A Bi2Sn2O7 / ZnCdS heterojunction photocatalyst, its preparation method and application

Abstract

The present application belongs to the technical field of photocatalytic materials, and specifically discloses a Bi2Sn2O7 / ZnCdS heterojunction photocatalyst, a preparation method and application thereof. In the Bi2Sn2O7 / ZnCdS heterojunction photocatalyst, the mass ratio of Bi2Sn2O7 and ZnCdS is 10-50:1. The preparation method comprises the following steps: adding zinc acetate, chromium acetate and thioacetamide into deionized water, mixing uniformly to prepare a precursor A, adding sodium hydroxide, and then performing a solvothermal reaction, and finally centrifuging, washing and drying to obtain the Bi2Sn2O7 / ZnCdS heterojunction photocatalyst. The preparation process of the present application is simple, easy to control and low in production cost. The prepared Bi2Sn2O7 / ZnCdS heterojunction photocatalytic material has the characteristics of high activity, good selectivity and excellent cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to a Bi2Sn2O7 / ZnCdS heterojunction photocatalyst, its preparation method, and its application. Background Technology

[0002] In recent years, massive carbon dioxide emissions have exacerbated the global greenhouse effect, leading to a series of environmental and social problems. Photocatalytic carbon dioxide reduction, utilizing inexhaustible solar energy, can convert carbon dioxide gas into hydrocarbon solar fuels, making it a feasible method to simultaneously address the energy crisis and environmental pollution. However, the practical application of this technology is limited by the development of highly efficient and stable photocatalysts.

[0003] In existing research, bismuth-based oxide Bi₂Sn₂O₇ has attracted attention in the field of photocatalysis due to its unique crystal structure. However, Bi₂Sn₂O₇ alone suffers from drawbacks such as a narrow photoresponse range and limited charge separation efficiency. On the other hand, while ZnCdS solid solution exhibits broad-spectrum absorption characteristics, its rapid carrier recombination and poor stability during photocatalysis are also prominent issues. Although some studies have attempted to combine different semiconductor materials to improve performance, the composite system of Bi₂Sn₂O₇ and ZnCdS in the field of photocatalytic carbon dioxide reduction has not yet been fully explored.

[0004] Of particular note is that existing photocatalysts generally face common problems in carbon dioxide reduction reactions, such as low selectivity and insufficient product yield. Traditional heterojunction designs often focus only on improving charge separation efficiency, while neglecting key factors such as reactant adsorption and optimization of surface catalytic sites. Therefore, developing novel heterojunction structures to achieve a synergistic improvement in light absorption, charge separation, and surface catalytic activity is crucial for advancing photocatalytic carbon dioxide reduction technology. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a Bi₂Sn₂O₇ / ZnCdS heterojunction photocatalyst, its preparation method, and its applications. This invention improves the photocatalytic reduction efficiency of carbon dioxide by introducing a heterojunction structure composed of Bi₂Sn₂O₇ and ZnCdS.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is: a Bi2Sn2O7 / ZnCdS heterojunction photocatalyst, wherein the mass ratio of Bi2Sn2O7 to ZnCdS in the Bi2Sn2O7 / ZnCdS heterojunction photocatalyst is 10~50:1.

[0007] The preparation method of the above-mentioned Bi2Sn2O7 / ZnCdS heterojunction photocatalyst includes the following steps:

[0008] Step 1: Dissolve zinc acetate, chromium acetate and thioacetamide in deionized water, then stir magnetically for 10 min, add 2M sodium hydroxide to adjust the pH, and continue stirring for 0.5-1 h. Then transfer to a polytetrafluoroethylene high-pressure reactor for hydrothermal reaction. After the reaction is completed, wash with deionized water and ethanol, and vacuum dry to obtain ZnCdS.

[0009] Furthermore, in step 1, the hydrothermal reaction temperature is 160℃-200℃, and the hydrothermal reaction time is 12h-24h.

[0010] Furthermore, the mass ratio of zinc acetate, chromium acetate, and thioacetamide is 0.22:0.27:0.24.

[0011] Furthermore, the ratio of zinc acetate to sodium hydroxide is 0.22g:20mL.

[0012] Step 2: Disperse Bi(NO3)3·5H2O and SnCl4·5H2O separately in deionized water and sonicate to ensure uniform dispersion, obtaining SnCl4 solution and Bi(NO3)3 solution; Slowly add SnCl4 solution to Bi(NO3)3 solution, and after mixing evenly, adjust pH to 12 with 2M NaOH solution. Transfer the evenly mixed solution to a polytetrafluoroethylene high-pressure reactor and react at 180℃ for 12-24h. After natural cooling, wash until neutral and dry in an oven at 60℃ to obtain Bi2Sn2O7.

[0013] Further, in step 2, the mass ratio of Bi(NO3)3·5H2O to SnCl4·5H2O is 5.8:3.4.

[0014] Step 3: Dissolve ZnCdS and Bi2Sn2O7 in ethanol, and then heat and stir in a water bath until dry to obtain Bi2Sn2O7 / ZnCdS heterojunction photocatalyst.

[0015] Furthermore, in step 3, the water bath stirring and heating temperature is 85℃.

[0016] Furthermore, the drying temperature is 60-80℃, and the time is 6-24 hours.

[0017] This invention provides an application of a Bi2Sn2O7 / ZnCdS heterojunction photocatalyst in the photocatalytic reduction of carbon dioxide.

[0018] Further, the method is as follows: Under visible light irradiation, the Bi2Sn2O7 / ZnCdS heterojunction photocatalyst is placed in a sealed space filled with carbon dioxide gas, and the carbon dioxide gas is reduced to carbon monoxide gas.

[0019] The advantages of this invention are:

[0020] 1. This invention utilizes an in-situ generation method to prepare a Bi2Sn2O7 / ZnCdS heterojunction photocatalyst. After heterojunction, the carrier separation efficiency can be improved, thereby achieving the purpose of improving photocatalytic activity.

[0021] 2. This invention utilizes an in-situ generation method to prepare a Bi2Sn2O7 / ZnCdS heterojunction photocatalyst, which has stronger photocatalytic reduction ability, participates in catalytic reactions, and has good photocatalytic reduction performance of carbon dioxide. Moreover, this method is simple to operate, low in cost, mild in conditions, and conducive to large-scale production. Attached Figure Description

[0022] Figure 1 XRD patterns of Bi2Sn2O7 (BSO), ZnCdS (ZCS), and Bi2Sn2O7 / ZnCdS (ZCS / BSO);

[0023] Figure 2 SEM image of Bi2Sn2O7;

[0024] Figure 3 SEM image of ZnCdS;

[0025] Figure 4 The image shows a SEM image of Bi2Sn2O7 / ZnCdS from Example 1.

[0026] Figure 5 Comparison of the heterojunction photocatalytic reduction of carbon dioxide to CO by Bi2Sn2O7 / ZnCdS prepared in Examples 1-4 for Bi2Sn2O7 and ZnCdS;

[0027] Figure 6 Comparison of photocatalytic reduction of carbon dioxide reactions between Bi2Sn2O7 / NiAl-LDH (BLDH) and Bi2Sn2O7 / ZnCdS Detailed Implementation

[0028] Example 1: A Bi2Sn2O7 / ZnCdS heterojunction photocatalyst (10ZCD / BSO)

[0029] Preparation method of 10ZCD / BSO:

[0030] Step 1. Preparation of ZnCdS: Dissolve 0.22 g of Zn(Ac)₂·2H₂O and 0.27 g of Cd(Ac)₂·2H₂O in 30 mL of deionized water, add 0.24 g of thioacetamide, stir for 10 min, sonicate for 5 min, add 20 mL of 2M sodium hydroxide solution, and continue stirring for 0.5–1 h. Transfer to a 50 mL polytetrafluoroethylene high-pressure reactor, react at 180 °C for 12 h, cool, centrifuge, wash 3 times with water and 2 times with ethanol, and vacuum dry at 60 °C for 12 h to obtain ZnCdS.

[0031] Step 2. Preparation of Bi₂Sn₂O₇: Dissolve Bi(NO₃)₃·5H₂O (4.85 g) in 20 mL of deionized water and stir magnetically until transparent to obtain Bi(NO₃)₃ solution; dissolve SnCl₄·5H₂O (3.51 g) in 30 mL of deionized water and stir until completely dissolved to obtain SnCl₄ solution. Gradually add SnCl₄ solution to Bi(NO₃)₃ solution dropwise while stirring continuously, and simultaneously add 2 M NaOH solution to adjust pH to 12. A latex-like precipitate appears. Transfer the mixture to a 100 mL polytetrafluoroethylene high-pressure reactor for hydrothermal reaction (180 °C, 24 h). After the reaction, a white precipitate is obtained. Wash the sample and dry it at 60 °C for 6 h to obtain Bi₂Sn₂O₇.

[0032] Step 3. Preparation of 10ZCD / BSO: Bi2Sn2O7:ZnCdS is dissolved in ethanol at a mass percentage of 10:1, and heated in a water bath at 85°C with stirring until dry to obtain 10ZCD / BSO heterojunction photocatalytic material.

[0033] Example 2: A Bi2Sn2O7 / ZnCdS heterojunction photocatalyst (20ZCD / BSO)

[0034] Preparation method of 20ZCD / BSO:

[0035] Step 1. Preparation of ZnCdS: Same as in Example 1

[0036] Step 2. Preparation of Bi2Sn2O7: Same as in Example 1

[0037] Step 3. Preparation of 20ZCD / BSO: Bi2Sn2O7 and ZnCdS were dissolved in ethanol at a mass percentage of Bi2Sn2O7:ZnCdS=20:1. The mixture was heated in a water bath at 85°C with stirring until dry to obtain 20ZCD / BSO heterojunction photocatalytic material.

[0038] Example 3: A Bi2Sn2O7 / ZnCdS heterojunction photocatalyst (30ZCD / BSO)

[0039] 30ZCD / BSO preparation method

[0040] Step 1. Preparation of ZnCdS: Same as in Example 1

[0041] Step 2. Preparation of Bi2Sn2O7: Same as in Example 1

[0042] Step 3. Preparation of 30ZCD / BSO: Bi2Sn2O7 and ZnCdS were dissolved in ethanol at a mass percentage of Bi2Sn2O7:ZnCdS=30:1. The mixture was heated and stirred in a water bath at 85°C until dry to obtain 30ZCD / BSO heterojunction photocatalytic material.

[0043] Example 4: A Bi2Sn2O7 / ZnCdS heterojunction photocatalyst (50ZCD / BSO)

[0044] Preparation method of 50ZCD / BSO

[0045] Step 1. Preparation of ZnCdS: Same as in Example 1

[0046] Step 2. Preparation of Bi2Sn2O7: Same as in Example 1

[0047] Step 3. Preparation of Bi2Sn2O7 / ZnCdS: Preparation of 50ZCD / BSO: Bi2Sn2O7 and ZnCdS were dissolved in ethanol at a mass percentage of Bi2Sn2O7:ZnCdS=50:1. The mixture was heated and stirred in a water bath at 85℃ until dry to obtain 50ZCD / BSO heterojunction photocatalytic material.

[0048] Example 5: A Bi2Sn2O7 / NiAl-LDH heterojunction photocatalyst

[0049] Bi2Sn2O7 / NiAl-LDH preparation method

[0050] Step 1. Preparation of Bi2Sn2O7: Same as in Example 2

[0051] Step 2. Preparation of Bi2Sn2O7 / NiAl-LDH: 1.5 mmol of the Bi2Sn2O7 prepared above was dissolved in 50 mL of deionized water to form a suspension. The molar ratio of Bi2Sn2O7 to nickel nitrate and aluminum nitrate was 1:2:2. The pH value was then adjusted to 10 with sodium hydroxide solution, and the mixture was stirred for 1 h. The reaction was then carried out at 180 °C for 12 h. After centrifugation and washing, the Bi2Sn2O7 / NiAl-LDH photocatalyst was obtained.

[0052] like Figure 5As shown, the Bi₂Sn₂O₇ / ZnCdS heterojunction photocatalyst prepared in this invention exhibits excellent photocatalytic activity, with a carbon monoxide generation rate of 34.13 µmol·h⁻¹ in 10BSO / ZCS. -1 The carbon monoxide formation rate of 20BSO / ZCS reached 52.16 µmol·h⁻¹. -1 The carbon monoxide production rate of 30BSO / ZCS reached 42.87 µmol·h⁻¹. -1 The carbon monoxide formation rate of 50BSO / ZCS reached 31.04 µmol·h⁻¹. -1 .

[0053] like Figure 6 As shown, comparing the carbon monoxide generation rates of Bi2Sn2O7 / ZnCdS and Bi2Sn2O7 / NiAl-LDH, the carbon monoxide generation rate of 20BSO / ZCS is higher than that of Bi2Sn2O7 / NiAl-LDH, indicating superior photocatalytic performance.

[0054] It should be noted that, unless otherwise specified, the conditions in the embodiments are conventional. Reagents or instruments whose manufacturers are not specified are all commercially available products. The above are merely preferred embodiments of the present invention, but the present invention is not limited to these specific embodiments. Those skilled in the art can make obvious improvements, changes, and modifications to some of the technical features in the foregoing embodiments without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A Bi₂Sn₂O₇ / ZnCdS heterojunction photocatalyst, characterized in that, In the Bi2Sn2O7 / ZnCdS heterojunction photocatalyst, the mass ratio of Bi2Sn2O7 to ZnCdS is 10~50:

1.

2. A method for preparing the Bi2Sn2O7 / ZnCdS heterojunction photocatalyst as described in claim 1, characterized in that, Includes the following steps: Step 1: Dissolve zinc acetate, chromium acetate and thioacetamide in deionized water, stir, add sodium hydroxide solution to adjust pH, and continue stirring for 0.5-1 h. Then transfer to a polytetrafluoroethylene high-pressure reactor for hydrothermal reaction. After the reaction is completed, wash and dry to obtain ZnCdS. Step 2: Disperse Bi(NO3)3·5H2O and SnCl4·5H2O separately in deionized water to obtain SnCl4 solution and Bi(NO3)3 solution; add SnCl4 solution dropwise to Bi(NO3)3 solution, and after mixing evenly, adjust pH to 12 with 2M NaOH solution; transfer the evenly mixed solution to a polytetrafluoroethylene high-pressure reactor, react at 180℃ for 12-24h, wash and dry to obtain Bi2Sn2O7; Step 3: Dissolve ZnCdS and Bi2Sn2O7 in ethanol, and then heat and stir in a water bath until dry to obtain Bi2Sn2O7 / ZnCdS heterojunction photocatalyst.

3. The preparation method of the Bi2Sn2O7 / ZnCdS heterojunction photocatalyst as described in claim 2, characterized in that, In step 1, the hydrothermal reaction temperature is 160℃-200℃ and the time is 12h-24h.

4. The preparation method of the Bi2Sn2O7 / ZnCdS heterojunction photocatalyst as described in claim 2, characterized in that, In step 1, the mass ratio of zinc acetate, chromium acetate, and thioacetamide is 0.22:0.27:0.24, the volume ratio of zinc acetate to sodium hydroxide solution is 0.22g:20mL, and the concentration of sodium hydroxide solution is 2M.

5. The preparation method of the Bi2Sn2O7 / ZnCdS heterojunction photocatalyst as described in claim 2, characterized in that, In step 2, the mass ratio of Bi(NO3)3·5H2O to SnCl4·5H2O is 5.8:3.

4.

6. The preparation method of the Bi2Sn2O7 / ZnCdS heterojunction photocatalyst as described in claim 2, characterized in that, In step 3, the water bath stirring and heating temperature is 85℃.

7. An application of the Bi2Sn2O7 / ZnCdS heterojunction photocatalyst as described in claim 1 for the photocatalytic reduction of CO2 to CO.

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