Preparation method and application of zinc oxide-coated copper plasma composite photocatalytic material for degrading phenol

Abstract

The invention discloses a preparation method and application of a zinc oxide copper-coated plasma composite photocatalytic material for degrading phenol, and relates to a preparation method and application of a photocatalytic material. The invention aims to solve the problem that ROS (reactive oxygen species) generated by a semiconductor in a photocatalytic system is single and deficient due to a competitive relationship between excitons and free charge carriers in an existing semiconductor catalyst. According to the preparation method, a direct band gap semiconductor ZnO with a good exciton dissociation effect is taken as a substrate, bulk phase oxygen vacancies and elemental copper with a plasmon resonance effect are introduced in situ, the balance between excitons and photon-generated carriers is quasi-regulated, and the generation of rich oxidation active species in a photocatalytic system is realized. The method comprises the following steps: 1, mixing materials; and 2, hydrothermal reaction. The application is as follows: the photocatalyst is used for photocatalytic degradation of phenol. The invention relates to preparation and application of a zinc oxide-coated copper plasma composite photocatalytic material for degrading phenol.

Description

Technical Field

[0001] The present invention relates to a preparation method and application of a photocatalytic material. Background Art

[0002] Phenol, as a common organic compound, is widely used in industries such as chemical engineering, pharmaceuticals, and dyes. Due to its high toxicity and poor degradability, it is often discharged into the water environment as a major pollutant in industrial wastewater, posing a huge potential threat to water quality, ecological safety, and human health. Based on this, it is very necessary to effectively treat phenol pollutants in the water environment to protect the environment and public health. Currently, common phenol-containing wastewater treatment processes are mainly divided into traditional treatment processes, such as biological methods, chemical methods, and adsorption methods, etc., and advanced oxidation processes such as electrochemical oxidation, sonochemical oxidation, and photocatalytic degradation. Among them, the photocatalytic technology can convert low-density solar energy into high-density chemical energy through a photocatalyst, thereby achieving the complete mineralization of pollutants, minimizing the consumption of chemical drugs and the generation of secondary pollution, and having obvious advantages in terms of environmental friendliness and ease of operation.

[0003] As a representative radical in the photocatalytic degradation system, the hydroxyl radical exhibits excellent oxidation ability due to its high redox potential. However, its short half-life, harsh pH conditions, and sensitivity to inorganic ions limit its application in the degradation of organic pollutants. Although the superoxide radical has a longer half-life, its relatively low reactivity and oxidation ability also hinder the development of superoxide anions in the water environment. In addition, singlet oxygen, as the only oxygen-containing non-radical, has always attracted the attention of researchers due to its high selectivity, strong anti-interference ability, and good pH tolerance. At the same time, precisely because of the strong selectivity of singlet oxygen, it has poor universality in the degradation process of organic pollutants, and the expansion of its application range is greatly restricted. Therefore, a single reactive oxygen species has great limitations in treating phenol-containing wastewater. Enriching the generation of ROS and its synergistic catalytic oxidation effect is a potential development trend for the removal of pollutants in complex water environments.

[0004] In recent years, the photocatalytic advanced oxidation process based on semiconductor catalysts has attracted much attention from researchers due to its high efficiency, environmental friendliness, and other characteristics. At the same time, due to the special band structure and light response characteristics of semiconductors, carriers (photo-generated electron-hole pairs) or excitons (bound states of photo-generated electron-hole pairs) will be generated inside them under photoexcitation conditions. Among them, the existence of charge carriers is beneficial to reducing oxygen or activating water molecules to generate superoxide anions and hydroxyl radicals respectively. In addition, excitons can also directly excite oxygen molecules through an energy transfer process to generate singlet oxygen. However, from the perspective of the separation of electrons and holes, the existence of excitons and carriers in a single semiconductor is a complementary regular relationship (excitons dissociate into free charge carriers, and the bound state of photo-generated carriers is excitons), resulting in the ROS generated by semiconductors in the photocatalytic system being often single and scarce. Therefore, precisely regulating semiconductor photocatalysts with both exciton and carrier effects to achieve a reasonable balance between the generation of excitons and carriers, so as to promote the generation of multiple types of reactive oxygen species, has important practical significance for solving environmental problems. Summary of the Invention

[0005] The present invention aims to solve the problem that there is a competitive relationship between excitons and free charge carriers in existing semiconductor catalysts, resulting in single and scarce ROS generated by semiconductors in the photocatalytic system. Furthermore, a preparation method and application of a zinc oxide-coated copper plasmonic composite photocatalytic material for degrading phenol are provided. The present invention uses the direct bandgap semiconductor ZnO with good exciton dissociation effect as the substrate, and effectively balances the generation competition relationship between excitons and free charge carriers by in-situ introducing bulk oxygen vacancies and elemental copper with surface plasmon resonance effect, precisely regulates the balance between excitons and photo-generated carriers, greatly improves the generation path of reactive oxygen species, thereby realizing the enrichment of the generation of oxidative active species in the photocatalytic system. The prepared catalyst has excellent LSPR effect and abundant bulk oxygen defects, and exhibits excellent photocatalytic degradation activity in the treatment of phenol-containing wastewater.

[0006] A preparation method of a zinc oxide-coated copper plasmonic composite photocatalytic material for degrading phenol is carried out according to the following steps:

[0007] I. Material mixing:

[0008] At room temperature, copper nitrate trihydrate, glucose, and nano-zinc oxide are added to an organic solvent, stirred, and then ultrasonicated to obtain a mixed solution;

[0009] II. Hydrothermal reaction:

[0010] Under the condition that the temperature is 160 °C to 180 °C, the mixed solution is hydrothermally reacted for 6 h to 12 h, then naturally cooled to room temperature, and finally filtered, washed and dried to obtain Cu@ZnO-C, that is, the preparation method of the copper oxide-coated zinc oxide plasma composite photocatalytic material for degrading phenol is completed.

[0011] An application of a copper oxide-coated zinc oxide plasma composite photocatalytic material for degrading phenol, which is used as a photocatalyst for photocatalytic degradation of phenol.

[0012] The beneficial effects of the present invention are as follows:

[0013] The present invention provides a photocatalytic material for degrading phenol. Through a simple one-pot hydrothermal synthesis process, a heterojunction material rich in bulk oxygen vacancies is in-situ constructed. By introducing plasma metal Cu and bulk oxygen vacancies, a catalyst with local surface plasmon resonance (LSPR) effect and efficient intersystem crossing (ISC) process is synthesized. This unique design enables the catalyst to effectively balance the generation competition between excitons and carriers, thereby promoting the generation of multiple types of reactive oxygen species. Among them, bulk oxygen vacancies serve as the recombination center of excitons and carriers, contributing to the generation of singlet excitons in the photocatalytic system. Through the efficient ISC process, singlet excitons are further converted into triplet excitons, which helps to directly activate molecular oxygen during the energy transfer process, accelerate the energy transfer, and generate non-radical singlet oxygen. In addition, the LSPR effect injects a large number of high-energy carriers into the photocatalytic system. These carriers are rapidly transferred by hot electrons driven by the built-in electric field, significantly improving the generation efficiency of free charge carriers, contributing to more electrons and holes participating in the generation process of ROS, and further stimulating the generation of more highly active free radicals. Therefore, the optimized Cu@ZnO-C heterojunction exhibits excellent photocatalytic activity and can achieve 100% degradation of phenol within 30 min. At the same time, Cu@ZnO-C also exhibits excellent photocatalytic degradation effects on other pollutants, demonstrating the good universality of the catalyst. Therefore, the present invention provides a new strategy for exploring photocatalysts for the generation of multi-path reactive oxygen species. Description of the Drawings

[0014] Figure 1 X-ray diffraction patterns of the photocatalytic materials prepared in Example 1 and Comparative Examples 1 to 3;

[0015] Figure 2 Scanning electron microscope image of the photocatalytic material prepared in Example 1;

[0016] Figure 3 Transmission electron microscope image of the photocatalytic material prepared in Example 1;

[0017] Figure 4UV-Vis diffuse reflectance spectra of the photocatalytic materials prepared in Example 1 and Comparative Examples 1 to 3;

[0018] Figure 5 Surface potential diagrams and corresponding surface photovoltage diagrams of the photocatalytic materials prepared in Example 1 and Comparative Example 1. a1 is the surface potential diagram and corresponding surface photovoltage diagram of ZnO under dark conditions, a2 is the surface potential diagram and corresponding surface photovoltage diagram of ZnO under illumination conditions, b1 is the surface potential diagram and corresponding surface photovoltage diagram of Cu@ZnO-C under dark conditions, and b2 is the surface potential diagram and corresponding surface photovoltage diagram of Cu@ZnO-C under illumination conditions;

[0019] Figure 6 Infrared thermal imaging diagrams of the photocatalytic materials prepared in Example 1 and Comparative Example 1. a is ZnO and b is Cu@ZnO-C;

[0020] Figure 7 Fluorescence and phosphorescence spectra of the photocatalyst materials prepared in Example 1 and Comparative Example 1. a is the steady-state transient fluorescence spectrum, b is the transient fluorescence spectrum, c is the steady-state phosphorescence spectrum diagram, and d is the transient phosphorescence spectrum diagram;

[0021] Figure 8 Electron spin resonance spectra of the photocatalytic materials prepared in Example 1 and Comparative Examples 1 to 3. a is the quenching experiment diagram of the photocatalytic material prepared in Example 1, b is the change in singlet oxygen intensity of the photocatalytic material prepared in Example 1 before and after adding p-benzoquinone, c is the change in hole signal of the photocatalytic material prepared in Example 1 under light and dark conditions, and d, e, and f are the electron paramagnetic spin resonance spectra of hydroxyl radicals, singlet oxygen radicals, and superoxide radicals of the photocatalytic materials prepared in Example 1 and Comparative Examples 1 to 3, respectively;

[0022] Figure 9 Electron spin resonance spectra of the photocatalytic materials prepared in Example 1 and Comparative Examples 1 to 3;

[0023] Figure 10 Photocatalytic degradation performance diagrams of the photocatalytic materials prepared in Example 1 and Comparative Examples 1 to 3;

[0024] Figure 11 Cyclic stability test diagram of the photocatalytic material prepared in Example 1. Detailed implementation manners

[0025] Detailed implementation manner 1: This implementation manner is a preparation method of a copper-coated zinc oxide plasma composite photocatalytic material for degrading phenol, and it is carried out according to the following steps:

[0026] I. Material mixing:

[0027] At room temperature, copper nitrate trihydrate, glucose, and nano-zinc oxide are added to an organic solvent, stirred, and then sonicated to obtain a mixed solution;

[0028] II. Hydrothermal reaction:

[0029] Under the condition that the temperature is 160 °C to 180 °C, the mixed solution is subjected to hydrothermal reaction for 6 h to 12 h, then naturally cooled to room temperature, and finally filtered, washed, and dried to obtain Cu@ZnO-C, that is, the preparation method of the zinc oxide-coated copper plasma composite photocatalytic material for degrading phenol is completed.

[0030] The beneficial effects of this embodiment are:

[0031] This embodiment provides a photocatalytic material for degrading phenol. Through a simple one-pot hydrothermal synthesis process, a heterojunction material rich in bulk oxygen vacancies is in-situ constructed. By introducing the plasma metal Cu and bulk oxygen vacancies, a catalyst with local surface plasmon resonance (LSPR) effect and efficient intersystem crossing (ISC) process is synthesized. This unique design enables the catalyst to effectively balance the generation competition between excitons and carriers, thereby promoting the generation of multiple types of reactive oxygen species. Among them, bulk oxygen vacancies, as the recombination centers of excitons and carriers, contribute to the generation of singlet excitons in the photocatalytic system. Through the efficient ISC process, singlet excitons are further converted into triplet excitons, which helps to directly activate molecular oxygen during the energy transfer process, accelerates the energy transfer, and generates non-radical singlet oxygen. In addition, the LSPR effect injects a large number of high-energy carriers into the photocatalytic system. These carriers are rapidly transferred by hot electrons driven by the built-in electric field, significantly improving the generation efficiency of free charge carriers, helping more electrons and holes to participate in the ROS generation process, and thus stimulating the generation of more highly active free radicals. Therefore, the optimized Cu@ZnO-C heterojunction exhibits excellent photocatalytic activity. Within 30 min, 100% degradation of phenol can be achieved. At the same time, Cu@ZnO-C also exhibits excellent photocatalytic degradation effects on other pollutants, proving that the catalyst has good universality. Therefore, this embodiment provides a new strategy for exploring photocatalysts for multi-path reactive oxygen species generation.

[0032] Specific embodiment two: The difference between this embodiment and specific embodiment one is that the organic solvent described in step one is an N,N-dimethylformamide solution. Others are the same as specific embodiment one.

[0033] Specific embodiment three: The difference between this embodiment and one of specific embodiments one or two is that the mass ratio of glucose to copper nitrate trihydrate in step one is 1:(2 - 5). Others are the same as specific embodiments one or two.

[0034] Embodiment 4: The difference between this embodiment and any one of Embodiments 1 to 3 is that: the mass ratio of glucose to nano-zinc oxide in Step 1 is 1:(60 - 70). Others are the same as those in Embodiments 1 to 3.

[0035] Embodiment 5: The difference between this embodiment and any one of Embodiments 1 to 4 is that: the mass ratio of glucose to the volume of the organic solvent in Step 1 is 1g:(1100 - 1200)mL. Others are the same as those in Embodiments 1 to 4.

[0036] Embodiment 6: The difference between this embodiment and any one of Embodiments 1 to 5 is that: in Step 1, at room temperature, cupric nitrate trihydrate, glucose and nano-zinc oxide are added to the organic solvent, and then under the condition that the stirring speed is 200 rpm - 500 rpm, stir for 5 min - 10 min, and then under the condition that the power is 100 kW - 400 kW, ultrasonicate for 15 min - 45 min to obtain a mixed solution. Others are the same as those in Embodiments 1 to 5.

[0037] Embodiment 7: The difference between this embodiment and any one of Embodiments 1 to 6 is that: the washing and drying in Step 2 are specifically carried out by washing with deionized water and absolute ethanol, and then under the condition that the temperature is 40°C - 60°C, vacuum dry for 8 h - 12 h. Others are the same as those in Embodiments 1 to 6.

[0038] Embodiment 8: The application of a copper-coated zinc oxide plasma composite photocatalytic material for degrading phenol in this embodiment, which is used as a photocatalyst for photocatalytic degradation of phenol.

[0039] Embodiment 9: The difference between this embodiment and Embodiment 8 is that: it is used as a photocatalyst for photocatalytic degradation of phenol, and specifically is carried out according to the following steps:

[0040] Mix Cu@ZnO-C with the solution to be treated, and then under the conditions of a wavelength of 320 nm - 780 nm and a power density of 1.767 W / cm 2 - 7.07 W / cm 2 irradiate for 30 min - 90 min. Others are the same as those in Embodiment 8.

[0041] Embodiment 10: The difference between this embodiment and any one of Embodiments 8 or 9 is that: the mass ratio of Cu@ZnO-C to the volume of the solution to be treated is 10 mg:(50 - 100)mL; the concentration of phenol in the solution to be treated is 10 mg / L - 1000 mg / L. Others are the same as those in Embodiments 8 or 9.

[0042] The following examples are used to verify the beneficial effects of the present invention:

[0043] Example 1:

[0044] A preparation method of a copper - coated zinc oxide plasma composite photocatalytic material for degrading phenol, which is carried out according to the following steps:

[0045] I. Material mixing:

[0046] At room temperature, 0.0968 g of copper nitrate trihydrate, 0.036 g of glucose and 2.33 g of nano - zinc oxide are added to 40 mL of an organic solvent, and then under the condition of a stirring speed of 400 rpm, stirred for 5 min, and then under the condition of a power of 300 kW, ultrasonicated for 30 min to obtain a mixed solution;

[0047] The particle size of the nano - zinc oxide is 80 nm to 100 nm; the organic solvent is an N,N - dimethylformamide solution;

[0048] II. Hydrothermal reaction:

[0049] The mixed solution is placed in a sealed stainless - steel high - pressure reaction kettle with a polytetrafluoroethylene inner liner, and under the condition of a temperature of 180 °C, the mixed solution is subjected to hydrothermal reaction for 6 h, then naturally cooled to room temperature, and finally filtered, washed and dried to obtain a photocatalytic material, namely Cu@ZnO - C;

[0050] The washing and drying in step II are specifically carried out by washing 3 times with deionized water and absolute ethanol, and then under the condition of a temperature of 60 °C, vacuum - dried for 12 h.

[0051] Comparative Example 1: The difference between this comparative example and Example 1 is that: in step I, copper nitrate trihydrate and glucose are omitted, and 2.33 g of nano - zinc oxide is added to 40 mL of water; ZnO is obtained in step II. Others are the same as in Example 1.

[0052] Comparative Example 2: The difference between this comparative example and Example 1 is that: in step I, glucose is omitted, and 0.0968 g of copper nitrate trihydrate and 2.33 g of nano - zinc oxide are added to 40 mL of an organic solvent; Cu@ZnO is obtained in step II. Others are the same as in Example 1.

[0053] Comparative Example 3:

[0054] I. Material mixing:

[0055] At room temperature, 2.33 g of nano - zinc oxide is added to 40 mL of a glucose aqueous solution with a concentration of 0.005 M, and then under the condition of a stirring speed of 400 rpm, stirred for 5 min, and then under the condition of a power of 300 kW, ultrasonicated for 30 min to obtain a mixed solution;

[0056] The particle size of the nano zinc oxide described is 80 nm to 100 nm;

[0057] II. Hydrothermal reaction:

[0058] The mixed solution is placed in a sealed stainless steel high-pressure reaction kettle with a polytetrafluoroethylene inner liner. Under the condition of a temperature of 180 °C, the mixed solution is subjected to hydrothermal reaction for 6 h, and then naturally cooled to room temperature. Under the condition of a rotation speed of 10,500 revolutions per minute, centrifugation is carried out for 10 min to separate the supernatant and the precipitate. Finally, the precipitate is washed and dried to obtain the photocatalytic material, namely ZnO@C;

[0059] The washing and drying described in step II specifically mean washing 3 times with deionized water and absolute ethanol, and then drying in vacuum for 12 h under the condition of a temperature of 60 °C.

[0060] Figure 1 It is the X-ray diffraction pattern of the photocatalytic materials prepared in Example 1 and Comparative Examples 1 to 3. As can be seen from the figure, the Cu@ZnO-C photocatalyst shows eleven characteristic diffraction peaks at 31.76°, 34.42°, 36.25°, 47.53°, 56.60°, 62.86°, 66.37°, 67.96°, 69.09°, 72.56° and 76.95°, which respectively correspond to the (100), (002), (101), (102), (110), (103), (200), (112), (201), (004) and (202) crystal planes of ZnO. In addition, three obvious diffraction peaks at 43.29°, 50.43°, and 74.13° respectively belong to the (111), (200) and (220) crystal planes of Cu.

[0061] Figure 2 It is the scanning electron microscope image of the photocatalytic material prepared in Example 1. As can be seen from the figure, irregular spherical ZnO particles are dispersed around metallic Cu.

[0062] Figure 3 It is the transmission electron microscope image of the photocatalytic material prepared in Example 1. As can be seen from the figure, clear lattice fringes of Cu@ZnO-C are measured, and the spacings are 0.22 nm and 0.273 nm, which respectively correspond to the (111) crystal plane of Cu and the (002) characteristic plane of zinc oxide.

[0063] Figure 4UV-Vis diffuse reflectance spectra of the photocatalytic materials prepared in Example 1 and Comparative Examples 1 to 3. As can be seen from the figure, compared with pure ZnO, the Cu@ZnO-C composite catalyst shows significantly enhanced light absorption in the near-infrared region. This enhancement is attributed to the near-field coupling and far-field scattering effects caused by the local surface plasmon resonance effect. Calculated by the Tauc formula, the band gap width (Eg) of ZnO is 3.242 eV, while that of the Cu@ZnO-C composite catalyst is reduced to 3.228 eV. This result indicates that the LSPR effect introduced by metallic Cu not only effectively reduces the band gap width of the photocatalyst but also significantly expands its light response range.

[0064] Figure 5 Surface potential maps and corresponding surface photovoltage maps of the photocatalytic materials prepared in Example 1 and Comparative Example 1. a1 is the surface potential map and corresponding surface photovoltage map of ZnO under dark conditions, a2 is the surface potential map and corresponding surface photovoltage map of ZnO under illumination conditions, b1 is the surface potential map and corresponding surface photovoltage map of Cu@ZnO-C under dark conditions, and b2 is the surface potential map and corresponding surface photovoltage map of Cu@ZnO-C under illumination conditions; as can be seen from the figure, for the Cu@ZnO-C heterojunction, under illumination conditions, the potential at site C rises from 1062 mV to 1082 mV (denoted as C2), while the potential at site D drops from 1017.49 mV to 1017.31 mV (denoted as D2). This change indicates that the transfer process of electrons from site C to site D is closely related to the introduction of light. In contrast, the potential change of ZnO before and after illumination is not obvious. In addition, the surface potential displacement difference (ΔSP) of Cu@ZnO-C is larger, further indicating that its electron transfer process is more intense. These results show that in the composite photocatalyst Cu@ZnO-C, the hot carriers on Cu can effectively transfer to ZnO under illumination conditions.

[0065] Irradiate the photocatalytic materials prepared in Example 1 and Comparative Example 1 with a xenon lamp with a power of 300 W and a current of 15 A; Figure 6 Infrared thermal imaging maps of the photocatalytic materials prepared in Example 1 and Comparative Example 1. a is ZnO, and b is Cu@ZnO-C. As can be seen from the figure, after 60 seconds of xenon lamp irradiation, the central temperatures of ZnO and Cu@ZnO-C rise to 91.9 °C and 123.9 °C, respectively. This result indicates that the heating rate of the Cu@ZnO-C composite photocatalyst is significantly higher than that of pure ZnO. This significant temperature difference indicates that the presence of Cu enables energy to be efficiently transferred from Cu to ZnO under illumination conditions. In addition, the Cu@ZnO-C composite photocatalyst exhibits better photothermal conversion ability, which further proves the existence of the local surface plasmon resonance (LSPR) effect and its significant enhancement of the photothermal performance.

[0066] Figure 7 Fluorescence and phosphorescence spectra of the photocatalyst materials prepared in Example 1 and Comparative Example 1. a is the steady-state transient fluorescence spectrum, b is the transient fluorescence spectrum, c is the steady-state phosphorescence spectrum, and d is the transient phosphorescence spectrum; in Figure 7 a, the peak value of the fluorescence spectrum of the Cu@ZnO-C sample is lower than that of the ZnO sample, indicating that the concentration of singlet excitons in the Cu@ZnO-C photocatalytic system is relatively low, which may be due to the rapid conversion of singlet excitons ( Figure 7 a). In Figure 7 b, the fluorescence lifetimes of Cu@ZnO-C and ZnO are 13.38 μs and 21.84 μs, respectively, indicating that the conversion rate of singlet excitons to triplet excitons in Cu@ZnO-C is faster, resulting in a significant shortening of the fluorescence lifetime. In Figure 7 c, the phosphorescence intensity of Cu@ZnO-C is higher than that of ZnO, indicating that the yield of triplet excitons in the Cu@ZnO-C system is higher, which is beneficial to the generation of singlet oxygen through the energy transfer process. In Figure 7 d, the phosphorescence lifetimes of Cu@ZnO-C and ZnO are 11.06 ms and 7.15 ms, respectively. Overall, the fluorescence intensity of the Cu@ZnO-C sample decreases, the fluorescence lifetime shortens, while the phosphorescence intensity increases and the phosphorescence lifetime prolongs. These results indicate that the conversion efficiency of singlet excitons to triplet excitons in Cu@ZnO-C is significantly improved.

[0067] Figure 8 Electron spin resonance spectra of the photocatalytic materials prepared in Example 1, Comparative Examples 1 to 3. a is the quenching experiment diagram of the photocatalytic material prepared in Example 1, b is the change in singlet oxygen intensity before and after adding p-benzoquinone to the photocatalytic material prepared in Example 1, c is the change in hole signal of the photocatalytic material prepared in Example 1 under light and dark conditions, and d, e, and f are the electron paramagnetic spin resonance spectra of hydroxyl radicals, singlet oxygen radicals, and superoxide radicals of the photocatalytic materials prepared in Example 1, Comparative Examples 1 to 3, respectively; it can be seen from Figure a that singlet oxygen, holes, and hydroxyl radicals play important roles in the photocatalytic degradation of phenol. Figure b shows that the intensity of singlet oxygen decreases significantly after adding p-benzoquinone (p-BQ), which proves that singlet oxygen is generated through an energy transfer mechanism, and at the same time Figure 6 and 7 a can prove that the generation process is closely related to the mediation of excitons. Figure c shows the existence of holes in the catalyst. Figures d, e, and f prove the diversity of reactive oxygen species in the photocatalytic system, indicating that the catalyst can effectively generate a variety of reactive oxygen species, thus promoting the photocatalytic degradation process.

[0068] Figure 9EPR spectra of the photocatalytic materials prepared in Example 1 and Comparative Examples 1 to 3; as can be seen from the figure, the composite photocatalytic material has a higher concentration of bulk oxygen vacancies as shown by the EPR signal intensity.

[0069] Mix 10 mg of the photocatalytic material with 100 mL of the solution to be treated, first perform a dark reaction for 30 min to avoid the influence of adsorption on the test results, and then irradiate for 90 min under the conditions of a wavelength of 320 nm to 780 nm and a power density of 2.55 W / cm 2 . The concentration of phenol in the solution to be treated is 10 mg / L; during the cyclic test, after the reaction, the catalyst is recovered by suction filtration, and then the recovered catalyst is added to a new batch of the solution to be treated and treated again under the above conditions, and this cycle is repeated 5 times. The test results are as Figures 10 to 11 .

[0070] Figure 10 Photocatalytic degradation performance diagrams of the photocatalytic materials prepared in Example 1 and Comparative Examples 1 to 3. Under light irradiation conditions, the composite material Cu@ZnO-C can achieve a 100% degradation effect after 30 min.

[0071] Figure 11 Cyclic stability test diagram of the photocatalytic material prepared in Example 1. The results show that the sample performs excellently during the degradation of phenol, and the degradation efficiency is always stable above 95%, showing extremely excellent performance stability.

[0072] In summary, the Cu@ZnO-C heterojunction with rich bulk oxygen defects and excellent LSPR effect successfully realizes the dynamic balance of excitons and free charge carriers, and establishes a platform for the multi-path efficient generation of reactive oxygen species in the photocatalytic degradation system. Photoluminescence analysis shows that bulk oxygen vacancies, as electron-hole recombination centers, effectively promote the formation of singlet excitons, which helps the energy transfer pathway to drive the in-situ activation of molecular oxygen to generate long-lived non-radical singlet oxygen. At the same time, the high-energy hot electrons induced by the LSPR effect migrate directionally under the action of the built-in electric field, significantly improving the separation efficiency of electron-hole pairs and enhancing the concentration of hydroxyl and superoxide radicals in the photocatalytic degradation system. Through the synergistic effect of free radicals and non-free radicals, the Cu@ZnO-C heterojunction exhibits excellent photocatalytic degradation performance and can completely degrade phenol within 30 min. At the same time, the heterojunction also shows high degradation ability for various organic pollutants, proving that the catalyst has good universality. This preparation scheme provides a new idea for the development of photocatalysts for multi-path reactive species generation.

Claims

1. A method for preparing a zinc oxide-coated copper plasma composite photocatalytic material for degrading phenol, characterized in that It is carried out in the following steps:

1. Material mixing: At room temperature, copper nitrate trihydrate, glucose and nano zinc oxide are added into an organic solvent, stirred and then ultrasonicated to obtain a mixed solution; 2. Hydrothermal reaction: At a temperature of 160°C to 180°C, the mixed solution is hydrothermally reacted for 6h to 12h, then naturally cooled to room temperature, and finally filtered, washed and dried to obtain Cu@ZnO-C, thereby completing the preparation method of zinc oxide-coated copper plasma composite photocatalytic material for degrading phenol.

2. The method for preparing a zinc oxide copper-coated plasma composite photocatalytic material for degrading phenol according to claim 1, characterized in that The organic solvent described in step 1 is N,N-dimethylformamide solution.

3. The method for preparing a zinc oxide-coated copper plasma composite photocatalytic material for degrading phenol according to claim 1, characterized in that The mass ratio of glucose to copper nitrate trihydrate described in step 1 is 1:(2-5).

4. The method for preparing a zinc oxide-coated copper plasma composite photocatalytic material for degrading phenol according to claim 1, characterized in that The mass ratio of glucose to nano zinc oxide described in step 1 is 1:(60-70).

5. The method for preparing a zinc oxide-coated copper plasma composite photocatalytic material for degrading phenol according to claim 1, characterized in that The mass ratio of glucose to the volume of the organic solvent described in step 1 is 1 g: (1100-1200) mL.

6. The method for preparing a zinc oxide-coated copper plasma composite photocatalytic material for degrading phenol according to claim 1, characterized in that In step 1, copper nitrate trihydrate, glucose and nano zinc oxide are added to an organic solvent at room temperature, and then stirred for 5 to 10 minutes at a stirring speed of 200 to 500 rpm, and then ultrasonicated for 15 to 45 minutes at a power of 100 to 400 kW to obtain a mixed solution.

7. The method for preparing a zinc oxide-coated copper plasma composite photocatalytic material for degrading phenol according to claim 1, characterized in that The washing and drying in step 2 specifically involves washing with deionized water and anhydrous ethanol, and then vacuum drying at a temperature of 40° C. to 60° C. for 8 h to 12 h.

8. Use of a zinc oxide-coated copper plasma composite photocatalytic material for degrading phenol prepared as claimed in claim 1, characterized in that It was used as a photocatalyst for the photocatalytic degradation of phenol.

9. The use of a zinc oxide-coated copper plasma composite photocatalytic material for degrading phenol according to claim 8, characterized in that It is used as a photocatalyst for the photocatalytic degradation of phenol, specifically in the following steps: The Cu@ZnO-C was mixed with the solution to be treated, and then heated at a wavelength of 320 nm to 780 nm and a power density of 1.767 W / cm 2 ~7.07W / cm 2 Under the conditions of light treatment, 30min to 90min.

10. The use of a zinc oxide-coated copper plasma composite photocatalytic material for degrading phenol according to claim 8, characterized in that The mass ratio of the Cu@ZnO-C to the volume of the solution to be treated is 10 mg: (50-100) mL; the concentration of phenol in the solution to be treated is 10 mg / L-1000 mg / L.

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