A copper-doped Cs2NaBiCl6 photocatalyst, a preparation method thereof and application thereof in photocatalytic reduction of carbon dioxide

Abstract

The application belongs to the technical field of photocatalytic materials, and particularly relates to a copper-doped Cs2NaBiCl6 photocatalyst, a preparation method thereof and application thereof in photocatalytic reduction of carbon dioxide. The preparation method comprises the following steps: dissolving cesium chloride, bismuth chloride, sodium chloride and copper chloride in dimethyl sulfoxide to obtain a precursor solution; and then injecting the mixed solution into isopropyl alcohol to obtain the copper-doped Cs2NaBiCl6 photocatalyst by using an anti-solvent crystallization method. Compared with a pure-phase substrate without doping, the copper-doping modification can significantly improve the catalytic activity of the Cs2NaBiCl6 photocatalyst in photocatalytic reduction of carbon dioxide, and the carbon monoxide generation rate reaches 18.06 mu mol* g ‑1 •h ‑1 .

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to a copper-doped Cs2NaBiCl6 photocatalyst, its preparation method, and its application in the photocatalytic reduction of carbon dioxide. 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 uses inexhaustible solar energy to directly convert carbon dioxide gas into hydrocarbon solar fuels, making it a feasible method to simultaneously address the energy crisis and environmental pollution.

[0003] Cs₂NaBiCl₆, as a lead-free bismuth-based halide perovskite photocatalyst, possesses advantages such as environmental friendliness, stable and ordered crystal structure, readily available raw materials, and simple preparation process. However, its intrinsic wide bandgap means it only responds to ultraviolet light, and in the pure-phase state, the recombination rate of photogenerated carriers is high, resulting in relatively low photocatalytic activity for CO₂ reduction. Bismuth-based halide perovskites still have significant shortcomings in CO₂ reduction: pure-phase perovskites have insufficient ability to capture and activate CO₂, and poor CO₂ adsorption and activation performance; simultaneously, low carrier separation efficiency and short lifetime, along with the easy recombination of photogenerated electrons and holes, lead to a limited number of carriers participating in the catalytic reaction. These factors collectively limit the potential of bismuth-based perovskites in CO₂ reduction and urgently need to be addressed.

[0004] Copper, as an environmentally friendly and low-cost transition metal, possesses excellent catalytic activity. By doping with copper ions, the electronic structure of the material can be effectively modulated, promoting the separation of photogenerated electrons and holes, reducing recombination losses, and optimizing interfacial catalytic kinetics, thereby significantly improving the photocatalytic reduction of CO2 reactivity, while the material still maintains good stability for gas-solid phase recycling.

[0005] Therefore, the preparation of copper-doped Cs2NaBiCl6 photocatalysts is expected to improve carrier separation efficiency and interfacial catalytic performance, thereby enhancing the activity and durability of CO2 photocatalytic reduction. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing a copper-doped Cs₂NaBiCl₆ photocatalyst, its preparation method, and its application in the photocatalytic reduction of carbon dioxide. The method is simple, convenient, low-cost, and operates under mild conditions, which is conducive to large-scale production. The obtained copper-doped Cs₂NaBiCl₆ photocatalyst exhibits excellent photocatalytic reduction activity for carbon dioxide.

[0007] To solve the above problems, the technical solution of the present invention is as follows: a copper-doped Cs₂NaBiCl₆ photocatalyst, wherein Cu in the copper-doped Cs₂NaBiCl₆ photocatalyst... 2+ with Na + The molar ratio is 1:5-5:9.

[0008] A method for preparing a copper-doped Cs₂NaBiCl₆ photocatalyst includes the following steps.

[0009] Cesium chloride, bismuth chloride, sodium chloride, and copper chloride were dissolved in dimethyl sulfoxide and stirred to obtain a precursor solution. The mixed solution was then injected into isopropanol under high-speed stirring. After standing, the supernatant was discarded, and the solution was centrifuged, washed, and vacuum dried to obtain a copper-doped Cs2NaBiCl6 photocatalyst.

[0010] A method for preparing a copper-doped Cs₂NaBiCl₆ photocatalyst, wherein sodium chloride:cesium chloride:bismuth chloride:dimethyl sulfoxide:isopropanol = 0.5~0.9 mmol:1~3 mmol:0.5~1.5 mmol:4~6 ml:249~251 ml.

[0011] A method for preparing a copper-doped Cs2NaBiCl6 photocatalyst involves stirring in dimethyl sulfoxide for 50 min, stirring in isopropanol for 10 min, and allowing it to stand for 15 min. The washing is performed with ethanol three times, and the vacuum drying is carried out at 80°C for 12 h.

[0012] Application of the aforementioned copper-doped Cs2NaBiCl6 photocatalyst in the photocatalytic reduction of carbon dioxide.

[0013] The application of the copper-doped Cs2NaBiCl6 photocatalyst in the photocatalytic reduction of carbon dioxide is as follows: Under visible light irradiation, the copper-doped Cs2NaBiCl6 photocatalyst and deionized water are placed in a sealed space filled with carbon dioxide gas to reduce carbon dioxide gas to carbon monoxide gas.

[0014] The beneficial effects of this invention are as follows.

[0015] 1. This invention utilizes an anti-solvent method to prepare a copper-doped Cs2NaBiCl6 photocatalyst. This material can improve the carrier separation efficiency, thereby achieving the purpose of enhancing photocatalytic activity.

[0016] 2. This invention utilizes an antisolvent method to prepare a copper-doped Cs2NaBiCl6 photocatalyst. Cs2NaBiCl6, as a lead-free bismuth-based halide double perovskite photocatalyst, is lead-free, low in toxicity, and readily available. Its three-dimensional ordered crystal framework exhibits good chemical stability. Introducing copper ions for lattice doping can modulate the electronic band structure of the material, effectively suppressing photogenerated electron-hole recombination, improving carrier separation efficiency, and simultaneously increasing surface catalytic active sites, significantly enhancing the photoreduction reaction activity of carbon dioxide. Furthermore, the modified material still possesses excellent gas-solid phase cycling stability.

[0017] 3. The copper-doped Cs2NaBiCl6 photocatalyst prepared by this invention has stronger photocatalytic reduction ability, participates in catalytic reactions, and has good photocatalytic reduction performance of carbon dioxide. Moreover, the method is simple, convenient, low-cost, mild, and conducive to large-scale production. Attached Figure Description

[0018] Figure 1 XRD patterns of CNBC, 10Cu-CNBC, 20Cu-CNBC, 30Cu-CNBC, and 50Cu-CNBC.

[0019] Figure 2 This is a SEM chart from CNBC.

[0020] Figure 3 SEM image of 20Cu-CNBC.

[0021] Figure 4 EDS plot of 20Cu-CNBC.

[0022] Figure 5 Comparison of photocatalytic reduction of carbon dioxide reactions for CNBC, 10Cu-CNBC, 20Cu-CNBC, 30Cu-CNBC, and 50Cu-CNBC.

[0023] Figure 6 A comparison of the photocatalytic reduction activities of CNBC, 10Cu-CNBC, 20Cu-CNBC, 30Cu-CNBC, and 50Cu-CNBC.

[0024] Figure 7 PL diagrams for CNBC, 10Cu-CNBC, 20Cu-CNBC, 30Cu-CNBC, and 50Cu-CNBC. Detailed Implementation

[0025] Example 1: Preparation of Cs2NaBiCl6.

[0026] 2 mmol of cesium chloride, 1 mmol of bismuth chloride and 0.9 mmol of sodium chloride were dissolved in 5 mL of dimethyl sulfoxide and stirred for 50 min. Then the solution was poured into 250 mL of isopropanol with high speed stirring and stirred for 10 min. After standing for 15 min, the supernatant was discarded and centrifuged. The solution was washed three times with anhydrous ethanol and finally dried in a vacuum oven at 80 °C for 12 h to obtain Cs2NaBiCl6 (denoted as CNBC).

[0027] Example 2: A copper-doped Cs2NaBiCl6 photocatalyst 10Cu-CNBC (molar ratio of copper chloride to sodium chloride is 1:9).

[0028] 2 mmol of cesium chloride, 1 mmol of bismuth chloride, 0.9 mmol of sodium chloride, and 0.1 mmol of copper chloride were dissolved in 5 mL of dimethyl sulfoxide and stirred for 50 min. Then, the solution was poured into 250 mL of isopropanol under high-speed stirring and stirred for 10 min. After standing for 15 min, the supernatant was discarded, and the solution was centrifuged and washed three times with anhydrous ethanol. Finally, the solution was placed in a vacuum oven and dried at 80 °C for 12 h to obtain the copper-doped Cs2NaBiCl6 photocatalyst (denoted as 10Cu-CNBC).

[0029] The CNBC and 10Cu-CNBC prepared in Examples 1 and 2 were subjected to XRD and PL tests, and the test results are as follows: Figure 1 and Figure 7 As shown, from Figure 1 The results show that typical characteristic peaks of CNBC and Cu were detected in 10Cu-CNBC, indicating the successful preparation of 10Cu-CNBC.

[0030] Example 310: Photocatalytic reduction of carbon dioxide using Cu-CNBC photocatalyst.

[0031] The 10Cu-CNBC photocatalyst prepared in Example 2 was used to conduct a photocatalytic reduction experiment of carbon dioxide. The test procedure was as follows: using a 300W xenon lamp as the light source, 0.01g of the prepared CNBC and 10Cu-CNBC were placed in a sealed reaction vessel along with 1mL of deionized water. The sealed vessel was evacuated using a vacuum pump, and carbon dioxide gas was passed through it three times. Then, carbon dioxide was reduced under visible light irradiation. Figure 5 , 6 As shown, the copper-doped Cs₂NaBiCl₆ photocatalyst prepared in Example 2 exhibits good photocatalytic activity and stability, with a carbon monoxide generation rate of 11.99 μmol•g in 10Cu-CNBC. -1 •h -1 The carbon monoxide formation rate of CNBC is only 7.77 μmol•g. -1 •h -1 .

[0032] Example 4: A copper-doped Cs2NaBiCl6 photocatalyst 20Cu-CNBC (molar ratio of copper chloride to sodium chloride is 2:8).

[0033] 2 mmol of cesium chloride, 1 mmol of bismuth chloride, 0.8 mmol of sodium chloride and 0.2 mmol of copper chloride were dissolved in 5 mL of dimethyl sulfoxide and stirred for 50 min. Then, the solution was poured into 250 mL of isopropanol under high-speed stirring and stirred for 10 min. After standing for 15 min, the supernatant was discarded and the solution was centrifuged. The solution was washed three times with anhydrous ethanol and then dried in a vacuum oven at 80 °C for 12 h to obtain the copper-doped Cs2NaBiCl6 photocatalyst (denoted as 20Cu-CNBC).

[0034] The 20Cu-CNBC prepared in Example 4 was subjected to XRD and PL tests, and the test results are as follows: Figure 1 and Figure 7 As shown, from Figure 1 The results show that typical characteristic peaks of CNBC and Cu were detected in 20Cu-CNBC, indicating the successful preparation of 20Cu-CNBC.

[0035] CNBC and 20Cu-CNBC were tested using SEM and EDS, such as Figure 2 , Figure 3 and Figure 4 As shown, CNBC consists only of rounded, near-spherical nanoparticles, which are tightly aggregated and have a uniform morphology. 20Cu-CNBC simultaneously contains both original spherical particles and layered second-phase crystals, with the two structures interspersed and distributed, resulting in a more loosely packed structure. The spherical particles are tightly attached to the surface of the layers without phase separation, and the presence of EDS elements further confirms the successful composite formation of 20Cu-CNBC.

[0036] Example 5: Photocatalytic reduction of carbon dioxide using 20Cu-CNBC photocatalyst.

[0037] The 20Cu-CNBC photocatalyst prepared in Example 4 was used to conduct a photocatalytic reduction experiment of carbon dioxide. The test procedure was as follows: using a 300W xenon lamp as the light source, 0.01g of the prepared CNBC and 20Cu-CNBC were placed in a sealed reaction vessel along with 1mL of deionized water. The sealed vessel was evacuated using a vacuum pump, and carbon dioxide gas was passed through it three times. Then, carbon dioxide was reduced under visible light irradiation. Figure 5 , 6 As shown, the copper-doped Cs₂NaBiCl₆ photocatalyst prepared in Example 4 exhibits good photocatalytic activity and stability, with a carbon monoxide generation rate of 18.06 μmol·g⁻¹ in 20Cu-CNBC. -1 •h-1 The carbon monoxide formation rate of CNBC is only 7.77 μmol•g. -1 •h -1 .

[0038] Example 6: A copper-doped Cs2NaBiCl6 photocatalyst 30Cu-CNBC (molar ratio of copper chloride to sodium chloride is 3:7).

[0039] 2 mmol of cesium chloride, 1 mmol of bismuth chloride, 0.7 mmol of sodium chloride, and 0.3 mmol of copper chloride were dissolved in 5 mL of dimethyl sulfoxide and stirred for 50 min. Then, the solution was poured into 250 mL of isopropanol under high-speed stirring and stirred for 10 min. After standing for 15 min, the supernatant was discarded, and the solution was centrifuged. The solution was washed three times with anhydrous ethanol and then dried in a vacuum oven at 80 °C for 12 h to obtain the copper-doped Cs2NaBiCl6 photocatalyst (denoted as 30Cu-CNBC).

[0040] The 30Cu-CNBC prepared in Example 6 was subjected to XRD and PL tests, and the test results are as follows: Figure 1 and Figure 7 As shown, from Figure 1 The results show that typical characteristic peaks of CNBC and Cu were detected in 30Cu-CNBC, indicating the successful preparation of 30Cu-CNBC.

[0041] Example 7: Photocatalytic reduction of carbon dioxide using 30Cu-CNBC photocatalyst.

[0042] The 30Cu-CNBC photocatalyst prepared in Example 6 was used to conduct a photocatalytic reduction experiment of carbon dioxide. The test procedure was as follows: using a 300W xenon lamp as the light source, 0.01g of the prepared CNBC and 30Cu-CNBC were placed in a sealed reaction vessel along with 1 mL of deionized water. The sealed vessel was evacuated using a vacuum pump, and carbon dioxide gas was passed through it three times. Then, carbon dioxide was reduced under visible light irradiation. Figure 5 , 6 As shown, the copper-doped Cs₂NaBiCl₆ photocatalyst prepared in Example 6 exhibits good photocatalytic activity and stability, with a carbon monoxide generation rate of 12.57 μmol•g in 30Cu-CNBC. -1 •h -1 The carbon monoxide formation rate of CNBC is only 7.77 μmol•g. -1 •h -1 .

[0043] Example 8: A copper-doped Cs2NaBiCl6 photocatalyst (the molar ratio of copper chloride to sodium chloride is 5:5).

[0044] 2 mmol of cesium chloride, 1 mmol of bismuth chloride, 0.5 mmol of sodium chloride, and 0.5 mmol of copper chloride were dissolved in 5 mL of dimethyl sulfoxide and stirred for 50 min. Then, the solution was poured into 250 mL of isopropanol under high-speed stirring and stirred for 10 min. After standing for 15 min, the supernatant was discarded, and the solution was centrifuged. The solution was washed three times with anhydrous ethanol and then dried in a vacuum oven at 80 °C for 12 h to obtain the copper-doped Cs2NaBiCl6 photocatalyst (denoted as 50Cu-CNBC).

[0045] The 50Cu-CNBC prepared in Example 8 was subjected to XRD and PL tests, and the test results are as follows: Figure 1 and Figure 7 As shown, from Figure 1 The results show that typical characteristic peaks of CNBC and Cu were detected in 50Cu-CNBC, indicating the successful preparation of 50Cu-CNBC.

[0046] Example 9: Photocatalytic reduction of carbon dioxide using 50Cu-CNBC photocatalyst.

[0047] The 50Cu-CNBC photocatalyst prepared in Example 8 was used to conduct a photocatalytic reduction experiment of carbon dioxide. The test procedure was as follows: using a 300W xenon lamp as the light source, 0.01g of the prepared CNBC and 50Cu-CNBC were placed in a sealed reaction vessel along with 1 mL of deionized water. The sealed vessel was evacuated using a vacuum pump, and carbon dioxide gas was passed through it three times. Then, carbon dioxide was reduced under visible light irradiation. Figure 5 , 6 As shown, the copper-doped Cs₂NaBiCl₆ photocatalyst prepared in Example 8 exhibits good photocatalytic activity and stability, with a carbon monoxide generation rate of 9.90 μmol•g in 50Cu-CNBC. -1 •h -1 The carbon monoxide formation rate of CNBC is only 7.77 μmol•g. -1 •h -1 .

Claims

1. A copper-doped Cs₂NaBiCl₆ photocatalyst, characterized in that, In copper-doped Cs₂NaBiCl₆ photocatalysts, Cu 2+ with Na + The molar ratio is 1:5-5:

9.

2. A method for preparing the copper-doped Cs₂NaBiCl₆ photocatalyst according to claim 1, characterized in that, Includes the following steps: Cesium chloride, bismuth chloride, sodium chloride, and copper chloride were dissolved in dimethyl sulfoxide and stirred to obtain a precursor solution. The mixed solution was then injected into isopropanol under high-speed stirring. After standing, the supernatant was discarded, and the solution was centrifuged, washed, and vacuum dried to obtain a copper-doped Cs2NaBiCl6 photocatalyst.

3. The method for preparing the copper-doped Cs₂NaBiCl₆ photocatalyst according to claim 2, characterized in that... Sodium chloride:Cesium chloride:Bismuth chloride:Dimethyl sulfoxide:Isopropanol = 0.5~0.9mmol:1~3mmol:0.5~1.5mmol:4~6ml:249~251ml.

4. The method for preparing the copper-doped Cs₂NaBiCl₆ photocatalyst according to claim 2, characterized in that, The stirring time in dimethyl sulfoxide was 50 min, the stirring time in isopropanol was 10 min, the standing time was 15 min, the washing was done with ethanol, the washing was done 3 times, and the vacuum drying temperature was 80℃ for 12 h.

5. The application of the copper-doped Cs2NaBiCl6 photocatalyst according to claim 1 in the photocatalytic reduction of carbon dioxide.

6. The application according to claim 5, characterized in that, The method is as follows: Under visible light irradiation, copper-doped Cs2NaBiCl6 photocatalyst and deionized water are placed in a sealed space filled with carbon dioxide gas to reduce carbon dioxide gas to carbon monoxide gas.

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