Defect-rich bismuth oxychloride photocatalyst, preparation method and application thereof

Abstract

The application provides a kind of rich defect bismuth oxychloride photocatalyst, preparation method and application, the method is by dissolving and stirring bismuth nitrate pentahydrate and potassium chloride in ethanol, obtain the dissolution solution, take out the product after solvent heating and carry out the alternate washing of ethanol and deionized water and place in vacuum oven drying, obtain the bismuth oxychloride carrier with oxygen vacancy, take polypropylene pyrrolidone and anhydrous copper acetate in anhydrous ethanol are dissolved, ascorbic acid is added dropwise in stirring liquid and stirred to react, the reaction solution is washed with deionized water and ethanol alternately and dried, copper nanoparticles are obtained, and ultrasonic dispersion is carried out in deionized water, take bismuth oxychloride carrier and put into copper nanoparticle dispersion solution, stir and stand, and freeze-drying under liquid nitrogen environment, to obtain bismuth oxychloride photocatalyst. The application is prepared by using simple ethanol solvent heating strategy to prepare semiconductor carrier with oxygen vacancy, and excellent acetic acid selectivity is realized under light condition to catalyze CO2 reduction.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalyst materials and environmental protection, and particularly relates to a defect-rich bismuth oxychloride photocatalyst, a preparation method and application thereof. BACKGROUND

[0002] At present, there are a large number of related researches on photocatalytic reduction of CO2 into C1 products such as CO, CH4, methanol and the like (Small 2023, 19, 2207581); but it is still a great challenge to convert CO2 into C2 + products such as ethanol and acetic acid with high selectivity. This is because the formation of C2 + products in the photocatalytic process has the characteristics of high energy barrier, slow kinetics and low efficiency due to the complex multi-electron and C-C coupling process involved in the process itself. In order to photocatalytically convert CO2 into C2 + products, a reasonable photocatalyst needs to be designed to overcome the above challenges.

[0003] At present, in the fields of electrocatalysis and photocatalysis, *CO and *COOH formed in the reaction process are key intermediates in the C-C coupling process. It has been recently shown that the construction of oxygen vacancy active sites on the surface of metal oxide semiconductors has a significant influence on the photocatalytic reduction of CO2. For example, the construction of oxygen vacancies on the surface of WO3·0.33H2O is beneficial to the formation of *COOH, which is an important intermediate in the process of CO2 adsorption and activation to form acetic acid, and realizes excellent and stable acetic acid activity and selectivity under simulated sunlight conditions (Small 2018, J. Am. Chem. Soc. 2018, 140 , 6474-6482). At the same time, Cu metal active sites are widely used in photocatalytic preparation of C2 + products from CO2 because the Cu metal active sites have moderate adsorption strength on the *CO intermediate in the reaction process, thereby facilitating the formation of the *CO intermediate and subsequent C-C coupling (Small 2022, Angew. Chem. Int. Ed. 2022, 61 , e202208904); in addition, as a conductor, the introduction of Cu metal active sites can quickly separate photo-generated electron-hole pairs, increase the number of effective photo-generated carriers produced by the photocatalyst, and further improve the photo quantum efficiency of the entire catalytic process.

[0004] In order to realize photocatalytic reduction of CO2 into C2 +The high catalytic performance of the product, and how to form a local high concentration of COOH and CO intermediates on the surface of the catalyst to improve the selectivity of acetic acid in the product are one of the focuses of the present research. The designed catalyst needs to have the following abilities at the same time, mainly including high light carrier separation ability and utilization, efficient formation of CO, COOH intermediates and low activation energy of C-C coupling. The present application constructs an oxygen vacancy-rich photocatalyst carrier, enhances the adsorption and activation of CO2 on the catalyst through the asymmetric interface of the oxygen vacancy, and promotes the formation of the HCO3 - intermediate, and promotes the formation of the *COOH intermediate, while further introducing a Cu metal active center to promote the formation of the *CO intermediate, finally realizing high selectivity of the photocatalytic reduction of CO2 to synthesize acetic acid. SUMMARY

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

[0006] The present application proposes a defect-rich bismuth oxychloride photocatalyst, which is rich in oxygen vacancy bismuth oxychloride carriers, and the oxygen vacancy bismuth oxychloride carrier is BiOCl(Ov);

[0007] The oxygen vacancy bismuth oxychloride carrier includes bismuth nitrate pentahydrate, potassium chloride and ethanol, and is prepared by an ethanol solvothermal method;

[0008] The oxygen vacancy bismuth oxychloride carrier is dispersed in a Cu nanoparticle solution for stirring, and freeze-drying is performed to obtain the defect-rich bismuth oxychloride photocatalyst;

[0009] The Cu nanoparticle precursor is a metal nitrate, oxalate, halide or other complex salt.

[0010] The present application proposes a preparation method of a defect-rich bismuth oxychloride photocatalyst, which is used for preparing the above-mentioned defect-rich bismuth oxychloride photocatalyst, and the method comprises the following steps:

[0011] Step 1, dissolve and stir bismuth nitrate pentahydrate and potassium chloride in ethanol to obtain a dissolution solution;

[0012] Step 2, perform solvothermal treatment on the dissolution solution in a polytetrafluoroethylene liner to obtain a product after solvothermal treatment;

[0013] Step 3, take out the product after solvothermal treatment, and perform alternating washing with ethanol and deionized water, and then wash with deionized water again to obtain a washed product, and place the washed product in a vacuum oven for drying to obtain a bismuth oxychloride carrier with oxygen vacancies;

[0014] Step 4, polypropylene pyrrolidone and anhydrous copper acetate are dissolved in anhydrous ethanol, and stirring is carried out under the condition of a warm water bath to obtain a stirring solution; ascorbic acid is added dropwise into the stirring solution for stirring and reaction, a reaction solution is obtained, and the reaction solution is washed with deionized water and ethanol alternately, and then dried in a vacuum oven to obtain copper nanoparticles;

[0015] Step 5, the copper nanoparticles are ultrasonically dispersed in deionized water to obtain a copper nanoparticle dispersion solution;

[0016] Step 6, the bismuth oxychloride carrier is placed into the copper nanoparticle dispersion solution for stirring, and then left to stand to obtain a standing solution;

[0017] Step 7, the standing solution is subjected to freeze-drying under a liquid nitrogen environment, and then a bismuth oxychloride photocatalyst is obtained.

[0018] The application further provides an application of the defect-rich bismuth oxychloride photocatalyst. 3+ The defect-rich bismuth oxychloride photocatalyst prepared by the preparation method is used for preparing acetic acid by photocatalytic reduction of carbon dioxide; and the defect-rich bismuth oxychloride photocatalyst is used for preparing acetic acid under pure water conditions.

[0019] The preparation method specifically comprises the following steps:

[0020] Step 1, the bismuth oxychloride photocatalyst and a magnetic stirring bar are placed at the bottom of a quartz cup reactor;

[0021] Step 2, ultrapure water is poured into the quartz cup, and the quartz cup is subjected to ultrasonic treatment to obtain a fully dispersed solution;

[0022] Step 3, the quartz cup is placed in a photocatalytic reaction kettle, and once high-purity carbon dioxide is introduced for gas washing treatment;

[0023] Step 4, after twice high-purity carbon dioxide is introduced, stirring is carried out after setting the reaction temperature, and a xenon lamp is turned on;

[0024] Step 5, after the reaction is completed, the reaction gas is introduced into a GC for analysis of gas-phase products; the liquid after the reaction is subjected to centrifugal separation, and the supernatant is taken out for H-NMR detection to calculate the activity of liquid-phase products;

[0025] Step 6, the selectivity of acetic acid in the liquid-phase products is calculated by a formula, and the formula for calculating the selectivity of acetic acid is as follows:

[0026] .

[0027] Compared with the prior art, the application has the following beneficial effects:

[0028] 1、The application is prepared by adopting simple ethanol solvent hot strategy semiconductor carrier with oxygen vacancy; simultaneously through chemical reduction method synthesis Cu nanoparticles and via chemical immersion method successfully realizes carrier surface uniform load Cu, due to the synergistic effect of oxygen vacancy and Cu site in the catalyst, makes the catalyst under light condition catalytic CO2 reduction realizes excellent acetic acid selectivity.

[0029] 2、The catalyst in the application has low metal Cu loading, and the metal precursor raw material cost of the catalyst is low, which is beneficial to further industrialization of the catalyst, and the catalyst preparation process is simple, the raw material is simple and easy to obtain, and has industrial application potential.

[0030] 3、The photocatalytic reaction in the application adopts pure water as an electron donor, which can effectively promote the photoreduction of water and improve environmental protection.

[0031] Additional aspects and advantages of the application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is the SEM diagram of the prepared BiOCl carrier;

[0033] Figure 2 is the HR-TEM diagram of the prepared BiOCl carrier;

[0034] Figure 3 is the SEM diagram of the prepared BiOCl(Ov) carrier;

[0035] Figure 4 is the HR-TEM diagram of the prepared BiOCl(Ov) carrier;

[0036] Figure 5 is the HAADF-STEM diagram of the prepared BiOCl(Ov) carrier;

[0037] Figure 6 is the HR-TEM diagram of the prepared Cu@BiOCl(Ov)-1.0 catalyst;

[0038] Figure 7 is the EDS diagram of the prepared Cu@BiOCl(Ov)-1.0 catalyst;

[0039] Figure 8 is the EPR diagram of the prepared catalyst;

[0040] Figure 9 is the XPS-O1s diagram of the prepared catalyst;

[0041] Figure 10is a comparison chart of XRD of the prepared catalysts;

[0042] Figure 11 is a comparison chart of performance of the prepared catalysts;

[0043] Figure 12 is a comparison chart of performance of the prepared catalysts. DETAILED DESCRIPTION

[0044] Embodiments of the present application are described below in detail with reference to the accompanying drawings, wherein the same or similar components are denoted by the same or similar reference numerals throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are for the purpose of explaining the present application, and should not be construed as limiting the present application.

[0045] These and other aspects of embodiments of the present application will be more apparent from the following description and accompanying drawings. In these descriptions and drawings, some specific embodiments of embodiments of the present application are specifically disclosed to represent some ways of embodying principles of embodiments of the present application, but it should be understood that the scope of embodiments of the present application is not limited thereto.

[0046] Embodiment 1

[0047] A defect-rich bismuth oxychloride photocatalyst, the catalyst being rich in an oxygen vacancy bismuth oxychloride carrier, the oxygen vacancy bismuth oxychloride carrier being BiOCl(Ov);

[0048] The oxygen vacancy bismuth oxychloride carrier comprises bismuth nitrate pentahydrate, potassium chloride and ethanol, and is prepared by an ethanol solvothermal method;

[0049] The oxygen vacancy bismuth oxychloride carrier is dispersed in a Cu nanoparticle solution for stirring, and freeze-drying is performed to obtain the defect-rich bismuth oxychloride photocatalyst;

[0050] The Cu nanoparticle precursor is a metal nitrate, oxalate, halide or other complex salt.

[0051] Embodiment 2

[0052] The embodiment provides a preparation method of a defect-rich bismuth oxychloride photocatalyst, which is used for preparing the above-mentioned defect-rich bismuth oxychloride photocatalyst, and the method comprises the following steps:

[0053] Step 1, 1g of bismuth nitrate pentahydrate and 0.1g of potassium chloride are dissolved and stirred in 60ml of ethanol for 1h to obtain a dissolved solution;

[0054] Step 2, the dissolved solution is subjected to 10h of solvothermal treatment at 150℃ in a 100ml polytetrafluoroethylene liner to obtain a solvothermally treated product;

[0055] Step 3, the product after solvent thermal is taken out and washed with ethanol and deionized water for three times alternately, and then washed with deionized water for three times to obtain a washed product, and the washed product is placed in a vacuum oven at 60°C for drying to obtain a bismuth oxychloride carrier with oxygen vacancies, denoted as A1.

[0056] Example 3

[0057] The embodiment provides a preparation method of a defect-rich bismuth oxychloride photocatalyst, and is used for preparing the defect-rich bismuth oxychloride photocatalyst.

[0058] Step 1, 1.5g of bismuth nitrate pentahydrate and 0.2g of potassium chloride are dissolved and stirred in a mixed solution of 40 mL of ethanol and 20 mL of deionized water for 2.5h to obtain a dissolved solution;

[0059] Step 2, the dissolved solution is subjected to solvent thermal at 165°C for 12h in a 100ml polytetrafluoroethylene liner to obtain a product after solvent thermal;

[0060] Step 3, the product after solvent thermal is taken out and washed with ethanol and deionized water for three times alternately, and then washed with deionized water for three times to obtain a washed product, and the washed product is placed in a vacuum oven at 60°C for drying to obtain a bismuth oxychloride carrier with oxygen vacancies, denoted as A1.

[0061] Example 4

[0062] The embodiment provides a preparation method of a defect-rich bismuth oxychloride photocatalyst, and is used for preparing the defect-rich bismuth oxychloride photocatalyst.

[0063] Step 1, 3g of bismuth nitrate pentahydrate and 0.5g of potassium chloride are dissolved and stirred in a mixed solution of 20 mL of ethanol and 40 mL of deionized water for 6h to obtain a dissolved solution;

[0064] Step 2, the dissolved solution is subjected to solvent thermal at 200°C for 16h in a 100ml polytetrafluoroethylene liner to obtain a product after solvent thermal;

[0065] Step 3, the product after solvent thermal is taken out and washed with ethanol and deionized water for three times alternately, and then washed with deionized water for three times to obtain a washed product, and the washed product is placed in a vacuum oven at 60°C for drying to obtain a bismuth oxychloride carrier with oxygen vacancies, denoted as A1.

[0066] Example 5

[0067] The embodiment provides a preparation method of a defect-rich bismuth oxychloride photocatalyst, and is used for preparing the defect-rich bismuth oxychloride photocatalyst.

[0068] Step 1, take 0.5g polypropylene pyrrolidone and 200mg anhydrous copper acetate in 10ml anhydrous ethanol for dissolution, and stirring under the condition of warm water bath, to obtain the stirring solution, 0.5g ascorbic acid is added dropwise in the stirring solution and stirred for 30min to react, to obtain the reaction solution, the reaction solution is washed with deionized water and ethanol alternately, and dried in a vacuum oven after washing to obtain copper nanoparticles;

[0069] Step 2, take 5mg copper nanoparticles in 10ml deionized water to obtain copper nanoparticle dispersion solution, marked as B1;

[0070] Step 3, take 200ml bismuth oxychloride carrier in A1 into 2.0mg copper nanoparticle dispersion solution in B1 for stirring, and after stirring, stand to obtain the standing solution;

[0071] Step 4, freeze-drying the standing solution in liquid nitrogen environment, and after freeze-drying, obtain bismuth oxychloride photocatalyst loaded with 1.0wt% Cu, marked as Cu@BiOCl(Ov)-1.0.

[0072] Example 6

[0073] The embodiment provides a preparation method of a defect-rich bismuth oxychloride photocatalyst, for preparing the above-mentioned defect-rich bismuth oxychloride photocatalyst, the method comprises the following steps:

[0074] Step 1, take 2g polypropylene pyrrolidone and 300mg anhydrous copper acetate in 25ml anhydrous ethanol for dissolution, and stirring under the condition of warm water bath, to obtain the stirring solution, 1.5g ascorbic acid is added dropwise in the stirring solution and stirred for 30min to react, to obtain the reaction solution, the reaction solution is washed with deionized water and ethanol alternately, and dried in a vacuum oven after washing to obtain copper nanoparticles;

[0075] Step 2, take 10mg copper nanoparticles in 10ml deionized water to obtain copper nanoparticle dispersion solution, marked as B2;

[0076] Step 3, take 200ml bismuth oxychloride carrier in A1 into 0.2mg copper nanoparticle dispersion solution in B2 for stirring, and after stirring, stand to obtain the standing solution;

[0077] Step 4, freeze-drying the standing solution in liquid nitrogen environment, and after freeze-drying, obtain bismuth oxychloride photocatalyst loaded with 0.1wt% Cu, marked as Cu@BiOCl(Ov)-0.1.

[0078] Example 7

[0079] The embodiment provides a preparation method of a defect-rich bismuth oxychloride photocatalyst.

[0080] Step 1, 3.5g polypropylene pyrrolidone and 400mg anhydrous copper acetate are dissolved in 35ml anhydrous ethanol, and stirring is carried out under the condition of a warm water bath to obtain a stirring solution, 2.5g ascorbic acid is added dropwise in the stirring solution and stirred for 30min to carry out reaction, a reaction solution is obtained, and the reaction solution is washed with deionized water and ethanol alternately, and then dried in a vacuum oven to obtain copper nanoparticles;

[0081] Step 2, 15mg copper nanoparticles are taken in 10ml deionized water to obtain a copper nanoparticle dispersion solution, denoted as B3;

[0082] Step 3, 200ml bismuth oxychloride carriers in A1 are put into 1.0mg copper nanoparticle dispersion solution in B3 to carry out stirring, and after stirring is completed, standing is carried out to obtain a standing solution;

[0083] Step 4, the standing solution is placed in a liquid nitrogen environment to carry out freeze-drying, and after freeze-drying is completed, a bismuth oxychloride photocatalyst loaded with 0.5wt% Cu is obtained, denoted as Cu@BiOCl(Ov)-0.5.

[0084] Embodiment 8

[0085] The embodiment provides a preparation method of a defect-rich bismuth oxychloride photocatalyst, for preparing the defect-rich bismuth oxychloride photocatalyst, and the method comprises the following steps:

[0086] Step 1, 5g polypropylene pyrrolidone and 500mg anhydrous copper acetate are dissolved in 50ml anhydrous ethanol, and stirring is carried out under the condition of a warm water bath to obtain a stirring solution, 3g ascorbic acid is added dropwise in the stirring solution and stirred for 30min to carry out reaction, a reaction solution is obtained, and the reaction solution is washed with deionized water and ethanol alternately, and then dried in a vacuum oven to obtain copper nanoparticles;

[0087] Step 2, 20mg copper nanoparticles are taken in 10ml deionized water to obtain a copper nanoparticle dispersion solution, denoted as B4;

[0088] Step 3, 200ml bismuth oxychloride carriers in A1 are put into 4.0mg copper nanoparticle dispersion solution in B4 to carry out stirring, and after stirring is completed, standing is carried out to obtain a standing solution;

[0089] Step 4, the solution after standing is freeze-dried in liquid nitrogen environment, and after freeze-drying is completed, a bismuth oxychloride photocatalyst loaded with 2.0wt% Cu is obtained, which is recorded as Cu@BiOCl(Ov)-2.0.

[0090] Comparative Example 1

[0091] The present comparative example provides a preparation method of a BiOCl material with oxygen vacancies different from Example 2, for preparing a photocatalyst with oxygen vacancies, which comprises the following steps:

[0092] Step 1, 2.425g of bismuth nitrate pentahydrate and 0.373g of potassium chloride are dissolved in 60ml of ethanol, and a magnetic stirrer is used for magnetic stirring at 500rpm / min for 2h to obtain a magnetic stirring solution;

[0093] Step 2, the magnetic stirring solution is transferred to a 100mL polytetrafluoroethylene liner for solvent thermal treatment at 160°C, and the solvent thermal treatment time is 16h to obtain a product after solvent thermal treatment;

[0094] Step 3, the product after solvent thermal treatment is taken out for 3 times of centrifugal washing, and the ethanol and deionized water are alternately washed, and after the alternate washing is completed, the product is continuously washed with deionized water for 2 times, and after the washing is completed, the product is placed in a vacuum oven at 60°C for baking for 24h to obtain a photocatalyst with oxygen vacancies, which is recorded as BiOCl(Ov).

[0095] Comparative Example 2

[0096] The difference between the present comparative example and Comparative Example 1 is that 2.425g of bismuth nitrate pentahydrate and 0.373g of potassium chloride are dissolved in a mixed solution of 40ml of ethanol and 20ml of deionized water, and a magnetic stirrer is used for magnetic stirring at 500rpm / min for 2h to obtain a magnetic stirring solution, and the magnetic stirring solution is transferred to a 100mL polytetrafluoroethylene liner for solvent thermal treatment at 160°C, and the solvent thermal treatment time is 16h to obtain a product after solvent thermal treatment, which is a photocatalyst with oxygen vacancies, which is recorded as BiOCl(Ov-1).

[0097] The ratio of ethanol to deionized water is 2:1.

[0098] Comparative Example 3

[0099] The present comparative example differs from Comparative Example 1 in 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, 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 for solvent thermal treatment at 160°C for 16 h to obtain a product after solvent thermal treatment, i.e., a photocatalyst with oxygen vacancies, denoted as BiOCl(Ov-2).

[0100] wherein the ratio of ethanol to deionized water is 1:2.

[0101] Comparative Example 4

[0102] The present comparative example differs from Comparative Example 1 in 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, 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 for solvent thermal treatment at 160°C for 16 h to obtain a product after solvent thermal treatment, i.e., a photocatalyst with oxygen vacancies, denoted as BiOCl(Ov-2).

[0103] Application Example 1

[0104] The present embodiment provides an application of a defect-rich bismuth oxychloride photocatalyst. The bismuth oxychloride photocatalyst prepared by the above-mentioned Examples 2 to 8 and Comparative Examples 1 to 4 is applied to the preparation of acetic acid by photocatalytic reduction of carbon dioxide;

[0105] The defect-rich bismuth oxychloride photocatalyst is used to prepare acetic acid under pure water conditions;

[0106] The preparation method specifically comprises the following steps:

[0107] Step 1. 20 mg of photocatalyst and 1 magnetic stirrer 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 are placed at the bottom of a quartz cup reactor with an inner diameter of 50 mm;

[0108] Step 2. 5.0 ml of ultrapure water is taken and poured into the quartz cup, which is treated under ultrasonic conditions for 1 min to obtain a fully dispersed solution;

[0109] Step 3. The quartz cup is placed in a photocatalytic reaction kettle, and high-purity carbon dioxide is introduced to 2.0 MPa and repeatedly treated for 3 times.

[0110] Step 4, after the gas washing treatment is completed, the pressure is set to 4.0 MPa, then stirring is carried out at 50 DEG C reaction temperature, and a 300w xenon lamp is turned on;

[0111] wherein the xenon lamp is a PLS-SXE300+ / UV xenon lamp light source;

[0112] Step 5, after the reaction is completed, the reaction gas is introduced into a GC for gas phase product analysis; 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;

[0113] Step 6, the selectivity of acetic acid in the liquid phase product is calculated by a formula, and the acetic acid selectivity calculation formula is as follows:

[0114] .

[0115] In order to verify the effectiveness of the present application, Figure 1 is a SEM image of the prepared BiOCl catalyst, from which it can be seen that the synthesized BiOCl presents a regular flaky structure compared with BiOCl(Ov).

[0116] Figure 2 is a HR-TEM image of the prepared Cu@BiOCl(Ov)-1.0 catalyst. It can be seen from the above electron microscope images that the Cu nanoparticles are uniformly distributed on the BiOCl(Ov) carrier, and the size is about 5 nm.

[0117] Figure 3 is a SEM image of the prepared BiOCl(Ov), from which it can be seen that the synthesized BiOCl(Ov) presents a flaky structure, and there is a polymerization phenomenon.

[0118] Please refer to Figure 4 , Figure 4 is a HR-TEM image of the BiOCl(Ov) catalyst. Under the HR-TEM, it can be observed that there are discontinuous regions of crystal stripes on the surface of the bismuth oxychloride photocatalyst, which can verify that the surface has abundant defects.

[0119] Please refer to Figure 5 , Figure 5 is a HAADF-STEM image of the BiOCl catalyst, and the surface oxygen vacancies of the BiOCl(Ov) sample are further directly visualized by high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). The results are as follows Figure 5As shown, the (110) and (200) crystal planes intersecting the sample surface at an angle of 45° can be calibrated as the [0 0 1] region of the tetragonal lattice structure BiOCl, and the obvious surface atom vacancy phenomenon in the region is marked. In this region, the Bi and O atom arrangement of the sample is as shown in the left side of the figure Figure 5 As shown in the right side of the figure, considering that the atomic number of Bi is obviously higher than that of Cl and O, the brightness of Bi atoms in the image will be much higher than that of O atoms, and it can be speculated that the missing atoms are O atoms. At the same time, corresponding line profile analysis is carried out in the marked region, and the valley bottom with periodic Bi-O distribution can be clearly identified as a surface oxygen vacancy. In the lower right corner model, the yellow ball represents the Bi atom, and the red ball represents the O atom. Figure 5 ). Figure 6 is a high-resolution transmission electron microscopy image of Cu-loaded BiOCl. From the figure, it can be seen that Cu exists in the form of nanometer examples on the surface of the catalyst, and BiOCl still maintains a sheet structure.

[0120] Figure 7 is an element distribution map of the Cu-loaded BiOCl sample, in which red is the distribution of Bi element, purple is the distribution of Cl element, blue is the distribution of O element, and green is the distribution of Cu element. From the figure, it can be judged that Cu is uniformly loaded on the surface of the catalyst.

[0121] In Figure 8 , EPR technology is used to prove that compared with BiOCl synthesized under hydrothermal conditions, BiOCl(Ov) prepared by the ethanol solvothermal strategy is rich in surface oxygen vacancies, and in Figure 9 , XPS-O1s analysis of BiOCl synthesized by different methods is carried out, and the results also show that the surface oxygen vacancy content of BiOCl(Ov) is significantly higher than that of BiOCl.

[0122] Please refer to Figure 10 , Figure 10 is a comparison of the XRD of the catalysts prepared in Example 1, Comparative Example 1 and Comparative Example 4. In the Cu@BiOCl(Ov)-1.0 catalyst, there is no obvious Cu-related characteristic diffraction peak, indicating that the Cu NPs on the surface of the catalyst may be in a highly dispersed state.

[0123] The test results of photocatalytic reduction of carbon dioxide are shown in Figure 11 and Figure 12 It is shown that under light conditions, as the proportion of ethanol in the solution during the solvothermal process increases, the activity of the synthesized catalyst for acetic acid also increases.

[0124] Further introducing Cu NPs on the surface of BiOCl(Ov), the photocatalytic CO2 test results reflect that with the increasing of Cu loading, the activity of acetic acid in the product presents the trend of first increasing and then decreasing, and when the loading is 1.0 wt%, the activity of acetic acid is the highest, reaching 161.2 μmol / g cat / h, and the selectivity of acetic acid is 97.3%.

[0125] The photocatalytic activity test results of the catalysts in the examples and comparative examples are shown in Table 1.

[0126] Table 1:

[0127]

[0128] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0129] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. Use of a defect-rich bismuth oxychloride photocatalyst in the photocatalytic reduction of carbon dioxide to acetic acid, characterized in that, The bismuth oxychloride photocatalyst is applied to preparation of acetic acid by photocatalytic reduction of carbon dioxide. In the process of obtaining the bismuth oxychloride photocatalyst, the loading of the bismuth oxychloride photocatalyst is 0.1-2.0 wt%, and Cu is uniformly distributed in the bismuth oxychloride photocatalyst; Cu nanoparticles Cu NPs are introduced on the surface of the bismuth oxychloride carrier BiOCl(Ov) with oxygen vacancies, and the photocatalytic CO2 test results reflect that with the continuous increase of the Cu loading, the activity of acetic acid in the product presents a trend of first increasing and then decreasing, when the loading is 1.0 wt%, the activity of acetic acid is the highest, reaching 161.2 μmol / g cat / h, and the selectivity of acetic acid is 97.3%. The method further comprises the following steps: Step 1: Dissolve bismuth nitrate pentahydrate and potassium chloride in a dissolving agent to obtain a dissolved solution, wherein the dissolving agent is ethanol, a mixture of ethanol and deionized water, or a deionized water mixture solution; Step 2: Perform solvothermal treatment on the dissolved solution in a polytetrafluoroethylene liner to obtain a solvothermally treated product; Step 3: Take out the solvothermally treated product, and perform alternating washing with ethanol and deionized water, and then washing with deionized water to obtain a washed product, and then place the washed product in a vacuum oven for drying to obtain a bismuth oxychloride carrier with oxygen vacancies; Step 4: Dissolve polypropylene pyrrolidone and anhydrous copper acetate in anhydrous ethanol, and perform stirring under a warm water bath to obtain a stirring solution, drop ascorbic acid into the stirring solution to perform stirring reaction to obtain a reaction solution, and then perform alternating washing of the reaction solution with deionized water and ethanol, and then perform drying in a vacuum oven after the washing to obtain copper nanoparticles; Step 5: Take the copper nanoparticles and add deionized water to obtain a copper nanoparticle dispersion solution; Step 6: Take the bismuth oxychloride carrier and place it in the copper nanoparticle dispersion solution to perform stirring, and then stand after the stirring to obtain a standing solution; Step 7: Perform freeze-drying on the standing solution under a liquid nitrogen environment, and then obtain a bismuth oxychloride photocatalyst after the freeze-drying. 2.The application of a defect-rich bismuth oxychloride photocatalyst in photocatalytic reduction of carbon dioxide to acetic acid according to claim 1, characterized in that, In the process of obtaining the 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 the mixture of ethanol and deionized water is 1:2 or 2:1, the volume of the deionized water mixture solution is 60 ml, the stirring and dissolving time is 1-6 h, the volume of the polytetrafluoroethylene is 100 ml, the solvothermal temperature is 150-200 DEG C, the solvothermal time is 10-16 h, the number of alternating washing with ethanol and deionized water is 3 times, the number of washing with deionized water is 3 times, and the temperature of the vacuum oven is 60 DEG C. 3.The application of a defect-rich bismuth oxychloride photocatalyst in photocatalytic reduction of carbon dioxide to acetic acid according to claim 2, characterized in that, In the process of obtaining the standing solution, the mass of polypropylene pyrrolidone is 0.5-5 g, the volume of anhydrous copper acetate is 200-500 ml, the volume of anhydrous ethanol is 10-50 ml, the mass of ascorbic acid is 0.5-3 g, the drop-stirring time is 30 min, the temperature of the vacuum oven is 60 DEG C, the mass of copper nanoparticles is 5-20 mg, the ultrasonic dispersion volume of deionized water is 10 ml, the volume of the copper nanoparticle dispersion solution is 0.2-4.0 mg, and the standing time is 24 h.

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