Preparation method and application of cuprous oxide hollow nano-microspheres

Abstract

The invention discloses a preparation method and application of cuprous oxide hollow nano microspheres, and belongs to the technical field of nano material preparation. The cuprous oxide hollow nano-microspheres are assembled by small cuprous oxide nano-particles induced by a soft template method, and are used for electrocatalytic carbon dioxide reduction reaction. The method comprises the following steps: dissolving bis (2-ethylhexyl) sodium sulfosuccinate and sodium dodecyl benzene sulfonate in water to construct anion vesicles, adding a 4-ethylpyridine complex of copper, and then adding a reducing agent to generate cuprous oxide. The material is a hollow nanosphere assembled by extremely small nanoparticles, the specific surface area of the material can be increased, more active sites can be exposed, and the limiting effect of the hollow structure also enables the material to have relatively excellent performance in preparation of a multi-carbon product by electrocatalytic reduction of carbon dioxide. In addition, due to the simple preparation method and the special structure of the material, the material can also have a relatively large application prospect in other fields.

Description

Technical Field

[0001] The invention belongs to nanomaterials with multiple potential application values, and specifically relates to a preparation method and application of cuprous oxide hollow nano-microspheres, and is applied to electrocatalytic carbon dioxide reduction. Background Art

[0002] It is well known that the size, morphology and structure of nanomaterials significantly affect their physical and chemical properties, and the resulting enhanced performance and potential application value have attracted increasing attention, especially in the fields of drug delivery, artificial cells, lightweight fillers, catalysis and chemical storage, hollow structured nanomaterials have great application potential. In the past few decades, people have conducted extensive research on the controlled synthesis of nanocrystals, and various methods have been developed to achieve this special nanostructure. For example, template synthesis is a typical and effective approach, and people have used hard templates or soft templates to synthesize a variety of hollow structured nanomaterials. However, the existing mature template synthesis methods also have many problems, such as most methods have cumbersome steps or use a large amount of template agents, and the electrostatic interaction between metal ions and surfactants has also hindered the application of soft template methods to prepare hollow metal oxides. The prepared hollow spherical shells are also generally smooth and uniform, which can further increase the active sites.

[0003] With the acceleration of global industrialization and the continuous increase in the concentration of carbon dioxide in the atmosphere, people are also committed to the reuse of carbon dioxide. Among them, electrocatalytic carbon dioxide reduction technology has attracted widespread attention due to its many advantages. Studies have found that copper-based catalysts can promote the production of a variety of hydrocarbons and oxygen-containing compounds such as alcohols, and catalysts with hollow structures can improve their performance by enriching reaction intermediates. However, current copper-based catalysts still have many problems such as low selectivity and low current density. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing cuprous oxide hollow microsphere nanomaterials that may have multiple application values, and to use them for electrocatalytic carbon dioxide reduction reaction, in an attempt to solve the problems of low catalytic activity in the prior art.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: A method for preparing cuprous oxide hollow nano-microspheres comprises the following steps: S1. Add sodium bis(2-ethylhexyl)sulfosuccinate and sodium dodecylbenzenesulfonate into deionized water and stir until dissolved; the molar ratio of sodium bis(2-ethylhexyl)sulfosuccinate to sodium dodecylbenzenesulfonate is 2.8:2.4; the concentration of sodium bis(2-ethylhexyl)sulfosuccinate is 6.22 – 12.44 g / L; S2. Add 4-ethylpyridine to the copper acetate solution to form a dark blue solution; the concentrations of the copper ions and 4-ethylpyridine are equal; S3, adding the solution in step S2 to the solution in step S1, and continuing stirring; wherein the molar ratio of copper ion to sodium bis(2-ethylhexyl)sulfosuccinate is (0.4-0.6):(1.4-2.8); S4, dissolving ascorbic acid and sodium hydroxide in ionized water to prepare a reducing agent solution; wherein the molar ratio of ascorbic acid to copper ions is (1-5):1, and the molar ratio of sodium hydroxide to copper ions is (0-30):1; S5, adding the solution prepared in step S4 to the mixed solution obtained in step S3, and reacting for 10 min-30 min; S6. After the reaction is completed, centrifugation, washing and drying are performed to obtain cuprous oxide hollow nano-microspheres.

[0006] In step S2, the concentrations of copper ions and 4-ethylpyridine are both 0.1 mol / L.

[0007] The ascorbic acid concentration in the reducing agent solution is 0.3 mol / L, and the sodium hydroxide concentration is 1.2 mol / L.

[0008] A cuprous oxide hollow nano-microsphere is prepared by adopting the method.

[0009] The cuprous oxide hollow nano-microspheres are used in electrocatalytic carbon dioxide reduction reactions.

[0010] An electrode is prepared by using the above-mentioned cuprous oxide hollow nano-microspheres.

[0011] A method for preparing an electrode, wherein the cuprous oxide hollow nanospheres are loaded on carbon paper by a drop coating method, and the loading amount is 0.2-1 mg / cm 2 .

[0012] The electrode is used in an electrocatalytic carbon dioxide reduction reaction.

[0013] Specifically, a method for preparing cuprous oxide hollow nanospheres comprises the following steps: (S1) Take 100 mL of deionized water in a round-bottom flask, add 0.622-1.244 g of sodium bis(2-ethylhexyl)sulfosuccinate and 0.418-0.836 g of sodium dodecylbenzenesulfonate, and stir thoroughly in an oil bath at 30-50 °C until dissolved.

[0014] (S2) Take 0.2 g of copper acetate and fully dissolve it in 10 mL of deionized water. Then add 115 μL of 4-ethylpyridine to form a dark blue solution.

[0015] (S3) Take 6 mL of the solution in S2 and add it to the solution in S1. Continue stirring and stabilize for 0.5 h.

[0016] (S4) Take 0.106-0.540 g of ascorbic acid and 0-0.480 g of sodium hydroxide in a beaker and dissolve them with 10 mL of deionized water.

[0017] (S5) The solution prepared in S4 is added to the mixed solution obtained in S3 at an appropriate rate and the reaction is continued for 10 minutes.

[0018] (S6) The yellow turbid liquid obtained in S5 is centrifuged and washed with deionized water for multiple times, and finally washed once with ethanol, and then dried in a vacuum drying oven at 50°C for later use.

[0019] The control group was the material prepared without adding any surfactant.

[0020] The nano material is loaded on carbon paper by a drop coating method and applied to an electrocatalytic carbon dioxide reduction reaction.

[0021] Compared with the prior art, the present invention has the following advantages: Cuprous oxide hollow nanospheres are assembled from small cuprous oxide nanoparticles induced by an optimized soft template method and used for electrocatalytic carbon dioxide reduction reaction. The method is to dissolve sodium bis(2-ethylhexyl)sulfosuccinate and sodium dodecylbenzenesulfonate in water to construct anionic vesicles, add copper 4-ethylpyridine complex, and add a reducing agent to generate cuprous oxide.

[0022] (1) The hollow structure nanospheres are assembled from extremely small nanoparticles, which is beneficial to increase the specific surface area of ​​the material and expose more active sites. Compared with the uniform solid spherical shells in other hollow nanomaterials, the present invention can expose more active sites.

[0023] (2) Compared with other methods, the optimized method uses less surfactant (such as the CTAB method), but can still keep the material in good morphology, uniform size, and obvious hollow structure.

[0024] (3) The hollow structure helps to enrich the intermediates in the electrocatalytic carbon dioxide reduction reaction, thereby promoting the production of multi-carbon products such as ethylene and ethanol. The confinement effect of the hollow structure also makes it show excellent performance in the research of electrocatalytic carbon dioxide reduction to prepare multi-carbon products.

[0025] In summary, copper-based nanomaterials with hollow structures not only have a larger specific surface area and more active sites, but can also effectively enrich reaction intermediates through spatial confinement effects, promote the occurrence of CC coupling reactions, and promote the production of multi-carbon products such as ethylene and ethanol. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the process of Example 1 of the present invention.

[0027] Figure 2 The scanning electron microscope pictures of Examples 1-6 and Comparative Examples 1-2 of the present invention are shown.

[0028] Figure 3 1 and 2 are X-ray diffraction diagrams of Example 1 of the present invention and Comparative Example 1.

[0029] Figure 4 The transmission electron microscope pictures of Example 1 and Comparative Examples 1-2 of the present invention are shown.

[0030] Figure 5 This is a Faraday efficiency diagram of the catalytic performance of the electrocatalytic carbon dioxide reduction reaction according to Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The present invention is further described below with reference to the accompanying drawings and examples. The embodiments of the present invention include but are not limited to implementation cases.

[0032] A method for preparing cuprous oxide hollow nanospheres is provided, wherein the hollow nanospheres are assembled by inducing small cuprous oxide nanoparticles through an optimized soft template method, and the method comprises the following steps: (S1) Take 100 mL of deionized water in a round-bottom flask, add 0.622 - 1.244 g of sodium bis(2-ethylhexyl)sulfosuccinate and 0.418 - 0.836 g of sodium dodecylbenzenesulfonate, and stir thoroughly in an oil bath at 30 - 50 °C until dissolved.

[0033] (S2) 0.2 g of copper acetate was fully dissolved in 10 mL of deionized water, and then 115 μL of 4-ethylpyridine was added to form a dark blue solution.

[0034] (S3) Take 6 mL of the solution in S2 and add it to the solution in S1. Continue stirring and stabilize for 0.5 h.

[0035] (S4) Take 0.106 - 0.540 g of ascorbic acid and 0 - 0.480 g of sodium hydroxide in a beaker and dissolve them in 10 mL of deionized water.

[0036] (S5) The solution prepared in S4 is added to the mixed solution obtained in S3 at an appropriate rate and the reaction is continued for 10 minutes.

[0037] (S6) The yellow turbid liquid obtained in S5 is centrifuged and washed with deionized water for multiple times, and finally washed once with ethanol, and then dried in a vacuum drying oven at 50°C for later use.

[0038] The control group was the material prepared without adding any surfactant.

[0039] The nano material is loaded on carbon paper by a drop coating method and applied to an electrocatalytic carbon dioxide reduction reaction.

[0040] The specific implementation cases are as follows: Example 1

[0041] A method for preparing cuprous oxide hollow nanospheres is provided, wherein the hollow nanospheres are assembled by inducing small cuprous oxide nanoparticles through an optimized soft template method, and the method comprises the following steps: Take 100mL of deionized water in a round-bottom flask, add 0.622g of sodium bis(2-ethylhexyl)sulfosuccinate and 0.418g of sodium dodecylbenzenesulfonate, and stir thoroughly in a 30°C oil bath until dissolved. Take 0.2g of copper acetate and fully dissolve it in 10mL of deionized water, then add 115μL of 4-ethylpyridine to form a dark blue solution. Take 6mL of the above solution and add it to the surfactant solution, and continue to stir and stabilize for 0.5h. Take 0.54g of ascorbic acid and 0.48g of sodium hydroxide in a beaker and dissolve them in 10mL of deionized water as a reducing agent solution. After adding the reducing agent solution to the mixed solution of surfactant and copper ions and reacting for 10min, the resulting yellow turbid liquid is centrifuged and washed with deionized water several times, and finally washed twice with ethanol and placed in a vacuum drying oven at 50°C for use. Example 2

[0042] Take 100mL of deionized water in a round-bottom flask, add 1.244g of sodium bis(2-ethylhexyl)sulfosuccinate and 0.836g of sodium dodecylbenzenesulfonate, and stir thoroughly in a 30°C oil bath until dissolved. Take 0.2g of copper acetate and fully dissolve it in 10mL of deionized water, then add 115μL of 4-ethylpyridine to form a dark blue solution. Take 6mL of the above solution and add it to the surfactant solution, and continue to stir and stabilize for 0.5h. Take 0.54g of ascorbic acid and 0.48g of sodium hydroxide in a beaker and dissolve them in 10mL of deionized water as a reducing agent solution. After adding the reducing agent solution to the mixed solution of surfactant and copper ions and reacting for 10min, the resulting yellow turbid liquid is centrifuged and washed with deionized water several times, and finally washed twice with ethanol and placed in a vacuum drying oven at 50°C for use. Example 3

[0043] Take 100mL of deionized water in a round-bottom flask, add 1.244g of sodium bis(2-ethylhexyl)sulfosuccinate and 0.836g of sodium dodecylbenzenesulfonate, and stir thoroughly in a 30°C oil bath until dissolved. Take 0.2g of copper acetate and fully dissolve it in 10mL of deionized water, then add 115μL of 4-ethylpyridine to form a dark blue solution. Take 6mL of the above solution and add it to the surfactant solution, and continue to stir and stabilize for 0.5h. Take 0.54g of ascorbic acid and 0.48g of sodium hydroxide in a beaker and dissolve them in 10mL of deionized water as a reducing agent solution. After adding the reducing agent solution to the mixed solution of surfactant and copper ions and reacting for 30min, the resulting yellow turbid liquid is centrifuged and washed with deionized water for several times, and finally washed twice with ethanol and placed in a vacuum drying oven at 50°C for use. Example 4

[0044] Take 100mL of deionized water in a round-bottom flask, add 1.244g of sodium bis(2-ethylhexyl)sulfosuccinate and 0.836g of sodium dodecylbenzenesulfonate, and stir thoroughly in a 50℃ oil bath until dissolved. Take 0.2g of copper acetate and fully dissolve it in 10mL of deionized water, then add 115μL of 4-ethylpyridine to form a dark blue solution. Take 6mL of the above solution and add it to the surfactant solution, and continue to stir and stabilize for 0.5h. Take 0.54g of ascorbic acid and 0.48g of sodium hydroxide in a beaker and dissolve them in 10mL of deionized water as a reducing agent solution. After adding the reducing agent solution to the mixed solution of surfactant and copper ions and reacting for 10min, the resulting yellow turbid liquid is centrifuged and washed with deionized water for several times, and finally washed twice with ethanol and placed in a vacuum drying oven at 50℃ for use. Example 5

[0045] Take 100mL of deionized water in a round-bottom flask, add 1.244g of sodium bis(2-ethylhexyl)sulfosuccinate and 0.836g of sodium dodecylbenzenesulfonate, and stir thoroughly in a 30°C oil bath until dissolved. Take 0.2g of copper acetate and fully dissolve it in 10mL of deionized water, then add 115μL of 4-ethylpyridine to form a dark blue solution. Take 6mL of the above solution and add it to the surfactant solution, and continue to stir and stabilize for 0.5h. Take 0.106g of ascorbic acid in a beaker and dissolve it in 10mL of deionized water as a reducing agent solution. After adding the reducing agent solution to the mixed solution of surfactant and copper ions and reacting for 30min, the resulting yellow turbid liquid is centrifuged and washed with deionized water several times, and finally washed twice with ethanol and placed in a vacuum drying oven at 50°C for use. Example 6

[0046] Take 100mL of deionized water in a round-bottom flask, add 1.244g of sodium bis(2-ethylhexyl)sulfosuccinate and 0.836g of sodium dodecylbenzenesulfonate, and stir thoroughly in a 30°C oil bath until dissolved. Take 0.2g of copper acetate and fully dissolve it in 10mL of deionized water, then add 115μL of 4-ethylpyridine to form a dark blue solution. Take 4mL of the above solution and add it to the surfactant solution, and continue to stir and stabilize for 0.5h. Take 0.070g of ascorbic acid in a beaker and dissolve it in 10mL of deionized water as a reducing agent solution. After adding the reducing agent solution to the mixed solution of surfactant and copper ions and reacting for 30min, the resulting yellow turbid liquid is centrifuged and washed with deionized water several times, and finally washed twice with ethanol and placed in a vacuum drying oven at 50°C for use.

[0047] Comparative Example 1

[0048] Take 0.2g of copper acetate and fully dissolve it in 10mL of deionized water, then add 115μL of 4-ethylpyridine to form a dark blue solution. Take 6mL of the above solution and add it to a round-bottom flask and add 100mL of deionized water, stir and stabilize for 0.5h in a 30℃ oil bath. Take 0.54g of ascorbic acid and 0.48g of sodium hydroxide in a beaker and dissolve them in 10mL of deionized water as a reducing agent solution. After adding the reducing agent solution to the solution of the copper complex and reacting for 10min, the resulting yellow turbid liquid is centrifuged and washed with deionized water several times, and finally washed twice with ethanol and dried in a vacuum drying oven at 50℃ for use.

[0049] Comparative Example 2

[0050] Take 0.2g of copper acetate and fully dissolve it in 10mL of deionized water, then add 115μL of 4-ethylpyridine to form a dark blue solution. Take 6mL of the above solution and add it to a round-bottom flask and add 100mL of deionized water, stir and stabilize for 0.5h in a 30℃ oil bath. Take 0.106g of ascorbic acid in a beaker and dissolve it in 10mL of deionized water as a reducing agent solution. After adding the reducing agent solution to the solution of the copper complex and reacting for 10min, the resulting yellow turbid liquid is centrifuged and washed with deionized water several times, and finally washed twice with ethanol and dried in a vacuum drying oven at 50℃ for use.

[0051] Figure 2The following are scanning electron microscope photos of the materials obtained from Example 1, Example 2, Example 3, Example 4, Example 5, Example 6 of the present invention and Comparative Example 1 and Comparative Example 2. It can be seen that the nanomaterial obtained in Example 1 (Figure a) has good morphology, uniform size, and a hollow structure can be observed. When the surfactant concentration is doubled (Example 2 (Figure b), the material morphology is still good. When the reaction time is extended to 30 minutes (Example 3, Figure c), some nanospheres are broken and turned into dispersed nanoparticles again, which is similar to the morphology of the material obtained when the reaction time is unchanged but the temperature is raised to 50°C (Example 4, Figure d). It can be inferred that the assembly of anionic vesicles will be destroyed after the reaction reaches a certain extent. When the reducing agent solution is changed (Example 5, Figure e), crystal nucleation is hindered, so that the nanospheres are not assembled from nanoparticles, the microsphere morphology is irregular, and the morphology remains basically unchanged when the copper ion concentration is changed (Example 6, Figure f). When no surfactant is added (Comparative Example 1, Figure g), the nanoparticles will not assemble into hollow microspheres, and irregular aggregation will occur. When no surfactant is added and the reducing agent solution is changed (Comparative Example 2, Figure h), the nanomaterial presents a regular solid spherical structure.

[0052] Figure 3 The X-ray diffraction diagrams of the materials obtained in Example 1 and Comparative Example 1 of the present invention show that both materials are cuprous oxide materials with obvious lattices. The material in Comparative Example 1 has a lattice peak of cupric oxide with extremely low intensity because of its extremely small size and dispersion and its surface is more susceptible to oxygen oxidation.

[0053] Figure 4 The transmission electron microscope images of the nanomaterials obtained in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention show that the extremely small nanoparticles are assembled into hollow nanospheres under the action of the surfactant (Figure a), and the dispersed nanoparticles will aggregate irregularly without the surfactant (Figure b). If the amount of the reducing agent is changed and reduced, the spherical nanomaterial shows an obvious solid structure (Figure c).

[0054] Example 1 was used for the application study of electrocatalytic carbon dioxide reduction and loaded on carbon paper by a common drop coating method with a loading amount of 0.4 mg / cm 2 The catalytic performance of the material was tested on an electrochemical workstation CHI1140E, and the product was analyzed by gas chromatography and liquid chromatography. Figure 5 It can be seen that the Faraday efficiency of multi-carbon products can be maintained above 50% in a wide range, and the yield of single-carbon products such as carbon monoxide is low, which benefits from the enrichment of reaction intermediates by the hollow structure and promotes the synthesis of multi-carbon products. The high amount of by-product hydrogen may be due to the adsorption of a small amount of 4-ethylpyridine or surfactant molecules on the surface of the material, which enhances its hydrogen evolution ability.

[0055] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any changes made by adopting the design principles of the present invention and performing non-creative work on this basis should fall within the protection scope of the present invention.

Claims

1. A method for preparing cuprous oxide hollow nanospheres, characterized in that: The steps include: S1. Add sodium bis(2-ethylhexyl)sulfosuccinate and sodium dodecylbenzenesulfonate into deionized water and stir until dissolved; the molar ratio of sodium bis(2-ethylhexyl)sulfosuccinate to sodium dodecylbenzenesulfonate is 2.8:2.4; the concentration of sodium bis(2-ethylhexyl)sulfosuccinate is 6.22-12.44 g / L; S2, adding 4-ethylpyridine to the copper acetate solution to form a dark blue mixed solution; the concentrations of copper ions and 4-ethylpyridine in the mixed solution are equal; S3, adding the solution in step S2 to the solution in step S1, and continuing stirring; wherein the molar ratio of copper ion to sodium bis(2-ethylhexyl)sulfosuccinate is (0.4-0.6):(1.4-2.8); S4, dissolving ascorbic acid and sodium hydroxide in ionized water to prepare a reducing agent solution; wherein the molar ratio of ascorbic acid to copper ions is (1-5):1, and the molar ratio of sodium hydroxide to copper ions is (20-30):1; S5, adding the solution prepared in step S4 to the mixed solution obtained in step S3, and reacting for 10 min-30 min; S6. After the reaction is completed, centrifugation, washing and drying are performed to obtain cuprous oxide hollow nano-microspheres.

2. The method for preparing cuprous oxide hollow nanospheres according to claim 1, characterized in that: In step S2, the concentrations of copper ions and 4-ethylpyridine are both 0.1 mol / L.

3. The method for preparing cuprous oxide hollow nanospheres according to claim 1, characterized in that: The ascorbic acid concentration in the reducing agent solution is 0.3 mol / L, and the sodium hydroxide concentration is 1.2 mol / L.

4. A cuprous oxide hollow nanosphere, characterized in that: The method is prepared by any one of claims 1 to 3.

5. The use of the cuprous oxide hollow nanospheres according to claim 4, characterized in that: The cuprous oxide hollow nano-microspheres are used in electrocatalytic carbon dioxide reduction reactions.

6. An electrode, characterized in that: The electrode is made of the cuprous oxide hollow nano-microspheres described in claim 4.

7. The method for preparing an electrode according to claim 6, characterized in that: The cuprous oxide hollow nanospheres are loaded on carbon paper by drop coating, with a loading amount of 0.2-1 mg / cm 2 .

8. The use of an electrode according to claim 6, characterized in that: The electrode is used in an electrocatalytic carbon dioxide reduction reaction.

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