A core-shell type Au@CeO2@PDA photocatalyst, its preparation method and application

Abstract

This invention provides a core-shell Au@CeO2@PDA photocatalyst, its preparation method, and its application, belonging to the field of photocatalyst technology. The invention prepares a core-shell Au@CeO2@PDA photocatalyst, wherein the photocatalyst has a core-shell structure, with Au as the core and CeO2 as the outer shell, and PDA coating and modifying the outermost layer of the CeO2 shell. The particle size of the photocatalyst is 50–80 nm. The preparation method of the photocatalyst is simple, and it exhibits high catalytic degradation activity for organic pollutants and good cycling stability. It can photocatalytically degrade organic pollutants under visible light, demonstrating excellent practicality.

Description

Technical Field

[0001] This invention belongs to the field of photocatalyst technology, specifically relating to a core-shell type Au@CeO2@PDA photocatalyst, its preparation method, and its application. Background Technology

[0002] With the development of industry and transportation, water pollution has become one of the most pressing issues. Common water pollution problems mainly involve the discharge of industrial waste liquids and gases into water bodies, where large amounts of toxic organic matter accumulate, posing a significant threat to human health. Traditional methods are difficult to completely degrade organic matter in water bodies, while photocatalysis technology, due to its low cost, green and pollution-free nature, energy efficiency, and other characteristics, has attracted significant attention from scholars and has become one of the current popular research areas.

[0003] Currently, plasmonic metal@semiconductor core-shell nanoparticles are considered a promising material in the field of photocatalysis. The effect of visible light interacting with plasmonic metals to generate thermally free carriers (electron-hole pairs) is called the localized surface plasmon resonance (LSPR) effect. Because gold has a high free electron density in the visible light region, the energy stored in LSPR excitation enhances near-electric field radiation near the nanoparticle surface through radiation, thereby promoting light energy absorption and conversion efficiency. Since pure plasmonic nanoparticles have poor electron transfer efficiency without the addition of sensitizers, coupling with semiconductors is generally used to improve the utilization efficiency of LSPR excitation. Dopamine (DA), under specific conditions, can be oxidized and self-polymerized into polydopamine (PDA), and is commonly used as a modifier for nanomaterial interfaces to impart functionality. The PDA structural fragment is a conjugated system containing abundant π-electron clouds, capable of adsorbing small molecules. Therefore, PDA coating has become one of the most readily available and universal surface modification methods. Combining the characteristics of the above materials, it is hoped that a highly efficient and stable photocatalyst can be prepared. Summary of the Invention

[0004] To address some shortcomings in existing technologies, this invention provides a core-shell Au@CeO2@PDA photocatalyst, its preparation method, and its applications. This invention prepares a core-shell Au@CeO2@PDA photocatalyst, wherein the photocatalyst has a core-shell structure, with Au as the core and CeO2 as the outer shell, and PDA coating the outermost layer of the CeO2 shell. The particle size of the photocatalyst is 50–80 nm. The preparation method of the photocatalyst is simple, and it exhibits high catalytic activity for degrading organic pollutants and good cycle stability. It can photocatalytically degrade organic pollutants under visible light, demonstrating excellent practicality.

[0005] To achieve the above-mentioned technical objectives, the present invention employs the following technical means:

[0006] The present invention first provides a core-shell Au@CeO2@PDA photocatalyst, wherein the photocatalyst has a core-shell structure, wherein Au is the core, CeO2 is the outer shell, and PDA is coated and modified on the outermost layer of the CeO2 shell; the particle size of the photocatalyst is 50-80 nm.

[0007] This invention also provides a method for preparing the above-mentioned core-shell Au@CeO2@PDA photocatalyst, the method comprising:

[0008] (1) Chloroauric acid aqueous solution and trisodium citrate aqueous solution were mixed and refluxed to obtain Au nanocolloid solution after the reaction was completed;

[0009] (2) The obtained Au nanocolloid solution was added to distilled water and sonicated. Then sodium carbonate and cerium nitrate were added and refluxed. After the reaction was completed, the mixture was centrifuged, washed, dried and then calcined in air to obtain Au@CeO2.

[0010] (3) Add Au@CeO2 to tris-HCl buffer solution, mix evenly by ultrasonication, then add dopamine hydrochloride, stir the reaction at room temperature, centrifuge, wash and dry after the reaction is completed to obtain core-shell type Au@CeO2@PDA photocatalyst.

[0011] Preferably, in step (1), the volume ratio of chloroauric acid aqueous solution and trisodium citrate aqueous solution is 0.8 mL: 25 mL; wherein the concentration of chloroauric acid is 20-30 mM and the concentration of trisodium citrate is 30-40 mM.

[0012] Preferably, in step (1), the reflux reaction conditions are: reacting at 90-120°C for 15-30 minutes.

[0013] Preferably, in step (2), the amount of Au nanocolloid solution used is 5-15 mL; the molar ratio of sodium carbonate to cerium nitrate is 1:1.

[0014] Preferably, in step (2), the reflux reaction conditions are: reacting at 90°C for 8 to 16 hours;

[0015] The calcination conditions are: reacting at 500–800℃ for 2–5 hours.

[0016] Preferably, in step (3), the ratio of Au@CeO2 to dopamine hydrochloride is 10 mg: 1-2 mg; and the pH of the tris-HCl buffer solution is 8.5.

[0017] Preferably, in step (3), the stirring reaction time is 2 to 8 hours.

[0018] This invention also provides the application of the above-mentioned core-shell Au@CeO2@PDA photocatalyst in the visible light photocatalytic degradation of organic pollutants.

[0019] Preferably, the organic pollutant includes one or more of toluene, p-phenol, bisphenol A, and tetracycline.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The catalyst described in this invention has high catalytic activity for degrading organic pollutants and good cycle stability. The electronic interaction between the Au core and the CeO2 shell leads to Ce 3+ The enrichment of active materials reduces the band gap energy of the CeO2 shell to the visible light region, while the energy stored in the LSPR decays, thereby promoting the generation and transfer of photogenerated carriers and enhancing the catalytic activity under visible light.

[0022] (2) The catalyst described in this invention is coated with PDA, which gives the plasma metal@semiconductor core-shell structure material more functionalization. The PDA structure contains a rich π electron cloud, which can generate π-π interaction with other molecules containing π system, thereby improving the adsorption performance of Au@CeO2 catalyst. At the same time, the PDA structure contains double bond, which can react with functional groups such as -NH2 and -SH, and can be further functionalized.

[0023] (3) The catalyst of the present invention can achieve efficient and stable organic matter degradation performance under room temperature liquid-solid reaction conditions. After 5 cycles of testing, the catalytic activity of the catalyst decreases by no more than 5%. Compared with the ~75% degradation rate of other Cu / g-C3N4 catalysts with LSPR effect, the degradation rate of the catalyst is increased by 6-10%. Attached Figure Description

[0024] Figure 1 Transmission electron microscope image of the core-shell Au@CeO2@PDA photocatalyst prepared in Example 1.

[0025] Figure 2 Transmission electron microscope image of the core-shell Au@CeO2@PDA photocatalyst prepared in Example 2.

[0026] Figure 3 Transmission electron microscope image of the core-shell Au@CeO2@PDA photocatalyst prepared in Example 3.

[0027] Figure 4 The degradation effect diagrams are for the core-shell Au@CeO2@PDA photocatalysts prepared in Examples 1-3.

[0028] Figure 5The cycling performance diagrams are for the core-shell Au@CeO2@PDA photocatalysts prepared in Examples 1-3. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0030] Example 1: Preparation of core-shell Au@CeO2@PDA photocatalyst

[0031] (1) Mix 0.8 mL of chloroauric acid aqueous solution (25 mM) and 25 mL of trisodium citrate aqueous solution (34 mM) evenly, reflux at 97 °C for 20 min, and cool naturally to room temperature after the reaction to obtain wine-red Au nanocolloid solution.

[0032] (2) Take 10 mL of Au nanocolloid solution and add it to 10 mL of distilled water. After ultrasonic dispersion, add 5 mM sodium carbonate and 5 mM cerium nitrate. Reflux at 90 °C for 12 h. After the product cools naturally to room temperature, centrifuge and wash with ethanol and distilled water three times respectively. After drying, calcine in air at 500 °C for 2 h to obtain Au@CeO2.

[0033] (3) Take 10 mg Au@CeO2 and disperse it in tris-HCl buffer solution, add 1 mg dopamine hydrochloride, stir at room temperature for 2 h, after the reaction is completed, centrifuge, wash the product 3 times with distilled water, and dry to obtain core-shell type Au@CeO2@PDA photocatalyst.

[0034] Figure 1 The image shows a transmission electron microscope (TEM) image of a core-shell Au@CeO2@PDA photocatalyst. As can be seen from the image, the photocatalyst has a core-shell structure, with Au as the core and CeO2 as the outer shell. PDA is coated and modified on the outermost layer of the CeO2 shell. The PDA, as an outer layer modification, can be used to connect other nanoparticles. The particle size of the photocatalyst is 50–80 nm.

[0035] This embodiment also investigated the ability of the prepared core-shell Au@CeO2@PDA photocatalyst to photocatalytically degrade toluene under visible light. The specific steps are as follows:

[0036] 50 mg of core-shell Au@CeO2@PDA photocatalyst was added to 100 mL of a 10 mg / L toluene aqueous solution. After equilibration in the dark for 30 min, a 300 W xenon lamp was used as the light source to carry out the photocatalytic degradation reaction at room temperature. Samples were taken every 30 min, and the concentration of the samples was determined using a UV spectrophotometer. The results are as follows: Figure 4 As shown.

[0037] from Figure 4It can be seen that the core-shell Au@CeO2@PDA photocatalyst prepared in this embodiment has a degradation rate of 85.1% for toluene within 240 min.

[0038] Example 2: Preparation of core-shell Au@CeO2@PDA photocatalyst

[0039] (1) Mix 0.8 mL of chloroauric acid aqueous solution (25 mM) and 25 mL of trisodium citrate aqueous solution (34 mM) evenly, reflux at 97 °C for 20 min, and cool naturally to room temperature after the reaction to obtain wine-red Au nanocolloid solution.

[0040] (2) Take 10 mL of Au nanocolloid solution and add it to 10 mL of distilled water. After ultrasonic dispersion, add 5 mM sodium carbonate and 5 mM cerium nitrate. Reflux at 90 °C for 12 h. After the product cools naturally to room temperature, centrifuge and wash with ethanol and distilled water three times respectively. After drying, calcine in air at 600 °C for 3 h to obtain Au@CeO2.

[0041] (3) Take 10 mg Au@CeO2 and disperse it in tris-HCl buffer solution, add 1 mg dopamine hydrochloride, stir at room temperature for 4 h, after the reaction is completed, centrifuge, wash the product 3 times with distilled water, and dry to obtain core-shell type Au@CeO2@PDA photocatalyst.

[0042] Figure 2 The image shows a transmission electron microscope (TEM) image of a core-shell Au@CeO2@PDA photocatalyst. As can be seen from the image, the photocatalyst has a core-shell structure, with Au as the core and CeO2 as the outer shell. PDA is coated and modified on the outermost layer of the CeO2 shell. The PDA, as an outer layer modification, can be used to connect other nanoparticles. The particle size of the photocatalyst is 50–80 nm.

[0043] This embodiment also investigated the ability of the prepared core-shell Au@CeO2@PDA photocatalyst to photocatalytically degrade p-phenol under visible light. The specific steps are as follows:

[0044] 50 mg of core-shell Au@CeO2@PDA photocatalyst was added to 100 mL of 10 mg / L p-phenol ethanol solution. After equilibration in the dark for 30 min, a 300 W xenon lamp was used as the light source to carry out the photocatalytic degradation reaction at room temperature. Samples were taken every 30 min, and the concentration of the samples was determined using a UV spectrophotometer. The results are as follows: Figure 4 As shown.

[0045] from Figure 4 It can be seen that the core-shell Au@CeO2@PDA photocatalyst prepared in this embodiment has a degradation rate of 83.7% for p-phenol within 240 min.

[0046] Example 3: Preparation of core-shell Au@CeO2@PDA photocatalyst

[0047] (1) Mix 0.8 mL of chloroauric acid aqueous solution (25 mM) and 25 mL of trisodium citrate aqueous solution (34 mM) evenly, reflux at 97 °C for 20 min, and cool naturally to room temperature after the reaction to obtain wine-red Au nanocolloid solution.

[0048] (2) Take 10 mL of Au nanocolloid solution and add it to 10 mL of distilled water. After ultrasonic dispersion, add 5 mM sodium carbonate and 5 mM cerium nitrate. Reflux at 90 °C for 12 h. After the product cools naturally to room temperature, centrifuge and wash with ethanol and distilled water three times respectively. After drying, calcine at 700 °C for 4 h to obtain Au@CeO2.

[0049] (3) Take 10 mg Au@CeO2 and disperse it in tris-HCl buffer solution, add 1 mg dopamine hydrochloride, stir at room temperature for 6 h, after the reaction is completed, centrifuge, wash the product 3 times with distilled water, and dry to obtain core-shell type Au@CeO2@PDA photocatalyst.

[0050] Figure 3 The image shows a transmission electron microscope (TEM) image of a core-shell Au@CeO2@PDA photocatalyst. As can be seen from the image, the photocatalyst has a core-shell structure, with Au as the core and CeO2 as the outer shell. PDA is coated and modified on the outermost layer of the CeO2 shell. The PDA, as an outer layer modification, can be used to connect other nanoparticles. The particle size of the photocatalyst is 50–80 nm.

[0051] This embodiment also investigated the ability of the prepared core-shell Au@CeO2@PDA photocatalyst to photocatalytically degrade bisphenol A under visible light. The specific steps are as follows:

[0052] 50 mg of core-shell Au@CeO2@PDA photocatalyst was added to 100 mL of 10 mg / L bisphenol A ethanol solution. After equilibration in the dark for 30 min, a 300 W xenon lamp was used as the light source to carry out the photocatalytic degradation reaction at room temperature. Samples were taken every 30 min, and the concentration of the samples was determined using a UV spectrophotometer. The results are as follows: Figure 4 As shown.

[0053] from Figure 4 It can be seen that the core-shell Au@CeO2@PDA photocatalyst prepared in this embodiment has a degradation rate of 81.2% for p-phenol within 240 min.

[0054] The core-shell Au@CeO2@PDA photocatalysts prepared in Examples 1-3 were subjected to multiple cycle experiments to investigate their cyclic activity. The results are as follows: Figure 5 As shown. From Figure 5 It can be seen that the core-shell Au@CeO2@PDA photocatalysts prepared in Examples 1 to 3 have good cycling activity, and their degradation efficiency decreases by no more than 5% after 5 cycles.

[0055] In summary, this invention prepares a core-shell Au@CeO2@PDA photocatalyst. The photocatalyst has a core-shell structure, with Au as the core and CeO2 as the outer shell, and PDA coating the outermost layer of the CeO2 shell. The PDA, as an outer layer modification, can be used to connect other nanoparticles. The particle size of the photocatalyst is 50–80 nm. The preparation method of the photocatalyst is simple, and it has high catalytic activity for degrading organic pollutants and good cycling stability. It can photocatalytically degrade organic pollutants under visible light, and has good practicality.

[0056] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a core-shell type Au@CeO2@PDA photocatalyst, characterized in that, The method includes: (1) Chloroauric acid aqueous solution and trisodium citrate aqueous solution were mixed and refluxed to obtain Au nanocolloid solution after the reaction was completed; (2) The obtained Au nanocolloid solution was added to distilled water and sonicated. Then sodium carbonate and cerium nitrate were added and refluxed. After the reaction was completed, the solution was centrifuged, washed, dried, and then calcined in air to obtain Au@CeO2. The amount of Au nanocolloid solution used was 5~15mL. The molar ratio of sodium carbonate and cerium nitrate was 1:

1. (3) Add Au@CeO2 to tris-HCl buffer solution, mix evenly by ultrasonication, then add dopamine hydrochloride, stir the reaction at room temperature, centrifuge, wash and dry after the reaction is completed to obtain core-shell type Au@CeO2@PDA photocatalyst; The ratio of Au@CeO2 to dopamine hydrochloride is 10 mg: 1~2 mg; the pH of the tris-HCl buffer solution is 8.5; The stirring reaction time is 2-8 hours.

2. The preparation method of the core-shell Au@CeO2@PDA photocatalyst according to claim 1, characterized in that, In step (1), the volume ratio of chloroauric acid aqueous solution and trisodium citrate aqueous solution is 0.8 mL: 25 mL; wherein the concentration of chloroauric acid is 20~30 mM and the concentration of trisodium citrate is 30~40 mM.

3. The preparation method of the core-shell Au@CeO2@PDA photocatalyst according to claim 1, characterized in that, In step (1), the reflux reaction conditions are: reacting at 90~120℃ for 15~30 min.

4. The preparation method of the core-shell Au@CeO2@PDA photocatalyst according to claim 1, characterized in that, In step (2), the reflux reaction conditions are: reacting at 90°C for 8~16 hours.

5. The preparation method of the core-shell Au@CeO2@PDA photocatalyst according to claim 1, characterized in that, In step (2), the calcination conditions are: reacting at 500~800℃ for 2~5h.

6. The core-shell Au@CeO2@PDA photocatalyst prepared by the preparation method according to any one of claims 1 to 5, characterized in that, The photocatalyst has a core-shell structure, with Au as the core and CeO2 as the outer shell, and PDA is coated and modified on the outermost layer of the CeO2 shell; the particle size of the photocatalyst is 50~80nm.

7. The application of the core-shell Au@CeO2@PDA photocatalyst of claim 6 in the photocatalytic degradation of organic pollutants under visible light; wherein the organic pollutants include one or more of toluene, p-phenol, bisphenol A and tetracycline.

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