A cesium copper bromide-silver bromide heterojunction photocatalyst, a preparation method and application thereof

Abstract

The application discloses a cesium copper bromide-silver bromide heterojunction photocatalyst and a preparation method and application thereof, and belongs to the technical field of photocatalytic material for preventing and treating air pollution. The preparation method comprises the following steps: dissolving cesium bromide and copper bromide in dimethyl sulfoxide, and obtaining cesium copper bromide by using an anti-solvent recrystallization method; dispersing the cesium copper bromide into an isopropyl alcohol solution, adding a silver nitrate-isopropyl alcohol solution, sealing the obtained mixed solution, continuously stirring under light irradiation, and obtaining the cesium copper bromide-silver bromide heterojunction photocatalyst through centrifugation, washing and drying. The cesium copper bromide-silver bromide heterojunction photocatalyst provided by the application has stronger photocatalytic reduction capacity, and can greatly improve the activity of the cesium copper bromide-silver bromide in photocatalytic reduction of carbon dioxide.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials for the prevention and control of air pollution, specifically relating to a cesium copper bromide-silver bromide 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 directly convert carbon dioxide gas into hydrocarbon solar fuels, representing a feasible method to simultaneously address the energy crisis and environmental pollution. Therefore, halide perovskites, as a new class of semiconductor photocatalysts, have attracted significant research interest in this field due to their excellent photoelectric properties, tunable band gaps, quantum dot size effects, and high carrier mobility. To overcome the lead toxicity of traditional lead-based perovskites, much research has focused on developing lead-free perovskite materials. Recently, copper-based Cs₂CuBr₄ perovskite has been identified as a promising candidate to replace lead-based perovskites because of its more negative conduction band potential, superior carbon dioxide adsorption capacity, and non-toxic properties. Despite its great potential in photocatalysis, photoinduced electrochemical oxidation (ECO) remains a significant challenge. - -h + The rapid recombination of the two components results in unsatisfactory efficiency of carbon dioxide reduction reaction of Cs2CuBr4 alone. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a cesium copper bromide-silver bromide heterojunction photocatalyst, its preparation method, and its application in the photocatalytic reduction of carbon dioxide. This invention utilizes an in-situ photo-assisted silver ion insertion method to construct a cesium copper bromide-silver bromide heterojunction, which can improve carrier separation efficiency, thereby enhancing the photocatalytic reduction activity of carbon dioxide.

[0004] The technical solution adopted in this invention is: a cesium copper bromide-silver bromide heterojunction photocatalyst, the preparation method of which includes: dispersing cesium copper bromide in isopropanol, adding an isopropanol solution of silver nitrate, sealing the resulting mixed solution, continuously stirring under light irradiation, centrifuging, washing and drying after the reaction is completed to obtain the cesium copper bromide-silver bromide heterojunction photocatalyst.

[0005] Furthermore, by mass ratio, cesium copper bromide : silver nitrate = 100 : (4-8).

[0006] Furthermore, the mixture was stirred continuously for 0.5 h to 5 h under light conditions.

[0007] Furthermore, the preparation method of cesium copper bromide includes: dissolving cesium bromide and copper bromide in dimethyl sulfoxide (DMSO) to obtain a precursor; injecting the precursor into isopropanol, stirring vigorously for 1 min-2 min, centrifuging, washing, and drying to obtain cesium copper bromide.

[0008] Furthermore, in molar ratio, cesium bromide : copper bromide = 1 : (0.4-0.6).

[0009] Furthermore, by volume ratio, precursor:isopropanol = 1:(20-30).

[0010] This invention provides the application of a cesium copper bromide-silver bromide heterojunction photocatalyst in the photocatalytic reduction of carbon dioxide.

[0011] Further, the method is as follows: under visible light irradiation, the cesium copper bromide-silver bromide heterojunction photocatalyst is placed in a sealed space filled with carbon dioxide gas, and the carbon dioxide gas is reduced to carbon monoxide gas.

[0012] The beneficial effects of this invention are as follows:

[0013] 1. This invention utilizes an in-situ light-assisted silver ion insertion method to prepare a cesium copper bromide-silver bromide heterojunction photocatalyst. The constructed heterojunction structure effectively improves the carrier separation efficiency, thereby achieving the purpose of enhancing the photocatalytic reduction activity of carbon dioxide.

[0014] 2. This invention utilizes an in-situ photo-assisted silver ion insertion method to prepare a cesium copper bromide-silver bromide heterojunction photocatalyst. The constructed heterojunction structure has Br vacancies on the AgBr shell, which improves the adsorption capacity for carbon dioxide, thereby achieving the purpose of improving the photocatalytic reduction activity of carbon dioxide.

[0015] 3. The cesium copper bromide-silver bromide heterojunction 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

[0016] Figure 1 Cs2CuBr4, Cs2CuBr 4-x @AgBr-4、Cs2CuBr 4-x @AgBr-6 and Cs2CuBr 4-x XRD pattern of @AgBr-8.

[0017] Figure 2 Cs2CuBr4, Cs2CuBr 4-x @AgBr-4、Cs2CuBr 4-x @AgBr-6 and Cs2CuBr4-x PL image of @AgBr-8.

[0018] Figure 3 For Cs2CuBr4(a) and Cs2CuBr 4-x SEM image of @AgBr-6(b).

[0019] Figure 4 Cs2CuBr4, AgBr, Cs2CuBr 4-x @AgBr-4、Cs2CuBr 4-x @AgBr-6 and Cs2CuBr 4-x Comparison chart of the photocatalytic reduction performance of @AgBr-8 to carbon monoxide.

[0020] Figure 5 Cs2CuBr4, AgBr, Cs2CuBr 4-x @AgBr-4、Cs2CuBr 4-x @AgBr-6 and Cs2CuBr 4-x Comparison chart of the photocatalytic reduction rate of carbon dioxide to carbon monoxide using @AgBr-8. Detailed Implementation

[0021] Example 1: A cesium copper bromide-silver bromide heterojunction photocatalyst (Cs2CuBr) 4-x @AgBr-4)

[0022] (I) Preparation method

[0023] 1. Preparation of Cs2CuBr4 microcrystals

[0024] 1.0 mmol CsBr and 0.5 mmol CuBr2 were dissolved in 20 mL DMSO to obtain the Cs2CuBr4 precursor.

[0025] 4 mL of Cs₂CuBr₄ precursor was injected into 100 mL of isopropanol and stirred vigorously for 1 min. Finally, after centrifugation, washing, and drying, Cs₂CuBr₄ microcrystals were obtained.

[0026] 2. Cs2CuBr 4-x Preparation of @AgBr-4

[0027] AgNO3 was dissolved in isopropanol (IPA) to obtain an AgNO3-IPA solution with a concentration of 1 mg-mL.

[0028] 100 mg of Cs₂CuBr₄ microcrystals were dispersed in 34 mL of isopropanol (IPA), followed by the addition of 4 mL of 1 mg-mL AgNO₃-IPA solution. The resulting mixture was sealed and stirred continuously under light irradiation for 1 h to promote the formation of AgBr and bromine vacancies on the surface of Cs₂CuBr₄. After centrifugation, washing, and drying, a cesium copper bromide-silver bromide heterojunction photocatalyst was obtained, labeled Cs₂CuBr₄. 4-x @AgBr-4.

[0029] (ii) Characterization

[0030] The prepared Cs2CuBr4 and Cs2CuBr 4-x XRD tests were performed using @AgBr-4, and the results are as follows: Figure 1 .from Figure 1 As can be seen from this, Cs2CuBr 4-x The detection of typical characteristic peaks of Cs2CuBr4 and AgBr in @AgBr-4 indicates the successful preparation of Cs2CuBr. 4-x @AgBr-4.

[0031] The prepared Cs2CuBr4 and Cs2CuBr 4-x @AgBr-4 was used for PL testing, and the results are as follows: Figure 2 .from Figure 2 As can be seen from this, Cs2CuBr 4-x The PL emission peak of @AgBr-4 is lower than that of Cs2CuBr4, indicating that the introduction of AgBr can effectively improve the separation efficiency of photogenerated carriers, thereby improving photocatalytic performance.

[0032] Example 2: A cesium copper bromide-silver bromide heterojunction photocatalyst (Cs2CuBr) 4-x @AgBr-6)

[0033] (I) Preparation method

[0034] 1. Preparation of Cs2CuBr4 microcrystals

[0035] Same as Example 1.

[0036] 2. Cs2CuBr 4-x Preparation of @AgBr-6

[0037] AgNO3 was dissolved in isopropanol (IPA) to obtain an AgNO3-IPA solution with a concentration of 1 mg-mL.

[0038] 100 mg of Cs₂CuBr₄ microcrystals were dispersed in 34 mL of isopropanol (IPA), followed by the addition of 6 mL of a 1 mg-mL AgNO₃-IPA solution. The resulting mixture was sealed and stirred continuously under light irradiation for 1 h to promote the formation of AgBr and bromine vacancies on the surface of Cs₂CuBr₄. After centrifugation, washing, and drying, a cesium copper bromide-silver bromide heterojunction photocatalyst was obtained, labeled Cs₂CuBr₄. 4-x @AgBr-6.

[0039] (ii) Characterization

[0040] The prepared Cs2CuBr4 and Cs2CuBr 4-x XRD tests were performed using @AgBr-6, and the results are as follows: Figure 1 .from Figure 1 As can be seen from this, Cs2CuBr 4-x The detection of typical characteristic peaks of Cs2CuBr4 and AgBr in @AgBr-6 indicates the successful preparation of Cs2CuBr. 4-x @AgBr-6.

[0041] The prepared Cs2CuBr4 and Cs2CuBr 4-x @AgBr-6 was used for PL testing, and the results are as follows: Figure 2 .from Figure 2 As can be seen from this, Cs2CuBr 4-x The PL emission peak of @AgBr-6 is lower than that of Cs2CuBr4, indicating that the introduction of AgBr can effectively improve the separation efficiency of photogenerated carriers, thereby improving photocatalytic performance.

[0042] The prepared Cs2CuBr4 and Cs2CuBr 4-x SEM testing was performed on @AgBr-6, and the results are as follows: Figure 3 .from Figure 3 As can be seen in (a), Cs₂CuBr₄ exhibits a smooth, blocky structure. Figure 3 As can be seen in (b), Cs2CuBr 4-x The increased volume and rougher surface of @AgBr-6 indicate that Cs2CuBr 4-x Successful synthesis of @AgBr-6.

[0043] Example 3 A cesium copper bromide-silver bromide heterojunction photocatalyst (Cs2CuBr) 4-x @AgBr-8)

[0044] (I) Preparation method

[0045] 1. Preparation of Cs2CuBr4 microcrystals

[0046] Same as Example 1.

[0047] 2. Cs2CuBr 4-x Preparation of @AgBr-6

[0048] AgNO3 was dissolved in isopropanol (IPA) to obtain an AgNO3-IPA solution with a concentration of 1 mg-mL.

[0049] 100 mg of Cs₂CuBr₄ microcrystals were dispersed in 34 mL of isopropanol (IPA), followed by the addition of 8 mL of 1 mg-mL AgNO₃-IPA solution. The resulting mixture was sealed and stirred continuously under light irradiation for 1 h to promote the formation of AgBr and bromine vacancies on the surface of Cs₂CuBr₄. After centrifugation, washing, and drying, a cesium copper bromide-silver bromide heterojunction photocatalyst was obtained, labeled Cs₂CuBr₄. 4-x @AgBr-8.

[0050] (ii) Characterization

[0051] The prepared Cs2CuBr4 and Cs2CuBr 4-x XRD tests were performed using @AgBr-8, and the results are as follows: Figure 1 .from Figure 1 As can be seen from this, Cs2CuBr 4-x The detection of typical characteristic peaks of Cs2CuBr4 and AgBr in @AgBr-8 indicates the successful preparation of Cs2CuBr. 4-x @AgBr-6.

[0052] The prepared Cs2CuBr4 and Cs2CuBr 4-x @AgBr-8 was used for PL testing, and the results are as follows: Figure 2 .from Figure 2 As can be seen from this, Cs2CuBr 4-x The PL emission peak of @AgBr-8 is lower than that of Cs2CuBr4, indicating that the introduction of AgBr can effectively improve the separation efficiency of photogenerated carriers, thereby improving photocatalytic performance.

[0053] Example 4: Application of cesium copper bromide-silver bromide heterojunction photocatalyst in photocatalytic reduction of carbon dioxide.

[0054] I. Method:

[0055] Using a 300W xenon lamp as the light source, 0.03 g of Cs₂CuBr₄ and Cs₂CuBr₄ were respectively... 4-x @AgBr-4、Cs2CuBr 4-x @AgBr-6 or Cs2CuBr 4-x@AgBr-8 and 1 mL of deionized water were placed in a sealed reaction vessel. The sealed vessel was evacuated using a vacuum pump, and carbon dioxide gas was passed through it. This process was repeated three times, and then the carbon dioxide was reduced under visible light irradiation.

[0056] Depend on Figure 4 It can be seen that the cesium copper bromide-silver bromide heterojunction photocatalyst prepared in this invention exhibits good photocatalytic activity and stability. After 2 hours of irradiation, the Cs₂CuBr₂ prepared in Example 1 showed good photocatalytic activity and stability. 4-x The yield of carbon monoxide (@AgBr-4) reached 109.6 μmol g. -1 Cs2CuBr prepared in Example 2 4-x The yield of carbon monoxide (@AgBr-6) reached 199.4 μmol g. -1 Cs2CuBr prepared in Example 3 4-x The yield of carbon monoxide (@AgBr-8) reached 148.2 μmol g. -1 The yield of carbon monoxide in Cs₂CuBr₄ was only 10.4 μmol g. -1 The rate of carbon monoxide formation of AgBr is 0.

[0057] Depend on Figure 5 It can be seen that the Cs2CuBr prepared in Example 1 4-x The formation rate of carbon monoxide with AgBr-4 reached 54.8 μmol / h. -1 g -1 Cs2CuBr prepared in Example 2 4-x The formation rate of carbon monoxide using AgBr-6 reached 99.7 μmol / h. -1 g -1 Cs2CuBr prepared in Example 3 4-x The formation rate of carbon monoxide using @AgBr-8 reached 74.1 μmol / h. -1 g -1 The formation rate of carbon monoxide from Cs₂CuBr₄ is only 5.2 μmol / h. -1 g -1 The rate of carbon monoxide formation of AgBr is 0.

Claims

1. A cesium copper bromide-silver bromide heterojunction photocatalyst, characterized in that, The cesium copper bromide-silver bromide heterojunction photocatalyst is prepared by: dispersing cesium copper bromide in isopropanol, adding an isopropanol solution of silver nitrate, sealing the resulting mixed solution, continuously stirring under light irradiation, and centrifuging, washing, and drying after the reaction is completed to obtain the cesium copper bromide-silver bromide heterojunction photocatalyst.

2. The cesium copper bromide-silver bromide heterojunction photocatalyst according to claim 1, characterized in that, By mass ratio, cesium copper bromide : silver nitrate = 100 : 4-8.

3. The cesium copper bromide-silver bromide heterojunction photocatalyst according to claim 1, characterized in that, Stir continuously for 0.5 h to 5 h under light conditions.

4. A cesium copper bromide-silver bromide heterojunction photocatalyst according to claim 1, 2, or 3, characterized in that, The method for preparing cesium copper bromide includes: dissolving cesium bromide and copper bromide in dimethyl sulfoxide to obtain a precursor; injecting the precursor into isopropanol, stirring vigorously for 1 min-2 min, centrifuging, washing, and drying to obtain cesium copper bromide.

5. The cesium copper bromide-silver bromide heterojunction photocatalyst according to claim 4, characterized in that, The molar ratio of cesium bromide to copper bromide is 1:0.4-0.

6.

6. The cesium copper bromide-silver bromide heterojunction photocatalyst according to claim 4, characterized in that, By volume ratio, precursor:isopropanol = 1:20-30.

7. The application of the cesium copper bromide-silver bromide heterojunction photocatalyst according to any one of claims 1-6 in the photocatalytic reduction of carbon dioxide.

8. The application according to claim 7, characterized in that, The method is as follows: Under visible light irradiation, the cesium copper bromide-silver bromide heterojunction photocatalyst is placed in a sealed space filled with carbon dioxide gas, and the carbon dioxide gas is reduced to carbon monoxide gas.

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