Defect-rich bismuth oxychloride photocatalyst, preparation method and application

Abstract

The invention provides a defect-rich bismuth oxychloride photocatalyst and a preparation method and application thereof.The method comprises the steps that bismuth nitrate pentahydrate and potassium chloride are dissolved and stirred in ethyl alcohol to obtain a dissolved solution, a solvothermal product is taken out to be alternately washed with ethyl alcohol and deionized water and placed in a vacuum oven to be dried, and the defect-rich bismuth oxychloride photocatalyst is obtained; the preparation method comprises the following steps: preparing a bismuth oxychloride carrier with oxygen vacancies, dissolving polypropylene pyrrolidone and anhydrous copper acetate in absolute ethyl alcohol, dropwise adding ascorbic acid into a stirring solution, stirring to react, alternately washing the reaction solution by using deionized water and ethyl alcohol, and drying to obtain copper nanoparticles. The preparation method comprises the following steps: adding a bismuth oxychloride carrier into a copper nanoparticle dispersion solution, carrying out ultrasonic dispersion in deionized water, putting the bismuth oxychloride carrier into the copper nanoparticle dispersion solution, stirring, standing, and freeze-drying in a liquid nitrogen environment to obtain the bismuth oxychloride photocatalyst. A semiconductor carrier with oxygen vacancies is prepared by adopting a simple ethanol solvothermal strategy, and CO2 reduction is catalyzed under an illumination condition to realize excellent acetic acid selectivity.

Description

Technical Field

[0001] The present invention belongs to the fields of catalyst material technology and environmental protection, and particularly relates to a defect-rich bismuth oxychloride photocatalyst, a preparation method and an application thereof. Background Art

[0002] At present, there have been a lot of related studies on the photocatalytic reduction of CO2 to C1 products such as CO, CH4, methanol, etc. (Small2023, 19, 2207581); however, the high selectivity of CO2 to C2 + Products such as ethanol and acetic acid are still very challenging. This is because the C2 + The formation of products has the characteristics of high energy barrier, slow kinetics and low efficiency due to the complex multi-electron and CC coupling process involved in the process itself. + The products require rationally designed photocatalysts to overcome the above challenges.

[0003] Currently, in the field of electrocatalysis and photocatalysis, *CO and *COOH formed during the reaction process are key intermediates in the CC coupling process. Recent studies have shown that the construction of oxygen vacancy active sites on the surface of metal oxide semiconductors has a significant impact on CO2 photoreduction. For example, the construction of oxygen vacancies on the surface of WO3·0.33H2O is conducive to the adsorption and activation of CO2 to form *COOH, an important intermediate in the acetic acid process, and achieves excellent and stable acetic acid activity and selectivity under sunlight simulation conditions ( J. Am. Chem. Soc. 2018, 140 , 6474-6482). At the same time, because the Cu metal active site has a moderate adsorption strength for *CO in the reaction process, it is conducive to the formation of *CO intermediates and subsequent CC coupling in the entire reaction process, and is widely used in the photocatalytic CO2 to C2 + product( Angew. Chem. Int. Ed. 2022, 61 , e202208904); In addition, as a conductor, the introduction of Cu metal active sites can quickly separate photogenerated electron-hole pairs, increase the number of effective photogenerated carriers produced by the photocatalyst, and thus further improve the photoquantum efficiency of the entire catalytic process.

[0004] In order to achieve photocatalytic reduction of CO2 to C2 +The high catalytic performance of the product and how to form a local high concentration of *COOH and *CO intermediates on the catalyst surface to improve the selectivity of acetic acid in the product are one of the focuses of this study. The designed catalyst needs to have the following capabilities at the same time, mainly including high photogenerated carrier separation and utilization, efficient formation of *CO and *COOH intermediates, and low activation energy for CC coupling. The present invention constructs a photocatalyst carrier rich in oxygen vacancies, and enhances the adsorption and activation of CO2 and HCO3 by the catalyst through the asymmetric interface of oxygen vacancies. - At the same time, the Cu metal active center is further introduced to promote the formation of *CO intermediates, ultimately achieving highly selective photoreduction of CO2 to synthesize acetic acid. Summary of the Invention

[0005] In view of the above situation, the main purpose of the present invention is to propose a defect-rich bismuth oxychloride photocatalyst, a preparation method and application to solve the above technical problems.

[0006] The present invention provides a defect-rich bismuth oxychloride photocatalyst, wherein the catalyst is rich in oxygen vacancy bismuth oxychloride carrier, and the oxygen vacancy bismuth oxychloride carrier is BiOCl(Ov); The oxygen vacancy bismuth oxychloride support includes bismuth nitrate pentahydrate, potassium chloride and ethanol, and is prepared by an ethanol solvothermal method; The oxygen vacancy bismuth oxychloride support was dispersed in a Cu nanoparticle solution, stirred, and freeze-dried to obtain a defect-rich bismuth oxychloride photocatalyst. The Cu nanoparticle precursor is a metal nitrate, oxalate, halide or other complex salt.

[0007] The present invention provides a method for preparing a defect-rich bismuth oxychloride photocatalyst, which is used to prepare the above-mentioned defect-rich bismuth oxychloride photocatalyst. The method comprises the following steps: Step 1, dissolving bismuth nitrate pentahydrate and potassium chloride in ethanol and stirring to obtain a solution; Step 2, performing solvent heating on the dissolved solution in a polytetrafluoroethylene liner to obtain a solvent heating product; Step 3: taking out the product after the solvent heat and washing it alternately with ethanol and deionized water, and then washing it with deionized water to obtain a washed product, and placing the washed product in a vacuum oven to dry to obtain a bismuth oxychloride support with oxygen vacancies; Step 4: dissolving polypropylene pyrrolidone and anhydrous copper acetate in anhydrous ethanol and stirring the mixture in a warm water bath to obtain a stirred solution; adding ascorbic acid dropwise to the stirred solution and stirring the mixture to react to obtain a reaction solution; washing the reaction solution with deionized water and ethanol alternately, and drying the solution in a vacuum oven to obtain copper nanoparticles; Step 5, ultrasonically dispersing the copper nanoparticles in deionized water to obtain a copper nanoparticle dispersion solution; Step 6: Place the bismuth oxychloride carrier into the copper nanoparticle dispersion solution and stir the solution. After stirring, allow the solution to stand to obtain a solution after standing. Step 7: placing the solution after standing in a liquid nitrogen environment for freeze drying. After freeze drying is completed, a bismuth oxychloride photocatalyst is obtained.

[0008] The present invention also proposes an application of a defect-rich bismuth oxychloride photocatalyst, using the above-mentioned Ce-rich 3+ A method for preparing a defect-rich bismuth oxychloride photocatalyst prepared by a method for preparing a cubic phase lanthanum ferrite magneto-optical film is used for preparing acetic acid by photocatalytic reduction of carbon dioxide; the defect-rich bismuth oxychloride photocatalyst is used to prepare acetic acid under pure water conditions; The preparation method specifically comprises the following steps: Step 1: placing a bismuth oxychloride photocatalyst and a magnetic stirrer at the bottom of a quartz cup reactor; Step 2: Pour ultrapure water into a quartz cup and treat under ultrasonic conditions to obtain a fully dispersed solution; Step 3: Place the quartz cup in a photocatalytic reactor, introduce high-purity carbon dioxide once, and then perform a gas washing process; Step 4: After introducing secondary high-purity carbon dioxide, set the reaction temperature, stir, and turn on the xenon lamp; Step 5: After the reaction is completed, the reaction gas is introduced into GC for analysis of the gas phase product; the liquid after the reaction is centrifuged, and the supernatant is taken out for H-NMR detection to calculate the activity of the liquid phase product; Step 6: Calculate the selectivity of acetic acid in the liquid phase product using the formula. The selectivity calculation formula for acetic acid is as follows: .

[0009] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention adopts a simple ethanol solvothermal strategy to prepare a semiconductor carrier with oxygen vacancies; at the same time, Cu nanoparticles are synthesized by chemical reduction and Cu is successfully uniformly loaded on the carrier surface by chemical impregnation. Due to the synergistic effect of oxygen vacancies and Cu sites in the catalyst, the catalyst catalyzes CO2 reduction under light conditions and achieves excellent acetic acid selectivity.

[0010] 2. The metal Cu loading in the catalyst of the present invention is low and the cost of the metal precursor raw materials used in the catalyst is low, which is conducive to the further industrial promotion of the catalyst. In addition, the preparation process of the catalyst is simple and the raw materials are simple and easy to obtain, and it has the potential for industrial application.

[0011] 3. The photocatalytic reaction in the present invention uses pure water as an electron donor, which can effectively promote the photoreduction of water and improve environmental protection.

[0012] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is the SEM image of the prepared BiOCl support; Figure 2 is the HR-TEM image of the prepared BiOCl support; Figure 3 is the SEM image of the prepared BiOCl(Ov) support; Figure 4 is the HR-TEM image of the prepared BiOCl(Ov) support; Figure 5 is the HAADF-STEM image of the prepared BiOCl(Ov) support; Figure 6 is the HR-TEM image of the prepared Cu@BiOCl(Ov)-1.0 catalyst; Figure 7 is the EDS image of the prepared Cu@BiOCl(Ov)-1.0 catalyst; Figure 8 is the EPR diagram of the prepared catalyst; Figure 9 is the XPS-O1s pattern of the prepared catalyst; Figure 10 is the XRD comparison diagram of the prepared catalysts; Figure 11 It is a performance comparison chart of the prepared catalysts; Figure 12 This is a performance comparison chart of the prepared catalysts. DETAILED DESCRIPTION

[0014] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0015] These and other aspects of the embodiments of the present invention will become clear with reference to the following description and accompanying drawings. In these descriptions and accompanying drawings, some specific implementations of the embodiments of the present invention are specifically disclosed to illustrate some ways of implementing the principles of the embodiments of the present invention, but it should be understood that the scope of the embodiments of the present invention is not limited thereto.

[0016] Example 1 A defect-rich bismuth oxychloride photocatalyst, wherein the catalyst is rich in oxygen vacancy bismuth oxychloride carrier, and the oxygen vacancy bismuth oxychloride carrier is BiOCl(Ov); The oxygen vacancy bismuth oxychloride support includes bismuth nitrate pentahydrate, potassium chloride and ethanol, and is prepared by an ethanol solvothermal method; The oxygen vacancy bismuth oxychloride support was dispersed in a Cu nanoparticle solution, stirred, and freeze-dried to obtain a defect-rich bismuth oxychloride photocatalyst. The Cu nanoparticle precursor is a metal nitrate, oxalate, halide or other complex salt.

[0017] Example 2 This embodiment provides a method for preparing a defect-rich bismuth oxychloride photocatalyst, which is used to prepare the above-mentioned defect-rich bismuth oxychloride photocatalyst. The method comprises the following steps: Step 1: Dissolve 1 g of bismuth nitrate pentahydrate and 0.1 g of potassium chloride in 60 ml of ethanol and stir for 1 hour to obtain a solution; Step 2, subjecting the dissolved solution to solvent heating at 150° C. for 10 h in a 100 ml polytetrafluoroethylene liner to obtain a solvent heating product; Step 3: Take out the product after solvent heating and wash it alternately with ethanol and deionized water three times, and then wash it with deionized water three times to obtain a washed product. Place the washed product in a vacuum oven at 60°C to dry it to obtain a bismuth oxychloride support with oxygen vacancies, which is recorded as A1.

[0018] Example 3 This embodiment provides a method for preparing a defect-rich bismuth oxychloride photocatalyst, which is used to prepare the above-mentioned defect-rich bismuth oxychloride photocatalyst. The method comprises the following steps: Step 1: Dissolve 1.5 g of bismuth nitrate pentahydrate and 0.2 g of potassium chloride in a mixed solution of 40 mL of ethanol and 20 mL of deionized water for 2.5 hours with stirring to obtain a solution; Step 2, subjecting the dissolved solution to solvent heating at 165° C. for 12 h in a 100 ml polytetrafluoroethylene liner to obtain a solvent heating product; Step 3: Take out the solvent-heated product and wash it alternately with ethanol and deionized water three times, and then wash it with deionized water three times to obtain a washed product. Place the washed product in a vacuum oven at 60°C and dry it to obtain a bismuth oxychloride support with oxygen vacancies, which is recorded as A2.

[0019] Example 4 This embodiment provides a method for preparing a defect-rich bismuth oxychloride photocatalyst, which is used to prepare the above-mentioned defect-rich bismuth oxychloride photocatalyst. The method comprises the following steps: Step 1: Dissolve 3 g of bismuth nitrate pentahydrate and 0.5 g of potassium chloride in a mixed solution of 20 mL of ethanol and 40 mL of deionized water for 6 hours with stirring to obtain a solution; Step 2, subjecting the dissolved solution to solvent heating at 200° C. for 16 h in a 100 ml polytetrafluoroethylene liner to obtain a solvent heating product; Step 3: Take out the product after solvent heating and wash it alternately with ethanol and deionized water three times, and then wash it with deionized water three times to obtain a washed product. Place the washed product in a vacuum oven at 60°C and dry it to obtain a bismuth oxychloride support with oxygen vacancies, which is recorded as A3.

[0020] Example 5 This embodiment provides a method for preparing a defect-rich bismuth oxychloride photocatalyst, which is used to prepare the above-mentioned defect-rich bismuth oxychloride photocatalyst. The method comprises the following steps: Step 1, dissolving 0.5 g of polypropylene pyrrolidone and 200 mg of anhydrous copper acetate in 10 ml of anhydrous ethanol and stirring in a warm water bath to obtain a stirred liquid, adding 0.5 g of ascorbic acid dropwise to the stirred liquid and stirring for 30 minutes to react to obtain a reaction solution, and washing the reaction solution with deionized water and ethanol alternately. After washing, drying in a vacuum oven to obtain copper nanoparticles; Step 2: 5 mg of copper nanoparticles were dissolved in 10 ml of deionized water to obtain a copper nanoparticle dispersion solution, which was recorded as B1; Step 3: Take 200 ml of the bismuth oxychloride carrier in A1 and add it to 2.0 mg of the copper nanoparticle dispersion solution in B1, stirring the mixture. After stirring, let the mixture stand to obtain a solution after standing. Step 4: The solution after standing was placed in a liquid nitrogen environment for freeze drying. After freeze drying, a bismuth oxychloride photocatalyst loaded with 1.0 wt% Cu was obtained, which was recorded as Cu@BiOCl(Ov)-1.0.

[0021] Example 6 This embodiment provides a method for preparing a defect-rich bismuth oxychloride photocatalyst, which is used to prepare the above-mentioned defect-rich bismuth oxychloride photocatalyst. The method comprises the following steps: Step 1, dissolving 2 g of polypropylene pyrrolidone and 300 mg of anhydrous copper acetate in 25 ml of anhydrous ethanol and stirring in a warm water bath to obtain a stirred liquid, adding 1.5 g of ascorbic acid dropwise to the stirred liquid and stirring for 30 minutes to react to obtain a reaction solution, and washing the reaction solution with deionized water and ethanol alternately. After washing, the reaction solution is dried in a vacuum oven to obtain copper nanoparticles; Step 2: 10 mg of copper nanoparticles were dissolved in 10 ml of deionized water to obtain a copper nanoparticle dispersion solution, which was recorded as B2; Step 3: Take 200 ml of the bismuth oxychloride carrier in A1 and add it to 0.2 mg of the copper nanoparticle dispersion solution in B2, stirring the mixture. After stirring, let the mixture stand to obtain a solution after standing. Step 4: The solution after standing was placed in a liquid nitrogen environment for freeze drying. After freeze drying, a bismuth oxychloride photocatalyst loaded with 0.1 wt% Cu was obtained, which was recorded as Cu@BiOCl(Ov)-0.1.

[0022] Example 7 This embodiment provides a method for preparing a defect-rich bismuth oxychloride photocatalyst, which is used to prepare the above-mentioned defect-rich bismuth oxychloride photocatalyst. The method comprises the following steps: Step 1, dissolving 3.5 g of polypropylene pyrrolidone and 400 mg of anhydrous copper acetate in 35 ml of anhydrous ethanol and stirring in a warm water bath to obtain a stirred liquid, adding 2.5 g of ascorbic acid dropwise to the stirred liquid and stirring for 30 minutes to react to obtain a reaction solution, and washing the reaction solution with deionized water and ethanol alternately. After washing, the reaction solution is dried in a vacuum oven to obtain copper nanoparticles; Step 2: 15 mg of copper nanoparticles were dissolved in 10 ml of deionized water to obtain a copper nanoparticle dispersion solution, which was recorded as B3; Step 3: Take 200 ml of the bismuth oxychloride carrier in A1 and add it to 1.0 mg of the copper nanoparticle dispersion solution in B3, stirring the mixture. After stirring, let the mixture stand to obtain a solution after standing. Step 4: The solution after standing was placed in a liquid nitrogen environment for freeze drying. After freeze drying, a bismuth oxychloride photocatalyst loaded with 0.5 wt% Cu was obtained, which was recorded as Cu@BiOCl(Ov)-0.5.

[0023] Example 8 This embodiment provides a method for preparing a defect-rich bismuth oxychloride photocatalyst, which is used to prepare the above-mentioned defect-rich bismuth oxychloride photocatalyst. The method comprises the following steps: Step 1, dissolving 5 g of polypropylene pyrrolidone and 500 mg of anhydrous copper acetate in 50 ml of anhydrous ethanol and stirring in a warm water bath to obtain a stirred liquid, adding 3 g of ascorbic acid dropwise to the stirred liquid and stirring for 30 minutes to react to obtain a reaction solution, and washing the reaction solution with deionized water and ethanol alternately. After washing, the reaction solution is dried in a vacuum oven to obtain copper nanoparticles; Step 2: 20 mg of copper nanoparticles were dissolved in 10 ml of deionized water to obtain a copper nanoparticle dispersion solution, which was recorded as B4; Step 3: Take 200 ml of the bismuth oxychloride carrier in A1 and add it to 4.0 mg of the copper nanoparticle dispersion solution in B4, stirring the mixture. After stirring, let the mixture stand to obtain a solution after standing. Step 4: The solution after standing was placed in a liquid nitrogen environment for freeze drying. After freeze drying, a bismuth oxychloride photocatalyst loaded with 2.0 wt% Cu was obtained, which was recorded as Cu@BiOCl(Ov)-2.0.

[0024] Comparative Example 1 This comparative example provides a method for preparing a BiOCl material having oxygen vacancies, which is different from that in Example 2, and is used to prepare a photocatalyst having oxygen vacancies. The method comprises the following steps: Step 1: dissolve 2.425 g of bismuth nitrate pentahydrate and 0.373 g of potassium chloride in 60 ml of ethanol, and stir the mixture with a magnetic stirrer at 500 rpm / min for 2 h to obtain a magnetic stirring solution. Step 2, transfer the magnetically stirred solution to a 100 mL polytetrafluoroethylene liner and perform solvothermal treatment at 160°C for 16 h to obtain a solvothermal product; Step 3: Take out the product after solvent heating and perform three centrifugal washings, ethanol, and deionized water alternating washings. After the alternating washings are completed, wash it twice continuously with deionized water. After the washings are completed, bake the product in a vacuum oven at 60°C for 24 hours to obtain a photocatalyst with oxygen vacancies, which is recorded as BiOCl(Ov).

[0025] Comparative Example 2 The difference between this comparative example and comparative example 1 is that 2.425 g of bismuth nitrate pentahydrate and 0.373 g of potassium chloride are dissolved in a mixed solution of 40 ml of ethanol and 20 ml of deionized water, and the mixture is magnetically stirred for 2 h using a 500 rpm / min magnetic stirrer to obtain a magnetically stirred solution, and the magnetically stirred solution is transferred to a 100 mL polytetrafluoroethylene liner and solvent-heated at 160 ° C for 16 h to obtain a solvent-heated product, which is a photocatalyst with oxygen vacancies, recorded as BiOCl (Ov-1).

[0026] The ratio of ethanol to deionized water is 2:1.

[0027] Comparative Example 3 The difference between this comparative example and comparative example 1 is that 2.425 g of bismuth nitrate pentahydrate and 0.373 g of potassium chloride are dissolved in a mixed solution of 20 ml of ethanol and 40 ml of deionized water, and the mixture is magnetically stirred for 2 h using a 500 rpm / min magnetic stirrer to obtain a magnetic stirring solution, and the magnetic stirring solution is transferred to a 100 mL polytetrafluoroethylene liner and solvent heated at 160 ° C for 16 h to obtain a solvent thermal product, which is a photocatalyst with oxygen vacancies, recorded as BiOCl (Ov-2).

[0028] The ratio of ethanol to deionized water is 1:2.

[0029] Comparative Example 4 The difference between this comparative example and comparative example 1 is that 2.425 g of bismuth nitrate pentahydrate and 0.373 g of potassium chloride are dissolved in 60 ml of a mixed solution of deionized water, and the mixture is magnetically stirred for 2 h using a 500 rpm / min magnetic stirrer to obtain a magnetically stirred solution. The magnetically stirred solution is transferred to a 100 mL polytetrafluoroethylene liner and subjected to solvothermal treatment at 160° C. for 16 h to obtain a solvothermal product, which is a photocatalyst with oxygen vacancies and is recorded as BiOCl.

[0030] Application Example 1 This embodiment provides an application of a defect-rich bismuth oxychloride photocatalyst, wherein the bismuth oxychloride photocatalysts prepared in Examples 2 to 8 and Comparative Examples 1 to 4 are used in the preparation of acetic acid by photocatalytic reduction of carbon dioxide. The defect-rich bismuth oxychloride photocatalyst is used to prepare acetic acid in pure water; The preparation method specifically comprises the following steps: Step 1, 20 mg of photocatalyst and a magnetic stirrer were weighed from Cu@BiOCl(Ov)-1.0, Cu@BiOCl(Ov)-0.1, Cu@BiOCl(Ov)-0.5, Cu@BiOCl(Ov)-2.0, BiOCl(Ov), BiOCl(Ov-1), BiOCl(Ov-2) and BiOCl, respectively, and placed at the bottom of a quartz cup reactor with an inner diameter of 50 mm; Step 2: Pour 5.0 ml of ultrapure water into a quartz cup and treat under ultrasonic conditions for 1 minute to obtain a fully dispersed solution; Step 3: Place the quartz cup in a photocatalytic reactor, introduce high-purity carbon dioxide to 2.0 MPa, and repeat the gas washing process three times; Step 4: After the scrubbing treatment is completed, the pressure is set to 4.0 MPa, the reaction temperature is 50°C, and stirring is performed, and a 300W xenon lamp is turned on; Among them, the xenon lamp is PLS-SXE300 + / UV xenon lamp light source; Step 5: After the reaction is completed, the reaction gas is introduced into GC for analysis of the gas phase product; the liquid after the reaction is centrifuged, and the supernatant is taken out for H-NMR detection to calculate the activity of the liquid phase product; Step 6: Calculate the selectivity of acetic acid in the liquid phase product using the formula. The selectivity calculation formula for acetic acid is as follows: .

[0031] In order to verify the effectiveness of the present invention, Figure 1 This is the SEM image of the prepared BiOCl catalyst. It can be seen from the figure that the synthesized BiOCl presents a regular flake structure compared with BiOCl(Ov).

[0032] Figure 2 The HR-TEM image of the prepared Cu@BiOCl(Ov)-1.0 catalyst is shown in Figure 2. Combined with the above electron microscopy images, it can be seen that Cu nanoparticles are uniformly distributed on the BiOCl(Ov) support and are approximately 5 nm in size.

[0033] Figure 3 This is the SEM image of the prepared BiOCl(Ov). From the image, we can see that the synthesized BiOCl(Ov) has a flake structure and aggregation phenomenon.

[0034] See also Figure 4 , Figure 4 This is the HR-TEM image of the BiOCl(Ov) catalyst. Under HR-TEM, it can be observed that there are discontinuous areas of crystal stripes on the surface of the bismuth oxychloride photocatalyst, which verifies that its surface has rich defects.

[0035] See also Figure 5 , Figure 5 The HAADF-STEM image of the BiOCl catalyst is further used to directly visualize the oxygen vacancies on the surface of the BiOCl(Ov) sample using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Figure 5 As shown in the figure, the (110) and (200) crystal planes intersecting at an angle of 45° on the sample surface can be marked as the [0 0 1] region of the tetragonal lattice structure BiOCl. At the same time, there is an obvious surface atom loss phenomenon in the marked area. In this area, the Bi and O atoms of the sample are arranged as follows Figure 5As shown in the right figure, considering that the atomic number of Bi is significantly higher than that of Cl and O, the brightness of Bi atoms in the image will be much higher than that of O atoms. It can be inferred that the missing atoms are O atoms. At the same time, the corresponding line profile analysis is performed in the marked area. The valley bottom with periodic Bi-O distribution can be clearly identified as surface oxygen vacancies. In the model in the lower right corner, the yellow balls represent Bi atoms and the red balls represent O atoms ( Figure 5 ). Figure 6 This is a high-resolution transmission electron microscopy image of Cu-loaded BiOCl. From the image, we can see that Cu exists on the surface of the catalyst in the form of nanoparticles, while BiOCl still maintains a flake structure.

[0036] Figure 7 This is the elemental distribution diagram of the Cu-loaded BiOCl sample, where red represents Bi, purple represents Cl, blue represents O, and green represents Cu. The diagram shows that Cu is uniformly loaded on the catalyst surface.

[0037] exist Figure 8 The EPR technique was used to demonstrate that compared with BiOCl synthesized under hydrothermal conditions, the BiOCl(Ov) prepared by the ethanol solvothermal strategy has richer surface oxygen vacancies. Figure 9 XPS-O1s analysis was performed on BiOCl synthesized by different methods, and the results also showed that the surface oxygen vacancy content of BiOCl(Ov) was significantly higher than that of BiOCl.

[0038] See also Figure 10 , Figure 10 The XRD comparison diagrams of the catalysts prepared in Example 1, Comparative Example 1 and Comparative Example 4 show that no obvious characteristic diffraction peak related to Cu appears in the Cu@BiOCl(Ov)-1.0 catalyst, indicating that the Cu NPs on the catalyst surface may be highly dispersed.

[0039] The test results of photocatalytic carbon dioxide reduction are as follows Figure 11 and Figure 12 It shows that under light conditions, as the proportion of ethanol in the solution continues to increase during the solvothermal process, the activity of the synthesized catalyst towards acetic acid also continues to increase.

[0040] Cu NPs were further introduced on the BiOCl(Ov) surface. The photocatalytic CO2 test results showed that with the continuous increase of Cu loading, the acetic acid activity in the product showed a trend of first increasing and then decreasing. When the loading was 1.0 wt%, the acetic acid activity was the highest, reaching 161.2 μmol / g. cat / h, corresponding to an acetic acid selectivity of 97.3%.

[0041] The photocatalytic activity test results of the catalysts in the examples and comparative examples are shown in Table 1.

[0042] Table 1:

[0043] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0044] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a defect-rich bismuth oxychloride photocatalyst, characterized in that: The method comprises the following steps: Step 1, dissolving bismuth nitrate pentahydrate and potassium chloride in a solvent and stirring to obtain a solution; Step 2, performing solvent heating on the dissolved solution in a polytetrafluoroethylene liner to obtain a solvent heating product; Step 3: taking out the product after the solvent heat and washing it alternately with ethanol and deionized water, and then washing it with deionized water to obtain a washed product, and placing the washed product in a vacuum oven to dry to obtain a bismuth oxychloride support with oxygen vacancies; Step 4: dissolving polypropylene pyrrolidone and anhydrous copper acetate in anhydrous ethanol and stirring the mixture in a warm water bath to obtain a stirred solution; adding ascorbic acid dropwise to the stirred solution for stirring and reacting to obtain a reaction solution; and washing the reaction solution alternately with deionized water and ethanol. After washing, the reaction solution is dried in a vacuum oven to obtain copper nanoparticles; Step 5: adding copper nanoparticles to deionized water to obtain a copper nanoparticle dispersion solution; Step 6: Place the bismuth oxychloride carrier into the copper nanoparticle dispersion solution and stir the solution. After stirring, allow the solution to stand to obtain a solution after standing. Step 7: placing the solution after standing in a liquid nitrogen environment for freeze drying. After freeze drying is completed, a bismuth oxychloride photocatalyst is obtained.

2. The method for preparing a defect-rich bismuth oxychloride photocatalyst according to claim 1, wherein: The dissolving agent is ethanol, a mixture of ethanol and deionized water, or a deionized water mixed solution.

3. The method for preparing a defect-rich bismuth oxychloride photocatalyst according to claim 2, wherein: In the process of obtaining a bismuth oxychloride carrier with oxygen vacancies, the mass of bismuth nitrate pentahydrate is 1-3 g, the mass of potassium chloride is 0.1-0.5 g, the volume ratio of ethanol to deionized water in a mixture of ethanol and deionized water is 1:2 or 2:1, the volume of the deionized water mixed solution is 60 ml, the dissolution stirring time is 1-6 hours, the volume of polytetrafluoroethylene is 100 ml, the solvent thermal temperature is 150-200° C., the solvent thermal time is 10-16 hours, the number of alternating washings with ethanol and deionized water is 3 times, the number of washings with deionized water is 3 times, and the vacuum oven temperature is 60° C.

4. The method for preparing a defect-rich bismuth oxychloride photocatalyst according to claim 3, wherein: In the process of obtaining the solution after standing, the mass of polypropylene pyrrolidone is 0.5~5g, the volume of anhydrous copper acetate is 200~500ml, the volume of anhydrous ethanol is 10~50ml, the mass of ascorbic acid is 0.5~3g, the dropwise addition and stirring time is 30min, the vacuum oven temperature is 60°C, the mass of copper nanoparticles is 5~20mg, the volume of deionized water ultrasonic dispersion is 10ml, the volume of copper nanoparticle dispersion solution is 0.2~4.0mg, and the standing time is 24h.

5. The method for preparing a defect-rich bismuth oxychloride photocatalyst according to claim 4, characterized in that: In the process of obtaining the bismuth oxychloride photocatalyst, the loading amount of the bismuth oxychloride photocatalyst is 0.1-2.0 wt%, and Cu is dispersed and evenly distributed in the bismuth oxychloride photocatalyst.

6. A defect-rich bismuth oxychloride photocatalyst, characterized in that The defect-rich bismuth oxychloride photocatalyst is prepared by the preparation method according to any one of claims 1 to 5, wherein the catalyst is rich in oxygen vacancy bismuth oxychloride carrier, and the oxygen vacancy bismuth oxychloride carrier is BiOCl(Ov); The oxygen vacancy bismuth oxychloride support includes bismuth nitrate pentahydrate, potassium chloride and ethanol, and is prepared by an ethanol solvothermal method; The oxygen vacancy bismuth oxychloride support was dispersed in a Cu nanoparticle solution, stirred, and freeze-dried to obtain a defect-rich bismuth oxychloride photocatalyst. The Cu nanoparticle precursor is a metal nitrate, oxalate, halide or other complex salt.

7. An application of a defect-rich bismuth oxychloride photocatalyst, using the defect-rich bismuth oxychloride photocatalyst according to claim 6, characterized in that: The defect-rich bismuth oxychloride photocatalyst is used for preparing acetic acid by photocatalytic reduction of carbon dioxide.

8. The use of a defect-rich bismuth oxychloride photocatalyst according to claim 7, characterized in that: The defect-rich bismuth oxychloride photocatalyst is used to prepare acetic acid in pure water; The preparation method specifically comprises the following steps: S1, placing bismuth oxychloride photocatalyst and magnetic stirrer at the bottom of quartz cup reactor; S2. Pour ultrapure water into a quartz cup and place the quartz cup under ultrasonic conditions to obtain a fully dispersed solution; S3, placing the quartz cup in a photocatalytic reactor, introducing high-purity carbon dioxide and repeating the gas washing process; S4. After the scrubbing process is completed, the pressure and reaction temperature are set and stirring is performed, and the xenon lamp is turned on; S5. After the reaction is completed, the reaction gas is introduced into GC for analysis of the gas phase product; the liquid after the reaction is centrifuged, and the supernatant is taken out for H-NMR detection to calculate the activity of the liquid phase product; S6. Calculate the selectivity of acetic acid in the liquid phase product using the formula. The selectivity calculation formula for acetic acid is as follows: 。 9. The use of a defect-rich bismuth oxychloride photocatalyst according to claim 8, characterized in that: In the process of calculating the selectivity of acetic acid in the product, the mass of bismuth oxychloride photocatalyst weighed was 20 mg, the inner diameter of the quartz cup was 50 mm, the volume of ultrapure water was 5.0 ml, the purity of high-purity carbon dioxide was 99.999%, the pressure after the secondary high-purity carbon dioxide was introduced was 2.0 MPa, the gas washing treatment was repeated 3 times, the reaction temperature was 50°C, the reaction pressure was 4.0 MPa, and the reaction light source was a 300W xenon lamp.

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