A kind of Cu2O nanoparticles and its preparation method and application

Abstract

The present invention belongs to the field of electrocatalysis technology, and specifically relates to a Cu2O nanoparticle, a preparation method, and an application thereof. The Cu2O nanoparticle comprises a hollow cubic Cu2O nanocrystal, wherein a small cubic Cu2O nanocrystal is encapsulated within the hollow structure of the hollow cubic Cu2O nanocrystal. The preparation method comprises the following steps: synthesizing [Cu2(C6H5O7)2] 2‑ , and further reduced, followed by stabilization in air for 7-9 days to obtain the Cu2O nanoparticles. These Cu2O nanoparticles, morphologically hollow cubic Cu2O nanocrystals embedded within solid cubic Cu2O nanocrystals, are particularly suitable for use as catalysts in the electrocatalytic reduction of carbon dioxide, exhibiting excellent electrocatalytic activity and selectivity for ethylene. The method for preparing these Cu2O nanoparticles, provided herein, utilizes a convenient wet synthesis method featuring a simple synthesis method, mild reaction conditions, and readily available raw materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalysis, and in particular relates to Cu2O nanoparticles and a preparation method and application thereof. Background Art

[0002] The widespread use of fossil fuels has led to a significant increase in the concentration of greenhouse gases in the atmosphere, posing a threat to the global climate. The electrocatalytic carbon dioxide reduction reaction (CO2RR) can convert carbon dioxide into substances such as carbon monoxide, methane, ethylene, and formic acid, and therefore plays a unique role in managing climate change.

[0003] Over the past few decades, a wide range of catalysts have been investigated for electrocatalytic reactions, including metal, nonmetal, and molecular catalysts, all of which have demonstrated excellent activity and selectivity towards a wide range of products. Among these catalysts, Cu2O has garnered significant attention due to its high activity. However, since Cu2O can catalyze the production of a wide range of reduction products, improving its selectivity for specific reduction products has been a key research focus. Currently, morphology control has emerged as a practical strategy for designing Cu2O catalysts with high selectivity and activity. Summary of the Invention

[0004] The present invention aims to provide Cu2O nanoparticles, a preparation method and application thereof. By adopting a convenient wet synthesis method with simple synthesis method, mild reaction conditions and readily available raw materials, hollow cubic Cu2O nanocrystals with embedded solid cubic Cu2O nanocrystals can be prepared using basic chemical raw materials. The hollow cubic Cu2O nanocrystals can be used as a catalyst in the electrocatalytic reduction of carbon dioxide and have excellent electrocatalytic activity and selectivity for ethylene.

[0005] Specifically, the present invention first provides a Cu2O nanoparticle, which includes a hollow cubic Cu2O nanocrystal, wherein a small cubic Cu2O nanocrystal is enclosed in the hollow structure of the hollow cubic Cu2O nanocrystal.

[0006] The present invention has found that the Cu2O nanoparticles with the above structure have greatly increased specific surface area, and are therefore particularly suitable for electrocatalytic reduction of carbon dioxide, and have excellent electrocatalytic activity and ethylene selectivity.

[0007] Preferably, the particle size of the hollow cubic Cu2O nanocrystals is 400-1000 nm, and the particle size of the small cubic Cu2O nanocrystals is 200-500 nm.

[0008] The present invention also provides a method for preparing the above-mentioned Cu2O nanoparticles, comprising the following steps:

[0009] Synthesis of copper citrate complex [Cu2(C6H5O7)2] as a precursor2- , and further reduced, and then allowed to stand in the air for 7 to 9 days to obtain the Cu2O nanoparticles.

[0010] The inventors of the present invention accidentally discovered during the research and development process that [Cu2(C6H5O7)2] 2- The Cu2O nanocrystals obtained by reducing the precursor are allowed to stand in the air for 7 to 9 days to obtain hollow cubic Cu2O nanocrystals with solid cubic Cu2O nanocrystals embedded therein. However, if the precursor is changed, or the air atmosphere is changed to an inert gas or vacuum, or the standing time does not reach or exceed 7 to 9 days, the Cu2O nanoparticle morphology described in the present application cannot be obtained.

[0011] Preferably, the [Cu2(C6H5O7)2] 2- The synthesis method comprises the following steps:

[0012] 1) mixing anhydrous copper sulfate, polyvinyl pyrrolidone, and graphene oxide in deionized water and obtaining a first mixed solution after the copper sulfate, polyvinyl pyrrolidone, and graphene oxide are completely dissolved;

[0013] 2) uniformly mixing sodium citrate and sodium carbonate in water to obtain a second mixed solution;

[0014] 3) Add the second mixed solution to the first mixed solution and stir for a period of time to obtain [Cu2(C6H5O7)2] 2- .

[0015] Further preferably, in parts by weight, the anhydrous copper sulfate is 10 to 12 parts by weight, the polyvinyl pyrrolidone is 8 to 10 parts by weight, the graphene oxide is 0.01 to 0.1 parts by weight, the sodium citrate is 18 to 20 parts by weight, and the sodium carbonate is 12 to 14 parts by weight.

[0016] Further preferably, in step 1), the anhydrous copper sulfate, polyvinyl pyrrolidone and graphene oxide are stirred and mixed in deionized water for 15 to 20 minutes to obtain the first mixed solution.

[0017] More preferably, in step 3), the stirring time is 5 to 10 minutes.

[0018] As an example, the reduction step is specifically as follows: first, to the 2- The reducing agent solution is slowly added dropwise to the solution system, and then heated to react for a period of time.

[0019] More preferably, the reducing agent solution is a 10-20 mol / L glucose solution.

[0020] More preferably, the heating reaction temperature is 75-85° C. and the time is 1-3 hours.

[0021] Preferably, after standing in the air for 7 to 9 days, the method further comprises the steps of solid-liquid separation, washing and drying.

[0022] The present invention also provides the use of the Cu2O nanoparticles or the Cu2O nanoparticles prepared by the above preparation method as a CO2 electroreduction catalyst.

[0023] The present invention also provides a method for CO2 electroreduction, comprising the following steps:

[0024] The Cu2O nanoparticles or the Cu2O nanoparticles prepared by the above preparation method are used as catalysts to electro-reduce CO2.

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

[0026] The Cu2O nanoparticles provided herein are hollow cubic Cu2O nanocrystals embedded within solid cubic Cu2O nanocrystals. They are particularly suitable for use as catalysts in the electrocatalytic reduction of carbon dioxide, exhibiting excellent electrocatalytic activity and selectivity for ethylene. The method for preparing these Cu2O nanoparticles, provided herein, utilizes a convenient wet synthesis method featuring a simple synthesis method, mild reaction conditions, and readily available raw materials, including basic chemical raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the description of the prior art in the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 Spectra of the solutions obtained after water bath heating for different times in step (4) of Example 1 of the present invention, wherein "before" represents the spectrum of the solution before water bath heating.

[0029] Figure 2 3 is a scanning electron microscope image of a single Cu2O nanoparticle according to Example 1 of the present invention.

[0030] Figure 3 3 is a scanning electron microscope image of a plurality of Cu2O nanoparticles according to Example 1 of the present invention.

[0031] Figure 4 is the current density of the Cu2O nanoparticles according to Example 2 of the present invention at different overvoltages.

[0032] Figure 5 : This is the Faraday efficiency of the Cu2O nanoparticles according to Example 3 of the present invention for carbon monoxide, methane, ethylene, and hydrogen at different overvoltages; wherein each bar graph corresponds to carbon monoxide, methane, ethylene, and hydrogen from top to bottom. DETAILED DESCRIPTION

[0033] The following examples are intended to illustrate the present invention but are not intended to limit the scope of the present invention. Modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and substance of the present invention are intended to fall within the scope of the present invention.

[0034] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in this field or the product instructions were used. All reagents or instruments without manufacturer specified are conventional products that can be purchased through regular channels.

[0035] Example 1

[0036] This embodiment provides a Cu2O nanoparticle, and the preparation method includes the following steps:

[0037] (1) 10 mL of 6.8 mol / L copper sulfate solution, 9 g of 30,000 molecular weight polyvinyl pyrrolidone, and 50 mg of graphene oxide were magnetically stirred in 170 mL of water for 20 min to dissolve and mix them completely to obtain a light blue first mixed solution;

[0038] (2) mixing sodium citrate and sodium carbonate in deionized water to obtain a mixed solution of sodium citrate having a concentration of 7.4 mol / L and sodium carbonate having a concentration of 12 mol / L, i.e., a second mixed solution;

[0039] (3) Add 10 mL of the second mixed solution to the first mixed solution and continue magnetic stirring for 10 min. The solution will change from light blue to milky blue and then to dark blue, and from clear to turbid and then to clear. The solution containing [Cu2(C6H5O7)2] 2- A mixed solution;

[0040] (4) Slowly add 10 mL of 14 mol / L glucose solution to the mixed solution obtained in step (3). The solution color does not change. After the addition is completed, move to 80°C water bath and heat for 2 hours, then cool to room temperature and let stand for 8 days;

[0041] (5) The supernatant and the precipitate were separated by standing the mixed solution, and the precipitate was repeatedly washed with distilled water and anhydrous ethanol, and then vacuum-dried at 60 °C for 8 h to obtain Cu2O nanoparticles with a hollow cubic structure.

[0042] Figure 1 The spectra of the solution obtained after heating in a water bath for different times in step (4) are shown, wherein the characteristic peak corresponding to 750nm is the copper citrate complex [Cu2(C6H5O7)2] 2- As the water bath heating reaction time progresses, [Cu2(C6H5O7)2] 2- The concentration of α-hydroxy-1-pyridinium decreases continuously, indicating its existence and participation in the synthesis of the structure.

[0043] Example 2 Morphology Characterization of Cu2O Nanoparticles

[0044] The morphology of the Cu2O nanoparticles obtained in Example 1 was characterized using a scanning electron microscope. Figure 2 and Figure 3 As shown, the exterior of the Cu2O nanoparticle is a Cu2O nanocrystal with a hollow cubic structure, and the center of the hollow cubic structure contains a small cubic Cu2O nanocrystal, which greatly increases the surface area of ​​the entire nanoparticle.

[0045] Example 3 Characterization of electrocatalytic performance of Cu2O nanoparticles

[0046] The current density of the Cu2O nanoparticles obtained in Example 1 at different overvoltages was measured. Figure 4 As shown in the figure, it can be found that the current density is at a high level, which indicates that the catalytic activity of Cu2O nanoparticles is very high. As the overvoltage increases, the current density increases and the catalytic activity further improves.

[0047] The Faraday efficiency of the Cu2O nanoparticles obtained in Example 1 for carbon monoxide, methane, ethylene, and hydrogen at different overvoltages was measured. Figure 5 As shown, it can be found that when the overvoltage is between -1.2 and -1.4 V, the Faradaic efficiency of Cu2O nanoparticles for ethylene is greater than 30%, which indicates that Cu2O nanoparticles have high selectivity for ethylene.

[0048] The above embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary engineers and technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for preparing Cu2O nanoparticles, characterized in that: The Cu2O nanoparticles include hollow cubic Cu2O nanocrystals, wherein a small cubic Cu2O nanocrystal is encapsulated in the hollow structure of the hollow cubic Cu2O nanocrystals; The preparation method comprises the following steps: Towards [Cu2(C6H5O7)2] 2- A reducing agent solution is added dropwise to the solution system for reduction, and then allowed to stand in air for 7 to 9 days to obtain the Cu2O nanoparticles; [Cu2(C6H5O7)2] 2- The synthesis method comprises the following steps: 1) mixing anhydrous copper sulfate, polyvinyl pyrrolidone, and graphene oxide in deionized water and obtaining a first mixed solution after the copper sulfate, polyvinyl pyrrolidone, and graphene oxide are completely dissolved; 2) uniformly mixing sodium citrate and sodium carbonate in water to obtain a second mixed solution; 3) Add the second mixed solution to the first mixed solution and stir for a while to obtain [Cu2(C6H5O7)2] 2- .

2. The preparation method according to claim 1, characterized in that In parts by weight, the anhydrous copper sulfate is 10 to 12 parts by weight, the polyvinyl pyrrolidone is 8 to 10 parts by weight, the graphene oxide is 0.01 to 0.1 parts by weight, the sodium citrate is 18 to 20 parts by weight, and the sodium carbonate is 12 to 14 parts by weight.

3. The preparation method according to claim 1, characterized in that In step 3), the stirring time is 5 to 10 minutes.

4. The preparation method according to any one of claims 1 to 3, characterized in that The reduction step is specifically as follows: first, to the 2- The reducing agent solution is slowly added dropwise to the solution system, and then heated to react for a period of time.

5. The preparation method according to claim 4, characterized in that The reducing agent solution is a 10-20 mol / L glucose solution; And / or, the heating reaction temperature is 75-85° C. and the time is 1-3 hours.

6. A Cu2O nanoparticle, characterized in that: The method is prepared according to any one of claims 1 to 5.

7. The Cu2O nanoparticles according to claim 6, characterized in that The particle size of the hollow cubic Cu2O nanocrystals is 400-1000 nm, and the particle size of the small cubic Cu2O nanocrystals is 200-500 nm.

8. Use of the Cu2O nanoparticles prepared by the preparation method according to any one of claims 1 to 5 or the Cu2O nanoparticles according to claim 6 or 7 as a CO2 electroreduction catalyst.

9. A method for CO2 electroreduction, characterized in that: The following steps are involved: The Cu2O nanoparticles prepared by the preparation method according to any one of claims 1 to 5 or the Cu2O nanoparticles according to claim 6 or 7 are used as a catalyst to electro-reduce CO2.

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