A photocatalytic composite material, a preparation method thereof and application thereof in reduction of carbon dioxide
By using g-C3N4 composite materials modified with amino-functionalized ionic liquids and metal oxides, the problem of insufficient carbon dioxide capture capacity of photocatalysts was solved, and the efficient conversion of carbon dioxide into methanol was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEBEI WEIWO ENVIRONMENT ENG TECH CO LTD
- Filing Date
- 2023-10-27
- Publication Date
- 2026-05-15
AI Technical Summary
In existing photocatalytic conversion methods, photocatalysts have poor ability to capture carbon dioxide and low catalytic efficiency, which limits the conversion rate of carbon dioxide.
The g-C3N4 composite material, co-modified with amino-functionalized ionic liquid and metal oxide, introduces new catalytic sites through hydrogen bond-induced binding, thereby improving charge separation efficiency and carbon dioxide capture capacity, and reducing overpotential during the reduction process.
The catalytic composite material significantly improves the reduction efficiency of carbon dioxide, and can efficiently convert carbon dioxide into methanol with a TOF value of up to 14.56 h⁻¹, thus achieving efficient carbon dioxide conversion.
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalytic materials, and specifically discloses a photocatalytic composite material, its preparation method, and its application in the reduction of carbon dioxide. Background Technology
[0002] With the rapid development of society and the economy, the demand for energy is increasing daily. However, this massive energy consumption also leads to the generation of increasing amounts of carbon dioxide and other harmful gases, posing a significant threat to the long-term survival and development of humankind. Currently, strategies for reducing carbon dioxide emissions mainly include carbon dioxide capture and storage (CCS) and carbon dioxide conversion and utilization. However, CCS suffers from poor economic viability and a high risk of leakage. Therefore, carbon dioxide conversion has become the primary solution for reducing carbon dioxide emissions.
[0003] Carbon dioxide conversion mainly includes chemical conversion and biological conversion. However, with declining vegetation, biological conversion of carbon dioxide has become increasingly complex and costly. Therefore, chemical conversion has become the primary means of alleviating the pressure of carbon dioxide treatment. Chemical conversion methods are further divided into electrochemical conversion, photocatalytic conversion, thermocatalytic conversion, and biochemical catalytic conversion. Among these, photocatalytic conversion has gained increasing attention due to its advantages of low energy consumption and environmental friendliness. However, the catalytic capacity of photocatalytic materials used in photocatalytic conversion is limited, and the ability of photocatalysts to capture carbon dioxide is poor, resulting in less than ideal carbon dioxide conversion rates. Therefore, developing a catalytic material with high carbon dioxide conversion efficiency and a simple structure is of great significance for reducing carbon dioxide emissions. Summary of the Invention
[0004] To address the problems of low catalytic efficiency and ineffective carbon dioxide capture in existing photocatalytic conversion methods for carbon dioxide treatment, this invention provides a photocatalytic composite material, its preparation method, and its application in carbon dioxide reduction. This invention utilizes g-C3N4 co-modified with amino-functionalized ionic liquid and metal oxide as a photocatalyst to catalyze the reduction of carbon dioxide to methanol.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution.
[0006] The first aspect of the present invention provides a photocatalytic composite material, wherein the photocatalytic composite material is a g-C3N4 composite material co-modified with an amino-functionalized ionic liquid and a metal oxide.
[0007] Compared to existing technologies, this invention provides a photocatalytic composite material, wherein the photocatalytic material is a g-C3N4 composite material co-modified with an amino-functionalized ionic liquid and a metal oxide. Because g-C3N4 is non-toxic, harmless, has a wide range of raw material sources, and exhibits visible light responsiveness, it has a very broad application prospect in the field of photocatalysis. However, g-C3N4 has poor charge separation performance; when the charge is excited, electron-hole recombination easily occurs, limiting the charge separation efficiency of g-C3N4. Furthermore, g-C3N4 has relatively few surface catalytic sites, resulting in poor photocatalytic activity.
[0008] Based on this, this invention utilizes hydrogen bonding to induce the binding of an amino-functionalized ionic liquid with g-C3N4, effectively introducing new catalytic sites and enhancing the photocatalytic activity of g-C3N4. Furthermore, due to the unique cavity structure of g-C3N4, metals are more easily anchored to its surface. This invention introduces metal oxides onto the g-C3N4 surface, and through charge transfer from g-C3N4, the metal oxide surface becomes electron-rich, improving the charge separation efficiency of g-C3N4. Combined with the catalytic sites formed by the ionic liquid, this facilitates the reduction of carbon dioxide. Moreover, the amino-functionalized ionic liquid contains -NH2, which has a high affinity for carbon dioxide, enabling efficient capture of carbon dioxide while simultaneously reducing the overpotential during carbon dioxide reduction, thus promoting carbon dioxide reduction.
[0009] Preferably, the amino-functionalized ionic liquid is an amino-functionalized imidazole ionic liquid.
[0010] Preferably, the metal oxide is a transition metal oxide.
[0011] More preferably, the amino-functionalized ionic liquid is any one of 1-aminoethyl-2,3-dimethylimidazolium aminoethanesulfonate or 1-(2-aminoethyl)-3-methylimidazolium hexafluorophosphate.
[0012] The 1-(2-aminoethyl)-3-methylimidazolium hexafluorophosphate can be obtained according to the synthesis method described in the literature (Song G, Cai Y, Peng Y. Amino-Functionalized Ionic Liquid as A Nucleophilic Scavenger in SolutionPhase Combinatorial Synthesis[J]. Journal of Combinatorial Chemistry, 2005, 7(4): 561-566.).
[0013] More preferably, the metal oxide is any one of zinc oxide, titanium dioxide, or tungsten trioxide.
[0014] A second aspect of the present invention provides a method for preparing the aforementioned photocatalytic composite material, comprising the following steps:
[0015] Step 1: Disperse the nitrogen source in deionized water, adjust the pH to 4-5, and dry to obtain acidified nitrogen source powder;
[0016] Step 2: Under an inert atmosphere, heat the acidified nitrogen source powder to 550℃-580℃, keep it at that temperature for 2h-3h, and then cool it to room temperature to obtain g-C3N4 powder.
[0017] Step 3: Disperse the g-C3N4 powder in an alcohol solution and sonicate to obtain a g-C3N4 dispersion;
[0018] Step 4: Mix the g-C3N4 dispersion with a transition metal salt solution and carry out a hydrothermal reaction at 250℃-350℃. After the reaction is complete, wash and dry to obtain the photocatalytic composite material precursor.
[0019] Step 5: Disperse the photocatalytic composite material precursor in a mixed solution containing amino-functionalized ionic liquid, react under an inert atmosphere for 4-6 hours, and dry to obtain the photocatalytic composite material.
[0020] Preferably, in step one, the nitrogen source is any one or two of urea, melamine, or cyanuric acid.
[0021] Preferably, in step one, the mass-to-volume ratio of the nitrogen source to the deionized water is 1g:2mL-2.5mL.
[0022] Preferably, in step one, the drying temperature is 70℃-90℃ and the drying time is 8h-12h.
[0023] Preferably, in step two, the temperature rise is achieved using a programmed temperature rise method, and the temperature rise rate of the programmed temperature rise method is 6℃ / min-8℃ / min.
[0024] Preferably, in step three, the mass-to-volume ratio of the g-C3N4 powder to the alcohol solution is 1g:20mL-30mL.
[0025] Preferably, in step three, the alcohol solution is an ethanol solution with a mass concentration of 70%-80%.
[0026] Preferably, in step three, the frequency of the ultrasonic treatment is 35kHz-40kHz, and the duration of the ultrasonic treatment is 10min-20min.
[0027] Preferably, in step four, the volume ratio of the g-C3N4 dispersion to the transition metal salt solution with a concentration of 0.05 mol / L-0.1 mol / L is 1:0.01-0.05.
[0028] Preferably, in step four, the transition metal salt solution is any one of copper chloride solution, copper nitrate solution, zinc nitrate solution, zinc chloride solution, or titanium tetrachloride solution.
[0029] Preferably, in step four, the hydrothermal reaction takes 1-3 hours.
[0030] Preferably, in step four, the washing involves washing with deionized water 2-3 times, followed by washing with anhydrous ethanol 1-3 times.
[0031] Preferably, in step four, the drying temperature is 60℃-100℃, and the drying time is 4h-8h.
[0032] Preferably, in step five, the mixed solution containing amino-functionalized ionic liquid includes amino-functionalized ionic liquid and methanol solution, wherein the mass-volume ratio of amino-functionalized ionic liquid to methanol solution is 1g:10mL-20mL.
[0033] Preferably, the mass-to-volume ratio of the photocatalytic composite material precursor to the mixed solution of the amino-functionalized ionic liquid is 1g:20mL-30mL.
[0034] Preferably, in step five, the reaction temperature is 85℃-100℃.
[0035] Preferably, in step five, the drying temperature is 50℃-70℃, and the drying time is 6h-10h.
[0036] A third aspect of the present invention provides the application of the aforementioned photocatalytic composite material or the photocatalytic composite material prepared by the method described above in the reduction of carbon dioxide.
[0037] In summary, this invention provides a photocatalytic composite material and its preparation method. The photocatalytic composite material uses g-C3N4 co-modified with an amino-functionalized ionic liquid and a metal oxide. The amino-functionalized ionic liquid combined with the metal oxide modifies g-C3N4, introducing catalytic sites and improving its charge separation efficiency, thus effectively enhancing the photocatalytic composite material's ability to reduce carbon dioxide. This invention effectively solves the problem of low conversion efficiency of photocatalysts in the photocatalytic conversion method for treating carbon dioxide in existing technologies. Using the photocatalytic composite material provided by this invention, carbon dioxide can be efficiently reduced to methanol. Tests show that the TOF value of the photocatalytic composite material can reach 14.56 h⁻¹. -1 . Detailed Implementation
[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.
[0039] Example 1
[0040] This embodiment provides a photocatalytic composite material, which specifically includes the following steps:
[0041] Step 1: Disperse 5g of urea in 10mL of deionized water, heat to 60℃, stir to dissolve, adjust pH to 4.5, and dry at 80℃ for 10h to obtain acidified nitrogen source powder.
[0042] Step 2: Under an inert atmosphere, the acidified nitrogen source powder is heated to 560°C at a heating rate of 7°C / min, held at that temperature for 3 hours, and then cooled to room temperature to obtain g-C3N4 powder.
[0043] Step 3: Disperse the 5g g-C3N4 powder in 100mL of 70% ethanol solution and sonicate at 35kHz for 20min to obtain g-C3N4 dispersion.
[0044] Step 4: Mix the g-C3N4 dispersion with 3 mL of 0.08 mol / L zinc chloride solution, transfer it to a high-pressure reactor lined with polytetrafluoroethylene, and carry out a hydrothermal reaction at 300°C for 3 h. After the reaction is complete, wash with deionized water 3 times and anhydrous ethanol 2 times, and dry at 80°C for 6 h to obtain the photocatalytic composite material precursor.
[0045] Step 5: Disperse the 5g photocatalytic composite material precursor in 100mL of methanol solution containing 8g of 1-aminoethyl-2,3-dimethylimidazolium aminoethanesulfonate, react at 90℃ for 5h in an inert atmosphere, filter, wash the solid filter material three times with deionized water and once with anhydrous ethanol, and dry at 60℃ for 8h to obtain the photocatalytic composite material.
[0046] Example 2
[0047] This embodiment provides a photocatalytic composite material, which specifically includes the following steps:
[0048] Step 1: Disperse 5g of melamine in 10mL of deionized water, heat to 60℃, stir to dissolve, adjust pH to 4.9, and dry at 70℃ for 10h to obtain acidified nitrogen source powder;
[0049] Step 2: Under an inert atmosphere, the acidified nitrogen source powder is heated to 550°C at a heating rate of 6°C / min, held at that temperature for 3 hours, and then cooled to room temperature to obtain g-C3N4 powder.
[0050] Step 3: Disperse the 5g g-C3N4 powder in 100mL of 75% ethanol solution and sonicate at 35kHz for 15min to obtain g-C3N4 dispersion.
[0051] Step 4: Mix the g-C3N4 dispersion with 3 mL of 0.1 mol / L titanium tetrachloride solution, transfer it to a high-pressure reactor lined with polytetrafluoroethylene, and carry out a hydrothermal reaction at 350 °C for 1.5 h. After the reaction is completed, wash with deionized water 3 times and anhydrous ethanol 2 times, and dry at 75 °C for 8 h to obtain the photocatalytic composite material precursor.
[0052] Step 5: Disperse the 5g photocatalytic composite material precursor in 80mL of methanol solution containing 8g of 1-(2-aminoethyl)-3-methylimidazolium hexafluorophosphate, react at 85°C for 6h in an inert atmosphere, filter, wash the solid filter material three times with deionized water and once with anhydrous ethanol, and dry at 70°C for 6h to obtain the photocatalytic composite material.
[0053] Example 3
[0054] This embodiment provides a photocatalytic composite material, which specifically includes the following steps:
[0055] Step 1: Disperse 5g of urea in 10mL of deionized water, heat to 60℃, stir to dissolve, adjust pH to 4.1, and dry at 90℃ for 12h to obtain acidified nitrogen source powder.
[0056] Step 2: Under an inert atmosphere, the acidified nitrogen source powder is heated to 580°C at a heating rate of 8°C / min, held at that temperature for 3 hours, and then cooled to room temperature to obtain g-C3N4 powder.
[0057] Step 3: Disperse the 5g g-C3N4 powder in 100mL of 70% ethanol solution and sonicate at a frequency of 40kHz for 10min to obtain g-C3N4 dispersion.
[0058] Step 4: Mix the g-C3N4 dispersion with 3 mL of 0.05 mol / L ammonium tungstate solution, transfer the mixture to a high-pressure reactor lined with polytetrafluoroethylene, and carry out a hydrothermal reaction at 260°C for 3 h. After the reaction is complete, wash the mixture 3 times with deionized water and 2 times with anhydrous ethanol, and dry it at 80°C for 6 h to obtain the photocatalytic composite material precursor.
[0059] Step 5: Disperse the 5g photocatalytic composite material precursor in 100mL of methanol solution containing 8g 1-aminoethyl-2,3-dimethylimidazolium aminoethanesulfonate, react at 100℃ for 4h in an inert atmosphere, filter, wash the solid filter material three times with deionized water and once with anhydrous ethanol, and dry at 60℃ for 8h to obtain the photocatalytic composite material.
[0060] Comparative Example 1
[0061] This comparative example provides a photocatalytic composite material, which differs from Example 1 in that the photocatalytic composite material is a zinc oxide-modified g-C3N4 material, specifically including the following steps:
[0062] Step 1: Disperse 5g of urea in 10mL of deionized water, heat to 60℃, stir to dissolve, adjust pH to 4.5, and dry at 80℃ for 10h to obtain acidified nitrogen source powder.
[0063] Step 2: Under an inert atmosphere, the acidified nitrogen source powder is heated to 560°C at a heating rate of 7°C / min, held at that temperature for 3 hours, and then cooled to room temperature to obtain g-C3N4 powder.
[0064] Step 3: Disperse the 5g g-C3N4 powder in 100mL of 70% ethanol solution and sonicate at 35kHz for 20min to obtain g-C3N4 dispersion.
[0065] Step 4: Mix the g-C3N4 dispersion with 3 mL of 0.08 mol / L zinc chloride solution, transfer the mixture to a high-pressure reactor lined with polytetrafluoroethylene, and carry out a hydrothermal reaction at 300°C for 3 h. After the reaction is complete, wash the mixture 3 times with deionized water and 2 times with anhydrous ethanol, and dry it at 80°C for 6 h to obtain the photocatalytic composite material.
[0066] Comparative Example 2
[0067] This comparative example provides a photocatalytic composite material, which differs from Example 1 in that the photocatalytic composite material is a g-C3N4 material modified with an amino-functionalized ionic liquid, and specifically includes the following steps:
[0068] Step 1: Disperse 5g of urea in 10mL of deionized water, heat to 60℃, stir to dissolve, adjust pH to 4.5, and dry at 80℃ for 10h to obtain acidified nitrogen source powder.
[0069] Step 2: Under an inert atmosphere, the acidified nitrogen source powder is heated to 560°C at a heating rate of 7°C / min, held at that temperature for 3 hours, and then cooled to room temperature to obtain g-C3N4 powder.
[0070] Step 3: Disperse the 5g g-C3N4 powder in 100mL of 70% ethanol solution and sonicate at 35kHz for 20min to obtain g-C3N4 dispersion.
[0071] Step 4: Disperse the 5g g-C3N4 dispersion in 100mL of methanol solution containing 8g 1-aminoethyl-2,3-dimethylimidazolium aminoethanesulfonate, react at 90℃ for 5h in an inert atmosphere, filter, wash the solid filter material three times with deionized water and once with anhydrous ethanol, and dry at 60℃ for 8h to obtain the photocatalytic composite material.
[0072] Comparative Example 3
[0073] This comparative example provides a photocatalytic composite material, which differs from Example 1 in that the ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate, and specifically includes the following steps:
[0074] Step 1: Disperse 5g of urea in 10mL of deionized water, heat to 60℃, stir to dissolve, adjust pH to 4.5, and dry at 80℃ for 10h to obtain acidified nitrogen source powder.
[0075] Step 2: Under an inert atmosphere, the acidified nitrogen source powder is heated to 560°C at a heating rate of 7°C / min, held at that temperature for 3 hours, and then cooled to room temperature to obtain g-C3N4 powder.
[0076] Step 3: Disperse the 5g g-C3N4 powder in 100mL of 70% ethanol solution and sonicate at 35kHz for 20min to obtain g-C3N4 dispersion.
[0077] Step 4: Mix the g-C3N4 dispersion with 3 mL of 0.08 mol / L zinc chloride solution, transfer it to a high-pressure reactor lined with polytetrafluoroethylene, and carry out a hydrothermal reaction at 300°C for 3 h. After the reaction is complete, wash with deionized water 3 times and anhydrous ethanol 2 times, and dry at 80°C for 6 h to obtain the photocatalytic composite material precursor.
[0078] Step 5: Disperse the 5g photocatalytic composite material precursor in 100mL of methanol solution containing 8g of 1-butyl-3-methylimidazolium hexafluorophosphate, react at 90℃ for 5h in an inert atmosphere, filter, wash the solid filter material three times with deionized water and once with anhydrous ethanol, and dry at 60℃ for 8h to obtain the photocatalytic composite material.
[0079] To further verify the technical effect of the present invention, the photocatalytic composite materials obtained in Examples 1-3 and Comparative Examples 1-2 were subjected to carbon dioxide reduction catalysis tests. The specific operation is as shown in Experiment 1, and the specific test results are shown in Table 1.
[0080] Experimental Example 1
[0081] 0.1 g of the photocatalytic composite material was dispersed in 100 mL of ultrapure water and placed into a sealed reactor with a gas inlet and outlet. The gas inlet and outlet were opened, and high-purity CO2 gas was introduced into the reactor for 20 min to remove oxygen from the water and air from the reactor. Finally, CO2 gas was introduced until the pressure inside the reactor reached 0.8 MPa and maintained for 30 min to allow the catalyst and CO2 to reach adsorption-desorption equilibrium. The reaction temperature was set to 60 °C, and a xenon lamp (wavelength ≥ 420 nm) was used as a simulated visible light source to conduct the photocatalytic reaction. The concentration of methanol in the product was detected using high-performance liquid chromatography (HPLC), and the methanol yield and the time-of-flight (TOF) value were calculated (calculation formula: TOF = methanol concentration / (catalyst concentration × reaction time)).
[0082] Table 1. Results of CO2 reduction by photocatalytic composite materials obtained in Examples 1-3 and Comparative Examples 1-2
[0083] project Methanol yield / μmol <![CDATA[TOF(h -1 )]]> Example 1 728 14.56 Example 2 706 14.12 Example 3 692 13.84 Comparative Example 1 467 9.34 Comparative Example 2 414 8.28 Comparative Example 3 458 9.16
[0084] As shown in Table 1, the photocatalytic composite materials provided in Examples 1-3 of this invention can catalyze the conversion of carbon dioxide into methanol, and exhibit high catalytic activity, with a maximum TOF value of 14.56 h. -1 The yield of methanol obtained can reach 728 μmol, which also confirms that the photocatalytic composite material provided by the present invention has excellent catalytic performance.
[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A photocatalytic composite material, characterized in that: The photocatalytic composite material is a g-C3N4 composite material co-modified with an amino-functionalized ionic liquid and a metal oxide; the amino-functionalized ionic liquid is any one of 1-aminoethyl-2,3-dimethylimidazolium aminoethanesulfonate or 1-(2-aminoethyl)-3-methylimidazolium hexafluorophosphate. The metal oxide is any one of zinc oxide, titanium dioxide, or tungsten trioxide.
2. A method for preparing the photocatalytic composite material as described in claim 1, characterized in that: Includes the following steps: Step 1: Disperse the nitrogen source in deionized water, adjust the pH to 4-5, and dry to obtain acidified nitrogen source powder; Step 2: Under an inert atmosphere, heat the acidified nitrogen source powder to 550℃-580℃, keep it at that temperature for 2h-3h, and then cool it to room temperature to obtain g-C3N4 powder. Step 3: Disperse the g-C3N4 powder in an alcohol solution and sonicate to obtain a g-C3N4 dispersion; Step 4: Mix the g-C3N4 dispersion with a transition metal salt solution and carry out a hydrothermal reaction at 250℃-350℃. After the reaction is complete, wash and dry to obtain the photocatalytic composite material precursor. Step 5: Disperse the photocatalytic composite material precursor in a mixed solution containing amino-functionalized ionic liquid, react under an inert atmosphere for 4-6 hours, and dry to obtain the photocatalytic composite material.
3. The method for preparing the photocatalytic composite material as described in claim 2, characterized in that: In step one, the nitrogen source is any one or two of urea, melamine, or cyanuric acid; and / or In step one, the mass-to-volume ratio of the nitrogen source to deionized water is 1g:2mL-2.5mL.
4. The method for preparing the photocatalytic composite material as described in claim 2, characterized in that: In step two, the temperature rise is achieved using a programmed temperature rise method, with a temperature rise rate of 6℃ / min-8℃ / min; and / or In step three, the mass-to-volume ratio of the g-C3N4 powder to the alcohol solution is 1g:20mL-30mL; and / or In step three, the alcohol solution is an ethanol solution with a mass concentration of 70%-75%.
5. The method for preparing the photocatalytic composite material as described in claim 2, characterized in that: In step four, the volume ratio of the g-C3N4 dispersion to the transition metal salt solution with a concentration of 0.05 mol / L-0.1 mol / L is 1:0.01-0.05; and / or In step four, the transition metal salt solution is any one of zinc nitrate solution, zinc chloride solution, titanium tetrachloride solution, or ammonium tungstate solution.
6. The method for preparing the photocatalytic composite material as described in claim 2, characterized in that: In step four, the hydrothermal reaction takes 1-3 hours.
7. The method for preparing the photocatalytic composite material as described in claim 2, characterized in that: In step five, the mixed solution containing amino-functionalized ionic liquid comprises amino-functionalized ionic liquid and methanol solution, wherein the mass-to-volume ratio of amino-functionalized ionic liquid to methanol solution is 1g:10mL-20mL; and / or In step five, the mass-to-volume ratio of the photocatalytic composite material precursor to the mixed solution of the amino-functionalized ionic liquid is 1 g: 20 mL-30 mL; and / or In step five, the reaction temperature is 85℃-100℃.
8. The application of a photocatalytic composite material as described in claim 1 or a photocatalytic composite material prepared by the preparation method of the photocatalytic composite material according to any one of claims 2-7 in the reduction of carbon dioxide.