阅读说明：本技术 一种有机分子修饰的氧化铜材料及其制备方法与应用 (Organic molecule modified copper oxide material and preparation method and application thereof ) 是由 陈敏康 林洪栋 周慧彬 汪海涛 王干军 冯国鹏 刘文浩 姜山 陆文伟 梁建辉 黄 于 2021-08-25 设计创作，主要内容包括：本发明涉及电化学技术领域,尤其涉及一种有机分子修饰的氧化铜材料及其制备方法与应用。本发明公开了一种有机分子修饰的氧化铜材料的制备方法,该制备方法通过电还原方法制得有机分子修饰的氧化铜材料,且该材料应用在电催化还原二氧化碳中,表面出对产物甲酸良好的选择性以及较低的过电位。由实验数据可知,本申请制得的有机分子修饰的氧化铜材料还原二氧化碳获得的甲酸的法拉第效率可达到71％。(The invention relates to the technical field of electrochemistry, in particular to an organic molecule modified copper oxide material and a preparation method and application thereof. The invention discloses a preparation method of an organic molecule modified copper oxide material, which prepares the organic molecule modified copper oxide material by an electro-reduction method, and the material is applied to electrocatalytic reduction of carbon dioxide, and has good selectivity and lower overpotential on the surface of a product formic acid. According to experimental data, the faradaic efficiency of formic acid obtained by reducing carbon dioxide with the copper oxide material modified by the organic molecules can reach 71%.)

1. A preparation method of an organic molecule modified copper oxide material is characterized by comprising the following steps:

step 1: mixing an ethanol solution of dimethylformamide and a copper nitrate solution, carrying out hydrothermal reaction, and drying to obtain copper oxide;

step 2: dissolving copper oxide in a water and ethanol solution, and then dropwise adding the solution on a gas diffusion layer to obtain the gas diffusion layer loaded with the copper oxide;

and step 3: adding a potassium bicarbonate solution of poly (diallyldimethylammonium chloride) into an electrolytic cell, clamping the gas diffusion layer loaded with copper oxide on an electrode to serve as a working electrode, and performing electrochemical cyclic voltammetry electrolysis in a three-electrode system to obtain the copper oxide material modified by organic molecules.

2. The preparation method according to claim 1, wherein the hydrothermal reaction is carried out at a temperature of 120 to 140 ℃ for 8 to 10 hours.

3. The preparation method according to claim 1, wherein the molar ratio of the poly (diallyldimethylammonium chloride) to the copper oxide is (2-3): 1.

4. the method according to claim 1, wherein the concentration of the aqueous and ethanolic solution of copper oxide is 1 to 2 mg/mL.

5. The method according to claim 1, wherein the loading amount of the copper oxide on the gas diffusion layer is 0.8 to 1.2mg/cm²。

6. The preparation method according to claim 1, wherein the concentration of poly (diallyldimethylammonium chloride) in the potassium bicarbonate solution of poly (diallyldimethylammonium chloride) is 18 to 22 mmol/L.

7. The method according to claim 1, wherein the parameters of the electrochemical cyclic voltammetric electrolysis are: scanning 50-200 circles in a saturated KCl solution at a scanning speed of 50mV/s between-0.6V and-2.0V (vs. Ag/AgCl).

8. Copper oxide material modified with organic molecules, produced by the production process according to any one of claims 1 to 7, characterized by comprising organic molecules and copper oxide;

the organic molecules are coated on the surface of the copper oxide.

9. Use of the organic molecule-modified copper oxide material according to claim 8 for the electrocatalytic reduction of carbon dioxide.

10. A preparation method of formic acid is characterized by comprising the following steps:

in a flowing electrolytic cell of alkaline solution, clamping a gas diffusion layer loaded with copper oxide material modified by organic molecules on an electrode to be used as a working electrode, and carrying out electrocatalytic reaction in a three-electrode system to obtain formic acid; the organic molecule-modified copper oxide material is the organic molecule-modified copper oxide material prepared by the preparation method of any one of claims 1 to 7.

Technical Field

The invention relates to the technical field of electrochemistry, in particular to an organic molecule modified copper oxide material and a preparation method and application thereof.

Background

The hydrogen fuel cell has the advantages of high fuel energy conversion rate, low noise, zero emission and the like, and can be widely applied to vehicles such as automobiles, airplanes and trains, fixed power stations and the like. Since the fuel cell is applied to manned space, underwater submarines and distributed power stations, the fuel cell is always concerned by governments and enterprises of various countries, and under the condition that the coal-electricity occupation ratio is relatively low in the future, the power supply structure of the whole upstream becomes cleaner and cleaner due to the increase of the technical scale of renewable energy sources such as wind energy, solar energy and the like.

Therefore, how to safely and simply prepare hydrogen and store the hydrogen becomes an important direction for developing the research of the fuel cell. In addition to the hydrogen fuel cell, the formic acid fuel cell is widely studied because of its high energy density and safety. The problem of product supply of fuel cells can therefore be solved if hydrogen and formic acid can be easily produced using renewable energy sources.

Furthermore, the carbon dioxide concentration on the earth is continuously increasing and warming the earth due to the large-scale use of fossil energy. The global warming can cause a lot of damages, such as ice thawing, hot wave invasion, storm, flood and drought, and other natural disasters to become very frequent. Therefore, the emission reduction and resource utilization of carbon dioxide are a major problem to be solved urgently by human beings at present. In recent years, techniques such as carbon capture, carbon sequestration, etc. have been developed for capturing and concentrating carbon dioxide in the buried atmosphere, however, these techniques are resource intensive and the technological progress is slow and therefore are not currently the optimal choice. The conversion of carbon dioxide into hydrocarbons with economic benefits, such as high value-added products of methane, formic acid, ethylene, ethanol and the like, by biochemical methods, thermochemical methods, photochemical methods, electrochemical methods and the like is a promising method at present. However, biochemical and photochemical methods are inefficient in conversion, and thermochemical methods require severe reaction conditions such as high temperature and high pressure, and thus are not suitable for large-scale use. In view of the vigorous development of China in the field of new energy, the power generation capacity of renewable clean energy (wind energy and solar energy) is considerable, however, clean energy such as wind energy, solar energy and the like is difficult to be merged into a power grid because of strong intermittence, randomness, volatility and inverse peak shaving performance on the power grid, so that great waste is caused to the electric energy. This resource is well utilized if the electrical energy is converted to chemical energy in a mild way. Therefore, the renewable electric energy is used for converting carbon dioxide in the atmosphere into hydrogen storage materials with high energy density, such as formic acid, and the like, so that the emission of the carbon dioxide can be reduced, the resource waste can be avoided, and the renewable electric energy can be used as a reactant supply end of a formic acid fuel cell and a hydrogen fuel cell, and has important practical significance for relieving double pressure of energy and environment. Therefore, the technical problem to be solved is to provide a carbon dioxide electrochemical catalyst with high selectivity to formic acid.

Disclosure of Invention

In view of this, the present invention provides an organic molecule modified copper oxide material, and a preparation method and an application thereof.

The specific technical scheme is as follows:

the invention provides a preparation method of an organic molecule modified copper oxide material, which comprises the following steps:

step 1: mixing an ethanol solution of dimethylformamide and a copper nitrate solution, carrying out hydrothermal reaction, and drying to obtain copper oxide;

step 2: dissolving copper oxide in a water and ethanol solution, and then dropwise adding the solution on a gas diffusion layer to obtain the gas diffusion layer loaded with the copper oxide;

and step 3: adding a potassium bicarbonate solution of poly (diallyldimethylammonium chloride) into an electrolytic cell, clamping the gas diffusion layer loaded with copper oxide on an electrode to serve as a working electrode, and performing electrochemical cyclic voltammetry electrolysis in a three-electrode system to obtain the copper oxide material modified by organic molecules.

In step 1 of the invention, the volume ratio of the dimethyl formamide to the ethanol is (0.5-1): 1, the concentration of the copper nitrate solution is 0.05-0.10 mol/L;

the temperature of the hydrothermal reaction is 120-140 ℃, and the time is 8-10 h.

In step 2 of the present invention, the gas diffusion layer is preferably carbon paper;

the concentration of the copper oxide water and ethanol solution is 1-2 mg/mL;

the loading amount of the copper oxide on the gas diffusion layer is 0.8-1.2 mg/cm²Preferably 1mg/cm²。

In step 3 of the invention, the concentration of poly (diallyldipotassium) ammonium chloride in the potassium bicarbonate solution of poly (diallyldimethyl) ammonium chloride is 18-22 mmol/L, preferably 20 mmol/L;

the molar ratio of the poly (diallyldimethylammonium chloride) to the copper oxide is (2-3): 1.

the parameters of the electrochemical cyclic voltammetry electrolysis are as follows: scanning 50-200 circles, preferably 50 circles, 100 circles and 200 circles in a saturated KCl solution at a scanning rate of 50mV/s between-0.6V and-2.0V (vs. Ag/AgCl); in the invention, the thicknesses of the organic molecules in the obtained copper oxide modified by the organic molecules are different according to different scanning cycle numbers.

The invention also provides the copper oxide material modified by the organic molecules, which comprises the organic molecules and copper oxide;

the organic molecules are coated on the surface of the copper oxide.

In the invention, organic molecules are coated on the surface of the copper oxide in a physical adsorption mode.

The invention also provides application of the copper oxide material modified by the organic molecules in electrocatalytic reduction of carbon dioxide.

The invention also provides a preparation method of formic acid, which comprises the following steps: the method comprises the following steps:

in a flowing electrolytic cell of alkaline solution, a gas diffusion layer loaded with the copper oxide material modified by the organic molecules is clamped on an electrode to be used as a working electrode, and electrocatalytic reaction is carried out in a three-electrode system to obtain formic acid.

In the invention, the concentration of the alkaline solution is 1M, and the alkaline solution is a potassium hydroxide solution. The electrocatalytic reaction parameters are as follows: formic acid was prepared by potentiostatic electrolysis of the above samples at-0.4, -0.6, -0.8, -1.0vvs. rhe, respectively.

The copper oxide material modified by organic molecules is applied to electrocatalytic reduction of carbon dioxide, and has good selectivity and low overpotential on the surface of a product formic acid.

According to the technical scheme, the invention has the following advantages:

the invention provides a preparation method of an organic molecule modified copper oxide material, which is used for preparing the organic molecule modified copper oxide material by an electro-reduction method, and the material is applied to electrocatalytic reduction of carbon dioxide, and has good selectivity and lower overpotential on the surface of a product formic acid. According to experimental data, the faradaic efficiency of formic acid obtained by reducing carbon dioxide with the copper oxide material modified by the organic molecules can reach 71%.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.

FIG. 1 is a Scanning Electron Microscope (SEM) picture of an organic molecule-modified copper-based catalyst prepared in examples 1 to 4, wherein (a) Raw; (b) PDDA-CV50 laps; (c) PDDA-CV100 laps; (d) PDDA-CV200 laps;

FIG. 2 is an X-ray diffraction (XRD) pattern of copper oxide prepared in examples 2-4;

FIG. 3 is an X-ray photoelectron spectroscopy (XPS) pattern of an organic molecule-modified copper-based catalyst prepared in examples 2-4, wherein (a) Cu2 p; (b) CuLMM; (c) n1 s;

FIG. 4 is a graph of electrochemical carbon dioxide reduction performance of copper-based catalysts modified with organic molecules prepared in examples 2-4;

Detailed Description

In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it should be apparent that the embodiments described below are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Copper oxide is first synthesized by a hydrothermal method. Mixing 10mL of dimethylformamide and 20mL of absolute ethyl alcohol, adding copper nitrate to prepare a 0.07mol/L copper nitrate solution, reacting in an oven at 130 ℃ in a high-pressure reaction kettle for 9 hours, then centrifugally separating the precipitate, washing with deionized water and absolute ethyl alcohol for multiple times, and then drying in a vacuum drying oven at 60 ℃ to obtain copper oxide (marked as Raw).

Example 2

Copper oxide is first synthesized by a hydrothermal method. Mixing 10mL of dimethylformamide and 20mL of absolute ethyl alcohol, adding copper nitrate to prepare a 0.07mol/L copper nitrate solution, reacting in a high-pressure reaction kettle in an oven at 130 ℃ for 9 hours, then carrying out centrifugal separation on the precipitate, washing with deionized water and absolute ethyl alcohol for multiple times, and then drying in a vacuum drying oven at 60 ℃ to obtain copper oxide. Loading a copper oxide catalyst on carbon paper of a gas diffusion layer to serve as a working electrode, taking Pt wires as a counter electrode and an Ag/AgCl (saturated KCl) electrode as a reference electrode, adding 0.1mol/L potassium bicarbonate solution in which 20mMPDDA is dissolved into an electrolytic bath, then adsorbing organic molecules onto the reduced copper oxide catalyst by adopting a cyclic voltammetry method, and taking out the gas diffusion layer after circulating for 50 circles, and drying in vacuum to obtain the organic molecule modified copper-based catalyst (marked as PPDA-CV50 laps).

Example 3

Copper oxide is first synthesized by a hydrothermal method. Mixing 10mL of dimethylformamide and 20mL of absolute ethyl alcohol, adding copper nitrate to prepare a 0.07mol/L copper nitrate solution, reacting in a high-pressure reaction kettle in an oven at 130 ℃ for 9 hours, then carrying out centrifugal separation on the precipitate, washing with deionized water and absolute ethyl alcohol for multiple times, and then drying in a vacuum drying oven at 60 ℃ to obtain copper oxide. Loading a copper oxide catalyst on a gas diffusion layer as a working electrode, taking a Pt wire as a counter electrode, taking an Ag/AgCl (saturated KCl) electrode as a reference electrode, adding 0.1mol/L potassium bicarbonate solution in which 20mMPDDA is dissolved into an electrolytic tank, then adsorbing organic molecules onto the reduced copper oxide catalyst by adopting a cyclic voltammetry method, circulating for 100 circles at-0.6V to-2.0V vs. Ag/AgCl and 50mV/s, taking out the gas diffusion layer, and drying in vacuum to obtain the organic molecule modified copper-based catalyst (marked as PPDA-CV100 laps).

Example 4

Copper oxide is first synthesized by a hydrothermal method. Mixing 10mL of dimethylformamide and 20mL of absolute ethyl alcohol, adding copper nitrate to prepare a 0.07mol/L copper nitrate solution, reacting in a high-pressure reaction kettle in an oven at 130 ℃ for 9 hours, then carrying out centrifugal separation on the precipitate, washing with deionized water and absolute ethyl alcohol for multiple times, and then drying in a vacuum drying oven at 60 ℃ to obtain copper oxide. Loading copper oxide on a gas diffusion layer as a working electrode, taking a Pt wire as a counter electrode, taking an Ag/AgCl (saturated KCl) electrode as a reference electrode, adding 0.1mol/L potassium bicarbonate solution dissolved with 20mMPDDA into an electrolytic bath, then adsorbing organic molecules onto the reduced copper oxide catalyst by adopting a cyclic voltammetry method, circulating for 200 circles at-0.6V to-2.0 Vvs. Ag/AgCl and 50mV/s, taking out the gas diffusion layer, and drying in vacuum to obtain the copper-based catalyst modified by the organic molecules (marked as PPDA-CV200 laps).

Referring to fig. 1, (a) is a scanning electron microscope image of copper oxide before modification of organic molecules, and it can be seen that large particles having a spherical shape are expressed in a micrometer scale. (b) - (d) scanning electron micrographs corresponding respectively to copper-based catalyst materials supporting organic molecules of different thicknesses. It can be seen from the figure that the original large copper oxide particles are fragmented into nanoparticles after cyclic voltammetry scanning in the solution containing PDDA.

Referring to fig. 2, which is an X-ray diffraction pattern of copper oxide before electrolysis and after different times of electrolysis, it can be seen that the oxidized state of Cu had completely transformed into Cu in the metallic phase after 10min of electrolysis, indicating that the catalyst was always present as metallic Cu during the electrolysis test and that cyclic voltammetry adsorption of organic molecules by controlling the potential interval was possible. And the right graph is an X-ray diffraction graph of the organic molecule modified copper nanoparticles after different cycles, and it can be seen that the peak intensity of the crystal plane changes along with the change of the cycles, and the copper nanoparticles after 100 cycles have the minimum strain through calculation.

With reference to X-ray of FIG. 3The photoelectron spectrum (a) shows that the copper oxide after cyclic voltammetry mainly exists in metallic copper, and Cu appears²⁺The satellite peaks may be caused by oxidation in air, and further confirmed from the graph (b) CuLMM that Cu is in a metallic state rather than Cu⁺. Then, it can be seen from the graph (c) N1s that there is indeed a nitrogen peak, which indicates that the organic molecule successfully modifies the copper nanoparticles, and that the adsorption amount of PDDA molecules is also increased as the number of cycles increases by the N/Cu content ratio.

Test examples

The copper oxide prepared in example 1 and the copper-based catalysts prepared in examples 2 to 4 were subjected to an electrochemical carbon dioxide reduction performance test.

The test condition is that under normal temperature and normal pressure, the electrolyte of the cathode and the anode is 1MKOH, and the test is carried out in a flow electrolytic cell. The test uses constant voltage electrolysis from-0.4V to-1.0 Vvs. Loading copper oxide or copper-based catalyst at 0.5cm²Used as a working electrode (1 mg/cm) on a gas diffusion layer (carbon paper)²) The Pt sheet is used as a counter electrode, Ag/AgCl (saturated KCl) is used as a reference electrode, and the Pt sheet is arranged in a flow electrolytic cell for electrochemical performance test. It can be seen from figure 4 that the catalyst (PDDA-CV100laps) showed the best formic acid selectivity after 100 cycles of cycling, and reached the highest at-0.6 vvs. rhe, with a formic acid faraday efficiency of 71%. As the number of cycles increases, the formic acid selectivity decreases, probably due to the organic molecule wrapping being too thick to plug the active sites of the copper-based catalyst. Therefore, when the organic molecule is wrapped in proper thickness, the selectivity of the formic acid product can be obviously improved.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.