Method for generating reactive oxygen free radicals based on contact electrocatalysis of CdSe quantum dots and application of method

Abstract

The invention discloses a method for generating reactive oxygen free radicals based on contact electro-catalysis of CdSe quantum dots and application of the method, and belongs to the technical field of nano-catalysis. The method comprises the following steps: adding CdSe quantum dots into an H2O2 aqueous solution, mixing and reacting to generate an active oxygen free radical OH; the mechanism of the method disclosed by the invention is as follows: when water molecules are in contact with the CdSe quantum dots, electrons are lost to form water free radical cations (H2O < + >), and then the water free radical cations (H2O < + >) are rearranged to generate OH and H3O; meanwhile, electrons received by the surface of CdSe can also reduce H2O2, OH is further generated, and double-path catalytic circulation is formed. The method can be used for degrading organic pollutants (such as methylene blue), and has the remarkable advantages of mild conditions, high efficiency and environmental friendliness. The method can be widely applied to the fields of water treatment, disinfection and sterilization, biomedical free radical regulation and control and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanocatalysis, and particularly relates to a method for generating active oxygen free radicals based on contact electrocatalysis (CEC) of CdSe quantum dots and application thereof. BACKGROUND

[0002] As a highly reactive free radical, hydroxyl radical (·OH) is widely used in organic pollutant degradation, antibacterial treatment and tumor treatment. However, the existing ·OH generation path mostly depends on external excitation energy (such as light, voltage or heat energy), resulting in a complex process and high energy consumption. In recent years, the contact electrocatalysis (CEC) technology has emerged, which utilizes the interface contact-induced electron transfer to realize the interface redox reaction and generate ROS free radicals. Since the contact electrification effect exists in various materials, the selection range of catalysts is greatly broadened. CEC provides a new mechanism different from traditional catalysis, and its application prospect gradually appears in the fields of energy conversion, environmental protection, biomedicine and the like. However, as a new emerging catalysis strategy, the catalytic efficiency of CEC still has a great space for improvement. In the previous research, a new CEC catalysis strategy based on hydrogen peroxide (H2O2) was developed, which utilizes the H2O2 reduction path instead of the traditional CEC oxygen reduction path, and significantly improves the generation efficiency of ·OH. However, the current CEC research mainly focuses on perfluoropolymer materials or macroscopic interfaces, and the application of quantum dot materials in the CEC field has not been fully explored. Although the feasibility of CEC has been verified in the semiconductor particle system, systematic research on quantum dot systems is still less, especially there is no research on utilizing them to catalyze the H2O2 reduction path. SUMMARY

[0003] The application provides a method for generating active oxygen free radicals based on contact electrocatalysis of CdSe quantum dots and application thereof. By constructing a "solid-liquid" interface between CdSe quantum dots and aqueous solution, under the condition of no external electric field and room temperature, the interface contact electrification induces electron transfer, and ·OH free radicals are generated from water and H2O2. The specific mechanism includes: first, when water molecules (H2O) contact with CdSe quantum dots modified with mercaptopropionic acid, a built-in electric field is formed at the interface, which drives the electron transfer from H2O to CdSe quantum dots (CdSe ), and the residual H2O + · at the interface; then, H2O + · quickly undergoes proton transfer and bond breaking reaction to generate ·OH free radicals and hydronium ions (H3O + ); finally, the electron transfer to CdSe The electrons are then captured by H2O2, reduced to generate new •OH, and the CdSe quantum dots restore electrical neutrality, completing the catalytic cycle (as shown in Figure 1 The present application first discovers the ability of CdSe quantum dots to generate •OH in the CEC reaction. The present application will expand the new application of CdSe quantum dots in the field of environmental pollutant degradation, provide important scientific basis for developing new catalytic strategies, and has important theoretical and application value.

[0004] The object of the present application is achieved by the following technical solutions: A method for generating active oxygen free radicals by contact electrocatalysis based on CdSe quantum dots, comprising the following steps: adding CdSe quantum dots into an aqueous H2O2 solution to mix and react, to generate active oxygen free radicals •OH.

[0005] Further, the CdSe quantum dots are preferably mercaptopropionic acid ligand modified CdSe quantum dots. Mercaptopropionic acid is used to stabilize CdSe quantum dots, so that they can be stably stored in aqueous solution.

[0006] Further, the CdSe quantum dots are added into the catalytic reaction system composed of mixing H2O2 aqueous solution, and the concentration of CdSe quantum dots is preferably 2-10 mg / mL, and the concentration of H2O2 is preferably 100-900 mM.

[0007] Further, the reaction is preferably carried out under vortex or ultrasonic conditions, and the reaction temperature is preferably room temperature.

[0008] The method for generating active oxygen free radicals by contact electrocatalysis based on CdSe quantum dots is applied in the field of environmental pollutant degradation. The pollutants can react with active oxygen to be degraded, including methylene blue, terephthalic acid, etc.

[0009] A method for degrading environmental pollutants, comprising the following steps: adding CdSe quantum dots, H2O2 or a substance capable of generating H2O2 into water containing pollutants, and performing vortex or ultrasonic treatment. The substance capable of generating H2O2 includes enzymes capable of generating H2O2 (for example: glucose oxidase GOD), substances having enzyme-like (similar to enzymes capable of generating H2O2) activity (for example: nano-enzyme), etc.

[0010] Application of CdSe quantum dots and H2O2 or a substance capable of generating H2O2 in the field of environmental pollutant degradation or in the preparation of an environmental pollutant degradation agent.

[0011] An environmental pollutant degradation agent, comprising CdSe quantum dots, and H2O2 or a substance capable of generating H2O2.

[0012] The present application has the following beneficial effects: (1) A new active oxygen radical generation method is provided, and a new mechanism of CdSe quantum dots catalyzing water and H2O2 to generate •OH is found.

[0013] (2) The catalytic performance of CdSe quantum dots is stable, which is conducive to practical application.

[0014] (3) The application can be used for degradation of organic pollutants (such as methylene blue), and has the advantages of mild conditions, high efficiency and environmental friendliness. The application can be widely applied to the fields of water treatment, disinfection and sterilization, and biomedical free radical regulation.

[0015] (4) The application provides an important scientific basis for developing a new catalytic strategy, and has important theoretical and application values. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a mechanism diagram of the method for generating active oxygen radicals by contact electrocatalysis based on CdSe quantum dots of the application.

[0017] Figure 2 is a preparation flowchart of CdSe quantum dots.

[0018] Figure 3 is a transmission electron microscope image of CdSe quantum dots.

[0019] Figure 4 is a DMPO-•OH electron spin resonance spectrum diagram of CdSe quantum dots-H2O and CdSe quantum dots-H2O2 respectively treated by vortex (a) or ultrasonic (b).

[0020] Figure 5 is an ultraviolet-visible absorption spectrum of methylene blue treated by CdSe quantum dots-H2O and CdSe quantum dots-H2O2, and figure a is a vortex treatment, and figure b is an ultrasonic treatment. DETAILED DESCRIPTION

[0021] The application will be further described below through the following non-limiting examples, and it should be understood that the examples are only some preferred technical solutions of the application, and the protection scope of the application is not limited to the examples.

[0022] Example 1 Preparation and characterization of CdSe quantum dots Preparation method: the preparation flowchart of CdSe quantum dots is as follows Figure 2As shown, specifically comprising the following steps: a three-necked flask was added with CdO 45 mg (0.35 mmol), oleic acid (1 mL) and octadecene (6 mL). The reaction was stirred at room temperature for 30 min under nitrogen flow, and then heated to 210°C until the CdO was completely dissolved. Then 5 mL of oleylamine was added, heated to 270°C, and a TOP-Se solution (3 mL, in which Se was 0.07 mmol / mL) was quickly injected, and the temperature was lowered to 250°C, and the reaction was carried out for 1 min. After the reaction was completed, it was immediately cooled, and the obtained CdSe core was purified by centrifugation and precipitation. After the synthesis of the oil-phase CdSe quantum dots, they were dispersed in 10 mL of n-hexane, 100 μL of the CdSe quantum dots were taken, 3 mL of n-hexane was added, and 8 μL of mercaptopropionic acid was stirred to react overnight to obtain the water-phase CdSe quantum dots for use in the following examples.

[0023] Characterization: The CdSe quantum dots prepared in this example were nanoparticles with a particle size of about 6.9 nm (TEM). Figure 3 ).

[0024] Example 2 Performance evaluation of CdSe quantum dots in catalyzing H2O2 to generate reactive oxygen free radicals The CdSe quantum dots (10 mg / mL) were added to an aqueous solution containing H2O2 (100 mM) and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO, 10 mM), or an aqueous solution containing DMPO (10 mM). Then the solution was treated by vortex (700 rpm) or ultrasound (30 kHz, 2.0 W / cm 2 ) for 20 min. The ESR spectrum of the mixed solution was determined by an electron paramagnetic resonance (ESR) spectrometer (Bruker magnettech ESR5000, Germany). The ESR test showed that the CdSe quantum dots could generate ·OH in the solution with or without H2O2, by vortex or ultrasound. Figure 4 And the amount of ·OH generated by the CdSe quantum dots catalyzing H2O2 was significantly increased compared with the amount of ·OH generated by catalyzing water alone.

[0025] Example 3 Degradation of environmental pollutants methylene blue (MB) by CdSe quantum dots The CdSe quantum dots were added to an aqueous solution containing H2O2 and MB, and after treatment by ultrasound or vortex, the UV-visible absorption spectrum of MB was recorded. The specific experimental process was as follows: CdSe quantum dots (10 mg / mL) were added to an aqueous solution containing H2O2 (100 mM) and MB (10 μg / mL), or an aqueous solution containing MB (10 μg / mL), and the total volume was 300 μL. The solution was treated by vortex (700 rpm) or ultrasound (30 kHz, 2.0 W / cm2 The solution was treated for 20 minutes. Finally, the absorbance change of MB was determined by UV-visible absorption spectrum. The results are shown in Figure 5 Under the treatment of vortex or ultrasonic for 20 min, MB was degraded due to the degradation of H2O2 and the generation of •OH, which caused the absorbance at 664 nm to decrease. Under the vortex treatment, the degradation rate of MB+CdSe QDs in aqueous solution was 5.77%, and the degradation rate of MB+CdSe QDs in H2O2 solution was 35.31%. Under the ultrasonic treatment, the degradation rate of MB+CdSe QDs in aqueous solution was 6.73%, and the degradation rate of MB+CdSe QDs in H2O2 solution was 45.10%. It is proved that the method for generating active oxygen free radicals based on the contact electrocatalysis (CEC) of CdSe quantum dots has the ability to degrade MB.

[0026] The above description is only the preferred embodiment of the present application, but the scope of protection of the present application is not limited to this. Any modification, equivalent replacement and improvement made by any person skilled in the art within the technical scope disclosed by the present application shall be included in the protection scope of the present application.

Claims

1. A method for generating reactive oxygen species based on CdSe quantum dots through contact electrocatalysis, characterized in that, Includes the following steps: CdSe quantum dots are added to an aqueous H2O2 solution and mixed to react, generating reactive oxygen free radicals •OH.

2. The method for generating reactive oxygen species based on CdSe quantum dots through contact electrocatalysis according to claim 1, characterized in that: The CdSe quantum dots mentioned are CdSe quantum dots modified with mercaptopropionic acid ligands.

3. The method for generating reactive oxygen species based on CdSe quantum dots through contact electrocatalysis according to claim 1, characterized in that: The catalytic reaction system, which is formed by adding CdSe quantum dots to an aqueous H2O2 solution, has a concentration of 2-10 mg / mL for the CdSe quantum dots.

4. The method for generating reactive oxygen species based on CdSe quantum dots through contact electrocatalysis according to claim 1, characterized in that: The catalytic reaction system is formed by adding CdSe quantum dots to an aqueous H2O2 solution, where the concentration of H2O2 is 100-900 mM.

5. The method for generating reactive oxygen species based on CdSe quantum dots through contact electrocatalysis according to claim 1, characterized in that: The reaction is carried out under vortex or ultrasonic conditions.

6. The application of the method for generating reactive oxygen species based on CdSe quantum dots through contact electrocatalysis according to any one of claims 1-5 in the field of environmental pollutant degradation, characterized in that: The pollutants described can be degraded by reacting with reactive oxygen species.

7. A method for degrading environmental pollutants, characterized in that, Includes the following steps: Add CdSe quantum dots, H2O2, or substances that can generate H2O2 to water containing pollutants, and then subject it to vortexing or ultrasonic treatment; the pollutants can react with reactive oxygen species to undergo degradation.

8. The application of CdSe quantum dots and H2O2 or substances capable of generating H2O2 in the field of environmental pollutant degradation, characterized by: The pollutants described can be degraded by reacting with reactive oxygen species.

9. The application of CdSe quantum dots and H2O2 or substances capable of generating H2O2 in the preparation of environmental pollutant degrading agents, characterized in that: The pollutants described can be degraded by reacting with reactive oxygen species.

10. An environmental pollutant degrading agent, characterized in that: It contains CdSe quantum dots, and H2O2 or substances that can produce H2O2.

Images