A broad-spectrum, high-efficiency visible light photocatalyst, CeO2 / cGO, its preparation method and its application in water purification.

Abstract

This invention discloses a broad-spectrum and highly efficient visible light catalyst CeO2 / cGO, its preparation method, and its application in water purification. It relates to the fields of nanocomposite material preparation and environmental photocatalysis, and includes the following steps: ultrasonically dispersing graphene oxide (GO) in deionized water, adding hydrogen peroxide, reacting at 60-65℃ for at least 24 hours, and centrifuging and washing to obtain carboxyl-rich graphene oxide (cGO); dispersing cGO in deionized water, adding N,N-dimethylformamide (DMF) and cerium salt, refluxing at 130-132℃ for 5-6 hours, and obtaining CeO2 / cGO nanocomposite material through centrifugation, washing, and drying. This invention prepares carboxyl-rich graphene oxide (cGO) through deep oxidation with hydrogen peroxide, and then constructs CeO2 / cGO nanocomposite material through heating and reflux, achieving ultra-fast, broad-spectrum, stable, and efficient degradation of organic pollutants in water, including organic dyes, antibiotics, phenolic endocrine disruptors, and algal toxins, under natural light.

Description

Technical Field

[0001] This invention relates to the fields of nanocomposite material preparation and environmental photocatalysis, specifically to a broad-spectrum, high-efficiency visible light catalyst CeO2 / cGO, its preparation method, and its application in water purification. Background Technology

[0002] With the rapid advancement of industrialization and urbanization, the continuous accumulation of emerging organic pollutants in water bodies has posed a serious threat to ecological environment security and human health. Among these, organic dyes such as methylene blue (MB) and rhodamine B (RhB), antibiotics such as norfloxacin (NOR) and tetracycline (TC), phenolic endocrine disruptors such as bisphenol A (BPA), and algal toxins such as microcystin-LR (MC-LR) have become key and challenging areas for water pollution control due to their persistence, bioaccumulation, high toxicity, and recalcitrant degradation characteristics. These pollutants are widely present in surface water, groundwater, and industrial wastewater. Conventional water treatment processes (coagulation, sedimentation, filtration, disinfection, etc.) are insufficient for their efficient removal, while technologies such as biodegradation and chemical oxidation generally suffer from low degradation efficiency, high treatment costs, and the potential for secondary pollution.

[0003] Photocatalysis, as a green and advanced oxidation technology, utilizes solar energy to drive catalysts to generate highly reactive oxidizing species, completely mineralizing organic pollutants into harmless small molecules such as carbon dioxide and water. It boasts advantages such as high efficiency, environmental friendliness, and no secondary pollution, demonstrating enormous application potential in water pollution control. Currently, traditional metal oxide photocatalysts such as titanium dioxide (TiO2) and zinc oxide (ZnO) suffer from core problems including easy recombination of photogenerated electron-hole pairs, low quantum efficiency, wide band gaps, and responsiveness only to ultraviolet light (accounting for only 4%-5% of the solar spectrum), making it difficult to achieve efficient catalysis under natural light conditions.

[0004] Cerium oxide (CeO2) is rich in oxygen vacancy defects and has reversible CeO2. 3+ / Ce 4+Redox pairs possess excellent oxygen storage and release capabilities and redox activity, which are beneficial for photogenerated charge separation and the generation of active species, making them highly promising photocatalytic materials. However, single CeO2 still suffers from problems such as easy recombination of photogenerated charge carriers and insufficient visible light utilization, limiting its practical applications. Graphene oxide (GO), as a two-dimensional carbon material, has an ultra-large specific surface area, excellent electron conductivity, and abundant oxygen-containing functional groups on its surface, making it an ideal carrier for photocatalytic composite materials. It can rapidly capture and transport photogenerated electrons, suppress charge carrier recombination, and enhance the adsorption and enrichment of organic pollutants through π-π conjugation. However, the density of carboxyl functional groups on the surface of ordinary GO is limited, and the interfacial coupling with metal oxides is weak, which cannot provide sufficient anchoring sites for nanoparticles, easily leading to nanoparticle aggregation. Furthermore, the cycling stability and interfacial charge transport efficiency of the composite material still need to be improved.

[0005] In existing research, although ZnO / carboxylated graphene oxide composite materials can achieve rapid degradation of organic pollutants, the degradation efficiency drops to 87% after five cycles, indicating insufficient long-term stability. Therefore, developing a broad-spectrum photocatalytic material with simple preparation process, strong visible light response, high catalytic efficiency, good cycle stability, and wide environmental adaptability has become an urgent need in the field of water organic pollutant treatment. Summary of the Invention

[0006] The purpose of this invention is to provide a broad-spectrum and highly efficient visible light photocatalyst CeO2 / cGO, its preparation method, and its application in water purification, so as to solve the problems of low visible light utilization, slow degradation rate, insufficient cycle stability, and insufficient environmental adaptability of existing photocatalysts.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] According to the first aspect of this disclosure, a method for preparing a broad-spectrum, high-efficiency visible light photocatalyst CeO2 / cGO nanocomposite material is proposed, comprising the following steps:

[0009] S1. Graphene oxide (GO) was ultrasonically dispersed in deionized water at room temperature, hydrogen peroxide was added, and the mixture was stirred at 60-65°C for no less than 24 hours. After the reaction was completed, the mixture was centrifuged and washed to obtain carboxyl-rich graphene oxide (cGO).

[0010] S2. The obtained carboxyl-rich graphene oxide (cGO) was dispersed in deionized water, and N,N-dimethylformamide (DMF) and cerium salt were added. The mixture was refluxed at 130-132°C for 5-6 hours. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain CeO2 / cGO nanocomposite material.

[0011] Furthermore, in step S2, the cerium salt is any one or a combination of cerium nitrate, cerium chloride, and cerium sulfate.

[0012] Further, in step S2, the ratio of the amount of cerium salt, deionized water and N,N-dimethylformamide is 2g:20-30mL:200-300mL.

[0013] According to a second aspect of this disclosure, a broad-spectrum, high-efficiency visible light catalyst CeO2 / cGO nanocomposite material prepared by the preparation method of the first aspect is proposed.

[0014] Furthermore, the composite material uses carboxyl-rich graphene oxide (cGO) as a carrier, and the surface of the cGO is uniformly loaded with nano-CeO2 particles with a particle size of 5-15 nm. The nano-CeO2 particles and cGO form a Ce-OC interface chemical bond, and the optical band gap of the composite material is 1.66 eV.

[0015] According to the third aspect of this disclosure, the application of the nanocomposite material of the second aspect in degrading organic pollutants in water under natural or visible light conditions is proposed.

[0016] Furthermore, the organic pollutants include any one or more combinations of organic dyes, antibiotics, phenolic endocrine disruptors, and algal toxins;

[0017] The organic dye is methylene blue (MB) or rhodamine B (RhB); the antibiotic is norfloxacin (NOR) or tetracycline (TC); the phenolic endocrine disruptor is bisphenol A (BPA); and the algal toxin is microcystin-LR (MC-LR).

[0018] Furthermore, under natural light irradiation, the CeO2 / cGO nanocomposite material exhibits a degradation rate of over 99% for MB, RhB, NOR, TC, and MC-LR within 1 minute, and a degradation rate of over 90% for BPA within 1 minute.

[0019] Furthermore, the water body refers to an aquatic environment with a pH value of 2-12, as well as natural aquatic environments such as tap water, pond water, and river water.

[0020] Furthermore, the CeO2 / cGO nanocomposite material maintains stable degradation performance against all target organic pollutants; and after being recycled 18 times, the degradation efficiency of the CeO2 / cGO nanocomposite material for MB is still higher than 95%.

[0021] Compared with existing technologies, the present invention provides a broad-spectrum and highly efficient visible light photocatalyst CeO2 / cGO, its preparation method, and its application in water purification. The target composite material can be obtained through only two steps: hydrogen peroxide oxidation and heating reflux. The reaction conditions are mild, and the reaction medium DMF can be recycled and reused, significantly reducing the preparation cost. It is green and environmentally friendly and suitable for large-scale production. The carboxyl-rich cGO support obtained by deep oxidation not only achieves uniform loading of 5-15nm CeO2 nanoparticles and avoids agglomeration, but also forms a strong Ce-OC interface bond with CeO2, constructing an efficient charge separation and transfer channel, which greatly improves the photocatalytic quantum efficiency. The composite material has a narrow band gap of 1.66eV, exhibits strong and wide-range light absorption in the visible light region, and can maintain efficient degradation ability in complex natural water environments. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0023] Figure 1 The images show the morphology and structure of the CeO2 / cGO nanocomposite material; where A is a transmission electron microscope (TEM) image and B is a high-resolution transmission electron microscope (HRTEM) image.

[0024] Figure 2 The graphs show the degradation effects of CeO2 / cGO nanocomposites on various organic pollutants. In the graphs, A is the UV-Vis absorption spectrum of MB degradation, B is the effect of degradation time on MB degradation efficiency, C is the effect of catalyst concentration on MB degradation efficiency, and D is the degradation efficiency of MB, RhB, MB / RhB mixed system, NOR, TC, NOR / TC mixed system, BPA, and MC-LR.

[0025] Figure 3 The graphs show the stability and anti-interference ability of CeO2 / cGO nanocomposites; where A represents the effect of pH value on MB degradation efficiency, B represents the effect of the number of cycles on MB degradation efficiency, and C represents the effect of free radical scavengers on MB degradation efficiency.

[0026] Figure 4 The image shows the band gap analysis of CeO2 / cGO nanocomposites; where AC represents the band gap fitting analysis of GO, cGO, and CeO2 / cGO, respectively. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0028] The reagents and instruments used in the specific embodiments of this invention are as follows:

[0029] Reagents: Graphene oxide (GO) was prepared using a modified Hummers method; methylene blue (MB), rhodamine B (RhB), norfloxacin (NOR), tetracycline (TC), bisphenol A (BPA), cerium nitrate, N,N-dimethylformamide (DMF), and hydrogen peroxide (30%) were all purchased from Aladdin Reagent Co., Ltd.; microcystin-LR (MC-LR) was purchased from Beijing Yipulis Technology Development Co., Ltd.; all other reagents were commercially available analytical grade, and the experimental water was deionized water.

[0030] Instruments: CNC ultrasonic cleaner, constant temperature magnetic stirrer, high-speed centrifuge, vacuum drying oven, ultraviolet-visible spectrophotometer, transmission electron microscope (TEM), X-ray photoelectron spectrometer (XPS), ultraviolet-visible diffuse reflectance spectrometer, electron paramagnetic resonance spectrometer (EPR).

[0031] Example 1:

[0032] This embodiment prepares CeO2 / cGO nanocomposite materials according to the method described in this invention. The specific steps are as follows:

[0033] S1. Preparation of carboxyl-rich graphene oxide (cGO): Weigh 500 mg of graphene oxide (GO), add 25 mL of deionized water, and ultrasonically disperse at room temperature for 45 min to obtain a uniform GO dispersion; add 350 mL of 30% hydrogen peroxide to the dispersion, stir evenly, and place in a 62℃ constant temperature water bath, stirring at 650 rpm for 28 h; after the reaction is complete, centrifuge the reaction solution at 11000 rpm for 10 min, collect the solid product, wash it three times with deionized water to obtain black viscous carboxyl-rich graphene oxide (cGO).

[0034] Preparation of CeO2 / cGO nanocomposite material S2: All cGO obtained in step S1 was dispersed in 25 mL of deionized water and ultrasonically dispersed for 30 min to obtain a uniform cGO dispersion; 250 mL of DMF and 2 g of cerium nitrate were added to the dispersion in sequence, stirred evenly, heated to 131 °C, and refluxed at a constant temperature for 5.5 h with a stirring speed of 650 rpm; after the reaction was completed, the mixture was naturally cooled to room temperature, centrifuged at 9000 rpm for 8 min, the solid product was collected, washed 4 times with deionized water, and dried in a vacuum drying oven at 58 °C for 12 h to obtain CeO2 / cGO nanocomposite material.

[0035] Example 2:

[0036] This embodiment is used to understand the structural and optical properties characterization of CeO2 / cGO nanocomposites.

[0037] 1. Morphological and microstructural characterization

[0038] The morphology of the CeO2 / cGO nanocomposite material prepared in Example 1 was characterized by transmission electron microscopy, and the results are as follows: Figure 1 As shown. From Figure 1 TEM images of cGO show that it exhibits a typical two-dimensional layered structure, with a large number of CeO2 nanoparticles uniformly loaded on the surface of the cGO sheets, without obvious aggregation. Figure 1 The HRTEM image of B shows that the particle size of CeO2 nanoparticles is concentrated in the range of 5-15 nm, and the lattice spacing is 0.315 nm, corresponding to the (111) crystal plane of cubic fluorite CeO2.

[0039] The interfacial chemical bonding of the composite material was characterized by X-ray photoelectron spectroscopy. The results showed that characteristic peaks of Ce-OC bonds appeared in the C1s spectrum of the composite material, and characteristic peaks of lattice oxygen, surface adsorbed oxygen, and Ce-OC bonds appeared in the O1s spectrum. Ce3d spectra also showed characteristic peaks of Ce bonds. 3+ With Ce 4+ The characteristic peaks confirmed that a strong Ce-OC interfacial chemical bond was formed between CeO2 and cGO, and that the composite material contained abundant oxygen vacancy defects, providing sufficient active sites for the photocatalytic reaction.

[0040] 2. Optical performance and bandgap analysis

[0041] The optical properties of GO, cGO, and CeO2 / cGO from Example 1 were tested using a UV-Vis diffuse reflectance spectrometer. The UV-Vis DRS spectra showed that GO had characteristic absorption peaks at 230 nm and 300 nm, while the characteristic absorption peaks of cGO were weakened. CeO2 / cGO, on the other hand, showed strong and broad absorption in the visible light region of 300-700 nm, indicating that its visible light trapping ability was greatly enhanced.

[0042] The results were obtained through bandgap fitting calculations, as shown below. Figure 4 As shown, the band gap of GO is 2.71 eV, the band gap of cGO is 3.51 eV, while the band gap of the CeO2 / cGO nanocomposite material of the present invention is significantly reduced to 1.66 eV, which greatly broadens the visible light response range and lays the foundation for efficient photocatalytic reactions under natural light.

[0043] 3. Characterization of bioactive species generation

[0044] Electron paramagnetic resonance spectroscopy, combined with spin trapping technology, was used to detect the active species generated by the CeO2 / cGO nanocomposite material of Example 1 under natural light irradiation. The test results showed that under natural light irradiation, the composite material can rapidly generate hydroxyl radicals (・OH) and superoxide radicals (・O2). - Multiple reactive oxygen species, including singlet oxygen (¹O2), were detected, and the signal intensity of these reactive species continuously increased with prolonged irradiation time; simultaneously, photogenerated electrons (e- ... - ) and holes (h + The characteristic signals confirmed that the composite material can achieve efficient photogenerated charge separation, providing sufficient highly oxidizing active species for the degradation of organic pollutants.

[0045] Example 3:

[0046] In this embodiment, the CeO2 / cGO nanocomposite material prepared in Example 1 was used as a photocatalyst, and MB, RhB, NOR, TC, BPA, and MC-LR were used as target pollutants to test its photocatalytic degradation performance. The specific test methods and results are as follows:

[0047] 1. Preparation of pollutant stock solution and catalyst dispersion

[0048] 1 mg / mL catalyst dispersion: Accurately weigh 100 mg of CeO2 / cGO nanocomposite material, add 100 mL of deionized water, and ultrasonically disperse for 10 min to obtain a uniform 1 mg / mL catalyst dispersion. Store in the dark for later use.

[0049] 1 mg / mL MB stock solution: Accurately weigh 50 mg of MB solid powder, dissolve it in deionized water, and dilute to 50 mL. Store in the dark for later use.

[0050] 1 mg / mL RhB stock solution: Accurately weigh 50 mg of RhB solid powder, dissolve it in deionized water, and bring the volume to 50 mL. Store in the dark for later use.

[0051] 1 mg / mL NOR stock solution: Accurately weigh 50 mg of NOR solid powder, dissolve it in 0.1 mol / L NaOH solution, and dilute to 50 mL. Store in the dark for later use.

[0052] 1 mg / mL TC stock solution: Accurately weigh 50 mg of TC solid powder, dissolve it in deionized water, adjust the pH to 3 with dilute HCl, and bring the volume to 50 mL. Store in the dark for later use.

[0053] 1 mg / mL BPA stock solution: Accurately weigh 50 mg of BPA solid powder, dissolve it in anhydrous ethanol, and dilute to 50 mL. Store in the dark for later use.

[0054] 1 mg / mL MC-LR stock solution: Accurately weigh 2.5 mg MC-LR solid, dissolve it in 1 mL of anhydrous ethanol, add 1.5 mL of deionized water, mix well, and store in the dark under cold conditions for later use.

[0055] 2. Photocatalytic degradation test of single-component organic pollutants

[0056] Take the above-mentioned pollutant stock solutions, add deionized water and catalyst dispersion to prepare 2 mL reaction systems, irradiate with natural light for 1 min, centrifuge to separate the supernatant, and use a UV-Vis spectrophotometer to measure the intensity change of the characteristic absorption peaks of the pollutants to calculate the degradation rate. The specific experimental groups and results are as follows:

[0057] MB degradation system: Take 10 μL of 1 mg / mL MB stock solution, add 1.5 mL of deionized water and 0.5 mL of 1 mg / mL catalyst dispersion, mix well, and irradiate under natural light for 1 min. Results are as follows: Figure 2 As shown in Figure A, the characteristic absorption peak of MB completely disappeared, and the degradation rate reached 99.8%.

[0058] RhB degradation system: Take 60 μL of 1 mg / mL RhB stock solution, add 1.5 mL of deionized water and 0.5 mL of 1 mg / mL catalyst dispersion, mix well, and irradiate under natural light for 1 min. Results are as follows: Figure 2 As shown in Figure D, the characteristic absorption peak of RhB completely disappeared, and the degradation rate reached 99.6%.

[0059] NOR degradation system: Take 10 μL of 1 mg / mL NOR stock solution, add 1.5 mL of deionized water and 0.5 mL of 1 mg / mL catalyst dispersion, mix well, and irradiate under natural light for 1 min. Results are as follows: Figure 2 As shown in Figure D, the characteristic absorption peak of NOR completely disappeared, and the degradation rate reached 99.5%.

[0060] TC degradation system: Take 30 μL of 1 mg / mL TC stock solution, add 1.5 mL of deionized water and 0.5 mL of 1 mg / mL catalyst dispersion, mix well, and irradiate under natural light for 1 min. Results are as follows: Figure 2 As shown in Figure D, the characteristic absorption peak of TC completely disappeared, and the degradation rate reached 99.3%.

[0061] BPA degradation system: Take 100 μL of 1 mg / mL BPA stock solution, add 1.0 mL of deionized water and 1.0 mL of 1 mg / mL catalyst dispersion, mix well, and irradiate under natural light for 1 min. Results are as follows: Figure 2 As shown in Figure D, the characteristic absorption peak of BPA decreased significantly, and the degradation rate reached 92.7%.

[0062] MC-LR degradation system: Take 50 μL of 1 mg / mL MC-LR stock solution, add 1.5 mL of deionized water and 0.5 mL of 1 mg / mL catalyst dispersion, mix well, and irradiate under natural light for 1 min. Results are as follows: Figure 2 As shown in Figure D, the characteristic absorption peak of MC-LR completely disappeared, and the degradation rate reached 99.4%.

[0063] 3. Photocatalytic degradation test of mixed organic pollutants

[0064] MB / RhB mixed system: Take 10 μL of 1 mg / mL MB stock solution and 60 μL of 1 mg / mL RhB stock solution, add 1.5 mL of deionized water and 0.5 mL of 1 mg / mL catalyst dispersion, mix well, and irradiate under natural light for 1 min. Results are as follows: Figure 2 As shown in Figure D, the characteristic absorption peaks of both MB and RhB completely disappeared, and the degradation rates of both pollutants exceeded 99%.

[0065] NOR / TC mixed system: Take 10 μL of 1 mg / mL NOR stock solution and 30 μL of 1 mg / mL TC stock solution, add 1.5 mL of deionized water and 0.5 mL of 1 mg / mL catalyst dispersion, mix well, and irradiate under natural light for 1 min. Results are as follows: Figure 2 As shown in Figure D, the characteristic absorption peaks of both NOR and TC completely disappeared, and the degradation rates of both pollutants exceeded 99%.

[0066] The above results confirm that the composite material of the present invention can simultaneously and efficiently degrade multiple organic pollutants in a mixed system without selective inhibition, and possesses excellent broad-spectrum degradation performance.

[0067] 4. Effect of catalyst concentration on degradation performance

[0068] MB, NOR, BPA, and MC-LR were selected as target pollutants, with catalyst concentration gradients ranging from 0 to 1.0 mg / mL. Other reaction conditions remained consistent with the single-component degradation experiments described above, and degradation efficiency was tested within 1 minute. The results showed that the degradation rates of MB, NOR, and MC-LR increased rapidly with increasing catalyst concentration, exceeding 99% at a catalyst concentration of 0.15 mg / mL. The degradation rate of BPA reached over 90% at a catalyst concentration of 0.5 mg / mL, conforming to saturation kinetics. Therefore, the catalyst dosage can be adjusted according to the target pollutant type to achieve efficient degradation.

[0069] 5. Effect of degradation time on degradation performance

[0070] MB, NOR, BPA, and MC-LR were selected as target pollutants, respectively. Irradiation time gradients were set from 0 to 10 min, with other reaction conditions consistent with the single-component degradation experiments described above. Degradation efficiencies at different time points were tested. Results showed that the degradation rates of MB, NOR, and MC-LR exceeded 99% after 1 min of irradiation, while the degradation rate of BPA exceeded 90% after 1 min. The degradation curves then stabilized, confirming the ultrafast degradation kinetics of the material of this invention, enabling efficient removal of pollutants in a very short time.

[0071] Example 4:

[0072] This embodiment is used to test the environmental adaptability and stability of CeO2 / cGO nanocomposites.

[0073] 1. pH adaptability test

[0074] Using MB as the target pollutant, reaction systems with pH values ​​of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 were prepared. The remaining reaction conditions were consistent with those in the MB single-component degradation experiment. The degradation efficiency after 1 minute of natural light irradiation was tested, and the results are as follows: Figure 3 As shown in Figure A. The results show that the degradation rate of MB by the composite material remained above 99% within a wide pH range of 2-12, without significant fluctuations, confirming its excellent acid-base adaptability and allowing it to be directly applied to water treatment in different acid-base environments without adjusting the pH of the water.

[0075] 2. Adaptability testing to complex natural aquatic environments

[0076] Reaction systems containing MB, RhB, NOR, TC, BPA, and MC-LR were prepared using deionized water, tap water, pond water, and river water as reaction media, respectively. Other reaction conditions were consistent with those in the single-component degradation experiments. The degradation efficiency after 1 minute of natural light irradiation was tested. Results showed that in natural water bodies such as tap water, pond water, and river water, the composite material maintained a degradation rate of over 95% for all six target pollutants, with no significant difference compared to the deionized water system. This confirms that background matrices such as inorganic ions and natural organic matter in natural water bodies have no significant impact on its degradation performance, demonstrating excellent environmental resistance and making it directly applicable to the pollution control of actual natural water bodies.

[0077] 3. Stability test during repeated use

[0078] A continuous cyclic degradation experiment was conducted using MB as the target pollutant. After each degradation reaction, the composite material was recovered by centrifugation, washed three times with deionized water, vacuum dried, and reused in the next degradation experiment. The remaining reaction conditions were consistent with the MB single-component degradation experiment. A total of 18 cycles were performed, and the results are as follows: Figure 3As shown in B. The results show that after 18 cycles of use, the degradation efficiency of the composite material for MB remains above 95%, with no significant attenuation, confirming its excellent structural stability and catalytic activity stability, enabling long-term repeated use and significantly reducing the cost of practical applications.

[0079] 4. Test on ability to resist interference from free radical scavengers

[0080] Using MB as the target pollutant, five free radical scavengers—TEOA (hole scavenger), IPA (hydroxyl radical scavenger), BQ (superoxide radical scavenger), EDTA (singlet oxygen scavenger), and AgNO3 (electron capture agent)—were added to the reaction system. The remaining reaction conditions were consistent with those in the MB single-component degradation experiment. The degradation efficiency after 1 minute of natural light irradiation was tested, and the results are as follows: Figure 3 As shown in Figure C. The results show that even in the presence of multiple free radical scavengers, the degradation efficiency of the composite material for MB remains above 97%, confirming that its degradation process does not depend on a single free radical pathway, possesses excellent anti-interference ability, and can maintain stable catalytic performance in complex wastewater systems.

[0081] Photocatalytic mechanism analysis

[0082] The excellent photocatalytic performance of the CeO2 / cGO nanocomposite material prepared in this invention stems from the synergistic optimization of its structure and electronic properties:

[0083] The narrow bandgap of the composite material (1.66 eV) allows it to fully absorb visible light, generating photogenerated electron-hole pairs. cGO, as an excellent electron acceptor and transport medium, rapidly captures and transfers photogenerated electrons through Ce-OC interfacial bonding, effectively suppressing electron-hole recombination and significantly improving quantum efficiency. The separated photogenerated electrons react with oxygen in the water to generate O2. - Photogenerated holes react with water / hydroxyl radicals in the water to generate •OH, and at the same time, a large amount of ¹O2 is generated in the reaction system. Multiple strong oxidizing active species work together to quickly oxidize and decompose organic pollutants into harmless small molecules.

[0084] The two-dimensional layered structure of cGO has an ultra-large specific surface area, which can rapidly adsorb and enrich organic pollutants in water through π-π conjugation, thereby increasing the local concentration of pollutants on the catalyst surface and allowing them to fully contact the active species, further accelerating the degradation reaction rate. The strong Ce-OC chemical bond between CeO2 and cGO avoids the shedding and aggregation of CeO2 nanoparticles during the catalytic process. At the same time, the structural stability of cGO ensures that the composite material can maintain its complete structure and catalytic activity during multiple cycles of use, achieving long-term stable application.

[0085] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a broad-spectrum high-efficiency visible light catalyst CeO2 / cGO nanocomposite, characterized in that, Includes the following steps: S1. Graphene oxide (GO) was ultrasonically dispersed in deionized water at room temperature, hydrogen peroxide was added, and the mixture was stirred at 60-65°C for no less than 24 hours. After the reaction was completed, the mixture was centrifuged and washed to obtain carboxyl-rich graphene oxide (cGO). S2. The obtained carboxyl-rich graphene oxide (cGO) was dispersed in deionized water, and N,N-dimethylformamide (DMF) and cerium salt were added. The mixture was refluxed at 130-132°C for 5-6 hours. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain CeO2 / cGO nanocomposite material.

2. The method for preparing a broad-spectrum, high-efficiency visible light photocatalyst CeO2 / cGO nanocomposite material according to claim 1, characterized in that, In step S2, the cerium salt is any one or a combination of cerium nitrate, cerium chloride, and cerium sulfate.

3. The method for preparing a broad-spectrum, high-efficiency visible light photocatalyst CeO2 / cGO nanocomposite material according to claim 1, characterized in that, In step S2, the ratio of cerium salt, deionized water and N,N-dimethylformamide is 2g:20-30mL:200-300mL.

4. The CeO2 / cGO nanocomposite material for broad-spectrum and high-efficiency visible light photocatalyst prepared by any one of claims 1 to 3.

5. The CeO2 / cGO nanocomposite material according to claim 4, characterized in that, The composite material uses carboxyl-rich graphene oxide (cGO) as a carrier, and nano-CeO2 particles with a particle size of 5-15 nm are uniformly loaded on the surface of the cGO. The nano-CeO2 particles and cGO form a Ce-OC interface chemical bond, and the optical band gap of the composite material is 1.66 eV.

6. The application of the CeO2 / cGO nanocomposite material according to claim 5 in the degradation of organic pollutants in water under natural or visible light conditions.

7. The application of the CeO2 / cGO nanocomposite material according to claim 6, characterized in that, The organic pollutants include any one or more combinations of organic dyes, antibiotics, phenolic endocrine disruptors, and algal toxins; The organic dye is methylene blue (MB) or rhodamine B (RhB); the antibiotic is norfloxacin (NOR) or tetracycline (TC); the phenolic endocrine disruptor is bisphenol A (BPA); and the algal toxin is microcystin-LR (MC-LR).

8. The application of the CeO2 / cGO nanocomposite material according to claim 7, characterized in that, Under natural light irradiation, the CeO2 / cGO nanocomposite material exhibits a degradation rate of over 99% for MB, RhB, NOR, TC, and MC-LR within 1 minute, and a degradation rate of over 90% for BPA within 1 minute.

9. The application of the CeO2 / cGO nanocomposite material according to claim 6, characterized in that, The water body refers to an aquatic environment with a pH value of 2-12, as well as natural aquatic environments such as tap water, pond water, and river water.

10. The application of the CeO2 / cGO nanocomposite material according to claim 7, characterized in that, The CeO2 / cGO nanocomposite material maintains stable degradation performance against all target organic pollutants; and after being recycled 18 times, the degradation efficiency of MB is still higher than 95%.

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