Precious metal platinum doped nano zinc oxide photocatalyst, preparation method and application
By using natural biological templates to assist microwave hydrothermal and in-situ photochemical reduction techniques, the complexity and high cost of the synthesis process of nano-zinc oxide photocatalysts were solved, and a high-efficiency, low-cost, and environmentally friendly noble metal platinum-doped nano-zinc oxide photocatalyst was prepared, which improved its photocatalytic and fluorescence performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHONGYUAN ENGINEERING COLLEGE
- Filing Date
- 2026-02-03
- Publication Date
- 2026-05-12
AI Technical Summary
Existing nano zinc oxide photocatalysts suffer from problems such as complex synthesis methods, high cost, high toxicity, and poor fluorescence stability, making it difficult to achieve photocatalytic materials with both high efficiency in degradation and fluorescence bifunctionality.
By employing natural biological templates combined with microwave-assisted hydrothermal and in-situ photochemical reduction techniques, uniform doping of noble metals in the hierarchical porous structure of ZnO was achieved. Through a process chain of template guidance, microwave rapid synthesis, in-situ photoreduction, and post-treatment stabilization, a noble metal platinum-doped nano-zinc oxide photocatalyst was prepared.
The synthesis cycle was significantly shortened, energy consumption was reduced, and noble metal nanoclusters with high specific surface area and uniform dispersion were prepared, which improved photocatalytic activity and fluorescence performance, thus realizing environmentally friendly high-performance photocatalytic materials.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst synthesis technology, and in particular to a noble metal platinum-doped nano zinc oxide photocatalyst, its preparation method, and its application. Background Technology
[0002] Zinc oxide is an inorganic oxide. By employing different synthesis methods and varying synthesis conditions, the nanoscale size of zinc oxide crystals can be controlled. Doping with different noble metal ions allows for the synthesis of various composite zinc oxide nanomaterials. Zinc oxide is widely used in the production of semiconductor catalysts, analytical reagents, plastics and rubber, food and paper products, and composite flame retardants due to its simple synthesis, clean and low-consumption nature, safety, non-toxicity, low cost, stability, and UV resistance. Given these excellent properties, endowing nano-zinc oxide photocatalytic materials with more functionality, such as fluorescence properties, will greatly expand their application areas and scope. Composite or doping modification can achieve multifunctionality of nano-zinc oxide; this method is low-consumption, environmentally friendly, inexpensive, and readily available, and can significantly improve the photocatalytic activity and fluorescence tracking performance of nano-zinc oxide. For example, composite nanopowder prepared by zinc oxide and Fe using the sol-gel method can improve the photocatalytic activity of nano zinc oxide, achieving a degradation rate of about 99.5% for methylene blue (MB). When nano zinc oxide is doped with an aqueous solution of noble metal platinum ions, it exhibits fluorescence detection performance and higher organic matter degradation effect compared to pure zinc oxide catalysts.
[0003] In 2018, a team at the Institute for Materials Science in Seville, Spain, prepared nano-zinc oxide with an average particle size of approximately 25-30 nm using a precipitation method. The Pt particles were 3-5 nm in size. This photocatalytic material achieved complete degradation of Rhodamine B (RhB) and methyl orange (MO) within 60 minutes. In 2020, Springer Nature Switzerland AG synthesized Ag into nano-zinc oxide materials at high temperatures using a co-precipitation method, obtaining zinc oxide rods with an average crystallite size of approximately 24-90 nm, and discovered their selective detection capability for ferric ions. However, previous studies on nano-zinc oxide primarily focused on precipitation and sol-gel methods, which are more complex, require more stringent conditions, and are more expensive than hydrothermal methods. Furthermore, there are currently no reports on photocatalytic degradation materials that simultaneously possess both high degradability and fluorescence bifunctionality.
[0004] Fluorescent functionalized zinc oxide nanomaterials hold promising applications in areas such as detecting the degradation effects of environmental pollutants, biomedical imaging, and drug delivery tracking systems. Currently, the fluorescent additives used in the preparation of zinc oxide nanomaterials are mostly organic fluorescent dyes, carbon quantum dots, and semiconductor quantum dots. These additives often suffer from drawbacks such as significant toxicity, large size, and poor fluorescence stability. Therefore, finding novel, non-toxic, and environmentally friendly zinc oxide nanocomposite / doped materials is of profound significance.
[0005] Therefore, this invention is proposed. Summary of the Invention
[0006] To address the aforementioned technical problems, this invention provides a platinum-doped nano-zinc oxide photocatalyst, its preparation method, and its application. By employing a natural biological template combined with microwave-assisted hydrothermal and in-situ photochemical reduction techniques, uniform doping of ultra-low-precious metals (Pt, Pd, Au, etc.) in a hierarchical porous structure of ZnO is achieved, simultaneously completing material morphology regulation and active site construction.
[0007] In order to achieve the objective of this invention, the following technical solution is adopted: This invention provides a method for preparing a platinum-doped nano-zinc oxide photocatalyst, comprising the following steps: S1. Natural biomaterials with hierarchical porous structures are used as soft templates for pretreatment, followed by freeze-drying to obtain Zn. 2+ Loaded biological templates; S2. The template is placed in a mixed solvent, and ZnO@biotemplate is synthesized by microwave hydrothermal synthesis and then washed by centrifugation. S3. Prepare a doping solution containing noble metal ions, dissolve the ZnO@biotemplate in the doping solution containing noble metal ions, and irradiate it under ultraviolet light; S4. Calcine in air, then immerse the product in sodium citrate solution to obtain the catalyst.
[0008] Furthermore, the hierarchical porous natural biomaterial in S1 is any one of lotus pollen, rose pollen, or calcium alginate microspheres.
[0009] Furthermore, the pretreatment of S1 specifically includes the following steps: immersing the biological template in a Zn(NO3)2 solution and ultrasonically vibrating it.
[0010] Furthermore, the ultrasonic oscillation time is 20-35 minutes.
[0011] Furthermore, the specific steps of microwave hydrothermal heating in S2 include: setting the microwave power to 400W-600W and heating at 150℃-170℃ for 25min-35min.
[0012] Furthermore, the microwave power is 500W, and the heating is carried out at 160℃ for 30 minutes.
[0013] Furthermore, the doped solution containing noble metal ions in S3 specifically comprises: dissolving chloroplatinic acid or chloroauric acid in ethylene glycol to prepare a solution with a concentration of 10. -5 -10 -4 A solution of M.
[0014] Furthermore, in step S3, the loading of precious metals is maintained at 0.001wt%-0.05wt% by adjusting the duration of ultraviolet irradiation.
[0015] Furthermore, when the loading is low (0.001wt%-0.01wt%), the illumination time is 30min-60min, and the concentration of the dopant solution is 10. -5 M; When the loading is high (0.01wt%-0.05wt%), the illumination time is controlled between 60min and 120min, while the concentration of the dopant solution is 10. -4 M.
[0016] Furthermore, the calcination temperature in S4 is 250℃-350℃ for 2-3 hours; The concentration of the sodium citrate solution is 0.1M. The product is immersed in the sodium citrate solution and then treated at 55℃-65℃ for 0.5h-1h.
[0017] Furthermore, the calcination temperature in S4 is 300°C, and the calcination time is 2 hours.
[0018] Furthermore, the mixed solvent is a mixture of ethanol and water with a concentration of 0.05M NaOH; wherein the volume ratio of ethanol to water is 1:1.
[0019] The present invention also provides a zinc oxide photocatalyst prepared by the above preparation method.
[0020] This invention also provides the application of the above-mentioned zinc oxide photocatalyst in the degradation of environmental water pollution, self-cleaning finishing of textiles, or detection of pollutant targets.
[0021] The present invention has the following technical effects: The green template-assisted—microwave hydrothermal—in-situ reduction one-step method proposed in this invention demonstrates significant technical advantages in the preparation of ultra-low noble metal doped ZnO-based composite photocatalysts. This method, by using a natural biological template and combining rapid microwave heating with ultraviolet light-induced in-situ reduction, achieves high efficiency, energy saving, and greening of the catalyst preparation process. Compared to the traditional long-duration hydrothermal method, the synthesis cycle is significantly shortened from over 6 hours to less than 3 hours, and energy consumption is significantly reduced. The prepared catalyst not only perfectly replicates the fine hierarchical porous structure of the biological template, possessing an extremely high specific surface area and providing abundant sites for pollutant adsorption and reaction, but also achieves highly uniform dispersion of ultra-low noble metal nanoclusters on the ZnO support, effectively constructing Schottky junctions and greatly promoting the separation and migration of photogenerated electron-hole pairs. Furthermore, this method avoids the use of highly toxic chemical reducing agents, and the process conditions are mild and controllable, providing a practical new approach for the large-scale preparation of high-performance, low-cost, and environmentally friendly photocatalytic materials. Attached Figure Description
[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0023] Figure 1 The results of characterizing the structure and composition of Pt-F2, among which, Figure 1 a is the FT-IR spectrum; Figure 1 b is the Raman spectrum; Figure 1 c is the XRD spectrum; Figure 1 d represents the XPS spectrum of Pt-F2; Figure 1 e represents the high-resolution XPS spectrum of the C1s peak; Figure 1 f is the high-resolution XPS spectrum of the O1s peak; g is the Zn peak. 2p High-resolution XPS spectra of the peaks; Figure h shows the Pt peaks. 4p High-resolution XPS spectra of the peaks; Figure 2 : This is a three-dimensional histogram of Pt-F2 after five cycles with four different dyes, where, Figure 2 a is a three-dimensional histogram of Pt-F2 after five iterations of the MB loop; Figure 2 b is a three-dimensional histogram of Pt-F2 after five cycles of Rh B; Figure 2 c is a three-dimensional histogram of Pt-F2 after five cycles of Mo; Figure 2 d is a three-dimensional bar chart of Pt-F2 after five cycles of the ATT loop. Detailed Implementation
[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0025] In a first aspect, the present invention provides a method for preparing a platinum-doped nano-zinc oxide photocatalyst, comprising the following steps: S1. Natural biomaterials with hierarchical porous structures are used as soft templates for pretreatment, followed by freeze-drying to obtain Zn. 2+ Loaded biological templates; S2. The template is placed in a mixed solvent, and ZnO@biotemplate is synthesized by microwave hydrothermal synthesis and then washed by centrifugation. S3. Prepare a doping solution containing noble metal ions, dissolve the ZnO@biotemplate in the doping solution containing noble metal ions, and irradiate it under ultraviolet light; S4. Calcine in air, then immerse the product in citric acid solution to obtain the catalyst.
[0026] This method constructs a complete process chain of "template-guided-microwave rapid synthesis-in-situ photoreduction doping-post-processing stabilization".
[0027] Template Direction and Adsorption (S1): Utilizing the inherent, precise hierarchical porous structure of natural biomaterials as a soft template. Through impregnation and ultrasound, zinc ions (Zn) are directed and adsorbed... 2+ The precursor is adsorbed and uniformly distributed on the pore surface and inside of the template, laying the morphological and structural foundation for the subsequent confined growth of ZnO.
[0028] Microwave rapid crystallization (S2): In a microwave field, polar molecules (such as water and ethanol) undergo high-frequency orientational motion, generating internal frictional heat and achieving rapid and uniform heating of the bulk phase. This greatly accelerates the nucleation and crystal growth kinetics of ZnO, prompting the ZnO precursor to be transformed in situ into well-crystallized ZnO on the template surface, and "replicating" the complex multi-level structure of the template to form a ZnO@biotemplate composite material.
[0029] In-situ photoreduction doping (S3): This is key to achieving ultra-low, uniform doping. Under ultraviolet light irradiation, ZnO is excited to generate photogenerated electrons (electrons). - ) and holes (h + These photogenerated electrons, with their strong reducing properties, can directly reduce noble metal ions (such as Pt) in the dopant solution in situ.4+ This process deposits the precious metals as atoms or nanoclusters on the surface or near-surface defect sites of ZnO. This process is carried out at room temperature or low temperature, avoiding the agglomeration of precious metals at high temperatures.
[0030] Template Removal and Surface Modification (S4): Low-temperature calcination effectively removes the organic biological template, exposing the high specific surface area and hierarchical porous ZnO framework replicated from the template. It also further enhances the crystallinity of ZnO and noble metals, resulting in a stronger interfacial bond. Subsequent citric acid treatment is a surface passivation strategy. Citrate ions can adsorb onto the catalyst surface, modifying its hydrophilicity and potentially stabilizing surface metal sites through complexation, reducing the loss of active components and thus enhancing the material's stability in aqueous reactions.
[0031] This method significantly shortens the reaction time (from over 6 hours in traditional hydrothermal methods to about 30 minutes) and reduces energy consumption through microwave heating. Utilizing the fine structure of the biological template, hierarchical porous ZnO with high specific surface area and abundant pores can be prepared, which is beneficial for reactant adsorption and mass transfer. Photochemical reduction achieves atomic-level dispersion and firm anchoring of noble metals on the ZnO support, avoiding agglomeration caused by physical mixing or high-temperature reduction, maximizing the utilization efficiency of noble metals and the construction effect of Schottky junctions. Simultaneously, the use of a natural template avoids complex organic template agents; and the use of photoreduction avoids the use of strong chemical reducing agents (such as sodium borohydride), making the process more environmentally friendly.
[0032] In some embodiments, the hierarchical porous natural biomaterial in S1 is any one of lotus pollen, rose pollen, or calcium alginate microspheres.
[0033] Lotus pollen and rose pollen typically possess regular and complex porous outer wall structures; calcium alginate microspheres, on the other hand, exhibit an internal three-dimensional network gel structure that can be controlled through preparation conditions. These materials are all natural products, and their pore structures vary across the micrometer to nanometer scales, providing unique spatial confinement and structural guidance for ZnO growth. Using these templates, ZnO-based catalysts with biomimetic fine structures can be prepared reproducibly and predictably. Their high specific surface area and hierarchical pores facilitate the exposure of more active sites and promote the diffusion of pollutant molecules within the catalyst, thereby enhancing catalytic efficiency.
[0034] In some embodiments, the pretreatment of S1 specifically includes the following steps: immersing the biological template in a Zn(NO3)2 solution and ultrasonically oscillating it.
[0035] In some embodiments, the ultrasonic oscillation time is 20-35 minutes.
[0036] Immersing a biological template in a zinc salt solution and subjecting it to ultrasonic oscillation is a process that enhances mass transfer using physical means. The cavitation effect generated by ultrasound produces localized high pressure and microjets, powerfully driving the Zn... 2+ The solution penetrates into the deep pores of the template and promotes the growth of Zn. 2+ It adsorbs more evenly on all available surfaces of the template, overcoming the concentration gradient and uneven adsorption problems that may occur during static soaking.
[0037] This ensures uniform and high loading of the zinc precursor in the template, guaranteeing the subsequent formation of a uniform and continuous ZnO coating or skeleton. This is a crucial prerequisite step for achieving structural integrity and performance uniformity in the final product.
[0038] In some embodiments, the specific steps of microwave hydrothermal heating in S2 include: setting the microwave power to 400W-600W and heating at 150℃-170℃ for 25min-35min.
[0039] In some embodiments, the microwave power is 500W, and the heating is carried out at 160°C for 30 minutes.
[0040] The power (400W-600W) and temperature (150℃-170℃) ranges define the microwave field strength and reaction temperature that provide sufficient energy to drive ZnO crystallization. The time (25min-35min) balances the relationship between sufficient crystal growth and preventing overgrowth leading to structural collapse or excessive template decomposition. Within this optimized range, microwave energy is efficiently converted into heat energy, promoting Zn(OH)₄ crystal growth. 2- The precursor undergoes rapid dehydration and condensation to form ZnO with good crystallinity and controlled morphology.
[0041] It provides a clear and operable process window. Within this parameter range, rapid and controllable crystallization of ZnO can be achieved, ensuring the acquisition of ZnO@biotemplate intermediates with ideal crystal phases (mainly wurtzite structure) and replicated template morphology in a short time, while avoiding energy waste or template structure damage caused by excessive time or temperature.
[0042] In some embodiments, the doped solution containing noble metal ions in S3 specifically comprises: dissolving chloroplatinic acid or chloroauric acid in ethylene glycol to prepare a solution with a concentration of 10. -5 -10 -4 A solution of M.
[0043] In some embodiments, the loading of precious metals in step S3 is maintained at 0.001wt%-0.05wt% by adjusting the duration of ultraviolet irradiation.
[0044] In some embodiments, when the loading is low (0.001wt%-0.01wt%), the illumination time is 30-60 minutes, and the concentration of the dopant solution is 10. -5 M; When the loading is high (0.01wt%-0.05wt%), the illumination time is controlled between 60min and 120min, while the concentration of the dopant solution is 10. -4 M.
[0045] Using ethylene glycol as a solvent is crucial. Ethylene glycol is not only a good solvent, but its hydroxyl groups (-OH) possess reducing and complexing abilities, which can help stabilize noble metal ions during photoreduction and may participate in the reaction, contributing to the formation of smaller, more dispersed noble metal nanoparticles. Maintaining a concentration of 10... -5 -10 -4 The low range of M is to match the goal of "ultra-low doping" by directly and precisely controlling the loading of noble metals in the final product by controlling the precursor concentration.
[0046] Precise and ultra-low control of noble metal loading (typically down to 0.01 wt% or even lower) was achieved. The ethylene glycol environment promoted the dispersion of noble metal nanoparticles, avoiding agglomeration caused by excessively rapid reduction at high concentrations. The ultra-low loading significantly improved the efficiency of photogenerated charge separation (through the formation of a Schottky barrier) while greatly reducing catalyst costs, thus enhancing its economics and practicality.
[0047] In some embodiments, the calcination temperature in S4 is 250℃-350℃ for 2-3 hours; The concentration of the sodium citrate solution is 0.1M. The product is immersed in the sodium citrate solution and then treated at 55℃-65℃ for 0.5h-1h.
[0048] In some embodiments, the calcination temperature in S4 is 300°C and the calcination time is 2 hours.
[0049] The selection of calcination temperature (250℃-350℃) and time (2h-3h) must meet two objectives: first, sufficient to carbonize or oxidize and decompose the organic biological template, completely removing it and exposing the porous ZnO structure; second, the temperature should not be too high to prevent excessive growth of ZnO grains, pore collapse, or sintering and agglomeration of noble metal particles. Sodium citrate treatment (0.1M, 55℃-65℃, 0.5h-1h) utilizes the coordination of the polycarboxyl groups of sodium citrate with the ZnO and noble metal surfaces to modify the surface chemical properties.
[0050] Mild calcination successfully achieved a balance between template removal and structural stabilization, yielding a porous framework with high specific surface area and good crystallinity. Surface treatment with sodium citrate further optimized the catalyst's surface properties, potentially enhancing its dispersibility in aqueous solution, passivating surface defects to reduce nonradiative recombination of photogenerated carriers, and possibly slightly altering the electronic state of the noble metal by forming metal-citric acid complexes, thereby jointly improving the catalyst's activity and cycle stability.
[0051] In some embodiments, the mixed solvent is a mixture of ethanol and water with a concentration of 0.05M NaOH; wherein the volume ratio of ethanol to water is 1:1.
[0052] The solvent system consists of ethanol, water, and NaOH. Water is the primary reaction medium; the addition of ethanol can adjust the dielectric constant and viscosity of the solution, affecting the microwave absorption efficiency and the solubility of the precursor, and may also act as a morphology modifier; NaOH provides the necessary alkaline environment (OH-). - ), and Zn 2+ The reaction produces Zn(OH)4 2- Isosoluble zincates are key precursor species for the hydrothermal synthesis of ZnO. A volume ratio of 1:1 is an optimized ratio that balances reactivity and protection of the template structure.
[0053] This mixed solvent system creates an ideal chemical environment for the uniform nucleation and growth of ZnO. It ensures the full dissolution and reaction of the zinc precursor, while the suitable solvent properties help achieve a uniform temperature distribution during microwave heating and may regulate the growth rate of different crystal facets during crystal growth, thereby contributing to the formation of ZnO nanostructures with specific exposed crystal facets and high photocatalytic activity.
[0054] The present invention also provides a zinc oxide photocatalyst prepared by the above preparation method.
[0055] This invention also provides the application of the above-mentioned zinc oxide photocatalyst in the degradation of environmental water pollution, self-cleaning finishing of textiles, or detection of pollutant targets.
[0056] The following is a detailed explanation using specific embodiments: Example 1 S1. A natural biomaterial with a hierarchical porous structure (calcium alginate in this embodiment) is used as a soft template; the template is immersed in a 0.1M Zn(NO3)2 solution and ultrasonically vibrated for 30 minutes to allow the Zn... 2+ The Zn nanoparticles were fully adsorbed onto the template surface and into the pores; after freezing at -50℃ for 12 hours, they were freeze-dried to obtain Zn. 2+ Loaded biological template.
[0057] S2, Zn 2+The supported biological template was placed in an ethanol-water mixed solvent containing 0.05 M NaOH (volume ratio 1:1); microwaved at 500 W, 160 °C, for 30 min, followed by centrifugation and washing.
[0058] S3. Dissolve chloroplatinic acid in ethylene glycol to prepare a solution with a concentration of 10. -4 When the doped solution of M is irradiated with ultraviolet light (λ=365nm) for 120 min, noble metal ions are reduced in situ to nanoclusters on the ZnO surface. S4. Calcine at 300℃ for 2 hours in air to remove the biological template and avoid excessive growth of ZnO lattice. Immerse the product in 0.1 M sodium citrate solution and treat at 60℃ for 1 hour to enhance surface hydrophilicity and photostability, thus preparing Pt-ZnO with a loading of 0.01%, denoted as Pt-F2.
[0059] Example 2 The specific implementation method is consistent with Example 1, except that the natural biomaterial with a hierarchical porous structure is replaced with lotus pollen.
[0060] Example 3 The specific implementation method is consistent with Example 1, except that step S3 is replaced by: dissolving chloroplatinic acid in ethylene glycol to prepare a solution with a concentration of 10. -5 The dopant solution of M was irradiated with ultraviolet light (λ=365nm) for 30 minutes.
[0061] Experimental Example 1: Characterization of the structure and composition of Pt-ZnO The structure and composition of Pt-ZnO were characterized. The FT-IR spectra of pure zinc oxide and Pt-ZnO are shown below. Figure 1 As shown in a. 3400cm -1 The absorption peak at 1570 cm⁻¹ is caused by the symmetric stretching vibration of the -OH group of water on the zinc oxide surface. -1 and 1408cm -1 The spectral bands at this location correspond to the stretching vibrations of carboxyl groups at different sites. 1041 cm⁻¹ -1 and 873cm -1 The absorption peak at that point is caused by the OH bending vibration. Clearly, the doping of nano-Pt did not alter the structure of zinc oxide. This was confirmed by Raman spectroscopy (…). Figure 1 b) The crystal structures of the zinc oxide and Pt-ZnO heterostructures were clarified. 440 cm⁻¹ -1 The distinct peak at 337 cm⁻¹ represents the nonpolar optical phonon of hexagonal zinc oxide. -1 and 580cm -1The peaks at these locations represent the A1 (transverse optical, TO) mode and the E1 (longitudinal optical, LO) mode, respectively. The low intensity of the E1 (LO) peak indicates a low oxygen vacancy density. There is no significant difference between pure zinc oxide and Pt-ZnO (no Pt-related peaks appear), which is consistent with the low chemical content of Pt. The XRD results of pure zinc oxide and Pt-ZnO samples are shown below. Figure 1 As shown in c. The structure of the Pt-ZnO catalyst is confirmed. The intensity peaks at 31.63, 34.33, 36.18, 47.39, 56.48, 66.39, and 67.89 correspond to the (100), (002), (101), (102), (110), (220), and (112) crystal planes of Pt-ZnO, respectively. The entire XRD pattern confirms the presence of zinc oxide, and the peaks of the Pt-ZnO sample are slightly shifted, indicating that the crystal structure of zinc oxide has undergone a slight change due to the low doping concentration. XPS tests were used to study the elemental composition and its corresponding valence states, such as Figure 1 As shown in d. The Pt-ZnO sample is composed of four elements: C, O, Zn, and Pt; no significant peaks were found for the other elements. The test spectrum modified with a binding energy of 284.8 eV at C1s shows the detailed spectra of each element, as follows: Figure 1 As shown in the figure. The lattice oxygen and oxygen defect sites of the best sample are 529.37 eV and 531.20 eV, respectively, under the fine spectral fitting of O1. The fine spectral fitting results of zinc show that Pt-ZnO(2p) corresponds to the 2p and Zn 2p electronic states, with energies of 1020.7 eV and 1044.8 eV, respectively, and exists in Zn. 2+ In chemical state.
[0062] Experimental Example 2: Evaluation of Cyclic Degradation Experimental results are as follows Figure 2 As shown, the catalyst prepared in Example 1 was used to conduct five consecutive cycles of testing on four different organic dye solutions, with a reaction time of 90 minutes. From Figure 2As can be clearly seen from the data, the degradation ability of Pt-ZnO for MB (methylene blue) is not affected by repeated use, and a good degradation effect is achieved within about 30 minutes. Furthermore, the concentration of Rh B (rhodamine B) drops to approximately 68.3% in the fifth stage. The cyclic treatment ability of Pt-ZnO for Mo (methyl orange) and ATT (acid black) decreases with increasing cycle number, significantly decreasing to 70.1% and 69.5% in the fourth and fifth stages, respectively. However, after five cycles, the average degradation rate of MB and Rh B dyes remains below 99.9% during repeated use, while the degradation rate of Mo and ATT dyes only reaches approximately 70.0%. After one photodegradation cycle, the catalyst becomes contaminated with dyes, and sample loss is difficult to avoid during washing and transfer. On the one hand, the reusability of the catalyst is affected by its surface characteristics and the availability of active sites; on the other hand, due to differences in dye molecular structure (such as the benzene ring structure in MB), electron transfer is more likely to occur. However, due to the presence of complex structures such as benzodiazole in Mo, the degradation effects of ATT and Mo are poor. Multiple factors may cause degradation intermediates to hinder subsequent catalytic reactions at the active sites of Pt-ZnO, thereby reducing the catalytic activity for repeated use.
[0063] Experimental Example 3: Evaluation of Photocatalytic Degradation Efficiency The degradation kinetics of four different dyes were analyzed using Pt-ZnO, and the results were obtained using a first-order kinetic model (Equation 1), as follows: Equation 1: Where C0 (mg / L) is the initial concentration of the dye, C t (mg / L) represents the concentration of the dye over time, and k1 (min) represents the concentration of the dye over time. -1 ) represents the reaction rate constant. k1 was obtained by measurement; for MB in visible light, k1 = 0.026, R 2 =0.892; Mo’s k1=0.011, R 2 =0.946; Rh B's k1=0.047, R 2 =0.976; ATT's k1=0.017, R 2 =0.929.
[0064] The catalysts prepared in Examples 1-3 were subjected to the same irradiation time (90 min) to catalyze the four pollutants in Experiment Example 2.
[0065] The measurements included: using a first-order reaction kinetic model, determining the degradation efficiency of mixed light and visible light, respectively; The experimental results are shown in Table 1.
[0066] Table 1: Catalytic efficiency evaluation of Examples 1-3 Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing a platinum-doped nano-zinc oxide photocatalyst, characterized in that, Includes the following steps: S1. Natural biomaterials with hierarchical porous structures are used as soft templates for pretreatment, followed by freeze-drying to obtain Zn. 2+ Loaded biological templates; S2. The template is placed in a mixed solvent, and ZnO@biological template is synthesized by microwave hydrothermal synthesis, followed by centrifugation and washing. S3. Prepare a doping solution containing noble metal ions, dissolve the ZnO@biotemplate in the doping solution containing noble metal ions, and irradiate it under ultraviolet light; S4. Calcine in air, then immerse the product in sodium citrate solution to obtain the catalyst.
2. The method for preparing the noble metal platinum-doped nano-zinc oxide photocatalyst according to claim 1, characterized in that, The hierarchical porous natural biomaterial in S1 is any one of lotus pollen, rose pollen, or calcium alginate microspheres.
3. The method for preparing the noble metal platinum-doped nano-zinc oxide photocatalyst according to claim 1, characterized in that, The pretreatment of S1 specifically includes the following steps: immersing the biological template in a Zn(NO3)2 solution and ultrasonically vibrating it.
4. The method for preparing the noble metal platinum-doped nano-zinc oxide photocatalyst according to claim 1, characterized in that, The specific steps of microwave hydrothermal heating in S2 include: setting the microwave power to 400W-600W and heating at 150℃-170℃ for 25min-35min.
5. The method for preparing the noble metal platinum-doped nano-zinc oxide photocatalyst according to claim 1, characterized in that, The doped solution containing noble metal ions in S3 is specifically prepared by dissolving chloroplatinic acid or chloroauric acid in ethylene glycol to a concentration of 10. -5 -10 -4 A solution of M.
6. The method for preparing the noble metal platinum-doped nano-zinc oxide photocatalyst according to claim 1, characterized in that, The calcination temperature in S4 is 250℃-350℃ for 2-3 hours; The concentration of the sodium citrate solution is 0.1M. The product is immersed in the sodium citrate solution and then treated at 55℃-65℃ for 0.5h-1h.
7. The method for preparing the noble metal platinum-doped nano-zinc oxide photocatalyst according to claim 1, characterized in that, The mixed solvent is a mixture of ethanol and water with a concentration of 0.05M NaOH; wherein the volume ratio of ethanol to water is 1:
1.
8. A zinc oxide photocatalyst prepared by the method for preparing noble metal platinum-doped nano zinc oxide photocatalyst as described in any one of claims 1-7.
9. The application of the zinc oxide photocatalyst as described in claim 8 in the degradation of environmental water pollution, self-cleaning finishing of textiles, or detection of target pollutants.