Basic ionic liquid functionalized copper and its application in electrocatalytic carbon dioxide reduction to produce multi-carbon products

Abstract

The application discloses basic ionic liquid functionalized copper and application of the basic ionic liquid functionalized copper in electrocatalytic carbon dioxide reduction for preparing multi-carbon products. A preparation method of the basic ionic liquid functionalized copper comprises the following steps: S1, mixing borax, sodium ascorbate, an ionic liquid and copper chloride and then performing reaction; the ionic liquid is 1-ammonia propyl-3-methyl imidazole bromide, 1-propyl-3-methyl imidazole bromide or 1-propyl-3-methyl imidazole nitrate; S2, performing electro-reduction on a product of the reaction to obtain the basic ionic liquid functionalized copper. The basic ionic liquid functionalized copper prepared by the method can be used as an electrocatalyst to electrocatalytically reduce CO2 to prepare multi-carbon products. The Cu@AIL provided by the application has excellent catalytic activity in electrocatalytic reduction of CO2 to multi-carbon products under mild conditions.

Description

Technical Field

[0001] This invention relates to a basic ionic liquid-functionalized copper and its application in the electrocatalytic reduction of carbon dioxide to prepare multi-carbon products, belonging to the field of chemical technology. Background Technology

[0002] The overuse of traditional fossil fuels has led to excessive CO2 emissions. High CO2 concentrations in the air disrupt the natural carbon cycle, causing a series of environmental problems such as global warming, sea-level rise, and ocean acidification. Reducing atmospheric CO2 concentrations is one of the major challenges facing humanity today.

[0003] Among numerous CO2 conversion technologies, electrocatalytic CO2 reduction is considered an important pathway for achieving clean and efficient CO2 utilization because it can utilize electricity generated from renewable energy sources and convert CO2 into economically viable chemical products under ambient temperature and pressure conditions. Electrocatalytic CO2 reduction can reduce CO2 to single-carbon products (carbon monoxide, methane, formic acid, methanol) and multi-carbon products (ethylene, ethanol, propanol, acetic acid, etc.). Multi-carbon products have attracted widespread attention from researchers due to their higher energy density and industrial value. However, the current efficiency of electrocatalytic CO2 reduction in preparing multi-carbon products is relatively low, still far from meeting the requirements for industrial production. Developing high-performance catalysts is an effective way to solve this problem.

[0004] Currently, copper-based catalysts are considered the most suitable metals for preparing multi-carbon products due to their appropriate adsorption strength for CO2 reduction intermediates. Researchers have attempted to improve the CO2 reduction performance of copper-based catalysts by altering the surface atomic properties of copper through various research strategies, such as surface modification, doping with heteroatoms, defects, morphology adjustment, and crystal plane engineering. Among these strategies, surface modification is considered an effective method because it can control the concentration of reactants on the catalyst surface and regulate the adsorption strength of intermediates. Ionic liquids, as novel green solvents, are widely used as electrolytes in the electrocatalytic reduction of CO2; however, their high viscosity and high cost limit their widespread application. Therefore, developing ionic liquid-functionalized copper-based catalyst systems to achieve efficient electrocatalytic CO2 reduction for the preparation of multi-carbon products is a significant but challenging research topic. Summary of the Invention

[0005] The purpose of this invention is to provide a copper (Cu@AIL) functionalized with a zwitterionic liquid, which can electrocatalyze the reduction of CO2 to multi-carbon products under mild conditions and has excellent catalytic activity.

[0006] The method for preparing alkaline ionic liquid-functionalized copper provided by the present invention includes the following steps:

[0007] S1. Borax, sodium ascorbate, ionic liquid and copper chloride are mixed and reacted.

[0008] The ionic liquid is 1-aminopropyl-3-methylimidazolium bromide, 1-propyl-3-methylimidazolium bromide, or 1-propyl-3-methylimidazolium nitrate;

[0009] S2. The product of the reaction is obtained by electroreduction.

[0010] In the above preparation method, in step S1, the molar ratio of sodium ascorbate to copper chloride is 1:1 to 5;

[0011] Specifically, in step S1, in the mixed aqueous solution of borax, sodium ascorbate, ionic liquid, and copper chloride, the molar concentration of borax is 0.05–0.2 mol / L, the molar concentration of sodium ascorbate is 0.02–0.2 mol / L, the molar concentration of the ionic liquid is 0.005–0.01 mol / L, and the molar concentration of copper chloride is 0.01–0.05 mol / L.

[0012] In the above preparation method, in step S1, the reaction temperature is 10-40℃ and the time is 0-2h, but not zero.

[0013] The above preparation method further includes the following steps:

[0014] The reaction system after the reaction is centrifuged to collect the solid product, which is then washed with water, dried, and then subjected to the electroreduction.

[0015] In the above preparation method, in step S2, the current density of the electroreduction is 0.1–1.0 A cm⁻¹. -2 .

[0016] The basic ionic liquid functionalized copper prepared by the method of this invention can be used as an electrocatalyst to electrocatalyze the reduction of CO2 to prepare multi-carbon products.

[0017] Furthermore, the present invention also provides a method for preparing multi-carbon products by CO2 reduction, comprising the following steps:

[0018] Under mild conditions, copper functionalized with the alkaline ionic liquid is dispersed in an electrolyte and electrocatalyzed to reduce CO2 to obtain multi-carbon products such as ethylene, ethanol, propanol, and acetic acid.

[0019] Here, mild conditions refer to conditions at room temperature and normal pressure;

[0020] The electrolyte can be an aqueous solution of potassium hydroxide or an aqueous solution of potassium bicarbonate, with a concentration of 0.1–2 M.

[0021] The current density of the electrocatalytic CO2 reduction reaction is 0.01–2.0 A cm⁻¹. -2 .

[0022] The Cu@AIL provided by this invention exhibits excellent catalytic activity for the electrocatalytic reduction of CO2 to multi-carbon products under mild conditions. Attached Figure Description

[0023] Figure 1 The X-ray diffraction pattern of Cu@AIL obtained in Example 1 of this invention ( Figure 1 (a) Scanning electron microscope images ( Figure 1 (b), scale bar at 500 nm), transmission electron microscope image ( Figure 1 (c), scale bar at 50 nm) and high-power transmission electron microscope images ( Figure 1 (d), scale bar is 1.5 nm).

[0024] Figure 2 The X-ray diffraction pattern of Cu (without ionic liquid) prepared in Comparative Example 1 of this invention is shown below. Figure 2 (a) and scanning electron microscope images ( Figure 2 (b), scale bar is 300nm).

[0025] Figure 3 The X-ray photoelectron spectra of Cu@AIL prepared in Example 1 and Cu prepared in Comparative Example 1 are shown. Figure 3 (a) Infrared spectra of Cu@AIL and alkaline ionic liquid (AIL) Figure 3 (b) Synchrotron X-ray absorption near-edge structure spectrum of Cu's K-side ( Figure 3 (c) and the K-edge synchrotron X-ray absorption extended edge structure spectrum of Cu ( Figure 3 (d)).

[0026] Figure 4 The diagram shows the current density of Cu@AIL in Example 1 and Cu at different potentials in Comparative Example 1 of this invention. Figure 4 (a) Curves showing the Faradaic efficiency of electrocatalytic CO2 reduction to multi-carbon products as a function of current density. Figure 4 (b) Curves showing the half-cell energy efficiency of Cu@AIL in Example 1 and Cu in Comparative Example 1 as a function of current density. Figure 4 (c) Electrochemical impedance spectroscopy of Cu@AIL in Example 1 and Cu in Comparative Example 1 of the present invention ( Figure 4 (d)). Detailed Implementation

[0027] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0028] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0029] Example 1

[0030] In this embodiment, Cu@AIL is prepared by dissolving 1-aminopropyl-3-methylimidazolium bromide and sodium ascorbate in an aqueous solution of borax, followed by vigorous stirring, then adding copper chloride, and finally coating the resulting solid product onto carbon paper at a depth of 0.5 Å. -2 It was obtained by reduction at a current density.

[0031] The specific steps are as follows:

[0032] First, borax is dissolved in deionized water. Then, 1-aminopropyl-3-methylimidazolium bromide and sodium ascorbate dissolved in the borax aqueous solution are added. The mixture is then stirred vigorously, and copper chloride is added to the solution. The reaction is carried out at room temperature for 0.5 h to obtain the precursor Cu2O@AIL.

[0033] In the aqueous solution, the molar concentration of borax was 0.075 mol / L, the molar concentration of sodium ascorbate was 0.057 mol / L, the molar concentration of 1-aminopropyl-3-methylimidazolium bromide was 0.0065 mol / L, and the molar concentration of copper chloride was 0.037 mol / L; the molar ratio of sodium ascorbate to copper chloride was 1:1.54.

[0034] The precursor Cu2O@AIL was dissolved in 1M potassium hydroxide solution at 0.5A cm⁻¹. -2 Cu@AIL can be obtained by electroreduction at current density.

[0035] The Cu@AIL material was analyzed by transmission electron microscopy, high-resolution transmission electron microscopy, and X-ray diffraction, respectively. The results are as follows: Figure 1 As shown.

[0036] Figure 1 The positions of the diffraction peaks in the X-ray diffraction pattern of (a) are consistent with the diffraction peaks of metallic copper (JCPDS#04-0836), indicating that Cu was successfully synthesized. Figure 1 (b) and Figure 1 (c) shows scanning electron microscope and transmission electron microscope images that reveal the morphology of irregular nanoparticles. Figure 1 (d) The high-resolution transmission electron microscope image shows that the lattice spacing is 0.21 nm, corresponding to the (111) crystal plane of Cu.

[0037] Comparative Example 1

[0038] In this comparative example of Cu, firstly, borax was dissolved in deionized water, then sodium ascorbate dissolved in the borax aqueous solution was added, followed by vigorous stirring, and copper chloride was added to the above solution. The reaction was carried out at room temperature to obtain the precursor Cu2O.

[0039] Cu can be obtained by electroreduction of the precursor Cu2O in potassium hydroxide solution.

[0040] The specific steps are as follows:

[0041] First, borax is dissolved in deionized water, then sodium ascorbate dissolved in the borax aqueous solution is added. After vigorous stirring, copper chloride is added to the above solution and reacted at room temperature to obtain the precursor Cu2O.

[0042] The precursor Cu₂O was dissolved in a 1M potassium hydroxide solution at 0.5A cm⁻¹. -2 Cu can be obtained by electroreduction under current density.

[0043] The Cu material was characterized by X-ray diffraction and scanning electron microscopy, respectively, and the results are as follows: Figure 2 As shown.

[0044] Figure 2 The X-ray diffraction pattern of (a) is consistent with the diffraction peak of metallic copper (JCPDS#04-0836), indicating that Cu was successfully synthesized. The scanning electron microscope images show that Cu exhibits a nanoparticle morphology. Figure 2 (b)).

[0045] X-ray photoelectron spectroscopy, infrared spectroscopy, synchrotron X-ray absorption near-edge structure spectroscopy, and synchrotron X-ray absorption extended edge structure analysis were performed on Cu@AIL and Cu materials, respectively. The results are as follows: Figure 3 As shown.

[0046] The chemical and structural information of Cu@AIL and Cu was investigated using X-ray photoelectron spectroscopy. The 2p orbital of Cu@AIL was shifted towards lower wavenumbers compared to Cu, indicating an interaction between 1-aminopropyl-3-methylimidazolium bromide and Cu in Cu@AIL. Infrared spectroscopy of Cu@AIL and 1-aminopropyl-3-methylimidazolium bromide was used to further characterize the structure of Cu@AIL. (1389 cm⁻¹) -1 1462cm -1 and 2932cm -1 Paramagnetic resonance (PMR) curves were further used to determine the chemical and structural information of the catalyst. The Cu@AIL infrared spectrum at 1389 cm⁻¹... -1 1462cm -1 and 2932cm -1The characteristic absorption peak at the point proves that the alkaline ionic liquid has been successfully introduced into Cu@AIL.

[0047] Furthermore, the K of Cu in the material was further characterized using synchrotron X-ray absorption near-edge structure spectroscopy (XANES) and synchrotron X-ray absorption extended edge structure spectroscopy, and the results are as follows: Figure 3 (c) and Figure 3 As shown in (d), synchrotron X-ray absorption near-edge structure spectroscopy (XANES) results show that Cu@AIL and Cu have the same characteristic diffraction peaks as metallic copper foil, proving that the chemical valence state of copper in Cu@AIL and Cu is 0. Figure 3 (d), Cu@AIL in The weak absorption peak corresponds to the Cu-N bond, which proves that the ionic liquid has been successfully introduced into Cu@AIL.

[0048] Example 2

[0049] The Cu@AIL material of Example 1 and the Cu of Comparative Example 1 were used for electrocatalytic CO2 reduction tests.

[0050] The specific implementation steps are as follows:

[0051] The Cu@AIL prepared in Example 1 and the Cu material prepared in Comparative Example 1 were used for electrocatalytic CO2 reduction reaction testing. The electrolyte was a 1 mol / L KOH aqueous solution. The reaction results are as follows. Figure 4 As shown.

[0052] Figure 4 Curves showing the current density versus potential for Cu@AIL prepared in Example 1 and Cu prepared in Comparative Example 1 at different potentials. Figure 4 (a) It can be seen that Cu@AIL exhibits a larger current density compared to Cu, which indicates that Cu@AIL has better electrocatalytic CO2 reduction activity.

[0053] Figure 4 (b) This paper demonstrates the Faraday efficiency of the electroreduction of CO2 to multi-carbon products by Cu@AIL prepared in Example 1 and Cu in Comparative Example 1 at different current densities. It can be seen that at 0.9 A cm⁻¹... -2 At a current density of 0.3 A cm⁻¹, the Cu@AIL electrocatalytic reduction of CO₂ to multi-carbon products reached its maximum Faradaic efficiency (81.4%), while Cu, under the same reduction conditions, achieved only 58.3% Faradaic efficiency for multi-carbon products. Meanwhile, at 0.3 A cm⁻¹... -2 Up to 1.8A cm -2 Within the specified range, the Faraday efficiency of Cu@AIL electrocatalytic reduction of CO2 to multi-carbon products is greater than 70%.

[0054] The half-cell energy efficiency (ECE) of Cu@AIL prepared in Example 1 and Cu prepared in Comparative Example 1 is the percentage of chemical energy stored in the multi-carbon product relative to the input electrical energy. Figure 4 (c)). The half-cell energy efficiency of Cu@AIL is 0.9 A cm⁻¹. -2 At the specified current density, it can reach a maximum value of 51.1%, while Cu, as the control group, only achieves 31.6% under the same conditions. The electrochemical impedance of Cu@AIL prepared in Example 1 and Cu prepared in Comparative Example 1 were tested. The lower electrochemical impedance of Cu@AIL indicates that it has a smaller electron transfer resistance. Figure 4 (d)).

Claims

1. A method for preparing copper functionalized with an alkaline ionic liquid, comprising the following steps: S1. Borax, sodium ascorbate, ionic liquid and copper chloride are mixed and reacted. The ionic liquid is 1-aminopropyl-3-methylimidazolium bromide, 1-propyl-3-methylimidazolium bromide, or 1-propyl-3-methylimidazolium nitrate; The molar ratio of sodium ascorbate to copper chloride is 1:1~5; In the mixed aqueous solution of borax, sodium ascorbate, ionic liquid, and copper chloride, the molar concentration of borax is 0.05~0.2 mol / L, the molar concentration of sodium ascorbate is 0.02~0.2 mol / L, the molar concentration of the ionic liquid is 0.005~0.01 mol / L, and the molar concentration of copper chloride is 0.01~0.05 mol / L. The reaction temperature is 10~40 ℃ and the time is 0~2 h, but not zero; S2. The product of the reaction is obtained by electroreduction; The current density for the electroreduction is 0.1~1.0 A cm⁻¹. -2 .

2. The preparation method according to claim 1, characterized in that: The method further includes the following steps: The reaction system after the reaction is centrifuged to collect the solid product, which is then washed with water, dried, and then subjected to the electroreduction.

3. The basic ionic liquid functionalized copper prepared by the method of claim 1 or 2.

4. The application of copper functionalized with alkaline ionic liquid as described in claim 3 as an electrocatalyst in the electrocatalytic reduction of CO2 to prepare multi-carbon products.

5. A method for preparing multi-carbon products by CO2 reduction, comprising the following steps: Under mild conditions, copper functionalized with alkaline ionic liquid as described in claim 3 is dispersed in an electrolyte, and a multi-carbon product is obtained by electrocatalytic CO2 reduction reaction.

6. The method according to claim 5, characterized in that: The mild conditions refer to conditions at normal temperature and pressure; The electrolyte is an aqueous solution of potassium hydroxide or an aqueous solution of potassium bicarbonate. The current density of the electrocatalytic CO2 reduction reaction is 0.01~2.0 A cm⁻¹. -2 .

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