S-type heterojunction photocatalyst and preparation method and application thereof

Abstract

The present application relates to a novel S-type heterojunction photocatalyst and its preparation method and application, and belongs to the technical field of photoelectric catalysts. The photocatalyst is composed of two-dimensional transition metal sulfide ReS2 and perovskite quantum dots CsPbBr3 with a molar ratio of 10:1 to 25:1. By measuring and calculating the conduction band and valence band positions of ReS2 and CsPbBr3, it is confirmed that they can form an S-type heterojunction structure. Compared with pure perovskite point quantum CsPbBr3, the size of CsPbBr3 in the photocatalyst is reduced, which is beneficial to increase the specific surface area of the catalyst, thereby providing more reactive sites for photocatalytic reaction. When used for photocatalytic conversion of CO2 to CO, the yield of CO is as high as 25.67 μmol / g·h. The excellent photocatalytic property makes it have good application prospect in solving the environmental problems caused by excessive emission of CO2. In addition, its preparation method is simple and suitable for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of photocatalyst technology, and relates to a novel S-type heterojunction photocatalyst, its preparation method, and its application. Background Technology

[0002] With rapid industrial development, fossil fuels such as coal, oil, and natural gas have been extensively exploited and utilized. However, while these fossil fuels have promoted the rapid development of human civilization, they have also caused massive emissions of carbon dioxide, the main greenhouse gas. Global warming, reduced food production, and rising sea levels caused by the greenhouse effect directly threaten the human living environment. Therefore, in addition to finding suitable clean energy sources, minimizing CO2 emissions and converting as much of it as possible into high-value-added chemical products such as CO2 is equally important.

[0003] The conversion of CO2 into high-value-added chemical products such as CO relies heavily on catalysts. Compared to traditional catalysts, photocatalysts have the following advantages: ① The external energy supply for the reaction is solely solar energy, which is inexhaustible; ② The reaction conditions are mild, generally at room temperature and pressure; ③ They have strong redox properties, do not exhibit adsorption saturation, and have a long lifespan. Commonly used photocatalysts for CO2 conversion include titanium dioxide, sulfides, cuprous oxide, and ferrates. However, these photocatalysts are not highly efficient at converting carbon dioxide, prompting researchers to focus on finding photocatalysts that can effectively convert CO2.

[0004] In recent years, halide perovskite materials have gained widespread attention due to their superior electrical and optical properties. Compared with most traditional photocatalysts, halide perovskite materials exhibit strong light absorption, a wide absorption range for visible light, and tunable band gaps, thus leading to their widespread application in photocatalysis. However, standalone halide perovskite CsPbBr3 exhibits a rapid carrier recombination rate, while the generation rate of photogenerated carriers under illumination is slow. To effectively suppress electron recombination, heterojunctions can be constructed.

[0005] Since there are currently no reports on ReS2 / CsPbBr3 heterojunctions as photocatalysts for carbon dioxide conversion, it is necessary to explore the efficiency of ReS2 / CsPbBr3 heterojunctions as photocatalysts for carbon dioxide conversion, thereby providing a new approach to CO2 conversion. Summary of the Invention

[0006] In view of this, one objective of the present invention is to provide a novel S-type heterojunction photocatalyst; a second objective of the present invention is to provide a method for preparing the novel S-type heterojunction photocatalyst; and a third objective of the present invention is to provide the application of the novel S-type heterojunction photocatalyst in the photocatalytic reduction of CO2.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] 1. A novel S-type heterojunction photocatalyst, wherein the novel S-type heterojunction photocatalyst is composed of a two-dimensional transition metal sulfide ReS2 and perovskite quantum dots CsPbBr3;

[0009] The molar ratio of the two-dimensional transition metal sulfide ReS2 to the perovskite quantum dot CsPbBr3 is 10:1 to 25:1.

[0010] 2. The preparation method of the novel S-type heterojunction photocatalyst is as follows:

[0011] Two-dimensional transition metal sulfide ReS2 is dispersed in toluene, and then a precursor solution of perovskite quantum dots CsPbBr3 is added. After thorough mixing, the mixture is washed with chlorobenzene, centrifuged, and dried to obtain a novel S-type heterojunction photocatalyst.

[0012] The preparation method of the precursor solution of perovskite dot quantum CsPbBr3 is as follows: Cesium bromide and lead bromide are mixed evenly, and then oleylamine, oleic acid and dimethylformamide are added to form a mixed solution. The mixed solution is stirred at 50-70°C for 60-120 min.

[0013] Preferably, the preparation method of the two-dimensional transition metal sulfide ReS2 is as follows:

[0014] Ammonium perrhenate and thiourea are dissolved in deionized water to obtain a reaction solution. The reaction solution is then transferred to a reaction vessel and hydrothermally reacted at 210–240°C for 20–24 hours to obtain the reaction product. The reaction product is washed and dried to obtain the two-dimensional transition metal sulfide ReS2.

[0015] Preferably, the mass ratio of ammonium perrhenate to thiourea is 510–560:640–710.

[0016] Preferably, the mass-to-volume ratio of the two-dimensional transition metal sulfide ReS2 and the perovskite quantum CsPbBr3 precursor solution is 40.6:487 to 46.4:220 (mg:μL); and the volume ratio of the perovskite quantum CsPbBr3 precursor solution to toluene is 1:41.48.

[0017] Preferably, the molar volume ratio of cesium bromide, lead bromide, oleylamine, oleic acid and dimethylformamide is 0.2:0.2:0.3:0.9:5, mmol:mmol:mL:mL:mL.

[0018] 3. Application of the novel S-type heterojunction photocatalyst in photocatalytic reduction of CO2.

[0019] The beneficial effects of this invention are as follows: This invention provides a novel S-type heterojunction photocatalyst. This photocatalyst is composed of two-dimensional transition metal sulfide ReS2 and perovskite quantum dots CsPbBr3 in a molar ratio of 10:1 to 25:1. Scanning electron microscopy and transmission electron microscopy results demonstrate the successful recombination of the two components. Furthermore, by measuring and calculating the conduction and valence band positions of ReS2 and CsPbBr3, it is confirmed that they can form an S-type heterojunction structure. Compared with pure perovskite quantum dots CsPbBr3, the size of the perovskite quantum dots CsPbBr3 in this photocatalyst is reduced, which is beneficial for increasing the specific surface area and providing more reactive sites for the photocatalytic reaction. In addition, it also has a wider absorption range. These excellent properties enable this photocatalyst to accelerate the separation rate of photogenerated carriers under illumination and slow down the recombination rate of photogenerated carriers, thereby helping to improve the energy efficiency of photocatalytic CO2 reduction. When this photocatalyst is used in the photocatalytic reduction of CO2, the amount of CO produced is as high as 25.67 μmol / g·h. Its photocatalytic performance is significantly better than that of a single photocatalyst, thus showing great application potential in addressing environmental problems caused by excessive CO2 emissions.

[0020] This invention also provides a novel method for preparing an S-type heterojunction photocatalyst. This method is simple and easy to operate, requires minimal equipment, is low-cost, low-energy, and suitable for large-scale production.

[0021] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0023] Figure 1 The images are SEM images of the two-dimensional transition metal sulfide ReS2 prepared in step (2) of Example 2, the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3), and the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1, where a is the SEM image of ReS2, b is the SEM image of CsPbBr3, and c is the SEM image of CsPbBr3@ReS2.

[0024] Figure 2The XRD patterns of the two-dimensional transition metal sulfide ReS2 prepared in step (2) of Example 2, the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3), and the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1 are shown, where a is the XRD pattern of ReS2, b is the XRD pattern of CsPbBr3, and c is the XRD pattern of CsPbBr3@ReS2.

[0025] Figure 3 The UV-Vis absorption spectra of the two-dimensional transition metal sulfide ReS2 prepared in step (2) of Example 2, the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3), and the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1 are shown in Figure 1. In Figure 1, a is the UV-Vis absorption spectrum of ReS2, b is the UV-Vis absorption spectrum of CsPbBr3, and c is the UV-Vis absorption spectrum of CsPbBr3@ReS2.

[0026] Figure 4 The images show the absorption curves (Tauc) of the two-dimensional transition metal sulfide ReS2 prepared in step (2) of Example 2, the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3), and the amorphous absorption curves (Tauc) of the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1, where a is the Tauc diagram of ReS2, b is the Tauc diagram of CsPbBr3, and c is the Tauc diagram of CsPbBr3@ReS2.

[0027] Figure 5 The above are X-ray photoelectron spectra (XPS) of the two-dimensional transition metal sulfide ReS2 prepared in step (2) of Example 2 and the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1, where a is the XPS image of ReS2 and b is the XPS image of CsPbBr3.

[0028] Figure 6 The images are TEM images of the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3) of Example 2 and the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1, where a is the TEM image of CsPbBr3 and b is the TEM image of CsPbBr3@ReS2.

[0029] Figure 7 This is a schematic diagram of the band arrangement of the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3) of Example 2;

[0030] Figure 8Comparison of the catalytic performance of the two-dimensional transition metal sulfide ReS2 prepared in step (2) of Example 2, the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3), and the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1.

[0031] Figure 9 The figures show a comparison of the photocatalytic performance of the novel S-type heterojunction photocatalysts prepared in Examples 1-4. Detailed Implementation

[0032] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0033] Example 1

[0034] A novel S-type heterojunction photocatalyst is proposed, which is composed of two-dimensional transition metal sulfide ReS2 and perovskite quantum dots CsPbBr3 in a molar ratio of 10:1. The specific preparation method is as follows:

[0035] (1) Preparation of the precursor solution of perovskite quantum CsPbBr3: Mix 43 mg of cesium bromide and 73.4 mg of lead bromide evenly, then add 0.3 mL of oleylamine, 0.9 mL of oleic acid and 5 mL of dimethylformamide to form a mixed solution. Transfer the mixed solution to a water bath at 60 °C and stir for 60 min to obtain the precursor solution of perovskite quantum CsPbBr3;

[0036] (2) Preparation of two-dimensional transition metal sulfide ReS2: 536 mg of ammonium perrhenate and 685 mg of thiourea were dissolved in 60 mL of deionized water to obtain a reaction solution. The reaction solution was then transferred to a reaction vessel and hydrothermally reacted at 240 °C for 24 h to obtain the reaction product. The reaction product was washed with deionized water and dried to obtain two-dimensional transition metal sulfide ReS2.

[0037] (3) Preparation of novel S-type heterojunction photocatalyst: 40.6 mg of the two-dimensional transition metal sulfide ReS2 in step (2) was placed in 20.2 mL of toluene, ultrasonically dispersed for 30 min, and then 487 μL of the perovskite dot quantum CsPbBr3 precursor solution in step (1) was added. After stirring for 30 min, the mixture was washed with chlorobenzene, centrifuged, and then dried at 70 °C to obtain the novel S-type heterojunction photocatalyst.

[0038] Example 2

[0039] A novel S-type heterojunction photocatalyst is proposed, which is composed of two-dimensional transition metal sulfide ReS2 and perovskite quantum dots CsPbBr3 in a molar ratio of 15:1. The specific preparation method is as follows:

[0040] The difference from Example 1 is that the 40.6 mg of the two-dimensional transition metal sulfide ReS2, 20.2 mL of toluene, and 487 μL of the perovskite dot quantum CsPbBr3 precursor solution in step (3) are replaced with 43.3 mg of the two-dimensional transition metal sulfide ReS2, 14.5 mL of toluene, and 350 μL of the perovskite dot quantum CsPbBr3 precursor solution in step (2).

[0041] Example 3

[0042] A novel S-type heterojunction photocatalyst is proposed, which is composed of two-dimensional transition metal sulfide ReS2 and perovskite quantum dots CsPbBr3 in a molar ratio of 20:1. The specific preparation method is as follows:

[0043] The difference from Example 1 is that the 40.6 mg of the two-dimensional transition metal sulfide ReS2, 20.2 mL of toluene, and 487 μL of the perovskite dot quantum CsPbBr3 precursor solution in step (3) are replaced with 44.8 mg of the two-dimensional transition metal sulfide ReS2, 11.2 mL of toluene, and 270 μL of the perovskite dot quantum CsPbBr3 precursor solution in step (2).

[0044] Example 4

[0045] A novel S-type heterojunction photocatalyst is proposed, which is composed of two-dimensional transition metal sulfide ReS2 and perovskite quantum dots CsPbBr3 in a molar ratio of 25:1. The specific preparation method is as follows:

[0046] The difference from Example 1 is that the 40.6 mg of the two-dimensional transition metal sulfide ReS2, 20.2 mL of toluene, and 487 μL of the perovskite dot quantum CsPbBr3 precursor solution in step (3) are replaced with 46.4 mg of the two-dimensional transition metal sulfide ReS2, 9.15 mL of toluene, and 220 μL of the perovskite dot quantum CsPbBr3 precursor solution in step (2).

[0047] Comparative Example 1

[0048] Preparation of perovskite dot quantum CsPbBr3

[0049] Mix 43 mg of cesium bromide and 73.4 mg of lead bromide evenly, then add 0.3 mL of oleylamine, 0.9 mL of oleic acid and 5 mL of dimethylformamide to form a mixed solution. Transfer the mixed solution to a water bath at 60 °C and stir for 60 min to obtain the precursor solution of perovskite quantum CsPbBr3. Take 700 mL of this precursor solution and add it dropwise to 29 mL of toluene. Stir continuously for 30 min, then wash with toluene and centrifuge.

[0050] Scanning electron microscopy (SEM) was performed on the two-dimensional transition metal sulfide ReS2 prepared in step (2) of Example 2, the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3), and the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1. The experimental results are as follows: Figure 1 As shown in the figure, ReS2 has a layered porous surface structure with a very rich surface morphology (e.g., Figure 1 As shown in Figure a), CsPbBr3 is granular (as shown in Figure a). Figure 1 As shown in Figure b), ReS2 can provide attachment sites for CsPbBr3. The theory and practice are consistent; scanning electron microscopy results show that granular perovskite dot quanta of CsPbBr3 can be relatively uniformly attached to the porous ReS2, confirming the successful composite of the two (as shown in Figure b). Figure 1 (as shown in c).

[0051] X-ray powder diffraction tests were performed on the two-dimensional transition metal sulfide ReS2 prepared in step (2) of Example 2, the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3), and the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1. The experimental results are as follows: Figure 2 As shown. From Figure 2 As shown in a and b, the positions of the diffraction peaks of ReS2 and CsPbBr3 are consistent with those on the standard card, proving the successful synthesis of ReS2 and CsPbBr3; from Figure 2As can be seen in Figure c, both ReS2 and CsPbBr3 diffraction peaks are present, indicating that CsPbBr3 is attached to the surface of ReS2.

[0052] The two-dimensional transition metal sulfide ReS2 prepared in step (2) of Example 2, the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3), and the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1 were subjected to UV-Vis absorption tests. The experimental results are as follows: Figure 3 As shown. The absorption range of ReS2 extends to the far-infrared (e.g., Figure 3 As shown in Figure a), the absorption wavelength of perovskite dot quantum CsPbBr3 is less than 520 nm (as shown in Figure a). Figure 3 As shown in Figure b), when the two are combined, the absorption range is expanded (e.g., Figure 3 (as shown in c), which is more conducive to the photocatalytic reduction of CO2.

[0053] The two-dimensional transition metal sulfide ReS2 prepared in step (2) of Example 2, the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3), and the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1 were subjected to amorphous absorption tests. The experimental results are as follows: Figure 4 As shown. The bandgap of ReS2 is 1.57 eV (as shown). Figure 4 As shown in Figure a), the band gap of CsPbBr3 is 2.30 eV (as shown in Figure a). Figure 4 (As shown in b). However, the band gap of CsPbBr3@ReS2 is 2.03 eV (as shown in b). Figure 4 As shown in Figure c), compared with pure perovskite dot quantum CsPbBr3, its band gap is reduced by 0.27 eV, indicating that there is a strong electrostatic attraction and interaction between ReS2 and CsPbBr3 during the hybridization process.

[0054] X-ray photoelectron spectroscopy (XPS) was performed on the two-dimensional transition metal sulfide ReS2 prepared in step (2) of Example 2 and the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1. The experimental results are as follows: Figure 5 As shown. Test results indicate that the valence band of ReS2 is located at 1.25 eV (as shown). Figure 5 As shown in (a), from formula E g =V B -V C Calculations show that the conduction band position of ReS2 is at -0.32 eV, indicating that ReS2 alone does not satisfy the band arrangement required for photocatalytic reduction of CO2, meaning it lacks the performance for photocatalytic CO2 reduction. Similarly, the valence band position of CsPbBr3 is at 1.03 eV (e.g., ...). Figure 5As shown in Figure b), the conduction band of CsPbBr3 is calculated to be located at -1.27 eV. Based on the conduction and valence band positions of ReS2 and CsPbBr3, it can be seen that attaching CsPbBr3 to ReS2 can form an S-type heterojunction structure.

[0055] Transmission electron microscopy (TEM) was performed on the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3) of Example 2 and the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1. The experimental results are as follows: Figure 6 As shown. From Figure 6 In Figure a, it can be observed that the perovskite dot quantum CsPbBr3 in Comparative Example 1 is a regular cubic crystal with a size of 40 nm; while from... Figure 6 In Figure b, it can be observed that the size of CsPbBr3 in CsPbBr3@ReS2 prepared in step (3) of Example 2 is approximately 10 nm. That is, compared with pure perovskite dot quantum CsPbBr3, the size of CsPbBr3 in CsPbBr3@ReS2 is reduced, which is beneficial to increasing the specific surface area of ​​the catalyst, thereby providing more reactive sites for photocatalytic reactions. In addition, besides the (200) and (220) crystal planes containing CsPbBr3, the (100) crystal plane of ReS2 was also found in the figure, which indicates that CsPbBr3 is relatively uniformly attached to ReS2, further confirming the successful composite of the two.

[0056] Figure 7 This is a schematic diagram of the band structure of the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3) of Example 2. Figure 7 As can be seen, the potential for CO2 to be converted into CO is -0.52V. However, the conduction band position of ReS2 alone does not meet this potential. Only when it is combined with CsPbBr3 can the corresponding band structure meet the requirements for photocatalytic conversion of CO2 into CO.

[0057] Similarly, the novel S-type heterojunction photocatalysts prepared in Examples 1, 3, and 4 were subjected to the above tests, and similar experimental results were obtained as those for the novel S-type heterojunction photocatalyst prepared in Example 2. This demonstrates that the preparation method described in this application enables the successful recombination of CsPbBr3 and ReS2 to form an S-type heterojunction structure. Furthermore, the heterojunction catalysts with different CsPbBr3 / ReS2 ratios provide more reactive sites for the photocatalytic reaction due to the increased specific surface area, thereby improving the energy efficiency of photocatalytic CO2 reduction.

[0058] Performance testing

[0059] 1. To investigate the catalytic performance of the two-dimensional transition metal sulfide ReS2 prepared in step (2) of Example 2, the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3), and the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1.

[0060] (1) Test method: Take 10 mg of each of the two-dimensional transition metal sulfide ReS2 prepared in step (2) of Example 2, the novel S-type heterojunction photocatalyst (CsPbBr3@ReS2) prepared in step (3), and the perovskite dot quantum CsPbBr3 prepared in Comparative Example 1, and put them into photocatalytic reactors respectively. Introduce CO2 (purity of 99.99%) gas to make the reaction pressure of the reactor between 85 and 90 kPa. Then place the corresponding reactors under simulated sunlight for 3 hours and detect the CO production by chromatography column.

[0061] (2) Experimental Results: The above test results were plotted as a bar chart. The experimental results are as follows: Figure 8 As shown, ReS2's CO yield is 0 μmol / g·h because its band arrangement does not meet the potential for photocatalytic CO2 reduction, while CsPbBr3's CO yield is 2.8 μmol / g·h. However, when ReS2 and CsPbBr3 are combined to form CsPbBr3@ReS2, the photocatalytic CO2 reduction performance is the highest, with a CO yield of 25.67 μmol / g·h. This demonstrates the superiority of the composite material.

[0062] 2. To investigate the photocatalytic performance of the novel S-type heterojunction photocatalysts prepared in Examples 1-4.

[0063] The novel S-type heterojunction photocatalysts prepared in Examples 1-4 were subjected to photocatalytic performance testing using the same testing methods described above. The experimental results are as follows: Figure 9 As shown, the highest CO yield is observed when the molar ratio of two-dimensional transition metal sulfide ReS2 to perovskite quantum dot CsPbBr3 in the catalyst is 15:1, indicating that its photocatalytic performance is optimal.

[0064] In summary, this invention provides a novel S-type heterojunction photocatalyst. This photocatalyst is composed of two-dimensional transition metal sulfide ReS2 and perovskite quantum dots CsPbBr3 in a molar ratio of 10:1 to 25:1. Various testing methods demonstrate that this photocatalyst possesses characteristics such as large specific surface area, numerous reactive sites, wide absorption range, and strong absorption, which are beneficial for accelerating the separation rate of photogenerated carriers under illumination and slowing down their recombination rate, thereby contributing to improved energy efficiency in the photocatalytic reduction of CO2. When used in the photocatalytic reduction of CO2, it produces up to 25.67 μmol / g·h of CO, thus showing great promise for addressing environmental problems caused by excessive CO2 emissions.

[0065] This invention also provides a novel method for preparing an S-type heterojunction photocatalyst. This method is simple to operate, low in cost, and suitable for large-scale industrial production.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An S-type heterojunction photocatalyst, characterized in that: The S-type heterojunction photocatalyst is composed of two-dimensional transition metal sulfide ReS2 and perovskite quantum dots CsPbBr3. The molar ratio of the two-dimensional transition metal sulfide ReS2 to the perovskite quantum dot CsPbBr3 is 10:1 to 25:

1. The two-dimensional transition metal sulfide ReS2 has a layered porous surface structure.

2. The method for preparing an S-type heterojunction photocatalyst according to claim 1, characterized in that: The preparation method is as follows: Two-dimensional transition metal sulfide ReS2 is dispersed in toluene, and then a precursor solution of perovskite quantum dots CsPbBr3 is added. After thorough mixing, the mixture is washed with chlorobenzene, centrifuged, and dried to obtain an S-type heterojunction photocatalyst. The preparation method of the precursor solution of the perovskite quantum dot CsPbBr3 is as follows: Cesium bromide and lead bromide are mixed evenly, and then oleylamine, oleic acid and dimethylformamide are added to form a mixed solution. The mixed solution is stirred at 50~70°C for 60~120 min.

3. The preparation method according to claim 2, characterized in that: The preparation method of the two-dimensional transition metal sulfide ReS2 is as follows: Ammonium perrhenate and thiourea are dissolved in deionized water to obtain a reaction solution. The reaction solution is then transferred to a reaction vessel and hydrothermally reacted at 210-240°C for 20-24 hours to obtain the reaction product. The reaction product is washed and dried to obtain the two-dimensional transition metal sulfide ReS2.

4. The preparation method according to claim 3, characterized in that: The mass ratio of ammonium perrhenate to thiourea is 510~560:640~710.

5. The preparation method according to claim 2, characterized in that: The mass-to-volume ratio of the precursor solution of the two-dimensional transition metal sulfide ReS2 and the perovskite quantum dot CsPbBr3 is 40.6:487~46.4:220 (mg:μL); the volume ratio of the precursor solution of the perovskite quantum dot CsPbBr3 to toluene is 1:41.

48.

6. The preparation method according to claim 2, characterized in that: The molar volume ratio of cesium bromide, lead bromide, oleylamine, oleic acid, and dimethylformamide is 0.2:0.2:0.3:0.9:5, mmol:mmol:mL:mL:mL.

7. The application of the S-type heterojunction photocatalyst according to claim 1 in the photocatalytic reduction of CO2.

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