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CN-122013245-A - Modified KCu3S2Material, preparation method and application thereof

CN122013245ACN 122013245 ACN122013245 ACN 122013245ACN-122013245-A

Abstract

The invention discloses a modified KCu 3 S 2 material, a preparation method and application thereof, wherein the modified KCu 3 S 2 material comprises KCu 3 S 2 and a surface modified lauric acid layer, the surface of KCu 3 S 2 is modified by coordinating hydroxyl and copper, the preparation method comprises the following steps of preparing KCu 3 S 2 precursor suspension, adding lauric acid, stirring and reacting for 3-6 hours at 60-100 ℃ to finish surface modification, collecting precipitate, washing and drying to obtain the KCu 3 S 2 material modified by lauric acid. According to the invention, a layer of lauric acid is introduced on the surface of the KCu 3 S 2 material, so that efficient and high-selectivity reduction of carbon dioxide can be catalyzed to prepare acetic acid.

Inventors

  • LU JUN
  • WANG QIAN
  • YU CHAO
  • JIANG DANFENG
  • WANG JING

Assignees

  • 江苏科技大学

Dates

Publication Date
20260512
Application Date
20260202

Claims (10)

  1. 1. A modified KCu 3 S 2 material is characterized by comprising KCu 3 S 2 and a surface modified lauric acid layer, wherein the surface modified lauric acid is obtained by coordinating hydroxyl groups and copper on the surface of KCu 3 S 2 .
  2. 2. The modified KCu 3 S 2 material of claim 1, wherein lauric acid is added in an amount of 5% -25% of the molar amount of copper during the surface modification of lauric acid.
  3. 3. The modified KCu 3 S 2 material as claimed in claim 1, wherein the added lauric acid is 10% -17% of the copper molar amount.
  4. 4. A method for preparing the modified KCu 3 S 2 material according to any one of claims 1 to 3, comprising the steps of: (1) Dissolving KOH in water, stirring uniformly to form an alkaline solution, sequentially adding copper salt and Na 2 S·9H 2 O, stirring until the solid is dissolved, adding hydrazine hydrate, stirring and reacting at 40-80 ℃ until the black color is changed into stable gray, and forming KCu 3 S 2 precursor suspension; (2) Adding lauric acid into the suspension after the reaction in the step (1), and stirring and reacting for 3-6 hours at 60-100 ℃ to finish surface modification; (3) And (3) after the reaction in the step (2), centrifugally collecting the precipitate, washing and drying to obtain the lauric acid modified KCu 3 S 2 material.
  5. 5. The method for preparing a modified KCu 3 S 2 material according to claim 4, wherein the molar ratio of copper to Na 2 S·9H 2 O in KOH and copper salts is 45-50:1:2-4.
  6. 6. The method for producing a modified KCu 3 S 2 material as claimed in claim 4, wherein in the step (1), the reaction time is 1 to 3 hours.
  7. 7. The method for producing a modified KCu 3 S 2 material as claimed in claim 4, wherein in the step (3), the drying is performed at 50-70℃for 4-8 hours in vacuum.
  8. 8. An application of the modified KCu 3 S 2 material according to any one of claims 1 to 3 in the reaction of electrocatalytic reduction of carbon dioxide to acetic acid.
  9. 9. The use according to claim 8, wherein the faraday efficiency of the reaction of carbon dioxide reduction to acetic acid is greater than 40%.
  10. 10. The method according to claim 8, wherein the electrocatalytic reaction is carried out in a flowing cell, the electrolyte is 0.5-2M KOH or KHCO 3 solution, the CO 2 gas flow rate is 20-50 sccm, and the operating potential is-0.5V to-1.2V vs RHE.

Description

Modified KCu 3S2 material and preparation method and application thereof Technical Field The invention relates to an electrocatalytic material and a preparation method and application thereof, in particular to a modified KCu 3S2 material and a preparation method and application thereof. Background As global greenhouse gas emissions continue to increase, electrocatalytic reduction technology of carbon dioxide has received attention because it can convert CO 2 to high value-added chemicals. In a multi-carbon product, acetic acid is taken as an important chemical raw material, has wide application prospect, but the generation of the acetic acid involves a complex eight-electron transfer and carbon-carbon coupling process, and has extremely high requirements on the active site structure and the local reaction microenvironment of the catalyst. Copper-based catalysts are the only metallic materials currently available to catalyze CO 2 to produce multi-carbon products. However, the conventional copper-based catalyst generally has the problems of selective dispersion of products in CO 2 RR, low Faraday efficiency of C 2+ products, poor stability and the like. In particular, acetic acid selectivity is typically less than 20% and is subject to structural reconstruction and activity decay at high current densities. In recent years, copper-based sulfides have demonstrated potential in CO 2 RR due to their unique electronic structure and tunable copper coordination environment. KCu 3S2, a typical copper sulfide, has high conductivity and structural stability, but its selectivity and activity in acetic acid production are still not ideal. Disclosure of Invention The invention aims at providing a modified KCu 3S2 material for preparing acetic acid by electrocatalytic CO 2 reduction with high efficiency and high selectivity, a second aim of the invention is to provide a preparation method of the modified KCu 3S2 material, and a third aim of the invention is to provide application of the modified KCu 3S2 material. The modified KCu 3S2 material comprises KCu 3S2 and a surface modified lauric acid layer, and is obtained by coordinating hydroxyl and copper to modify lauric acid on the surface of KCu 3S2. Preferably, lauric acid is added in the process of modifying the lauric acid surface, wherein the lauric acid is 5-25% of the molar quantity of copper. After the addition of lauric acid, the reaction path during the reduction of carbon dioxide is changed, and if a small or excessive amount of lauric acid is introduced, the acetic acid selection effect is affected. Further preferably, the lauric acid is added in an amount of 10% -17% of the molar amount of copper. The preparation method of the modified KCu 3S2 material comprises the following steps: (1) Dissolving KOH in water, stirring uniformly to form an alkaline solution, sequentially adding copper salt and Na 2S·9H2 O, stirring until the solid is dissolved, adding hydrazine hydrate, stirring and reacting at 40-80 ℃ until the black color is changed into stable gray, and forming KCu 3S2 precursor suspension; (2) Adding lauric acid into the suspension after the reaction in the step (1), and stirring and reacting for 3-6 hours at 60-100 ℃ to finish surface modification; (3) And (3) after the reaction in the step (2), centrifugally collecting the precipitate, washing and drying to obtain the lauric acid modified KCu 3S2 material. Preferably, the molar ratio of the KOH to the copper in the copper salt to the Na 2S·9H2 O is 45-50:1:2-4. Preferably, in step (1), the reaction time is 1 to 3 hours. Preferably, in step (2), the reaction temperature is 75-90 ℃ and the reaction is carried out for 2-4 hours. Preferably, in step (3), the washing is washing with deionized water and absolute ethanol, respectively. Preferably, in step (3), the drying is carried out at 50-70 ℃ for 4-8 hours. The invention relates to an application of a modified KCu 3S2 material in the reaction of generating acetic acid by electrocatalytic carbon dioxide reduction. Preferably, the faraday efficiency of the carbon dioxide reduction to acetic acid reaction is greater than 40%. The application method is that the electrocatalytic reaction is carried out in a flowing electrolytic cell, the electrolyte is 0.5-2M KOH or KHCO 3 solution, the gas flow rate of CO 2 is 20-50 sccm, and the working potential is-0.5V to-1.2V vs. RHE. The mechanism of the invention is that KCu 3S2 material is used as a catalyst to catalyze the reaction products of carbon dioxide, mainly HCOOH and H 2. According to the invention, a layer of lauric acid is introduced on the surface of the KCu 3S2 material, and it is unexpectedly found that the method can catalyze carbon dioxide to mainly generate acetic acid. This is probably because lauric acid, which is a long-chain fatty acid with good hydrophobicity and coordination ability, is introduced to the surface of KCu 3S2 catalyst, and can regulate the electrode-electrolyte interface microenviron