduction in formic acid solution to obtain a defective titanium dioxide nanoarray. 4) Under an argon atmosphere, a defective titanium dioxide nanoarray was placed in a Pd atmosphere. In the Ag mixed solution, to Pd A sodium borohydride solution was added dropwise to a mixed Ag solution to carry out the reaction, thus obtaining a silver-palladium quantum dot-anchored defect titanium dioxide nanoarray composite photocatalyst. The anodizing is performed in two stages. The first anodizing is performed at a voltage of 45–55V for 2.5–4.5 hours; the second anodizing is performed at a voltage of 5–15V for 3–10 minutes. Step 4) Pd The Ag mixed solution contains palladium chloride, silver nitrate, polyvinylpyrrolidone, sodium citrate, and water, with a molar volume ratio of 0.5–2 mmol: 1 mmol: 0.025–0.03 mmol: 0.75–2.1 mmol: 50 mL.

2. The preparation method according to claim 1, characterized in that, Step 1) The anodizing temperature is 8-12℃, and the spacing between the anodized plates is 1-2cm.

3. The preparation method according to claim 1 or 2, characterized in that, Step 1) The fluorinated ethylene glycol solution contains ammonium fluoride, ethylene glycol and water; the mass fraction of ammonium fluoride in the fluorinated ethylene glycol solution is 0.2-0.3%, and the mass fraction of water is 1-3%.

4. The preparation method according to claim 3, characterized in that, Step 2) The annealing temperature is 400-500℃, the annealing time is 1-3h, and the annealing heating rate is 1-3℃ / min.

5. The preparation method according to claim 4, characterized in that, Step 3) The cathode reduction temperature is 8–12°C, the cathode reduction electrode spacing is 1–2 cm, and the cathode reduction current density is 4–6 mA / cm². 2 The cathode reduction time is 3 to 10 minutes, and the volume fraction of formic acid in the formic acid solution is 5 to 10%.

6. The preparation method according to claim 5, characterized in that, Step 4) The concentration of the sodium borohydride solution is 0.05–0.2 mol / L, and the dropping rate is 0.5–2 mL / min. The sodium borohydride solution contains sodium borohydride and Pd. The molar ratio of silver nitrate in the Ag mixed solution is 8–10:1; the reaction is carried out under stirring conditions, with a stirring speed of 500–700 rpm and a stirring time of 0.5–2 h.

7. The silver-palladium quantum dot anchored defect titanium dioxide nanoarray composite photocatalyst prepared by the preparation method according to any one of claims 1 to 6.

8. The application of the silver-palladium quantum dot-anchored defect titanium dioxide nanoarray composite photocatalyst according to claim 7 in the degradation of organic pollutants and the elimination of microorganisms.

Images