Preparation method and application of layered hm-c4n3 / cd s composite photocatalytic material
By preparing layered hm-C4N3/CdS composite photocatalysts, the problems of easy recombination and low transport efficiency of photogenerated carriers were solved, thereby improving the photocatalytic CO2 reduction activity and broadening the visible light response range, demonstrating excellent photocatalytic performance.
Patent Information
- Application Number
- CN202410587317.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-13
- Publication Date
- 2026-03-03
- Estimated Expiration
- 2044-05-13
AI Technical Summary
The photocatalytic CO2 reduction efficiency of existing semiconductor photocatalytic materials, such as cadmium sulfide (CdS), is limited by the rapid recombination and poor stability of photogenerated carriers, while the semi-metallic carbon nitride (hm-C4N3) monomer suffers from low photogenerated carrier transport efficiency and poor reduction ability.
By preparing layered hm-C4N3/CdS composite photocatalysts, the heterostructure strategy was used to improve the separation efficiency of photogenerated carriers and the photoresponse range, and to provide a high-speed transport channel. Bulk hm-C4N3 and CdS composites were prepared by tube furnace and ultrasonic method.
It significantly improved the photocatalytic CO2 reduction activity, broadened the visible light response range, and increased the separation efficiency of photogenerated electrons and holes, demonstrating enhanced photocatalytic performance.
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Figure CN118371258B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of photocatalytic material preparation methods, specifically to the preparation and application of a layered half-metallic carbon nitride / cadmium sulfide composite photocatalytic material, with a specific application direction of photocatalytic CO2 reduction. Background Technology
[0002] With dwindling fossil fuel reserves, seeking clean and sustainable alternative energy sources has become an urgent challenge for humanity. The combustion of fossil fuels produces large amounts of CO2, which absorbs long-wave radiation from the sun, exacerbating the greenhouse effect. Photocatalytic CO2 reduction, also known as "artificial photosynthesis," can convert CO2 into fuels such as CO and CH4, helping to simultaneously address the dual challenges of the greenhouse effect and the energy crisis. Catalysts are the core of photocatalysis technology; therefore, finding stable, efficient, and inexpensive catalysts is crucial for its development.
[0003] Among various semiconductor photocatalytic materials, cadmium sulfide (CdS) has attracted much attention due to its ideal band gap width and suitable band edge position. However, the photocatalytic CO2 reduction efficiency of CdS monomer materials is severely limited by the rapid recombination of photogenerated carriers, and its stability is poor due to photocorrosion. Half-metal materials are materials with a special band structure in which electrons exhibit metallic properties in one spin direction and semiconductor properties in the other. In recent years, g-C4N3, a similar material synthesized using g-C3N4 (triazine ring) as a framework, has attracted the attention of researchers. Compared with g-C3N4, density functional theory calculations using a 2×2 g-C4N3 supercell show that it exhibits different half-metallic properties, hence it is named half-metallic carbon nitride (hm-C4N3). hm-C4N3 possesses a certain special half-metal abundance and a wide photoresponse range. However, hm-C4N3 monomers face problems such as low photogenerated carrier transport efficiency and poor reduction ability, resulting in low photocatalytic CO2 reduction activity.
[0004] This invention prepares a layered hm-C4N3 / CdS composite photocatalyst. The heterostructure construction strategy effectively improves the photoresponse range of the material, while alleviating the problem of easy recombination of photogenerated carriers in monomer photocatalysts. It provides a high-speed channel for efficient transport of photogenerated electrons, and finally exhibits significantly improved photocatalytic CO2 reduction activity. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing layered hm-C4N3 / CdS composite photocatalytic materials. This method involves preparing bulk hm-C4N3 using a tube furnace, preparing layered hm-C4N3 using an ultrasonic method, and then combining the layered hm-C4N3 with previously synthesized CdS using an ultrasonic and oil bath method. The successful combination of layered hm-C4N3 and CdS improves the separation efficiency of photogenerated carriers, broadens the visible light response range, and ultimately exhibits enhanced photocatalytic CO2 reduction capability.
[0006] The specific technical solution for achieving the objective of this invention is as follows:
[0007] A method for preparing a layered hm-C4N3 / CdS composite photocatalytic material includes the following preparation steps:
[0008] (1) A certain mass of sodium tricyanomethanide and 1-butyl-3-methylimidazolium chloride were added to a beaker containing a certain volume of deionized water and stirred at room temperature for a certain time to obtain a colorless and transparent solution. Then, the solution was placed in a drying oven at a certain temperature to dry it thoroughly and remove the water to obtain a pale yellow oily substance. It was dissolved again with a certain volume of anhydrous ethanol, centrifuged and the liquid was evaporated twice. The above anhydrous ethanol purification steps were repeated 3 times to finally obtain a pale yellow oily substance. Then, it was placed in a tube furnace and heated to a certain temperature at a certain rate under a nitrogen atmosphere at a certain flow rate and held for a certain time to obtain a block with metallic luster hm-C4N3.
[0009] (2) The block hm-C4N3 prepared in step (1) was placed in a ball mill and ball milled for a certain time, and then washed and dried. It was ultrasonically treated for several hours with a certain volume of 1-methyl-2-pyrrolidone as solvent. After centrifugation, washing and drying, layered hm-C4N3 was obtained.
[0010] (3) Weigh a certain amount of the layered hm-C4N3 and CdS nanorods prepared in step (2) above and dissolve them in a round-bottom flask containing a certain amount of methanol. Sonicate for a period of time, treat in an oil bath at 80℃ for a period of time, wash and centrifuge, and dry at 60-80℃ to constant weight to obtain the layered hm-C4N3 / CdS composite photocatalyst.
[0011] Furthermore, in step (1), the mass of sodium tricyanomethanide is 1.1-1.2g, the mass of 1-butyl-3-methylimidazolium chloride is 1.7-1.8g, the volume of deionized water is 25-30mL, and the stirring time is 12-14h.
[0012] Furthermore, the temperature of the drying oven in step (1) is 60-80℃, and the amount of anhydrous ethanol used is 10-30mL.
[0013] Furthermore, in step (1), the nitrogen atmosphere is introduced at a flow rate of 200 mL / min, the heating rate of the tube furnace is 3-6 °C / min, the temperature is raised to 400-420 °C, and the holding time is 60-70 min.
[0014] Furthermore, in step (2), the ball mill consists of 1 ball with a diameter of 6 mm, 3 balls with a diameter of 8 mm, and 3 balls with a diameter of 10 mm. The ball milling time is 20-30 min, the amount of 1-methyl-2-pyrrolidone is 35-45 mL, and the ultrasonic time is 48-50 h.
[0015] Furthermore, the ultrasonic treatment time in step (3) is 20-30 min, and the oil bath treatment time is 24-28 h.
[0016] Furthermore, in step (3), the mass of the layered hm-C4N3 is 2.5-10 mg, the mass of CdS is 40-47.5 mg, and the amount of methanol used is 45-55 mL.
[0017] Compared with the prior art, the beneficial effects achieved by the present invention are: the present invention,
[0018] The layered hm-C4N3 / CdS composite photocatalyst prepared by this invention has a unique and uniform morphology and stable properties. Compared with existing preparation techniques, the synthesis method is simple and low-cost. It also has significant advantages in improving the separation efficiency of photogenerated electrons and photogenerated holes and broadening the visible light response range. Compared with the single catalyst, it exhibits significantly improved photocatalytic CO2 reduction performance and has good application prospects in photocatalytic CO2 reduction. Attached Figure Description
[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:
[0020] Figure 1 The images show a comparison of XRD patterns of the hm-C4N3, CdS, and layered hm-C4N3 / CdS complexes prepared in this embodiment. Compared with CdS, the crystallinity of the layered hm-C4N3 / CdS complex is reduced, while other aspects show no significant changes.
[0021] Figure 2 This is a TEM image of the layered hm-C4N3 / CdS composite prepared in this embodiment. The image shows that the CdS nanorods are tightly attached to the layered hm-C4N3.
[0022] Figure 3This image shows a comparison of the solid-state UV diffuse reflectance of the hm-C4N3, CdS, and layered hm-C4N3 / CdS composites prepared in this embodiment. It can be seen that the light absorption range of the layered hm-C4N3 / CdS composite is significantly extended compared to that of the CdS monomer.
[0023] Figure 4 The image shows a comparison of the photocurrent of the hm-C4N3 and layered hm-C4N3 / CdS composites prepared in this invention. It can be seen that the charge separation efficiency of the layered hm-C4N3 / CdS composites is significantly improved compared to the hm-C4N3 monomer.
[0024] Figure 5 This figure shows a comparison of the CO2 reduction activities of the layered hm-C4N3 / CdS complexes with different mass fractions prepared in this embodiment. As can be seen from the figure, the prepared layered hm-C4N3 / CdS complexes exhibit significantly improved performance compared to hm-C4N3, with the 15% mass fraction complex hm-CNC-15 showing the best photocatalytic activity. Detailed Implementation
[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0026] Example 1
[0027] (1) 1.13g sodium tricyanomethanide and 1.75g 1-butyl-3-methylimidazolium chloride were added to a beaker containing 30mL of deionized water and stirred at room temperature for 12h to obtain a colorless and transparent solution. Then, the solution was placed in a drying oven at 60℃ to dry thoroughly and remove water to obtain a pale yellow oily substance. It was dissolved again with 10mL of anhydrous ethanol, centrifuged and the liquid was evaporated twice. The above anhydrous ethanol purification steps were repeated 3 times to finally obtain a pale yellow oily substance. Then, it was placed in a tube furnace and heated to 400℃ at 5℃ / min under a nitrogen atmosphere with a flow rate of 200mL / min and held for 1h to obtain a metallic luster bulk hm-C4N3.
[0028] (2) The bulk hm-C4N3 prepared in step (1) was placed in a ball mill and ball milled for 30 min, then washed and dried. It was ultrasonically treated with 35 mL of 1-methyl-2-pyrrolidone as solvent for 48 h. After centrifugation, washing and drying, layered hm-C4N3 was obtained. The steel balls consisted of 1 steel ball with a particle size of 6 mm, 3 steel balls with a particle size of 8 mm, and 3 steel balls with a particle size of 10 mm.
[0029] (3) Weigh 2.5 mg of the layered hm-C4N3 and 47.5 mg of CdS nanorods prepared in step (2) above and dissolve them in a round-bottom flask containing 50 mL of methanol. Sonicate for 30 min, treat in an oil bath at 80 °C for 24 h, wash and centrifuge, and dry at 60 °C to constant weight to obtain the layered hm-C4N3 / CdS composite photocatalyst.
[0030] The activity of the sample in Example 1 was lower than that of the sample in Example 2, and also lower than that of the sample in Example 3. It had the lowest activity among the prepared layered hm-C4N3 / CdS composite photocatalysts, but was still higher than that of the hm-C4N3 monomer.
[0031] Example 2
[0032] (1) 1.13 g of sodium tricyanomethanide and 1.75 g of 1-butyl-3-methylimidazolium chloride were added to a beaker containing 30 mL of deionized water and stirred at room temperature for 12 h to obtain a colorless and transparent solution. Then, the solution was placed in a drying oven at 60 °C to dry thoroughly and remove water to obtain a pale yellow oily substance. It was dissolved again with 10 mL of anhydrous ethanol, centrifuged and the liquid was evaporated twice. The above anhydrous ethanol purification steps were repeated 3 times to finally obtain a pale yellow oily substance. Then, it was placed in a tube furnace and heated to 400 °C at 5 °C / min under a nitrogen atmosphere at a flow rate of 200 mL / min and held for 1 h to obtain a metallic luster bulk hm-C4N3.
[0033] (2) The bulk hm-C4N3 prepared in step (1) was placed in a ball mill and ball milled for 30 min, then washed and dried. It was ultrasonically treated with 35 mL of 1-methyl-2-pyrrolidone as solvent for 48 h. After centrifugation, washing and drying, layered hm-C4N3 was obtained. The steel balls consisted of 1 steel ball with a particle size of 6 mm, 3 steel balls with a particle size of 8 mm, and 3 steel balls with a particle size of 10 mm.
[0034] (3) Weigh 7.5 mg of the layered hm-C4N3 and 42.5 mg of CdS nanorods prepared in step (2) above and dissolve them in a round-bottom flask containing 50 mL of methanol. Sonicate for 30 min, treat in an oil bath at 80 °C for 24 h, wash and centrifuge, and dry at 60 °C to constant weight to obtain the layered hm-C4N3 / CdS composite photocatalyst.
[0035] The activity of the sample in Example 2 was higher than that of the sample in Example 1, and also higher than that of the sample in Example 3. It had the highest activity among the prepared layered hm-C4N3 / CdS composite photocatalysts.
[0036] Example 3
[0037] (1) 1.13g sodium tricyanomethanide and 1.75g 1-butyl-3-methylimidazolium chloride were added to a beaker containing 30mL of deionized water and stirred at room temperature for 12h to obtain a colorless and transparent solution. Then, the solution was placed in a drying oven at 60℃ to dry thoroughly and remove water to obtain a pale yellow oily substance. It was dissolved again with 10mL of anhydrous ethanol, centrifuged and the liquid was evaporated twice. The above anhydrous ethanol purification steps were repeated 3 times to finally obtain a pale yellow oily substance. Then, it was placed in a tube furnace and heated to 400℃ at 5℃ / min under a nitrogen atmosphere with a flow rate of 200mL / min and held for 1h to obtain a metallic luster bulk hm-C4N3.
[0038] (2) The bulk hm-C4N3 prepared in step (1) was placed in a ball mill and ball milled for 30 min, then washed and dried. It was ultrasonically treated with 35 mL of 1-methyl-2-pyrrolidone as solvent for 48 h. After centrifugation, washing and drying, layered hm-C4N3 was obtained. The steel balls consisted of 1 steel ball with a particle size of 6 mm, 3 steel balls with a particle size of 8 mm, and 3 steel balls with a particle size of 10 mm.
[0039] (3) Weigh 10 mg of the layered hm-C4N3 and 40 mg of CdS nanorods prepared in step (2) above and dissolve them in a round-bottom flask containing 50 mL of methanol. Sonicate for 30 min, treat in an oil bath at 80 °C for 24 h, wash and centrifuge, and dry at 60 °C to constant weight to obtain the layered hm-C4N3 / CdS composite photocatalyst.
[0040] The activity of the sample in Example 3 was lower than that of the sample in Example 2, but higher than that of the sample in Example 1, and it showed good activity in the prepared layered hm-C4N3 / CdS composite photocatalyst.
[0041] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.
Claims
1. A method for preparing a layered hm-C4N3 / CdS composite photocatalytic material for photocatalytic CO2 reduction, characterized in that, The preparation steps include the following: (1) A certain mass of sodium tricyanomethanide and 1-butyl-3-methylimidazolium chloride were added to a beaker containing a certain volume of deionized water and stirred at room temperature for a certain time to obtain a colorless and transparent solution. Then, the solution was placed in a drying oven at a certain temperature to fully dry and remove water to obtain a pale yellow oily substance. It was dissolved again with a certain volume of anhydrous ethanol, centrifuged and the liquid was evaporated twice. The above anhydrous ethanol purification steps were repeated 3 times to finally obtain a pale yellow oily substance. Then, it was placed in a tube furnace and heated to a certain temperature at a certain rate under a nitrogen atmosphere at a certain flow rate and held for a certain time to obtain a block with metallic luster hm-C4N3. (2) The block hm-C4N3 prepared in step (1) is placed in a ball mill and ball milled for 20-30 min, and then washed and dried. The ball mill consists of 1 ball with a particle size of 6 mm, 3 balls with a particle size of 8 mm, and 3 balls with a particle size of 10 mm. It is ultrasonically treated with a certain volume of 1-methyl-2-pyrrolidone as solvent for 48-50 h. After centrifugation, washing and drying, layered hm-C4N3 is obtained. (3) Weigh 2.5-10 mg of layered hm-C4N3 and 40-47.5 mg of CdS nanorods prepared in step (2) above and dissolve them in a round-bottom flask containing a certain amount of methanol. Sonicate for a period of time, treat in an oil bath at 80℃ for a period of time, wash and centrifuge, and dry at 60-80℃ to constant weight to obtain layered hm-C4N3 / CdS composite photocatalyst.
2. The method for preparing a layered hm-C4N3 / CdS composite photocatalytic material for photocatalytic CO2 reduction according to claim 1, characterized in that, In step (1), the mass of sodium tricyanomethanide is 1.1-1.2g, the mass of 1-butyl-3-methylimidazolium chloride is 1.7-1.8g, the volume of deionized water is 25-30mL, and the stirring time is 12-14h.
3. The method for preparing a layered hm-C4N3 / CdS composite photocatalytic material for photocatalytic CO2 reduction according to claim 1, characterized in that, The temperature of the drying oven in step (1) is 60-80℃, and the amount of anhydrous ethanol used is 10-30mL.
4. The method for preparing a layered hm-C4N3 / CdS composite photocatalytic material for photocatalytic CO2 reduction according to claim 1, characterized in that, In step (1), the nitrogen atmosphere is introduced at a flow rate of 200 mL / min, the heating rate of the tube furnace is 3-6℃ / min, the temperature is raised to 400-420℃, and the holding time is 60-70 min.
5. The method for preparing a layered hm-C4N3 / CdS composite photocatalytic material for photocatalytic CO2 reduction according to claim 1, characterized in that, The amount of 1-methyl-2-pyrrolidone used in step (2) is 35-45 mL.
6. The method for preparing a layered hm-C4N3 / CdS composite photocatalytic material for photocatalytic CO2 reduction according to claim 1, characterized in that, The ultrasonic treatment time in step (3) is 20-30 min, and the oil bath treatment time is 24-28 h.
7. The method for preparing a layered hm-C4N3 / CdS composite photocatalytic material for photocatalytic CO2 reduction according to claim 1, characterized in that, The amount of methanol used in step (3) is 45-55 mL.
8. The application of the photocatalytic material prepared by the preparation method according to any one of claims 1 to 7 in the photocatalytic reduction of CO2.