A plasmon resonance-enhanced polishing method for online synthesis of heterogeneous photocatalysts

Abstract

The present invention discloses a plasmon resonance enhanced polishing method for online synthesis of multiphase photocatalysts, which belongs to the field of ultra-precision machining and comprises the following steps: selecting nanoparticles with photocatalytic properties as photocatalysts; selecting metal salts as precursors and preparing a metal salt solution, and mixing the photocatalysts into the metal salt solution to form a polishing liquid; irradiating visible catalytic light to the area where the polishing liquid contacts a workpiece, wherein the precursors increase the interface photocatalytic reaction rate under the induction of the light source, and simultaneously precipitate metal nanoparticles online to enhance the interface photocatalytic reaction and achieve a significant improvement in the material removal rate; the present invention consumes the narrow-bandgap visible photocatalyst conduction band electrons through the reduction reaction of the precursors, thereby avoiding the recombination of photogenerated carriers and improving the photocatalytic reaction rate; and simultaneously enhances the photocatalytic reaction rate synergistically through surface plasmon-enhanced light scattering and injection of hot electrons from metal nanoparticles into the conduction band of the photocatalyst, thereby achieving a significant improvement in the material removal rate.

Description

Technical Field

[0001] The invention belongs to the field of ultra-precision machining, and in particular relates to a plasmon resonance enhanced polishing method for online synthesis of multiphase photocatalysts. Background Art

[0002] Major national demands in semiconductor manufacturing, aerospace, biomedicine, and ultra-precision instrumentation are driving the innovative development of manufacturing technologies, placing ever-higher demands on the surface processing quality and material removal rates of hard and brittle semiconductor materials. For example, synchrotron radiation source X-ray reflectors, manufactured by grinding and polishing single-crystal silicon, require surface accuracy down to the atomic level. Efficient atomic-scale manufacturing of novel semiconductor substrates such as diamond, silicon carbide, and gallium nitride is a necessary step in the development of high-power and even quantum devices.

[0003] For ultra-precision machining of hard and brittle materials, traditional machining methods include chemical mechanical polishing, in which acid and alkaline oxidants in the polishing liquid form an oxide layer on the surface of the workpiece, which is then removed by hard abrasives, causing a certain degree of scratches on the surface. In order to achieve manufacturing at a smaller scale, a series of machining methods have been proposed. For example, colloidal jet polishing technology is used to adapt to a variety of hardness materials, but in actual applications, problems such as particle dispersion and particle size control need to be solved. Magneto-rheological finishing of the workpiece is achieved by using a strong magnetic field to control the magnetic fluid in contact with the workpiece, but in actual machining, the control accuracy is difficult to guarantee and the equipment is expensive.

[0004] Some scholars have proposed photocatalytic-assisted polishing. This method mainly relies on abrasives with photocatalytic properties in the ultraviolet band, such as TiO2, ZnO, SnO2, etc. Under the catalytic action of ultraviolet light, strong oxidants such as hydrogen peroxide or potassium permanganate are used to form an oxide layer on the surface of the workpiece to be processed, and then the oxide layer is removed by mechanical action. Existing PACMP technology still faces many challenges: First, mainstream photocatalysts (such as TiO2 and ZnO) only respond to ultraviolet light (wavelength <400 nm, accounting for only 4% of the solar spectrum), requiring a high-energy ultraviolet light source, which greatly limits energy utilization efficiency. In addition, ultraviolet radiation will accelerate the aging of the polishing pad; second, the catalyst is mostly synthesized offline and then added to the polishing liquid. Its agglomeration and sedimentation and poor interface contact result in low utilization of photogenerated charges. In addition, the catalyst synthesis process is complex and the synthesis cost is relatively high compared to the entire polishing process; third, the electron-hole recombination rate in the photocatalytic process is fast (nanosecond level), which seriously restricts the effective implementation of the surface redox reaction. Therefore, the development of a photocatalytic system that has visible light response, high stability and can be synthesized online during the polishing process has become the key to breaking through the bottleneck of photocatalytic-assisted polishing technology. Summary of the Invention

[0005] The purpose of the present invention is to provide a plasmon resonance enhanced polishing method for online synthesis of multiphase photocatalysts, so as to solve the problems in existing photocatalytic polishing methods, such as cumbersome and complicated synthesis process, single catalytic light source band, and high recombination rate of photogenerated carriers of narrow-bandgap catalysts resulting in low material removal rate.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0007] The present invention relates to a plasmon resonance enhanced polishing method for online synthesis of multiphase photocatalysts, which comprises the following steps:

[0008] S1. Selecting narrow-bandgap nanoparticles with photocatalytic properties as photocatalytic media;

[0009] S2. Selecting a metal salt as a precursor for the interfacial photocatalytic reaction and configuring a metal salt solution, and mixing the photocatalyst into the metal salt solution to form a polishing solution, and placing the workpiece in the polishing solution;

[0010] S3. Selecting a broad-spectrum light source as a visible catalytic light source to irradiate the area where the polishing liquid and the workpiece are in contact. During the polishing process, the metal ions in the precursor are reduced to elemental metal under the action of the visible catalytic light irradiation, agglomerated into metal nanoparticles, and then attached to the surface of the photocatalyst. Under the visible catalytic light irradiation, the metal nanoparticles induce a surface plasmon effect, promote the photochemical reaction at the interface between the photocatalyst and the workpiece, and induce the formation of interfacial bridge bonds;

[0011] S4. Promote the flow of polishing liquid and drive the flow of catalytic medium, thereby achieving atomic-level removal of the workpiece surface.

[0012] Preferably, in S1, the photocatalyst is hydrothermally treated by a hydrothermal method to terminate the hydroxyl group on the surface of the photocatalyst, specifically by transferring the mixed photocatalyst powder and deionized water into a high-pressure reactor, and heating the mixture in an electric oven at 80-300°C for 2-20 hours, then washing the mixture with deionized water, and finally drying the mixture at 80°C for 12 hours.

[0013] Preferably, in S1, the photocatalyst is any one of g-C3N4, SrTiO3, WO3, and CuO nanoparticles that respond to visible catalytic light, and the particle size of the photocatalyst is 10 to 1000 nm.

[0014] Preferably, in S2, the precursor is any one of silver nitrate, chloroplatinic acid, gold chloride, and aluminum sulfate.

[0015] Preferably, in the polishing liquid configured in S2, the concentration of the photocatalyst is 0.1-10 g / L, and the concentration of the precursor is 0.01-1 g / L.

[0016] Preferably, the wavelength range of the visible catalytic light in S3 is 400-800 nm, and the power range is 0.5-500 W.

[0017] Preferably, the metal salt solution in S2 is an aqueous solution, and in S3, the precursor also participates in the photocatalytic reduction reaction under the irradiation of the catalytic light source, consumes the photogenerated electrons in the conduction band of the photocatalyst, and causes the photogenerated holes in the valence band to migrate to the catalyst surface, participate in the oxidation reaction of water, and generate hydroxyl free radicals that are adsorbed on the catalyst surface.

[0018] Preferably, the particle size of the metal nanoparticles agglomerated in S3 is 5 to 300 nm.

[0019] Preferably, in said S3, when the photon frequency of the incident visible catalytic light is consistent with the internal electron vibration frequency of the metal nanoparticles, it causes coupled oscillation of the electrons, thereby inducing a surface plasmon effect, enhancing the scattering of the visible catalytic light to increase the effective light absorption intensity of the photocatalyst, and at the same time promoting the injection of free electrons in the metal nanoparticles into the conduction band of the photocatalyst, synergistically improving the photocatalytic reaction rate, and further promoting the bonding between the photocatalyst and the workpiece interface.

[0020] Preferably, in S3, quantitative control of the photoreduction reaction of the precursor is achieved by regulating the concentration of the precursor, the intensity of the catalytic light source, and the wavelength of the visible catalytic light, thereby controlling the reduction rate of the metal element and the agglomeration particle size of the metal nanoparticles to regulate the intensity of the plasmon effect, and ultimately achieving controllable material removal with a single atomic layer precision on the workpiece.

[0021] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0022] 1. The present invention relates to a plasmon resonance enhanced polishing method for online synthesis of multiphase photocatalysts, in which nanoparticles with photocatalytic properties are used as photocatalysts, and metal salts are used as precursors of interfacial photocatalytic reactions to mix with the photocatalysts to prepare a polishing liquid. Under the irradiation of visible catalytic light, the metal ions in the precursor participate in a reduction reaction, and metal nanoparticles with plasmon effects within the range of visible catalytic light are formed online on the surface of the photocatalyst. The metal nanoparticles enhance the scattering of visible catalytic light to increase the effective light absorption intensity of the photocatalyst. At the same time, the free electrons in the metal nanoparticles are excited and injected into the conduction band of the photocatalyst, thereby synergistically increasing the photocatalytic reaction rate and achieving a significant improvement in the material removal rate.

[0023] 2. The plasmon resonance enhanced polishing method for online synthesis of multiphase photocatalysts involved in the present invention selects metal salts as precursors for interfacial photocatalytic reactions and prepares a metal salt solution, which is then mixed with nanoparticles having photocatalytic properties in a certain proportion to prepare a polishing liquid. Visible catalytic light is irradiated to the area in contact with the polishing liquid and the workpiece. The precursor participates in a photocatalytic reduction reaction to consume photogenerated electrons in the conduction band of the photocatalyst, and the photogenerated holes in the valence band are able to migrate to the surface of the catalytic medium and participate in the oxidation reaction of water, thereby generating more hydroxyl free radicals that are adsorbed on the surface of the catalytic medium, avoiding the recombination of photogenerated carriers to increase the photocatalytic reaction rate.

[0024] 3. The plasmon resonance enhanced polishing method for online synthesis of multiphase photocatalysts involved in the present invention selects nanoparticles with visible light catalytic activity as photocatalysts, and hydrothermally treats the photocatalysts to graft hydroxyl groups on their surfaces, thereby improving the photocatalytic activity of the photocatalyst body and achieving a significant increase in the material removal rate during the processing process.

[0025] 4. The plasmon resonance enhanced polishing method for online synthesis of multiphase photocatalysts involved in the present invention can achieve quantitative control of the photoreduction reaction of the precursor by regulating the concentration of the precursor, the intensity of the visible catalytic light, and the wavelength of the visible catalytic light, while controlling the rate and particle size of the metal element precipitation to regulate the intensity of the surface plasmon effect, thereby achieving controllable material removal with a single atomic layer precision of the workpiece to be processed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the process of the plasmon resonance enhanced polishing method for online synthesis of heterogeneous photocatalysts;

[0027] Figure 2 Schematic diagram of the plasmon resonance-enhanced polishing method for the online synthesis of heterogeneous photocatalysts. DETAILED DESCRIPTION

[0028] The technical solutions of the present invention are further described in detail below through specific embodiments. The embodiments are provided for the purpose of illustrating the present invention and are not intended to limit the present invention. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in this application without creative work are within the scope of protection of this application.

[0029] The present invention relates to a plasmon resonance enhanced polishing method for online synthesis of multiphase photocatalysts, which comprises the following steps:

[0030] S1. Select nanoparticles with photocatalytic properties as photocatalysts and perform hydrothermal treatment on the photocatalysts to terminate their surfaces with hydroxyl groups. The specific method of hydrothermal treatment is as follows: transfer the photocatalyst powder and deionized water into an autoclave, heat it in an electric oven at 80-300°C for 2-20 hours, then wash the photocatalyst with deionized water, and finally dry it at 80°C for 12 hours. The above-mentioned photocatalyst is a photocatalyst that responds to visible light, such as g-C3N4, SrTiO3, WO3, and CuO, with a particle size of 10-1000 nm.

[0031] S2. Select a metal salt as a precursor for the interfacial photocatalytic reaction and prepare a metal salt solution, and mix the photocatalyst into the metal salt solution to form a polishing liquid, and place the workpiece in the polishing liquid; the precursor is a metal salt that is easily reduced, such as silver nitrate, chloroplatinic acid, gold chloride, aluminum sulfate, etc., and the metal salt solution is an aqueous solution; the concentration of the photocatalyst in the prepared polishing liquid is 0.1~10g / L, and the concentration of the precursor is 0.01~1g / L.

[0032] S3. Select a broad spectrum light source as the visible catalytic light, with a wavelength range of 400-800nm ​​and a power range of 0.5-500W. Figure 1 As shown, visible catalytic light is irradiated to the area where the polishing liquid contacts the workpiece, and the precursor participates in the photocatalytic reduction reaction to consume the photogenerated electrons e in the conduction band of the photocatalyst. - , so that the valence band photogenerated holes h + Gain Energy E g Afterwards, they migrate to the surface of the photocatalyst and participate in the water oxidation reaction, thereby generating more hydroxyl radicals that adsorb onto the surface of the catalytic medium, increasing the photocatalytic reaction rate on the workpiece surface and thus improving the material removal rate. Simultaneously, under the irradiation of visible catalytic light, the metal ions in the precursor are reduced to metal elements, agglomerated into metal nanoparticles ranging from 5 to 300 nm. These metal nanoparticles then precipitate and adhere to the surface of the photocatalyst, inducing a surface plasmon effect under the irradiation of visible catalytic light, significantly improving the material removal rate. Simultaneously, by regulating the concentration of the precursor, the intensity of the visible catalytic light, and the wavelength of the visible catalytic light, quantitative control of the precursor's photoreduction reaction is achieved. Simultaneously, the rate and particle size of the metal element precipitation are controlled to regulate the intensity of the plasmon effect, thereby achieving controllable material removal with a single atomic layer of precision on the workpiece.

[0033] The specific principle of step 3 is as follows Figure 2As shown in the figure, when the frequency of the incident visible catalytic light photons is consistent with the vibration frequency of the electrons inside the metal nanoparticles, it will cause the electrons to oscillate in a coupled manner, thereby inducing the surface plasmon effect. A beam of electromagnetic waves with a frequency close to the resonance frequency is radiated along the surface of the metal nanoparticles, enhancing the scattering of the visible catalytic light to increase the effective light absorption intensity of the photocatalyst. At the same time, when the free electrons e in the metal nanoparticles - When the absorbed photon energy is greater than its work function, it will be excited to jump to the surface of the metal particles to form hot electrons, which are then injected into the conduction band of the photocatalyst and react with water molecules to form superoxide radicals O2 - A large number of hydroxyl radicals -OH are then formed and adsorbed on the surface of the photocatalyst, increasing the rate of the interfacial photocatalytic reaction, thereby inducing and promoting the bonding between the catalyst and the workpiece interface, thereby achieving a significant improvement in the material removal rate.

[0034] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A plasmon resonance enhanced polishing method for online synthesis of heterogeneous photocatalysts, characterized by: It includes the following steps: S1. Selecting nanoparticles with photocatalytic properties as photocatalysts; S2. Selecting a metal salt as a precursor for the interfacial photocatalytic reaction and configuring a metal salt solution, and mixing the photocatalyst into the metal salt solution to form a polishing solution, and placing the workpiece in the polishing solution; S3. Select a broad-spectrum light source as a visible catalytic light source to irradiate the area where the polishing liquid and the workpiece are in contact. Under the action of the visible catalytic light, the metal ions in the precursor are reduced to elemental metals and agglomerated into metal nanoparticles, which then adhere to the surface of the photocatalyst. Under the visible catalytic light irradiation, the metal nanoparticles induce a surface plasmon effect, promoting bonding between the photocatalyst and the workpiece interface. S4. Promote the flow of polishing liquid and drive the flow of catalytic medium, thereby achieving atomic-level removal of the workpiece surface.

2. The plasmon resonance enhanced polishing method for online synthesis of heterogeneous photocatalysts according to claim 1, characterized in that: In S1, the photocatalyst is hydrothermally treated by a hydrothermal method to terminate the hydroxyl groups on the surface of the photocatalyst. Specifically, the photocatalyst powder and deionized water are mixed and transferred to a high-pressure reactor, and heated in an electric oven at 80-300°C for 2-20 hours, then washed with deionized water, and finally dried at 80°C for 12 hours.

3. The plasmon resonance enhanced polishing method for online synthesis of heterogeneous photocatalysts according to claim 2, characterized in that: In S1, the photocatalyst is any one of g-C3N4, SrTiO3, WO3, and CuO nanoparticles that respond to visible catalytic light, and the particle size of the photocatalyst is 10 to 1000 nm.

4. The plasmon resonance enhanced polishing method for online synthesis of heterogeneous photocatalysts according to claim 1, characterized in that: In S2, the precursor is any one of silver nitrate, chloroplatinic acid, gold chloride, and aluminum sulfate.

5. The plasmon resonance enhanced polishing method for online synthesis of heterogeneous photocatalysts according to claim 4, characterized in that: In the polishing liquid configured in S2, the concentration of the photocatalyst is 0.1-10 g / L, and the concentration of the precursor is 0.01-1 g / L.

6. The plasmon resonance enhanced polishing method for online synthesis of heterogeneous photocatalysts according to claim 1, characterized in that: The wavelength range of the visible catalytic light in S3 is 400-800 nm, and the power range is 0.5-500 W.

7. The plasmon resonance enhanced polishing method for online synthesis of heterogeneous photocatalysts according to claim 1, characterized in that: The metal salt solution in S2 is an aqueous solution. In S3, the precursor also participates in the photocatalytic reduction reaction under the irradiation of the catalytic light source, consumes the photogenerated electrons in the conduction band of the photocatalyst, and causes the photogenerated holes in the valence band to migrate to the catalyst surface, participate in the oxidation reaction of water, and generate hydroxyl free radicals that are adsorbed on the catalyst surface.

8. The plasmon resonance enhanced polishing method for online synthesis of heterogeneous photocatalysts according to claim 1, characterized in that: The particle size of the metal nanoparticles agglomerated in S3 is 5-300 nm.

9. The plasmon resonance enhanced polishing method for online synthesis of heterogeneous photocatalysts according to claim 1, characterized in that: In S3, when the photon frequency of the incident visible catalytic light is consistent with the internal electron vibration frequency of the metal nanoparticles, it causes coupled oscillation of the electrons, thereby inducing the generation of a surface plasmon effect, enhancing the scattering of the visible catalytic light to increase the effective light absorption intensity of the photocatalyst, and at the same time promoting the injection of free electrons in the metal nanoparticles into the conduction band of the photocatalyst, synergistically improving the photocatalytic reaction rate, and further promoting the bonding between the photocatalyst and the workpiece interface.

10. The plasmon resonance enhanced polishing method for online synthesis of heterogeneous photocatalysts according to claim 1, characterized in that: In S3, quantitative control of the photoreduction reaction of the precursor is achieved by regulating the concentration of the precursor, the intensity of the catalytic light source, and the wavelength of the visible catalytic light, thereby controlling the reduction rate of the metal element and the agglomeration particle size of the metal nanoparticles to regulate the intensity of the plasmon effect, and ultimately achieving controllable material removal with a single atomic layer precision on the workpiece.

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