Amorphous copper-derived copper / cuprous oxide catalyst and its preparation method, application and testing method

Abstract

The present invention relates to the technical field of metal oxide catalysts, and in particular to a method for preparing a copper / cuprous oxide catalyst derived from amorphous copper, comprising the following steps: weighing CuCl2·2H2O in a 100mL beaker, adding ethylene glycol, and stirring to obtain a uniform and transparent solution A; adding tannic acid to solution A, stirring until the tannic acid is completely dissolved to form a clear and transparent solution B; adding a NaOH solution dropwise to solution B, stirring until the color of the solution gradually changes from blue to brown to form a solution C; transferring solution C to a centrifuge tube, centrifuging to obtain a precipitate; washing the precipitate; drying to obtain an amorphous copper oxide; weighing the amorphous copper oxide, introducing nitrogen as a protective gas, generating an instantaneous high temperature in the form of Joule heat synthesis, and obtaining a Cu-Cu2O catalyst with a heterogeneous structure. The present invention realizes the efficient preparation of copper / cuprous oxide catalyst materials, enhances the adsorption of CO2 and intermediates, and promotes C 2+ The product is generated, and the application and testing methods are also disclosed.

Description

Technical Field

[0001] The present invention relates to the technical field of metal oxide catalysts, and in particular to an amorphous copper-derived copper / cuprous oxide catalyst and a preparation method, application and testing method thereof. Background Art

[0002] Among the many CO2 conversion technologies, using renewable electricity to reduce CO2 (CO2RR) to high-value-added chemical fuels can achieve green utilization of carbon and a circular economy. It has the advantages of mild reaction conditions, high degree of customization, and easy large-scale promotion and application.

[0003] Copper (Cu) is an intermediate for carbon monoxide With moderate binding energy, it is currently the only one that can efficiently convert CO2 into multi-carbon products such as ethanol, ethylene, acetic acid and n-propanol (C 2+ ) metal. The valence of Cu has a profound impact on the CO2RR performance. + ) sites can adsorb and activate CO2 molecules, while zero-valent copper (Cu 0 ) sites can facilitate the subsequent proton-electron transfer step. In addition, Cu 0 -Cu + The interface can reduce the energy barrier of CC coupling and promote the formation of multi-carbon products (such as ethylene and ethanol). + ) and zero-valent copper (Cu 0 ) can effectively promote the carbon-carbon (CC) coupling reaction and promote the C 2+ Based on this mechanism, constructing copper-cuprous oxide (Cu-Cu2O) heterostructures is an important strategy to improve the performance of CO2RR and has become a research hotspot in the current CO2RR field.

[0004] Existing Cu-Cu2O technologies mainly include the following:

[0005] (1) Wet chemical reduction-oxidation method: Cu nanoparticles (NPs) are prepared in the liquid phase using a chemical reducing agent (such as NaBH4, ascorbic acid), and then a Cu2O layer is formed on the surface by controlled oxidation (such as air / O2 oxidation, H2O2 treatment) (MaterialsTechnology, 2024, 39, 2387454.).

[0006] (2) Electrochemical deposition-oxidation method: Cu thin film or nanostructure is electrodeposited on a conductive substrate (such as carbon paper, FTO), and then a Cu2O layer is generated by electrochemical oxidation (anodic polarization) or thermal oxidation (Current Analytical Chemistry, 2021, 17(9), 1373-1381.).

[0007] (3) Gas phase oxidation method (thermal oxidation / plasma oxidation): The metal Cu is heated or plasma treated in a gas phase environment to oxidize its surface to form a Cu2O layer (Biomimetics 2019, 4, 42).

[0008] (4) Photochemical reduction method (solution / interface synthesis): Pulsed laser is used to bombard the target material and locally oxidize it to form Cu-Cu2O heterojunction particles. (International Journal of Molecular Sciences, 2024, 6817, 25, 13).

[0009] However, the Cu-Cu2O interface prepared by the wet chemical reduction-oxidation method in the existing technology is unclear and the oxide layer thickness is uneven. The electrochemical deposition-oxidation method requires a conductive substrate and is difficult to mass produce. The gas-phase oxidation method (thermal oxidation / plasma oxidation) has high equipment requirements and is difficult to mass produce. The photochemical reduction method is costly and has low product purity. Summary of the Invention

[0010] In order to solve at least one of the above technical problems, the present invention proposes a copper / cuprous oxide catalyst derived from amorphous copper and its preparation method, application and testing method, which performs Joule thermal shock treatment and rapid cooling treatment on amorphous copper oxide to accurately control the oxygen content of Cu2O and Cu + / Cu 0 The interface density achieves efficient preparation of copper / cuprous oxide catalyst materials, improves the adsorption of CO2 and intermediates, and promotes C 2+ Product generation.

[0011] To achieve the above object, the present invention adopts the following technical solutions:

[0012] The first aspect of the present invention provides a method for preparing a copper / cuprous oxide catalyst derived from amorphous copper, comprising:

[0013] S1, weigh 0.1-0.5 g CuCl2·2H2O into a 100 mL beaker, add 20-80 mL ethylene glycol, place on a magnetic stirrer and stir at a first stirring rate for a first reaction time to obtain a uniform and transparent solution A;

[0014] S2, adding 100-200 mg of tannic acid to solution A, maintaining the first stirring rate until the tannic acid is completely dissolved to form a clear and transparent solution B;

[0015] S3, adding 1-10 mL of the first concentration of NaOH solution dropwise to solution B, stirring at a first stirring rate during the addition, and continuing stirring for a second reaction time after the addition is complete, until the color of the solution gradually changes from blue to brown to form solution C;

[0016] S4, transfer solution C to a 50 mL centrifuge tube and centrifuge at room temperature to obtain a precipitate;

[0017] S5, washing the precipitate; drying the washed precipitate in a vacuum drying oven to obtain a thermodynamically metastable amorphous copper oxide;

[0018] S6, weighing 50-200 mg of amorphous copper oxide and placing it in a corundum crucible, placing the corundum crucible in a graphite boat, introducing nitrogen as a protective gas, generating instantaneous high temperature in the form of Joule heat synthesis, heating the amorphous copper oxide to induce lattice distortion, and then rapidly cooling to obtain a heterostructured Cu-Cu2O catalyst with grain boundaries and oxygen vacancies.

[0019] Preferably, in S1, the first stirring rate is 500-1000 r / min, and the first reaction time is 10-50 minutes.

[0020] Preferably, the first concentration in S3 is 1-5 mol / L; in S3, the NaOH solution is added dropwise to solution B using a pipette at a dropping rate of 1 drop / 1 second; and the second reaction time is 1-30 minutes.

[0021] Preferably, the centrifugal speed in S4 is 5000-10000 r / min, and the centrifugal time is 1-10 minutes.

[0022] Preferably, the washing liquids used in the washing treatment in S5 are deionized water, acetone and ethanol in sequence.

[0023] Preferably, the drying temperature of the vacuum drying oven in S5 is 20-80° C., and the drying time is 8-24 hours.

[0024] Preferably, the Joule heat heating temperature is 800-1200° C., the pulse time is 2 seconds-8 seconds, and the Joule heat synthesis heating control parameters are current intensity and / or pulse time and / or heating atmosphere.

[0025] The second aspect of the present invention provides an amorphous copper-derived copper / cuprous oxide catalyst prepared by the method for preparing the amorphous copper-derived copper / cuprous oxide catalyst as described in the first aspect.

[0026] In a third aspect, the present invention provides a copper / cuprous oxide catalyst derived from amorphous copper as described in the second aspect for use in carbon dioxide reduction.

[0027] A fourth aspect of the present invention provides a method for testing the application of the amorphous copper-derived copper / cuprous oxide catalyst as described in the third aspect to carbon dioxide reduction, comprising the following steps:

[0028] S1′: 10-50 mg of copper / cuprous oxide catalyst, 80-200 μL of Nafion solution, and 1-5 mL of isopropanol are mixed and ultrasonicated for 10-50 minutes to form a uniformly dispersed catalyst ink;

[0029] S2' Use a spray gun to spray the catalyst ink evenly on a 3×3cm 2 The gas diffusion carbon paper surface was used to prepare the gas diffusion electrode, which was then vacuum dried and used for carbon dioxide reduction test.

[0030] S3': The prepared diffusion electrode, titanium mesh-loaded IrOx, and Ag / AgCl electrodes are used as cathode, anode, and reference electrodes, respectively; 10-40 mL of cathode electrolyte and 10-40 mL of anolyte are fed into the anode and cathode chambers separated by the cation exchange membrane via a peristaltic pump for circulation;

[0031] S4' controls the flow of gaseous carbon dioxide at a rate of 10-30 sccm from the gas chamber on the back of the GDE (gas diffusion electrode) through a Sierra C100L gas mass flow controller. During the test, the electrolyte flow rate is maintained at 10-40 mL / min, the outlet gas flow rate is monitored by a mass flow meter, the gas phase products are quantitatively analyzed by a gas chromatograph, and the liquid phase products are measured by a nuclear magnetic resonance spectrometer.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The instantaneous high temperature synthesized by the present invention can induce structural transformation. By adjusting the current, the temperature is instantly raised to 800-1200°C and maintained for 2 seconds, and the Joule heating effect is used to achieve rapid heating of amorphous copper oxide. The instantaneous high temperature intensifies the thermal vibration of atoms in the amorphous copper oxide, deviating from the equilibrium position. At the same time, when the amorphous structure rapidly crystallizes, the atoms cannot be completely arranged in order, resulting in distortion of the lattice parameters (bond length, bond angle), forming a large number of grain boundaries and oxygen vacancies, which are conducive to promoting the adsorption of carbon dioxide and intermediates, thereby promoting C 2+ At the same time, the instantaneous high temperature also promotes the formation of Cu in amorphous copper oxide. 2+ Partially reduced to Cu0, forming a Cu-Cu2O heterostructure.

[0034] By adjusting the heating parameters of Joule heat synthesis, the oxygen content and defect structure can be precisely controlled. At high temperatures, oxygen atoms in the Cu2O lattice escape (such as Cu2O→2Cu + +½O2↑), forming oxygen vacancies; nitrogen as a protective gas can inhibit the re-adsorption of oxygen, ensuring the retention of oxygen vacancies. By adjusting the current intensity and pulse time, the oxygen vacancy concentration can be precisely controlled to avoid Cu 0At the same time, rapid cooling can prevent the oxygen vacancies and grain boundaries generated at high temperatures from disappearing due to long-term heat treatment, and can "freeze" the high-temperature non-equilibrium phase, thus preventing Cu2O from being completely reduced to Cu during long-term heat treatment. 0 , thereby precisely controlling Cu + / Cu 0 Interface density. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The present invention is a flow chart of a method for preparing a copper / cuprous oxide catalyst derived from amorphous copper.

[0036] Figure 2 Scanning electron microscope images of amorphous copper oxide at different magnifications.

[0037] Figure 3 The transmission electron microscope images and electron diffraction patterns of amorphous copper oxide at different magnifications are shown in FIG. Figure 3 a- Figure 3 d is the transmission electron microscope image of amorphous copper oxide at different magnifications. Figure 3 e is Figure 3 Electron diffraction pattern of the boxed area in d.

[0038] Figure 4 Element distribution map of amorphous copper oxide.

[0039] Figure 5 This is a physical picture of amorphous copper oxide, where: Figure 5 a is a physical picture of amorphous copper oxide before Joule thermal shock. Figure 5 b and Figure 5 c are the actual pictures of amorphous copper oxide when heated at 800-1200℃ and cooled after heating.

[0040] Figure 6 This is a scanning electron microscope image of amorphous copper oxide after Joule thermal shock at 800-1200℃ for 2s.

[0041] Figure 7 This is a scanning electron microscope image of amorphous copper oxide subjected to Joule thermal shock for 4s at 800-1200℃.

[0042] Figure 8 This is a scanning electron microscope image of amorphous copper oxide after Joule thermal shock at 800-1200℃ for 6s.

[0043] Figure 9 This is a scanning electron microscope image of amorphous copper oxide after Joule thermal shock at 800-1200℃ for 8s.

[0044] Figure 10 This is a transmission electron microscope image of amorphous copper oxide after Joule thermal shock at 800-1200℃ for 4s.

[0045] Figure 11 This is a high-resolution transmission electron microscopy image of amorphous copper oxide after Joule thermal shock at 800-1200℃ for 4s.

[0046] Figure 12 XRD patterns of amorphous copper oxide at 800-1200°C Joule thermal shock for 2s, 4s, 6s and 8s.

[0047] Figure 13 This is the CO2RR (carbon dioxide reduction) performance diagram of the sample. Figure 13 a is uncalcined amorphous copper oxide, Figure 13 b- Figure 13 e are the CO2RR product distribution diagrams when amorphous copper oxide is subjected to Joule thermal shock at 800-1200℃ for 2s, 4s, 6s, and 8s, respectively.

[0048] Figure 14 For test examples 1 to 4 and the comparative example, ethanol and C 2+ Product distribution map.

[0049] Figure 15 A flow chart of a method for testing an amorphous copper-derived copper / cuprous oxide catalyst for carbon dioxide reduction. DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention.

[0051] Example 1

[0052] Please refer to Figure 1 As shown, a method for preparing a copper / cuprous oxide catalyst derived from amorphous copper comprises:

[0053] S1. Weigh 0.1 g of CuCl2·2H2O into a 100 mL beaker, add 20 mL of ethylene glycol, and stir on a magnetic stirrer at a first stirring rate for a first reaction time to obtain a uniform and transparent solution A.

[0054] It should be noted that the first stirring rate is 500-1000 r / min, and the first reaction time is 10-50 minutes.

[0055] It is understood that ethylene glycol (HOCH2CH2OH) is a polar organic solvent that can effectively dissolve CuCl2・2H2O to form a uniform Cu 2+Its high boiling point (197.3°C) and low volatility can prevent rapid evaporation of the solvent during the reaction and maintain the stability of the system.

[0056] At the same time, the hydroxyl group (-OH) in the ethylene glycol molecule has weak reducing properties and can partially reduce Cu under alkaline conditions (after adding NaOH). 2+ Cu + However, due to the coordination effect of tannic acid and the control of reaction conditions, Cu 2+ Completely reduced to Cu 0 , thereby promoting the amorphous Cu oxide (containing Cu 2+ and Cu + ) formation.

[0057] This weak reducing property avoids Cu 0 The premature generation of Cu2O ensures that the precursor is a compound of oxidized Cu, laying the foundation for the subsequent Joule thermal shock to form Cu-Cu2O (copper / cuprous oxide) heterostructure.

[0058] S2, add 100 mg of tannic acid to solution A, maintain the first stirring rate until the tannic acid is completely dissolved to form a clear and transparent solution B.

[0059] It should be noted that the above-mentioned tannic acid mainly plays the role of structure directing agent and coordination agent in the synthesis process of amorphous Cu oxide. 76 H 52 O 46 ) is a polyphenolic compound containing a large number of phenolic hydroxyl (-OH) and carboxyl (-COOH) functional groups, which can react with Cu 2+ Forming a stable coordination compound. Through coordination, tannic acid can reduce Cu 2+ The free concentration of Cu(OH)2 is reduced, which slows down the reaction rate with NaOH to generate Cu(OH)2, avoids the crystal growth caused by rapid precipitation, and creates conditions for the formation of amorphous structure.

[0060] At the same time, the macromolecular structure of tannic acid can form a three-dimensional network in the solution, wrapping Cu through hydrogen bonding and π-π stacking. 2+ , which limits their orderly arrangement during the reaction. When NaOH solution is added, Cu 2+ With OH - The reaction produces Cu(OH)2, but due to the steric hindrance of the tannic acid network, Cu(OH)2 cannot form a regular crystal lattice and instead forms an amorphous non-crystalline structure.

[0061] When synthesizing amorphous copper oxides by traditional wet chemical methods, complex surfactants or templates are often required. Through the coordination and steric hindrance effects of tannic acid, the morphology and structure of the amorphous precursor can be precisely controlled, laying the foundation for the subsequent Joule thermal shock preparation of highly active copper / cuprous oxide catalyst heterostructures.

[0062] S3, 1 mL of the first concentration of NaOH solution is added dropwise to solution B, stirring at a first stirring rate during the addition. After the addition is complete, stirring is continued for a second reaction time until the color of the solution gradually changes from blue to brown to form solution C.

[0063] It should be noted that the first concentration is 1 mol / L; in S3 , the NaOH solution is added dropwise to solution B using a pipette at a dropping rate of 1 drop / 1 second, and the second reaction time is 1-30 minutes.

[0064] The main chemical reaction equation in S3 is as follows: CuCl₂ + 2NaOH → Cu(OH)₂ + 2NaOH. Crystalline copper hydroxide (Cu(OH)₂) solids appear as a blue precipitate, and the solution is initially blue. However, the coordination and structural guidance effects of tannic acid inhibit the crystallization of copper hydroxide, causing it to exist in an amorphous state. The color deepens to brown due to its structural disorder.

[0065] S4, transfer solution C to a 50 mL centrifuge tube and centrifuge at room temperature to obtain a precipitate.

[0066] It should be noted that the above centrifugal speed is 5000-10000 r / min, and the centrifugal time is 1-10 minutes.

[0067] S5, washing the precipitate with deionized water, acetone and ethanol in sequence; drying the washed precipitate in a vacuum drying oven to obtain a thermodynamically metastable amorphous copper oxide.

[0068] Specifically, the role of deionized water is to remove water-soluble impurities adsorbed on the surface of the precipitate (such as unreacted NaOH, NaCl, tannic acid residues, etc.).

[0069] The role of acetone is that it acts as an organic solvent to dissolve and remove organic residues on the surface of the precipitate (such as ethylene glycol, incompletely reacted tannic acid, etc.). At the same time, acetone is highly volatile and can accelerate the subsequent drying process.

[0070] The role of ethanol is to further clean the acetone residue on the surface of the precipitate and displace water, thereby reducing the moisture content during drying (ethanol has a low boiling point and is easily volatile). The drying temperature of the above vacuum drying oven is 20-80°C, and the drying time is 8-24 hours.

[0071] In this embodiment, thermodynamically metastable amorphous copper oxide is synthesized through coordination regulation and kinetic inhibition. Its disordered structure and high energy state have more active sites than crystalline materials, providing an ideal precursor for the preparation of highly active Cu-Cu2O heterostructures through Joule heating synthesis.

[0072] The following combination Figure 2-4 The structure of amorphous copper oxide and the distribution of Cu and O elements are analyzed in detail.

[0073] Specifically, please refer to Figure 2 and Figure 3 As shown, Figure 2 The scanning electron microscope images of amorphous copper oxide at different magnifications are shown. Figure 3 middle Figure 3 a- Figure 3 d is the transmission electron microscope image of amorphous copper oxide at different magnifications. Figure 3 e is Figure 3 Electron diffraction pattern of the boxed area in d. Figure 4 Element distribution map of amorphous copper oxide.

[0074] from Figure 2 and Figure 3 It can be seen that the amorphous copper oxide synthesized in the above steps (S1-S5) of this embodiment mainly presents a porous amorphous structure. Figure 4 It can be seen that Cu and O elements are evenly distributed inside the amorphous copper oxide.

[0075] S6. 50 mg of amorphous copper oxide is weighed and placed in a corundum crucible. The corundum crucible is placed in a graphite boat. Nitrogen is introduced as a protective gas to generate instantaneous high temperature in the form of Joule heat synthesis. The amorphous copper oxide is heated to induce lattice distortion, and then rapidly cooled (at a cooling rate of approximately 80°C per minute) to obtain a heterostructured Cu-Cu2O catalyst with grain boundaries and oxygen vacancies.

[0076] In this embodiment, the Joule heating temperature is 800-1200°C, the pulse duration is 2 seconds, and the Joule heating parameters are the current intensity and / or the pulse duration and / or the heating atmosphere. In this embodiment, nitrogen is used as a protective gas in the heating atmosphere to create an inert environment, prevent oxidation of Cu2O at high temperatures, and promote the escape of oxygen atoms to form oxygen vacancies. In this embodiment, the current intensity is approximately 100-300 amperes.

[0077] In this embodiment, the instantaneous high temperature synthesized by Joule heat can induce structural transformation. Specifically, by adjusting the current to instantly raise the temperature to 800-1200℃ and maintain it for 2s, the Joule heat effect (Q=I 2Rt) to achieve rapid heating of amorphous copper oxide. The instantaneous high temperature intensifies the thermal vibration of atoms in amorphous copper oxide, deviating from the equilibrium position. At the same time, when the amorphous structure rapidly crystallizes, the atoms cannot be completely arranged in order, resulting in distortion of the lattice parameters (bond length, bond angle), forming a large number of grain boundaries and oxygen vacancies, which are conducive to the adsorption of carbon dioxide and intermediates, thereby promoting C 2+ At the same time, the instantaneous high temperature also promotes the formation of Cu in amorphous copper oxide. 2+ Partially reduced to Cu 0 , forming a Cu-Cu2O heterostructure.

[0078] In addition, the oxygen content and defect structure can be precisely controlled by regulating the heating parameters of Joule heat synthesis. Specifically, the oxygen atoms in the Cu2O lattice escape at high temperature (such as Cu2O→2Cu + +½O2↑), forming oxygen vacancies; nitrogen as a protective gas can inhibit the re-adsorption of oxygen, ensuring the retention of oxygen vacancies. By adjusting the current intensity and pulse time, the oxygen vacancy concentration can be precisely controlled to avoid Cu 0 Excessive production affects catalytic activity.

[0079] In this embodiment, rapid cooling prevents the oxygen vacancies and grain boundaries generated at high temperatures from disappearing due to long-term heat treatment, and can "freeze" the high-temperature non-equilibrium phase, thus preventing Cu2O from being completely reduced to Cu during long-term heat treatment. 0 , thereby precisely controlling Cu + / Cu 0 Interface density.

[0080] In summary, Joule heating synthesis achieves structural reconstruction and defect induction of amorphous copper oxides through instantaneous high temperature, and rapid cooling freezes the non-equilibrium active structure. The two work synergistically to form a highly active Cu-Cu2O heterostructure catalyst, which is a promising catalyst for improving the carbon dioxide reduction (CO2RR) process. 2+ The product provides favorable conditions.

[0081] Example 2

[0082] The same or similar performance effects produced by the same process and / or the same components under the same process conditions during the preparation process will not be repeated in this embodiment and the following embodiments.

[0083] A method for preparing a copper / cuprous oxide catalyst derived from amorphous copper comprises:

[0084] S1. Weigh 0.2 g of CuCl2·2H2O into a 100 mL beaker, add 40 mL of ethylene glycol, and stir on a magnetic stirrer at a stirring rate of 500-1000 rpm for 10-50 minutes to obtain a homogeneous and transparent solution A.

[0085] S2. Add 125 mg of tannic acid to solution A and maintain a stirring rate of 500-1000 r / min until the tannic acid is completely dissolved to form a clear and transparent solution B.

[0086] S3, 4 mL of 2 mol / L NaOH solution was added dropwise to solution B with stirring at a rate of 500-1000 rpm. After the addition was complete, stirring was continued for a second reaction time until the color of the solution gradually changed from blue to brown to form solution C.

[0087] S4, transfer solution C to a 50 mL centrifuge tube and centrifuge at room temperature to obtain a precipitate.

[0088] S5, washing the precipitate with deionized water, acetone and ethanol in sequence; drying the washed precipitate in a vacuum drying oven to obtain a thermodynamically metastable amorphous copper oxide.

[0089] S6, weighing 100 mg of amorphous copper oxide and placing it in a corundum crucible, placing the corundum crucible in a graphite boat, introducing nitrogen as a protective gas, generating instantaneous high temperature in the form of Joule heat synthesis, heating the amorphous copper oxide at a temperature of 800-1200°C with a pulse time of 4 seconds to induce lattice distortion, and then rapidly cooling to obtain a heterostructured Cu-Cu2O catalyst with grain boundaries and oxygen vacancies.

[0090] Example 3

[0091] S1. Weigh 0.3 g of CuCl2·2H2O into a 100 mL beaker, add 60 mL of ethylene glycol, and stir on a magnetic stirrer at a stirring rate of 500-1000 rpm for 10-50 minutes to obtain a homogeneous and transparent solution A.

[0092] S2. Add 150 mg of tannic acid to solution A and maintain a stirring rate of 500-1000 r / min until the tannic acid is completely dissolved to form a clear and transparent solution B.

[0093] S3, add 7 mL of 3 mol / L NaOH solution dropwise to solution B, stirring at a stirring rate of 500-1000 r / min during the addition. After the addition is complete, continue stirring for a second reaction time until the color of the solution gradually changes from blue to brown to form solution C.

[0094] S4, transfer solution C to a 50 mL centrifuge tube and centrifuge at room temperature to obtain a precipitate.

[0095] S5, washing the precipitate with deionized water, acetone and ethanol in sequence; drying the washed precipitate in a vacuum drying oven to obtain a thermodynamically metastable amorphous copper oxide.

[0096] S6, weighing 150 mg of amorphous copper oxide and placing it in a corundum crucible, placing the corundum crucible in a graphite boat, introducing nitrogen as a protective gas, generating instantaneous high temperature in the form of Joule heat synthesis, heating the amorphous copper oxide at a temperature of 800-1200°C with a pulse time of 6 seconds to induce lattice distortion, and then rapidly cooling to obtain a heterostructured Cu-Cu2O catalyst with grain boundaries and oxygen vacancies.

[0097] Example 4

[0098] S1. Weigh 0.5 g of CuCl2·2H2O into a 100 mL beaker, add 20-80 mL of ethylene glycol, and stir on a magnetic stirrer at a stirring rate of 500-1000 rpm for 10-50 minutes to obtain a homogeneous and transparent solution A.

[0099] S2. Add 100-200 mg of tannic acid to solution A and maintain a stirring rate of 500-1000 r / min until the tannic acid is completely dissolved to form a clear and transparent solution B.

[0100] S3, add 10 mL of 5 mol / L NaOH solution dropwise to solution B, stirring at a stirring rate of 500-1000 r / min during the addition. After the addition is complete, continue stirring for a second reaction time until the color of the solution gradually changes from blue to brown to form solution C.

[0101] S4, transfer solution C to a 50 mL centrifuge tube and centrifuge at room temperature to obtain a precipitate.

[0102] S5, washing the precipitate with deionized water, acetone and ethanol in sequence; drying the washed precipitate in a vacuum drying oven to obtain a thermodynamically metastable amorphous copper oxide.

[0103] S6, weighing 200 mg of amorphous copper oxide and placing it in a corundum crucible, placing the corundum crucible in a graphite boat, introducing nitrogen as a protective gas, generating instantaneous high temperature in the form of Joule heat synthesis, heating the amorphous copper oxide at a temperature of 800-1200°C with a pulse time of 8 seconds to induce lattice distortion, and then rapidly cooling to obtain a heterostructured Cu-Cu2O catalyst with grain boundaries and oxygen vacancies.

[0104] The following is a detailed analysis of the structural evolution and performance correlation characterization diagram of the process of forming a heterostructured Cu-Cu2O catalyst from amorphous copper oxide under Joule heat synthesis conditions in the above-mentioned Examples 1 to 4 in combination with the experimental diagrams.

[0105] Specifically, please refer to Figure 5-Figure 8 As shown, Figure 5 a is the physical display of amorphous Cu oxide before Joule thermal shock. Figure 5 b and Figure 5c are physical displays of amorphous Cu oxide when heated at 800-1200℃ and cooled after heating.

[0106] Figure 6 This is a scanning electron microscope image of amorphous copper oxide subjected to Joule thermal shock for 2s at 800-1200℃. Figure 7 This is a scanning electron microscope image of amorphous copper oxide subjected to Joule thermal shock for 4s at 800-1200℃. Figure 8 This is a scanning electron microscope image of amorphous copper oxide subjected to Joule thermal shock at 800-1200℃ for 6s. Figure 9 This is a scanning electron microscope image of amorphous copper oxide after Joule thermal shock at 800-1200℃ for 8s.

[0107] from Figure 6-Figure 9 It can be seen that compared with the uncalcined amorphous copper oxide, spherical particles of 20-50 nm appeared on the sample surface after Joule thermal shock for 2 seconds; after thermal shock for 4 seconds, the sample was obviously agglomerated, and particles of 100-200 nm appeared on the sample surface; after thermal shock for 6 seconds, the sample further agglomerated, and particles of 300-400 nm were formed on the surface; after thermal shock for 8 seconds, the sample further agglomerated, and particles of 400-600 nm were formed on the surface.

[0108] Figure 10 This is a transmission electron microscope image of amorphous copper oxide subjected to Joule thermal shock at 800-1200℃ for 4s. Figure 11 This is a high-resolution transmission electron microscopy image of amorphous copper oxide after Joule thermal shock at 800-1200℃ for 4s. Figure 12 XRD patterns of amorphous copper oxide at 800-1200°C Joule thermal shock for 2s, 4s, 6s and 8s.

[0109] from Figure 10-11 It can be seen from the transmission electron microscope that after Joule thermal shock for 4s, the sample presents a heterogeneous structure in which Cu and Cu2O coexist. Figure 12 The XRD pattern of amorphous copper oxide shows that there is no diffraction peak, showing a typical amorphous structure. After Joule thermal shock for 2-8s, the sample shows obvious Cu and Cu 2+1 The diffraction peak of Cu2O (Cu2O rich in Cu defects) shows a typical Cu-Cu2O heterostructure. With the extension of thermal shock time, the Cu content gradually increases.

[0110] Compared with the technical difficulties of electrochemical method relying on substrate, gas phase oxidation method having high equipment requirements and photochemical reduction method having low product purity, the Joule thermal synthesis technology in this application can be directly synthesized on conductive substrates such as carbon cloth and graphene, avoiding the complex transfer steps required by traditional methods; this technology uses electric current to directly heat the material, concentrating energy in the reaction area, avoiding the waste of overall heating, and can complete the synthesis within seconds, thereby achieving efficient preparation of materials.

[0111] Preparation Example 1

[0112] The amorphous copper-derived copper / cuprous oxide catalyst was prepared using the preparation method of Example 1.

[0113] Preparation Example 2

[0114] The amorphous copper-derived copper / cuprous oxide catalyst was prepared using the preparation method of Example 2.

[0115] Preparation Example 3

[0116] The amorphous copper-derived copper / cuprous oxide catalyst was prepared using the preparation method of Example 3.

[0117] Preparation Example 4

[0118] An amorphous copper-derived copper / cuprous oxide catalyst was prepared using the preparation method of Example 4.

[0119] It should be noted that the amorphous copper-derived copper / cuprous oxide catalysts prepared in Preparation Examples 1 to 4 can be applied to fields including but not limited to carbon dioxide reduction.

[0120] Test Example 1

[0121] Please refer to Figure 15 As shown, a test method for applying an amorphous copper-derived copper / cuprous oxide catalyst to carbon dioxide reduction comprises the following steps:

[0122] S1′: 10-50 mg of the copper / cuprous oxide catalyst prepared in Preparation Example 1, 80-200 μL of Nafion solution, and 1-5 mL of isopropanol were mixed, and ultrasonicated for 10-50 minutes to form a uniformly dispersed catalyst ink;

[0123] S2' Use a spray gun to spray the catalyst ink evenly on a 3×3cm 2 The gas diffusion carbon paper surface was used to prepare the gas diffusion electrode, which was then vacuum dried and used for carbon dioxide reduction test.

[0124] S3': The prepared diffusion electrode, titanium mesh-loaded IrOx, and Ag / AgCl electrodes are used as cathode, anode, and reference electrodes, respectively; 10-40 mL of cathode electrolyte and 10-40 mL of anolyte are fed into the anode and cathode chambers separated by the cation exchange membrane via a peristaltic pump for circulation;

[0125] S4' controls the flow of gaseous carbon dioxide at a rate of 10-30 sccm from the gas chamber on the back of the GDE (gas diffusion electrode) through a Sierra C100L gas mass flow controller. During the test, the electrolyte flow rate is maintained at 10-40 mL / min, the outlet gas flow rate is monitored by a mass flow meter, the gas phase products are quantitatively analyzed by a gas chromatograph, and the liquid phase products are measured by a nuclear magnetic resonance spectrometer.

[0126] Test Example 2

[0127] The same parts as those in Test Example 1 will not be repeated. The difference from Test Example 1 is that this test example uses the copper / cuprous oxide catalyst prepared in Preparation Example 2 for testing.

[0128] Test Example 3

[0129] The same parts as those in Test Example 1 will not be repeated. The difference from Test Example 1 is that this test example uses the copper / cuprous oxide catalyst prepared in Preparation Example 3 for testing.

[0130] Test Example 4

[0131] The same parts as those in Test Example 1 will not be repeated. The difference from Test Example 1 is that this test example uses the copper / cuprous oxide catalyst prepared in Preparation Example 4 for testing.

[0132] Test comparison

[0133] Different from Example 1, the test sample is an amorphous copper oxide that has not been calcined by Joule heat.

[0134] The CO2RR performance of the Cu-Cu2O heterostructure catalyst is described in detail below in conjunction with the experimental figures of Test Examples 1 to 4 above.

[0135] Specifically, if Figure 13 The following is a graph showing the CO2RR (carbon dioxide reduction) performance of the sample. Figure 13 a is uncalcined amorphous copper oxide, Figure 13 b is the distribution diagram of CO2RR products when amorphous copper oxide is subjected to Joule thermal shock at 800-1200℃ for 2s. Figure 13 c is the CO2RR product distribution diagram when amorphous copper oxide is subjected to Joule thermal shock at 800-1200℃ for 4s. Figure 13 d is the distribution of CO2RR products when amorphous copper oxide is subjected to Joule thermal shock at 800-1200℃ for 6s. Figure 13 e is the CO2RR product distribution diagram when amorphous copper oxide is subjected to Joule thermal shock at 800-1200℃ for 8s.

[0136] Figure 14 The ethanol and C of the above test examples 1 to 4 and the comparative example 2+Product distribution map.

[0137] from Figure 13 and Figure 14 It can be seen that in the range of 100~500mA / cm -2 Under the electrochemical window, the CO2RR products of uncalcined amorphous copper oxide are mainly hydrogen, C 2+ The highest Faraday efficiency of the product is only 10.2%, and the Faraday efficiency of ethanol is only 6.4%.

[0138] After 2s of Joule thermal shock at 800-1200℃, the Faraday efficiency of H2 in the product dropped significantly, and C 2+ The Faraday efficiency of the product was significantly increased to 58.7%, and the highest Faraday efficiency of ethanol reached 25.6%. After 4s of Joule thermal shock at 800-1200℃, the Faraday efficiency of H2 in the product dropped to below 15%, and C 2+ The maximum Faraday efficiency reached 72.4%, and the maximum Faraday efficiency of ethanol reached 40.8%. After 6s of Joule thermal shock at 800-1200℃, C 2+ The maximum Faraday efficiency of the product dropped to 47.3%, and the maximum Faraday efficiency of ethanol dropped to 23.3%; after 800-1200℃ Joule thermal shock for 8s, the maximum C 2+ The Faraday efficiency dropped to 39.8%, and the maximum ethanol Faraday efficiency dropped to 10.3%. It can be seen that when amorphous copper oxide is subjected to Joule thermal shock at 800-1200℃, the Cu-Cu2O heterostructure is obtained. This heterostructure has a strong influence on the Cu-Cu2O structure in the CO2RR process. + With Cu 0 Under the synergistic effect of Generate energy barriers to promote ethanol and C 2+ At the same time, when the Joule heat shock time is 4s and the current density is 300mA / cm -2 When C 2+ The maximum Faraday efficiency of the product reaches 72.4%, and the maximum Faraday efficiency of ethanol production can reach 40.8%.

[0139] The above is a specific implementation of the embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of this application.

Claims

1. A method for preparing a copper / cuprous oxide catalyst derived from amorphous copper, characterized in that: include: S1, weigh 0.1-0.5 g CuCl2·2H2O into a 100 mL beaker, add 20-80 mL ethylene glycol, place on a magnetic stirrer and stir at a first stirring rate for a first reaction time to obtain a uniform and transparent solution A; S2, adding 100-200 mg of tannic acid to solution A, maintaining the first stirring rate until the tannic acid is completely dissolved to form a clear and transparent solution B; S3, adding 1-10 mL of the first concentration of NaOH solution dropwise to solution B, stirring at a first stirring rate during the addition, and continuing stirring for a second reaction time after the addition is complete, until the color of the solution gradually changes from blue to brown to form solution C; S4, transfer solution C to a 50 mL centrifuge tube and centrifuge at room temperature to obtain a precipitate; S5, washing the precipitate; The washed precipitate is placed in a vacuum drying oven and dried to obtain thermodynamically metastable amorphous copper oxide; S6, weighing 50-200 mg of amorphous copper oxide and placing it in a corundum crucible, placing the corundum crucible in a graphite boat, introducing nitrogen as a protective gas, generating instantaneous high temperature in the form of Joule heat synthesis, heating the amorphous copper oxide to induce lattice distortion, and then rapidly cooling to obtain a heterostructured Cu-Cu2O catalyst with grain boundaries and oxygen vacancies.

2. The method for preparing the amorphous copper-derived copper / cuprous oxide catalyst according to claim 1, wherein: In the S1, the first stirring rate is 500-1000 r / min, and the first reaction time is 10-50 minutes.

3. The method for preparing the amorphous copper-derived copper / cuprous oxide catalyst according to claim 1, wherein: In said S3, the first concentration is 1-5 mol / L; in said S3, the NaOH solution is added dropwise to solution B using a pipette at a dropping rate of 1 drop / 1 second; and the second reaction time is 1-30 minutes.

4. The method for preparing the amorphous copper-derived copper / cuprous oxide catalyst according to claim 1, wherein: The centrifugal speed in S4 is 5000-10000 r / min, and the centrifugal time is 1-10 minutes.

5. The method for preparing the amorphous copper-derived copper / cuprous oxide catalyst according to claim 1, wherein: The washing liquids used in the washing process in S5 are deionized water, acetone and ethanol in sequence.

6. The method for preparing the amorphous copper-derived copper / cuprous oxide catalyst according to claim 1, wherein: The drying temperature of the vacuum drying oven in S5 is 20-80° C., and the drying time is 8-24 hours.

7. The method for preparing the amorphous copper-derived copper / cuprous oxide catalyst according to claim 1, wherein: The Joule heat heating temperature is 800-1200° C., the pulse time is 2 seconds-8 seconds, and the Joule heat synthesis heating control parameters are current intensity and / or pulse time and / or heating atmosphere.

8. An amorphous copper-derived copper / cuprous oxide catalyst prepared by the method for preparing an amorphous copper-derived copper / cuprous oxide catalyst according to any one of claims 1 to 7.

9. Use of the amorphous copper-derived copper / cuprous oxide catalyst as claimed in claim 8 for carbon dioxide reduction.

10. A method for testing the amorphous copper-derived copper / cuprous oxide catalyst for carbon dioxide reduction according to claim 9, characterized in that: The steps include: S1′: 10-50 mg of copper / cuprous oxide catalyst, 80-200 μL of Nafion solution, and 1-5 mL of isopropanol are mixed and ultrasonicated for 10-50 minutes to form a uniformly dispersed catalyst ink; S2' Use a spray gun to spray the catalyst ink evenly on a 3×3cm 2 The gas diffusion carbon paper surface was used to prepare the gas diffusion electrode, which was then vacuum dried and used for carbon dioxide reduction test. S3': The prepared diffusion electrode, titanium mesh-loaded IrOx, and Ag / AgCl electrodes are used as cathode, anode, and reference electrodes, respectively; 10-40 mL of cathode electrolyte and 10-40 mL of anolyte are fed into the anode and cathode chambers separated by the cation exchange membrane via a peristaltic pump for circulation; S4' controls the flow of gaseous carbon dioxide into the gas chamber on the back of the GDE at a flow rate of 10-30 sccm through a Sierra C100L gas mass flow controller; during the test, the electrolyte flow rate is maintained at 10-40 mL / min, the outlet gas flow rate is monitored by a mass flow meter, the gas phase products are quantitatively analyzed by a gas chromatograph, and the liquid phase products are measured by a nuclear magnetic resonance spectrometer.

Images