阅读说明：本技术 一种石墨烯/硫化铜锌花状微米球超结构可见光催化剂的制备方法 (Preparation method of graphene/copper zinc sulfide flower-like micro-sphere superstructure visible-light-driven photocatalyst ) 是由 朱启安 黎平 杨婷文 张凯旋 于 2020-12-15 设计创作，主要内容包括：本发明提供了一种石墨烯/硫化铜锌花状微米球超结构可见光催化剂的制备方法。它包括如下步骤：(1)在去离子水中加入氧化石墨烯GO、可溶性的锌盐及可溶性的铜盐,超声分散,得混合液A；(2)在混合液A中加入硫脲,搅拌溶解后,得混合液B；(3)在混合液B中加入戴帽剂聚乙二醇600,搅拌均匀,得混合液C；(4)将混合液C在140～180℃下水热处理8～12小时,然后,分离洗涤,干燥后得石墨烯/硫化铜锌花状微米球超结构可见光催化剂。本发明制备的产品复合效果好,抗光腐蚀能力强,比表面积大,光生电子-空穴对容易分离,可见光光催化活性高。该方法具有生产工艺简单、反应参数容易控制、绿色环保、实施成本低等优点。(The invention provides a preparation method of a graphene/copper zinc sulfide flower-shaped micro-sphere superstructure visible-light-driven photocatalyst. It comprises the following steps: (1) adding graphene oxide GO, soluble zinc salt and soluble copper salt into deionized water, and performing ultrasonic dispersion to obtain a mixed solution A; (2) adding thiourea into the mixed solution A, and stirring and dissolving to obtain mixed solution B; (3) adding a capping agent polyethylene glycol 600 into the mixed solution B, and uniformly stirring to obtain a mixed solution C; (4) and carrying out hydrothermal treatment on the mixed solution C at the temperature of 140-180 ℃ for 8-12 hours, then, separating, washing and drying to obtain the graphene/copper zinc sulfide flower-shaped microsphere superstructure visible-light-driven photocatalyst. The product prepared by the invention has good composite effect, strong anti-photo-corrosion capability, large specific surface area, easy separation of photo-generated electron-hole pairs and high visible light photocatalytic activity. The method has the advantages of simple production process, easy control of reaction parameters, environmental protection, low implementation cost and the like.)

1. Preparation method of graphene/copper zinc sulfide flower-like micro-sphere superstructure visible-light-driven photocatalyst expressed as RGO/Zn_xCu_1-xS, wherein x is more than or equal to 0.1 and less than or equal to 0.35, and the preparation method is characterized by comprising the following steps:

(1) adding graphene oxide GO into deionized water, and adding copper zinc sulfide Zn_xCu_1-xThe quantity ratio of the zinc to the copper in S is x (1-x), soluble zinc salt and soluble copper salt are added into the S, and the total dosage of the soluble zinc salt and the soluble copper salt is that Zn is added into each milligram of graphene oxide²⁺And Cu²⁺The total amount of the substances is 0.0320-0.0640 mmol, 1-2 mg of graphene oxide is added into per milliliter of deionized water,carrying out ultrasonic dispersion for 1-3 hours to obtain a mixed solution A;

(2) adding thiourea into the mixed solution A, wherein the amount of the thiourea added is Zn²⁺And Cu²⁺Stirring and dissolving the mixture 2-4 times of the total amount of the substances to obtain a mixed solution B;

(3) adding 20-30 mg of capping agent polyethylene glycol 600 into each milliliter of deionized water into the mixed solution B, and uniformly stirring to obtain mixed solution C;

(4) transferring the mixed solution C into a hydrothermal reaction kettle, and carrying out hydrothermal treatment for 8-12 hours at the temperature of 140-180 ℃; after the reaction is finished, naturally cooling to room temperature, performing centrifugal separation to obtain black precipitates, alternately ultrasonically washing the black precipitates respectively by using deionized water and absolute ethyl alcohol, and drying to obtain the graphene/copper zinc sulfide flower-shaped microsphere superstructure visible-light-induced photocatalyst, namely RGO/Zn_xCu_1-xS。

2. The method for preparing the graphene/copper zinc sulfide flower-like micro-sphere superstructure visible-light-driven photocatalyst as claimed in claim 1, wherein the soluble copper salt is one of copper nitrate, copper chloride or copper sulfate.

3. The method for preparing the graphene/copper zinc sulfide flower-like microsphere superstructure visible-light-driven photocatalyst as claimed in claim 1, wherein the soluble zinc salt is one of zinc chloride, zinc sulfate or zinc nitrate.

Technical Field

The invention relates to preparation of a composite material, in particular to a method for preparing a graphene/copper zinc sulfide flower-shaped micron sphere superstructure visible-light-driven photocatalyst by adopting a hydrothermal method.

Background

Along with industrialization and urbanization of all countries in the world, energy crisis and environmental pollution become more serious day by day, the photocatalyst is used for removing toxic and non-biodegradable environmental pollutants in air and wastewater, the pollutants can be thoroughly degraded into non-toxic and harmless inorganic micromolecules, and the method has the advantages that solar energy can be fully utilized, and the catalyst can be recycled.

Conventional TiO₂The photocatalyst is concerned by people because of the advantages of strong oxidizing ability, stable chemical property, no toxicity, high photocatalytic activity and the like, but the relatively wide band gap (3.2eV) can inhibit the spectral response range of the photocatalyst, and only ultraviolet light with the wavelength of less than 387nm can be excited to generate a photocatalytic effect, but the ultraviolet light only accounts for a little part of sunlight, and the rapid recombination of a photo-generated electron-hole pair also limits the photocatalytic efficiency and hinders the practical application of the photocatalyst. Therefore, it is very important to research a novel visible light photocatalytic material with strong visible light absorption capability, good electron-hole pair separation effect and high photocatalytic efficiency.

CuS is used as an important p-type semiconductor material and has high absorption capacity to visible light. However, CuS has the defects of easy recombination of photo-generated electron-hole pairs and poor stability to light, which hinders the practical application of CuS in the field of photocatalysis, but can be doped with other metal ions to prepare multi-metal sulfideThe stability of the product is improved. Therefore, the invention overcomes the defects of CuS in photocatalytic application by two methods, and tries to avoid using a large amount of organic solvent so as to improve the environmental protection and realize the control of cost, and one is to compound the CuS and graphene so as to improve the separation effect of photo-generated electron-hole pairs; secondly, doping Zn into CuS²⁺Preparing a multi-element metal sulfide Zn_xCu_1-xS to improve its stability.

Due to Zn²⁺And Cu²⁺With similar ionic radii (Zn)²⁺And Cu²⁺Respectively has an ionic radius ofAnd) If Zn is added to CuS²⁺，Zn²⁺Namely, can replace Cu in hexagonal phase CuS crystal²⁺To form a substitutional solid solution Zn_xCu_1-xS (copper zinc sulfide), which not only can improve the stability of CuS, but also can improve the energy band gap (the absorption of light is still in the visible light range) of CuS, so that the CuS has stronger oxidative degradation capability on pollutants. In addition, due to Zn²⁺Has a Lowest Unoccupied Molecular Orbital (LUMO) energy level higher than that of Cu²⁺，Zn²⁺Can be used as a shallow electron trap and can improve Zn_xCu_1-xThe life of photogenerated electrons and holes in the S nanocrystal, so that the photocatalytic efficiency of the S nanocrystal is improved.

Graphene is a novel two-dimensional (2D) carbon material, and is receiving attention due to its unique properties such as a large specific surface area, high electrical conductivity, and excellent thermal conductivity. It possesses high electron mobility (200000 cm) due to its conjugated large pi bond, which makes electrons easy to move freely²·V^-1·s^-1) The method can construct an optimized transmission path of the photo-generated electrons across the interface of the composite material, thereby inhibiting the recombination of the photo-generated electron-hole pairs and improving the photocatalytic activity of the semiconductor material. Secondly, the graphene serving as a matrix for uniformly dispersing the semiconductor particles can ensure the composite photocatalystLarge specific surface area to provide more reaction sites, resulting in increased photocatalytic activity.

The graphene/copper sulfide zinc flower-shaped micron sphere superstructure visible light catalyst is prepared by a hydrothermal method by using Graphene Oxide (GO), thiourea (Tu), soluble zinc salt and copper salt as raw materials, polyethylene glycol 600(PEG600) as a capping agent and water as a solvent. During the reaction, Cu²⁺Form complexes with thiourea first [ but Zn²⁺Very weak complexing power with thiourea, Cu (Tu)₂ ²⁺And Zn (Tu)₂ ²⁺Respectively, are 2.51X 10¹⁵And 59]Now positively charged Cu (Tu)₂ ²⁺、Zn²⁺[ including the formation of a small amount of unstable Zn (Tu)₂ ²⁺]Adsorbing onto a layer of negatively charged graphene sheets, and then, under the conditions of hydrothermal reaction, Cu (Tu)₂ ²⁺Decompose to form hexagonal CuS crystal nuclei (the solubility product constant of ZnS is much larger than that of CuS, and thus no ZnS crystal nuclei are formed) due to Zn²⁺ And Cu²⁺ Radius of (2) is similar, in the crystal growth process, Zn²⁺Then the crystal lattice of the hexagonal phase CuS is partially substituted for Cu²⁺To form a substitutional solid solution Zn_xCu_1-xAnd S, preferentially growing the nano-sheets (hexagonal crystals are easy to form sheet-shaped appearances). And because the nano sheet has large specific surface area, high specific surface free energy, instability and Zn_xCu_1-xThe S nano-sheets are gathered together and self-assembled into flower-shaped microspheres to reduce the surface free energy of the flower-shaped microspheres so as to achieve a stable state. In addition, the added capping agent polyethylene glycol 600 can be selectively adsorbed on certain interfaces of crystal growth to control the growth rate of crystal faces and prevent the agglomeration of crystals, and is also favorable for forming Zn which has good appearance and good dispersibility and is formed by nanosheets_xCu_1-xS-shaped flower-shaped micro-spheres. During the reaction, graphene oxideReduced to graphene (RGO), graphene and Zn by thiourea_xCu_1-xCompounding S micron spheres to obtain graphene/copper zinc sulfide flower-like micron spheres (RGO/Zn)_xCu_1-xS(0.1≤x≤0.35)]A composite photocatalyst is provided. Due to Zn_xCu_1-xThe composition of S and graphene can utilize the characteristics of high electron mobility and strong conductivity of graphene to promote the separation of photo-generated electron-hole pairs and improve the photocatalytic efficiency of the photo-generated electron-hole pairs. Meanwhile, due to the doping of Zn in the CuS²⁺Preparing the multi-element metal sulfide Zn_xCu_1-xS, the stability is improved, and the photo-corrosion is inhibited. The result of investigating the visible light photocatalytic performance of the composite photocatalyst shows that the product not only has higher visible light photocatalytic activity, can fully utilize sunlight to carry out photocatalytic degradation on environmental pollutants, but also has strong anti-light corrosion capability and high stability.

Disclosure of Invention

The invention aims to provide a preparation method of a graphene/copper zinc sulfide flower-like micro-sphere visible light photocatalyst which is green and environment-friendly, takes water as a solvent, is low in cost, simple in process, good in material compounding effect, high in product stability and high in visible light photocatalytic activity.

The purpose of the invention is realized by the following steps:

a graphene/copper zinc sulfide flower-like micro-sphere superstructure visible-light-induced photocatalyst is represented by RGO/Zn_xCu_1-xS, wherein x is more than or equal to 0.1 and less than or equal to 0.35, and the preparation method comprises the following steps:

(1) adding graphene oxide GO into deionized water, and then adding copper zinc sulfide Zn_xCu_1-xThe quantity ratio of the zinc to the copper in S is x (1-x), soluble zinc salt and soluble copper salt are added into the S, and the total dosage of the soluble zinc salt and the soluble copper salt is that Zn is added into each milligram of graphene oxide²⁺And Cu²⁺The total amount of the substances is 0.0320-0.0640 mmol, 1-2 mg of graphene oxide is added into deionized water per milliliter, and ultrasonic dispersion is carried out for 1-3 hours to obtain a mixed solution A;

(2) adding thiourea into the mixed solution A, and adding the thiourea into the mixed solution AIn an amount of Zn²⁺And Cu²⁺Stirring and dissolving the mixture 2-4 times of the total amount of the substances to obtain a mixed solution B;

(3) adding 20-30 mg of capping agent polyethylene glycol 600 into each milliliter of deionized water into the mixed solution B, and uniformly stirring to obtain mixed solution C;

(4) transferring the mixed solution C into a hydrothermal reaction kettle, and carrying out hydrothermal treatment for 8-12 hours at the temperature of 140-180 ℃; after the reaction is finished, naturally cooling to room temperature, performing centrifugal separation to obtain black precipitates, alternately ultrasonically washing the black precipitates respectively by using deionized water and absolute ethyl alcohol, and drying to obtain the graphene/copper zinc sulfide flower-shaped microsphere superstructure visible-light-induced photocatalyst, namely RGO/Zn_xCu_{1- x}S。

Further, the soluble copper salt is one of copper nitrate, copper chloride or copper sulfate.

Further, the soluble zinc salt is one of zinc chloride, zinc sulfate or zinc nitrate.

The invention has the beneficial effects that:

(1) the graphene/copper zinc sulfide flower-shaped microsphere superstructure visible-light-driven photocatalyst is prepared by a hydrothermal method, and the method has the advantages of simple production process, easiness in control of reaction parameters, low implementation cost and the like. And because water is used as the solvent, the use of a large amount of organic solvent is avoided, the production cost is reduced, and the environment-friendly concept of green chemistry is met.

(2) The graphene/copper zinc sulfide flower-shaped micro-sphere superstructure visible-light-driven photocatalyst prepared by the invention has the following advantages: the absorption capacity to visible light is strong; easy separation of the photoproduction electron-hole pairs; the specific surface area of the catalyst is large; doping Zn in hexagonal phase CuS²⁺The energy band gap is improved, the oxidative degradation capability of the copper sulfide zinc on pollutants is improved, and the prepared copper sulfide zinc sulfide has strong light corrosion resistance. Therefore, the composite photocatalyst has high visible light photocatalytic activity and high stability, can fully utilize solar energy to carry out photocatalytic degradation on environmental pollutants, and has high efficiency and low cost.

Drawings

Fig. 1 is an X-ray diffraction (XRD) pattern of the graphene/copper zinc sulfide flower-like microsphere superstructure visible-light-induced photocatalyst prepared in example 1.

Fig. 2 and 3 are Scanning Electron Microscope (SEM) images of graphene/copper zinc sulfide flower-like microsphere superstructures prepared in example 1 at magnifications of 5000 (fig. 2) and 15000 (fig. 3), respectively.

Fig. 4 and 5 are Scanning Electron Microscope (SEM) images of the graphene/copper zinc sulfide prepared in comparative example 1 without addition of capping agent polyethylene glycol 600 at magnifications of 5000 (fig. 4) and 15000 (fig. 5), respectively.

Fig. 6 is a Scanning Electron Microscope (SEM) image of copper zinc sulfide prepared in comparative example 2 without Graphene Oxide (GO).

FIG. 7 is a diagram showing the photocatalytic degradation effect of the product. Wherein e is the graphene/copper zinc sulfide prepared in comparative example 1, f is the copper zinc sulfide prepared in comparative example 2, a, b, c and d are the graphene/copper zinc sulfide flower-like microsphere superstructure visible-light-driven photocatalyst prepared in example 1, example 2, example 4 and example 3 respectively, the abscissa represents the degradation time, and the ordinate represents the degradation rate.

Detailed Description

The invention is further illustrated by the following examples, without restricting its scope by the examples given.

Example 1

(1) Adding 120mg of graphene oxide GO and 0.414g of ZnSO into 75mL of deionized water₄·7H₂O and 0.573g of CuCl₂·2H₂O (equivalent to 1.6mg of graphene oxide per ml of deionized water, and Zn per mg of graphene oxide²⁺And Cu²⁺In an amount of 0.0400mmol of the total of the components, in which Zn²⁺0.0120mmol, Cu²⁺0.0280mmol, x ═ 0.3), and ultrasonic dispersion was carried out for 2 hours to obtain a mixed solution a;

(2) to the mixture A was added 1.096g of thiourea (the amount of the substance is Zn)²⁺And Cu²⁺3 times of the total substance), stirring and dissolving to obtain a mixed solution B;

(3) adding 2.00g of capping agent polyethylene glycol 600 (the dosage of which is 26.7mg per ml of deionized water) into the mixed solution B, and uniformly stirring to obtain mixed solution C;

(4) transferring the mixed solution C into a hydrothermal reaction kettle, and carrying out hydrothermal treatment for 10 hours at the temperature of 150 ℃; after the reaction is finished, naturally cooling to room temperature, centrifugally separating to obtain black precipitates, alternately ultrasonically washing the black precipitates by deionized water and absolute ethyl alcohol respectively, and drying to obtain RGO/Zn_0.3Cu_0.7S flower-shaped microsphere superstructure visible-light-driven photocatalyst product.

Example 2

(1) Adding 105mg of graphene oxide GO and 0.125g of ZnCl into 75mL of deionized water₂And 0.928g Cu (NO)₃)₂·3H₂O (equivalent to 1.4mg of graphene oxide per ml of deionized water, and Zn per mg of graphene oxide²⁺And Cu²⁺In an amount of 0.0457mmol of total species, wherein Zn²⁺0.0091mmol, Cu²⁺0.0366mmol, x is 0.2), ultrasonic dispersion is carried out for 3 hours, and mixed liquor A is obtained;

(2) 0.730g of thiourea (Zn in terms of the amount of the substance) was added to the mixed solution A²⁺And Cu²⁺2 times of the total substance), stirring and dissolving to obtain a mixed solution B;

(3) adding 2.10g of capping agent polyethylene glycol 600 (the dosage of the capping agent polyethylene glycol 600 is 28mg per ml of deionized water) into the mixed solution B, and uniformly stirring to obtain mixed solution C;

(4) transferring the mixed solution C into a hydrothermal reaction kettle, and carrying out hydrothermal treatment for 11 hours at 160 ℃; after the reaction is finished, naturally cooling to room temperature, centrifugally separating to obtain black precipitates, alternately ultrasonically washing the black precipitates by deionized water and absolute ethyl alcohol respectively, and drying to obtain RGO/Zn_0.2Cu_0.8S flower-shaped microsphere superstructure visible-light-driven photocatalyst product.

Example 3

(1) Add 150mg graphene oxide GO, 0.500g Zn (NO) to 75mL deionized water₃)₂·6H₂O and 0.779g CuSO₄·5H₂O (equivalent to 2mg of graphene oxide per ml of deionized water and Zn per mg of graphene oxide²⁺And Cu²⁺In an amount of 0.0320mmol, wherein Zn²⁺0.0112mmol, Cu²⁺0.0208mmol, x is 0.35), ultrasonic dispersion is carried out for 3 hours, and mixed liquor A is obtained;

(2) 1.459g of thiourea (the amount of the substance is Zn) was added to the mixed solution A²⁺And Cu²⁺4 times of the total substance), stirring and dissolving to obtain a mixed solution B;

(3) adding 1.50g of capping agent polyethylene glycol 600 (20 mg per ml of deionized water) into the mixed solution B, and uniformly stirring to obtain mixed solution C;

(4) transferring the mixed solution C into a hydrothermal reaction kettle, and carrying out hydrothermal treatment for 8 hours at 180 ℃; after the reaction is finished, naturally cooling to room temperature, centrifugally separating to obtain black precipitates, alternately ultrasonically washing the black precipitates by deionized water and absolute ethyl alcohol respectively, and drying to obtain RGO/Zn_0.35Cu_0.65S flower-shaped microsphere superstructure visible-light-driven photocatalyst product.

Example 4

(1) 75mg of graphene oxide GO and 0.138g of ZnSO are added into 75mL of deionized water₄·7H₂O and 0.736g of CuCl₂·2H₂O (equivalent to 1mg of graphene oxide per ml of deionized water and Zn per mg of graphene oxide²⁺And Cu²⁺In an amount of 0.0640mmol of the total substances, wherein Zn²⁺0.0064mmol, Cu²⁺0.0576mmol, x is 0.1), ultrasonic dispersion is carried out for 1 hour, and mixed liquor A is obtained;

(2) 0.730g of thiourea (Zn in terms of the amount of the substance) was added to the mixed solution A²⁺And Cu²⁺2 times of the total substance), stirring and dissolving to obtain a mixed solution B;

(3) adding 2.25g of capping agent polyethylene glycol 600 (30 mg per ml of deionized water) into the mixed solution B, and uniformly stirring to obtain mixed solution C;

(4) transferring the mixed solution C into a hydrothermal reaction kettle, and carrying out hydrothermal treatment for 12 hours at the temperature of 140 ℃; after the reaction is finished, naturally cooling to room temperature, centrifugally separating to obtain black precipitates, alternately ultrasonically washing the black precipitates by deionized water and absolute ethyl alcohol respectively, and drying to obtain RGO/Zn_0.1Cu_0.9S flower-shaped microsphere superstructure visible-light-driven photocatalyst product.

Comparative example 1

Except that the capping agent polyethylene glycol 600 is not added, the graphene/copper zinc sulfide is prepared by the same method for preparing the composite material, so that the morphology and the photocatalytic performance of the obtained product and the graphene/copper zinc sulfide flower-shaped micron sphere superstructure visible-light-induced photocatalyst prepared in the embodiments 1, 2, 3 and 4 are compared and researched, and the method specifically comprises the following steps:

(1) adding 120mg of graphene oxide GO and 0.414g of ZnSO into 75mL of deionized water₄·7H₂O and 0.573g of CuCl₂·2H₂O (equivalent to 1.6mg of graphene oxide per ml of deionized water, and Zn per mg of graphene oxide²⁺And Cu²⁺In an amount of 0.0400mmol of the total of the components, in which Zn²⁺0.0120mmol, Cu²⁺0.0280mmol, x ═ 0.3), and ultrasonic dispersion was carried out for 2 hours to obtain a mixed solution a;

(2) to the mixture A was added 1.096g of thiourea (the amount of the substance is Zn)²⁺And Cu²⁺3 times of the total substance), stirring and dissolving to obtain a mixed solution B;

(4) transferring the mixed solution B into a hydrothermal reaction kettle, and carrying out hydrothermal treatment for 10 hours at the temperature of 150 ℃; after the reaction is finished, naturally cooling to room temperature, centrifugally separating to obtain black precipitates, alternately ultrasonically washing the black precipitates by deionized water and absolute ethyl alcohol respectively, and drying to obtain RGO/Zn_0.3Cu_0.7S。

Comparative example 2

In order to compare and research the photocatalytic performance of graphene/copper zinc sulfide flower-shaped micro spherical superstructure and copper zinc sulfide, except that Graphene Oxide (GO) is not added, the copper zinc sulfide is prepared by the same method for preparing the composite material, and the method comprises the following specific steps:

(1) 0.414g of ZnSO was added to 75mL of deionized water₄·7H₂O and 0.573g of CuCl₂·2H₂O, ultrasonic dispersion is carried out for 2 hours to obtain mixed liquor A;

(2) to the mixture A was added 1.096g of thiourea (the amount of the substance is Zn)²⁺And Cu²⁺3 times of the total substance), stirring and dissolving to obtain a mixed solution B;

(3) adding 2.00g of polyethylene glycol 600 (the dosage of which is 26.7mg per ml of deionized water) as a capping agent into the mixed solution B, and uniformly stirring to obtain mixed solution C;

(4) transferring the mixed solution C into a hydrothermal reaction kettle, and carrying out hydrothermal treatment for 10 hours at the temperature of 150 ℃; after the reaction is finished, naturally cooling to room temperature, centrifugally separating to obtain black precipitates, alternately ultrasonically washing the black precipitates by deionized water and absolute ethyl alcohol respectively, and drying to obtain Zn_0.3Cu_0.7S。

Visible light photocatalytic performance test:

0.1g of photocatalyst was added to 100mL of 20mg/L Methylene Blue (MB) solution, and then 2.4mL of 30% by mass H was added₂O₂Ultrasonically dispersing for 5 minutes in the dark, and magnetically stirring for 30 minutes in the dark to ensure that methylene blue reaches adsorption equilibrium on the surface of the catalyst. After 5mL of sample liquid is centrifugally separated to remove the catalyst powder, the absorbance of the sample liquid at 664nm (the maximum absorption wavelength of methylene blue) is tested by using an ultraviolet-visible spectrophotometer and is taken as the initial absorbance A of the degraded liquid₀. Then, a 35W xenon lamp (lumen degree 3200Lm, color temperature 6000K) is used as a light source to carry out a visible light photocatalytic degradation experiment (the top end of the xenon lamp is 15cm away from the liquid surface), magnetic stirring is carried out simultaneously, 5mL of sample liquid is taken every 5 minutes, after 5mL of catalyst solid is removed by centrifugal separation, supernatant liquid is taken to test the absorbance A of the supernatant liquid at the same wavelength_xAnd calculating the degradation rate of the methylene blue solution according to the degradation rate.

Taking example 1 as an example, the X-ray diffraction (XRD) spectrum of the product obtained by the invention is shown in figure 1 (the X-ray diffraction spectra of the products obtained in examples 1 to 4 are basically consistent). In fig. 1, except that the diffraction peak at 2 θ ═ 23.2 ° is that of graphene, all other diffraction peaks match with the standard spectrum of hexagonal phase CuS (JCPDS No.78-0876), and there is no ZnS diffraction peak, because Zn is present²⁺ And Cu²⁺ Doped Zn with similar ionic radius²⁺Will partially replace Cu in CuS²⁺Form a hexagonal phase of a substituted solid solution Zn_0.3Cu_0.7S, thereby enabling Zn_0.3Cu_0.7S has the same hexagonal phase crystal structure as CuS, and the product does not contain ZnS impurities. In addition, as can be seen from FIG. 1, the strongest diffraction peak of copper zinc sulfide is in the (110) crystal plane, while the strongest diffraction peak of standard card JCPDS No.78-0876 is in the (103) crystal plane, which indicates that the preferred orientation of the nanosheet is changed due to anisotropic growth of the nanosheet.

Taking example 1 as an example, Scanning Electron Microscope (SEM) images of the product obtained by the present invention are shown in fig. 2 and 3. As can be seen from FIGS. 2 and 3, Zn in the product_0.3Cu_0.7The S-flower-shaped microsphere superstructure is uniformly loaded on the surface of the graphene sheet layer or inserted between the graphene sheet layers, the graphene sheet layer and the S-flower-shaped microsphere superstructure can be well compounded, the surface of the graphene sheet layer is smooth, has special wrinkles, is thin and transparent, has good light transmittance, and can clearly see Zn below the sheet layer_0.3Cu_0.7The S-shaped flower-shaped micro-sphere superstructure is round in flower-shaped micro-sphere shape, perfect in appearance, 2.4-5.9 mu m (micrometer) in diameter, and is formed by cross assembly of nanosheets which are smooth in surface, regular in appearance and 46-78 nm (nanometer) in thickness.

FIGS. 4 and 5 are Scanning Electron Microscope (SEM) images of graphene/copper zinc sulfide prepared by the same method for preparing the composite material without adding the capping agent polyethylene glycol 600 in the comparative example 1, and as can be seen from FIGS. 4 and 5, the overall morphology of the graphene/copper zinc sulfide prepared by adding the capping agent polyethylene glycol 600 is not constituted by nanosheets (as can be clearly seen by direct comparison of FIGS. 3 and 5, the microspheres obtained in FIG. 3 are formed by cross-assembling regular nanosheets), but consists of a plurality of disordered and uneven-thickness particles with fracture in the middle, the distance between the particles is very close, the whole micron sphere also has the tendency of changing into solid micron particles, the diameter of the graphene is 2.2-6.1 micrometers (microns), and some micron balls are independently agglomerated together and are not well compounded with graphene. Therefore, the capping agent polyethylene glycol 600 has important influence on the shape and the composite effect of the final copper zinc sulfide.

FIG. 6 is a Scanning Electron Microscope (SEM) image of copper zinc sulfide prepared in comparative example 2, and it can be seen from FIG. 6 that Zn is prepared without addition of graphene oxide_0.3Cu_0.7The S-shaped micron spheres have smaller diameter, uneven size and serious agglomeration, and the diameter of the S-shaped micron spheres is 1.4-2.8 microns (microns). The nano-sheets forming the microspheres have rough surfaces and uneven thickness, are not spread, and have closer distance between the sheets, so that the flower-shaped microsphere superstructure tends to become a solid microsphere. Therefore, the graphene also has an important influence on the morphology of the copper zinc sulfide.

The photocatalytic degradation effect is shown in fig. 7. As can be seen from fig. 7, the photocatalytic degradation rate of methylene blue is reduced in the order of a, b, c, d, e, and f (as shown by arrows in the figure), the photocatalytic degradation effect of copper zinc sulfide (f, corresponding to comparative example 2) is the worst, and then the graphene/copper zinc sulfide composite material (e, corresponding to comparative example 1) prepared without adding PEG600 has a significantly lower photocatalytic degradation efficiency than the graphene/copper zinc sulfide flower-like microsphere superstructure products (corresponding to a, b, c, and d, respectively) prepared in examples 1, 2, 4, and 3, while the visible photocatalytic activity of the photocatalyst (a) obtained in example 1 is the highest, and the degradation rate of methylene blue can reach 99.96% after 60 minutes of 35W xenon lamp degradation.