Cu / g-c3n4 supported catalyst, and preparation method and application thereof

Abstract

The application discloses a Cu / g-C3N4 supported catalyst and a preparation method and application thereof. The Cu / g-C3N4 supported catalyst comprises the following steps: preparing Cu nanoparticles with different sizes, and combining the Cu nanoparticles with g-C3N4 nanosheets to form a supported catalyst. The application also provides application of the Cu / g-C3N4 supported catalyst in a carbon monoxide electro-reduction reaction, and high-purity acetic acid solution is directly obtained by using CO as a raw material. The preparation method of the Cu / g-C3N4 supported catalyst is high in controllability, the Cu / g-C3N4 supported catalyst is obtained, and the Cu / g-C3N4 supported catalyst has two catalytic regions of a Cu / g-C3N4 interface and a Cu nanoparticle surface, and the two catalytic regions respectively realize initial hydrogenation, subsequent coupling and hydrogenation of CO, can efficiently catalyze conversion of CO into acetic acid (salt), and simultaneously has excellent stability, and is suitable for commercial use.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a Cu / g-C3N4 supported catalyst, its preparation method, and its application. Background Technology

[0002] The Industrial Revolution created a glorious era of human industrial civilization, but the massive use of fossil fuels inevitably led to an increase in atmospheric CO2 concentration, causing a series of climate problems. To address excessive carbon emissions, the concepts and requirements of carbon peaking and carbon neutrality have emerged. Besides carbon capture and storage, carbon utilization is also a crucial component of carbon neutrality, and the development of renewable and clean energy undoubtedly provides significant support for carbon utilization. Against this backdrop, the electrochemical conversion and utilization of CO2 can not only achieve the preparation of high-value-added chemicals and fuels but also the storage of renewable energy. Compared to traditional thermal conversion methods, electrochemical conversion methods require milder conditions, have adjustable equipment scale, and a wide range of applications, possessing immense application potential. Current research on electrochemical CO2 reduction reactions (CO2RR) has made some progress, especially for C1 products, where highly selective and active preparation can be achieved on various catalysts. In contrast, the selectivity, activity, and specificity of C2+ products still need further improvement. Given the high added value of C2+ products, designing highly efficient catalysts for C2+ products is of considerable importance.

[0003] From a thermodynamic and kinetic perspective, the electrochemical reduction reaction of CO (CORR) has advantages over CO2RR in preparing multi-carbon products, and therefore generally exhibits higher selectivity and activity. From a process perspective, current research on CO2RR mainly focuses on alkaline / neutral electrolytes. During the reaction, the local pH value on the catalyst surface exceeds 7, leading to the inevitable loss of some CO2 in the form of bicarbonate / carbonate, undoubtedly increasing the cost of CO2 regeneration. Currently, the CO2RR process for CO production is more mature. Using polymer electrolysis technology, CO2 can be converted to CO at low cost within ~200 mA / cm². -2Achieving 90% energy efficiency at a given current density. Therefore, cascading CORR and CO2RR can serve as an indirect method for utilizing CO2, and also provides a framework for achieving carbon neutrality while preparing valuable fuels and chemical feedstocks based on CO2RR and storing intermittent renewable electricity. Given that copper-based catalysts possess moderate CO adsorption energy and exhibit unique C2+ product selectivity in CORR, they have been extensively studied and improved to achieve the goal of efficiently preparing a single C2+ product through indirect CO2 utilization. In summary, the preparation of copper-based catalysts suitable for the efficient preparation of a single product in carbon monoxide electroreduction catalysts is particularly important. Summary of the Invention

[0004] To address the technical problems existing in the prior art, this invention provides a Cu / g-C3N4 supported catalyst, its preparation method, and its applications. The preparation method of the Cu / g-C3N4 supported catalyst is mild, simple, low-cost, and environmentally friendly. The obtained Cu / g-C3N4 supported catalyst possesses dual catalytic regions at the Cu-g-C3N4 interface and on the surface of Cu nanoparticles, making it particularly suitable for catalyzing the electroreduction reaction of CO. It catalyzes both the primary hydrogenation process of carbon monoxide and the subsequent carbon-carbon coupling process, significantly improving the selectivity for the electrocatalytic conversion of carbon monoxide to acetic acid (salt). Furthermore, it can be directly applied to CO electrolysis devices containing solid electrolytes to directly obtain acetic acid solutions, maintaining long-term stability and making it suitable for commercial applications.

[0005] The Cu / g-C3N4 supported catalyst provided by this invention has Cu nanoparticles with a particle size of 20-75 nm (specifically 25 nm or 60 nm) and g-C3N4 nanosheets with a particle size of 200 nm-1 μm.

[0006] The preparation method of the Cu / g-C3N4 supported catalyst provided by the present invention includes the following steps: first, Cu nanoparticles and g-C3N4 nanosheets are prepared, and then Cu nanoparticles and g-C3N4 nanosheets are mechanically mixed to form Cu / g-C3N4 supported catalyst.

[0007] Preferably, the specific process for preparing copper nanoparticles is as follows: copper acetylacetonate and L-ascorbic acid are added to oleylamine at room temperature and ultrasonically dispersed, followed by heating reaction. After the reaction is completed, the copper nanoparticles are washed, centrifuged and collected, and stored for later use.

[0008] Preferably, the molar ratio of copper acetylacetonate to L-ascorbic acid is 1:7-10.

[0009] Preferably, the mass ratio of copper acetylacetonate to oleylamine is 1.5-3.3 g / L, specifically 2.2 g / L.

[0010] Preferably, the ultrasonic time is 0.5 hours and the ultrasonic power is 100W.

[0011] Preferably, the heating temperature is 120-170℃ (specifically 130℃), and the heating time is 4-8 hours.

[0012] Preferably, the cleaning solution is a hexane / ethanol mixture with a volume ratio of 5-10:1.

[0013] Preferably, the centrifugation speed is 9000-11000 rpm and the time is 1-3 minutes.

[0014] Preferably, the solution to be stored is a lower alcohol (such as methanol, ethanol or isopropanol), stored in a vacuum glove box, with a water content of less than 0.1 ppm and an oxygen content of less than 5 ppm.

[0015] Preferably, the concentration of copper nanoparticles in the preserved solution is 2-4 g / L, specifically 3 g / L.

[0016] Preferably, the specific process for preparing g-C3N4 nanosheets is as follows: urea is added to an alumina crucible, sealed and annealed, cooled, and then annealed again with the lid open, and cooled to room temperature to obtain g-C3N4 nanosheets.

[0017] Preferably, the first annealing temperature is 400℃, the time is 4 hours, and the heating rate is 10℃ / minute.

[0018] Preferably, the second annealing temperature is 500℃, the time is 4 hours, and the heating rate is 10℃ / minute.

[0019] Preferably, the process for preparing the Cu / g-C3N4 supported catalyst is as follows: first, a Cu nanoparticle solution and a g-C3N4 nanosheet solution are prepared, and then the above solutions are ultrasonically mixed to obtain the Cu / g-C3N4 supported catalyst.

[0020] Preferably, the solvent for the Cu nanoparticle solution and the g-C3N4 nanosheet solution is a lower alcohol containing one to four carbons, such as methanol, ethanol or isopropanol; the concentration of the Cu nanoparticle solution is 2 to 4 g / L; and the concentration of the g-C3N4 nanosheet solution is 2 to 4 g / L.

[0021] Preferably, the volume ratio of Cu nanoparticle solution to g-C3N4 nanosheet solution is 1:1 to 1:6.

[0022] Preferably, the ultrasonic mixing time is 0.4-1h, and the ultrasonic power is 50-150W.

[0023] The present invention also provides a Cu / g-C3N4 supported catalyst gas diffusion electrode.

[0024] The Cu / g-C3N4 supported catalyst gas diffusion electrode provided by the present invention is obtained by spraying the above-mentioned Cu / g-C3N4 supported catalyst onto hydrophobic carbon paper.

[0025] The specific preparation method of the Cu / g-C3N4 supported catalyst gas diffusion electrode is as follows: the Cu / g-C3N4 supported catalyst solution is mixed with Nafion solution, and after being ultrasonically dispersed evenly, the above mixed solution is uniformly sprayed onto hydrophobic carbon paper using a spray gun.

[0026] Preferably, the concentration of the Cu / g-C3N4 supported catalyst solution is 1-6 g / L (specifically, 2 g / L, 3 g / L); the solvent in the Cu / g-C3N4 supported catalyst solution is a lower alcohol, such as methanol, ethanol or isopropanol.

[0027] Preferably, the mass concentration of the Nafion solution is 5-7%.

[0028] Preferably, the volume ratio of Cu / g-C3N4 supported catalyst solution to Nafion solution is 10 to 25:1.

[0029] Preferably, the ultrasonic dispersion time is 0.5-1h, and the ultrasonic power is 50-150W.

[0030] Preferably, the hydrophobic carbon paper can be YLS-30T hydrophobic carbon paper.

[0031] Preferably, the concentration of the Cu / g-C3N4 supported catalyst coated on hydrophobic carbon paper is 1–4 mg / cm³. 2 Specifically, such as 2mg / cm 2 .

[0032] This invention also provides the application of the above-mentioned Cu / g-C3N4 supported catalyst or Cu / g-C3N4 supported catalyst gas diffusion electrode in the direct preparation of acetic acid solution by CO electroreduction reaction.

[0033] The present invention also provides a membrane electrode solid electrolyte battery for carbon monoxide electroreduction, comprising a working electrode; wherein the working electrode is loaded with the above-mentioned Cu / g-C3N4 supported catalyst or Cu / g-C3N4 supported catalyst gas diffusion electrode.

[0034] The Cu / g-C3N4 supported catalyst obtained in this invention is characterized by its abundant Cu / g-C3N4 interfacial structure and copper nanoparticle surface. These two regions can respectively realize the primary hydrogenation of CO and the subsequent coupling-hydrogenation step, thereby achieving highly selective conversion of CO to acetic acid. Compared with existing catalysts, this invention is simple to synthesize, uses less metal, significantly reduces material costs, and is more environmentally friendly in the synthesis process. Furthermore, this invention has significant advantages in the electroreduction of CO to prepare acetic acid (salt), exhibiting high acetic acid (salt) conversion and good catalyst stability.

[0035] Comparing the Cu / g-C3N4 supported catalyst obtained in this invention with a pure copper nanoparticle catalyst, the Cu / g-C3N4 supported catalyst of this invention can achieve 62.8% acetic acid (salt) selectivity in a flow electrolyzer during the CO electroreduction process when a potential of -0.97V relative to the reversible hydrogen electrode is applied, with a corresponding bias current density of 188 mA / cm². 2 Under the same conditions, the acetic acid (salt) selectivity of pure copper nanoparticles is 28.9%, and the deflection current density is 138 mA / cm². 2 This indicates that the electrocatalytic performance of the present invention is significantly superior to that of pure copper nanoparticle catalysts. Furthermore, compared to previously reported catalysts for the electroreduction of CO to acetic acid, the present invention exhibits significant advantages in acetic acid (salt) current density, selectivity, applied potential, energy efficiency, and copper dosage, demonstrating excellent application prospects. Simultaneously, in CO electrolysis devices containing solid electrolytes, the Cu / g-C3N4 supported catalyst obtained in this invention can achieve an efficiency of 100 mA / cm². 2 Achieving 56.5% acetic acid selectivity at a constant current density, directly obtaining a high-purity aqueous solution of acetic acid, and being able to operate continuously and stably for at least 120 hours, demonstrates its good stability for commercial applications. Attached Figure Description

[0036] Figure 1 The image shows the X-ray electron diffraction pattern of the Cu / g-C3N4 supported catalyst obtained in Example 3 of this invention.

[0037] Figure 2 The image shows a transmission electron microscopy image of the Cu / g-C3N4 supported catalyst obtained in Example 3 of this invention.

[0038] Figure 3 The image shows a transmission electron microscopy image of the Cu / g-C3N4 supported catalyst obtained in Example 4 of this invention.

[0039] Figure 4 The images show a performance comparison (Faraday efficiency and acetic acid partial current density) of the Cu / g-C3N4 supported catalyst and the Cu catalyst in the carbon monoxide electroreduction preparation of acetic acid in Example 3 of this invention.

[0040] Figure 5 These are comparative images showing the performance of the Cu / g-C3N4 supported catalyst obtained in Example 3 of this invention and the reported non-precious metal copper-based catalyst in the electroreduction of carbon monoxide to produce acetic acid.

[0041] Figure 6 This is a schematic diagram of the carbon monoxide electroreduction device containing a solid electrolyte used in Embodiment 5 of the present invention;

[0042] Figure 7 The performance of the Cu / g-C3N4 supported catalyst obtained in Example 3 of this invention under different constant current densities in a carbon monoxide electroreduction device containing a solid electrolyte;

[0043] Figure 8 This is a stability test of the Cu / g-C3N4 supported catalyst obtained in Example 3 of the present invention in a carbon monoxide electroreduction device containing a solid electrolyte. Detailed Implementation

[0044] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments. Unless otherwise specified, the methods described are conventional methods. Unless otherwise specified, the raw materials are all available from publicly available commercial sources.

[0045] Example 1: Preparation of Cu / g-C3N4 supported catalyst

[0046] The catalyst is a Cu / g-C3N4 supported catalyst, in which the copper nanoparticles have a particle size of 25 nm and the g-C3N4 nanosheets have a size of 200 nm-1 μm.

[0047] The preparation method of the Cu / g-C3N4 supported catalyst includes the following steps: first, copper nanoparticles and g-C3N4 nanosheets are prepared, and then the copper nanoparticles and g-C3N4 nanosheets are ultrasonically mixed to obtain the Cu / g-C3N4 supported catalyst.

[0048] The specific process for preparing Cu nanoparticles with a particle size of 25 nm is as follows: Copper acetylacetonate and L-ascorbic acid are added to oleylamine at room temperature and ultrasonically dispersed (ultrasonic time 0.5 h, ultrasonic power 100 W), wherein the molar ratio of copper acetylacetonate to L-ascorbic acid is 1:7, and the mass ratio of copper acetylacetonate to oleylamine solution is 2.2 g / L. Then, the mixture is heated to 130 °C for 4 h, and washed several times with a hexane / ethanol mixed solution, wherein the volume ratio of hexane to ethanol is 10:1. The copper nanoparticles (particle size of 25 nm) are collected by centrifugation at 10,000 rpm for 2 minutes. The obtained copper nanoparticles are then dispersed in isopropanol solution with a concentration of 3 g / L and stored in a vacuum glove box for later use, with a water content of less than 0.1 ppm and an oxygen content of less than 5 ppm.

[0049] The specific process for preparing g-C3N4 nanosheets is as follows: Urea is added to a covered alumina crucible at room temperature and heated (first step annealing) at a heating rate of 10℃ / min, a heating temperature of 400℃, and a time of 4h; after cooling to room temperature, the resulting yellow powder is ground into powder and added to an open alumina crucible and heated (second step annealing) at a heating rate of 10℃ / min, a heating temperature of 500℃, and a time of 4h; after cooling to room temperature, g-C3N4 nanosheets with a particle size of 200nm-1μm are obtained.

[0050] The specific process for preparing the Cu / g-C3N4 supported catalyst is as follows: First, copper nanoparticles and g-C3N4 nanosheets are dissolved in isopropanol to prepare a 3g / L solution. After being evenly dispersed, the two solutions are mixed in a volume ratio of 1:1. After sonication at 100W for 30 minutes, the mixture is placed in a vacuum glove box for storage until use. The water content is less than 0.1ppm and the oxygen content is less than 5ppm.

[0051] Example 2: Preparation of Cu / g-C3N4 supported catalyst and corresponding gas diffusion electrode

[0052] The preparation method of the Cu / g-C3N4 supported catalyst and the corresponding gas diffusion electrode includes the following steps:

[0053] First, copper nanoparticles and g-C3N4 nanosheets were prepared. Then, the copper nanoparticles and g-C3N4 nanosheets were ultrasonically mixed to obtain a Cu / g-C3N4 supported catalyst. Finally, the Cu / g-C3N4 supported catalyst was sprayed onto hydrophobic carbon paper to obtain a gas diffusion electrode.

[0054] The specific process for preparing Cu nanoparticles is as follows: Copper acetylacetonate and L-ascorbic acid are added to oleylamine at room temperature and ultrasonically dispersed (ultrasonic time 0.5 h, ultrasonic power 100 W), wherein the molar ratio of copper acetylacetonate to L-ascorbic acid is 1:7, and the mass ratio of copper acetylacetonate to oleylamine solution is 2.2 g / L. Then, the mixture is heated to 130℃ for 5 h, and washed several times with a hexane / ethanol mixed solution, wherein the volume ratio of hexane to ethanol is 10:1. Copper nanoparticles (particle size 25 nm) are collected by centrifugation at 10000 rpm for 2 minutes. The obtained copper nanoparticles are then dispersed in isopropanol solution with a concentration of 3 g / L and stored in a vacuum glove box for later use, with a water content of less than 0.1 ppm and an oxygen content of less than 5 ppm.

[0055] The specific process for preparing g-C3N4 nanosheets is as follows: Urea is added to a covered alumina crucible at room temperature and heated (first step annealing) at a heating rate of 10℃ / min, a heating temperature of 400℃, and a time of 4h; after cooling to room temperature, the resulting yellow powder is ground into powder and added to an open alumina crucible and heated (second step annealing) at a heating rate of 10℃ / min, a heating temperature of 500℃, and a time of 4h; after cooling to room temperature, g-C3N4 nanosheets with a particle size of 0.2-1μm are obtained.

[0056] The specific process for preparing the Cu / g-C3N4 supported catalyst is as follows: First, copper nanoparticles and g-C3N4 nanosheets are dissolved in isopropanol to prepare a 2g / L solution. After being evenly dispersed, the two solutions are mixed in a volume ratio of 1:1. After sonication at 100W for 30 minutes, the mixture is placed in a vacuum glove box for storage until use. The water content is less than 0.1ppm and the oxygen content is less than 5ppm.

[0057] The specific process for preparing the Cu / g-C3N4 supported catalyst gas diffusion electrode is as follows: First, the Cu / g-C3N4 supported catalyst solution is ultrasonically dispersed evenly, with a concentration of 2 g / L. Then, Nafion solution with a mass concentration of 5% is added, where the volume ratio of the Cu / g-C3N4 supported catalyst solution to the Nafion solution is 15:1. The mixture is ultrasonically dispersed for 1 hour. Afterward, the solution is uniformly sprayed onto hydrophobic carbon paper (model YLS-30T) using a spray gun, with a Cu / g-C3N4 supported catalyst coating concentration of 2 mg / cm³. 2 Dry and set aside for later use.

[0058] Example 3: Preparation of 25nm Cu / g-C3N4 supported catalyst and corresponding gas diffusion electrode

[0059] The preparation method of the Cu / g-C3N4 supported catalyst and the corresponding gas diffusion electrode includes the following steps:

[0060] First, copper acetylacetone and L-ascorbic acid were added to an oleylamine solution at a molar ratio of 1:7 and ultrasonically dispersed evenly (ultrasonic time 0.5 h, ultrasonic power 100 W). The mass ratio of copper acetylacetone to oleylamine solution was 2.2 g / L. Then, the solution was heated to 130 °C for 4 h. The copper nanoparticles were then washed with a hexane / ethanol mixture at a volume ratio of 10:1 and centrifuged at 10,000 rpm for 2 minutes to collect the copper nanoparticles (particle size 25 nm), which were then stored in isopropanol for later use.

[0061] Urea was added to a covered alumina crucible at room temperature and annealed in two steps at a heating rate of 10℃ / min. The first step was covered annealing at 400℃ for 4 hours. After cooling to room temperature, the mixture was ground into powder. The second step was open annealing at 500℃ for 4 hours. After cooling, the mixture was ground again to obtain g-C3N4 nanosheets.

[0062] Subsequently, copper nanoparticles and g-C3N4 nanosheets were dispersed in isopropanol at a concentration of 3 g / L. After being ultrasonically dispersed evenly, the two solutions were mixed at a volume ratio of 1:6 and ultrasonically dispersed for 0.5 h to obtain a Cu / g-C3N4 supported catalyst solution.

[0063] Finally, a 5% Nafion solution was added to the Cu / g-C3N4 supported catalyst solution (concentration 3 g / L), with a volume ratio of Cu / g-C3N4 supported catalyst solution to Nafion solution of 15:1. After ultrasonic dispersion for 0.5–1 h, the solution was uniformly sprayed onto YLS-30T hydrophobic carbon paper using a spray gun, achieving a Cu / g-C3N4 supported catalyst dispersion of 2 mg / cm³. 2 .

[0064] Testing revealed that the copper nanoparticles in the Cu / g-C3N4 supported catalyst obtained in this embodiment had a particle size of 25 nm, and the g-C3N4 nanosheets had a size of 200 nm to 1 μm.

[0065] Figure 1 The image shows the X-ray electron diffraction pattern of the Cu / g-C3N4 supported catalyst obtained in Example 3 of this invention. As can be seen from the image, the catalyst obtained by this method is mainly composed of copper and g-C3N4 material, and the phases are uniform.

[0066] Figure 2The image shows a transmission electron microscopy image of the Cu / g-C3N4 supported catalyst obtained in Example 3 of this invention. As can be seen from the image, the copper nanoparticles in the catalyst obtained by this method have a particle size of 25 nm, the g-C3N4 nanosheets have a size of 200 nm-1 μm, and the copper, carbon, and nitrogen elements are evenly distributed.

[0067] Example 4: Preparation of a 60nm Cu / g-C3N4 supported catalyst and the corresponding gas diffusion electrode

[0068] The preparation method of the Cu / g-C3N4 supported catalyst and the corresponding gas diffusion electrode includes the following steps:

[0069] First, copper acetylacetone and L-ascorbic acid were added to an oleylamine solution at a molar ratio of 1:7 and ultrasonically dispersed evenly (ultrasonic time 0.5 h, ultrasonic power 100 W). The mass ratio of copper acetylacetone to oleylamine solution was 2.2 g / L. Then, the solution was heated to 170 °C for 4 h. The copper nanoparticles were then washed with a hexane / ethanol mixture at a volume ratio of 8:1 and centrifuged at 9000 rpm for 2 minutes to collect the copper nanoparticles (particle size 60 nm). The collected nanoparticles were stored in isopropanol for later use.

[0070] Urea was added to a covered alumina crucible at room temperature and sintered in two steps at a heating rate of 10℃ / min. The first step was covered annealing at 400℃ for 4 hours. After cooling to room temperature, the mixture was ground into powder. The second step was open annealing at 500℃ for 4 hours. After cooling, the mixture was ground again to obtain g-C3N4 nanosheets.

[0071] Subsequently, copper nanoparticles and g-C3N4 nanosheets were dispersed in isopropanol at a concentration of 3 g / L. After being ultrasonically dispersed evenly, the two solutions were mixed at a volume ratio of 1:6 and ultrasonically dispersed for 0.5 h to obtain a Cu / g-C3N4 supported catalyst solution.

[0072] Finally, a 5% Nafion solution was added to the Cu / g-C3N4 supported catalyst solution (concentration 3 g / L), with a volume ratio of Cu / g-C3N4 supported catalyst solution to Nafion solution of 15:1. After ultrasonic dispersion for 0.5–1 h, the solution was uniformly sprayed onto YLS-30T hydrophobic carbon paper using a spray gun, achieving a Cu / g-C3N4 supported catalyst dispersion of 2 mg / cm³. 2 .

[0073] Testing revealed that the copper nanoparticles in the Cu / g-C3N4 supported catalyst obtained in this embodiment had a particle size of 60 nm, and the g-C3N4 nanosheets had a size of 200 nm to 1 μm.

[0074] Figure 3 The image shows a transmission electron microscopy image of the Cu / g-C3N4 supported catalyst obtained in Example 4 of this invention. As can be seen from the image, the particle size of the copper nanoparticles in the catalyst obtained by this method is 60 nm, and the size of the g-C3N4 nanosheets is 200 nm-1 μm.

[0075] Experimental Example 5: Performance Testing of Cu / g-C3N4 Supported Catalyst Gas Diffusion Electrode

[0076] The Cu / g-C3N4 supported catalyst gas diffusion electrode prepared in Example 3 was cut into 1cm*1cm carbon paper as the working electrode, and its activity as a carbon monoxide electroreduction catalyst in a flow electrolyzer was measured in 1mol / L KOH solution.

[0077] The scanning potential range was -0.57 to -1.17 V, with a sampling interval of 0.1 V. The resulting acetic acid selectivity and bias current density curves are shown below. Figure 4 As shown, by Figure 4 It can be seen that at a potential of -0.87V, the Faraday efficiency of acetic acid during electroreduction is 62.8%, and the deflection current density is 188 mA / cm². 2 While unmodified copper nanoparticles (i.e., the copper nanoparticles prepared in Example 3) under the same conditions, Figure 4 The acetic acid shown has a Faraday efficiency of 28.9% and a deflection current density of 138 mA / cm². 2 The results show that the Cu / g-C3N4 supported catalyst prepared in this invention exhibits high current density and high selectivity in the electroreduction of carbon monoxide to acetic acid, showing a significant improvement compared to unmodified copper nanoparticles in the electroreduction of carbon monoxide to acetic acid.

[0078] At the same time, such as Figure 5 As shown, compared with previously reported high-efficiency catalysts, the Cu / g-C3N4 supported catalyst of the present invention has advantages in selectivity, current density, overpotential, copper dosage, and energy efficiency in the reaction of carbon monoxide electroreduction to prepare acetic acid, proving the excellent performance of the catalyst of the present invention.

[0079] Furthermore, the Cu / g-C3N4 supported catalyst of the present invention is used in a carbon monoxide electroreduction device containing a solid electrolyte (see schematic diagram of its structure). Figure 6 High-purity acetic acid solution can be directly obtained from this process, and it can operate continuously for more than 120 hours. For example... Figure 7 As shown, the Cu / g-C3N4 supported catalyst obtained in this invention can achieve a speed of 100 mA / cm². 2 A selectivity of 56.5% for acetic acid was achieved at a constant current density. (For example...) Figure 7As shown, the Cu / g-C3N4 supported catalyst of the present invention has good stability and good application prospects.

[0080] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. Application of a Cu / g-C3N4 supported catalyst in the electroreduction reaction of CO to prepare acetic acid or acetic acid solution; The Cu nanoparticles in the Cu / g-C3N4 supported catalyst have a particle size of 20-75 nm, and the g-C3N4 nanosheets have a particle size of 200 nm-1 μm. The preparation method of the Cu / g-C3N4 supported catalyst includes the following steps: First, Cu nanoparticle solution and g-C3N4 nanosheet solution were prepared, and then the above solutions were ultrasonically mixed to obtain Cu / g-C3N4 supported catalyst. The concentration of Cu nanoparticle solution is 2-4 g / L; the concentration of g-C3N4 nanosheet solution is 2-4 g / L. The volume ratio of Cu nanoparticle solution to g-C3N4 nanosheet solution is 1:1 to 1:

6.

2. The application according to claim 1, characterized in that: The preparation method of Cu nanoparticles includes the following steps: copper acetylacetonate and L-ascorbic acid are added to oleylamine at room temperature and ultrasonically dispersed, followed by heating reaction. After the reaction is completed, the Cu nanoparticles are washed, centrifuged and collected, and stored for later use.

3. The application according to claim 2, characterized in that: The molar ratio of copper acetylacetone to L-ascorbic acid is 1:7-10; Alternatively, the mass ratio of copper acetylacetone to oleylamine is 1.5-3.3 g / L; Alternatively, the heating temperature is 120-170℃, and the heating time is 4-8 hours; Alternatively, the cleaning solution is a hexane / ethanol mixture with a volume ratio of 5-10:1; Alternatively, the centrifugation collection speed is 9000-11000 rpm, and the time is 1-3 minutes; Alternatively, the preserved solution is a lower alcohol, stored in a vacuum glove box, with a water content of less than 0.1 ppm and an oxygen content of less than 5 ppm.

4. The application according to claim 1, characterized in that: The preparation method of g-C3N4 nanosheets includes the following steps: adding urea into an alumina crucible, sealing and annealing, cooling and then opening and annealing again, cooling to room temperature to obtain g-C3N4 nanosheets.

5. The application according to claim 4, characterized in that: The first annealing step is performed at a temperature of 400℃ for 4 hours, with a heating rate of 10℃ / minute. The second annealing step is performed at a temperature of 500℃ for 4 hours, with a heating rate of 10℃ / minute.

6. The application according to claim 1, characterized in that: The solvents for Cu nanoparticle solutions and g-C3N4 nanosheet solutions are lower alcohols containing one to four carbons. The ultrasonic mixing time is 0.4-1 hour, and the ultrasonic power is 50-150W.

7. Application of a Cu / g-C3N4 supported catalyst gas diffusion electrode in the electroreduction reaction of CO to prepare acetic acid or acetic acid solution; The preparation method of the Cu / g-C3N4 supported catalyst gas diffusion electrode includes the following steps: The Cu / g-C3N4 supported catalyst solution was mixed with Nafion solution and ultrasonically dispersed. The mixed solution was then sprayed onto hydrophobic carbon paper using a spray gun. The Cu nanoparticles in the Cu / g-C3N4 supported catalyst have a particle size of 20-75 nm, and the g-C3N4 nanosheets have a particle size of 200 nm-1 μm. The preparation method of the Cu / g-C3N4 supported catalyst includes the following steps: First, Cu nanoparticle solution and g-C3N4 nanosheet solution were prepared, and then the above solutions were ultrasonically mixed to obtain Cu / g-C3N4 supported catalyst. The concentration of Cu nanoparticle solution is 2-4 g / L; the concentration of g-C3N4 nanosheet solution is 2-4 g / L. The volume ratio of Cu nanoparticle solution to g-C3N4 nanosheet solution is 1:1 to 1:

6.

8. The application according to claim 7, characterized in that: The preparation method of Cu nanoparticles includes the following steps: copper acetylacetonate and L-ascorbic acid are added to oleylamine at room temperature and ultrasonically dispersed, followed by heating reaction. After the reaction is completed, the Cu nanoparticles are washed, centrifuged and collected, and stored for later use.

9. The application according to claim 8, characterized in that: The molar ratio of copper acetylacetone to L-ascorbic acid is 1:7-10; Alternatively, the mass ratio of copper acetylacetone to oleylamine is 1.5-3.3 g / L; Alternatively, the heating temperature is 120-170℃, and the heating time is 4-8 hours; Alternatively, the cleaning solution is a hexane / ethanol mixture with a volume ratio of 5-10:1; Alternatively, the centrifugation collection speed is 9000-11000 rpm, and the time is 1-3 minutes; Alternatively, the preserved solution is a lower alcohol, stored in a vacuum glove box, with a water content of less than 0.1 ppm and an oxygen content of less than 5 ppm.

10. The application according to claim 7, characterized in that: The preparation method of g-C3N4 nanosheets includes the following steps: adding urea into an alumina crucible, sealing and annealing, cooling and then opening and annealing again, cooling to room temperature to obtain g-C3N4 nanosheets.

11. The application according to claim 10, characterized in that: The first annealing step is performed at a temperature of 400℃ for 4 hours, with a heating rate of 10℃ / minute. The second annealing step is performed at a temperature of 500℃ for 4 hours, with a heating rate of 10℃ / minute.

12. The application according to claim 7, characterized in that: The solvents for Cu nanoparticle solutions and g-C3N4 nanosheet solutions are lower alcohols containing one to four carbons. The ultrasonic mixing time is 0.4-1 hour, and the ultrasonic power is 50-150W.

13. The application according to claim 7, characterized in that: The concentration of the Cu / g-C3N4 supported catalyst solution is 1-6 g / L; the solvent in the Cu / g-C3N4 supported catalyst solution is a lower alcohol. The mass concentration of the Nafion solution is 5-7%; The volume ratio of the Cu / g-C3N4 supported catalyst solution to the Nafion solution is 10-25:1; The concentration of the Cu / g-C3N4 supported catalyst coated on hydrophobic carbon paper is 1-4 mg / cm³. 2 .

14. The application according to claim 13, characterized in that: The lower alcohol is methanol, ethanol, or isopropanol.

15. A membrane electrode solid electrolyte battery for carbon monoxide electroreduction, comprising a working electrode; wherein the working electrode is supported on a Cu / g-C3N4 supported catalyst or a Cu / g-C3N4 supported catalyst gas diffusion electrode; The Cu nanoparticles in the Cu / g-C3N4 supported catalyst have a particle size of 20-75 nm, and the g-C3N4 nanosheets have a particle size of 200 nm-1 μm. The preparation method of the Cu / g-C3N4 supported catalyst includes the following steps: First, Cu nanoparticle solution and g-C3N4 nanosheet solution were prepared, and then the above solutions were ultrasonically mixed to obtain Cu / g-C3N4 supported catalyst. The concentration of Cu nanoparticle solution is 2-4 g / L; the concentration of g-C3N4 nanosheet solution is 2-4 g / L. The volume ratio of Cu nanoparticle solution to g-C3N4 nanosheet solution is 1:1 to 1:6; The preparation method of the Cu / g-C3N4 supported catalyst gas diffusion electrode includes the following steps: The Cu / g-C3N4 supported catalyst solution was mixed with Nafion solution and ultrasonically dispersed until uniform. The mixed solution was then sprayed onto hydrophobic carbon paper using a spray gun.

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