Preparation method of carbon dioxide gas capturing functional molecule modified nano-gold catalyst and application thereof

Abstract

The application discloses a preparation method of a carbon dioxide gas capturing functional molecule modified nano-gold catalyst and application thereof. The preparation method is as follows: first, a modification molecule with a carbon dioxide gas capturing function is synthesized through a chemical reaction; then, the modification molecule is added into an organic solvent to obtain a solution after being uniformly mixed; then, a nano-gold colloid solution is added into the solution, and the mixture is uniformly stirred and then heated to react in an oil bath; after the reaction is completed, the mixture is cooled to room temperature, and the reaction liquid is extracted, washed with ethanol and deionized water respectively, and vacuum dried to obtain the carbon dioxide gas capturing functional molecule modified nano-gold catalyst. In the process of electrocatalytic reduction of carbon dioxide, the modification molecule and the nano-gold catalyst are connected through a chemical bond, the active sites of the nano-gold catalyst are exposed, and an interface environment beneficial to the reduction of carbon dioxide can be provided, so that the high activity, high selectivity and high stability of the molecule modified nano-gold catalyst are realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrocatalytic materials, and particularly relates to a preparation method of a carbon dioxide gas capturing functional molecule modified nanogold catalyst and application thereof. BACKGROUND

[0002] The electrocatalytic carbon dioxide reduction reaction (CO2RR) is an effective method for converting carbon dioxide (CO2) into renewable fuels or chemicals. The process uses renewable energy to reduce CO2 electrochemically to obtain high-value fuels or chemicals, has the advantages of sustainability and no pollution, and has important significance for achieving the strategic goal of "carbon peak and carbon neutral".

[0003] In the process of electrocatalytic CO2RR, CO2RR still faces problems such as poor product selectivity and low faradic efficiency due to the high activation energy barrier of CO2, low solubility in water, and the existence of competitive hydrogen evolution reaction in the system. Therefore, developing high-activity and high-selectivity CO2RR electrocatalysts has become a research hotspot in the field of electrochemistry.

[0004] Molecularly modified catalysts have the advantages of structural diversity, functional designability, and clear active sites, and are widely used in the field of electrocatalytic CO2RR. Organic molecules can easily modify the surface of nanomaterials through self-assembly strategies to construct molecularly modified catalysts with specific interface structures. For example, Sargent et al. reported a molecular regulation mechanism for surface modification of copper catalysts by organic molecules to achieve directional regulation of electrochemical CO2RR selectivity (Nat. Catal. 2020, 3, 75); Liang Yongye et al. developed a series of molecularly modified electrocatalysts of phthalocyanine nickel modified carbon nanotubes, which achieved high selectivity of CO at high current density (Nat. Energy, 2020, 5, 684).

[0005] Although molecularly modified nanomaterial electrocatalysts can effectively improve the performance of electrocatalytic carbon dioxide reduction, they still face difficulties in practical applications, such as the difficulty of targeted customization in the molecular modification process, the weak adhesion caused by the weak van der Waals interaction between the molecules and the nanomaterials, and the inevitable detachment or aggregation of the molecules under high current conditions, which leads to rapid deactivation and poor stability of the electrocatalysts, seriously restricting the practical process of such electrocatalysts. SUMMARY

[0006] In view of the above technical problems of existing molecularly modified catalysts, the application provides a preparation method of a carbon dioxide gas capturing functional molecule modified nanogold catalyst and application thereof, which has the characteristics of high activity, high selectivity and high stability.

[0007] The technical scheme adopted by the application is:

[0008] A preparation method of a carbon dioxide gas capturing functional molecule modified nanogold catalyst, comprising the following steps:

[0009] S1. chemically reacting to synthesize a modification molecule with a carbon dioxide gas capturing function;

[0010] S2. adding the modification molecule obtained in S1 into an organic solvent to obtain a solution;

[0011] S3. adding a nanogold colloid solution into the solution obtained in S2 according to a molar ratio of the modification molecule to the nanogold catalyst of 2-5:1, and stirring uniformly and then heating and reacting in an oil bath;

[0012] S4. cooling to room temperature after the reaction is completed, and then extracting and filtering the reaction solution, washing with ethanol and deionized water respectively, and vacuum drying the product to obtain a carbon dioxide gas capturing functional molecule modified nanogold catalyst.

[0013] Further, in S2, the organic solvent is at least one of ethanol, dichloromethane, n-hexane, ethyl acetate and toluene.

[0014] Further, in S2, the concentration of the solution is 0.1-0.2 mol / L.

[0015] Further, in S3, the reaction temperature is 30-140℃, and the reaction time is 6-12 hours.

[0016] The carbon dioxide gas capturing functional molecule modified nanogold catalyst obtained by the above preparation method is applied as an electrocatalytic material in electrocatalytic reduction of carbon dioxide.

[0017] Further, the application method specifically comprises: adding isopropyl alcohol, deionized water and a Nafion solution into the carbon dioxide gas capturing functional molecule modified nanogold catalyst, ultrasonic dispersion, drop coating on the surface of a glassy carbon electrode, drying to obtain a molecule modified catalyst electrode; taking the molecule modified catalyst electrode as a working electrode, mercury / mercury oxide as a reference electrode, a platinum wire as a counter electrode, and 0.1 mol / L KHCO3 solution as an electrolyte, first saturating with argon, then saturating with CO2 gas with the same time and flow rate as nitrogen, and testing linear sweep voltammetry curves under argon and CO2 atmospheres respectively.

[0018] Further, taking a hydrophobic carbon paper as a working electrode, coating the carbon dioxide gas capturing functional molecule modified catalyst on the hydrophobic carbon paper, taking mercury / mercury oxide as a reference electrode, taking a graphite rod as a counter electrode, and taking 0.1 mol / L KHCO3 solution as an electrolyte, saturating with CO2, continuously saturating with CO2, and testing electrocatalytic carbon dioxide reduction performance under different potentials.

[0019] The carbon dioxide gas capturing functional molecule modified nano-gold catalyst of the present application has the modified molecule with carbon dioxide gas capturing function connected with the nano-gold catalyst through a chemical bond, thereby enhancing the adhesion of the molecule and the nano-gold catalyst, exposing the active sites of the nano-gold catalyst while providing an interface environment conducive to the carbon dioxide reduction reaction, and improving the catalytic activity, reaction selectivity and stability of the catalyst.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] The carbon dioxide gas capturing functional molecule modified nano-gold catalyst provided by the present application has the modified molecule connected with the nano-gold catalyst through a chemical bond, thereby enhancing the adhesion of the molecule and the nano-gold catalyst and providing an interface environment conducive to the carbon dioxide reduction reaction. When applied to the electrocatalytic reduction of carbon dioxide, the catalyst has high catalytic activity, high reaction selectivity and high stability for carbon dioxide reduction, thereby providing a new idea for the development of high-efficiency carbon dioxide reduction electrocatalysts. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The 1H-NMR spectrum of the modified molecule with CO2 gas capturing function prepared for Example 1.

[0023] Figure 2 The linear sweep voltammetry curve of the nano-gold catalyst modified with the CO2 gas capturing functional molecule of Example 2 under carbon dioxide and argon conditions.

[0024] Figure 3 The Faraday efficiency diagram of the nano-gold catalyst modified with the CO2 gas capturing functional molecule of Example 2.

[0025] Figure 4 The it curve diagram of the nano-gold catalyst modified with the CO2 gas capturing functional molecule of Example 2 at a potential of -0.9 V vs. RHE. DETAILED DESCRIPTION

[0026] The content of the present application will be further illustrated below in combination with specific examples, but the examples do not limit the protection scope of the present application. Example 1

[0027] The preparation method of the nano-gold catalyst modified with the CO2 gas capturing functional molecule comprises the following steps:

[0028] (1) Amino-substituted polysilsesquioxane compound and thioctic acid were used as raw materials, the molar ratio was 2:1, and the reaction was carried out at room temperature for 10-30 min under the catalysis of 1-ethyl-(3-dimethylaminopropyl) carbodiimide (EDC), to synthesize the modified molecule POSS-S-S with CO2 gas capture function, and the nuclear magnetic hydrogen spectrum is as shown in Figure 1 ;

[0029]

[0030] (2) 2.124 g of the modified molecule POSS-S-S was weighed and dissolved in 20.0 mL of dichloromethane to obtain a 0.1 mol / L solution;

[0031] (3) The solution in step (2) was transferred to a round-bottom flask, 20.0 mL of 0.05 mol / L nano gold colloid solution was added, and the mixture was stirred uniformly, and then heated to 60°C in an oil bath for 12 h;

[0032] (4) After the reaction was completed, the reaction liquid was cooled to room temperature, and then filtered, washed with ethanol and deionized water for 3 times respectively, and the obtained solid was dried at 60°C under vacuum for 24 h to obtain the nano gold catalyst modified with the CO2 gas capture functional molecule. Example 2

[0033] The application of the nano gold catalyst modified with the CO2 gas capture functional molecule in electrocatalytic reduction of carbon dioxide is as follows:

[0034] The nano gold catalyst modified with the CO2 gas capture functional molecule (5 mg) prepared in Example 1 was added into isopropanol (700 μL), deionized water (250 μL) and Nafion solution (50 μL, 5.0 wt%), and then ultrasonically dispersed for 20 min to obtain a catalyst slurry dispersion. 10 μL of the dispersion was dropped onto a glassy carbon electrode, and then dried in an infrared lamp oven to obtain a nano gold catalyst electrode loaded with the modified molecule.

[0035] A 0.1 mol / L KHCO3 solution was added into an H-type electrolytic cell, a nano gold catalyst electrode loaded with the CO2 gas capture functional molecule was used as a working electrode, a platinum wire was used as a counter electrode, and a mercury / mercury oxide electrode was used as a reference electrode to form a three-electrode system. Argon gas with a flow rate of 25 sccm was introduced into the cathode for 30 min at room temperature, and then CO2 with the same flow rate and time as the argon gas was introduced, and linear sweep voltammetry curves (LSV) under argon and CO2 atmospheres were tested, respectively. Figure 2 Through comparison, it can be found that the electrode shows a higher current density under the carbon dioxide atmosphere, indicating that the nano gold catalyst modified with the molecule has a significant electrocatalytic carbon dioxide reduction performance.

[0036] The working electrode is replaced with a hydrophobic carbon paper, 200 μL of the catalyst dispersion prepared in step (1) is evenly coated on the hydrophobic carbon paper substrate, and dried in an infrared lamp oven. Among them, the area of the carbon paper is about 1 cm 2 , and the molecular modified catalyst loading is about 1 mg / cm 2 .

[0037] The CO2 reduction performance is tested in an H-type electrolysis cell using a three-electrode system (hydrophobic carbon paper loaded with molecular modified nanogold catalyst as working electrode; graphite rod as counter electrode; mercury / mercury oxide electrode as reference electrode). The electrolyte is pre-inflated with CO2 to saturation, and the CO2 flow is maintained at 25 sccm. The electrolysis reaction is carried out at different potentials, and the concentrations of gaseous and liquid products are tested by gas chromatography and liquid chromatography, respectively.

[0038] As shown in Figure 3 , the Faraday efficiency of the molecular modified nanogold catalyst with CO2 gas capture function is obtained by calculation. The molecular modified nanogold catalyst has high selectivity for CO. At-0.9 V, the hydrogen evolution efficiency is the lowest and the CO production efficiency is the highest, indicating that the CO2 gas capture function molecule can increase the CO2 concentration at the catalytic interface and improve the interface hydrophobicity of the nanogold catalyst. The hydrophobic microenvironment can significantly enhance CO2 gas diffusion and effectively reduce the competitive side reaction of hydrogen evolution, improving the selectivity of the catalyst.

[0039] As shown in Figure 4 , the it curve graph at-0.9 V vs. RHE potential shows that the current density signal does not decay significantly within 35 min, indicating that the molecular modified nanogold catalyst has high stability.

Claims

1. A method for preparing a carbon dioxide gas-capturing functional molecule-modified gold nanoparticle catalyst, characterized in that, Includes the following steps: S1. A modified molecule with carbon dioxide gas capture function is synthesized by chemical reaction. The structure of the modified molecule is shown below: ； S2. Add the modified molecule obtained in S1 to an organic solvent and mix thoroughly to obtain a solution; S3. Add the gold nanoparticle colloidal solution to the solution obtained in S2 according to the molar ratio of the modified molecule to the gold nanoparticle catalyst of 2 to 5:1, stir evenly, and then heat the reaction in an oil bath. S4. After the reaction is complete, cool to room temperature, filter the reaction solution, wash with ethanol and deionized water respectively, and vacuum dry the product to obtain the carbon dioxide gas-capturing functional molecule modified gold nanocatalyst.

2. The method for preparing the carbon dioxide gas-capturing functional molecule-modified gold nanocatalyst according to claim 1, characterized in that, In S2, the organic solvent is at least one of ethanol, dichloromethane, n-hexane, ethyl acetate, and toluene.

3. The method for preparing the carbon dioxide gas-capturing functional molecule-modified gold nanocatalyst according to claim 1, characterized in that, In S2, the concentration of the solution is 0.1–0.2 mol / L.

4. The method for preparing the carbon dioxide gas-capturing functional molecule-modified gold nanocatalyst according to claim 1, characterized in that, In S3, the reaction temperature is 30–140℃ and the reaction time is 6–12 hours.

5. The application of the carbon dioxide gas-capturing functional molecule-modified nano-gold catalyst obtained by the preparation method according to any one of claims 1 to 4 as an electrocatalytic material in electrocatalytic carbon dioxide reduction.

6. The application according to claim 5, characterized in that, The specific application method is as follows: Isopropanol, deionized water and Nafion solution are added to the carbon dioxide gas capture functional molecule modified gold nanocatalyst, and the mixture is ultrasonically dispersed to obtain a catalyst slurry dispersion. This dispersion is then drop-coated onto a glassy carbon electrode and dried to obtain a supported molecule modified gold nanocatalyst electrode. Using it as the working electrode, mercury / mercury oxide as the reference electrode, platinum wire as the counter electrode, and 0.1 mol / L KHCO3 solution as the electrolyte, argon gas was first introduced until saturation, and then CO2 gas was introduced for the same time and flow rate as argon gas. The linear sweep voltammetric curves were tested under argon gas and CO2 atmosphere conditions, respectively.

7. The application according to claim 5, characterized in that, Hydrophobic carbon paper was used as the working electrode. A nano-gold catalyst modified with carbon dioxide gas-capturing functional molecules was coated onto the hydrophobic carbon paper. Mercury / mercury oxide was used as the reference electrode, and a graphite rod was used as the counter electrode. 0.1 mol / L KHCO3 solution was used as the electrolyte. CO2 was introduced until saturation and then continuously introduced. Electrolysis reactions were carried out at different potentials to test the electrocatalytic carbon dioxide reduction performance.

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