Polymer microsphere-assisted copper / carbon nitrogen composite material as well as preparation method and application thereof

Abstract

The invention provides a polymer microsphere-assisted copper / carbon nitrogen composite material as well as a preparation method and application thereof. The material is a composite material formed by loading copper nanoparticles on a carbon-nitrogen matrix, and the carbon-nitrogen matrix is of an amorphous structure and is loaded with monometallic copper or copper nanoparticles doped with cobalt, nickel, iron and zinc. A polymeric microsphere precursor containing copper nanoparticles obtained through hydrothermal synthesis is subjected to inert atmosphere high-temperature treatment, and the composition structure of the copper / carbon nitrogen composite material is regulated and controlled by adjusting high-temperature treatment conditions. The polymer microsphere-assisted copper / carbon nitrogen composite material is stable in structure, the synthesis method is safe and simple, and the polymer microsphere-assisted copper / carbon nitrogen composite material has excellent hydrogen production activity when being applied to photocatalytic water reaction and can be expanded in application in light and heat catalytic reaction.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials, relates to nano-catalytic materials, and is a polymer microsphere-assisted copper / carbon nitride composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Copper, as an important photocatalytic material, has a wide range of applications. Copper oxides, copper metal nanoparticles, and copper-based catalysts compounded with other materials exhibit good catalytic activity in reactions such as water splitting for hydrogen production and carbon dioxide reduction. Copper-based photocatalysts have attracted much attention due to their low cost and high catalytic activity.

[0003] The carrier in the photocatalyst plays a crucial role in the photocatalytic reaction. The carrier can effectively disperse the active components of the catalyst (such as metal nanoparticles or semiconductor particles, etc.). Better dispersion can increase the surface area of the catalyst, expose more active sites, and thus improve the catalytic efficiency. High-temperature treatment can remove organic substances or other impurities on the surface or inside the carrier, which helps to improve the performance of the catalyst, reduce the occurrence of side reactions, and at the same time improve the light absorption characteristics of the catalyst. For example, rapid high-temperature treatment of modified graphitic carbon nitride significantly increases the surface area, providing more active sites for the photocatalytic reaction (Zhang Y Z, et al., Applied Catalysis B: Environmental, 233(2018)80 - 87). The light absorption performance of zinc oxide (ZnO) obtained after high-temperature carbonization and annealing is significantly increased (Nazarkovsky M.A., et al., Journal of Photochemistry and Photobiology A: Chemistry, 334(2017)36 - 46). High-temperature treatment of encapsulated Ni CdS nanospheres transforms the crystal form of cadmium sulfide from cubic phase to hexagonal phase, releasing the active sites of Ni (BaJ B, et al., Journal of Catalysis, 414(2022)319 - 329), etc. So far, most of the reported high-temperature treatment materials are semiconductor materials or single organic polymers, and the materials obtained by high-temperature treatment of polymer microspheres containing copper nanoparticles in the present invention have not been reported. Summary of the Invention

[0004] The present invention provides a polymer microsphere-assisted copper / carbon nitride composite material, its preparation method and application. This method regulates the synthesis of metal catalytic materials through high-temperature treatment under an inert atmosphere. The high-temperature treatment reduces the particle size of the polymer microsphere precursor, resulting in more copper nanoparticles being exposed on the surface of the microspheres, forming copper nanoparticles supported on a specific carbon nitride matrix. This preparation method is simple and easy to implement. The obtained copper / carbon nitride composite material has excellent hydrogen production activity when applied to photocatalytic water reactions and is expected to be extended to the applications of other photo- and thermal-catalytic reactions.

[0005] The present invention prepares a polymer microsphere precursor containing copper nanoparticles by a hydrothermal method and obtains a copper / carbon nitride composite material with adjustable particle size through high-temperature treatment under an inert atmosphere. The copper / carbon nitride composite material is a composite material with copper nanoparticles supported on a carbon nitride matrix. Among them, the carbon nitride matrix is an amorphous structure, the mass percentage of copper is 15% - 50%, and the composite material is spherical particles with a size of 500 - 1000 nm.

[0006] The present invention provides a polymer microsphere-assisted copper / carbon nitride composite material, its preparation method and application, and adopts the following technical solutions:

[0007] Mix melamine, aqueous formaldehyde solution and a certain amount of copper metal precursor salt (or multiple metal precursor salts) (the molar amount of the metal precursor salt is 10% - 20% of that of melamine). The mixture is hydrothermally synthesized to obtain a polymer microsphere precursor containing copper nanoparticles, which is placed in an inert atmosphere, heated to a certain temperature at a rate of 5 °C / min and then held at a constant temperature for a period of time, and naturally cooled. The ground powder product is the polymer microsphere-assisted copper / carbon nitride composite material. It mainly has the following characteristics:

[0008] For the copper / carbon nitride composite material, the constant temperature during the heating treatment of the polymer microsphere precursor is 500 - 800 °C, and the constant temperature treatment time is 3 - 8 hours.

[0009] For the copper / carbon nitride composite material, the inert atmosphere during the treatment of the polymer microsphere precursor is continuously flowing nitrogen or argon, and the gas flow rate is 60 - 120 mL / min.

[0010] For the copper / carbon nitride composite material, the high-temperature treatment reduces the particle size of the polymer microsphere precursor, resulting in more copper nanoparticles being exposed on the surface of the microspheres.

[0011] The copper / carbon nitride composite material is a single-metal copper / carbon nitride composite material or a multi-metal doped copper / carbon nitride composite material, and the metal doping amount accounts for 0.25% - 0.4% of the mass of copper.

[0012] The doped metal of the copper / carbon nitride composite material includes at least one of cobalt, nickel, iron, and zinc, and the copper metal and the multi-metal precursor salt are at least one of nitrate, acetate, chloride, and sulfate.

[0013] In the copper / carbon nitride composite material, the copper nanoparticles are mainly in the zero-valent state, and a small amount of divalent copper coexists.

[0014] The copper / carbon nitride composite material is applied to the photocatalytic water reaction and exhibits excellent hydrogen production activity. Using the copper / carbon nitride composite material prepared by the present invention as a catalyst, hydrogen can be produced by catalyzing the decomposition of water under the irradiation of a xenon lamp light source, and its hydrogen production rate is much higher than that of the polymer precursor catalytic system.

[0015] Different from other heat-treated materials, the heat-treated material provided by the present invention is a polymer microsphere loaded with copper nanoparticles, and the copper / carbon nitride composite material is obtained by heat treatment in an inert atmosphere. The catalytic material prepared by this method has a smaller particle size and more copper nanoparticles exposed on the surface of the microsphere. The copper / carbon nitride composite material has better catalytic performance and is suitable for the preparation of metal catalytic materials supported on organic carriers. The present invention provides a polymer microsphere-assisted copper / carbon nitride composite material with a simple synthesis method, stable structure, and high yield, which is expected to be extended to the applications of other photo- and thermal catalytic reactions. Description of the Drawings

[0016] Figure 1 TEM (a) and HRTEM (b) diagrams of the copper / carbon nitride composite material prepared by the present invention;

[0017] Figure 2 XRD diagram of the copper / carbon nitride composite material prepared by the present invention;

[0018] Figure 3 XPS diagram of the copper / carbon nitride composite material prepared by the present invention. Specific Embodiments

[0019] The technical solutions of the present invention will be further described in detail in conjunction with the following specific embodiments. The present invention includes but is not limited to the following embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] Example 1:

[0021] After mixing 0.63 g of melamine with 3.65 g of aqueous formaldehyde solution (37%), it was dissolved in 65 mL of deionized water. After stirring well for 30 min under the condition of a 50 °C water bath, 0.15 g of copper(II) acetate monohydrate (Cu(CH₃COO)₂·H₂O) was added, and stirring continued for 30 min. Then it was transferred into a hydrothermal autoclave and hydrothermally treated at 150 °C for 20 h. The solid product was centrifugally washed with water and ethanol and dried at 60 °C. The obtained sample was heat-treated at high temperature in a nitrogen atmosphere with continuous flow (60 mL / min) in a tube furnace. It was heated to 500 °C at a heating rate of 5 °C / min and held at a constant temperature for 3 h. The obtained sample was ground and collected to obtain a copper / carbon nitride composite material (the mass percentage of copper was 15%).

[0022] Example 2:

[0023] After mixing 0.63 g of melamine with 3.65 g of aqueous formaldehyde solution (37%), it was dissolved in 65 mL of deionized water. After stirring well for 30 min under the condition of a 50 °C water bath, 0.10 g of copper(II) chloride (CuCl₂) was added, and stirring continued for 30 min. Then it was transferred into a hydrothermal autoclave and hydrothermally treated at 150 °C for 20 h. The solid product was centrifugally washed with water and ethanol and dried at 60 °C. The obtained sample was heat-treated at high temperature in a nitrogen atmosphere with continuous flow (60 mL / min) in a tube furnace. It was heated to 500 °C at a heating rate of 5 °C / min and held at a constant temperature for 3 h. The obtained sample was ground and collected to obtain a copper / carbon nitride composite material (the mass percentage of copper was 15%).

[0024] Example 3:

[0025] After mixing 0.63 g of melamine with 3.65 g of aqueous formaldehyde solution (37%), it was dissolved in 65 mL of deionized water. After stirring well for 30 min under the condition of a 50 °C water bath, 0.15 g of copper(II) acetate monohydrate (Cu(CH₃COO)₂·H₂O) and 0.18 g of cobalt(II) acetate tetrahydrate (Co(CH₃COO)₂·4H₂O) were added, and stirring continued for 30 min. Then it was transferred into a hydrothermal autoclave and hydrothermally treated at 150 °C for 20 h. The solid product was centrifugally washed with water and ethanol and dried at 60 °C. The obtained sample was heat-treated at high temperature in a nitrogen atmosphere with continuous flow (90 mL / min) in a tube furnace. It was heated to 500 °C at a heating rate of 5 °C / min and held at a constant temperature for 3 h. The obtained sample was ground and collected to obtain a copper / carbon nitride composite material (the mass percentage of copper was 15%, and the doping amount of cobalt accounted for 0.3% of the mass percentage of copper).

[0026] Example 4:

[0027] After mixing 0.63 g of melamine with 3.65 g of aqueous formaldehyde solution (37%), it was dissolved in 65 mL of deionized water. After stirring well for 30 min under the condition of a 50 °C water bath, 0.15 g of copper acetate monohydrate (Cu(CH3COO)2·H2O) and 0.12 g of cobalt acetate tetrahydrate (Co(CH3COO)2·4H2O) were added, and stirring continued for 30 min. Then it was transferred into a hydrothermal autoclave and hydrothermally treated at 150 °C for 20 h. The solid product was centrifugally washed with water and ethanol and dried at 60 °C. The obtained sample was heat-treated at high temperature in a tubular furnace under a continuously flowing (120 mL / min) argon atmosphere. It was heated to 500 °C at a heating rate of 5 °C / min and held at a constant temperature for 5 h. The obtained sample was ground and collected to obtain a copper / carbon nitride composite material (the mass percentage of copper was 18%, and the doping amount of cobalt accounted for 0.25% of the mass of copper).

[0028] Example 5:

[0029] After mixing 0.63 g of melamine with 3.65 g of aqueous formaldehyde solution (37%), it was dissolved in 65 mL of deionized water. After stirring well for 30 min under the condition of a 50 °C water bath, 0.15 g of copper acetate monohydrate (Cu(CH3COO)2·H2O) and 0.24 g of cobalt acetate tetrahydrate (Co(CH3COO)2·4H2O) were added, and stirring continued for 30 min. Then it was transferred into a hydrothermal autoclave and hydrothermally treated at 150 °C for 20 h. The solid product was centrifugally washed with water and ethanol and dried at 60 °C. The obtained sample was heat-treated at high temperature in a tubular furnace under a continuously flowing (90 mL / min) nitrogen atmosphere. It was heated to 500 °C at a heating rate of 5 °C / min and held at a constant temperature for 8 h. The obtained sample was ground and collected to obtain a copper / carbon nitride composite material (the mass percentage of copper was 20%, and the doping amount of cobalt was 0.4% of the mass of copper).

[0030] Example 6:

[0031] After mixing 0.63 g of melamine with 3.65 g of aqueous formaldehyde solution (37%), it was dissolved in 65 mL of deionized water. After stirring well for 30 min under the condition of a 50 °C water bath, 0.15 g of copper acetate monohydrate (Cu(CH3COO)2·H2O) and 0.18 g of cobalt acetate tetrahydrate (Co(CH3COO)2·4H2O) were added, and stirring continued for 30 min. Then it was transferred into a hydrothermal autoclave and hydrothermally treated at 150 °C for 20 h. The solid product was centrifugally washed with water and ethanol and dried at 60 °C. The obtained sample was heat-treated at high temperature in a tubular furnace under a continuously flowing (90 mL / min) nitrogen atmosphere. It was heated to 600 °C at a heating rate of 5 °C / min and held at a constant temperature for 5 h. The obtained sample was ground and collected to obtain a copper / carbon nitride composite material (the mass percentage of copper was 40%, and the doping amount of cobalt accounted for 0.3% of the mass of copper).

[0032] Example 7:

[0033] After mixing 0.63 g of melamine with 3.65 g of aqueous formaldehyde solution (37%), it was dissolved in 65 mL of deionized water. After stirring well for 30 min under the condition of a 50 °C water bath, 0.15 g of copper(II) acetate monohydrate (Cu(CH₃COO)₂·H₂O) and 0.18 g of cobalt(II) acetate tetrahydrate (Co(CH₃COO)₂·4H₂O) were added, and stirring was continued for 30 min. Then it was transferred into a hydrothermal autoclave and hydrothermally treated at 150 °C for 20 h. The solid product was centrifugally washed with water and ethanol and dried at 60 °C. The obtained sample was heat-treated at high temperature in a tube furnace under a continuously flowing (90 mL / min) nitrogen atmosphere. It was heated to 800 °C at a heating rate of 5 °C / min and held at a constant temperature for 5 h. The obtained sample was ground and collected to obtain a copper / carbon nitride composite material (the mass percentage of copper was 50%, and the doping amount of cobalt accounted for 0.3% of the mass percentage of copper).

[0034] Example 8:

[0035] After mixing 0.63 g of melamine with 3.65 g of aqueous formaldehyde solution (37%), it was dissolved in 65 mL of deionized water. After stirring well for 30 min under the condition of a 50 °C water bath, 0.15 g of copper(II) acetate monohydrate (Cu(CH₃COO)₂·H₂O) and 0.18 g of nickel(II) acetate tetrahydrate (Ni(CH₃COO)₂·4H₂O) were added, and stirring was continued for 30 min. Then it was transferred into a hydrothermal autoclave and hydrothermally treated at 150 °C for 20 h. The solid product was centrifugally washed with water and ethanol and dried at 60 °C. The obtained sample was heat-treated at high temperature in a tube furnace under a continuously flowing (90 mL / min) nitrogen atmosphere. It was heated to 600 °C at a heating rate of 5 °C / min and held at a constant temperature for 5 h. The obtained sample was ground and collected to obtain a copper / carbon nitride composite material (the mass percentage of copper was 40%, and the doping amount of nickel accounted for 0.3% of the mass percentage of copper).

[0036] Example 9:

[0037] After mixing 0.63 g of melamine with 3.65 g of aqueous formaldehyde solution (37%), it was dissolved in 65 mL of deionized water. After stirring well for 30 min under the condition of a 50 °C water bath, 0.15 g of copper(II) acetate monohydrate (Cu(CH₃COO)₂·H₂O) and 0.21 g of ferrous sulfate heptahydrate (FeSO₄·7H₂O) were added, and stirring was continued for 30 min. Then it was transferred into a hydrothermal autoclave and hydrothermally treated at 150 °C for 20 h. The solid product was centrifugally washed with water and ethanol and dried at 60 °C. The obtained sample was heat-treated at high temperature in a tube furnace under a continuously flowing (90 mL / min) nitrogen atmosphere. It was heated to 600 °C at a heating rate of 5 °C / min and held at a constant temperature for 5 h. The obtained sample was ground and collected to obtain a copper / carbon nitride composite material (the mass percentage of copper was 40%, and the doping amount of iron accounted for 0.3% of the mass percentage of copper).

[0038] Example 10:

[0039] After mixing 0.63 g of melamine with 3.65 g of aqueous formaldehyde solution (37%), it was dissolved in 65 mL of deionized water. After stirring well for 30 min under the condition of a 50 °C water bath, 0.15 g of copper(II) acetate monohydrate (Cu(CH3COO)2·H2O) and 0.21 g of zinc nitrate hexahydrate (ZnNO3·6H2O) were added, and stirring was continued for 30 min. Then it was transferred into a hydrothermal autoclave and hydrothermally treated at 150 °C for 20 h. The solid product was centrifugally washed with water and ethanol and dried at 60 °C. The obtained sample was heat-treated at high temperature in a nitrogen atmosphere flowing continuously (90 mL / min) in a tubular furnace. It was heated to 600 °C at a heating rate of 5 °C / min and held at a constant temperature for 5 h. The obtained sample was ground and collected to obtain a copper / carbon nitride composite material (the mass percentage of copper was 40%, and the doping amount of zinc accounted for 0.3% of the mass percentage of copper).

[0040] Example 11:

[0041] The copper / carbon nitride composite material prepared in Example 6 was used as a catalyst for the photocatalytic water splitting hydrogen production reaction. The photocatalytic reaction system included 20 mL of a 10% (volume fraction) triethanolamine solution, 20 mg of eosin Y, and 3 mg of the catalyst. After the reaction mixture was ultrasonically treated for 5 min, it was transferred into a photocatalytic reaction tube, and nitrogen was introduced to remove the air in the tube. Using a 300 W xenon lamp as the light source (>420 nm) for irradiation, the photocatalytic reaction was carried out for three hours. The gas-phase products were detected by gas chromatography, and the hydrogen generation rate could reach 12.38 mmol / (g·h). Using the corresponding polymer microsphere precursor as the catalyst for the photocatalytic water reaction under the same conditions, the hydrogen generation rate was only 3.59 mmol / (g·h).

Claims

1. A polymer microsphere-assisted copper / carbon nitride composite material, its preparation method and application, characterized in that, The copper / carbon nitride composite material is a composite material with copper nanoparticles supported on a carbon nitride matrix. Among them, the carbon nitride matrix is an amorphous structure, the mass percentage content of copper is 15% - 50%, and the composite material is spherical particles with a size of 500 - 1000 nm. Its preparation method includes the following steps: Mix melamine, aqueous formaldehyde solution and a certain amount of copper metal precursor salt (or multiple metal precursor salts), where the molar amount of the metal precursor salt is 10% - 20% of that of melamine. The mixture is hydrothermally synthesized to obtain a polymer microsphere precursor containing copper nanoparticles. The precursor is placed in an inert atmosphere, heated to a certain temperature at a rate of 5 °C / min and then kept at a constant temperature for a period of time, and then cooled naturally and ground to obtain a powder product, which is the polymer microsphere-assisted copper / carbon nitride composite material.

2. A polymer microsphere-assisted copper / carbon nitride composite material, its preparation method and application according to claim 1, characterized in that, During the heating treatment of the polymer microsphere precursor, the constant temperature is 500 - 800 °C, and the constant temperature treatment time is 3 - 8 hours.

3. A polymer microsphere-assisted copper / carbon nitride composite material, its preparation method and application according to claim 1, characterized in that, The inert atmosphere is continuously flowing nitrogen or argon, and the gas flow rate is 60 - 120 mL / min.

4. A polymer microsphere-assisted copper / carbon nitride composite material, its preparation method and application according to claim 1, characterized in that, The high-temperature treatment reduces the particle size of the polymer microsphere precursor, resulting in more copper nanoparticles being exposed on the surface of the microspheres.

5. A polymer microsphere-assisted copper / carbon nitride composite material, its preparation method and application according to claim 1, characterized in that, The copper / carbon nitride composite material is a single-metal copper / carbon nitride composite material or a multi-metal doped copper / carbon nitride composite material, and the metal doping amount accounts for 0.25% - 0.4% of the mass of copper.

6. The multi-metal doped copper / carbon nitride composite material according to claim 5, wherein The doped metal includes at least one of cobalt, nickel, iron, and zinc, and the copper metal and the multi-metal precursor salt are at least one of nitrate, acetate, chloride, and sulfate.

7. A polymer microsphere-assisted copper / carbon nitride composite material, its preparation method and application according to claim 1, characterized in that, In the copper / carbon nitride composite material, the copper nanoparticles are mainly in the zero-valent state, and a small amount of divalent copper coexists.

8. A polymer microsphere-assisted copper / carbon nitride composite material, its preparation method and application according to claim 1, characterized in that, The copper / carbon nitride composite material has excellent hydrogen production activity when applied to the photocatalytic water reaction.

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