Cu2O@noble metal composite particles with Yolk-Shell structure, their preparation methods and applications

Abstract

The application provides a preparation method of Cu2O@ noble metal composite particles with Yolk-Shell structure, octahedral Cu2O particles are prepared by adding sodium hydroxide solution and reducing agent powder into copper sulfate pentahydrate solution at a specific temperature; then the octahedral Cu2O particles are dispersed in ethylene glycol solution, sodium hydroxide solution and reducing agent solution are added in sequence, and Cu2O@Cu composite particles with Yolk-Shell structure are obtained by reaction at a specific temperature; then the Cu2O@Cu composite particles are dispersed in water, noble metal acid solution is added, and stirring reaction is carried out at normal temperature for a certain time, so that Cu2O@ noble metal composite particles with Yolk-Shell structure are obtained. Through twice in-situ reactions, the application realizes controllable preparation of Cu2O@ noble metal composite particles with Yolk-Shell structure, the whole particle is octahedral structure, Cu2O is Yolk, and the multi-phase structure composed of uniformly dispersed noble metal particles and Cu2O particles is Shell, the composite particle has stronger light absorption efficiency and rich surface active sites, and the generation of carriers and the rapid transfer of charges are enhanced.

Description

Technical Field

[0001] This invention relates to the field of photocatalyst technology, specifically to a Cu2O@noble metal composite particle with a Yolk-Shell structure, its preparation method, and its application. Background Technology

[0002] With economic development, water pollution has become increasingly prominent, particularly the long time required for the natural degradation of organic dyes and antibiotics. Cuprous oxide (Cu2O), as a narrow-bandgap semiconductor material, can effectively absorb visible light from the sun and has great potential for photocatalytic degradation of organic matter. However, Cu2O also suffers from drawbacks such as low quantum efficiency and easy recombination of charge carriers, thus requiring composites with other materials. Due to the unique localized surface plasmon resonance effect of noble metal particles, the excitation and migration of charge carriers in composite particles formed by Cu2O and noble metal particles are closely related to the material's composition, distribution, and size. Therefore, designing and synthesizing cuprous oxide-based composite materials with special structures and excellent properties remains a key issue that urgently needs to be addressed.

[0003] The Yolk-Shell structure offers a novel approach to the synthesis of composite particles. A typical Yolk-Shell structure consists of a hollow shell and a core, which effectively enhances light scattering within the hollow space, improving light absorption efficiency and thus significantly increasing carrier generation and separation efficiency. Current preparation methods typically use a single-phase noble metal particle as the shell, failing to effectively utilize the abundant active sites on the surface to achieve charge transfer between the noble metal and Cu2O. Therefore, designing and preparing a composite particle with Cu2O as the Yolk and a multiphase structure consisting of uniformly dispersed noble metal particles and Cu2O particles as the shell presents a significant challenge. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing Cu2O@noble metal composite particles with a Yolk-Shell structure. The method prepares a composite particle with Cu2O as the Yolk and a multiphase structure composed of uniformly dispersed noble metal particles and Cu2O particles as the Shell, which provides stronger light absorption efficiency and more abundant surface active sites, thereby enhancing the generation of charge carriers and the rapid transfer of charge.

[0005] This invention provides a method for preparing Cu2O@noble metal composite particles with a Yolk-Shell structure, comprising the following steps:

[0006] (1) At a specific temperature, a certain concentration of sodium hydroxide solution is added to a copper sulfate pentahydrate solution of a certain concentration. After reacting for a certain time, a reducing agent powder is added. After reacting for a certain time, the mixture is centrifuged and the resulting solid is dried to obtain octahedral Cu2O particles.

[0007] (2) Disperse the octahedral Cu2O particles obtained in step (1) in ethylene glycol solution, add a certain concentration of sodium hydroxide solution at a specific temperature, then add a certain concentration of reducing agent solution, react at a specific temperature for a certain time, centrifuge and separate the solid obtained, and dry the solid to obtain Cu2O@Cu composite particles with Yolk-Shell structure.

[0008] (3) Disperse the Cu2O@Cu composite particles obtained in step (2) in water, add a certain concentration of noble metal acid solution, stir and react at room temperature for a certain time, and then centrifuge, wash and vacuum dry to obtain Cu2O@noble metal composite particles with Yolk-Shell structure.

[0009] Preferably, the reducing agent in steps (1) and (2) is glucose or hydroquinone.

[0010] Preferably, in step (1), the amounts of each reagent are copper sulfate pentahydrate: sodium hydroxide: reducing agent powder = (1.8-2.7) mol: (15-17.5) mol: (400-600) g, the concentration of the copper sulfate pentahydrate solution is (0.06-0.07) mol / L, and the concentration of the sodium hydroxide solution is (6-7) mol / L.

[0011] Preferably, the reaction conditions in step (1) are constant temperature water bath heating and stirring, the reaction temperature is 55℃, and the reaction time is (0.5~1.5)h.

[0012] Preferably, in step (2), the amounts of each reagent are Cu2O: sodium hydroxide: reducing agent = 120g: (200-250)mol: (50-150)mol, the concentration of Cu2O particles in step (2) is 0.8g / L, the concentration of sodium hydroxide solution is (4-5)mol / L, and the concentration of reducing agent solution is (1-3)mol / L.

[0013] Preferably, the reaction conditions in step (2) are constant temperature water bath heating and stirring, the reaction temperature is 60℃, and the reaction time is (0.5~1)h.

[0014] Preferably, in step (3), the amount of each reagent used is Cu2O@Cu: noble metal acid = 40g: (4~20)mmol, the concentration of Cu2O@Cu particle dispersion is (0.5~0.6)g / L, the concentration of noble metal acid solution is (2~10)mmol / L, and the noble metal acid solution is chloroauric acid solution or chloroplatinic acid or a mixture of the two.

[0015] Preferably, the reaction method in step (3) is magnetic stirring, and the stirring reaction time is (0.5-1)h; the washing in step (3) uses deionized water and anhydrous ethanol, the vacuum drying temperature is (40-60)℃, and the drying time is (2-4)h.

[0016] The present invention also discloses a Cu2O@noble metal composite particle with a Yolk-Shell structure, wherein Cu2O is the Yolk and the multiphase structure composed of uniformly dispersed noble metal particles and Cu2O particles is the Shell.

[0017] The present invention also discloses an application of Cu2O@noble metal composite particles with a Yolk-Shell structure, wherein the Cu2O@noble metal composite particles with a Yolk-Shell structure are used as catalysts for photocatalytic degradation of organic matter.

[0018] The working principle of this invention is as follows: The method for preparing Cu2O@noble metal composite particles with a Yolk-Shell structure involves first dispersing octahedral Cu2O particles in an ethylene glycol solution, then adding a sodium hydroxide solution of a certain concentration at a specific temperature, followed by the addition of a reducing agent solution of a certain concentration. The reaction proceeds at a specific temperature, reducing some of the Cu2O in situ to a Cu particle-based shell, thus obtaining Cu2O@Cu composite particles with a Yolk-Shell structure. Next, the Cu2O@Cu composite particles are dispersed in water, and a noble metal acid solution of a certain concentration is added. The mixture is stirred at room temperature, and through a substitution reaction between Cu and noble metal ions, the Cu particle-based shell is replaced with a multiphase shell composed of noble metal particles and Cu2O particles, thus obtaining Cu2O@noble metal composite particles with a Yolk-Shell structure. Ethylene glycol exhibits reducing properties upon heating. Under the combined action of the ethylene glycol solution and the reducing agent solution, the monovalent copper in cuprous oxide particles is reduced to zero-valent copper, subsequently forming nuclei and in-situ nanoparticles. As time progresses, the number of copper particles increases, eventually forming a shell composed of Cu nanoparticles. Therefore, using ethylene glycol as the reaction medium in this invention is essential, because in aqueous solutions, a simple reducing solution cannot reduce monovalent copper to zero-valent copper.

[0019] The beneficial effects of this invention are:

[0020] (1) The method of the present invention is simple, and the water bath heating and stirring are highly operable and have good repeatability;

[0021] (2) This invention achieves the controllable preparation of Cu2O@noble metal composite particles with Yolk-Shell structure through two in-situ reactions. The particles are octahedral in structure, Cu2O is Yolk, and the multiphase structure composed of uniformly dispersed noble metal particles and Cu2O particles is Shell.

[0022] (3) The Cu2O@noble metal composite particles with Yolk-Shell structure prepared by the present invention have stronger light absorption efficiency and abundant surface active sites, which enhance the generation of charge carriers and the rapid transfer of charge. Attached Figure Description

[0023] Figure 1 These are scanning electron microscope images, transmission electron microscope images, and energy dispersive spectroscopy (EDS) elemental distribution diagrams of Cu2O@Au composite particles with a Yolk-Shell structure prepared in this invention.

[0024] Figure 2 These are scanning electron microscope images, transmission electron microscope images, and energy dispersive spectroscopy (EDS) elemental distribution diagrams of Cu2O@Pt composite particles with a Yolk-Shell structure prepared in this invention.

[0025] Figure 3 These are scanning electron microscope images, transmission electron microscope images, and energy dispersive spectroscopy (EDS) images of Cu2O@Au / Pt composite particles with a Yolk-Shell structure prepared in this invention.

[0026] Figure 4 The graph shows the degradation rate of methyl orange under visible light for the composite particles prepared in Examples 1 to 3. Detailed Implementation

[0027] To make the technical solution of the present invention easier to understand, the technical solution of the present invention will now be clearly and completely described in conjunction with the accompanying drawings and specific embodiments.

[0028] Example 1:

[0029] The preparation method of Cu2O@noble metal composite particles with a Yolk-Shell structure in this embodiment includes the following steps:

[0030] (1) Dissolve copper sulfate pentahydrate in 30 mL of deionized water to prepare a copper salt solution of 0.06 mol / L. Stir continuously at 500 rpm in a 55 °C water bath. Then slowly add 25 mL of sodium hydroxide solution of 6.5 mol / L to the copper salt solution to generate a brown flocculent precipitate. After 5 minutes, add 0.5 g of hydroquinone powder. After reacting for 1 hour, centrifuge and dry the brick red powder to obtain octahedral cuprous oxide particles.

[0031] (2) 120g of octahedral cuprous oxide particles were ultrasonically dispersed in 150mL of ethylene glycol solution. The mixture was continuously stirred at 500rpm in a 60℃ water bath. 50mL of 4.5mol / L sodium hydroxide solution was added dropwise, followed by 50mL of 2.2mol / L glucose solution. After reacting for 1 hour, the resulting dark red powder was centrifuged and dried to obtain Cu2O@Cu particles with a Yolk-Shell structure.

[0032] (3) Disperse 40g of Cu2O@Cu particles in 70mL of deionized water, add 2mL of chloroauric acid solution with a concentration of 5mmol / L, stir and react for 1 hour at room temperature and pressure, centrifuge at 8000rpm for 2 minutes, collect and dry the black-red particle powder obtained, and Cu2O@Au composite particles with Yolk-Shell structure can be obtained.

[0033] Scanning electron microscope (SEM) images, transmission electron microscope (TEM) images, and elemental distribution images of the Cu₂O@Au composite particles with a Yolk-Shell structure prepared in this embodiment are shown below. Figure 1 As shown, this demonstrates that the composite micron particles have an octahedral Yolk-Shell structure, and that Cu2O is Yolk, while the biphase structure composed of uniformly dispersed Au nanoparticles and Cu2O nanoparticles is Shell.

[0034] Example 2:

[0035] The preparation method of Cu2O@noble metal composite particles with a Yolk-Shell structure in this embodiment includes the following steps:

[0036] (1) Dissolve copper sulfate pentahydrate in 30 mL of deionized water to prepare a copper salt solution of 0.065 mol / L. Stir continuously at 500 rpm in a 55 °C water bath. Then slowly add 25 mL of 6.0 mol / L sodium hydroxide solution to the copper salt solution to generate a brown flocculent precipitate. After 5 minutes, add 0.5 g of hydroquinone powder. After reacting for 1.5 hours, centrifuge and dry the brick-red powder to obtain octahedral cuprous oxide particles.

[0037] (2) 120g of octahedral cuprous oxide particles were ultrasonically dispersed in 150mL of ethylene glycol solution. The mixture was continuously stirred at 500rpm in a 60℃ water bath. 50mL of 4mol / L sodium hydroxide solution was added dropwise, followed by 50mL of 1.1mol / L glucose solution. After reacting for 30 minutes, the resulting dark red powder was centrifuged and dried to obtain Cu2O@Cu particles with a Yolk-Shell structure.

[0038] (3) Disperse 40g of Cu2O@Cu particles in 70mL of deionized water, add 1mL of 2mmol / L chloroplatinic acid solution, stir and react for 30 minutes at room temperature and pressure, centrifuge at 8000rpm for 2 minutes, collect and dry the black-red particle powder to obtain Cu2O@Pt composite particles with Yolk-Shell structure.

[0039] Scanning electron microscope (SEM) images, transmission electron microscope (TEM) images, and elemental distribution images of the Cu₂O@Pt composite particles with a Yolk-Shell structure prepared in this embodiment are shown below. Figure 2 As shown, this demonstrates that the composite micron particles have an octahedral Yolk-Shell structure, and that Cu2O is Yolk, while the biphase structure composed of uniformly dispersed Pt nanoparticles and Cu2O nanoparticles is Shell.

[0040] Example 3:

[0041] The preparation method of Cu2O@noble metal composite particles with a Yolk-Shell structure in this embodiment includes the following steps:

[0042] (1) Dissolve copper sulfate pentahydrate in 30 mL of deionized water to prepare a copper salt solution of 0.07 mol / L. Stir continuously at 500 rpm in a 55 °C water bath. Then slowly add 25 mL of sodium hydroxide solution with a concentration of 7.0 mol / L to the copper salt solution to generate a brown flocculent precipitate. After 5 minutes, add 0.5 g of hydroquinone powder. After reacting for 1 hour, centrifuge and dry the brick-red powder to obtain octahedral cuprous oxide particles.

[0043] (2) 120g of octahedral cuprous oxide particles were ultrasonically dispersed in 150mL of ethylene glycol solution. The mixture was continuously stirred at 500rpm in a 60℃ water bath. 50mL of 5mol / L sodium hydroxide solution was added dropwise, followed by 50mL of 3.0mol / L glucose solution. After reacting for 45 minutes, the resulting dark red powder was centrifuged and dried to obtain Cu2O@Cu particles with a Yolk-Shell structure.

[0044] (3) Disperse 40g of Cu2O@Cu particles in 70mL of deionized water, and add 0.75mL of 10mmol / L chloroauric acid solution and 1.25mL of 5mol / L chloroplatinic acid solution. Stir the reaction at room temperature and pressure for 45 minutes. After centrifuging at 8000rpm for 2 minutes, collect and dry the resulting black-red particle powder to obtain Cu2O@Au / Pt composite particles with Yolk-Shell structure.

[0045] Scanning electron microscope (SEM) images, transmission electron microscope (TEM) images, and elemental distribution images of the Cu₂O@Au / Pt composite particles with a Yolk-Shell structure prepared in this embodiment are shown below. Figure 3 As shown, this demonstrates that the composite micron particles have an octahedral Yolk-Shell structure, and that Cu2O is Yolk, while the three-phase structure composed of uniformly dispersed Au nanoparticles, Pt nanoparticles, and Cu2O nanoparticles is Shell.

[0046] Experimental example:

[0047] This experiment used catalysts—no catalyst, Cu2O@Au composite particles with a Yolk-Shell structure prepared in Example 1, Cu2O@Pt composite particles with a Yolk-Shell structure prepared in Example 2, and Cu2O@Au / Pt composite particles with a Yolk-Shell structure prepared in Example 3—to verify the degradation effect of methyl orange under visible light. The specific procedure was as follows: 10 mg of catalyst powder was added to 50 mL of a 20 mg / L methyl orange solution. First, the mixture was stirred in the dark for 30 minutes to allow the powder to reach adsorption saturation. Then, a 300W xenon lamp with a 420 nm filter was used to simulate visible light, and the concentration of the methyl orange solution was tested at different time points to calculate the degradation efficiency.

[0048]

[0049] It should be noted that the embodiments described herein are only some embodiments of the present invention, and not all implementations of the present invention. These embodiments are merely illustrative and are intended only to provide a more intuitive and clear way to understand the content of the present invention, not to limit the technical solutions described herein. All other implementation methods that can be conceived by those skilled in the art without creative effort, as well as other simple substitutions and variations of the technical solutions of the present invention, without departing from the concept of the present invention, are within the protection scope of the present invention.

Claims

1. A method for preparing Cu2O@noble metal composite particles with a Yolk-Shell structure, characterized in that, Includes the following steps: (1) At 55℃, a certain concentration of sodium hydroxide solution was added to a copper sulfate pentahydrate solution of a certain concentration. After reacting for a certain time, a reducing agent powder was added. After reacting for a certain time, the mixture was centrifuged and the resulting solid was dried to obtain octahedral Cu2O particles. (2) Disperse the octahedral Cu2O particles obtained in step (1) in an ethylene glycol solution. First, add a certain concentration of sodium hydroxide solution at 60°C, then add a certain concentration of reducing agent solution. After reacting for a certain time at a specific temperature, centrifuge and dry the resulting solid to obtain Cu2O@Cu composite particles with a Yolk-Shell structure. The amount of each reagent is Cu2O: sodium hydroxide: reducing agent = 120g: (200~250)mol: (50~150)mol, the concentration of Cu2O particle dispersion is 0.8g / L, the concentration of sodium hydroxide solution is (4~5)mol / L, and the concentration of reducing agent solution is (1~3)mol / L. The reaction conditions are constant temperature water bath heating and stirring, reaction temperature is 60°C, and reaction time is (0.5~1)h. (3) Disperse the Cu2O@Cu composite particles obtained in step (2) in water, add a certain concentration of noble metal acid solution, stir and react at room temperature for a certain time, and then centrifuge, wash and vacuum dry to obtain Cu2O@noble metal composite particles with Yolk-Shell structure; the noble metal acid solution is chloroauric acid solution or chloroplatinic acid or a mixture of the two.

2. The method for preparing Cu2O@noble metal composite particles with a Yolk-Shell structure as described in claim 1, characterized in that, The reducing agent in steps (1) and (2) is glucose or hydroquinone.

3. The method for preparing Cu2O@noble metal composite particles with a Yolk-Shell structure as described in claim 1, characterized in that, In step (1), the amounts of each reagent are copper sulfate pentahydrate: sodium hydroxide: reducing agent powder = (1.8~2.7) mol: (150~175) mol: (400~600) g, the concentration of copper sulfate pentahydrate solution is (0.06~0.07) mol / L, and the concentration of sodium hydroxide solution is (6~7) mol / L.

4. The method for preparing Cu2O@noble metal composite particles with a Yolk-Shell structure as described in claim 1, characterized in that, In step (1), the reaction conditions are constant temperature water bath heating and stirring, the reaction temperature is 55℃, and the reaction time is (0.5~1.5)h.

5. The method for preparing Cu2O@noble metal composite particles with a Yolk-Shell structure as described in claim 1, characterized in that, In step (3), the amount of each reagent used is Cu2O@Cu: noble metal acid = 40g: (4~20)mmol, the concentration of Cu2O@Cu particle dispersion is (0.5~0.6)g / L, and the concentration of noble metal acid solution is (2~10)mmol / L.

6. The method for preparing Cu2O@noble metal composite particles with a Yolk-Shell structure as described in claim 1, characterized in that, In step (3), the reaction method is magnetic stirring, and the stirring reaction time is (0.5~1)h; in step (3), the washing method is deionized water and anhydrous ethanol, the vacuum drying temperature is (40~60)℃, and the drying time is (2~4)h.

7. A Cu2O@noble metal composite particle with a Yolk-Shell structure, characterized in that, The Cu2O@noble metal composite particles with a Yolk-Shell structure are prepared by the preparation method according to any one of claims 1 to 6. The Cu2O@noble metal composite particles with a Yolk-Shell structure use Cu2O as the Yolk and a multiphase structure composed of uniformly dispersed noble metal particles and Cu2O particles as the Shell.

8. An application of Cu2O@noble metal composite particles with a Yolk-Shell structure, characterized in that, The Cu2O@noble metal composite particles with a Yolk-Shell structure as described in claim 7 are used as catalysts for photocatalytic degradation of organic matter.

Images