A method for synthesizing S-modulated Cu single-atom-supported red carbon nitride
Through the S-modulated Cu single-atom-supported red carbon nitride synthesis method, the problem of poor stability of red carbon nitride in the photocatalytic CO2 reduction process and mostly gas phase is solved, and efficient photocatalytic CO2 reduction to liquid phase products is achieved. , especially the effect of ethanol, and the process is simple and environmentally friendly.
Patent Information
- Application Number
- CN202410768854.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-14
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2044-06-14
AI Technical Summary
During the photocatalytic CO2 reduction process, red carbon nitride has problems such as photogenerated electrons and holes that are easy to recombinate, poor stability, and mostly gas phases. There are few studies on photocatalytic CO2 reduction to liquid phase products.
Using the S-modulated Cu single-atom-supported red carbon nitride synthesis method, the mixture grinding of melamine, 2,4,6-triaminopyrimidine, trimeric thiocyanic acid and potassium chloride in a mortar, the procedure is heated and calcined Cooled under N2 atmosphere, then stirred and evaporated to dryness with CuCl in ultrapure water and dried in vacuum to prepare a red carbon nitride photocatalyst supported by Cu single atoms.
The photocatalytic activity and stability of red carbon nitride is improved, the separation of photogenerated electron-holes is promoted, and electron-rich Cu sites are formed, and CO2 is successfully reduced to liquid phase products, especially ethanol, and the process is simple and environmentally friendly.
Smart Images
Figure CN118719113B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of catalytic materials, and in particular relates to a method for synthesizing a S-modulated Cu single-atom-loaded red carbon nitride system. Background Art
[0002] As a special metal-free semiconductor graphite phase carbon nitride material, it has an appropriate band gap width (E g About 2.7eV), and visible light response ability, so graphite phase carbon nitride has a good prospect in the application of photocatalytic technology. So far, graphite phase carbon nitride semiconductor photocatalysts have been mainly used for photocatalytic carbon dioxide reduction in the visible light region, photodecomposition of water to produce hydrogen, removal of pollutants in the environment, etc. However, since pure graphite phase carbon nitride has a relatively narrow visible light absorption range, people have developed a red carbon nitride to broaden the light absorption range. Despite this, red carbon nitride still has disadvantages such as easy recombination of photogenerated electrons and holes and poor stability. At the same time, the reduction products obtained by using red carbon nitride for CO2 reduction are mostly gaseous products such as CO and CH4, and there is little research on the photocatalytic reduction of CO2 to liquid products.
[0003] Therefore, modifying red carbon nitride to promote the photocatalytic reduction of CO2 to liquid products and improve stability has extremely important application value. Summary of the Invention
[0004] In order to solve the above technical problems, the present invention provides a method for synthesizing a S-modulated Cu single-atom-supported red carbon nitride system.
[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:
[0006] A method for synthesizing S-modulated Cu single-atom-supported red carbon nitride comprises the following steps:
[0007] S1. Mix melamine, 2,4,6-triaminopyrimidine, thiocyanate and potassium chloride in a mortar and grind them thoroughly according to the proportions.
[0008] S2. The mixed and ground powder is placed in a porcelain boat, and the temperature is programmed to the calcination temperature under a N2 atmosphere, calcined for a period of time, and then cooled to room temperature. After washing, S-modulated red carbon nitride is obtained;
[0009] S3. Based on the mass of the S-modulated red carbon nitride sample, the mass of the added CuCl solid is calculated according to the mass percentage of the added Cu single atom. The S-modulated red carbon nitride and the CuCl solid are mixed and stirred in ultrapure water for a period of time, and then evaporated to obtain a product; the evaporated product is washed and vacuum-dried to obtain the S-modulated Cu single atom-loaded red carbon nitride sample.
[0010] In step S1, the mass ratio of melamine, 2,4,6-triaminopyrimidine, thiocyanate and potassium chloride is 10:3:10:20, and the grinding time is 5-20 minutes.
[0011] In step S2, the calcination temperature is 500-600°C, the calcination time is 2-4 hours, and the heating rate is 4-6°C / min; and the product is cooled to room temperature by natural cooling under N2 atmosphere.
[0012] In step S3, the amount of CuCl solid added is such that the mass of Cu single atoms is 0.5-3% of the mass of the S-modulated red carbon nitride.
[0013] In step S3, the stirring time is 10-20 hours; and the evaporation temperature is 80-100°C.
[0014] In step S3, the cleaning method is: the product is filtered and washed with ultrapure water until the ion concentration is less than 20 ppm.
[0015] In step S3, the vacuum drying temperature is 50-70° C., and the drying time is 10-15 hours.
[0016] In the present invention, by modifying red carbon nitride, the prepared S-modulated Cu single-atom-loaded red carbon nitride photocatalyst is used to reduce CO2 under simulated sunlight.
[0017] The beneficial effects of the present invention are:
[0018] (1) The present invention prepares a sulfur-modulated Cu single-atom-loaded red carbon nitride material. The sulfur modulation changes the chemical structure of the red carbon nitride, which is beneficial for the loading of Cu single atoms. The preparation method has the characteristics of simple operation, simple process, and environmental protection. The obtained sulfur-modulated Cu single-atom-loaded red carbon nitride has high photocatalytic activity and good stability.
[0019] (2) The catalyst prepared by the present invention is used to reduce CO2 under visible light, absorbs light energy to generate electron-hole pairs, and S acts as an aggregation center for photogenerated holes, thereby improving the separation efficiency of photogenerated electrons and holes and promoting the formation of electron-rich Cu sites, which is beneficial to the reduction of CO2 to ethanol. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is a high-angle annular dark-field scanning transmission electron microscopy image of the product of Example 1 after spherical aberration correction;
[0021] Figure 2 This is the high-magnification X-ray photoelectron spectrum of Cu element of the product of Example 1 and S-modulated red carbon nitride;
[0022] Figure 3 This is the CO2 adsorption spectrum of the product of Example 1 and red carbon nitride modulated with S;
[0023] Figure 4 This is a comparison chart of the CO2 reduction performance of the product of Example 1 and S-modulated red carbon nitride under simulated sunlight conditions.
[0024] Figure 5 This is a comparison chart of the CO2 reduction performance of the products obtained in Examples 1-3 of the present invention under simulated sunlight conditions. DETAILED DESCRIPTION
[0025] In order to further understand the features, technical means, specific objectives and functions achieved by the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.
[0026] Example 1
[0027] A method for synthesizing S-modulated Cu single-atom-supported red carbon nitride comprises the following steps:
[0028] S1. Weigh 1.0 g of melamine, 0.3 g of 2,4,6-triaminopyrimidine, 1.0 g of thiocyanate, and 2.0 g of potassium chloride in a mortar and grind thoroughly for 10 minutes.
[0029] S2. Place the mixed and ground powder in a porcelain boat, heat the porcelain boat to 550°C at a heating rate of 5°C per minute under N2 atmosphere, maintain for 3 hours, and then naturally cool to room temperature. After washing, S-modulated red carbon nitride is obtained, and the room temperature is the temperature in the range of 20-30°C.
[0030] S3. Weigh 1.0 g of S-modified red carbon nitride and 1% Cu atomic mass ratio of CuCl (15.6 mg of CuCl solid) and disperse them in 80 ml of ultrapure water, stir for 18 hours, and evaporate to dryness in a water bath at 90° C. to obtain the product;
[0031] S4. The product obtained in S3 is filtered and washed with ultrapure water until the ionic strength of the filtered solution is less than 20 ppm. The product is then placed in a vacuum drying oven and maintained at 60° C. for 12 hours to obtain a S-modulated 1% Cu single-atom doped red carbon nitride sample.
[0032] Example 2
[0033] A method for synthesizing S-modulated Cu single-atom-supported red carbon nitride comprises the following steps:
[0034] S1. Weigh 1.0 g of melamine, 0.3 g of 2,4,6-triaminopyrimidine, 1.0 g of thiocyanate, and 2.0 g of potassium chloride in a mortar and grind thoroughly for 10 minutes.
[0035] S2. Place the mixed and ground powder in a porcelain boat, heat the porcelain boat to 550°C at a heating rate of 5°C per minute under N2 atmosphere, maintain for 3 hours, and then naturally cool to room temperature. After washing, S-modulated red carbon nitride is obtained, and the room temperature is the temperature in the range of 20-30°C.
[0036] S3. Weigh 1.0 g of S-modified red carbon nitride and 0.5% Cu atomic mass ratio of CuCl (7.8 mg of CuCl solid) and disperse them in 80 ml of ultrapure water, stir for 18 hours, and evaporate to dryness in a water bath at 95°C to obtain the product;
[0037] S4. The product obtained in S3 is filtered and washed with ultrapure water until the ionic strength of the filtered solution is less than 20 ppm. The product is then placed in a vacuum drying oven at 60° C. for 12 hours to obtain a S-modulated 0.5% Cu single-atom-loaded red carbon nitride sample.
[0038] Example 3
[0039] A method for synthesizing S-modulated Cu single-atom-supported red carbon nitride comprises the following steps:
[0040] S1. Weigh 1.0 g of melamine, 0.3 g of 2,4,6-triaminopyrimidine, 1.0 g of thiocyanate, and 2.0 g of potassium chloride in a mortar and grind thoroughly for 10 minutes.
[0041] S2. Place the mixed and ground powder in a porcelain boat, heat the porcelain boat to 550°C at a heating rate of 5°C per minute under N2 atmosphere, maintain for 3 hours, and then naturally cool to room temperature. After washing, S-modulated red carbon nitride is obtained, and the room temperature is the temperature in the range of 20-30°C.
[0042] S3. Weigh 1.0 g of S-modified red carbon nitride and 3% Cu atomic mass ratio of CuCl (46.8 mg of CuCl solid) and disperse them in 80 ml of ultrapure water. Stir for 18 hours and evaporate to dryness in a water bath at 100° C. to obtain the product.
[0043] S4. The product obtained in S3 is filtered and washed with ultrapure water until the ionic strength of the filtered solution is less than 20 ppm. The product is then placed in a vacuum drying oven and maintained at 60° C. for 12 hours to obtain a S-modulated 3% Cu single-atom-loaded red carbon nitride sample.
[0044] Comparative Example
[0045] Melamine, 2,4,6-triaminopyrimidine, trithiocyanate and potassium chloride are fully ground and calcined in one step to obtain a product, and the obtained product is washed with water and dried to obtain S-modulated red carbon nitride.
[0046] The performance of the red carbon nitride prepared in Example 1 was tested below.
[0047] The product of Example 1 was characterized by high-precision morphology using a high-angle annular dark field scanning transmission electron microscope with spherical aberration correction. The red carbon nitride obtained in Example 1 is a Cu single-atom supported system modulated by S, as shown in the attached figure. Figure 1 shown.
[0048] The product obtained in Example 1 and the S-modulated red carbon nitride were characterized by X-ray photoelectron spectroscopy. The high-magnification X-ray photoelectron spectroscopy of Cu element showed that the product obtained in Example 1 contained Cu single atoms, as shown in the attached figure. Figure 2 shown.
[0049] The CO2 adsorption capacity of the product obtained in Example 1 and the red carbon nitride modulated by S was analyzed by CO2 adsorption. Figure 3 As shown, the product obtained in Example 1 has higher CO2 adsorption performance. CO2 adsorption is a prerequisite for CO2 reduction. Higher CO2 adsorption performance is conducive to the photocatalytic CO2 reduction reaction.
[0050] The photocatalytic performance of the samples was evaluated by photocatalytic CO2 reduction in a CO2 gas-filled reactor filled with water. The reactor was made of quartz glass and a xenon lamp (0.5 W / cm -2 Before the photocatalytic experiment begins, 10 mg of the catalyst is dispersed in 10 ml of ultrapure water in a reactor. The reactor containing the mixture is then placed on a magnetic stirrer. In the absence of light, the mixture is stirred evenly with the magnetic stirrer until it reaches adsorption / desorption equilibrium with CO2. After 30 minutes, the xenon lamp is turned on and the test begins. After five hours of illumination, the gas phase products are analyzed using a gas chromatograph, and the liquid phase products are analyzed using a nuclear magnetic resonance spectrometer.
[0051] The reduction performance of the product obtained in Example 1 and the red carbon nitride modulated by S to CO2 under simulated sunlight is shown in the attached Figure 4 The yields of various products are shown in the figure, from which it can be seen that the products prepared by the present invention have good photocatalytic effect.
[0052] like Figure 5 As shown, the ethanol production in Example 1 reached 50.43 μmol / g / h, the ethanol production in Example 2 was 16.08 μmol / g / h, and the ethanol production in Example 3 was 7.76 μmol / g / h.
Claims
1. A method for synthesizing S-modulated Cu single-atom-supported red carbon nitride, characterized in that: The steps include: S1. Mix melamine, 2,4,6-triaminopyrimidine, thiocyanate and potassium chloride in a mortar and grind them thoroughly according to the proportions; S2, placing the mixed and ground powder in a porcelain boat, heating it to the calcination temperature in a N2 atmosphere, calcining it for a period of time and then cooling it to room temperature, and washing it to obtain S-modulated red carbon nitride; S3, based on the mass of the red carbon nitride sample modulated by S, the mass of the added CuCl solid is calculated according to the mass percentage of the added Cu single atom, and the red carbon nitride modulated by S and the CuCl solid are mixed and stirred in ultrapure water for a period of time and then evaporated to dryness to obtain a product; The evaporated product is washed and vacuum dried to obtain a S-modulated Cu single-atom-loaded red carbon nitride sample.
2. The synthesis method according to claim 1, characterized in that In step S1, the mass ratio of melamine, 2,4,6-triaminopyrimidine, thiocyanate and potassium chloride is 10:3:10:20, and the grinding time is 5-20 minutes.
3. The synthesis method according to claim 1, characterized in that In step S2, the calcination temperature is 500-600°C, the calcination time is 2-4 hours, the heating rate is 4-6°C / min; and the calcination is cooled to room temperature by natural cooling under N2 atmosphere.
4. The synthesis method according to claim 1, characterized in that In step S3, the amount of CuCl solid added is: the mass of Cu single atom is 0.5-3% of the mass of S-modulated red carbon nitride.
5. The synthesis method according to claim 1, characterized in that In step S3, the stirring time is 10-20 hours; and the evaporation temperature is 80-100°C.
6. The synthesis method according to claim 1, characterized in that In step S3, the cleaning method is: the product is filtered and washed with ultrapure water until the ion concentration is less than 20 ppm.
7. The synthesis method according to claim 1, characterized in that In step S3, the vacuum drying temperature is 50-70°C and the drying time is 10-15h.
8. Use of the S-modulated Cu single-atom-supported red carbon nitride prepared by the synthesis method according to any one of claims 1 to 7 for reducing CO2 under simulated sunlight.