Amorphous copper nanosphere catalyst, ionic liquid-coated copper nanosphere catalyst and preparation method thereof

Abstract

The application discloses an amorphous copper nanosphere catalyst, an ionic liquid-coated copper nanosphere catalyst and a preparation method thereof. The preparation method of the amorphous copper nanosphere catalyst comprises the following steps: mixing copper salt crystals with deionized water to obtain a copper salt aqueous solution which is fully dissolved; adding sodium borohydride into deionized water under a nitrogen atmosphere to obtain a sodium borohydride aqueous solution; slowly adding the copper salt aqueous solution into the sodium borohydride aqueous solution to obtain a mixed solution; and performing a low-temperature water bath reaction on the mixed solution under a nitrogen atmosphere to obtain the amorphous copper nanosphere catalyst. The preparation method of the ionic liquid-coated copper nanosphere catalyst comprises the following steps: sequentially adding the amorphous copper nanosphere catalyst into water and ethanol and washing; placing the amorphous copper nanosphere catalyst obtained after the soaking and washing into a vacuum oven for drying, then adding ionic liquid; adding isopropyl alcohol to fully mix and dissolve the amorphous copper nanosphere catalyst and the ionic liquid, then heating and evaporating the isopropyl alcohol, and finally obtaining the ionic liquid-coated copper nanosphere catalyst.

Description

Technical Field

[0001] This invention belongs to the field of chemical catalysis technology for carbon dioxide reduction, and relates to an amorphous copper nanosphere catalyst, an ionic liquid-encapsulated copper nanosphere catalyst, and their preparation methods. Background Technology

[0002] Electrocatalytic carbon dioxide reduction is considered one of the most promising strategies for carbon capture and utilization. Through electroreduction, carbon dioxide can be directly converted into products such as formic acid, alcohols, and hydrocarbons. This method has the following main advantages:

[0003] (1) Electrocatalytic carbon dioxide reduction can be carried out under very mild environmental conditions, which will facilitate large-scale industrialization;

[0004] (2) The products can be effectively controlled by adjusting the characteristics of the electrolytic cell and the catalyst;

[0005] (3) The transformation process has high economic benefits and sustainability.

[0006] Due to the high chemical inertness of carbon dioxide molecules, the research on efficient and low-cost electrocatalysts has attracted widespread attention. In recent years, many researchers have applied copper catalysts to the efficient electrocatalytic reduction of carbon dioxide, and have designed many different types of copper-doped catalysts. However, the current methods for synthesizing copper nanosphere catalysts are complex and have a low success rate, which severely limits the application of this type of catalyst in the electroreduction of carbon dioxide. Summary of the Invention

[0007] The purpose of this invention is to provide an amorphous copper nanosphere catalyst, an ionic liquid-encapsulated copper nanosphere catalyst, and a method for preparing the same, in order to solve the problems of complex and low success rates in existing methods for synthesizing copper nanosphere catalysts.

[0008] The first technical solution adopted in this embodiment of the invention is: amorphous copper nanosphere catalyst, Cu 2+ and Cu + The total mass percentage is 1% to 2%, with the remainder being Cu.

[0009] Furthermore, the aforementioned amorphous copper nanosphere catalyst is used for the reduction of carbon dioxide to carbon monoxide.

[0010] The second technical solution adopted in this embodiment of the invention is: a method for preparing amorphous copper nanosphere catalysts, comprising the following steps:

[0011] Step S1: Mix copper salt crystals with deionized water to obtain a fully dissolved copper salt aqueous solution; and add sodium borohydride to deionized water under a nitrogen atmosphere to obtain a sodium borohydride aqueous solution.

[0012] Step S2: Slowly add the copper salt aqueous solution to the sodium borohydride aqueous solution to obtain a mixed solution;

[0013] Step S3: The mixture is subjected to a low-temperature water bath reaction under a nitrogen atmosphere to obtain an amorphous copper nanosphere catalyst.

[0014] Furthermore, in step S1, the molar ratio of copper salt crystals to deionized water is 1:223 to 1:333, and the copper ion concentration in the copper salt aqueous solution is 0.16 mol / L to 0.25 mol / L.

[0015] Furthermore, in step S1, the concentration of sodium borohydride in the sodium borohydride aqueous solution is between 0.9 mol / L and 1.1 mol / L.

[0016] Furthermore, in step S2, the mass ratio of copper salt to sodium borohydride in the mixture is between 1:3 and 1:5.

[0017] Furthermore, in step S3, the water bath reaction temperature is 20℃~25℃, and the reaction time is 80~100 minutes.

[0018] The third technical solution adopted in this embodiment of the invention is: a method for preparing copper nanosphere catalysts coated with ionic liquid, comprising the following steps:

[0019] Step 1: Add the amorphous copper nanosphere catalyst prepared above to water and ethanol in sequence and wash it in a centrifuge;

[0020] Step 2: After soaking, the amorphous copper nanosphere catalyst obtained is dried in a vacuum oven and then ionic liquid is added.

[0021] Step 3: Add isopropanol to fully mix and dissolve the amorphous copper nanosphere catalyst and the ionic liquid, and then heat to volatilize the isopropanol to obtain the copper nanosphere catalyst coated with ionic liquid.

[0022] Furthermore, the ionic liquid in step 2 is 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, or 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt.

[0023] In step 3, the mixture is rotary steamed at 70-80°C for 25-35 minutes.

[0024] The fourth technical solution adopted in the embodiments of the present invention is: the copper nanosphere catalyst coated with ionic liquid as prepared above is applied to the reduction of carbon dioxide to carbon monoxide.

[0025] The beneficial effects of the embodiments of the present invention are:

[0026] (1) The preparation of the ionic liquid-coated copper nanosphere catalyst is carried out under normal temperature and pressure conditions, with only two reactants. The reactants are simple and easy to control. The reaction is carried out in one step, the synthesis route is simple, easy to reproduce, and has a high success rate. The by-products are simple and easy to separate, which solves the problem that the existing methods for synthesizing copper nanosphere catalysts are complicated and have a low success rate.

[0027] (2) Compared with traditional carbon dioxide electroreduction catalyst materials, the copper nanosphere catalyst coated with ionic liquid prepared has excellent conversion efficiency of carbon dioxide reduction reaction to carbon monoxide, and can still maintain a Faraday efficiency of >90% of carbon dioxide to carbon monoxide conversion in a wide voltage range.

[0028] (3) Compared with traditional carbon dioxide electroreduction catalyst materials, the amount of metal required is very small, which can reduce the cost of industrial application and reduce environmental pollution;

[0029] (4) The prepared ionic liquid-coated copper nanosphere catalyst is uniformly dispersed on the electrode material and can be applied to the high-efficiency electrocatalytic carbon dioxide reaction, showing excellent catalytic activity. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a spherical aberration electron microscope image of the amorphous copper nanosphere catalyst prepared in Example 2.

[0032] Figure 2 This is a Faraday efficiency diagram over a wide potential range for the amorphous copper nanosphere catalyst prepared in Example 2 to reduce carbon dioxide to carbon monoxide.

[0033] Figure 3 This is a morphology image of the product when the water bath reaction for preparing amorphous copper nanosphere catalyst is carried out at a temperature of 80℃ and a time of 30 minutes.

[0034] Figure 4 This is a scanning electron microscope image of the copper nanosphere catalyst coated with ionic liquid prepared in Example 18.

[0035] Figure 5 This is a scan of the elemental fluorescence (F) in the electrocatalysis of the copper nanosphere catalyst coated with ionic liquid prepared in Example 18.

[0036] Figure 6This is a wide potential Faraday efficiency graph of the ionic liquid-coated copper nanosphere catalyst prepared in Example 18 for the electrocatalytic reduction of carbon dioxide to carbon monoxide.

[0037] Figure 7 This is a current density diagram of the electrocatalytic reduction of carbon dioxide to carbon monoxide by the ionic liquid-coated copper nanosphere catalyst prepared in Example 18.

[0038] Figure 8 This is a wide potential Faraday efficiency diagram of the electrocatalytic reduction of carbon dioxide to carbon monoxide by copper nanosphere catalyst coated with ionic liquid prepared using amorphous copper nanospheres in Example 3.

[0039] Figure 9 This is a wide potential Faraday efficiency diagram of the electrocatalytic reduction of carbon dioxide to carbon monoxide by copper nanosphere catalyst coated with ionic liquid prepared using amorphous copper nanospheres in Example 4.

[0040] Figure 10 This is a wide potential Faraday efficiency diagram of the electrocatalytic reduction of carbon dioxide to carbon monoxide by copper nanospheres coated with ionic liquid prepared using amorphous copper nanospheres in Example 5.

[0041] Figure 11 This is a wide potential Faraday efficiency diagram of the electrocatalytic reduction of carbon dioxide to carbon monoxide by copper nanosphere catalyst coated with ionic liquid prepared using amorphous copper nanospheres in Example 6.

[0042] Figure 12 This is a wide potential Faraday efficiency diagram of the electrocatalytic reduction of carbon dioxide to carbon monoxide by copper nanospheres coated with ionic liquid prepared using amorphous copper nanospheres prepared in Example 7.

[0043] Figure 13 This is a wide potential Faraday efficiency diagram of the electrocatalytic reduction of carbon dioxide to carbon monoxide by copper nanospheres coated with ionic liquid prepared using amorphous copper nanospheres in Example 8.

[0044] Figure 14 This is a Faraday efficiency diagram of pure copper nanosphere catalyst coated with ionic liquid for the electrocatalytic reduction of carbon dioxide to carbon monoxide.

[0045] Figure 15 This is a Faraday efficiency diagram of the electrocatalytic reduction of carbon dioxide to carbon monoxide by the copper nanosphere catalyst coated with ionic liquid prepared in Example 21.

[0046] Figure 16 This is a Faraday efficiency diagram of the electrocatalytic reduction of carbon dioxide to carbon monoxide by the copper nanosphere catalyst coated with ionic liquid prepared in Example 22. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] Example 1

[0049] This embodiment provides a method for preparing an amorphous copper nanosphere catalyst, including the following steps:

[0050] Step S1: Mix copper salt crystals with deionized water at a molar ratio of 1:223 to 1:333.

[0051] A fully dissolved copper salt aqueous solution was obtained, with a copper ion concentration of 0.16 mol / L to 0.25 mol / L; and sodium borohydride was added to deionized water under a nitrogen atmosphere to obtain a sodium borohydride aqueous solution with a sodium borohydride concentration of 0.9 mol / L to 1.1 mol / L.

[0052] Step S2: Under stirring conditions of 600~700 rpm, copper salt aqueous solution is slowly added dropwise to sodium borohydride aqueous solution to obtain a mixture. The mass ratio of copper salt to sodium borohydride in the mixture is between 1:3 and 1:5.

[0053] Step S3: The mixture is subjected to a water bath reaction under a nitrogen or inert gas atmosphere. The water bath reaction temperature is 20℃~25℃ and the reaction time is 80~100 minutes to obtain an amorphous copper nanosphere catalyst.

[0054] When copper salt crystals are thoroughly dissolved in deionized water at a molar ratio of 1:223 to 1:333, the resulting product is light blue, with an error within 5%. If the molar ratio of copper salt crystals to deionized water exceeds this range, the copper ion concentration is too high, resulting in uneven product formation. Conversely, if the molar ratio is below this range, the copper ion concentration is too low, leading to insufficient catalyst for the synthesis of amorphous copper nanospheres. Conducting the reaction under a nitrogen / inert gas atmosphere and at a relatively low temperature effectively prevents air from entering the reaction system, reducing the hydrolysis of sodium borohydride, ensuring the reducing properties of sodium borohydride, and preventing copper from being oxidized to form special structures that could disrupt the original structure and alter product selectivity, thus ensuring the normal progress of the reaction.

[0055] High-speed stirring may increase frictional heat, promoting the decomposition of sodium borohydride and affecting the synthesis of amorphous copper nanosphere catalysts. Low-speed stirring may lead to uneven mixing of reactants, affecting the uniform distribution of substances, resulting in a slower reaction rate and incomplete reaction.

[0056] Example 2

[0057] This embodiment provides a method for preparing an amorphous copper nanosphere catalyst, including the following steps:

[0058] Step S1: Mix copper salt crystals with deionized water at a molar ratio of 1:280 and sonicate to obtain a fully dissolved copper salt aqueous solution with a copper ion concentration of 0.2 mol / L; and add sodium borohydride to deionized water under a nitrogen atmosphere to obtain a sodium borohydride aqueous solution with a sodium borohydride concentration of 1 mol / L.

[0059] Step S2: Under magnetic stirring at 600 rpm, copper salt aqueous solution is slowly added dropwise to sodium borohydride aqueous solution to obtain a mixture. The mass ratio of copper salt to sodium borohydride in the mixture is 1:4.

[0060] Step S3: The mixture is reacted in a water bath under a nitrogen atmosphere at 20°C for 90 minutes to obtain the following... Figure 1 The amorphous copper nanosphere catalyst shown in this embodiment exhibits a Faraday efficiency of [missing information - likely a specific efficiency value] for the carbon dioxide reduction reaction to produce carbon monoxide. Figure 2 As shown, the optimal Faraday efficiency reaches 80.

[0061] Example 3

[0062] The difference between this embodiment and Example 2 is that the molar ratio of copper salt crystals to deionized water is 1:223, the copper ion concentration in the copper salt aqueous solution is 0.25 mol / L, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for carbon dioxide reduction reaction to produce carbon monoxide is 76.

[0063] Example 4

[0064] The difference between this embodiment and Example 2 is that the molar ratio of copper salt crystals to deionized water is 1:300, the copper ion concentration in the copper salt aqueous solution is 0.185 mol / L, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for carbon dioxide reduction reaction to produce carbon monoxide is 77.

[0065] Example 5

[0066] The difference between this embodiment and Example 2 is that the molar ratio of copper salt crystals to deionized water is 1:320, the copper ion concentration in the copper salt aqueous solution is 0.176 mol / L, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for carbon dioxide reduction reaction to produce carbon monoxide is 76.

[0067] Example 6

[0068] The difference between this embodiment and Example 2 is that the molar ratio of copper salt crystals to deionized water is 1:200, the copper ion concentration in the copper salt aqueous solution is 0.278 mol / L, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for carbon dioxide reduction reaction to produce carbon monoxide is 72.

[0069] Example 7

[0070] The difference between this embodiment and Example 2 is that the molar ratio of copper salt crystals to deionized water is 1:380, the copper ion concentration in the copper salt aqueous solution is 0.146 mol / L, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for carbon dioxide reduction reaction to produce carbon monoxide is 70.

[0071] Example 8

[0072] The difference between this embodiment and Example 2 is that the water bath reaction temperature is 60°C and the time is 90 minutes, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for carbon dioxide reduction reaction to produce carbon monoxide is 71.

[0073] Example 9

[0074] The difference between this embodiment and Example 2 is that the water bath reaction temperature is 80°C and the time is 30 minutes, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for carbon dioxide reduction reaction to produce carbon monoxide is 68%.

[0075] Example 10

[0076] The difference between this embodiment and Example 2 is that the mass ratio of copper salt to sodium borohydride in the mixture in step S2 is 1:4.8, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for carbon dioxide reduction reaction to produce carbon monoxide is 77.

[0077] Example 11

[0078] The difference between this embodiment and Example 2 is that the mass ratio of copper salt to sodium borohydride in the mixture in step S2 is 1:5.4, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for carbon dioxide reduction reaction to produce carbon monoxide is 70.

[0079] Example 12

[0080] The difference between this embodiment and Embodiment 2 is that the mass ratio of copper salt and sodium borohydride in the mixture in step S2 is 1:5, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for carbon dioxide reduction reaction to produce carbon monoxide is 73.

[0081] Example 13

[0082] The difference between this embodiment and Example 2 is that the mass ratio of copper salt to sodium borohydride in the mixture in step S2 is 1:2.5, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for carbon dioxide reduction reaction to produce carbon monoxide is 69.

[0083] Example 14

[0084] The difference between this embodiment and Example 2 is that the concentration of sodium borohydride in the sodium borohydride aqueous solution is 0.9 mol / L, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for the carbon dioxide reduction reaction to produce carbon monoxide is 75.

[0085] Example 15

[0086] The difference between this embodiment and Example 2 is that the concentration of sodium borohydride in the sodium borohydride aqueous solution is 1.1 mol / L, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for the carbon dioxide reduction reaction to produce carbon monoxide is 75.

[0087] Example 16

[0088] The difference between this embodiment and Example 2 is that the concentration of sodium borohydride in the sodium borohydride aqueous solution is 0.6 mol / L, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for the carbon dioxide reduction reaction to produce carbon monoxide is 69.

[0089] Example 17

[0090] The difference between this embodiment and Example 2 is that the concentration of sodium borohydride in the sodium borohydride aqueous solution is 1.5 mol / L, and the optimal Faraday efficiency of the prepared amorphous copper nanosphere catalyst for the carbon dioxide reduction reaction to produce carbon monoxide is 72.

[0091] The high temperature of the water bath reaction may cause copper to oxidize and may also lead to the formation of some special structures, thereby destroying the original structure and changing the selectivity of the product. Figure 3 The image shows the morphology of the product prepared by a water bath reaction at 80℃ for 30 minutes. It can be seen that it is not the same as the desired amorphous copper nanosphere catalyst. Therefore, excessively high temperatures are not conducive to the formation of amorphous copper nanosphere catalysts.

[0092] Example 18

[0093] This embodiment provides a method for preparing an ionic liquid-coated copper nanosphere catalyst, comprising the following steps:

[0094] Step 1: The amorphous copper nanosphere catalyst prepared in Example 2 was added to water and ethanol in sequence and then washed in a centrifuge. Water was added 3 times and ethanol was added once.

[0095] Step 2: Place the amorphous copper nanosphere catalyst obtained after immersion into a vacuum oven, dry it at 60°C, and then add 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt as an ionic liquid. The mass ratio of amorphous copper nanocatalyst to ionic liquid is 10:1.

[0096] Step 3: Weigh 0.5g of the amorphous copper nanosphere catalyst after adding the ionic liquid, then add 40ml of isopropanol. First add a certain amount of ionic liquid, then add the isopropanol to fully dissolve the catalyst. Rotate the solution at 70℃ for 25-35 minutes, specifically 30 minutes. The isopropanol will evaporate during the rotational evaporation process, yielding the following... Figure 4 The image shows a copper nanosphere catalyst coated with an ionic liquid. Further testing and analysis revealed that the ionic liquid cannot be detected under an electron microscope; only elemental scanning can determine whether the ionic liquid is coated on the amorphous copper nanosphere catalyst. Figure 5 The image shown is a fluorescence scan of the fluorine (F) element in the ionic liquid-coated copper nanosphere catalyst prepared in this embodiment. Since the amorphous copper nanospheres do not contain F during preparation, and F only exists in the ionic liquid, the fluorescence intensity is lower than that of the ionic liquid. Figure 5 This demonstrates the successful preparation of copper nanosphere catalysts coated with ionic liquids.

[0097] The performance of the ionic liquid-coated copper nanosphere catalyst prepared in Example 18 for the electrocatalytic reduction of carbon dioxide to carbon monoxide was tested as follows:

[0098] The copper nanosphere catalyst coated with ionic liquid and supported on a carbon paper electrode was tested using a three-electrode H-type electrolytic cell. The carbon paper electrode was used as the working electrode, the counter electrode was an iron sheet, the reference electrode was an Ag / AgCl electrode, and the electrolyte was a 0.5 M KHCO3 aqueous solution. The test voltage range was -0.65 V to 1.05 V. vs. RHE.

[0099] like Figure 6 As shown, the test results indicate that the ionic liquid-coated copper nanosphere catalyst supported on a carbon paper electrode at -0.88 V on pure carbon paper... vs. The Faraday efficiency for carbon monoxide production at the RHE potential is 97.28%, and it maintains a carbon monoxide Faraday efficiency of >90% over a wide range of test voltages. For example... Figure 7 As shown, the test results indicate that up to >20 mA / cm² can be generated even in an H-type electrolytic cell. 2 The electrochemical carbon dioxide reduction current density can meet industrial needs.

[0100] Meanwhile, the amorphous copper nanosphere catalyst prepared in step 1 of Example 18 was replaced with the amorphous copper nanosphere catalyst prepared in Examples 3-8, respectively. The Faraday efficiency diagram of the ionic liquid-coated copper nanosphere catalyst for the electrocatalytic reduction of carbon dioxide to carbon monoxide is shown in the figure. Figures 8-13 It can be seen that, compared with the ideal molar ratio in Example 2, when the molar ratio of copper salt crystals to deionized water is 1:380, the Faraday efficiency of electrocatalytic carbon dioxide reduction of carbon monoxide is significantly reduced; when the water bath reaction temperature is 60°C, the Faraday efficiency of electrocatalytic carbon dioxide reduction of carbon monoxide is significantly reduced compared with the low temperature water bath.

[0101] Measurements showed that the mass percentage of Cu in the amorphous copper nanosphere catalysts prepared in Examples 2-5 of this invention was over 97%, and Cu... 2+ and Cu + The mass percentage of each component is 1% to 2%, and the copper nanosphere catalyst coated with ionic liquid prepared using this amorphous copper nanosphere catalyst has better performance. Figure 14 The Faraday efficiency diagram of the pure copper nanosphere catalyst coated with ionic liquid for the electrocatalytic reduction of carbon dioxide to carbon monoxide shows that, compared with the amorphous copper nanospheres containing copper ions in Example 18, the catalyst coated with ionic liquid under pure copper nanospheres has poorer performance, further highlighting the role of low-temperature water bath reaction in the preparation of amorphous copper nanospheres in the embodiments of the present invention.

[0102] Example 19

[0103] This embodiment provides a method for preparing an ionic liquid-coated copper nanosphere catalyst, comprising the following steps:

[0104] Step 1: The amorphous copper nanosphere catalyst prepared in Example 2 was added to water and ethanol in sequence and then washed in a centrifuge. Water was added 4 times and ethanol was added once.

[0105] Step 2: Place the catalyst obtained after soaking into a vacuum oven and dry it at 50°C. Then add 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt as an ionic liquid. The mass ratio of amorphous copper nanocatalyst to ionic liquid is 5:1.

[0106] Step 3: Weigh 0.5g of the amorphous copper nanosphere catalyst after adding ionic liquid, add 40ml of isopropanol, and rotary evaporate at 75℃ for 30 minutes to obtain the copper nanosphere catalyst coated with ionic liquid.

[0107] The morphology of the ionic liquid-coated copper nanosphere catalyst prepared in this embodiment is similar to that in Example 18, and its performance indicators are as follows: the optimal Faraday efficiency of the synthesized ionic liquid-coated copper nanosphere catalyst for catalyzing the reduction of carbon dioxide to produce carbon monoxide is 94.8%, and the current density can reach 23 mA / cm². 2 It exhibits excellent selectivity in the electrochemical reduction of carbon dioxide to carbon monoxide.

[0108] Example 20

[0109] This embodiment provides a method for preparing an ionic liquid-coated copper nanosphere catalyst, comprising the following steps:

[0110] Step 1: The amorphous copper nanosphere catalyst prepared in Example 2 was added to water and ethanol in sequence and then washed in a centrifuge. Water was added 5 times and ethanol was added 2 times.

[0111] Step 2: Place the catalyst obtained after soaking into a vacuum oven and dry it at 55°C. Then add 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt as an ionic liquid. The mass ratio of amorphous copper nanocatalyst to ionic liquid is 15:1.

[0112] Step 3: Weigh 0.5g of amorphous copper nanosphere catalyst and add 40ml of isopropanol. Rotate the solution at 80℃ for 30 minutes to obtain copper nanosphere catalyst coated with ionic liquid.

[0113] The morphology of the ionic liquid-coated copper nanosphere catalyst obtained in Example 6 is similar to that in Example 18, and its performance indicators are as follows: The synthesized ionic liquid-coated copper nanosphere catalyst has a clear single-atom structure similar to that in Example 18, and the optimal Faraday efficiency for producing carbon monoxide is 92.9%, exhibiting excellent selectivity for the electrochemical reduction of carbon dioxide to carbon monoxide.

[0114] Too low a rotary evaporation temperature will result in incomplete volatilization of isopropanol, leading to the failure of the synthesis of copper nanosphere catalysts coated with ionic liquids; too high a rotary evaporation temperature may result in the loss of volatile components in the mixture, affecting the product performance.

[0115] Example 21

[0116] The difference between this embodiment and Example 18 is that the ionic liquid used is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt. The Faraday efficiency of the copper nanosphere catalyst coated with the prepared ionic liquid for the electrocatalytic reduction of carbon dioxide to carbon monoxide is shown in [reference needed]. Figure 15 .

[0117] Example 22

[0118] The difference between this embodiment and Example 18 is that the ionic liquid used is 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt. The Faraday efficiency of the copper nanosphere catalyst coated with the prepared ionic liquid for the electrocatalytic reduction of carbon dioxide to carbon monoxide is shown in [reference needed]. Figure 16 .

[0119] based on Figure 6 as well as Figures 15-16 It can be seen that the electrocatalytic performance of copper nanosphere catalysts coated with ionic liquids prepared using different ionic liquids for the reduction of carbon dioxide to carbon monoxide varies to some extent. Compared with 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt has better performance.

[0120] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A process for the preparation of an ionic liquid-coated copper nanospheres catalyst, characterized in that, Includes the following steps: Step 1: Add the amorphous copper nanosphere catalyst to water and ethanol in sequence and wash it in a centrifuge; The amorphous copper nanosphere catalyst, Cu 2+ and Cu + The mass ratio of Cu, Cu and Cu is 1% to 2%, and the rest is Cu; the preparation of the amorphous copper nanosphere catalyst includes the following steps: Step S1-1: Mix copper salt crystals with deionized water to obtain a fully dissolved copper salt aqueous solution; and add sodium borohydride to deionized water under a nitrogen atmosphere to obtain a sodium borohydride aqueous solution. Step S1-2: Slowly add the copper salt aqueous solution to the sodium borohydride aqueous solution to obtain a mixed solution; Steps S1-3: The mixture is subjected to a low-temperature water bath reaction under a nitrogen atmosphere to obtain an amorphous copper nanosphere catalyst; Step 2: After immersion and washing, the amorphous copper nanosphere catalyst is dried in a vacuum oven and then an ionic liquid is added; the ionic liquid in Step 2 is 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt or 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt; Step 3: Add isopropanol to fully mix and dissolve the amorphous copper nanosphere catalyst and the ionic liquid, and then heat to volatilize the isopropanol to obtain the copper nanosphere catalyst coated with ionic liquid; in step 3, rotary evaporation is carried out at 70~80℃ for 25~35 minutes.

2. The method of claim 1, wherein the ionic liquid-coated copper nanospheres catalyst is prepared by the steps of: (a) preparing a copper nanosphere catalyst; (b) preparing an ionic liquid; (c) mixing the copper nanosphere catalyst and the ionic liquid to form a mixture; and (d) drying the mixture. In step S1-1, the molar ratio of copper salt crystals to deionized water is 1:223 to 1:333, and the concentration of copper ions in the copper salt aqueous solution is 0.16 mol / L to 0.25 mol / L.

3. The method of claim 1, wherein the ionic liquid-coated copper nanospheres catalyst is prepared by the steps of: (a) preparing a copper nanosphere catalyst; (b) preparing an ionic liquid; (c) mixing the copper nanosphere catalyst and the ionic liquid to form a mixture; and (d) drying the mixture. In step S1-1, the concentration of sodium borohydride in the sodium borohydride aqueous solution is between 0.9 mol / L and 1.1 mol / L.

4. The method of claim 1, wherein the ionic liquid-coated copper nanospheres catalyst is prepared by the steps of: In steps S1-2, the mass ratio of copper salt to sodium borohydride in the mixture is between 1:3 and 1:

5.

5. The method of claim 1, wherein the ionic liquid-coated copper nanospheres catalyst is prepared by the steps of: (a) preparing a copper nanosphere catalyst; (b) preparing an ionic liquid; (c) mixing the copper nanosphere catalyst and the ionic liquid to form a mixture; and (d) drying the mixture. In steps S1-3, the water bath reaction temperature is 20℃~25℃, and the reaction time is 80~100 minutes.

6. The ionic liquid-coated copper nanospheres catalyst prepared according to claim 1, characterized in that, It is used to reduce carbon dioxide to produce carbon monoxide.

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