Polyfluoroalkyl chain modified cobalt phthalocyanine molecule-carbon nanomaterial molecule electrocatalyst and preparation method thereof, and preparation method of CoPc / CNT electrode
By combining cobalt phthalocyanine molecules modified with polyfluoroalkyl chains with carbon nanomaterials, the problems of complex structure and precious metal limitations of existing electrocatalysts are solved, and efficient and stable electrocatalysis of CO2RR to CO is achieved, which is suitable for large-scale applications.
Patent Information
- Application Number
- CN202510599300.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-10
- Publication Date
- 2025-09-16
AI Technical Summary
Existing electrocatalysts in CO2RR have complex preparation processes and diverse catalytic center structures, making it difficult to improve electrocatalytic performance. In addition, precious metal catalysts are expensive, have low stability and selectivity, and molecular catalyst aggregation leads to poor conductivity, affecting catalytic performance.
By combining cobalt phthalocyanine molecules modified with polyfluoroalkyl chains with carbon nanomaterials, single-atom electrocatalysts with well-defined structures were prepared through π-π conjugation and physical adsorption. They were then applied to CoPc/CNT electrodes to achieve atomic-level dispersion of active metal sites and improved hydrophobicity.
The single selectivity of CO2RR to CO is achieved at low overpotential, while maintaining the Faradaic efficiency at high current density, providing efficient and stable electrocatalytic materials and laying the foundation for large-scale production.
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Figure CN120649082A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of electrocatalysis, and specifically relates to a polyfluoroalkyl chain-modified cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst and a preparation method thereof, and a preparation method of a CoPc / CNT electrode. Background Art
[0002] As the global energy crisis becomes increasingly pressing, the development of sustainable and environmentally friendly new energy technologies has become a top priority. Electrocatalytic carbon dioxide reduction (CO₂RR) to carbon monoxide (CO) and other chemicals and fuels can achieve the sequestration of CO₂, potentially mitigating global warming while producing commercially valuable products. This technology holds great promise.
[0003] However, single-atom electrocatalysts, currently a hot topic of research, exhibit excellent activity and selectivity in CO₂RR. However, their complex preparation processes and diverse catalytic center structures make it difficult to understand the structure-performance relationship and further improve their electrocatalytic performance. In contrast, molecular complex catalysts with well-defined structures are limited by molecular aggregation and poor conductivity, and their electrocatalytic performance and stability need to be improved. Using electricity generated from renewable energy to drive the electrochemical conversion of CO₂ can make it a high-value-added industrial raw material. Electrocatalytic CO₂RR is a potential pathway for the sustainable production of chemicals and fuels. In the field of electrocatalytic CO₂RR, efficient electrocatalysts are a key factor restricting the CO₂RR process. Simultaneously achieving CO₂RR at low overpotential while suppressing the competing reaction of hydrogen evolution is crucial for the development of efficient electrocatalysts. Although metal catalysts such as gold and silver currently exhibit good activity and selectivity in the electrocatalytic conversion of CO₂RR to CO, their price and availability restrict their large-scale application. Although metals such as indium, tin, and bismuth are a type of electrocatalytic material that can produce formic acid, and copper-based catalysts have obvious effects in converting CO2 into C1-C3 products such as methane, ethane, ethylene, ethanol, and propane, their main problems are low stability and selectivity.
[0004] Since the concept of single-molecule catalysis was proposed, the development of efficient single-atom electrocatalysts has become a hot topic in the field of electrocatalysis. Cobalt phthalocyanine is a single-atom catalyst that possesses these advantages. Among them, single-atom electrocatalysts with a metal-nitrogen-carbon structure have demonstrated high electrocatalytic activity, selectivity, and stability in the CO₂RR conversion to CO. Single-atom catalysts are among the most promising catalysts for CO₂ electrocatalytic reduction. However, the currently used preparation process of pyrolyzed metal salts and nitrogen-containing organic compounds inevitably leads to complex structures and diverse catalytic center structures, which poses a serious obstacle to understanding the structure-performance relationship of catalysts and further improving their electrocatalytic performance. Therefore, it is of great significance to construct single-molecule electrocatalysts with well-defined structures and to apply them to glassy carbon electrodes with commercial potential. Molecular complexes with metal-nitrogen coordination (such as metal phthalocyanines and metalloporphyrins) have attracted attention due to their well-defined structures. However, for most homogeneous molecular catalysts, their catalytic performance is often limited by molecular aggregation and poor conductivity, resulting in low catalytic reduction current density and difficulty in further improving their stability and selectivity. Summary of the Invention
[0005] In view of the deficiencies in the prior art, the present invention provides a polyfluoroalkyl chain-modified cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst and a preparation method thereof, as well as a preparation method of a CoPc / CNT electrode.
[0006] The technical solutions of the present invention are as follows:
[0007] A polyfluoroalkyl chain-modified cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst, characterized in that the cobalt phthalocyanine molecule has a structure shown in the following formula:
[0008]
[0009] The cobalt phthalocyanine molecules are modified by polyfluoroalkyl chains and are combined with carbon nanotubes through π-π conjugation and / or physical adsorption.
[0010] Preferably, the preparation method specifically comprises the following steps:
[0011] (a) Appropriate amounts of 4-nitrophthalonitrile, imidazole, and potassium carbonate were weighed and placed in a Schlenk flask. N2 was purged three times to ensure an inert atmosphere in the reaction tube. DMF with a water content of ≤0.001% was then added, and the mixture was heated in an oil bath at 60°C for 24 h. After the reaction, the reaction solution was poured into deionized water to precipitate a light yellow solid. The precipitate was collected by filtration and rinsed with methanol until the filtrate was colorless. The precipitate was placed in a vacuum drying oven for 12 h and dried to obtain 4-imidazolylphthalonitrile, as shown in Formula (I):
[0012]
[0013] (b) The product of step a and cobalt acetate were placed in a Schlenk flask. After N2 was purged three times, n-pentanol was added as the reaction solvent, followed by the slow addition of DBU as a reaction catalyst, and the mixture was heated in an oil bath at 140°C for 48 hours. After the reaction, the mixture was cooled to room temperature and then filtered. The separated solid was washed with deionized water, acetone, and ethanol, respectively, until the filtrate was colorless. The precipitate was dried in a vacuum drying oven for 12 hours to obtain a phthalocyanine molecular precursor having a nitrogen-coordinated cobalt metal center, as shown in formula (II):
[0014]
[0015] (c) The product from step b and 1H,1H-tridecafluoro-1-iodoheptane were placed in a Schlenk flask, purged with N2 three times, and MeOH with a water content of ≤0.001% was added. The flask was heated in an oil bath at 80°C for 24 h. After the reaction was completed, the flask was naturally cooled to room temperature to precipitate blue crystals. The crystals were filtered and dissolved in a small amount of methanol. Subsequently, methyl tert-butyl ether was slowly added dropwise under ultrasound to gradually precipitate solids. After filtration and drying, a dark blue polyfluoroalkyl chain-modified cobalt phthalocyanine molecule was obtained, as shown in Formula (III):
[0016]
[0017] Preferably, in step (a), 2.60 g (15 mmol) of 4-nitrophthalonitrile, 1.22 g (18 mmol) of imidazole, and 10.36 g (75 mmol) of potassium carbonate are weighed, and DMF (50 mL) having a moisture content of ≤0.001% is added; in step (b), 227.5 mg (0.5 mmol) of the product of step a, 132.7 mg (0.75 mmol) of cobalt acetate, and 1 mL of DBU are added, and n-pentanol (5 mL) having a moisture content of ≤0.001% is added; in step (c), 167.0 mg (0.2 mmol) of the product of step b, 1137.6 mg (2.4 mmol) of 1H,1H-tridecafluoro-1-iodoheptane are added, and methanol (8 mL) having a moisture content of ≤0.001% is added.
[0018] Preferably, the preparation method specifically comprises the following steps:
[0019] (d) An appropriate amount of multi-walled carbon nanotube powder was weighed and added to 100 mL of concentrated hydrochloric acid, sonicated for 1 h, then stirred for 12 h, filtered, washed with deionized water until neutral, and then centrifuged and freeze-dried;
[0020] (e) taking the product from step (d), adding 10 mL of DMF, and ultrasonicating for 30 min using an ultrasonic cleaner to obtain a uniformly dispersed carbon nanotube slurry;
[0021] (f) taking the polyfluoroalkyl chain-modified cobalt phthalocyanine molecular product described in step (c), adding 10 mL of DMF, and ultrasonicating using an ultrasonic cleaner for 30 minutes to obtain a uniformly dispersed cobalt phthalocyanine molecular slurry;
[0022] (g) taking equal volumes of the product of step (e) and step (f) and mixing them, stirring continuously for 20 to 30 hours to obtain a mixed solution g;
[0023] (h) The mixed solution g is collected by suction filtration, and the obtained filtrate is washed and dried to obtain a cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst.
[0024] Preferably, 0.5 g of multi-walled carbon nanotube powder is weighed in step (d), 30 mg of the product of step (d) is taken in step (e), and 0.3 to 3 mg of the polyfluoroalkyl chain-modified cobalt phthalocyanine molecular product of step (c) is taken in step (f).
[0025] Preferably, in step (f), 1.5 mg of the polyfluoroalkyl chain-modified cobalt phthalocyanine molecular product of step (c) is taken.
[0026] A method for preparing a CoPc / CNT electrode, characterized by comprising the following steps:
[0027] The prepared cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst was dispersed into a 1 mL mixed solution of Nafion, water and ethanol, and ultrasonicated for 30 min to obtain a uniform black catalyst slurry. The black catalyst slurry was dripped onto a surface area of 1 cm 2 On the carbon paper electrode, a working electrode film was formed by drying under moist room temperature conditions. The loading amount of CoPc / CNT was 0.1-1 mg cm -2 , forming a CoPc / CNT electrode.
[0028] Preferably, the volume ratio of Nafion, water and ethanol is 2:49:49.
[0029] Preferably, the loading of CoPc / CNT is 0.5 mg cm -2 .
[0030] The present invention has the following technical effects:
[0031] (1) Polyfluoroalkyl chains-mediated Co active metal sites are atomically dispersed on the carbon nanotube surface and greatly promote charge transfer during electrolysis.
[0032] (2) The polyfluoroalkyl chain also gives the active site excellent hydrophobicity, stabilizes the gas-liquid-solid three-phase interface in the GDE catalyst layer, prevents the overflow of the electrode electrolyte and promotes the mass transfer process of CO2, thereby improving the catalytic activity, achieving the single selectivity of CO2RR to CO, and maintaining a Faradaic efficiency of more than 90% at high current density, which is suitable for large-scale production and application, and provides ideas for the design of high-performance CO2RR electrocatalytic materials with hydrophobicity. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 This is the ultraviolet spectrum of the cobalt phthalocyanine molecule prepared in Example 1.
[0034] Figure 2 This is a high-resolution mass spectrum of the cobalt phthalocyanine molecule prepared in Example 1.
[0035] Figure 3 This is a polarization curve diagram of the electrochemical reduction of CO2 to CO using the cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst prepared in Example 1.
[0036] Figure 4 This is a Faraday efficiency diagram of the electrochemical reduction of CO2 to CO using the cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst prepared in Example 1.
[0037] Figure 5 This is a partial current density curve of the electrochemical reduction of CO2 to CO using the cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst prepared in Example 1.
[0038] Figure 6 This is a graph of the conversion frequency (TOF) of the electrochemical reduction of CO2 to CO using the cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst prepared in Example 1. DETAILED DESCRIPTION
[0039] The present invention provides a polyfluoroalkyl chain-modified cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst, a preparation method thereof, and a preparation method of a CoPc / CNT electrode. To further clarify and define the objectives, technical solutions, and effects of the present invention, the following examples further illustrate the technical solutions of the present invention. It should be understood that the specific examples described herein are merely illustrative of the present invention and are not intended to limit the present invention.
[0040] The raw materials and reagents used in the present invention can all be obtained from commercial sources.
[0041] The following is a detailed description through specific embodiments.
[0042] A method for preparing a polyfluoroalkyl chain-modified cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst specifically comprises the following steps:
[0043] (a) 2.60 g (15 mmol) of 4-nitrophthalonitrile, 1.22 g (18 mmol) of imidazole, and 10.36 g (75 mmol) of potassium carbonate were weighed and placed in a 100 mL Schlenk flask. N2 was purged three times to ensure an inert atmosphere in the reaction tube. 50 mL of ultra-dry DMF (moisture content ≤ 0.001%) was then added and heated in an oil bath at 60°C for 24 h. After the reaction was completed, the reaction solution was poured into 500 mL of deionized water to precipitate a light yellow solid. The precipitate was collected by filtration and rinsed with methanol until the filtrate was colorless. The precipitate was placed in a vacuum drying oven for 12 h and dried to obtain 4-imidazolylphthalonitrile, as shown in Formula (I):
[0044]
[0045] (b) 227.5 mg (0.5 mmol) of the product from step (a) and 132.7 mg (0.75 mmol) of cobalt acetate were placed in a 25 mL Schlenk flask. After N2 was purged three times, 5 mL of n-pentanol was added as the reaction solvent, followed by the slow addition of 1 mL of DBU as a catalyst. The mixture was heated in an oil bath at 140°C for 48 h. After the reaction, the mixture was cooled to room temperature and filtered. The separated solid was washed with deionized water, acetone, and ethanol, respectively, until the filtrate was colorless. The precipitate was dried in a vacuum oven for 12 h to obtain a phthalocyanine precursor having a nitrogen-coordinated cobalt metal center, as shown in Formula (II):
[0046]
[0047] (c) 167.0 mg (0.2 mmol) of the product from step b and 1137.6 mg (2.4 mmol) of 1H,1H-tridecafluoro-1-iodoheptane were placed in a 25 mL Schlenk flask, purged with N2 three times, and 8 mL of ultra-dry methanol (water content ≤ 0.001%) was added. The mixture was heated in an 80°C oil bath for 24 h. After the reaction was completed, the mixture was cooled naturally to room temperature to precipitate blue crystals. The crystals were filtered and dissolved in a small amount of methanol. Subsequently, methyl tert-butyl ether was slowly added dropwise under ultrasound, and solids gradually precipitated. After filtration and drying, a dark blue polyfluoroalkyl chain-modified cobalt phthalocyanine molecule was obtained, as shown in Formula (III):
[0048]
[0049] (d) 0.5 g of multi-walled carbon nanotube powder was weighed and added to 100 mL of concentrated hydrochloric acid. The mixture was ultrasonicated for 1 h and then stirred overnight. The mixture was filtered, washed with deionized water until neutral, and then centrifuged and freeze-dried.
[0050] (e) 30 mg of the product from step (d) was added with 10 mL of DMF and ultrasonicated for 30 min to obtain a uniformly dispersed carbon nanotube slurry.
[0051] (f) 0.3-3 mg, preferably 1.5 mg, of the polyfluoroalkyl chain-modified cobalt phthalocyanine product described in step (c) was added to 10 mL of DMF and sonicated for 30 min using an ultrasonic cleaner to obtain a uniformly dispersed cobalt phthalocyanine slurry.
[0052] (g) Mix equal volumes of the product from step (f) and step (e), and continue stirring for 20 to 30 hours to obtain a mixed solution g.
[0053] (h) The mixed solution g is collected by suction filtration, and the obtained filtrate is washed and dried to obtain a cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst.
[0054] This embodiment provides a method for preparing a CoPc / CNT electrode, specifically:
[0055] 5 mg of the cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst prepared in Example 1 was dispersed into 1 mL of a mixed solution of Nafion, water, and ethanol, with a volume ratio of Nafion, water, and ethanol of 2:49:49. After ultrasonication for 30 min, a uniform black catalyst slurry was obtained. The black catalyst slurry was dripped onto a surface area of 1 cm 2 On the carbon paper electrode, a working electrode film was formed by drying under moist room temperature conditions. The loading amount of CoPc / CNT was 0.1-1 mg cm -2 , the best is 0.5mgcm -2 , forming a CoPc / CNT electrode.
[0056] The performance of the prepared CoPc / CNT molecular electrocatalyst for the electroreduction of CO2 to CO was tested using a three-electrode electrolytic cell. The CoPc / CNT electrode was the working electrode, the counter electrode was a platinum electrode, the reference electrode was an Ag / AgCl electrode, and the electrolyte was a 1.0 M potassium hydroxide solution. During the test, the carbon dioxide gas flow rate was maintained at 50 sccm and the electrolyte flow rate was maintained at 10 mL min. -1 The constant voltage method was used for testing, and the applied current density range was -1 to 0 V vs. RHE. The gas phase products were detected by gas chromatography, and the coulomb amount corresponding to the product concentration was calculated. The catalytic selectivity, activity and other data were obtained based on the total coulomb amount recorded by the electrochemical workstation. See the attached data for details. Figures 1 to 6 .
[0057] Figure 4The Faraday efficiency of each product of the CoPc / CNT electrode CO2 electroreduction catalyst prepared in this embodiment at different potentials in the CO2 electroreduction reaction catalyzed in a flow-type electrolyzer is shown. It can be seen that at each test current density, the products of the carbon dioxide electroreduction catalyst electrocatalyzing carbon dioxide reduction are only CO and a small amount of hydrogen. When the potential is -0.38V, the Faraday efficiency of CO reaches 94.8%.
[0058] It should be understood that the above examples are not limitations of the embodiments of the present invention. For ordinary technicians in this field, different forms of changes can be made based on the above description, and it is impossible to enumerate them all here. All related improvements and changes should fall within the scope of protection of the claims attached to the present invention.
Claims
1. A polyfluoroalkyl chain-modified cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst, characterized in that: The cobalt phthalocyanine molecule has the structure shown in the following formula: The cobalt phthalocyanine molecules are modified by polyfluoroalkyl chains and are combined with carbon nanotubes through π-π conjugation and / or physical adsorption.
2. The method for preparing the polyfluoroalkyl chain-modified cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst according to claim 1, characterized in that: The preparation method specifically comprises the following steps: (a) Appropriate amounts of 4-nitrophthalonitrile, imidazole, and potassium carbonate were weighed and placed in a Schlenk flask. N2 was purged three times to ensure an inert atmosphere in the reaction tube. DMF with a water content of ≤0.001% was then added, and the mixture was heated in an oil bath at 60°C for 24 h. After the reaction, the reaction solution was poured into deionized water to precipitate a light yellow solid. The precipitate was collected by filtration and rinsed with methanol until the filtrate was colorless. The precipitate was placed in a vacuum drying oven for 12 h and dried to obtain 4-imidazolylphthalonitrile, as shown in Formula (I): (b) The product of step a and cobalt acetate were placed in a Schlenk flask. After N2 was purged three times, n-pentanol was added as the reaction solvent, followed by the slow addition of DBU as a reaction catalyst, and the mixture was heated in an oil bath at 140°C for 48 hours. After the reaction, the mixture was cooled to room temperature and then filtered. The separated solid was washed with deionized water, acetone, and ethanol, respectively, until the filtrate was colorless. The precipitate was dried in a vacuum drying oven for 12 hours to obtain a phthalocyanine molecular precursor having a nitrogen-coordinated cobalt metal center, as shown in formula (II): (c) The product from step b and 1H,1H-tridecafluoro-1-iodoheptane were placed in a Schlenk flask, purged with N2 three times, and methanol with a water content of ≤0.001% was added. The mixture was heated in an 80°C oil bath for 24 h. After the reaction was completed, the mixture was naturally cooled to room temperature to precipitate blue crystals. The crystals were filtered and dissolved in a small amount of methanol. Subsequently, methyl tert-butyl ether was slowly added dropwise under ultrasound to gradually precipitate solids. After filtration and drying, a dark blue polyfluoroalkyl chain-modified cobalt phthalocyanine molecule was obtained, as shown in Formula (III):
3. The method for preparing the polyfluoroalkyl chain-modified cobalt phthalocyanine-carbon nanomaterial molecular electrocatalyst according to claim 2, wherein: In step (a), 2.60 g (15 mmol) of 4-nitrophthalonitrile, 1.22 g (18 mmol) of imidazole and 10.36 g (75 mmol) of potassium carbonate were weighed, and DMF (50 mL) having a moisture content of ≤0.001% was added; in step (b), 227.5 mg (0.5 mmol) of the product of step a, 132.7 mg (0.75 mmol) of cobalt acetate and 1 mL of DBU were added, and n-pentanol (5 mL) having a moisture content of ≤0.001% was added; in step (c), 167.0 mg (0.2 mmol) of the product of step b and 1137.6 mg (2.4 mmol) of 1H,1H-tridecafluoro-1-iodoheptane were added, and methanol (8 mL) having a moisture content of ≤0.001% was added.
4. The method for preparing the polyfluoroalkyl chain-modified cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst according to claim 3, characterized in that: The preparation method specifically comprises the following steps: (d) An appropriate amount of multi-walled carbon nanotube powder was weighed and added to 100 mL of concentrated hydrochloric acid, sonicated for 1 h, then stirred for 12 h, filtered, washed with deionized water until neutral, and then centrifuged and freeze-dried; (e) taking the product from step (d), adding 10 mL of DMF, and ultrasonicating using an ultrasonic cleaner for 30 min to obtain a uniformly dispersed carbon nanotube slurry; (f) taking the polyfluoroalkyl chain-modified cobalt phthalocyanine molecular product described in step (c), adding 10 mL of DMF, and ultrasonicating using an ultrasonic cleaner for 30 minutes to obtain a uniformly dispersed cobalt phthalocyanine molecular slurry; (g) taking equal volumes of the product of step (e) and step (f) and mixing them, stirring continuously for 20 to 30 hours to obtain a mixed solution g; (h) The mixed solution g is collected by suction filtration, and the obtained filtrate is washed and dried to obtain a cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst.
5. The method for preparing the polyfluoroalkyl chain-modified cobalt phthalocyanine-carbon nanomaterial molecular electrocatalyst according to claim 4, characterized in that: In step (d), 0.5 g of multi-walled carbon nanotube powder is weighed, 30 mg of the product of step (d) is taken in step (e), and 0.3 to 3 mg of the polyfluoroalkyl chain-modified cobalt phthalocyanine molecular product of step (c) is taken in step (f).
6. The method for preparing the polyfluoroalkyl chain-modified cobalt phthalocyanine-carbon nanomaterial molecular electrocatalyst according to claim 5, characterized in that: In step (f), preferably 1.5 mg of the polyfluoroalkyl chain-modified cobalt phthalocyanine molecular product of step (c) is taken.
7. A method for preparing a CoPc / CNT electrode, characterized in that: The steps include: Dispersing the cobalt phthalocyanine molecule-carbon nanomaterial molecular electrocatalyst prepared in claim 6 into 1 mL of a mixed solution of Nafion, water, and ethanol, and ultrasonicating for 30 minutes to obtain a uniform black catalyst slurry; Draw the black catalyst slurry and drop it onto a surface area of 1cm 2 On the carbon paper electrode, a working electrode film was formed by drying under moist room temperature conditions. The loading amount of CoPc / CNT was 0.1-1 mg cm -2 , forming a CoPc / CNT electrode.
8. The method for preparing the CoPc / CNT electrode according to claim 7, wherein: The volume ratio of the Nafion, water and ethanol is 2:49:
49.
9. The method for preparing the CoPc / CNT electrode according to claim 7, wherein: The loading amount of CoPc / CNT is 0.5 mg cm -2 .