Preparation method and application of carbon dioxide gas capture functional molecule modified nanogold catalyst

Abstract

The invention discloses a preparation method and application of a carbon dioxide gas capture functional molecule modified nanogold catalyst. The preparation method comprises the following steps: synthesizing a modified molecule with a carbon dioxide gas capturing function through a chemical reaction; adding the modified molecules into an organic solvent, and uniformly mixing to obtain a solution; then adding a nanogold colloidal solution into the solution, uniformly stirring, and carrying out oil bath heating reaction; and after the reaction is completed, cooling to room temperature, carrying out suction filtration on the reaction liquid, respectively washing with ethanol and deionized water, and carrying out vacuum drying on the product to obtain the carbon dioxide gas capture functional molecule modified nanogold catalyst. In the electrocatalytic carbon dioxide reduction reaction process of the obtained catalyst, modification molecules are connected with the nanogold catalyst through chemical bonds, active sites of the nanogold catalyst are exposed, and meanwhile, an interface environment beneficial to the carbon dioxide reduction reaction can be provided; therefore, high activity, high selectivity and high stability of the molecular modified nanogold catalyst are realized.

Description

Technical Field

[0001] The invention belongs to the technical field of electrocatalytic materials, and in particular relates to a preparation method and application of a nano-gold catalyst modified with a carbon dioxide gas capturing functional molecule. Background Art

[0002] The electrocatalytic carbon dioxide reduction reaction (CO2RR) is an effective method to convert carbon dioxide (CO2) into renewable fuels or chemicals. This process uses renewable energy to reduce CO2 through electrochemical methods to obtain high-value-added fuels or chemicals. It has the advantages of sustainability and pollution-free, and is of great significance to achieving the strategic goals of "carbon peak and carbon neutrality".

[0003] In the electrocatalytic CO2RR process, due to the high activation barrier of CO2, low solubility in water, and the competitive hydrogen evolution reaction in the system, CO2RR still faces problems such as poor product selectivity and low Faradaic efficiency. Therefore, the development of highly active and highly selective 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 that uses organic molecules to modify the surface of copper catalysts 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 carbon nanotubes modified with nickel phthalocyanine molecules to achieve high CO selectivity 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, in practical applications they still face difficulties such as the difficulty in targeted customization of the molecular modification process, weak adhesion caused by the connection between molecules and nanomaterials through weak van der Waals interactions, and inevitable detachment or agglomeration of molecules under high current conditions, resulting in rapid deactivation and poor stability of the electrocatalysts. These problems seriously restrict the practical application of such electrocatalysts. Summary of the invention

[0006] In view of the above technical problems of existing molecular modified catalysts, the present invention provides a preparation method and application of a carbon dioxide gas capture functional molecule modified nano-gold catalyst, which has the characteristics of high activity, high selectivity and high stability.

[0007] The technical solution adopted by the present invention is: A method for preparing a carbon dioxide gas capture functional molecule modified nano-gold catalyst comprises the following steps: S1. Chemical reaction to synthesize modified molecules with carbon dioxide gas capture function; S2. adding the modified molecule obtained in S1 to an organic solvent and mixing them uniformly to obtain a solution; S3. According to the molar ratio of the modified molecule to the nano-gold catalyst of 2 to 5:1, the nano-gold colloidal solution was added to the solution obtained in S2, and the mixture was stirred and heated in an oil bath for reaction; S4. After the reaction is completed, cool to room temperature, filter the reaction solution, wash with ethanol and deionized water respectively, and vacuum dry the product to obtain a carbon dioxide gas capture functional molecule modified nano-gold catalyst.

[0008] Furthermore, in S2, the organic solvent is at least one of ethanol, dichloromethane, n-hexane, ethyl acetate, and toluene.

[0009] Furthermore, in S2, the solution concentration is 0.1 to 0.2 mol / L.

[0010] Furthermore, in S3, the reaction temperature is 30 to 140° C., and the reaction time is 6 to 12 hours.

[0011] The carbon dioxide gas capture functional molecule modified nano-gold catalyst obtained by the above preparation method is used as an electrocatalytic material in electrocatalytic carbon dioxide reduction.

[0012] Furthermore, the application method is specifically as follows: add isopropanol, deionized water and Nafion solution to the nano-gold catalyst modified with carbon dioxide gas capture functional molecules, disperse it evenly with ultrasound, drop-coat it on the surface of the glassy carbon electrode, and dry it to obtain a loaded molecule-modified catalyst electrode; use it as the working electrode, mercury / mercuric oxide as the reference electrode, platinum wire as the counter electrode, and 0.1 mol / L KHCO3 solution as the electrolyte, first introduce argon gas to saturation, and then introduce CO2 gas with the same time and flow rate as nitrogen, and test the linear scanning voltammetry curves under argon and CO2 atmosphere conditions, respectively.

[0013] Furthermore, hydrophobic carbon paper was used as the working electrode, and the carbon dioxide gas capture functional molecule modified catalyst was coated on the hydrophobic carbon paper. Mercury / mercuric oxide was used as the reference electrode, and the 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 CO2 was continuously introduced. The electrolysis reaction was carried out at different potentials to test the electrocatalytic carbon dioxide reduction performance.

[0014] The carbon dioxide gas capture functional molecule modified nano-gold catalyst of the present invention, in the CO2RR application process, the modified molecule with carbon dioxide gas capture function is connected to the nano-gold catalyst through a chemical bond, thereby enhancing the adhesion between the molecule and the nano-gold catalyst, and while exposing the active site of the nano-gold catalyst, an interface environment that is conducive to the carbon dioxide reduction reaction can be provided, thereby improving the catalytic activity, reaction selectivity and stability of the catalyst.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The carbon dioxide gas capture functional molecule modified nano-gold catalyst provided by the present invention is connected to the nano-gold catalyst by chemical bonds, which enhances the adhesion between the molecule and the nano-gold catalyst and provides an interface environment that is conducive to the carbon dioxide reduction reaction. When applied to electrocatalytic carbon dioxide reduction, it has high catalytic activity, high reaction selectivity and high stability for carbon dioxide reduction, providing a new idea for the development of high-efficiency carbon dioxide reduction electrocatalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of the modified molecule POSS-SS with CO2 gas capture function prepared in Example 1.

[0017] Figure 2 This is the linear sweep voltammetry curve of the nano-gold catalyst modified with CO2 gas capture functional molecules under carbon dioxide and argon conditions in Example 2.

[0018] Figure 3 This is the Faraday efficiency diagram of the nano-gold catalyst modified with CO2 gas capture functional molecules in Example 2.

[0019] Figure 4 It curve diagram of the molecularly modified nano-gold catalyst with CO2 gas capture function in Example 2 at -0.9V vs. RHE potential. DETAILED DESCRIPTION

[0020] The content of the present invention is further explained below in conjunction with specific embodiments, but the examples given do not limit the protection scope of the present invention. Example 1

[0021] The preparation method of a molecularly modified nano-gold catalyst having a CO2 gas capture function comprises the following steps: (1) Amino-substituted polysilsesquioxane compounds and lipoic acid were used as raw materials in a molar ratio of 2:1. The reaction was carried out at room temperature for 10-30 min under the catalytic conditions of 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) to synthesize a modified molecule POSS-SS with CO2 gas capture function. The H-NMR spectrum showed Figure 1 As shown;

[0022] (2) Weigh 2.124 g of the modified molecule POSS-SS and dissolve it in 20.0 mL of dichloromethane to obtain a 0.1 mol / L solution; (3) Transfer the solution from step (2) to a round-bottom flask, add 20.0 mL of 0.05 mol / L nanogold colloidal solution, stir evenly, heat in an oil bath to 60°C, and react for 12 h; (4) After the reaction was completed, the reaction mixture was cooled to room temperature, the reaction solution was filtered, and washed three times with ethanol and deionized water respectively. The resulting solid was vacuum dried at 60 °C for 24 h to obtain a molecularly modified nano-gold catalyst with CO2 gas capture function. Example 2

[0023] Application of a nano-gold catalyst modified with CO2 gas capture functional molecules in electrocatalytic carbon dioxide reduction, the method is as follows: Take the molecularly modified nano-gold catalyst (5 mg) with CO2 gas capture function prepared in Example 1, add isopropanol (700 μL), deionized water (250 μL) and Nafion solution (50 μL, 5.0 wt%), and disperse evenly by ultrasonication for 20 min to obtain a catalyst slurry dispersion. Pipette 10 μL of the dispersion droplet onto the glassy carbon electrode and dry it in an infrared lamp oven to obtain a loaded molecularly modified nano-gold catalyst electrode.

[0024] A 0.1 mol / L KHCO3 solution was added to an H-type electrolytic cell, and a three-electrode system was formed with a nano-gold catalyst electrode modified with CO2 gas capture functional molecules as the working electrode, a platinum wire as the counter electrode, and a mercury / mercuric oxide electrode as the reference electrode. Argon gas with a flow rate of 25 sccm was introduced to the cathode at room temperature for 30 min, and then CO2 was introduced with the same time and flow rate as argon gas. The linear sweep voltammetry curves ( Figure 2 ), by comparison, it can be found that the electrode exhibits a higher current density under carbon dioxide atmosphere conditions, indicating that the molecularly modified nano-gold catalyst has significant electrocatalytic carbon dioxide reduction performance.

[0025] The working electrode was replaced with hydrophobic carbon paper, and 200 μL of the catalyst dispersion prepared in step (1) was evenly coated on the hydrophobic carbon paper substrate and dried under an infrared lamp oven. The carbon paper area was about 1 cm 2 The molecular modified catalyst loading is about 1 mg / cm 2 .

[0026] The CO2 reduction performance was tested in an H-type electrolytic cell using a three-electrode system (hydrophobic carbon paper loaded with molecularly modified nanogold catalyst as the working electrode, graphite rod as the counter electrode, and mercury / mercury oxide electrode as the reference electrode). The electrolyte was pre-saturated with CO2, and the CO2 flow rate was maintained at 25 sccm. The electrolysis reaction was carried out at different potentials, and the concentrations of the gas phase product and the liquid phase product were tested by gas chromatography and liquid chromatography, respectively.

[0027] like Figure 3 As shown, the Faraday efficiency of the molecule-modified nanogold catalyst with CO2 gas capture function was obtained by calculation. The molecule-modified nanogold catalyst has a high selectivity for CO. At -0.9V, the hydrogen evolution efficiency is the lowest and the CO production efficiency is the highest, indicating that the molecule with CO2 gas capture function can increase the CO2 concentration at the catalytic interface and improve the interfacial hydrophobicity of the nanogold catalyst. The hydrophobic microenvironment can significantly enhance the CO2 gas diffusion and effectively reduce the competitive side reaction of hydrogen evolution, thereby improving the catalyst selectivity.

[0028] like Figure 4 As shown, the it curve at -0.9 V vs. RHE potential shows no obvious decay of the current density signal within 35 min, indicating that the molecularly modified nanogold catalyst has high stability.

Claims

1. A method for preparing a carbon dioxide gas capture functional molecule modified nano-gold catalyst, characterized in that: The steps include: S1. Chemical reaction to synthesize modified molecules with carbon dioxide gas capture function; S2. adding the modified molecule obtained in S1 to an organic solvent and mixing them uniformly to obtain a solution; S3. According to the molar ratio of the modified molecule to the nano-gold catalyst of 2 to 5:1, the nano-gold colloidal solution was added to the solution obtained in S2, and the mixture was stirred and heated in an oil bath for reaction; S4. After the reaction is completed, the reaction solution is cooled to room temperature, filtered, washed with ethanol and deionized water respectively, and the product is vacuum dried to obtain a carbon dioxide gas capture functional molecule modified nano-gold catalyst.

2. The method for preparing the carbon dioxide gas capture functional molecule modified nano-gold catalyst 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 capture functional molecule modified nano-gold catalyst 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 capture functional molecule modified nano-gold catalyst according to claim 1, characterized in that: In S3, the reaction temperature is 30 to 140°C, and the reaction time is 6 to 12 hours.

5. Use of the carbon dioxide gas capture 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 use according to claim 5, characterized in that: The specific application method is as follows: add isopropanol, deionized water and Nafion solution to the nano-gold catalyst modified with carbon dioxide gas capture functional molecules, and disperse it evenly with ultrasound to obtain the loaded molecule modified catalyst; use it as the working electrode, mercury / mercuric oxide as the reference electrode, platinum wire as the counter electrode, and 0.1 mol / L KHCO3 solution as the electrolyte, first introduce argon gas to saturation, and then introduce CO2 gas with the same time and flow rate as nitrogen, and test the linear sweep voltammetry curves under argon and CO2 atmosphere conditions, respectively.

7. The use according to claim 5, characterized in that: Using hydrophobic carbon paper as the working electrode, the carbon dioxide gas capture functional molecule modified catalyst is coated on the hydrophobic carbon paper, mercury / mercuric oxide is used as the reference electrode, the graphite rod is used as the counter electrode, and 0.1 mol / L KHCO3 solution is used as the electrolyte. CO2 is introduced until saturation, and CO2 is continuously introduced. The electrolysis reaction is carried out at different potentials to test the electrocatalytic carbon dioxide reduction performance.

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