Low-concentration iron-doped Cs2NaBiCl6 material, preparation method and application thereof

Abstract

The application belongs to the technical field of photocatalytic materials, and particularly relates to a low-concentration iron-doped Cs2NaBiCl6 material, a preparation method and application thereof. The preparation method comprises the following steps: placing cesium chloride, bismuth chloride, sodium chloride and iron chloride into a mortar for grinding, drying, and obtaining the low-concentration iron-doped Cs2NaBiCl6 material by using a grinding method. The iron is doped into the Cs2NaBiCl6 by the grinding method, and the performance of the photocatalyst in catalyzing the reduction of carbon dioxide is effectively improved. The generation rate of carbon monoxide reaches 49.01 micromoles per gram per hour at most. ‑1 ·h ‑1 .

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to a low-concentration iron-doped Cs2NaBiCl6 material, 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 uses inexhaustible solar energy as an energy source, directly converting carbon dioxide gas into hydrocarbon solar fuels, making it a feasible method to simultaneously address the energy crisis and environmental pollution. Cs₂NaBiCl₆ is a typical lead-free double perovskite halide semiconductor material, attracting widespread attention in the scientific research field as a novel and highly efficient visible light photocatalytic material. It possesses a regular double perovskite crystal structure, with Na₂O₂ inside the crystal... + Bi 3+ With Cl - With its ordered coordination and unique halide crystal framework, Cs₂NaBiCl₆ allows for precise tuning of its band structure and optical absorption properties. This special crystal structure possesses excellent photogenerated carrier transport performance, effectively shortening charge migration paths and suppressing electron-hole recombination. Furthermore, the material itself exhibits low toxicity, strong structural tunability, and good photochemical stability and environmental adaptability. However, pure-phase Cs₂NaBiCl₆ still has certain limitations in its applications. Its photogenerated carrier separation efficiency is limited, its carbon dioxide molecule adsorption and activation ability is weak, and the interfacial charge transfer resistance during the photocatalytic reaction is relatively large, significantly restricting its large-scale practical application in the field of visible light photocatalytic carbon dioxide reduction.

[0003] Therefore, to address the performance limitations of pure-phase Cs₂NaBiCl₆, its photocatalytic performance can be optimized through precise ion doping modification strategies. Appropriate iron ion doping offers advantages such as simple processing, controllable doping sites, and excellent bandgap regulation, effectively compensating for the performance defects of pure-phase Cs₂NaBiCl₆ semiconductor materials. As a functional dopant, iron ions can not only precisely regulate the band structure of Cs₂NaBiCl₆, narrowing the band gap and broadening the visible light spectral response range, significantly improving the utilization rate of solar energy, but also construct abundant defect active sites on the crystal surface and within the crystal, significantly enhancing the material's adsorption, capture, and activation capabilities for carbon dioxide gas. Simultaneously, iron ion doping can effectively optimize carrier transport channels, reduce interfacial charge transfer resistance, effectively suppress the disordered recombination of photogenerated electron-hole pairs, and accelerate the rapid migration and efficient separation of interfacial photogenerated charges. This significantly improves the photocatalytic carbon dioxide reduction efficiency and recycling stability of iron-doped Cs₂NaBiCl₆-based materials, providing strong support for their large-scale practical application in the field of visible light catalysis. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a low-concentration iron-doped Cs2NaBiCl6 material, its preparation method, and its applications. The preparation method is simple, convenient, low-cost, and operates under mild conditions, which is conducive to large-scale production. The obtained low-concentration iron-doped Cs2NaBiCl6 material exhibits excellent photocatalytic reduction activity of carbon dioxide.

[0005] The specific solution of the present invention is as follows.

[0006] A low-concentration iron-doped Cs₂NaBiCl₆ material, wherein Fe 3+ with Na + The molar ratio is 1:4 to 1:19.

[0007] A method for preparing the above-mentioned low-concentration iron-doped Cs2NaBiCl6 material includes the following steps: grinding cesium chloride, bismuth chloride, sodium chloride and ferric chloride in a mortar and then drying to obtain the low-concentration iron-doped Cs2NaBiCl6 material.

[0008] The above-mentioned method for preparing low-concentration iron-doped Cs2NaBiCl6 material uses a molar ratio of cesium chloride:bismuth chloride:sodium chloride = 5.5~6.5:2.5~3.5:2.5~3.5.

[0009] The above-mentioned method for preparing low-concentration iron-doped Cs2NaBiCl6 material involves grinding for 1 hour, drying for 12 hours, and drying at a temperature of 80°C.

[0010] Application of the above-mentioned low-concentration iron-doped Cs2NaBiCl6 material in photocatalytic reduction of carbon dioxide.

[0011] The application of the aforementioned low-concentration iron-doped Cs2NaBiCl6 material in photocatalytic reduction of carbon dioxide is as follows: Under visible light irradiation, the low-concentration iron-doped Cs2NaBiCl6 material 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 a grinding method to prepare low-concentration iron-doped Cs2NaBiCl6 material. The doping structure of this material can improve the carrier separation efficiency, thereby achieving the purpose of improving photocatalytic activity.

[0014] 2. The present invention utilizes a grinding method to construct a low-concentration iron-doped Cs2NaBiCl6 material. Cs2NaBiCl6 has a large specific surface area, which can provide more reactive sites in photocatalytic reactions. The introduction of iron ions can form a doped structure with Cs2NaBiCl6, which is beneficial to further improve the carrier separation efficiency.

[0015] 3. The low-concentration iron-doped Cs2NaBiCl6 material 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 XRD patterns of CNBC, Fe-CNBC-1, Fe-CNBC-2, Fe-CNBC-3, and Fe-CNBC-4.

[0017] Figure 2 This is a SEM chart from CNBC.

[0018] Figure 3 This is a SEM image of Fe-CNBC-3.

[0019] Figure 4 for Figure 3 The corresponding EDS images are shown, where (a) is the EDS layered image, (b) is the Bi element, (c) is the Cs element, (d) is the Na element, (e) is the Fe element, and (f) is the Cl element.

[0020] Figure 5 Comparison of photocatalytic reduction of carbon dioxide reactions for CNBC, Fe-CNBC-1, Fe-CNBC-2, Fe-CNBC-3, and Fe-CNBC-4.

[0021] Figure 6 A comparison of the photocatalytic reduction activities of CNBC, Fe-CNBC-1, Fe-CNBC-2, Fe-CNBC-3, and Fe-CNBC-4.

[0022] Figure 7 PL diagrams for CNBC, Fe-CNBC-1, Fe-CNBC-2, Fe-CNBC-3, and Fe-CNBC-4. Detailed Implementation

[0023] Example 1: Cs2NaBiCl6 material.

[0024] 1.01 g of cesium chloride, 0.95 g of bismuth chloride and 0.18 g of sodium chloride were ground for 1 h and dried at 80 °C for 12 h to obtain Cs2NaBiCl6 (denoted as CNBC).

[0025] Example 2: A low-concentration iron-doped Cs2NaBiCl6 material (the molar ratio of ferric chloride to sodium chloride is 1:19).

[0026] 1.01g of cesium chloride, 0.95g of bismuth chloride, 0.17g of sodium chloride and 0.02g of ferric chloride were ground in a mortar and dried at 80℃ for 12h to obtain a low-concentration iron-doped Cs2NaBiCl6 material (denoted as Fe-CNBC-1).

[0027] The CNBC and Fe-CNBC-1 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 in the figure, typical characteristic peaks of Fe and CNBC were detected in Fe-CNBC-1, and the PL emission peak of Fe-CNBC-1 was lower than that of CNBC, indicating the successful preparation of Fe-CNBC-1.

[0028] Example 3: Photocatalytic reduction of carbon dioxide using Fe-CNBC-1 photocatalyst.

[0029] The CNBC and Fe-CNBC-1 photocatalysts prepared in Examples 1-2 were used to conduct photocatalytic reduction experiments of carbon dioxide. The test procedure was as follows: using a 300W xenon lamp as the light source, 0.05g of the prepared CNBC and Fe-CNBC-1 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 introduced, cyclically repeated three times. Then, carbon dioxide was reduced under visible light irradiation. The results are as follows: Figure 5 , 6 As shown, the low-concentration iron-doped Cs2NaBiCl6 material Fe-CNBC-1 prepared in Example 2 exhibits excellent photocatalytic activity and stability, with a carbon monoxide generation rate of 40.155 μmol·g⁻¹. -1 ·h -1 The carbon monoxide formation rate of CNBC is only 29.305 μmol·g. -1 ·h -1 .

[0030] Example 4: A low-concentration iron-doped Cs2NaBiCl6 material (the molar ratio of ferric chloride to sodium chloride is 1:9).

[0031] 1.01g of cesium chloride, 0.95g of bismuth chloride, 0.16g of sodium chloride and 0.05g of ferric chloride were ground in a mortar and dried at 80℃ for 12h to obtain a low-concentration iron-doped Cs2NaBiCl6 material (denoted as Fe-CNBC-2).

[0032] The CNBC and Fe-CNBC-2 prepared in Examples 1 and 4 were subjected to XRD and PL tests, and the test results are as follows: Figure 1 and Figure 7 As shown in the figure, typical characteristic peaks of Fe and CNBC were detected in Fe-CNBC-2, and the PL emission peak of Fe-CNBC-2 was lower than that of CNBC, indicating the successful preparation of Fe-CNBC-2.

[0033] Example 5: Photocatalytic reduction of carbon dioxide using Fe-CNBC-2 photocatalyst.

[0034] The Fe-CNBC-2 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, 0.05g of the prepared CNBC and Fe-CNBC-2 were placed in 1mL of deionized water into a self-made sealed reaction vessel. 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 low-concentration iron-doped Cs₂NaBiCl₆ material prepared in Example 4 exhibits excellent photocatalytic activity and stability, with the carbon monoxide generation rate of Fe-CNBC₂ reaching 43.62 μmol·g⁻¹. -1 ·h -1 The carbon monoxide formation rate of CNBC is only 29.305 μmol·g. -1 ·h -1 .

[0035] Example 6: A low-concentration iron-doped Cs2NaBiCl6 material (the molar ratio of ferric chloride to sodium chloride is 3:17).

[0036] 1.01g of cesium chloride, 0.95g of bismuth chloride, 0.15g of sodium chloride and 0.07g of ferric chloride were ground in a mortar and dried at 80℃ for 12h to obtain a low-concentration iron-doped Cs2NaBiCl6 material (denoted as Fe-CNBC-3).

[0037] The CNBC and Fe-CNBC-3 prepared in Examples 1 and 6 were subjected to XRD and PL tests, and the test results are as follows: Figure 1 and Figure 7As shown in the figure, typical characteristic peaks of Fe and CNBC were detected in Fe-CNBC-3, and the PL emission peak of Fe-CNBC-3 was lower than that of CNBC, indicating the successful preparation of Fe-CNBC-3.

[0038] The prepared CNBC and Fe-CNBC-3 were subjected to SEM testing, such as... Figure 2 , Figure 3 As shown, CNBC exhibits an irregular prismatic structure. After Fe doping, the overall grain size is larger, the grain edges are more prominent, and the intergranular gaps and pores are more obvious.

[0039] The prepared CNBC and Fe-CNBC-3 were subjected to EDS testing, such as... Figure 4 As shown, the five target elements Bi, Cs, Na, Fe, and Cl are uniformly dispersed at the micrometer scale in the sample, indicating the successful preparation of Fe-CNBC-3.

[0040] Example 7: Photocatalytic reduction of carbon dioxide using Fe-CNBC-3 photocatalyst.

[0041] The Fe-CNBC-3 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, 0.05g of the prepared CNBC and Fe-CNBC-3 were placed in 1mL of deionized water into a self-made sealed reaction vessel. 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. The results are as follows: Figure 5 , 6 As shown, the low-concentration iron-doped Cs₂NaBiCl₆ material prepared in Example 6 exhibits excellent photocatalytic activity and stability, with the carbon monoxide generation rate of Fe-CNBC-3 reaching 49.01 μmol·g⁻¹. -1 ·h -1 The carbon monoxide formation rate of CNBC is only 29.305 μmol·g. -1 ·h -1 .

[0042] Example 8: A low-concentration iron-doped Cs2NaBiCl6 material (the molar ratio of ferric chloride to sodium chloride is 1:4).

[0043] 1.01g of cesium chloride, 0.95g of bismuth chloride, 0.14g of sodium chloride and 0.1g of ferric chloride were ground in a mortar and dried at 80℃ for 12h to obtain a low-concentration iron-doped Cs2NaBiCl6 material (denoted as Fe-CNBC-4).

[0044] The CNBC and Fe-CNBC-4 prepared in Examples 1 and 8 were subjected to XRD and PL tests, and the test results are as follows: Figure 1 and Figure 7 As shown in the figure, typical characteristic peaks of Fe and CNBC were detected in Fe-CNBC-4, and the PL emission peak of Fe-CNBC-4 was lower than that of CNBC, indicating the successful preparation of Fe-CNBC-4.

[0045] Example 9: Photocatalytic reduction of carbon dioxide using Fe-CNBC-4 photocatalyst.

[0046] The Fe-CNBC-4 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, 0.05g of the prepared CNBC and Fe-CNBC-4 were placed in 1mL of deionized water into a self-made sealed reaction vessel. 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. The results are as follows: Figure 5 , 6 As shown, the low-concentration iron-doped Cs₂NaBiCl₆ material prepared in Example 8 exhibits excellent photocatalytic activity and stability, with the carbon monoxide generation rate of Fe-CNBC-4 reaching 45.07 μmol·g⁻¹. -1 ·h -1 The carbon monoxide formation rate of CNBC is only 29.305 μmol·g. -1 ·h -1 .

Claims

1. A low-concentration iron-doped Cs₂NaBiCl₆ material, characterized in that, In low-concentration iron-doped Cs₂NaBiCl₆ materials, Fe 3+ with Na + The molar ratio is 1:4 to 1:

19.

2. A method for preparing a low-concentration iron-doped Cs₂NaBiCl₆ material according to claim 1, characterized in that, Includes the following steps: Cesium chloride, bismuth chloride, sodium chloride, and ferric chloride were ground in a mortar and dried to obtain a low-concentration iron-doped Cs₂NaBiCl₆ material.

3. The method for preparing low-concentration iron-doped Cs₂NaBiCl₆ material according to claim 2, characterized in that, The molar ratio of cesium chloride:bismuth chloride:sodium chloride is 5.5~6.5:2.5~3.5:2.5~3.

5.

4. The method for preparing low-concentration iron-doped Cs₂NaBiCl₆ material according to claim 2, characterized in that, The grinding time is 1 hour, the drying time is 12 hours, and the drying temperature is 80℃.

5. The application of the low-concentration iron-doped Cs2NaBiCl6 material as described in claim 1 in the photocatalytic reduction of carbon dioxide.

6. The application of the low-concentration iron-doped Cs₂NaBiCl₆ material according to claim 5 in the photocatalytic reduction of carbon dioxide, characterized in that, The method is as follows: Under visible light irradiation, a low-concentration iron-doped Cs2NaBiCl6 material is placed in a closed space filled with carbon dioxide gas, and the carbon dioxide gas is reduced to carbon monoxide gas.

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