阅读说明：本技术 一种铜基异质结催化剂及其制备方法、应用 (Copper-based heterojunction catalyst and preparation method and application thereof ) 是由 王琼 陈春梅 常春 于 2021-07-20 设计创作，主要内容包括：本发明公开了一种铜基异质结催化剂的制备方法及应用。本发明利用溶剂热法制备了具有丰富孔隙的空心球形CuCo-(2)O-(4),然后以硫化钠为硫源,在水热环境中将部分CuCo-(2)O-(4)中的晶格氧取代,原位转化为CuCo-(2)S-(4),形成界面连接紧密的CuCo-(2)S-(4)@CuCo-(2)O-(4)异质结,将其作为双功能催化剂用于光催化氧化降解DCF和还原Cr(Ⅲ),解决了现有技术中的催化剂普遍存在的光生载流子分离效率差、光谱吸收范围窄的问题。(The invention discloses a preparation method and application of a copper-based heterojunction catalyst. The invention prepares hollow spherical CuCo with rich pores by using a solvothermal method 2 O 4 Then taking sodium sulfide as a sulfur source, and removing sodium sulfide in a hydrothermal environmentSeparating CuCo 2 O 4 In-situ conversion to CuCo 2 S 4 Form CuCo with tight interface connection 2 S 4 @CuCo 2 O 4 The heterojunction is used as a bifunctional catalyst for photocatalytic oxidative degradation of DCF and reduction of Cr (III), and solves the problems of poor separation efficiency and narrow spectral absorption range of a photo-generated carrier commonly existing in the catalyst in the prior art.)

1. The copper-based heterojunction catalyst is characterized in that the catalyst is CuCo₂S₄@CuCo₂O₄A composite material.

2. The copper-based heterojunction catalyst according to claim 1, wherein the CuCo is₂S₄@CuCo₂O₄In the composite material, CuCo₂S₄With CuCo₂O₄In a molar ratio of 1:1, 1:2, 2:1 or 3: 1.

3. The preparation method of the copper-based heterojunction catalyst is characterized by comprising the following steps of:

1) preparation of hollow bodies by solvothermal methodSpherical CuCo₂O₄；

2) Sodium sulfide is used as a sulfur source, and part of CuCo is removed in a hydrothermal environment₂O₄In-situ conversion to CuCo₂S₄Form CuCo with tight interface connection₂S₄@CuCo₂O₄A heterojunction catalyst;

wherein the addition of the sulfur source can control CuCo in the semiconductor heterojunction₂O₄And CuCo₂S₄The catalytic performance of the catalyst is further regulated and controlled.

4. The method for preparing a copper-based heterojunction catalyst according to claim 3,

the step 1) of preparing hollow spherical CuCo₂O₄The specific method comprises the following steps: mixing glycerol and isopropanol to obtain a transparent solution; weighing cobalt nitrate hexahydrate and copper nitrate trihydrate, pouring the cobalt nitrate hexahydrate and the copper nitrate trihydrate into the transparent solution, and dissolving to obtain a pink solution; pouring the pink solution into a high-pressure reaction kettle to react for 8-10h at the temperature of 180-; and (4) cooling to room temperature, pouring out the supernatant, putting the obtained precipitate into a centrifuge tube, washing and drying.

5. The method for preparing the copper-based heterojunction catalyst according to claim 3, wherein the step 2) is specifically: preparation of Na₂S solution and CuCo₂O₄Mixing, stirring, transferring into a reaction kettle, reacting at the temperature of 120-; then calcining the dried sample in a muffle furnace for 2-3h at the heating rate of 3-5 ℃/min to obtain CuCo₂S₄@CuCo₂O₄A composite material.

6. The copper-based heterojunction catalyst according to claim 1 or 2, applied to photocatalytic degradation of DCF and reduction of Cr (III).

Technical Field

The invention relates to the technical field of semiconductor materials, in particular to a copper-based heterojunction catalyst and a preparation method and application thereof.

Background

Because dyes, additives, pesticides and medicines are widely used in the fields of industrial production, food processing, planting, livestock raising, aquaculture and the like, and the phenomena of messy use and abuse exist in the using process, the content of organic pollutants in the environmental water body is seriously exceeded, and the pollutants with higher teratogenicity and carcinogenicity enter human bodies through direct contact or food chain enrichment, so that the human health is threatened all the time. Most organic pollutants are extremely strong in chemical stability and difficult to self-degrade under natural conditions, and biological treatment and common physical treatment are adopted, so that not only are the operation steps complicated, but also the organic pollutants are difficult to completely decompose. Therefore, there is an urgent need to develop an inexpensive, efficient, green, and environmentally friendly treatment technology to convert highly toxic, persistent organic pollutants into non-toxic or low-toxic substances.

Solar energy is used as a clean and renewable natural resource, and the optimal strategy for solving the problems of energy crisis and environmental pollution is to capture and convert the solar energy. The semiconductor photocatalysis technology can realize the high-efficiency utilization of solar energy, and has the advantages of no secondary pollution to the environment, thorough degradation and reaction at normal temperature and normal pressure. For example, industrial wastewater often contains a large amount of heavy metal ions, and expensive heavy metal ions such as Hg, Pt, Pb, Ag and the like can be reduced and deposited on the surface of a catalyst by virtue of a photocatalytic reaction, so that the pollution of heavy metals is reduced, and the heavy metals can be further recycled. Various organic pollutants (herbicides, insecticides, dyes, antibiotics, phenols and the like) in the environmental wastewater can be directly oxidized and decomposed into non-toxic and harmless organic micromolecules, carbon dioxide and water by utilizing the photocatalysis technology. The organic pesticide containing phosphorus and sulfur can be completely inorganic to generate corresponding PO₄ ^3-And SO₄ ^2-. Structurally stable antibiotics (tetracyclines, sulfonamides, quinolones, macrolides and chloramphenics) can be directly mineralized. The treatment of dye waste water by using the photocatalysis technology can greatly reduce the chroma of the dye,the light transmittance of the water body is increased, and carcinogens such as benzene rings, amino groups, azo groups and the like in dye molecules are thoroughly degraded. However, as the organic pollutant components tend to be complicated and the number and the types thereof sharply increase, the degradation difficulty is remarkably increased, and the requirements on the performance of the photocatalyst are higher and higher.

In conclusion, the semiconductor photocatalysis technology has the advantages of capability of directly utilizing solar energy, thorough degradation, no secondary pollution and reaction at normal temperature and normal pressure, and shows great potential in the field of environmental purification. However, the photocatalyst serving as the core of the technology still faces the problems of narrow spectral response range and low separation efficiency of photon-generated carriers, so that the actual catalytic capacity of the catalyst is far lower than the theoretical value of the catalyst, and the large-scale application of the photocatalytic technology is severely restricted.

Disclosure of Invention

In view of this, the invention discloses and provides a copper-based heterojunction catalyst, and a preparation method and application thereof, so as to solve the problems of poor separation efficiency and narrow spectral absorption range of a photo-generated carrier commonly existing in the existing catalyst.

In a first aspect, the invention provides a copper-based heterojunction catalyst, wherein the catalyst is CuCo₂S₄@CuCo₂O₄A composite material.

Preferably, the CuCo₂S₄@CuCo₂O₄In the composite material, CuCo₂S₄With CuCo₂O₄In a molar ratio of 1:1, 1:2, 2:1 or 3: 1.

In a second aspect, the present invention provides a method for preparing a copper-based heterojunction catalyst, comprising the following steps:

1) method for preparing hollow spherical CuCo by solvothermal method₂O₄；

2) Sodium sulfide is used as a sulfur source, and part of CuCo is removed in a hydrothermal environment₂O₄In-situ conversion to CuCo₂S₄Form CuCo with tight interface connection₂S₄@CuCo₂O₄A heterojunction interface catalyst;

wherein the addition amount of sulfur source can be controlled in the semiconductor heterojunctionCuCo₂O₄And CuCo₂S₄The ratio of (a) to (b).

Preferably, the step 1) of preparing the hollow spherical CuCo₂O₄The specific method comprises the following steps: mixing glycerol and isopropanol to obtain a transparent solution; weighing cobalt nitrate hexahydrate and copper nitrate trihydrate, pouring the cobalt nitrate hexahydrate and the copper nitrate trihydrate into the transparent solution, and dissolving to obtain a pink solution; pouring the pink solution into a high-pressure reaction kettle to react for 8-10h at the temperature of 180-; and (4) cooling to room temperature, pouring out the supernatant, putting the obtained precipitate into a centrifuge tube, washing and drying.

Preferably, the step 2) is specifically: preparation of Na₂S solution and CuCo₂O₄Mixing, stirring, transferring into a reaction kettle, reacting at the temperature of 120-; then calcining the dried sample in a muffle furnace for 2-3h at the heating rate of 3-5 ℃/min to obtain CuCo₂S₄@CuCo₂O₄A composite material.

In a third aspect, the invention provides the use of a copper-based heterojunction catalyst, which can be used in the photocatalytic degradation of DCF and the reduction of Cr (iii).

The invention has the beneficial effects that:

the invention provides a copper-based heterojunction catalyst and a preparation method and application thereof₂O₄Inducing CuCo₂S₄The heterojunction semiconductor with low energy barrier interface is formed by in-situ growth, and the introduction of inorganic element S can reduce CuCo₂O₄The forbidden band width of the light-absorbing material widens the light absorption range of the light-absorbing material. In the preparation method, the addition amount of the sulfur source can be controlled to control CuCo in the semiconductor heterojunction₂O₄And CuCo₂S₄The ratio of (A) to (B) directly influences the performance of the catalyst, and simultaneously influences the conditions of the sulfurization reaction, such as temperature and time, and influences the substitution of sulfur atoms for CuCo₂O₄Efficiency of mesolattice oxygen; the prepared bifunctional catalyst can be used for photocatalytic degradation of DCF and reduction of Cr (III).

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

FIG. 1 is a schematic view of CuCo according to an embodiment of the present disclosure₂O₄A characterization map of (a); wherein FIGS. 1a-1c are CuCo₂O₄SEM image of (1 d) is CuCo₂O₄EDS image of (a);

FIG. 2 is a schematic view of CuCo according to an embodiment of the disclosure₂O₄@CuCo₂O₄A characterization map of (a); wherein FIGS. 2a-2c are CuCo₂O₄@CuCo₂O₄SEM pictures of (a, b, c), and FIG. 2d shows CuCo₂O₄@CuCo₂O₄EDS map of (a);

FIG. 3 is a schematic view of CuCo according to an embodiment of the disclosure₂O₄、CuCo₂O₄@CuCo₂O₄X-ray diffraction spectrum of (a);

FIG. 4 is a CuCo according to an embodiment of the disclosure₂O₄、CuCo₂S₄@CuCo₂O₄(ii) a diffuse reflectance spectrum of ultraviolet-visible light;

FIG. 5 is a schematic view of CuCo according to an embodiment of the disclosure₂O₄、CuCo₂S₄@CuCo₂O₄(ii) a diffuse reflectance spectrum of ultraviolet-visible light;

FIG. 6 is a diagram illustrating the catalytic degradation effect of a copper-based heterojunction catalyst according to an embodiment of the disclosure; wherein FIG. 6(a) is a graph of the effect of catalysts of different degrees of sulfidation on the catalytic degradation of DCF; 6(b) the photocatalytic reduction effect of the catalysts with different degrees of vulcanization on Cr (VI);

FIG. 7 is a graph showing the effect of different catalyst usage amounts on the catalytic degradation of DCF and Cr (VI) provided by the disclosed embodiment of the present invention; wherein FIG. 7(a) is the effect of catalyst usage on DCF degradation; and 7(b) shows the photocatalytic reduction effect of different catalyst dosage on Cr (VI).

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of systems consistent with certain aspects of the invention, as detailed in the appended claims.

The method aims to solve the problems that the actual catalytic capability of the photocatalyst is far lower than the theoretical value of the photocatalyst in the prior art, the large-scale application of the photocatalytic technology is seriously restricted, and the like. The embodiment provides a copper-based heterojunction catalyst with a structural formula of CuCo₂S₄@CuCo₂O₄. CuCo with copper and cobalt bimetallic active sites₂O₄The material is a semiconductor material, has visible light response, low price, abundant earth reserves and excellent photoelectric property, and is widely used in photocatalysis and photoelectrocatalysis systems. Single CuCo₂O₄When the photocatalyst is used as a photocatalyst, the actual catalytic capacity of the photocatalyst is far less than the theoretical value because photogenerated electrons and holes are easy to recombine. Thus, with CuCo₂O₄The semiconductor with similar structure and energy level matching is of great importance for constructing heterojunction, and ternary metal sulfide CuCo is selected in the embodiment₂S₄Not only with CuCo₂O₄The CuCo crystal has similar crystal structure, energy level matching and better absorption to visible light, and is constructed by the embodiment₂S₄@CuCo₂O₄Can effectively inhibit the recombination of carriers and improve the utilization rate of sunlight.

This embodiment specifically providesA process for preparing the Cu-base heterojunction catalyst features that the solvent-thermal method is used to prepare the hollow spherical CuCo with rich pores₂O₄Then taking sodium sulfide as a sulfur source, and taking part of CuCo in a hydrothermal environment₂O₄In-situ conversion to CuCo₂S₄Form CuCo with tight interface connection₂S₄@CuCo₂O₄Heterojunction, and the double-function catalyst is used for degrading DCF and reducing Cr (III) in a photocatalysis way.

The method comprises the following specific steps: a process for preparing copper-base heterojunction catalyst, wherein the hollow spherical CuCo is prepared₂O₄The following methods can be employed: mixing glycerol and isopropanol to obtain a transparent solution; weighing hexahydrate, cobalt nitrate and copper nitrate trihydrate, pouring the hexahydrate and the cobalt nitrate and the copper nitrate trihydrate into the transparent solution, and dissolving to obtain a pink solution; pouring the pink solution into a high-pressure reaction kettle to react for 8-10h at the temperature of 180-; and (4) cooling to room temperature, pouring out the supernatant, putting the obtained precipitate into a centrifuge tube, washing and drying.

Preparation of Na₂S solution and CuCo₂O₄Mixing, stirring, transferring into a reaction kettle, reacting at the temperature of 120-; then calcining the dried sample in a muffle furnace for 2-3h at the heating rate of 3-5 ℃/min to obtain CuCo₂S₄@CuCo₂O₄A composite material.

The present invention will be further described with reference to the accompanying drawings for more clearly illustrating the technical solutions of the present invention, but they should not be construed as limiting the scope of the present invention.

Example 1

CuCo₂S₄@CuCo₂O₄Preparation of heterojunction composite materials

Transferring 48mL of glycerol (glycerin) and 240mL of isopropanol into a 500mL beaker, and stirring until a clear solution is obtained; 2.3340g of hexahydrate, cobalt nitrate and 3.8706g of copper nitrate trihydrate are weighed by an analytical balance, poured into a transparent solution, and stirred to dissolve to obtain a pink solution; pouring the pink solution into a high-pressure reaction kettle, placing the high-pressure reaction kettle in a forced air drying oven, and reacting for 10 hours at 180 ℃; after cooling to room temperature, the supernatant was poured off, and the obtained precipitate was put into a centrifuge tube, washed with deionized water (5 times) and absolute ethanol (3 times) in sequence, and dried in an air-blast drying oven at 60 ℃.

The measuring cylinder accurately measures 50mL of deionized water in a 100mL beaker. 0.1057g of Na were then accurately weighed out with an analytical balance₂S is added into a beaker, stirred until the S is dissolved, and then 0.25g of prepared CuCo is added₂O₄Stirring for 30min, transferring into a reaction kettle, and reacting for 10h at 120 ℃. After the mixture is cooled to room temperature, the mixture is centrifugally cleaned for three times by deionized water and ethanol respectively, and dried for later use. Calcining the dried sample in a muffle furnace at 350 ℃ for 3h at the heating rate of 3 ℃/min to obtain CuCo₂S₄@CuCo₂O₄A composite material.

Scanning Electron Microscope (SEM) for CuCo₂O₄And CuCo₂S₄@CuCo₂O₄The morphology of (a) is characterized. As shown in FIGS. 1a-1c, CuCo₂O₄Is a mixture of small CuCo₂O₄The diameter of the hollow porous spherical structure assembled by the nano particles is about 400 nm. The photocatalyst has a rough surface, has rich pores and a hollow structure, not only has a large specific surface area and can provide more catalytic active sites, but also is beneficial to the absorption of incident light through multi-level scattering and diffraction, the utilization rate of the catalyst to sunlight is improved, and the catalytic oxidation (reduction) capacity of the photocatalyst is further improved. Furthermore, the characterization by energy spectroscopy (EDS) demonstrated that, in CuCo₂O₄Three elements of Cu, Co and O exist in the alloy.

As shown in FIGS. 2a-2c, is CuCo₂S₄@CuCo₂O₄As shown in SEM picture of (1), using CuCo₂O₄Is used as a substrate material, sodium sulfide is used as a sulfur source, and CuCo is obtained after one-step vulcanization₂S₄@CuCo₂O₄The composite material still maintains the shape of the hollow porous microspheres, but part of CuCo₂O₄Is subjected to Na₂S induces secondary growth, and nano particles are converted into a nano sheet structure. From CuCo₂S₄@CuCo₂O₄The nano-sheet assembled hollow porous microspheres are more beneficial to absorption of incident light, have larger specific surface area and more active sites, and are beneficial to improvement of the photocatalytic capacity of the catalyst. EDS characterization showed that₂S₄@CuCo₂O₄In the composite material, besides Cu, Co and O, S element also appears, and the characteristic peak intensity of the O element is weakened, which shows that CuCo element₂O₄With part of the oxygen atoms being replaced by S atoms, CuCo₂S₄@CuCo₂O₄Composites were successfully prepared.

Using X-ray diffractometer (XRD) to measure CuCo₂O₄And CuCo₂S₄@CuCo₂O₄The crystal structure of (a) is characterized. As shown in FIG. 3, the characteristic diffraction peaks at 19.06 °, 31.34 °, 36.95 °, 38.94 °, 45.03 °, 56.01 °, 59.60 °, and 65.68 ° are assigned to CuCo₂O₄The (111), (220), (311), (222), (400), (422), (511) and (440) crystal planes of (a), and the results demonstrate CuCo₂O₄Was successfully prepared.

In the presence of CuCo₂S₄@CuCo₂O₄Except at 19.06 °, 36.95 °, 38.94 °, 45.03 °, 59.60 °, and 65.68 ° CuCo₂O₄Also appeared at 26.58 deg., 31.27 deg., 49.98 deg., 54.79 deg. and 61.88 deg., respectively attributed to CuCo₂S₄(022) Characteristic diffraction peaks of (113), (115), (044) and (026) crystal planes and no other hetero-peaks appear, indicating CuCo₂O₄Part of oxygen in crystal lattice is successfully replaced by sulfur atom and converted into CuCo₂S₄，CuCo₂S₄@CuCo₂O₄Heterojunction composites are successfully prepared.

FIG. 4 is a graph of UV-visible diffuse reflectance spectroscopy vs. CuCo₂O₄And CuCo₂S₄@CuCo₂O₄The light absorption of (2) was examined. CuCo₂O₄Has better absorption to ultraviolet light and visible light below 600nm, when part of CuCo₂O₄Conversion to CuCo₂S₄Post, CuCo₂S₄@CuCo₂O₄The composite material has enhanced absorption of ultraviolet-visible light, and particularly has obvious absorption of visible light in the 600-800nm wave band. This is due to CuCo₂S₄@CuCo₂O₄The hollow porous microspheres assembled by the nano-sheets are more beneficial to the absorption of incident light through multi-level scattering and diffraction compared with the hollow porous microspheres formed by the accumulation of the nano-particles, and on the other hand, sulfur atoms replace CuCo₂O₄After oxygen in crystal lattice, the valence band position is raised, so that the band gap of the semiconductor is reduced and the spectrum absorption range is widened. The spectral absorption intensity is increased, and the range is widened, so that the quantum efficiency of the catalyst is improved, and the satisfactory photocatalytic capability is shown.

FIG. 5 is a graph of UV-visible diffuse reflectance spectroscopy vs. CuCo₂O₄，CuCo₂S₄And CuCo₂S₄@CuCo₂O₄The light absorption of (2) was examined. CuCo₂O₄Has better absorption to ultraviolet light and visible light below 600 nm. When part of CuCo is present₂O₄Conversion to CuCo₂S₄Post, CuCo₂S₄@CuCo₂O₄The composite material has enhanced absorption of ultraviolet-visible light, and particularly has obvious absorption of visible light in the 600-800nm wave band. This is due to CuCo₂S₄@CuCo₂O₄The hollow porous microspheres assembled by the nano-sheets are more beneficial to the absorption of incident light through multi-level scattering and diffraction compared with the hollow porous microspheres formed by the accumulation of the nano-particles, and on the other hand, sulfur atoms replace CuCo₂O₄After oxygen in crystal lattice, the valence band position is raised, so that the band gap of the semiconductor is reduced and the spectrum absorption range is widened. The spectral absorption intensity is increased, and the range is widened, so that the quantum efficiency of the catalyst is improved, and the satisfactory photocatalytic capability is shown.

Example 2

Showing the effect of different degrees of sulfidation on the catalyst performance, we weighed 0.6341g, 0.3170g, 0.1585g, 0.1057g Na, respectively, in the same synthetic procedure as in example 1₂S preparation of different vulcanizates in solutionCatalysts of degree, respectively named CuCo₂S₄@CuCo₂O₄-1、CuCo₂S₄@CuCo₂O₄-2、CuCo₂S₄@CuCo₂O₄-3、CuCo₂S₄@CuCo₂O₄-4。CuCo₂S₄@CuCo₂O₄-1 of CuCo₂S₄With CuCo₂O₄In a molar ratio of 1:2, CuCo₂S₄@CuCo₂O₄-2 of CuCo₂S₄With CuCo₂O₄1:1, CuCo₂S₄@CuCo₂O₄-3 of CuCo₂S₄With CuCo₂O₄In a molar ratio of 2: 1; CuCo₂S₄@CuCo₂O₄The molar ratio in-4 is 3: 1.

Study of CuCo₂S₄@CuCo₂O₄In this example, anti-inflammatory agents diclofenac sodium (DCF) and heavy metal ion chromium (vi) are selected as targets of photocatalytic oxidative degradation and reduction research, respectively. Accurately transferring 50mL of 10mg/L DCF solution into a reactor, and adding CuCo₂S₄@CuCo₂O₄A catalyst. After adding the catalyst, stirring for half an hour in a magnetic stirrer in the dark, after reaching the adsorption balance, taking and absorbing 5mL of solution by a dropper, centrifuging for 5min at the rotating speed of 5000r/min to separate the solution from the catalyst, and taking supernatant liquid to measure the absorbance. After the end of the measurement, the solution was poured back into the reactor together with the catalyst. Then, the xenon lamp was turned on to start the photocatalytic degradation experiment, and the absorbance of the solution was measured every half hour. And calculating the concentration of the DCF through a standard curve, and calculating the degradation rate of the DCF, wherein the formula is as follows:

in the formula: c₀Initial concentration of solution, C_eIn solution at different catalytic timesThe concentration of (c).

The steps of the chromium (VI) photocatalytic reduction and DCF degradation experiments are consistent, and the chromium (VI) photocatalytic reduction and DCF degradation experiments are only exchanged into Cr with different concentrations⁶⁺(100mL of 20mg/L potassium dichromate solution).

The effect of catalysts with different degrees of sulfidation on the degradation of DCF and the reduction of cr (vi) was experimentally investigated. As shown in FIGS. 6a and 6b, CuCo is used₂O₄When the catalyst is used, the degradation rate of the catalyst on DCF is only 8 percent, and the photocatalytic reduction efficiency on Cr (VI) is only 9.06 percent. This is because pure CuCo₂O₄When the catalyst is used as a catalyst, a photon-generated carrier is easy to recombine in the separation and transfer processes, so that the catalytic performance is reduced. When sodium sulfide is used as a sulfur source, part of CuCo is added₂O₄In situ conversion to CuCo₂S₄Form CuCo₂S₄@CuCo₂O₄After heterojunction, the photocatalytic performance is obviously improved. Then, the catalytic degradation efficiency is reduced due to the fact that most of CuCo₂O₄Converted into CuCo₂S₄The optimum structure of the heterojunction is destroyed, so CuCo is selected in the next embodiment₂S₄@CuCo₂O₄(2: 1) As a catalyst, the photocatalytic degradation reduction study was carried out on DCF and Cr (VI).

After the optimal vulcanization degree of the catalyst is determined, the dosage of the catalyst is considered, and 50mg, 100mg and 200mg are respectively selected for carrying out the experiment of catalytic degradation of DCF. As shown in fig. 7a, the catalytic degradation efficiency becomes high with the increase of the catalyst dosage, when 100mg of the catalyst is added, the degradation rate of DCF can reach 80.6%, while the catalytic effect is not significantly increased by continuously increasing the catalyst dosage to 200mg, so 100mg of the catalyst is selected as the optimal catalyst dosage.

The experiment also examined the effect of the catalyst amount on the photocatalytic reduction effect of cr (vi), as shown in fig. 7b, the photocatalytic reduction efficiency increased with the increase of the catalyst amount. When the dosage of the catalyst is increased to 100mg, the catalytic efficiency has no obvious change, so that 50mg of the catalyst is selected as the optimal dosage to carry out the photocatalytic reduction on the Cr (VI) in consideration of the experimental cost. In 4h, the reduction rate of Cr (VI) reaches 73.33 percent.Description of CuCo₂S₄@CuCo₂The O4 (2: 1) catalyst has better catalytic reduction capability to Cr (VI), and can be used for treating chromium-containing wastewater.

In summary, 100mg of CuCo is used₂S₄@CuCo₂O₄-3 as a catalyst, carrying out photocatalytic degradation on 50mL of 10mg/L DCF for 5 hours, wherein the degradation efficiency can reach 80.6%; the photocatalytic reduction of Cr (VI) is carried out with 50mg of catalyst being the best dosage. Within 4h, the reduction rate of Cr (VI) reaches 73.33 percent. Prove that the prepared CuCo₂S₄@CuCo₂O₄-3 heterojunction composite material can be used as a bifunctional catalyst, has the capability of treating wastewater containing DCF and Cr (VI), and does not produce secondary pollution.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.