Hollow nanocage CoSx / In2S3 heterojunction and preparation method and application thereof

Abstract

The invention discloses a hollow nanocage CoS < x > / In2S3 heterojunction and a preparation method and application thereof. The preparation method of the heterojunction comprises the following steps: 1) in a methanol solution, combining a Co < 2 + > source with 2-methylimidazole at room temperature to obtain a ZIF-67 regular polyhedron; (2) vulcanizing the ZIF-67 regular polyhedron into a CoSx hollow nanocage by a simple solvothermal method of thioacetamide at 120 to 180 DEG C; and (3) loading the In2S3 on the CoSx through a constant-temperature oil bath method at the temperature of 75-90 DEG C to form the layered hollow nanocage CoSx / In2S3 heterojunction coated with the In2S3 nanosheet. The simple chemical synthesis method is adopted, energy consumption is lower, and the prepared compound CoSx / In2S3 is better in uniformity and shows excellent photocatalytic degradation activity.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro-nano composite material synthesis, and particularly relates to hollow nano cage CoS x / In2S3 heterojunction and its preparation method and application. Background Art

[0002] Photocatalytic technology is considered to be a promising method to solve water pollution problems due to its simplicity, low energy consumption, high conversion efficiency, no pollution and recyclability, and its wide range of applications in converting various organic pollutants into non-polluting inorganic substances (such as H2O and CO2).

[0003] CN110586160A discloses a method for preparing a caged cobalt sulfide graphite phase carbon nitride Z-type heterojunction composite photocatalyst, wherein ultrathin graphite phase carbon nitride nanosheets are prepared by calcining twice; ZIF-67 is used as a template, a sulfur source is introduced, and calcination is performed in an inert gas atmosphere to obtain a caged cobalt sulfide; the graphite phase carbon nitride nanosheets are coated on the surface of the caged cobalt sulfide to prepare a caged cobalt sulfide / graphite phase carbon nitride composite photocatalyst. The composite photocatalyst prepared can efficiently and quickly remove tetracycline compounds from water under visible light, and exhibits good stability and catalytic performance. However, this method requires two calcination processes, and the calcination temperature is high, resulting in large energy consumption; although the prepared composite photocatalyst shows a certain effect in removing tetracycline compounds, the improvement of the photocatalytic degradation rate is limited.

[0004] In view of the above-mentioned shortcomings, how to further improve the photocatalytic degradation rate of organic pollutants and explore simpler and lower-energy preparation methods has become a key issue that needs to be urgently addressed in the current field of photocatalytic technology. Summary of the invention

[0005] In view of the great potential of photocatalytic technology in treating water pollution and the limited improvement of photocatalytic degradation rate of existing catalysts, the present invention aims to propose an innovative solution. The core purpose of the present invention is to synthesize CoS derived from ZIF-67 through a simple chemical synthesis method. x Composited with In2S3 to construct a heterojunction CoS with excellent photocatalytic performance x / In2S3 (abbreviated as CoIS) and applied to photocatalytic degradation of organic pollutants.

[0006] The idea of ​​the invention is: in the design and construction of the heterojunction, a two-phase photocatalyst with a matching energy band structure is used to form a potential gradient, thereby promoting the separation and conversion of photoinduced charges and improving the photocatalytic efficiency. At the same time, the close contact between the two phases of the heterojunction shortens the photogenerated charge transfer path, establishes a fast electron transfer channel, is conducive to the photoexcited charge separation, and thus improves the interface charge carrier separation and transfer efficiency. Specifically, the metal sulfide-based heterojunction composite material constructed by the present invention not only exhibits a wider visible light absorption range, but also greatly suppresses the recombination of photogenerated charges. On the other hand, the heterojunction is designed as a hollow structure with a unique 3D hierarchical structure. This morphology structure not only provides more reactive centers for the photocatalytic reaction, but also has a higher specific surface area. The high specific surface area provides more active sites. In terms of preparation method, a simple chemical synthesis method is adopted, which has lower energy consumption and better uniformity.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a hollow nano cage CoS x The method for preparing a / In2S3 heterojunction comprises the following steps:

[0009] 1) In methanol solution, Co 2+ The source was combined with 2-methylimidazole at room temperature to obtain a regular polyhedron of ZIF-67;

[0010] 2) The ZIF-67 regular polyhedron was sulfurized into CoS by a simple solvothermal method with thioacetamide at 120-180 °C. x Hollow nanocages;

[0011] 3) In2S3 is loaded on CoS by a constant temperature oil bath method at 75-90°C. x On the surface, a layered hollow nanocage CoSx / In2S3 heterojunction coated with In2S3 nanosheets is formed.

[0012] Furthermore, the specific steps of obtaining the ZIF-67 regular polyhedron in step 1) are: adding Co 2+ The source and 2-methylimidazole are dissolved in CH3OH respectively to obtain dispersion A and dispersion B. Dispersion A is quickly poured into dispersion B and then allowed to stand. The solid product is separated by centrifugation or filtration, washed several times with 2-methylimidazole, and dried to obtain ZIF-67 regular polyhedrons. It is preferred to stand for 24 hours to obtain ZIF-67 regular polyhedrons with a particle size of 400-500nm. Standing for less than 24 hours can obtain ZIF-67 regular polyhedrons with smaller particle sizes, but smaller particle sizes are not conducive to the subsequent deposition of In2S3 nanosheets; the Co 2+The source is cobalt nitrate or cobalt nitrate hydrate.

[0013] Preferably, the Co 2+ The source is Co(NO3)2·5H2O. Co such as CoCl2 and Co(CO3)2 2+ source, it is impossible to obtain a ZIF-67 regular polyhedron with a morphological structure that meets the requirements.

[0014] Step 2) ZIF-67 regular polyhedron is sulfurized into CoS x The specific steps include: dispersing ZIF-67 regular polyhedrons in ethanol, then dropping an ethanol solution in which thioacetamide is dissolved, transferring to an autoclave and heating at 120-180°C for 3-4 hours, then washing and drying to obtain black CoS x Hollow nanocages; wherein the weight ratio of ZIF-67 regular polyhedrons to thioacetamide is between 0.5 and 2. As the number of ZIF-67 regular polyhedrons decreases, the prepared CoSx becomes thinner and thinner. When the above weight ratio is less than 0.5, the prepared CoSx shell is more damaged.

[0015] In step 2), it is preferred to use 120°C thioacetamide for solvent thermal reaction to obtain CoS with the most uniform loading of In2S3 and the most uniform and stable morphology. x Hollow nanocages.

[0016] The synthesis method of In2S3 is: using thioacetamide (TAA, CH3CSNH2) as a sulfur source, In2S3 is synthesized by the following reaction:

[0017] CH3CSNH2+H2O=CH3CONH2+H2S(1)

[0018] 2In 3+ +3H2S=In2S3+6H + (2)

[0019] In step 3), In2S3 is loaded on CoS x The specific steps include: x The hollow nanocages were dissolved in a mixed solution of deionized water and glycerol, and In 3+ The source and thioacetamide are added, and then subjected to ultrasonication and / or stirring, and then placed in a constant temperature oil bath at 75-90°C for 1-3 hours, and then cooled, cleaned and dried to obtain CoS x / In2S3 heterojunction; control In 3+ In source and thioacetamide 3+ and S 2- The molar ratio is 2:3, In 3+ and CoS xThe molar mass ratio of the hollow nanocage is 0.25 mol:(5.6-16.8) g. Preferably, in the mixed solution of deionized water and glycerol, the volume ratio of deionized water to glycerol is 4:1. The volume ratio of the dispersed CoS x Hollow nanocages are more conducive to the uniform and stable loading of In2S3 nanosheets.

[0020] As an example, the In 3+ The source is indium chloride or indium chloride hydrate, such as indium chloride tetrahydrate.

[0021] In a second aspect, the present invention provides a hollow nanocage CoS prepared by the method described in the first aspect. x / In2S3 heterojunction.

[0022] In a third aspect, the present invention further provides the heterojunction described in the second aspect for use in photocatalytic degradation of organic pollutants in an aqueous environment.

[0023] By way of example, organic contaminants include tetracycline hydrochloride.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. Compared with the corresponding monomers CoSx and In2S3, the composite CoSx / In2S3 exhibits excellent photocatalytic degradation activity. The experimental results show that the composite sample CoSx / In2S3 exhibits excellent photocatalytic performance and good stability under the synergistic effect of morphology regulation.

[0026] 2. The present invention adopts a simple chemical synthesis method with lower energy consumption, and the prepared composite CoSx / In2S3 has better uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the preparation process of CoSx / In2S3 heterojunction in Example 1 of the present invention;

[0028] Figure 2 This is a schematic diagram of the structure of the hollow nanocage CoSx / In2S3 of the present invention;

[0029] Figure 3 is a scanning electron microscope image of CoSx prepared in Example 1 of the present invention;

[0030] Figure 4 is a transmission electron microscope image of CoSx prepared in Example 1 of the present invention;

[0031] Figure 5 This is a scanning electron microscope image of the hollow nanocage CoSx / In2S3 of Example 1 of the present invention;

[0032] Figure 6 This is a transmission electron microscope image of the hollow nanocage CoSx / In2S3 of Example 1 of the present invention;

[0033] Figure 7 This is the XRD picture of the standard diffraction pattern of the hollow nanocage CoSx / In2S3 prepared in Example 1 of the present invention, indicating that it is CoSx / In2S3;

[0034] Figure 8 is a graph of TCH of photocatalytic degradation of CoSx / In2S3 (CoIS) in Example 1;

[0035] Fig. 9 This is the degradation rate diagram of TCH photocatalytic degradation by CoSx / In2S3 (CoIS) in Example 1. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Chemical raw materials used in the preparation: cobalt nitrate hexahydrate (Co(NO3)2·6H2O), methanol (CH3OH), thioacetamide (TAA), ethanol (C2H5OH) and glycerol (GL) were provided by Sinopharm Chemical Reagent Company, and 2-methylimidazole (C4H6N2) and indium chloride tetrahydrate (InCl3·4H2O) were purchased from Aladdin Reagent Co., Ltd. All chemicals were obtained from commercial suppliers and used directly without further purification.

[0038] Characterization of the prepared and synthesized samples using the following instrument: The crystal structure of the prepared samples was characterized by a Burker D8 (Germany) X-ray diffractometer (XRD) with an incident source in the range of 2θ = 10-80° at room temperature. The microscopic morphology and structure of the samples were characterized by a JEM-F200 (Japan) transmission electron microscope (TEM). The ultraviolet-visible diffuse reflectance spectrum (UV-vis DRS) was measured on a PuXinTU-1901 ultraviolet-visible spectrophotometer with an integrating sphere in the wavelength range of 200-800nm.

[0039] Example 1

[0040] See also Figure 1 The present invention proposes a hollow nanocage CoSx The method for preparing a / In2S3 heterojunction comprises the following steps:

[0041] (1) First, 4 mmol of Co(NO3)2·5H2O and 16 mmol of C4H6N2 were dissolved in CH3OH solution, and the Co(NO3)2·5H2O dispersion was quickly poured into the C4H6N2 dispersion and then allowed to stand for 24 h. The solid product was separated by centrifugation or filtration, washed several times with C4H6N2, and finally dried in an oven at 60 °C overnight. The purple powder was the ZIF-67 regular polyhedron.

[0042] (2) First, 0.1 g ZIF-67 regular polyhedron was poured into 40 ml C2H5OH and ultrasonically dispersed. 20 ml C2H5OH solution in which 0.1 g TAA was dissolved was added dropwise into the above ZIF-67 dispersion solution and stirred for 10 min. The above mixed solution was transferred to a 100 ml polytetrafluoroethylene-lined autoclave, and finally placed in an oven, heated at 120 ° C for 4 h, washed several times with anhydrous ethanol, and finally dried in an oven at 60 ° C overnight to obtain black CoS with a particle size of 400-500 mm. x Hollow nanocages ( Figure 3 , 4).

[0043] (3) x mg (x = 5.6, 11.2 or 16.8) of CoS x The hollow nanocages were dissolved in 32 ml of deionized water and 8 ml of glycerol, and then 0.5 mmol of InCl3·4H2O and 0.75 mmol of TAA were added, ultrasonicated for 10 min, stirred for 15 min, and then transferred to a constant temperature oil bath furnace and heated to 90 ° C for 2 h. After cooling, deionized water and anhydrous ethanol were used to wash alternately, and dried at 60 ° C overnight to obtain hollow nanocages CoS with a particle size of 400-500 mm. x / In2S3 heterojunction sample( Figure 5 , 6).

[0044] After drying, the samples were collected and the samples prepared when x = 5.6, 11.2, and 16.8 were marked as CoS x / In2S3-1 (hereinafter referred to as CoIS-1), CoS x / In2S3-2 (hereinafter referred to as CoIS-2), CoS x / In2S3-3 (hereinafter referred to as CoIS-3). Figure 7 The XRD diffraction pattern shown in the figure shows that the prepared sample is CoS x / In2S3 heterojunction.

[0045] As a comparison of photocatalytic efficiency, the preparation method of pure In2S3 is consistent with the above experimental step (3), without adding CoS x powder.

[0046] Experiment 1

[0047] CoS prepared in Example 1 x / In2S3 heterojunction performance test:

[0048] The photocatalytic activity of all samples was evaluated by using a 300W xenon lamp with a 420nm filter to simulate visible light for the degradation of tetracycline hydrochloride (TCH). x / In2S3 heterojunction was ultrasonically dispersed in 100ml of TCH (50mg / L) aqueous solution. x The dispersed solution of the / In2S3 heterojunction was stirred for 1 h in the dark to reach adsorption-desorption equilibrium. Then, 3 ml of the solution was extracted every 10 min under irradiation of a PLS-SXE300 xenon lamp with a 420 nm filter and a power of 300 W, and then centrifuged and analyzed for the photocatalytic degradation of TCH using ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS).

[0049] Figure 8 and Fig. 9 For CoS x The degradation curve and degradation rate of the / In2S3 (CoIS) heterojunction as a photocatalytic material show that the degradation rate gradually increases with time, and the degradation rate of the composite CoIS is higher than that of the monomer CoS x Compared with In2S3, it can be shown that it has excellent photocatalytic degradation performance. x / In2S3 heterojunction can be used as a photocatalytic material for high-performance degradation of organic pollutants in water environments.

Claims

1. A Hollow Nanocage CoS x / In2S3 heterojunction preparation method, characterized in that, The following steps are involved: 1) In methanol solution, Co 2+ The source was combined with 2-methylimidazole at room temperature to obtain a regular polyhedron of ZIF-67; 2) The ZIF-67 regular polyhedron was sulfurized into CoS by a simple solvothermal method with thioacetamide at 120-180 °C. x Hollow nanocages; 3) In2S3 is loaded on CoS by a constant temperature oil bath method at 75-90°C. x On the surface, a layered hollow nanocage CoSx / In2S3 heterojunction coated with In2S3 nanosheets is formed.

2. The method according to claim 1, characterized in that The specific steps of obtaining the ZIF-67 regular polyhedron in step 1) are: adding Co 2+ The source and 2-methylimidazole are dissolved in CH3OH respectively to obtain dispersion A and dispersion B, dispersion A is quickly poured into dispersion B and then allowed to stand, the solid product is separated by centrifugation or filtration, washed several times with 2-methylimidazole, and dried to obtain ZIF-67 regular polyhedron; the Co 2+ The source is cobalt nitrate or cobalt nitrate hydrate.

3. The method according to claim 2, characterized in that The standing still is standing still for 24 hours.

4. The method according to claim 2, characterized in that: The Co 2+ The source is Co(NO3)2·5H2O.

5. The method according to claim 1, characterized in that Step 2) ZIF-67 regular polyhedron is sulfurized into CoS x The specific steps include: dispersing ZIF-67 regular polyhedrons in ethanol, then dropping an ethanol solution in which thioacetamide is dissolved, transferring to an autoclave and heating at 120-180°C for 3-4 hours, then washing and drying to obtain black CoS x Hollow nanocages; wherein the weight ratio of ZIF-67 regular polyhedrons to thioacetamide is between 0.5-2.

6. The method according to claim 1, characterized in that In step 3), In2S3 is loaded on CoS x The specific steps include: x The hollow nanocages were dissolved in a mixed solution of deionized water and glycerol, and In 3+ The source and thioacetamide are added, and then subjected to ultrasonication and / or stirring, and then placed in a constant temperature oil bath at 75-90°C for 1-3 hours, and then cooled, cleaned and dried to obtain CoS x / In2S3 heterojunction; control In 3+ In source and thioacetamide 3+ and S 2- The molar ratio is 1:3, In 3+ and CoS x The molar mass ratio of the hollow nanocages is 0.25 mol:(5.6-16.8) g.

7. The method according to claim 6, characterized in that In the mixed solution of deionized water and glycerol, the volume ratio of deionized water to glycerol is 4:

1.

8. The method according to claim 6, characterized in that In 3+ The source is indium chloride or indium chloride hydrate.

9. A hollow nanocage CoS prepared by the method according to any one of claims 1 to 8 x / In2S3 heterojunction.

10. The heterojunction according to claim 9 is used for photocatalytic degradation of organic pollutants in water environment.

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