Preparation method of oxygen-containing vacancy CuO and application thereof

Abstract

The application belongs to the field of photocatalysis, and particularly relates to a preparation method of oxygen vacancy CuO and application thereof, and aims to solve the technical problems that the process of introducing oxygen vacancies into CuO is complex, and a large amount of energy is consumed. The oxygen vacancy CuO can be obtained by adding H2O2 into a Cu(CH3COO)2.H2O solution and performing a one-step simple normal-temperature reaction, the oxygen vacancy CuO can be used as a photocatalytic degradation material of organic matters, and organic pollutants tetracycline can be effectively degraded. The preparation method is simple and convenient to operate, and provides a new idea for introducing oxygen vacancies into materials.

Description

Technical Field

[0001] This invention belongs to the field of photocatalysis, specifically relating to a method for preparing oxygen-vacancy CuO and its application. Background Technology

[0002] In the field of photocatalysis, CuO is a very important photocatalytic semiconductor material. As a photocatalyst, it possesses many advantages, such as a narrow optical band gap allowing it to absorb a wide spectral range of sunlight, non-toxicity, and low raw material cost. However, precisely because of its narrow band gap, the recombination rate of photogenerated electrons and holes is high when used as a photocatalytic material, severely limiting the photocatalytic performance of pure CuO. This is why it is often used as a modifying material rather than a base material. To promote the separation of photogenerated carriers and enable it to exhibit certain photodegradation performance in the near-infrared region, modified CuO needs to be prepared.

[0003] Constructing oxygen vacancies in semiconductor materials is one of the important methods to improve their performance. Conventional methods for introducing oxygen vacancies mainly include chemical reduction, hydrogen heat treatment, plasma treatment, and ion doping. Patent CN112958089A discloses a method for preparing a copper oxide catalyst for catalyzing the degradation of pollutants in water by persulfate. The method involves dissolving Cu(NO3)2·6H2O and an organic carbon source in ultrapure water, followed by room temperature reaction, drying, and high-temperature calcination to obtain the copper oxide catalyst. Patent CN111644173A discloses a method for improving the photocatalytic activity of copper oxide. This method involves sequentially heating copper oxide at 750-850℃, immersing it in anhydrous ethanol, and then rapidly quenching it to prepare copper oxide with oxygen vacancies on its surface. Patent CN113502497A discloses a low-temperature plasma-modulated electrocatalyst and its preparation method and application. This method involves treating the surface of a copper-based catalyst using low-temperature plasma technology to introduce unsaturated active sites such as oxygen vacancies and hydroxyl functional groups onto its surface. While all of the above methods can introduce oxygen vacancies into materials, the preparation processes are complex and require significant energy consumption. Furthermore, in its natural state, CuO is a p-type semiconductor, making it difficult to convert copper vacancies into oxygen vacancies. Therefore, there is an urgent need to develop a simple process for introducing oxygen vacancies into the semiconductor material CuO. Summary of the Invention

[0004] To address the problems of low photocatalytic activity of CuO and the complex and energy-intensive processes required for introducing oxygen vacancies into CuO in existing technologies, this invention proposes a method for preparing oxygen-vacancy-containing CuO and its applications. Starting from the precursor, this invention employs a bottom-up approach to directly form oxygen-vacancy-containing CuO in one step, thereby broadening the absorption range of CuO, promoting the separation of photogenerated carriers, and ultimately improving the photocatalytic activity of CuO. Furthermore, the entire preparation process is simple and convenient to operate.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] Cu(CH3COO)2·H2O was dissolved in deionized water and stirred for 30 min. After stirring, the stirring speed was maintained at 800-1000 rpm, and H2O2 solution was slowly added dropwise to the Cu(CH3COO)2·H2O solution. The reaction was allowed to proceed at room temperature for 5-30 min, during which a black precipitate rapidly formed in the solution. After the reaction was complete, the black precipitate was centrifuged at 6000 rpm, and the supernatant was discarded. The precipitate was washed three times with deionized water, with the final wash using anhydrous ethanol. After washing, the precipitate was freeze-dried under vacuum. The resulting powder was oxygen-vacancy CuO.

[0007] Furthermore, the mass fraction of the H2O2 solution is 10%-30%.

[0008] Furthermore, the concentration of the Cu(CH3COO)2·H2O solution is 0.2-0.6 mol / L.

[0009] Furthermore, the volume ratio of H2O2 solution to Cu(CH3COO)2·H2O solution is 1:(0.5-2).

[0010] The oxygen-vacancy CuO prepared by the above preparation method.

[0011] The above-mentioned application of oxygen-vacancy CuO in the photocatalytic degradation of organic pollutants, wherein the organic pollutant is tetracycline.

[0012] The principle behind the formation of CuO and oxygen vacancies is as follows:

[0013] The chemical equation for the reaction can be represented as:

[0014] 2Cu(CH3COO)2+2H2O2→2CuO+4CH3COOH+O2

[0015] The specific principle is as follows: Since H₂O₂ is a polar solvent composed of two oxygen atoms and two hydrogen atoms, with oxygen atoms being more electronegative than hydrogen atoms, the molecule contains both positive and negative charges. This uneven charge distribution makes H₂O₂ polar, allowing it to combine with some copper ions to form black CuO. During the formation of CuO and the growth of CuO crystal nuclei, the reaction is very rapid. While some copper ions grow along with the crystal lattice to form CuO nanoparticles, they do not have time to combine with oxygen atoms. Consequently, some positions within the copper ions are left unfilled, resulting in CuO with oxygen vacancies.

[0016] The present invention has the following beneficial effects:

[0017] (1) Traditional methods for introducing oxygen vacancies into semiconductor materials typically include hydrogen reduction, high-energy particle bombardment, and ion doping. These methods are complex, require sophisticated experimental equipment, and are inconvenient to process. Most of these methods employ a top-down approach. This invention starts from the precursor and uses a bottom-up approach to directly form CuO containing oxygen vacancies in one step, thereby broadening the light absorption range of CuO, promoting the separation of photogenerated carriers, and improving the photocatalytic activity of CuO. Moreover, the preparation method is simple and easy to implement, the raw materials are inexpensive, and the cost is low.

[0018] (2) This invention provides a new strategy for preparing CuO containing oxygen vacancies. Due to the strong oxidizing properties of high-concentration H2O2, the chemical reaction is very fast, and black CuO precipitate is formed almost instantly in the solution. The formation of CuO crystal nuclei also occurs in a very short time. During the crystal lattice growth process, some copper ions do not combine with oxygen atoms, forming CuO with oxygen vacancies.

[0019] (3) The oxygen-vacancy CuO prepared by this invention has good photocatalytic degradation performance of organic matter. When the organic pollutant used is tetracycline, the adsorption efficiency (22.1%) and removal efficiency (59.3%) of the prepared oxygen-vacancy CuO are much higher than those of commercially available CuO. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 The XRD pattern of oxygen-vacancy CuO prepared in Example 1.

[0022] Figure 2 The Raman spectrum of oxygen-vacancy CuO prepared in Example 1.

[0023] Figure 3 The image shows the SEM pattern of the oxygen-vacancy CuO prepared in Example 1.

[0024] Figure 4 XPS spectrum of Cu 2p in oxygen-vacancy CuO prepared in Example 1.

[0025] Figure 5 XPS spectrum of O1s in oxygen-vacancy CuO prepared in Example 1.

[0026] Figure 6 EPR image of oxygen-vacancy CuO prepared in Example 1.

[0027] Figure 7 The UV-VIS-NIR spectrum of oxygen-vacancy CuO prepared in Example 1.

[0028] Figure 8 Photodegradation of tetracycline by oxygen-vacancy CuO prepared in Example 1 (a) and photodegradation cycle stability (b). Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] The preparation method of oxygen-vacancy CuO according to this embodiment includes the following steps:

[0032] 0.002 mol Cu(CH3COO)2·H2O was dissolved in 5 mL of deionized water and stirred for 30 min until completely dissolved, yielding a Cu(CH3COO)2·H2O solution. After stirring, the stirring speed was maintained at 800 rpm, and 5 mL of 15% H2O2 solution was slowly added dropwise to the Cu(CH3COO)2·H2O solution. A black precipitate rapidly formed in the solution, and the reaction was allowed to proceed at room temperature for 20 min. After the reaction was complete, the black precipitate was centrifuged at 6000 rpm, and the supernatant was discarded. The precipitate was washed three times with deionized water, with the final wash using anhydrous ethanol. After washing, the precipitate was freeze-dried under vacuum. The resulting powder was oxygen-vacancy CuO.

[0033] The crystal structure, morphology, elemental state, and light absorption properties of the oxygen-vacancy CuO prepared in this embodiment were tested and analyzed.

[0034] XRD analysis was performed on CuO containing oxygen vacancies, and the results are as follows: Figure 1 As shown. By Figure 1 It can be seen that three XRD characteristic peaks of CuO were found at 32.6°, 35.7° and 38.7°, corresponding to the (110) and (20) saturation values ​​of CuO, respectively. The (111) crystal plane corresponds to JCPDS card number 48-1548. This indicates that the prepared CuO sample is a monoclinic crystal system.

[0035] The space group of CuO in the monoclinic crystal system is C6, where each unit cell consists of two molecules and has 12 vibrational modes, as shown in Equation 1:

[0036] Г=4A u +5B u +A g +2B g Formula 1

[0037] Raman spectroscopy was performed on CuO containing oxygen vacancies, and the results are as follows: Figure 2 As shown in the figure, three distinct peaks can be observed in the Raman curve of CuO, located at 278 cm⁻¹. -1 324cm -1 and 618cm -1 At these locations, they respectively correspond to the A of CuO. g and 2 Bs g Vibration modes, where A g The characteristic peak intensity of the mode is significantly stronger than that of the two Bs. g The characteristic peaks indicate that the obtained CuO has certain defects.

[0038] Surface morphology analysis of CuO containing oxygen vacancies was performed, and the results are as follows: Figure 3 As shown, the prepared CuO is composed of a large number of nanostructures.

[0039] XPS high-resolution spectra of Cu 2p and O 1s in CuO containing oxygen vacancies were analyzed, and the results are as follows: Figure 4 and Figure 5 As shown. Figure 4 The XPS high-resolution spectrum of the Cu 2p orbital of CuO, after fitting and peak separation, shows that the fitted curve contains Cu 2p orbitals. 1 / 2 and Cu 2p 3 / 2 The two main peaks and their satellite peaks show that the difference in binding energy between the two main peaks is 19.91 eV, indicating that the Cu ion is in the +2 valence state. Figure 5 The XPS high-resolution spectrum of CuO O 1s orbital was obtained. After curve fitting, peaks of oxygen vacancies and lattice oxygen were observed, and the peak area of ​​oxygen vacancies was significantly larger than that of lattice oxygen, indicating that the prepared CuO contained a large number of oxygen vacancies.

[0040] To further confirm the presence of oxygen vacancies in CuO, the CuO prepared in this example was subjected to EPR testing under low-temperature conditions. The results are as follows: Figure 6As shown, through the direct conversion between the magnetic field and the g-factor, a significant signal exists at a g-factor of 2.003, which is usually considered to be the signal of oxygen vacancies, indicating that oxygen vacancies do indeed exist in CuO, thus verifying the XPS results.

[0041] The UV-Vis-IR absorption spectrometry of CuO containing oxygen vacancies was performed, and the results are as follows: Figure 7 As shown, it can be observed that it still exhibits strong light absorption in the near-infrared region.

[0042] Example 2

[0043] The preparation method of oxygen-vacancy CuO according to this embodiment includes the following steps:

[0044] 0.002 mol Cu(CH3COO)2·H2O was dissolved in 5 mL of deionized water and stirred for 30 min until completely dissolved, yielding a Cu(CH3COO)2·H2O solution. After stirring, the stirring speed was maintained at 800 rpm, and 5 mL of 10% H2O2 solution was slowly added dropwise to the Cu(CH3COO)2·H2O solution. A black precipitate rapidly formed in the solution, and the reaction was allowed to proceed at room temperature for 30 min. After the reaction was complete, the black precipitate was centrifuged at 6000 rpm, and the supernatant was discarded. The precipitate was washed three times with deionized water, with the final wash using anhydrous ethanol. After washing, the precipitate was freeze-dried under vacuum. The resulting powder was oxygen-vacancy CuO.

[0045] Example 3

[0046] The preparation method of oxygen-vacancy CuO according to this embodiment includes the following steps:

[0047] 0.002 mol Cu(CH3COO)2·H2O was dissolved in 5 mL of deionized water and stirred for 30 min until completely dissolved, yielding a Cu(CH3COO)2·H2O solution. After stirring, the stirring speed was maintained at 800 rpm, and 5 mL of 20% (w / w) H2O2 solution was slowly added dropwise to the Cu(CH3COO)2·H2O solution. A black precipitate rapidly formed in the solution, and the reaction was allowed to proceed at room temperature for 15 min. After the reaction was complete, the black precipitate was centrifuged at 6000 rpm, and the supernatant was discarded. The precipitate was washed three times with deionized water, with the final wash using anhydrous ethanol. After washing, the precipitate was freeze-dried under vacuum. The resulting powder was oxygen-vacancy CuO.

[0048] Example 4

[0049] The preparation method of oxygen-vacancy CuO according to this embodiment includes the following steps:

[0050] 0.001 mol Cu(CH3COO)2·H2O was dissolved in 5 mL of deionized water and stirred for 30 min until completely dissolved, yielding a Cu(CH3COO)2·H2O solution. After stirring, the stirring speed was maintained at 800 rpm, and 5 mL of 20% (w / w) H2O2 solution was slowly added dropwise to the Cu(CH3COO)2·H2O solution. A black precipitate rapidly formed in the solution, and the reaction was allowed to proceed at room temperature for 10 min. After the reaction was complete, the black precipitate was centrifuged at 6000 rpm, and the supernatant was discarded. The precipitate was washed three times with deionized water, with the final wash using anhydrous ethanol. After washing, the precipitate was freeze-dried under vacuum. The resulting powder was oxygen-vacancy CuO.

[0051] Example 5

[0052] The preparation method of oxygen-vacancy CuO according to this embodiment includes the following steps:

[0053] 0.002 mol Cu(CH3COO)2·H2O was dissolved in 5 mL of deionized water and stirred for 30 min until completely dissolved, yielding a Cu(CH3COO)2·H2O solution. After stirring, the stirring speed was maintained at 800 rpm, and 5 mL of 30% H2O2 solution was slowly added dropwise to the Cu(CH3COO)2·H2O solution. A black precipitate rapidly formed in the solution, and the reaction was allowed to proceed at room temperature for 5 min. After the reaction was complete, the black precipitate was centrifuged at 6000 rpm, and the supernatant was discarded. The precipitate was washed three times with deionized water, with the final wash using anhydrous ethanol. After washing, the precipitate was freeze-dried under vacuum. The resulting powder was oxygen-vacancy CuO.

[0054] Example 6

[0055] The preparation method of oxygen-vacancy CuO according to this embodiment includes the following steps:

[0056] 0.003 mol Cu(CH3COO)2·H2O was dissolved in 5 mL of deionized water and stirred for 30 min until completely dissolved, yielding a Cu(CH3COO)2·H2O solution. After stirring, the stirring speed was maintained at 800 rpm, and 5 mL of 15% H2O2 solution was slowly added dropwise to the Cu(CH3COO)2·H2O solution. A black precipitate rapidly formed in the solution, and the reaction was allowed to proceed at room temperature for 20 min. After the reaction was complete, the black precipitate was centrifuged at 6000 rpm, and the supernatant was discarded. The precipitate was washed three times with deionized water, with the final wash using anhydrous ethanol. After washing, the precipitate was freeze-dried under vacuum. The resulting powder was oxygen-vacancy CuO.

[0057] Example 7

[0058] The preparation method of oxygen-vacancy CuO according to this embodiment includes the following steps:

[0059] 0.001 mol Cu(CH3COO)2·H2O was dissolved in 5 mL of deionized water and stirred for 30 min until completely dissolved, yielding a Cu(CH3COO)2·H2O solution. After stirring, the stirring speed was maintained at 900 rpm, and 5 mL of 10% H2O2 solution was slowly added dropwise to the Cu(CH3COO)2·H2O solution. A black precipitate rapidly formed in the solution, and the reaction was allowed to proceed at room temperature for 10 min. After the reaction was complete, the black precipitate was centrifuged at 6000 rpm, and the supernatant was discarded. The precipitate was washed three times with deionized water, with the final wash using anhydrous ethanol. After washing, the precipitate was freeze-dried under vacuum. The resulting powder was oxygen-vacancy CuO.

[0060] Example 8

[0061] The preparation method of oxygen-vacancy CuO according to this embodiment includes the following steps:

[0062] 0.002 mol Cu(CH3COO)2·H2O was dissolved in 5 mL of deionized water and stirred for 30 min until completely dissolved, yielding a Cu(CH3COO)2·H2O solution. After stirring, the stirring speed was maintained at 800 rpm, and 10 mL of 15% H2O2 solution was slowly added dropwise to the Cu(CH3COO)2·H2O solution. A black precipitate rapidly formed in the solution, and the reaction was allowed to proceed at room temperature for 10 min. After the reaction was complete, the black precipitate was centrifuged at 6000 rpm, and the supernatant was discarded. The precipitate was washed three times with deionized water, with the final wash using anhydrous ethanol. After washing, the precipitate was freeze-dried under vacuum. The resulting powder was oxygen-vacancy CuO.

[0063] Example 9

[0064] The preparation method of oxygen-vacancy CuO according to this embodiment includes the following steps:

[0065] 0.002 mol Cu(CH3COO)2·H2O was dissolved in 10 mL of deionized water and stirred for 30 min until completely dissolved, yielding a Cu(CH3COO)2·H2O solution. After stirring, the stirring speed was maintained at 1000 rpm, and 5 mL of 15% H2O2 solution was slowly added dropwise to the Cu(CH3COO)2·H2O solution. A black precipitate rapidly formed in the solution, and the reaction was allowed to proceed at room temperature for 20 min. After the reaction was complete, the black precipitate was centrifuged at 6000 rpm, and the supernatant was discarded. The precipitate was washed three times with deionized water, with the final wash using anhydrous ethanol. After washing, the precipitate was freeze-dried under vacuum. The resulting powder was oxygen-vacancy CuO.

[0066] Application examples

[0067] Using the oxygen-vacancy-containing CuO prepared in Example 1 and commercially available CuO (Shanghai Aladdin Biochemical Technology Co., Ltd.) as photocatalytic materials, the photocatalytic degradation of tetracycline was tested:

[0068] The photocatalytic performance of the CuO sample was evaluated using tetracycline (30 mg / L) as the target pollutant. The reaction system consisted of 0.02 g of photocatalyst and 100 mL of tetracycline solution, with the temperature maintained at 0 °C using circulating cooling water. Before the photodegradation experiment, an adsorption experiment was conducted for 40 min to allow the reaction system to reach adsorption equilibrium. During the illumination phase, a 300 W xenon lamp was used at a distance of 10 cm. Every 20 min, 4 mL of tetracycline solution was centrifuged, and the supernatant was subjected to UV-Vis analysis. The absorption peak at 357 nm was used as the characteristic peak to assess the degradation efficiency. The adsorption and removal efficiencies of the tetracycline solution were calculated using the C / C0 ratio, where C represents the absorbance during adsorption and degradation, and C0 represents the initial absorbance of the tetracycline solution.

[0069] Figure 8 Figure a compares the performance of CuO and commercially available CuO. Taking the photodegradation of tetracycline (30 mg / L) as an example, it can be observed that the adsorption efficiency of the prepared oxygen-vacancy CuO for tetracycline is 22.1%, which is higher than that of commercially available CuO (4.7%). After the photodegradation experiment, the removal efficiency of commercially available CuO for tetracycline solution is 14%, while the removal efficiency of oxygen-vacancy CuO for tetracycline solution is 59.3%, which is 4.2 times that of commercially available CuO. Therefore, it can be concluded that the adsorption performance and photodegradation performance of oxygen-vacancy CuO are both higher than those of commercially available nano-CuO.

[0070] In addition, the photodegradation cycle stability test is an important indicator for evaluating the performance of photocatalysts. The photodegradation cycle stability was tested using the oxygen-vacancy CuO prepared in Example 1, and the results are as follows: Figure 8 As shown in figure b, after five photodegradation experiments, the removal efficiency of tetracycline decreased from 59.3% to 55%. The slight decrease in efficiency is due to the loss of a small amount of photocatalyst during collection after each photodegradation. (Material collection procedure: After each photodegradation experiment, the photocatalyst powder was collected, washed several times with deionized water and anhydrous ethanol, and then dried in a vacuum drying oven. The dried photocatalyst was then used to repeat the above photodegradation experiments.)

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing an oxygen-vacancy-containing CuO, characterized by, The H2O2 solution is added to the Cu(CH3COO)2·H2O solution, and the reaction is carried out at room temperature; after the reaction is completed, the mixed solution after the reaction is centrifuged to obtain a black precipitate, which is washed with deionized water and ethanol, and then vacuum freeze-dried to obtain the oxygen vacancy-containing CuO; wherein the mass fraction of the H2O2 solution is 10%-30%; the concentration of the Cu(CH3COO)2·H2O solution is 0.2-0.6 mol / L; the volume ratio of the H2O2 solution to the Cu(CH3COO)2·H2O solution is 1:(0.5-2); the stirring rate of the reaction is 800-1000 rmb / min, and the reaction time is 5-30 min. 2.The oxygen vacancy-containing CuO prepared by the preparation method of claim 1. 3.The application of the oxygen vacancy-containing CuO of claim 2 in photocatalytic degradation of organic pollutants.

4. Use according to claim 3, characterized in that, The organic pollutants are tetracycline.

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