Sulfur-doped zinc oxide nano material with broad-spectrum piezoelectric photocatalytic degradation characteristic as well as preparation method and application of sulfur-doped zinc oxide nano material

Abstract

The invention discloses a sulfur-doped zinc oxide nano material with broad-spectrum piezoelectric photocatalytic degradation characteristics as well as a preparation method and application of the sulfur-doped zinc oxide nano material. The method comprises the following steps: slowly dropwise adding an ethanol mixed solution of an alkali source and a sulfur source into an ethanol solution of a zinc source, stirring for 0.5-1h at normal temperature, then transferring into a high-pressure reaction kettle, carrying out hydrothermal reaction for 18-26h at 120-160 DEG C, cooling, washing and drying to obtain the product. According to the method, by means of ion doping and morphology regulation and control, a zinc oxide absorption light area is expanded to a visible light area, the morphology can be regulated and controlled from a nano-particle shape to a nano-rod shape, and the length of the nano-rod is 50-100 nm; the obtained nano material has excellent piezoelectric electro-catalytic performance in a visible region, the degradation rate of the nano material to acid orange 7 within 100 min under the action of visible light and ultrasound reaches 60% or above, and the nano material has broad-spectrum degradation characteristic to various pollutants and has application value in the fields of environment cleaning, energy conversion and the like.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric photocatalytic materials technology, specifically to a sulfur-doped zinc oxide nanomaterial with broad-spectrum piezoelectric photocatalytic degradation characteristics, its preparation method, and its applications. Background Technology

[0002] With the continuous development of global industrialization, water pollution in the environment has become increasingly serious. Water pollution contains large amounts of pollutants such as organic dyes and antibiotics, which pose a serious threat to both humans and nature. In recent years, the concept of piezoelectric photocatalysis has been proposed and continuously developed. Piezoelectric photocatalysis technology retains the advantage of photocatalysis in utilizing solar energy to degrade pollutants, while also utilizing the characteristic of piezoelectric materials to generate a built-in electric field under stress, thereby further enhancing the separation of photogenerated carriers. The two work synergistically to greatly improve the efficiency of pollutant degradation, while simultaneously achieving green, environmentally friendly, and sustainable results.

[0003] ZnO, a common semiconductor photocatalytic material, possesses excellent optical properties, stable chemical properties, and is green and non-toxic. It is also a piezoelectric material, making it widely used in piezoelectric photocatalysis. However, ZnO has a relatively wide band gap (approximately 3.37 eV), limiting its absorption to the ultraviolet region of sunlight. Furthermore, significant carrier recombination and relatively low piezoelectric performance restrict its catalytic degradation efficiency. To address these issues, researchers have employed doping and semiconductor composite techniques to enhance the piezoelectric photocatalytic performance of nano-ZnO.

[0004] Chinese invention patent CN110841668A discloses a method for preparing a one-dimensional zinc oxide nanorod array and a two-dimensional bismuth oxyiodide nanocomposite material, and its application in the effective removal of pollutants from water using piezoelectric-photocatalysis. By compositing zinc oxide nanorods with bismuth oxyiodide sheets on ITO glass, the photoresponse range of the material is extended to visible light, while more active sites are introduced, thereby improving the piezoelectric-photocatalytic degradation performance of ZnO. However, this technology requires growing the material on ITO glass, which is a relatively cumbersome process, and the zinc oxide nanorod array grown on ITO glass is prone to detachment, which limits its application.

[0005] Chinese invention patent CN118698533A discloses a method for preparing and applying metal-doped ZnO-based piezoelectric-photocatalytic materials. This method uses a simple hydrothermal method to dope ZnO with metal elements, extending the photoresponse range of ZnO to the visible light spectrum. Simultaneously, doping induces lattice distortion, thereby exacerbating the asymmetry at the ZnO center and enhancing its piezoelectric properties, ultimately improving the overall piezoelectric-photocatalytic performance of ZnO. However, this technique, when doping with metal elements, easily introduces other metal oxide impurities under the alkaline conditions of ZnO synthesis. Furthermore, the hydrothermal temperature for doping certain metal elements can reach up to 500℃, resulting in high energy consumption.

[0006] Chinese invention patent CN117342605B discloses a method for preparing a sulfur-doped porous zinc oxide catalyst and its application. The method involves synthesizing porous zinc oxide precipitate via a solution method, followed by calcination in a muffle furnace. The zinc oxide is then mixed with sulfur using a plasma high-energy ball mill, resulting in a sample with excellent carbon dioxide reduction capabilities. However, this method is cumbersome, requiring the synthesis of zinc oxide followed by calcination, and finally ball milling to obtain the sulfur-doped zinc oxide. This results in high cost and energy consumption, hindering industrial mass production.

[0007] Chinese invention patent CN108298575B discloses a method for synthesizing high-valence sulfur-doped zinc oxide optoelectronic materials. This method involves dispersing solid zinc oxide into a sulfur source solution while stirring for ion exchange, followed by alkali treatment and calcination to obtain the high-valence sulfur-doped zinc oxide optoelectronic material, which exhibits photocatalytic properties under visible light. However, this technique is cumbersome, requiring the synthesis of solid zinc oxide before sulfur doping, making a one-step synthesis of sulfur-doped zinc oxide impossible. Furthermore, the synthesized product still requires calcination, and the resulting sulfur-doped zinc oxide exhibits poor degradation performance. Summary of the Invention

[0008] The purpose of this invention is to provide a sulfur-doped zinc oxide nanomaterial with broad-spectrum piezoelectric photocatalytic degradation characteristics and its preparation method. This technology is simple to operate and can extend the absorption range of ZnO to visible light, thereby enhancing its photocatalytic performance. At the same time, the introduction of sulfur source will cause lattice distortion of zinc oxide and exacerbate its central asymmetry, thereby improving its piezoelectric performance to a certain extent. Finally, it comprehensively improves its piezoelectric photocatalytic performance.

[0009] Another objective of this invention is to provide sulfur-doped zinc oxide nanomaterials with tunable morphology and broad-spectrum piezoelectric photocatalytic degradation properties. The morphology of this material is tunable, ranging from nanoparticles to nanorods. Under piezoelectric and light irradiation, it can degrade various organic dyes and antibiotics, thereby improving the degradation efficiency and overall degradation capacity of zinc oxide and achieving broad-spectrum degradation.

[0010] The objective of this invention is achieved through the following technical solution:

[0011] Sulfur-doped zinc oxide nanomaterials with broad-spectrum piezoelectric photocatalytic degradation characteristics: A mixed ethanol solution of an alkali source and a sulfur source is added to an ethanol solution of a zinc source, stirred at room temperature for 0.5-1 h, transferred to a high-pressure reactor, and hydrothermally reacted at 120-160℃ for 18-26 h. After cooling, washing, and drying, the nanomaterials are obtained. The molar ratio of the alkali source to the zinc source is (10-30):1. The sulfur source is one or more of thiourea, thioacetamide, and sodium sulfide.

[0012] To further achieve the objectives of this invention, preferably, the alkali source is one or more of sodium hydroxide, potassium hydroxide, and ammonia water.

[0013] Preferably, the zinc source is one or more of zinc acetate, zinc nitrate, zinc chloride, and zinc sulfate.

[0014] Preferably, the molar ratio of sulfur source to zinc source is (0.06-0.1):1.

[0015] Preferably, the cooling is achieved by natural cooling to 20-30°C at room temperature.

[0016] Preferably, the washing process involves cooling the reactants, thoroughly mixing the cooled product with a mixture of water and ethanol, centrifuging the mixture, collecting the centrifuged product, adding a mixture of deionized water and ethanol, and centrifuging again. This process is repeated 2-4 times in total.

[0017] Preferably, the mass ratio of the cooling product to the mixture is 1:(10-15); the volume ratio of water to ethanol is 1:1-2; the centrifugation speed is 4000-6000 r / mins; and the centrifugation time is 5-10 mins.

[0018] Preferably, the drying is carried out in a drying oven at 60-70°C for 8-12 hours.

[0019] The preparation method of the sulfur-doped zinc oxide nanomaterial with broad-spectrum piezoelectric photocatalytic degradation characteristics includes the following steps:

[0020] 1) Using ethanol as a solvent, add a mixed solution of alkali source and sulfur source to an ethanol solution of zinc source;

[0021] 2) Stir the product obtained in step 1) uniformly at room temperature for 0.5-1h, and then transfer it to a high-pressure reactor for hydrothermal reaction at 120-160℃ for 18-26h;

[0022] 3) Cool, wash and dry the product obtained in step 2) to obtain sulfur-doped zinc oxide nanomaterials with broad-spectrum piezoelectric photocatalytic degradation characteristics.

[0023] The application of the sulfur-doped zinc oxide nanomaterial with broad-spectrum piezoelectric photocatalytic degradation characteristics in the degradation of organic dyes and antibiotics: the organic dyes are Acid Orange 7 and Methyl Orange, and the antibiotics are tetracycline and ciprofloxacin.

[0024] Compared with the prior art, the present invention has the following characteristics:

[0025] 1) This invention extends the light absorption range of zinc oxide into the visible light region by doping with sulfur, thus achieving the purpose of degrading organic dyes and organic matter under visible light.

[0026] 2) This invention distorts the lattice of zinc oxide by doping with sulfur, exacerbating its central asymmetry and improving its piezoelectric properties to a certain extent, thereby comprehensively improving the piezoelectric photocatalytic performance.

[0027] 3) This invention controls the morphology of zinc oxide by adjusting the ratio of alkali source and zinc source, and synthesizes nanorod-shaped zinc oxide with excellent piezoelectric properties. Compared with commercial zinc oxide in the prior art, sulfur-doped zinc oxide material has excellent broad-spectrum piezoelectric photocatalytic degradation performance.

[0028] 4) The sulfur-doped zinc oxide nanomaterial synthesized by this invention has a simple preparation process and low cost. It can be prepared in large quantities by simply mixing an appropriate ratio of alkali source, sulfur source and zinc source and then synthesizing it through hydrothermal synthesis without the need for complex equipment and extreme reaction conditions. Attached Figure Description

[0029] Figure 1 The X-ray diffraction patterns are those of the samples obtained in Comparative Examples 1, 2, 3, 4, and 5, and Examples 1, 2, and 3.

[0030] Figure 2 a, b, and c are transmission electron micrographs of the samples obtained in Comparative Example 1, Comparative Example 2, and Example 1, respectively.

[0031] Figure 3 The UV-Vis absorbance spectra of the samples obtained in Comparative Example 1 and Example 1 are shown.

[0032] Figure 4 The electrochemical impedance spectroscopy of the samples obtained in Comparative Example 1 and Example 1 is shown.

[0033] Figure 5 The degradation curves of 15 mg / L Acid Orange 7 under light and ultrasound are shown for Comparative Examples 1, 2, 3, 4, 5, 6, Example 1, Example 2, and Example 3.

[0034] Figure 6 The graph shows the degradation kinetic constants of 15 mg / L Acid Orange 7 under light and ultrasound in Comparative Examples 1, 2, 3, 4, 5, 6, Example 1, Example 2, and Example 3.

[0035] Figure 7 The degradation curves of 15 mg / L Acid Orange 7 under light and ultrasound (L+U) and light alone (L) are shown for Examples 1, 2, and 3.

[0036] Figure 8 The graph shows the degradation kinetic constants of 15 mg / L Acid Orange 7 under light and ultrasound (L+U) and light alone (L) in Examples 1, 2, and 3.

[0037] Figure 9 The degradation curves of methyl orange, ciprofloxacin and tetracycline at 15 mg / L are shown for Comparative Example 1, Comparative Example 6 and Example 1 under light and ultrasound.

[0038] Figure 10 The graph shows the degradation kinetic constants of 15 mg / L methyl orange, ciprofloxacin and tetracycline in Comparative Examples 1, 6 and 1 under light and ultrasound. Detailed Implementation

[0039] The present invention will be further described below with reference to embodiments and accompanying drawings to illustrate and explain the present invention, but the embodiments of the present invention are not limited thereto.

[0040] Due to its wide band gap (approximately 3.37 eV), nano zinc oxide exhibits photoresponse only in the ultraviolet region and no response in the visible region. Furthermore, its low piezoelectric properties result in low piezoelectric photocatalytic degradation efficiency in the visible region, and it only degrades a limited number of pollutants, thus limiting the scope of pollutant degradation.

[0041] Most existing technologies for zinc oxide piezoelectric photocatalysis involve metal doping, which easily leads to the formation of byproducts and affects the purity of the main product. Existing technologies for sulfur-doped zinc oxide nanomaterials mostly require expensive reagents, such as zinc acetylacetonate (an organometallic reagent with high production costs), and cannot achieve one-step synthesis. Furthermore, the zinc sources used, such as zinc acetylacetonate, solvents like ethylenediamine and polyethylene glycol, and surfactants like CTAB, are difficult to remove through washing and require high-temperature calcination for decomposition and removal. Therefore, the products obtained by existing technologies still require calcination treatment. If zinc oxide is synthesized first and then doped without calcination, the resulting material has many defects and poor crystallinity.

[0042] In particular, most sulfur-doped zinc oxide synthesized by existing technologies is in the form of nanoparticles. However, the high random orientation of particulate piezoelectric materials leads to disordered internal polarization, resulting in low piezoelectric output. Existing technologies first synthesize zinc oxide and then perform sulfur doping, which limits sulfur doping to the surface of zinc oxide and makes it difficult for sulfur to penetrate into the zinc oxide lattice.

[0043] This invention introduces impurity energy levels through non-metallic ion doping, extending the absorption band gap of zinc oxide, which originally had no absorption in the visible light range, into the visible light region, thus enabling visible light photocatalysis. Furthermore, non-metallic ion doping, compared to metallic ion doping, does not generate other oxide impurities during synthesis, ensuring product purity. The sulfur atoms introduced in this invention replace some oxygen atoms in the ZnO lattice through substitutional doping. Since the radius of a sulfur atom (1.05 Å) is larger than that of an oxygen atom (0.66 Å), the doped ZnO lattice is distorted, exacerbating its central asymmetry. This results in greater deformation of the material under stress, generating a stronger built-in electric field, thereby improving its piezoelectric properties.

[0044] Furthermore, this invention achieves controllable material morphology by adjusting the molar ratio of the alkali source to the zinc source. The synthesized sulfur-doped zinc oxide can be controlled from 10-20 nm nanoparticles to 50-100 nm long nanorods. Because the rod-shaped morphology is easily deformed under stress and has a defined polarization axis, it generates a built-in electric field, providing a directional high-speed channel for charge carriers, reducing carrier recombination, and enabling a high piezoelectric response. Sulfur doping can broaden light absorption but also induce lattice distortion, exacerbating central asymmetry.

[0045] This invention employs a one-step hydrothermal method, simultaneously hydrothermally synthesizing and doping zinc oxide. The resulting material exhibits good crystallinity and requires no calcination. The sulfur-doped zinc oxide of this invention enters the crystal lattice, causing lattice distortion. This lattice distortion exacerbates central asymmetry, thereby enhancing piezoelectric properties.

[0046] This invention uses ethanol as a solvent, which is less polar than water, thus slowing down the reaction kinetics and promoting the formation of nanomaterials with uniform size and good crystallinity. Ethanol can also act as a structure-directing agent, promoting crystal growth along the c-axis and facilitating the growth into nanorod structures. Ethanol is also a common industrial reagent, inexpensive, and can be produced on a large scale. In contrast, if water is used as a solvent, agglomeration is likely to occur, resulting in particles with uncontrollable morphology.

[0047] The reagents used in this invention decompose into soluble salts after high-temperature hydrothermal treatment, leaving no difficult-to-remove organic products. Therefore, they can be removed by washing without calcination. Furthermore, the sulfur-doped zinc oxide synthesized in this one-step hydrothermal process has high crystallinity and also requires no calcination. This invention discovers that by controlling the ratio of hydroxide ions to zinc atoms, when the ratio is below 10, the synthesized product is in the form of nanoparticles. When the ratio reaches 10, the high concentration of hydroxide ions and ethanol acts as a structure-directing agent, causing the crystals to preferentially grow along the c-axis, thus synthesizing nanorod-shaped zinc oxide with high-voltage electro-photocatalytic properties.

[0048] Through the above-mentioned means and simple process methods, the present invention synthesizes sulfur-doped zinc oxide nanomaterials with excellent piezoelectric photocatalytic effect and broad-spectrum degradation characteristics, exhibiting degradation performance on a variety of dyes and antibiotics.

[0049] Therefore, the present invention proposes a technical solution for sulfur-doped zinc oxide nanomaterials with broad-spectrum piezoelectric photocatalytic degradation characteristics. The solution involves adding an ethanol mixture of an alkali source and a sulfur source to an ethanol solution of a zinc source, stirring at room temperature for 0.5-1 h, transferring the mixture to a high-pressure reactor, and hydrothermally reacting it at 120-160℃ for 18-26 h. The resulting material is then cooled, washed, and dried. The molar ratio of the alkali source to the zinc source is controlled to be (10-30):1. The sulfur source is selected from one or more of thiourea, thioacetamide, and sodium sulfide.

[0050] The alkaline source is of particular significance, and one or more commonly used in the field are sodium hydroxide, potassium hydroxide, and ammonia. The zinc source is one or more commonly used zinc acetate, zinc nitrate, zinc chloride, and zinc sulfate; preferably, the molar ratio of sulfur source to zinc source is controlled at (0.06-0.1):1.

[0051] The embodiments and comparative examples in this invention were prepared and tested using the same method. The test method for the piezoelectric photocatalytic performance of the samples is as follows:

[0052] Weigh 0.05 g of samples from each example and comparative example, place them in a jacketed beaker, and add 50 ml of 15 mg / L Acid Orange 7 solution. Stir magnetically for 30 min in the dark to reach adsorption equilibrium. Subsequently, use a 300 W xenon lamp (with a 400 nm filter) as the visible light source and a 180 W ultrasonic machine as the mechanical force source, with cooling water flowing through to maintain the temperature stability of the system. Simultaneously irradiate and sonicate the Acid Orange 7 solution. Take an appropriate amount of solution from the beaker every 20 mins, and use an Agilent Cary 60 UV-Vis spectrophotometer to measure the absorbance of the Acid Orange 7 solution under different irradiation and ultrasonic times (characteristic peak at 485 nm). The piezoelectric photocatalytic performance of the prepared material is evaluated based on the measured absorbance of the Acid Orange 7 solution (photocatalysis alone means no ultrasonic machine is introduced, only a xenon lamp is used as the visible light source).

[0053] To better compare the piezoelectric photocatalytic efficiency of different catalysts, a kinetic analysis was performed on the degradation of Acid Orange 7 solution in water. The degradation kinetic coefficients were obtained by fitting ln(C0 / C) to the ordinate and time t (min) to the abscissa. The degradation reaction conforms to the Langmuir-HinShelwood apparent first-order kinetic model. The simplified apparent first-order kinetic model is as follows:

[0054] ln(C0 / C)=kapp t

[0055] C0 is the initial concentration of the reactant (mg / L), C is the concentration of the reactant at time t (mg / L), and k app is the apparent first-order rate constant, and t is the reaction time.

[0056] To illustrate the excellent piezoelectric photocatalytic performance of the prepared sulfur-doped zinc oxide nanomaterials, the above methods were used to compare and illustrate the degradation of a 15 mg / L Acid Orange 7 solution under light + ultrasound (L+U) and light alone (L) conditions.

[0057] To demonstrate that the prepared sulfur-doped zinc oxide nanomaterials have broad-spectrum degradation performance, pure zinc oxide (Comparative Example 1), commercial zinc oxide (Comparative Example 6), and the prepared sample (Example 1) were compared and analyzed by degrading methyl orange, tetracycline, and ciprofloxacin at a concentration of 15 mg / L under light and ultrasound conditions.

[0058] Comparative Example 1

[0059] A method for preparing nano-zinc oxide materials that absorb only in the ultraviolet region, comprising the following steps:

[0060] 1) Weigh 0.2 g of sodium hydroxide and dissolve it in 30 ml of ethanol. Stir until dissolved. Then weigh 1.098 g of zinc acetate dihydrate and add it to 20 ml of ethanol and stir. The molar ratio of hydroxide ions to zinc atoms is 1.

[0061] 2) Slowly add the dissolved sodium hydroxide ethanol solution dropwise to the zinc acetate dihydrate ethanol solution. After the addition is complete, stir at room temperature for 30 minutes to obtain a mixed solution.

[0062] 3) Transfer the above mixed solution to a 100 ml high-pressure reactor and hydrothermally incubate at 150 °C for 24 h. After the reaction is complete, allow the reactor to cool to room temperature (25 °C), collect the product, and then add 30 ml of a 1:1 mixture of deionized water and ethanol. Centrifuge at 5000 r / min for 5 min. Repeat the process of mixing the product with the above mixed solution and centrifuging three more times. Then dry in a vacuum drying oven at 60 °C for 8 h to obtain nano-zinc oxide that absorbs only in the ultraviolet region.

[0063] Comparative Example 2

[0064] A method for preparing sulfur-doped zinc oxide nanomaterials includes the following steps:

[0065] 1) Weigh 0.2 g of sodium hydroxide and 0.0075 g of thiourea and dissolve them in 30 ml of ethanol. Stir until dissolved. Then weigh 1.098 g of zinc acetate dihydrate and add it to 20 ml of ethanol and stir. The molar ratio of hydroxide ions to zinc atoms is 1, and the molar ratio of sulfur atoms to zinc atoms is 0.02.

[0066] 2) Slowly add the dissolved sodium hydroxide and thiourea mixture to the zinc acetate dihydrate ethanol solution. After the addition is complete, stir at room temperature for 40 minutes to obtain the mixed solution.

[0067] 3) Transfer the above mixed solution to a 100 ml high-pressure reactor and hydrothermally incubate at 120 °C for 18 h. After the reaction, allow the reactor to cool to room temperature (25 °C), collect the product, and then add 40 ml of a mixture of deionized water and ethanol (volume ratio 1:1). Centrifuge at 5000 r / min for 6 min; repeat the process of mixing the centrifuged product with the same solution and centrifuging three more times. Then dry in a vacuum drying oven at 60 °C for 9 h to obtain sulfur-doped zinc oxide nanoparticles with piezoelectric photocatalytic degradation properties.

[0068] Comparative Example 3

[0069] A method for preparing sulfur-doped zinc oxide nanomaterials includes the following steps:

[0070] 1) Weigh 0.2 g of sodium hydroxide and 0.045 g of thiourea and dissolve them in 30 ml of ethanol. Stir until dissolved. Then weigh 1.098 g of zinc acetate dihydrate and add it to 20 ml of ethanol and stir. The molar ratio of hydroxide to zinc atoms is 1, and the molar ratio of sulfur atoms to zinc atoms is 0.12.

[0071] 2) Slowly add the dissolved sodium hydroxide and thiourea mixture to the zinc acetate dihydrate ethanol solution, and stir at room temperature for 30 min after the addition is complete.

[0072] 3) Transfer the above mixed solution to a 100 ml high-pressure reactor and hydrothermally incubate at 130 °C for 20 h. After the reaction, allow the reactor to cool to room temperature (25 °C), collect the product, and then add 40 ml of a mixed solution of deionized water and ethanol (volume ratio 1:1). Centrifuge at 5000 r / min for 8 min; repeat the process of mixing the centrifuged product with the same solution and centrifuging 5 times. Then dry in a vacuum drying oven at 65 °C for 10 h to obtain sulfur-doped zinc oxide nanoparticles with piezoelectric photocatalytic degradation properties.

[0073] Comparative Example 4

[0074] A method for preparing sulfur-doped zinc oxide nanoparticles includes the following steps:

[0075] 1) Weigh 1.6g of sodium hydroxide and 0.0225g of thiourea and dissolve them in 30ml of ethanol. Stir until dissolved. Then weigh 1.098g of zinc acetate dihydrate and add it to 20ml of ethanol and stir. The molar ratio of hydroxide to zinc atoms is 8, and the molar ratio of sulfur atoms to zinc atoms is 0.06.

[0076] 2) Slowly add the dissolved sodium hydroxide and thiourea mixture to the zinc acetate dihydrate ethanol solution. After the addition is complete, stir at room temperature for 35 minutes.

[0077] 3) Transfer the above mixed solution to a 100 ml high-pressure reactor and hydrothermally incubate at 160 °C for 26 h. After the reaction, allow the reactor to cool to room temperature (25 °C), collect the product, and then add 40 ml of a mixture of deionized water and ethanol (volume ratio 1:1). Centrifuge at 5000 r / min for 6 min; repeat the process of mixing the centrifuged product with the same solution and centrifuging 5 times. Then dry in a vacuum drying oven at 60 °C for 10 h to obtain sulfur-doped zinc oxide nanoparticles with piezoelectric photocatalytic degradation properties.

[0078] Comparative Example 5

[0079] A method for preparing sulfur-doped zinc oxide nanoparticles includes the following steps:

[0080] 1) Weigh 6.4 g of sodium hydroxide and 0.03 g of thiourea and dissolve them in 30 ml of ethanol. Stir until dissolved. Then weigh 1.098 g of zinc acetate dihydrate and add it to 20 ml of ethanol and stir. The molar ratio of hydroxide to zinc atoms is 32 and the molar ratio of sulfur atoms to zinc atoms is 0.08.

[0081] 2) Slowly add the dissolved sodium hydroxide and thiourea mixture to the zinc acetate dihydrate ethanol solution, and stir at room temperature for 1 hour after the addition is complete.

[0082] 3) Transfer the above mixed solution to a 100 ml high-pressure reactor and hydrothermally incubate at 160 °C for 26 h. After the reaction, allow the reactor to cool to room temperature (25 °C), collect the product, and then add 40 ml of a mixture of deionized water and ethanol (volume ratio 1:1). Centrifuge at 5000 r / min for 8 min. Repeat the process of mixing the centrifuged product with the same solution and centrifuging 4 times. Then dry in a vacuum drying oven at 70 °C for 10 h to obtain sulfur-doped zinc oxide nanoparticles with piezoelectric photocatalytic degradation properties.

[0083] Comparative Example 6

[0084] Nano zinc oxide, product number Z820773, manufactured by McLean Reagents, is a common commercial zinc oxide with a purity of 99.8%. This comparative example is a commercially available zinc oxide with piezoelectric photocatalytic properties synthesized using existing technology, and its particle size is approximately the same as that of the zinc oxide synthesized in Comparative Example 1.

[0085] Example 1

[0086] A method for preparing sulfur-doped zinc oxide nanomaterials with broad-spectrum piezoelectric photocatalytic degradation, comprising the following steps:

[0087] 1) Weigh 2 g of sodium hydroxide and 0.0375 g of thiourea and dissolve them in 30 ml of ethanol and 5 ml of deionized water. Stir until dissolved. Then weigh 1.098 g of zinc acetate dihydrate and add it to 20 ml of ethanol and stir. The molar ratio of hydroxide to zinc atoms is 10 and the molar ratio of sulfur atoms to zinc atoms is 0.1.

[0088] 2) Slowly add the dissolved sodium hydroxide and thiourea mixed solution dropwise to the zinc acetate dihydrate ethanol solution. After the addition is complete, stir at room temperature for 30 min to obtain the mixed solution.

[0089] 3) Transfer the above mixed solution to a 100 ml high-pressure reactor and hydrothermally incubate at 150 °C for 24 h. After the reaction, allow the reactor to cool to room temperature (25 °C), collect the product, and then add 40 ml of a deionized water and ethanol mixture (volume ratio 1:1). Centrifuge at 5000 r / min for 5 min. Collect the centrifuged product, add the above deionized water and ethanol mixture, and centrifuge again. Repeat the above steps four times. Then, dry in a vacuum drying oven at 60 °C for 8 h to obtain sulfur-doped zinc oxide nanomaterials with piezoelectric photocatalytic degradation properties.

[0090] Example 2

[0091] A method for preparing sulfur-doped zinc oxide nanomaterials with broad-spectrum piezoelectric photocatalytic degradation, comprising the following steps:

[0092] 1) Weigh 4 g of sodium hydroxide and 0.0225 g of thiourea and dissolve them in 30 ml of ethanol and 5 ml of deionized water. Stir until dissolved. Then weigh 1.098 g of zinc acetate dihydrate and add it to 20 ml of ethanol and stir. The molar ratio of hydroxide to zinc atoms is 20 and the molar ratio of sulfur atoms to zinc atoms is 0.06.

[0093] 2) Slowly add the dissolved sodium hydroxide and thiourea mixture to the zinc acetate dihydrate ethanol solution. After the addition is complete, stir at room temperature for 40 minutes to obtain the mixed solution.

[0094] 3) Transfer the above mixed solution to a 100 ml high-pressure reactor and hydrothermally incubate at 120 °C for 20 h. After the reaction, allow the reactor to cool to room temperature (25 °C), collect the product, and then add 60 ml of a deionized water and ethanol mixture (volume ratio 1:1). Centrifuge at 4000 r / min for 10 min. Collect the centrifuged product, add the above deionized water and ethanol mixture, and centrifuge again. Repeat the above steps twice. Then, dry in a vacuum drying oven at 65 °C for 10 h to obtain sulfur-doped zinc oxide nanomaterials with piezoelectric photocatalytic degradation properties.

[0095] Example 3

[0096] A method for preparing sulfur-doped zinc oxide nanomaterials with broad-spectrum piezoelectric photocatalytic degradation, comprising the following steps:

[0097] 1) Weigh 6 g of sodium hydroxide and 0.03 g of thiourea and dissolve them in 30 ml of ethanol and 5 ml of deionized water. Stir until dissolved. Then weigh 1.098 g of zinc acetate dihydrate and add it to 20 ml of ethanol and stir. The molar ratio of hydroxide to zinc atoms is 30 and the molar ratio of sulfur atoms to zinc atoms is 0.08.

[0098] 2) Slowly add the dissolved sodium hydroxide and thiourea mixed solution dropwise to the zinc acetate dihydrate ethanol solution. After the addition is complete, stir at room temperature for 1 hour to obtain the mixed solution.

[0099] 3) The above mixed solution was transferred to a 100 ml high-pressure reactor and hydrothermally heated at 180 °C for 26 h. After the reaction, the reactor was cooled to room temperature (25 °C), and the product was collected. Then, a 40 ml mixture of deionized water and ethanol (volume ratio 1:1) was added, and the mixture was centrifuged at 6000 r / min for 6 min. The centrifuged product was collected, and the above-mentioned deionized water and ethanol mixture was added, followed by centrifugation. This process was repeated four times. The product was then dried in a vacuum drying oven at 70 °C for 12 h to obtain sulfur-doped zinc oxide nanomaterials with piezoelectric photocatalytic degradation properties.

[0100] Figure 1The X-ray diffraction patterns of Comparative Examples 1, 3, 4, and 5, Examples 1, 2, and 3 are shown. The XRD diffraction peak data all correspond to the diffraction peaks of wurtzite zinc oxide (PDF#36-1451). Meanwhile, compared to the zinc oxide sample (Comparative Example 1), the diffraction peaks of the (101) crystal plane in the sulfur-doped sample shift towards a smaller angle. According to the Bragg equation 2dsinθ=nλ, a decrease in θ indicates an increase in the interplanar spacing d. This is because the atomic radius of sulfur is larger than that of oxygen atoms, and sulfur doping into the zinc oxide lattice increases the interplanar spacing. On the other hand, by comparing the intensity ratio of the (002) / (100) diffraction peaks, it was found that the intensity of the (002) diffraction peak in each example was significantly higher than in the other comparative examples. This indicates that as the molar ratio of hydroxide ions to zinc changes from 1 to (10-30), the synthesized sulfur-doped zinc oxide tends to grow along the c-axis, i.e., it grows along a one-dimensional nanorod structure. XRD patterns confirmed the successful synthesis of sulfur-doped zinc oxide of the wurtzite type.

[0101] Figure 2 Figures a, b, and c show the morphology and size of samples from Comparative Example 1, Comparative Example 2, and Example 1, respectively. It can be seen that the synthesized pure zinc oxide (Comparative Example 1) is hexagonal granular with a diameter of 50-70 nm; the synthesized sulfur-doped zinc oxide with a hydroxyl to zinc molar ratio of 1 (Comparative Example 3) is small granular with a diameter of approximately 10 nm; and the synthesized sulfur-doped zinc oxide with a hydroxyl to zinc molar ratio of 10 (Example 1) is rod-shaped with a length of approximately 50-100 nm and a diameter of approximately 10-20 nm.

[0102] Figure 3 The UV-Vis absorption spectra of the samples from Comparative Example 1 and Example 1 are shown. It can be seen that the absorption edge of the pure zinc oxide sample (Comparative Example 1) is 388 nm, with no absorption in the visible light region, while the sulfur-doped zinc oxide nanorods have an absorption edge of 418 nm, and their absorption region extends into the visible light region.

[0103] Figure 4 The electrochemical impedance spectroscopy (EIS) of Comparative Example 1 and Example 1 shows that, compared with pure zinc oxide, sulfur-doped zinc oxide nanorods have a smaller arc radius. The smaller the arc radius, the lower the charge transfer resistance and the higher the conductivity. Further, when sulfur-doped zinc oxide nanorods are subjected to light and ultrasound, their arc radius becomes even smaller. This indicates that light and ultrasound can promote the effective migration of photogenerated carriers inside the catalyst.

[0104] Figure 5 The graphs show the degradation curves of Acid Orange 7 under visible light irradiation and ultrasonic treatment for comparative examples and embodiments. Figure 6The bar chart shows the corresponding degradation kinetic coefficients. Under light and ultrasound, pure zinc oxide (Comparative Example 1) showed a degradation rate of 22% within 100 mins, while commercial zinc oxide (Comparative Example 6) only showed a degradation rate of 19%. The samples from the examples with sulfur doping and morphology modification significantly improved the piezoelectric photocatalytic activity of zinc oxide, with Example 1 showing a degradation rate of 67% within 100 mins. The degradation kinetic constants for Example 1 were 0.1072 mins. -1 It is pure zinc oxide (0.0204 min). -1 It is 5.25 times that of commercial zinc oxide (0.0175 min) and is more than that of commercial zinc oxide (0.0175 min). -1 The degradation rate was 6.12 times that of the comparative example. Furthermore, compared to the comparative example, the degradation rate of each embodiment was increased by at least 25%, and the degradation kinetic constant was increased by at least 3 times. This indicates that the synthesized sulfur-doped zinc oxide nanorods possess excellent piezoelectric photocatalytic degradation performance. Doping and morphology control significantly improved the optical and piezoelectric properties of zinc oxide, thereby enhancing its piezoelectric photocatalytic performance.

[0105] The materials obtained in Examples 1-3 were subjected to degradation tests under conditions of light and ultrasound, and light alone. The results are as follows: Figure 7 As shown, under light-only conditions, the degradation rate of 15 mg / L Acid Orange 7 in all embodiments was approximately 20% within 100 min. However, under both light and ultrasound conditions, the degradation rate increased to over 60%, a significant improvement of more than 40%, and the degradation kinetic constants were all increased by at least 8 times. The test results demonstrate that the sulfur-doped zinc oxide nanomaterials synthesized in this invention possess excellent piezoelectric photocatalytic degradation performance.

[0106] The materials obtained in Example 1, Comparative Example 1, and Comparative Example 6 were used to perform piezoelectric photocatalytic degradation of methyl orange (MO), ciprofloxacin (CIP), and tetracycline (TC), respectively. Figure 9 The degradation curves show that, compared to the degradation rates of pure zinc oxide (11%, 9%, and 27%, respectively) and commercial zinc oxide (9%, 11%, and 23%, respectively), the sulfur-doped zinc oxide nanorods obtained in Example 1 of this invention exhibit significantly better degradation capabilities for various dyes and antibiotics, with degradation rates of 33%, 40%, and 76% for methyl orange (MO), ciprofloxacin (CIP), and tetracycline (TC), respectively. Figure 10 Comparing the corresponding degradation kinetic constants, the degradation kinetic constants of sulfur-doped zinc oxide nanorods are 0.0384 min⁻¹. -1 0.0531 min -1 0.1534 min -1 This is greater than the degradation kinetic constant of pure zinc oxide (0.0116 min). -1 0.071 min -10.0303 min -1 The degradation kinetics were increased by 3.31, 7.48, and 5.06 times, respectively, which is higher than the degradation kinetic constant of commercial zinc oxide (0.0119 min). -1 0.093 min -1 0.0258 min -1 The values ​​were increased by 3.22, 5.71, and 5.94 times, respectively. Methyl orange (MO), ciprofloxacin (CIP), and tetracycline (TC) belong to different structures and different categories of pollutants. The above test results demonstrate that the sulfur-doped zinc oxide nanorods synthesized by this invention have excellent broad-spectrum piezoelectric photocatalytic degradation performance and can degrade a variety of pollutants.

[0107] The zinc oxide composite material synthesized by Chinese invention patent CN119327494A exhibits a 2×10⁻⁶ effect within 3 hours. -5 The degradation rate of mol / L methylene blue is over 60%. The copper-doped zinc oxide nanomaterials synthesized in Chinese invention patent CN119500277A showed a degradation rate of over 30% for Rhodamine B within 4 hours, while the sulfur-doped zinc oxide material synthesized in Chinese invention patent CN108298575B showed a degradation rate of 20% for methyl orange. However, the sulfur-doped zinc oxide nanomaterials obtained in this invention achieved degradation rates of over 60%, 30%, and 70% for 15 mg / L Acid Orange 7, methyl orange, and tetracycline, respectively, within 100 minutes. Compared with existing technologies, the sulfur-doped zinc oxide nanomaterials obtained in this invention exhibit outstanding and excellent catalytic degradation performance.

[0108] This invention employs a simple, low-cost one-step hydrothermal synthesis method to synthesize sulfur-doped zinc oxide nanomaterials. This material exhibits responsive absorption in the visible light region. Compared to the relatively low piezoelectric photocatalytic performance and limited ability to degrade a single type of pollutant compared to pure zinc oxide, the material synthesized in this invention significantly enhances the piezoelectric photocatalytic performance of zinc oxide and expands the range of pollutants it can degrade. Compared to commercially available zinc oxide, it possesses superior piezoelectric photocatalytic performance, achieving broad-spectrum degradation characteristics. The sulfur-doped zinc oxide nanomaterials synthesized in this invention show promising applications in environmental remediation and energy conversion.

[0109] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A sulfur-doped zinc oxide nanomaterial with broad-spectrum piezoelectric photocatalytic degradation properties, characterized in that: An ethanol mixture of an alkali source and a sulfur source is added to an ethanol solution of a zinc source. The mixture is stirred at room temperature for 0.5-1 h, then transferred to a high-pressure reactor and hydrothermally reacted at 120-160℃ for 18-26 h. The mixture is then cooled, washed, and dried to obtain the final product. The molar ratio of the alkali source to the zinc source is (10-30):

1. The sulfur source is one or more of thiourea, thioacetamide, and sodium sulfide.

2. The sulfur-doped zinc oxide nanomaterial with broad-spectrum piezoelectric photocatalytic degradation characteristics according to claim 1, characterized in that: The alkaline source is one or more of sodium hydroxide, potassium hydroxide, and ammonia water.

3. The sulfur-doped zinc oxide nanomaterial with broad-spectrum piezoelectric photocatalytic degradation characteristics according to claim 1, characterized in that: The zinc source is one or more of zinc acetate, zinc nitrate, zinc chloride, and zinc sulfate.

4. The sulfur-doped zinc oxide nanomaterial with broad-spectrum piezoelectric photocatalytic degradation characteristics according to claim 1, characterized in that: The molar ratio of sulfur source to zinc source is (0.06-0.1):

1.

5. The sulfur-doped zinc oxide nanomaterial with broad-spectrum piezoelectric photocatalytic degradation characteristics according to claim 1, characterized in that: The cooling process involves naturally cooling the room temperature to 20-30°C.

6. The sulfur-doped zinc oxide nanomaterial with broad-spectrum piezoelectric photocatalytic degradation characteristics according to claim 1, characterized in that: The washing process involves cooling the reactants, thoroughly mixing the cooled product with a mixture of water and ethanol, and then centrifuging the mixture. Collect the centrifuged product, add a mixture of deionized water and ethanol, and centrifuge again; repeat the process of collecting the centrifuged product, adding a mixture of deionized water and ethanol, and centrifuging again; for a total of 2-4 times.

7. The sulfur-doped zinc oxide nanomaterial with broad-spectrum piezoelectric photocatalytic degradation characteristics according to claim 6, characterized in that: The mass ratio of the cooling product to the mixture is 1:(10-15); the volume ratio of water to ethanol is 1:1-2; the centrifugation speed is 4000-6000 r / mins; and the centrifugation time is 5-10 mins.

8. The sulfur-doped zinc oxide nanomaterial with broad-spectrum piezoelectric photocatalytic degradation characteristics according to claim 1, characterized in that: The drying process involves drying in a drying oven at 60-70℃ for 8-12 hours.

9. The method for preparing sulfur-doped zinc oxide nanomaterials with broad-spectrum piezoelectric photocatalytic degradation characteristics according to any one of claims 1-8, characterized in that... Includes the following steps: 1) Using ethanol as a solvent, add a mixed solution of alkali source and sulfur source to an ethanol solution of zinc source; 2) Stir the product obtained in step 1) uniformly at room temperature for 0.5-1h, and then transfer it to a high-pressure reactor for hydrothermal reaction at 120-160℃ for 18-26h. 3) Cool, wash and dry the product obtained in step 2) to obtain sulfur-doped zinc oxide nanomaterials with broad-spectrum piezoelectric photocatalytic degradation characteristics.

10. The application of the sulfur-doped zinc oxide nanomaterial with broad-spectrum piezoelectric photocatalytic degradation properties as described in any one of claims 1-8 in the degradation of organic dyes and antibiotics, characterized in that: The organic dyes are Acid Orange 7 and Methyl Orange, and the antibiotics are Tetracycline and Ciprofloxacin.

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