Electrocatalyst of magnesium-doped copper oxide nanospheres as well as preparation method and application of electrocatalyst

Abstract

The invention relates to the technical field of synthesis of electrochemical materials, in particular to an electrocatalyst of magnesium-doped copper oxide nanospheres and a preparation method and application of the electrocatalyst, and the electrocatalyst is prepared through a one-step hydrothermal method and is of a nanosphere structure with a uniform microstructure. According to the catalyst, in a wide voltage range from-1.277 V vs.RHE to-1.677 V vs.RHE, relatively high Faraday efficiency of electrochemical reduction of carbon dioxide into C2 + chemicals is realized. In addition, the technology is green and environment-friendly, the raw materials used in the technology are cheap, the preparation process is simple, the energy consumption is low, a new thought is provided for preparation of the electrocatalyst for generating high-added-value products, and the method has a good application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of preparation methods of electrocatalytic materials, and in particular to an electrocatalyst of magnesium-doped copper oxide nanospheres and a preparation method and application thereof. Background Art

[0002] In recent years, excessive consumption of fossil energy has caused the concentration of carbon dioxide in the atmosphere to increase year by year, causing a series of environmental problems. To this end, my country has proposed a dual carbon target in 2020, hoping to optimize the energy structure through the development of carbon reduction and negative carbon technologies. Electrochemical CO2 reduction (ECO2R), as an emerging negative carbon technology, uses renewable energy as a driving force and is expected to achieve the resource conversion of CO2 into value-added chemicals. 2+ Compounds are chemical raw materials with high economic value and are widely used in the fields of medicine, chemical industry, etc. Copper (Cu) is currently used to reduce CO2 to C because of its suitable binding energy for *CO and *H. 2+ The only monometallic catalyst of the compound.

[0003] At present, researchers mainly conduct relevant research through strategies such as morphology regulation, alloying, and single atomization. It is well known that the use of heteroelement doping technology can optimize its interface electronic structure, reduce the adsorption activation energy of CO2, enhance the intrinsic activity, and promote C 2+ Chemical transformation. Related studies have shown that Mg 2+ It has a strong electron-withdrawing effect and can effectively stabilize Cu under electroreduction conditions. δ+ Therefore, the above-mentioned process and material characteristics are helpful to optimize the interface electronic structure of Cu-based materials and promote the efficient electrochemical conversion of CO2 to prepare high value-added C 2+ Chemicals.

[0004] However, due to factors such as multi-proton coupled electron transfer and slow kinetics of CC coupling steps, C 2+ The poor selectivity of the product limits its practical application. Summary of the invention

[0005] The purpose of the present invention is to provide an electrocatalyst of magnesium-doped copper oxide nanospheres and a preparation method and application thereof, which solves the problem that the Cu-based material has poor CO2 adsorption and activation ability and causes the carbon 2+ The problem of low chemical conversion efficiency.

[0006] To achieve the above object, the present invention provides a method for preparing an electrocatalyst of magnesium-doped copper oxide nanospheres, comprising the following steps:

[0007] Weigh copper nitrate trihydrate, anhydrous magnesium sulfate and urea, dissolve them in ethylene glycol solution, and stir them magnetically at room temperature to form a uniform mixed solution;

[0008] Transferring the uniformly mixed solution into an inner container of a high-pressure reactor, and placing the inner container of the high-pressure reactor into an oven for hydrothermal reaction;

[0009] After the hydrothermal reaction is completed, the reaction solution is transferred to a beaker, and deionized water is added to the beaker and stirred at room temperature to remove unreacted substances in the reaction solution, and then the reaction solution is centrifuged to take the precipitate;

[0010] The precipitated part is placed in a vacuum oven for drying to obtain the electrocatalyst of magnesium-doped copper oxide nanospheres.

[0011] Among them, in “weigh copper nitrate trihydrate, anhydrous magnesium sulfate and urea, dissolve in ethylene glycol solution, and stir magnetically at room temperature to form a uniform mixed solution”;

[0012] The amount of copper nitrate trihydrate used is 0.96 mmol; the amount of anhydrous magnesium sulfate used is 0.24 mmol; the amount of urea used is 0.4 g; the amount of ethylene glycol used is 30 ml; and the magnetic stirring time is 0.5 h.

[0013] Among them, in “transferring the uniformly mixed solution into an inner liner of a high-pressure reactor, and placing the inner liner of the high-pressure reactor into an oven for hydrothermal reaction”;

[0014] The reactor specification is 50ml, the reaction temperature is 140°C, and the reaction time is 15h.

[0015] Among them, in “after the hydrothermal reaction is completed, the reaction solution is transferred to a beaker, and deionized water is added to the beaker and stirred at room temperature to remove unreacted substances in the reaction solution, and then the reaction solution is centrifuged to separate the precipitate”;

[0016] The stirring time is 10 minutes.

[0017] Among them, in “Putting the precipitated portion in a vacuum oven and drying it, an electrocatalyst of magnesium-doped copper oxide nanospheres can be obtained”;

[0018] The drying temperature is 60°C.

[0019] The present invention also comprises an electrocatalyst of magnesium-doped copper oxide nanospheres, which is prepared by adopting the preparation method of the electrocatalyst of magnesium-doped copper oxide nanospheres.

[0020] The present invention also includes an application of an electrocatalyst of magnesium-doped copper oxide nanospheres, wherein the electrocatalyst of magnesium-doped copper oxide nanospheres is applied to CO2 reduction.

[0021] The invention discloses an electrocatalyst of magnesium-doped copper oxide nanospheres and a preparation method and application thereof. The magnesium-doped copper-based electrocatalyst has excellent CO2 adsorption and activation ability, stronger mass transfer and diffusion ability, and faster charge transfer rate. Secondly, the preparation method of the invented material is simple, easy to control, has good repeatability, is green and environmentally friendly, and is conducive to large-scale industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0023] Figure 1 This is the XRD spectrum of an electrocatalyst of magnesium-doped copper oxide nanospheres in Example 3.

[0024] Figure 2 These are the SEM, TEM and mapping images of the electrocatalyst of magnesium-doped copper oxide nanospheres in Example 3.

[0025] Figure 3 This is an activity comparison graph of an electrocatalyst of magnesium-doped copper oxide nanospheres in Example 3.

[0026] Figure 4 This is a comparison graph of the current density of an electrocatalyst of magnesium-doped copper oxide nanospheres in Example 3.

[0027] Figure 5 This is the Nyquist spectrum of the electrocatalyst of magnesium-doped copper oxide nanospheres in Example 3.

[0028] Figure 6 This is a normalized current density spectrum of an electrocatalyst of magnesium-doped copper oxide nanospheres in Example 3.

[0029] Figure 7 The present invention is a flow chart of the method for preparing the electrocatalyst of magnesium-doped copper oxide nanospheres. DETAILED DESCRIPTION

[0030] Embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0031] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0032] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0033] S101: Weigh copper nitrate trihydrate, anhydrous magnesium sulfate and urea, dissolve them in ethylene glycol solution, and stir them magnetically at room temperature to form a uniform mixed solution.

[0034] S102: transferring the uniformly mixed solution into an inner container of a high-pressure reactor, and placing the inner container of the high-pressure reactor into an oven for hydrothermal reaction.

[0035] S103: After the hydrothermal reaction is completed, the reaction solution is transferred to a beaker, and deionized water is added to the beaker and stirred at room temperature to remove unreacted substances in the reaction solution. The reaction solution is then centrifuged to obtain a precipitate.

[0036] S104: Drying the precipitated portion in a vacuum oven to obtain an electrocatalyst of magnesium-doped copper oxide nanospheres.

[0037] The specific synthesis reaction formula of the preparation method of the electrocatalyst of magnesium-doped copper oxide nanospheres of this embodiment is as follows:

[0038] CO(NH2)2——→NH3+HCNO(1)

[0039] CuCl2·5H2O+NH3——→Cu(OH)2+NH4Cl(2)

[0040] Cu(OH)2——→CuO+H2O(3)

[0041] MgSO4+NH3·H2O——→Mg(OH)2+(NH4)2SO4(4)

[0042] Mg(OH)2——→MgO+H2O(5)

[0043] Embodiment 1:

[0044] 0.72mmol hexahydrate copper nitrate, 0.48mmol anhydrous magnesium oxide and 0.4g urea were weighed and dissolved in 30ml ethylene glycol, and magnetically stirred at room temperature for 0.5h to form a uniform mixed solution. The obtained mixed solution was transferred to a 50ml hydrothermal reactor for reaction, placed in a constant temperature oven at 140°C for reaction for 15h, cooled to room temperature, and then the reaction solution was transferred to a beaker, and deionized water was added to the beaker and stirred at room temperature for 10min. The reaction solution was centrifuged and the precipitate was taken, and the precipitate was dried to obtain the electrocatalyst of magnesium-doped copper oxide nanospheres (6Mg@CuO).

[0045] Embodiment 2:

[0046] 0.84mmol hexahydrate copper nitrate, 0.36mmol anhydrous magnesium oxide and 0.4g urea were weighed and dissolved in 30ml ethylene glycol, and magnetically stirred at room temperature for 0.5h to form a uniform mixed solution. The obtained mixed solution was transferred to a 50mL hydrothermal reactor for reaction, placed in a constant temperature oven at 140°C for reaction for 15h, cooled to room temperature, and then the reaction solution was transferred to a beaker, and deionized water was added to the beaker and stirred at room temperature for 10min. The reaction solution was centrifuged and the precipitate was taken, and the precipitate was dried to obtain the electrocatalyst (7Mg@CuO) of magnesium-doped copper oxide nanospheres.

[0047] Embodiment 3:

[0048] 0.96mmol hexahydrate copper nitrate, 0.24mmol anhydrous magnesium oxide and 0.4g urea were weighed and dissolved in 30ml ethylene glycol, and magnetically stirred at room temperature for 0.5h to form a uniform mixed solution. The obtained mixed solution was transferred to a 50mL hydrothermal reactor for reaction, placed in a constant temperature oven at 140°C for reaction for 15h, cooled to room temperature, and then the reaction solution was transferred to a beaker, and deionized water was added to the beaker and stirred at room temperature for 10min. The reaction solution was centrifuged and the precipitate was taken, and the precipitate was dried to obtain the electrocatalyst (8Mg@CuO) of magnesium-doped copper oxide nanospheres.

[0049] Embodiment 4:

[0050] 1.08mmol hexahydrate copper nitrate, 0.12mmol anhydrous magnesium oxide and 0.4g urea were weighed and dissolved in 30ml ethylene glycol, and magnetically stirred at room temperature for 0.5h to form a uniform mixed solution. The obtained mixed solution was transferred to a 50mL hydrothermal reactor for reaction, placed in a constant temperature oven at 140°C for reaction for 15h, cooled to room temperature, and then the reaction solution was transferred to a beaker, and deionized water was added to the beaker and stirred at room temperature for 10min. The reaction solution was centrifuged and the precipitate was taken, and the precipitate was dried to obtain the electrocatalyst (9Mg@CuO) of magnesium-doped copper oxide nanospheres.

[0051] Comparative Example:

[0052] 1.2mmol of copper nitrate hexahydrate and 0.4g of urea were weighed and dissolved in 30ml of ethylene glycol, and magnetically stirred at room temperature for 0.5h to form a uniform mixed solution. The obtained mixed solution was transferred to a 50mL hydrothermal reactor for reaction, placed in a constant temperature oven at 140°C for reaction for 15h, cooled to room temperature, and then the reaction solution was transferred to a beaker, and deionized water was added to the beaker and stirred at room temperature for 10min. The reaction solution was centrifuged and the precipitate was taken, and the precipitate was dried to obtain a CuO electrocatalyst (CuO).

[0053] The structure test of the prepared samples was carried out on a German Bruker D8 X-ray diffractometer (Cu-Kα radiation, The range is 10°-80°) and the scanning rate is 7°min-1. Figure 1 As shown, in Example 3, no obvious characteristic peaks are shown in the XRD spectrum, indicating that the Cu species has poor crystallinity and rich defect structures.

[0054] Figure 2 The SEM, TEM and Mapping spectra of the magnesium-doped copper-based electrocatalyst in Example 3. The figure shows that the morphology of the Mg@CuO catalyst sample (magnesium-doped copper oxide nanosphere electrocatalyst) is a nanosphere structure; the Mapping spectrum clearly shows that the Mg element is evenly distributed in the CuO structure. Combined with the XRD spectrum, the successful synthesis of the Mg@CuO catalyst is confirmed.

[0055] Electrocatalytic activity test: The electrocatalytic carbon dioxide reduction performance of the synthesized samples was tested using a three-electrode system in an electrochemical workstation model CHI660 produced by Shanghai Chenhua Company. Figure 3 The activity comparison spectrum of the magnesium-doped copper-based electrocatalyst in Example 3. Figure 3 It can be seen that Mg@CuO catalyst exhibits excellent electrochemical carbon dioxide to C 2+ Properties of chemicals.

[0056] Figure 4 is the C of the magnesium-doped copper-based electrocatalyst in Example 3. 2+ The current density comparison of the products. It can be seen from the figure that Mg@CuO catalyst exhibits excellent electrochemical carbon dioxide to C 2+ The generation rate of the chemical.

[0057] Figure 5 This is the Nyquist spectrum of the magnesium-doped copper-based electrocatalyst in Example 3. The Mg@CuO catalyst has a smaller interfacial charge transfer resistance, which is beneficial to the rapid activation of the reactant molecules.

[0058] Figure 6 It is the normalized current density spectrum of the magnesium-doped copper-based electrocatalyst in Example 3. The normalized current density of the Mg@CuO catalyst is relatively large, indicating that the intrinsic activity of the Mg@CuO catalyst material has been greatly improved.

[0059] Figure 7 The present invention is a flow chart of the method for preparing the electrocatalyst of magnesium-doped copper oxide nanospheres.

[0060] What is disclosed above is only one or more preferred embodiments of the present application, and cannot be used to limit the scope of rights of the present application. Ordinary technicians in this field can understand that all or part of the processes of implementing the above embodiments and equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A method for preparing an electrocatalyst of magnesium-doped copper oxide nanospheres, characterized in that: The following steps are involved: Weigh copper nitrate trihydrate, anhydrous magnesium sulfate and urea, dissolve them in ethylene glycol solution, and stir them magnetically at room temperature to form a uniform mixed solution; Transferring the uniformly mixed solution into an inner container of a high-pressure reactor, and placing the inner container of the high-pressure reactor into an oven for hydrothermal reaction; After the hydrothermal reaction is completed, the reaction solution is transferred to a beaker, and deionized water is added to the beaker and stirred at room temperature to remove unreacted substances in the reaction solution, and then the reaction solution is centrifuged to take the precipitate; The precipitated part is placed in a vacuum oven for drying to obtain the electrocatalyst of magnesium-doped copper oxide nanospheres.

2. The method for preparing the electrocatalyst of magnesium-doped copper oxide nanospheres according to claim 1, characterized in that: In "Weigh copper nitrate trihydrate, anhydrous magnesium sulfate and urea, dissolve them in ethylene glycol solution, and stir them magnetically at room temperature to form a uniform mixed solution"; The amount of copper nitrate trihydrate used is 0.96 mmol; the amount of anhydrous magnesium sulfate used is 0.24 mmol; the amount of urea used is 0.4 g; the amount of ethylene glycol used is 30 ml; and the magnetic stirring time is 0.5 h.

3. The method for preparing the electrocatalyst of magnesium-doped copper oxide nanospheres according to claim 1, characterized in that: In "transferring the uniformly mixed solution into an inner container of a high-pressure reactor, and placing the inner container of the high-pressure reactor into an oven for hydrothermal reaction"; The reactor specification is 50ml, the reaction temperature is 140°C, and the reaction time is 15h.

4. The method for preparing the electrocatalyst of magnesium-doped copper oxide nanospheres according to claim 1, characterized in that: In "After the hydrothermal reaction is completed, the reaction solution is transferred to a beaker, and deionized water is added to the beaker and stirred at room temperature to remove unreacted substances in the reaction solution, and then the reaction solution is centrifuged to take the precipitate"; The stirring time is 10 minutes.

5. The method for preparing the electrocatalyst of magnesium-doped copper oxide nanospheres according to claim 1, characterized in that: In "Placing the precipitated portion in a vacuum oven and drying it to obtain an electrocatalyst of magnesium-doped copper oxide nanospheres"; The drying temperature is 60°C.

6. An electrocatalyst of magnesium-doped copper oxide nanospheres, characterized in that: The electrocatalyst is prepared by the method for preparing the magnesium-doped copper oxide nanospheres as described in any one of claims 1 to 5.

7. An application of an electrocatalyst of magnesium-doped copper oxide nanospheres, using the electrocatalyst of magnesium-doped copper oxide nanospheres as claimed in claim 6, characterized in that: Applied to CO2 reduction.

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