A samarium-doped carbon quantum dot-based inverse opal material, a preparation method therefor and applications thereof

Abstract

The application belongs to the technical field of new functional materials and pollutant degradation, and particularly relates to a samarium-doped carbon quantum dot-based inverse opal material and a preparation method and application thereof. The samarium-doped carbon quantum dot-based inverse opal material is formed by using samarium-doped carbon quantum dots as a building unit and performing calcination etching on a silicon dioxide photonic crystal template. The material fully utilizes the structural advantages of high surface active site density and multi-coordination environment of the carbon quantum dots, realizes high density and uniform dispersion of the samarium element in the material, and enhances multiple scattering of light in the material and local light field effect, significantly expands the response capability of the material to near-infrared light, breaks through the limitation that traditional photocatalytic materials mainly depend on ultraviolet light or visible light, and improves the utilization efficiency of low-energy light. Under the condition of near-infrared light irradiation, the material exhibits excellent degradation performance on antibiotic organic pollutants, and raw materials are easy to obtain, the preparation process is simple, and the material has good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of novel functional materials and pollutant degradation technology. Specifically, it relates to a samarium-doped carbon quantum dot-based inverse opal material, its preparation method, and its application. Background Technology

[0002] With the widespread use of antibiotics in medicine, animal husbandry, and aquaculture, their residues in the environment are becoming increasingly prominent. Antibiotic pollutants are structurally stable and poorly biodegradable, easily accumulating in water bodies over long periods. This not only poses potential harm to aquatic ecosystems but may also induce the emergence of drug-resistant microorganisms, making it one of the most pressing issues to be addressed in the field of water environment management.

[0003] Advanced oxidation technologies (AEOs) have shown promising applications in the removal of recalcitrant organic pollutants such as antibiotics due to their ability to generate highly reactive oxidizing species. However, most existing photo-driven AEO systems rely primarily on ultraviolet (UV) or visible light excitation, limiting their photoresponse range. Furthermore, UV light constitutes a relatively small proportion of natural light and has limited penetration, hindering the widespread application of these technologies under practical environmental conditions. Therefore, expanding the photoresponse wavelength range and improving the utilization efficiency of low-energy light are key technical challenges currently facing the field of photocatalytic AEOs.

[0004] Near-infrared light constitutes a large proportion of the solar spectrum and has advantages such as strong penetration and good environmental adaptability. However, due to the low photon energy of near-infrared light, traditional photocatalytic materials are difficult to effectively excite under near-infrared light conditions, resulting in relatively few studies on their application in antibiotic pollution control. How to construct functional materials with near-infrared light response capabilities to achieve efficient degradation of antibiotics under near-infrared light conditions remains a technical challenge that urgently needs to be overcome.

[0005] Therefore, developing a novel functional material that can effectively respond to near-infrared light irradiation and be used for the degradation of antibiotic-like organic pollutants has significant research value and application prospects. Summary of the Invention

[0006] To address the limitations of existing photocatalytic materials in the near-infrared light response range and low catalytic degradation efficiency of organic pollutants, this invention aims to provide a samarium-doped carbon quantum dot-based inverse opal material capable of achieving efficient degradation of organic pollutants under infrared light irradiation, along with its preparation method and applications. By constructing a porous samarium-doped carbon quantum dot-based inverse opal material, the light response range of the material is extended to the near-infrared region (>800 nm), thereby improving the light energy utilization efficiency and catalytic degradation performance of pollutants under low-energy light conditions.

[0007] Based on the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a samarium-doped carbon quantum dot-based inverse opal material, which is formed by calcination and etching using samarium-doped carbon quantum dots as building blocks and silicon dioxide photonic crystal as a template. The samarium-doped carbon quantum dot-based inverse opal material has a three-dimensional porous structure with a pore size of 300-350 nm. The samarium doping content in the material is 10-40 wt%, preferably 15-30 wt%, and more preferably 25 wt%. The material has near-infrared light response performance and has broad-spectrum absorption characteristics in the 200-1400 nm wavelength range.

[0008] The samarium-doped carbon quantum dot-based inverse opal material claimed in this invention fully utilizes the structural advantages of high surface active site density and multi-coordination environment of carbon quantum dots to achieve high-density and uniform dispersion of samarium in the material, thereby improving the utilization efficiency of coordination species. The inverse opal structure enhances multiple scattering and localized optical field effects within the material, significantly extending its response to near-infrared light. Under near-infrared light irradiation, this material exhibits excellent degradation performance for antibiotic-like organic pollutants, demonstrating highly efficient photocatalytic properties.

[0009] Secondly, the present invention provides a method for preparing the above-mentioned samarium-doped carbon quantum dot-based inverse opal material, comprising the following steps: S1: Synthesis of silicon dioxide photonic crystal template Using tetraethyl silicate as a precursor, a hydrolysis-condensation reaction is carried out under the action of a weak alkaline catalyst to form a sol, which is then centrifuged, encapsulated into colloidal crystals, and dried to obtain a silica photonic crystal template. S2: Synthesis of carbon quantum dot powder Citric acid and ethylenediamine were reacted hydrothermally, and the resulting product was concentrated and dried to obtain carbon quantum dot powder. S3: Synthesis of Samarium-Doped Carbon Quantum Dots Samarium source was subjected to hydrothermal reaction with carbon quantum dot powder, and the resulting product was concentrated and dried to obtain samarium-doped carbon quantum dot powder. S4: Synthesis of Samarium-doped carbon quantum dot-based inverse opal After mixing the samarium-doped carbon quantum dot powder from step S3 with the silicon dioxide photonic crystal template from step S1, the mixture is calcined. The calcined product is then subjected to alkaline etching to obtain samarium-doped carbon quantum dot-based inverse opal.

[0010] This invention uses carbon quantum dots as building blocks and silicon dioxide photonic crystals as templates. By introducing samarium and combining it with calcination and etching processes, carbon quantum dots can be self-constructed to form a three-dimensional inverse opal structure. The preparation method is simple and controllable.

[0011] Carbon quantum dots possess tunable energy level structures and excellent optical properties. By introducing rare earth elements (such as samarium, lanthanum, cerium, and ytterbium) into carbon quantum dots for doping, their electronic structure and photogenerated carrier behavior can be further modulated. The inverse opal structure, with its porous structure and photon modulation characteristics, enhances light-harvesting ability and promotes reaction mass transfer, further improving the photocatalytic efficiency of the material. The material prepared in this invention extends the light response range to the near-infrared region (>800 nm), exhibiting excellent near-infrared light response characteristics. Under near-infrared light irradiation, it demonstrates excellent catalytic degradation performance for organic pollutants, improving light energy utilization efficiency and pollutant degradation performance under low-energy light conditions.

[0012] Preferably, in step S1, the weakly alkaline catalyst is ammonia.

[0013] Preferably, in step S2, the molar ratio of citric acid to ethylenediamine is 0.8–1.2:1, more preferably 1:1. When the ratio of citric acid to ethylenediamine is too high, there is insufficient nitrogen source in the system, resulting in a low degree of nitrogen doping in the formed carbon quantum dots, which is not conducive to controlling their band structure and electron transport performance, thereby reducing photocatalytic activity. When the ratio of citric acid to ethylenediamine is too low, excessive nitrogen source may lead to too many surface defects or structural instability of the carbon quantum dots, and it is also prone to side reactions, which is not conducive to the photocatalytic reaction. When the molar ratio of citric acid to ethylenediamine is controlled within the range of 0.8–1.2:1, it is beneficial to obtain carbon quantum dots with stable structure and moderate nitrogen doping; more preferably, when the ratio is 1:1, the material has better light absorption performance and carrier separation efficiency, thus exhibiting better photocatalytic degradation performance.

[0014] Preferably, the hydrothermal reaction conditions in step S2 are: 180℃~200℃ for 5~8h; and the hydrothermal reaction conditions in step S3 are: 180℃~200℃ for 8~10h.

[0015] In steps S2 and S3, when the hydrothermal reaction temperature is below 180 °C, the carbonization and condensation reaction of the precursor is insufficient, making it difficult for carbon quantum dots to form fully. When the reaction temperature is in the range of 180–200 °C, it is beneficial for the precursor to react fully and form structurally stable and uniformly dispersed carbon quantum dots, while also promoting the effective introduction of samarium, thereby improving the near-infrared light response capability and photocatalytic activity of the material. When the reaction temperature is above 200 °C, excessively high temperatures may cause carbon quantum dots to undergo over-carbonization or agglomeration, affecting their dispersibility and surface active sites.

[0016] Preferably, the samarium source is a soluble trivalent samarium salt, preferably samarium chloride or samarium nitrate; the mass ratio of the carbon quantum dot powder to the samarium source is 1 to 9:1, more preferably 3:1.

[0017] Experiments revealed that catalysts with high catalytic degradation performance exhibited when the mass ratio of carbon quantum dot powder to samarium source was within the aforementioned range (1–9:1). When the samarium source ratio was too low, insufficient samarium content in the system made it difficult to effectively control the band structure and near-infrared light response of the material, resulting in low efficiency in photogenerated carrier generation and separation, thus weakening photocatalytic activity. When the samarium source ratio was too high, excess samarium tended to aggregate or act as recombination centers in the material, exacerbating photogenerated electron-hole recombination and potentially affecting the structural integrity of the carbon quantum dots, thereby reducing photocatalytic performance. A mass ratio of 1–9:1 for carbon quantum dot powder to samarium source effectively doped with samarium while maintaining the structural stability of the carbon quantum dots. A further preferred ratio of 3:1 resulted in a moderate degree of samarium doping, which enhanced the near-infrared light absorption capacity of the material and promoted carrier separation, thus exhibiting superior photocatalytic degradation performance.

[0018] Preferably, the mass ratio of samarium-doped carbon quantum dot powder to the silica photonic crystal template is 4–5:1. When the amount of samarium-doped carbon quantum dot powder is lower than the above ratio, the carbon source is insufficient, making it difficult to form a continuous and complete framework structure on the template surface. This results in an incomplete inverse opal structure or excessively thin pore walls, thereby affecting structural stability and the transport efficiency of photogenerated carriers. When the amount of samarium-doped carbon quantum dot powder is higher than the above ratio, excessive carbon source is prone to accumulate or blockage in the template pores, leading to uneven pore structure or even pore closure, reducing the specific surface area and mass transfer performance of the material. At the same time, it is not conducive to multiple scattering and utilization of light, thereby reducing the photocatalytic activity of the material.

[0019] Therefore, controlling the mass ratio of samarium-doped carbon quantum dot powder to silica template at 5:1 is beneficial to forming a three-dimensional ordered porous structure with complete structure, interconnected channels, and uniform distribution, thereby improving the light absorption capacity and photocatalytic degradation performance of the material.

[0020] Preferably, the calcination parameters in step S4 are: heating to 500-600°C at a heating rate of 5-10°C / min, and calcining at this temperature in an inert atmosphere for 3-4 hours.

[0021] When the calcination temperature is below 500℃, the carbon quantum dot structure is not fully developed, resulting in weak conductivity and light absorption, which is not conducive to the generation and transport of photogenerated carriers, thus leading to low photocatalytic activity. When the calcination temperature is increased to the range of 500-600℃, the carbon framework structure tends to be stable, which is also conducive to the effective doping and uniform distribution of samarium, thereby improving the near-infrared light response and carrier separation efficiency of the material, making the material exhibit better photocatalytic performance. However, when the calcination temperature is above 600℃, the excessively high temperature may cause the carbon quantum dots to undergo excessive graphitization or agglomeration, reducing the number of active sites, and may also cause pore structure shrinkage or even partial collapse, thereby reducing the specific surface area and photocatalytic activity.

[0022] Preferably, the alkaline solution in step S4 is a sodium hydroxide or potassium hydroxide solution; the concentration of the alkaline solution is 2-5M, and the etching time is 48-72h.

[0023] When the alkali concentration is below 2 M or the etching time is less than 48 h, the template is not completely removed, and the residual structure will affect the material's pore connectivity and specific surface area, which is not conducive to the mass transfer of reactants and the photocatalytic reaction. When the alkali concentration is above 5 M or the etching time exceeds 72 h, the excessively alkaline conditions can easily lead to excessive corrosion or collapse of the framework structure, thereby destroying the three-dimensional ordered porous structure and reducing the material's structural stability and photocatalytic performance.

[0024] Thirdly, this invention seeks to protect the application of the above-mentioned samarium-doped carbon quantum dot-based inverse opal material in the photocatalytic degradation of organic pollutants, wherein the samarium-doped carbon quantum dot-based inverse opal material can catalytically degrade organic pollutants under near-infrared light irradiation.

[0025] Preferably, the pH range of the reaction system for photocatalytic degradation of organic pollutants is 5 to 11, and the organic pollutants include tetracycline.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses carbon quantum dots as building blocks and silicon dioxide photonic crystals as templates. By introducing samarium and combining it with calcination and etching processes, carbon quantum dots self-construct to form a three-dimensional inverse opal structure. The material prepared by this invention fully utilizes the structural advantages of carbon quantum dots' high surface active site density and multi-coordination environment, which is conducive to the introduction and dispersion of rare earth samarium in the material. This results in uniform samarium distribution and controllable doping levels, thereby improving the utilization efficiency of coordination species. Using the carbon quantum dot-based inverse opal structure as a carrier, the inverse opal structure enhances the multiple scattering and localized light field effect within the material, which is beneficial for enhancing light-harvesting ability and promoting contact between reactants and active sites, significantly expanding the material's response to near-infrared light. Under near-infrared light irradiation conditions, this material exhibits excellent degradation performance for antibiotic-like organic pollutants, demonstrating highly efficient photocatalytic properties.

[0027] The samarium-doped carbon quantum dot-based inverse opal material provided by this invention can effectively respond to near-infrared light irradiation, breaking through the limitations of traditional photocatalytic materials that mainly rely on ultraviolet or visible light, and improving the utilization efficiency of low-energy light. Under near-infrared light conditions, this material can significantly promote the degradation of antibiotic-like organic pollutants, and is especially suitable for structurally stable and difficult-to-remove antibiotic pollutants.

[0028] The present invention provides a method for preparing samarium-doped carbon quantum dot-based inverse opal materials using economical and readily available raw materials, with a simple process and promising prospects for practical applications. Attached Figure Description

[0029] Figure 1 Here is a FETEM image of the Sm-CDs IO in Example 1; Figure 2 The corresponding elemental diagram of C, N, O, and Sm in the Sm-CDs IO sample of Example 1; Figure 3 The XRD patterns are for Example 1 (Sm-CDs IO), Comparative Example 1 (CDs IO), and Comparative Example 3 (CDs); Figure 4 The FTIR plots are for Example 1 (Sm-CDs IO), Comparative Example 1 (CDs IO), and Comparative Example 3 (CDs). Figure 5 Raman plots for Example 1 (Sm-CDs IO), Comparative Example 1 (CDs IO), and Comparative Example 3 (CDs); Figure 6 The UV-Vis-NIR diffuse reflectance spectra of Example 1 (Sm-CDs IO), Comparative Example 1 (CDs IO), and Comparative Example 3 (CDs) are shown. Figure 7 The photoluminescence spectra of Example 1 (Sm-CDs IO), Comparative Example 1 (CDs IO), and Comparative Example 3 (CDs) are shown. Figure 8 The degradation diagrams of tetracycline by the catalysts of Examples 1 and Comparative Examples 1-3 under near-infrared light (>800nm) irradiation are shown. Figure 9 Degradation of tetracycline by Sm-CDs IO under visible light (VIS), near-infrared light (>800nm, NIR), and sunlight (UV+Vis+NIR) irradiation. Figure 10 The degradation of tetracycline by Sm-CDs IO under different pH conditions is shown in the graph. Figure 11 The degradation of tetracycline by catalysts with different samarium doping amounts under near-infrared light (>800 nm) irradiation. Detailed Implementation

[0030] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Unless otherwise specified, the experimental methods used in the embodiments are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available. Example 1

[0031] This embodiment provides a samarium-doped carbon quantum dot-based inverse opal material (Sm-CDs IO), the preparation method of which includes the following steps: S1: Synthesis of silicon dioxide photonic crystal (SiO2) 74 mL of anhydrous ethanol, 10 mL of deionized water, 3 mL of ammonia, and 6 mL of tetraethyl silicate were added sequentially to a container. After stirring for 6 hours, the silica microspheres were encapsulated into colloidal crystals by centrifugation and dried to obtain a silica photonic crystal template, denoted as SiO2.

[0032] S2: Synthesis of carbon quantum dots 25 mmol of citric acid was dissolved in 50 mL of deionized water, and then 25 mmol of ethylenediamine was added. After stirring evenly, the mixture was transferred to an autoclave and hydrothermally heated at 200 °C for 5 h. The resulting product was concentrated using a vacuum rotary evaporator and then freeze-dried to obtain carbon quantum dot solid powder.

[0033] S3: Synthesis of Samarium-Doped Carbon Quantum Dots 1 g of carbon quantum dot solid powder was dissolved in 50 mL of deionized water, and then 0.33 g of samarium chloride was added. The mixture was stirred continuously until the solution became clear, and then transferred to an autoclave. The autoclave was hydrothermally heated at 200 °C for 8 h. The product was concentrated using a vacuum rotary evaporator and then freeze-dried to obtain samarium-doped carbon quantum dot solid powder.

[0034] S4: Synthesis of Samarium-Doped Carbon Quantum Dot-Based Inverse Opal (Sm-CDs IO) 1 g of samarium-doped carbon quantum dot solid powder was ground and mixed evenly with 0.2 g of SiO2 prepared in step S1. The mixture was then heat-treated to 600 °C for 3 h under argon protection at a heating rate of 5 °C / min to obtain the heat-treated product. This product was then ground into a uniform powder and etched with 2 M sodium hydroxide etching solution for 72 h. After etching, the sample was filtered, washed, and dried to obtain a carbon material with a three-dimensional macroporous structure, namely samarium-doped carbon quantum dot-based inverse opal material, named Sm-CDs IO, with a samarium doping content of 25 wt%. Comparative Example 1

[0035] The only difference between this comparative example and Example 1 is that the material prepared in this comparative example is undoped with samarium to obtain undoped carbon quantum dot-based inverse opal (CDs IO), and its preparation method includes the following steps: S1: Synthesis of silicon dioxide photonic crystal (SiO2) 74 mL of anhydrous ethanol, 10 mL of deionized water, 3 mL of ammonia, and 6 mL of tetraethyl silicate were added sequentially to a container. After stirring for 6 hours, the silica microspheres were encapsulated into colloidal crystals by centrifugation and dried to obtain a silica photonic crystal template, denoted as SiO2.

[0036] S2: Synthesis of carbon quantum dots (CDs) 25 mmol of citric acid was dissolved in 50 mL of deionized water, and then 25 mmol of ethylenediamine was added. After stirring evenly, the mixture was transferred to an autoclave and hydrothermally heated at 200 °C for 5 h. The resulting product was concentrated using a vacuum rotary evaporator and then freeze-dried to obtain carbon quantum dot solid powder. S3: Synthesis of carbon quantum dot-based inverse opal (CDs IO) 1g of carbon quantum dot solid powder was ground and mixed evenly with 0.2g of SiO2 prepared in step S1. The mixture was then heat-treated to 600℃ for 3 h under argon protection at a heating rate of 5℃ / min to obtain the heat-treated product. This product was then ground into a uniform powder and etched with 2M sodium hydroxide etching solution for 72 h. After etching, the sample was filtered, washed, and dried to obtain a carbon material with a three-dimensional macroporous structure, named CDs IO. Comparative Example 2

[0037] The difference between this comparative example and Example 1 is that the material prepared in this comparative example did not use a silicon dioxide photonic crystal template and was not etched with sodium hydroxide. The material prepared in this comparative example is samarium-doped carbon quantum dots (Sm-CDs), and the preparation method includes the following steps: 25 mmol of citric acid was dissolved in 50 mL of deionized water, and then 25 mmol of ethylenediamine was added. After stirring evenly, the mixture was transferred to an autoclave and hydrothermally heated at 200 °C for 5 h. The resulting product was concentrated using a vacuum rotary evaporator and then freeze-dried to obtain carbon quantum dot solid powder.

[0038] 1 g of carbon quantum dot solid powder was dissolved in 50 mL of deionized water, and then 0.33 g of samarium chloride was added. The mixture was stirred continuously until the solution became clear, and then transferred to an autoclave. The autoclave was hydrothermally heated at 200 °C for 8 h. The product was concentrated using a vacuum rotary evaporator and then freeze-dried to obtain samarium-doped carbon quantum dot solid powder.

[0039] 1g of solid powder samarium-doped carbon quantum dots was heat-treated to 600℃ for 3 h under argon protection at a heating rate of 5℃ / min to obtain the heat-treated product. The product was then ground into a uniform powder and named Sm-CDs. Comparative Example 3

[0040] The difference between this comparative example and Example 1 is that this comparative example did not use a silicon dioxide photonic crystal template, did not undergo samarium doping, and was not etched with sodium hydroxide. The product prepared in this comparative example is undoped carbon quantum dots (CDs). The specific preparation method includes the following steps: 25 mmol of citric acid was dissolved in 50 mL of deionized water, and then 25 mmol of ethylenediamine was added. The mixture was then transferred to an autoclave and hydrothermally heated at 200 °C for 5 h. The resulting product was concentrated using a vacuum rotary evaporator and then freeze-dried to obtain solid carbon quantum dots.

[0041] 1g of solid carbon quantum dots powder was heat-treated to 600℃ for 3h under argon protection at a heating rate of 5℃ / min to obtain the heat-treated product. The heat-treated product was then ground into a uniform powder and named CDs. Performance Characterization

[0042] Example 1 (Sm-CDs IO) Sample in-field emission transmission electron microscopy (FETEM) as follows Figure 1 As shown, the elemental distribution of C, N, O, and Sm in the sample is as follows: Figure 2 As shown in the FETEM images, the obtained material exhibits a regular three-dimensional porous structure with a relatively uniform pore size distribution, ranging from 300 to 350 nm, indicating the successful construction of the inverse opal structure. Further energy dispersive spectroscopy (EDS) results show that C, N, O, and Sm elements are uniformly distributed in the material, indicating that samarium was successfully introduced into the carbon quantum dot-based inverse opal structure without significant agglomeration.

[0043] The X-ray diffraction (XRD) patterns of the samples from Example 1 (Sm-CDs IO), Comparative Example 1 (CDs IO), and Comparative Example 3 (CDs) are as follows: Figure 3 As shown in the figure, the CDs sample exhibits typical broad and diffuse peaks, indicating its amorphous or low crystallinity characteristics. Neither the CDs IO nor the Sm-CDs IO samples showed obvious impurity phase diffraction peaks, indicating that the material structure remained stable during calcination and etching. The overall XRD patterns before and after samarium doping showed little change, indicating that samarium doping did not damage the main structure of the material.

[0044] The FTIR spectra of the samples from Example 1 (Sm-CDs IO), Comparative Example 1 (CDs IO), and Comparative Example 3 (CDs) are shown below. Figure 4 As shown, characteristic absorption peaks related to hydroxyl, amino, and carboxyl groups can be observed in the CDs samples, indicating that the carbon quantum dot surface contains abundant oxygen- and nitrogen-containing functional groups. After etching, the peak intensities of some functional groups in CDs IO and Sm-CDs IO change, but the materials still retain a certain number of surface functional groups, which is beneficial to their dispersion and reaction in the aqueous system.

[0045] Raman plots of the samples from Example 1 (Sm-CDs IO), Comparative Example 1 (CDs IO), and Comparative Example 3 (CDs) are shown below. Figure 5 As shown. Each sample is located at approximately 1350 cm. -1and 1580 cm -1 The D and G peaks appear at the location, corresponding to the defect structure and graphitized carbon structure in the carbon material, respectively.

[0046] The UV-Vis-NIR diffuse reflectance spectra of the samples from Example 1 (Sm-CDs IO), Comparative Example 1 (CDs IO), and Comparative Example 3 (CDs) are shown below. Figure 6 As shown in the figure, Sm-CDs IO exhibits significant absorption enhancement in the near-infrared region, indicating that the introduction of samarium doping and the inverse opal structure helps to extend the optical response range of the material.

[0047] The photoluminescence spectra of the samples from Example 1 (Sm-CDs IO), Comparative Example 1 (CDs IO), and Comparative Example 3 (CDs) are as follows: Figure 7 As shown, the photoluminescence intensity of Sm-CDs IO changes significantly compared to CDs and CDs IO, indicating that samarium doping and structural modulation affect the photogenerated carrier behavior of the material. Photocatalytic degradation performance test

[0048] The method for evaluating the photocatalytic degradation activity of antibiotics provided by this invention is as follows: In the degradation experiments, all reactions were carried out in a 120 mL quartz glass tube with a diameter of 3.0 cm and a height of 20 cm. The light source was a 300 W xenon lamp with a wavelength cutoff filter (800 nm). A 20 mg / L tetracycline solution was used as the pollutant to investigate the photocatalytic degradation performance of samarium-doped carbon quantum dot-based inverse opal. For a typical photocatalytic process, 20 mg of catalyst was added to 50 mL of a 20 mg / L tetracycline solution, and the solution was stirred with a strong magnetic stirrer for 1 h to establish adsorption-desorption equilibrium. Based on this, near-infrared light irradiation was introduced to carry out the photocatalytic reaction. During the reaction, 1 mL of solution was taken at specified time intervals and filtered using a syringe with a 0.22 μm filter tip.

[0049] High-performance liquid chromatography (HPLC, Shimadzu 2030C) was used to monitor the concentration of pollutants during the degradation process. The mobile phase was a mixture of 20% acetonitrile and 80% 0.2% formic acid aqueous solution, and the flow rate was 1.0 mL / min. The detection wavelength was 355 nm, and the injection volume was 10 μL.

[0050] The degradation diagrams of tetracycline by Example 1 (Sm-CDs IO), Comparative Example 1 (CDs IO), Comparative Example 2 (Sm-CDs), and Comparative Example 3 (CDs) as catalysts under near-infrared light (>800nm) irradiation are shown below. Figure 8As shown in the figure, under the same experimental conditions, the degradation efficiency of Sm-CDs IO for tetracycline was significantly higher than that of CDs, Sm-CDs, and CDs IO, indicating that the synergistic effect of samarium doping and the inverse opal structure is beneficial to improving the degradation performance of the material under near-infrared light conditions.

[0051] Furthermore, using the Sm-CDs IO prepared in Example 1 as a catalyst, the degradation curves of tetracycline under visible light (Vis), near-infrared light (NIR), and sunlight (UV+Vis+NIR) irradiation are shown below. Figure 9 As shown in the figure. The results indicate that Sm-CDs IO exhibits certain degradation capabilities under different light source conditions, especially under near-infrared light and sunlight irradiation conditions, demonstrating good degradation performance and indicating that the material has good near-infrared light response adaptability.

[0052] Further analysis of the degradation of tetracycline by Sm-CDs IO under different pH conditions in the catalytic tetracycline degradation reaction system yielded the following results: Figure 10 As shown in the figure. Experimental results show that tetracycline can be efficiently degraded within a wide pH range of 5 to 11, demonstrating its applicability under different aquatic environmental conditions. Example 2

[0053] The purpose of this embodiment is to analyze the effect of samarium doping amount on the photocatalytic degradation of tetracycline in samarium-doped carbon quantum dot-based inverse opal materials.

[0054] Referring to the preparation method of samarium-doped carbon quantum dot-based inverse opal material in Example 1, the amount of samarium chloride added in step S3 was adjusted to 0.11g, 0.33g, and 0.66g respectively, to obtain samarium-doped carbon quantum dot-based inverse opal materials with samarium doping amounts of 10wt%, 25wt%, and 40wt%, respectively, which are denoted as 10%Sm-CDs 10, 25%Sm-CDs 10, and 40%Sm-CDs 10.

[0055] Using 10% Sm-CDs IO, 25% Sm-CDs IO, and 40% Sm-CDs IO as catalysts, respectively, and following the experimental method described above for the catalytic degradation of tetracycline, the degradation patterns of tetracycline under near-infrared light (>800 nm) irradiation with different samarium doping amounts were obtained as shown in the figure. Figure 11As shown in the figure, the results indicate that the degradation efficiency of the material for tetracycline first increases and then decreases with increasing samarium doping concentration. At a low doping concentration of 10 wt%, the insufficient introduction of samarium limits the improvement in the material's near-infrared light response, resulting in low photocatalytic activity. When the doping concentration increases to a moderate level of 25 wt%, the material's near-infrared light absorption and carrier separation efficiency are significantly enhanced, thus exhibiting optimal catalytic degradation performance. However, when the doping concentration is further increased to 40 wt%, excess samarium may introduce defects or form recombination centers, leading to intensified recombination of photogenerated carriers and consequently reducing photocatalytic activity. Therefore, the suitable samarium doping concentration range is 15 wt%–30 wt%, preferably 25 wt%, within which the material exhibits superior near-infrared photocatalytic degradation performance.

Claims

1. A samarium-doped carbon quantum dot-based inverse opal material, characterized in that, The material is formed by calcination and etching using samarium-doped carbon quantum dots as building blocks and silicon dioxide photonic crystals as templates. The samarium-doped carbon quantum dot-based inverse opal material has a three-dimensional porous structure with a pore size of 300–350 nm; the samarium doping content in the material is 10–40 wt%; the material has near-infrared light response performance and exhibits broad-spectrum absorption characteristics in the 200–1400 nm wavelength range.

2. A method for preparing the samarium-doped carbon quantum dot-based inverse opal material as described in claim 1, characterized in that, Includes the following steps: S1: Synthesis of silicon dioxide photonic crystal template Using tetraethyl silicate as a precursor, a hydrolysis-condensation reaction is carried out under the action of a weak alkaline catalyst to form a sol, which is then centrifuged, encapsulated into colloidal crystals, and dried to obtain a silica photonic crystal template. S2: Synthesis of carbon quantum dot powder Citric acid and ethylenediamine were reacted hydrothermally, and the resulting product was concentrated and dried to obtain carbon quantum dot powder. S3: Synthesis of Samarium-Doped Carbon Quantum Dots Samarium source was subjected to hydrothermal reaction with carbon quantum dot powder, and the resulting product was concentrated and dried to obtain samarium-doped carbon quantum dot powder. S4: Synthesis of Samarium-doped carbon quantum dot-based inverse opal After mixing the samarium-doped carbon quantum dot powder in step S3 with the silicon dioxide photonic crystal template in step S1, the mixture is calcined. The calcined product is then subjected to alkaline etching to obtain samarium-doped carbon quantum dot-based inverse opal material.

3. The method for preparing samarium-doped carbon quantum dot-based inverse opal materials as described in claim 2, characterized in that, The molar ratio of citric acid to ethylenediamine is 0.8 to 1.2:

1.

4. The method for preparing samarium-doped carbon quantum dot-based inverse opal materials as described in claim 2, characterized in that, The hydrothermal reaction conditions in step S2 are: 180℃~200℃ for 5~8h; the hydrothermal reaction conditions in step S3 are: 180℃~200℃ for 8~10h.

5. The method for preparing samarium-doped carbon quantum dot-based inverse opal material as described in claim 2, characterized in that, The samarium source is a soluble trivalent samarium salt; the mass ratio of the carbon quantum dot powder to the samarium source is 1 to 9:

1.

6. The method for preparing samarium-doped carbon quantum dot-based inverse opal materials as described in claim 2, characterized in that, The mass ratio of the samarium-doped carbon quantum dot powder to the silicon dioxide photonic crystal template is 4-5:

1.

7. The method for preparing samarium-doped carbon quantum dot-based inverse opal material as described in claim 2, characterized in that, The calcination parameters in step S4 are: heating to 500-600°C at a heating rate of 5-10°C / min, and calcining at this temperature in an inert atmosphere for 3-4 hours.

8. The method for preparing samarium-doped carbon quantum dot-based inverse opal materials as described in claim 2, characterized in that, The alkaline solution mentioned in step S4 is a sodium hydroxide or potassium hydroxide solution; the concentration of the alkaline solution is 2-5M, and the etching time is 48-72h.

9. The application of the samarium-doped carbon quantum dot-based inverse opal material according to claim 1 in the photocatalytic degradation of organic pollutants, characterized in that, The samarium-doped carbon quantum dot-based inverse opal material can catalytically degrade organic pollutants under near-infrared light irradiation.

10. The application as described in claim 9, characterized in that, The reaction system for photocatalytic degradation of organic pollutants has a pH range of 5 to 11, and the organic pollutants include tetracycline.

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