Integrated catalyst for electrocapture and conversion, its preparation method, and its application in the electroreduction of flue gas to produce carbon monoxide.

Abstract

This invention relates to an integrated electrocapture and conversion catalyst, its preparation method, and its application in the electroreduction of flue gas to produce carbon monoxide. The catalyst consists of gold nanoparticles modified with thiadiazole-based organic ligands, including 2-amino-5-mercapto-1,3,4-thiadiazole, 2-mercapto-5-methyl-1,3,4-thiadiazole, or 2,5-mercapto-1,3,4-thiadiazole. This invention provides a method for preparing the aforementioned integrated electrocapture and conversion catalyst. This method features mild preparation conditions, a simple and clear process, and good reproducibility. The thiadiazole-based organic molecular layer captures carbon dioxide in a reduced state, achieving local enrichment of carbon dioxide. The enriched carbon dioxide is further reduced to carbon monoxide by the gold nanoparticles. In flue gas with a 15% carbon dioxide concentration, a carbon monoxide Faraday efficiency of up to 80.4% can be obtained.

Description

Technical Field

[0001] This invention belongs to the field of catalysts and their applications; specifically, it relates to an integrated catalyst for electrocapture and conversion, its preparation method, and its application in the electroreduction of flue gas to produce carbon monoxide. Background Technology

[0002] Anthropogenic carbon dioxide emissions, especially those from the combustion of fossil fuels since the Industrial Revolution, have had an indelible impact on global climate. Therefore, it is essential to reduce the accumulation of carbon dioxide in the atmosphere to mitigate the adverse weather changes caused by global warming. Carbon capture, storage, and utilization (CCSU) technology is considered a highly promising technology in strategies to mitigate global warming. Carbon capture is the first step in achieving subsequent carbon dioxide storage and utilization, typically targeting carbon dioxide from point sources (such as power plants) and dilution sources in the atmosphere. Flue gas from coal-fired power plants typically contains approximately 10-15% CO2, 3-5% O2, and other low-concentration impurities, while dilution sources in the atmosphere contain only trace amounts of CO2, approximately 412 ppm (~0.04%), making it very difficult to capture. Currently, amine-based thermal capture technology is widely used, but traditional carbon capture technologies are mainly thermally driven chemical absorption or adsorption methods, which suffer from high heat loss, poor oxidation resistance, easy degradation of amine capture agents, and easy corrosion of equipment. If the separate capture process can be bypassed and flue gas can be directly utilized, it will be of great significance to the sustainable economic development of the carbon cycle.

[0003] Electrocatalytic carbon dioxide reduction is a chemical process that combines renewable electrical energy to reduce carbon dioxide into high-value-added products. Current research yields chemicals such as carbon monoxide, formic acid / formate, methane, ethylene, and alcohols. Among these, the two-electron products, carbon monoxide and formic acid / formate, offer nearly 100% Faraday efficiency and are the most promising electrolysis products for industrial development. If an electrochemical CO2 reduction strategy can be used as a medium, with industrial waste gas as a feedstock, to synthesize high-value-added chemicals, this represents a feasible strategy for achieving dual-carbon goals.

[0004] Because the CO2 concentration in industrial waste gas is low, typically only 10-15%, insufficient feedstock gas may lead to a large amount of hydrogen evolution reaction during the electrocatalytic CO2 reduction process. Simultaneously, the waste gas also contains 3-5% O2. The presence of oxygen promotes the thermodynamically and kinetically more favorable oxygen reduction reaction, effectively increasing the competition for the electrocatalytic CO2 reduction reaction. Therefore, to achieve the direct utilization of CO2 from flue gas, it is crucial to synthesize catalysts with capture capabilities, high reactivity and selectivity, and low susceptibility to oxygen reduction reactions. Summary of the Invention

[0005] To address the aforementioned issues, we provide an integrated electrocapture and conversion catalyst and its preparation method. This type of catalyst possesses a redox active component that can accept electrons to form a reduced state and couple with low-concentration carbon dioxide, achieving localized enrichment of carbon dioxide at the catalytic active center. This enables the efficient conversion of carbon dioxide in simulated flue gas into high-value-added carbon monoxide for direct utilization in downstream production. This process facilitates the direct utilization of industrial waste gas, possesses potential for industrial development, and provides a feasible strategy for high-emission enterprises to achieve carbon reduction and negative carbon emissions targets.

[0006] The present invention provides a catalyst that integrates electrocapture and conversion; the catalyst is gold nanoparticles modified with thiadiazole organic molecules, which can anchor low concentrations of carbon dioxide in flue gas in an electron-donating state, thereby achieving the purpose of locally enriching carbon dioxide around the catalyst; the relatively high local concentration of carbon dioxide helps it to be further converted into carbon monoxide.

[0007] The present invention provides a method for preparing the above-mentioned integrated electrocapture and conversion catalyst. This method features mild preparation conditions, a simple and clear preparation process, and good reproducibility.

[0008] This invention provides the application of the aforementioned integrated electrocapture and conversion catalyst in the field of carbon monoxide production from electroreduction flue gas. This catalyst can solve the problem of poor catalytic activity caused by low CO2 concentrations and highly competitive reactions (oxygen reduction reaction) in electroreduction flue gas.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] An integrated catalyst for electrocapture and conversion; the catalyst is gold nanoparticles modified with thiadiazole organic molecules.

[0011] The integrated electrocapture and conversion catalyst described herein; the thiadiazole organic ligand includes 2-amino-5-mercapto-1,3,4-thiadiazole, 2-mercapto-5-methyl-1,3,4-thiadiazole or 2,5-mercapto-1,3,4-thiadiazole.

[0012] The preparation method of the integrated electrocapture and conversion catalyst of the present invention includes the following steps:

[0013] (1) Weigh out thiadiazole organic molecules and amorphous carbon powder and disperse them in ethylene glycol solvent to form a dispersion; weigh out chloroauric acid and dissolve it in ethylene glycol solvent to form a precursor solution; weigh out sodium borohydride and dissolve it in ethylene glycol solvent to form a sodium borohydride solution.

[0014] (2) Add the dispersion from step (1) dropwise into the precursor solution while stirring, place it in an ice bath, and stir continuously;

[0015] (3) Take the sodium borohydride solution from step (1) and add it dropwise to the mixed solution from step (2), and stir continuously under ice bath conditions;

[0016] (4) After the reaction is complete, centrifuge, wash, and dry in a vacuum drying oven.

[0017] The preparation method described above; in step (1), the concentration of thiadiazole organic molecules in the solution obtained by dissolving thiadiazole organic molecules in ethylene glycol is 1.0 mg / mL to 3.6 mg / mL.

[0018] The preparation method described above; the concentration of chloroauric acid in the precursor solution in step (1) is 1.7~5.4 mg / mL.

[0019] The preparation method described above; the concentration of sodium borohydride solution in step (1) is 20~50 mg / mL.

[0020] The preparation method described above involves a molar ratio of thiadiazole organic molecules in the dispersion to chloroauric acid in the precursor solution of 0.8:1 to 2:1.

[0021] The preparation method described above; in step (3), the mass ratio of chloroauric acid to sodium borohydride is 0.4:1 to 1.4:1.

[0022] The present invention relates to the application of an integrated electrocapture and conversion catalyst in the electroreduction of flue gas to produce carbon monoxide. The catalyst is weighed and dispersed in a volatile solvent, and a naphthol reagent is added to the dispersion. The dispersion is continuously sonicated to form a uniform dispersion, which is then drop-coated to form a working electrode. A platinum wire electrode is used as the counter electrode, and a saturated calomel electrode is used as the reference electrode to form a three-electrode testing system connected to an electrochemical workstation. A saturated bicarbonate solution of flue gas is used as the electrolyte. Cyclic voltammetry, linear scanning, and constant potential electrolysis tests are performed. Through the constant potential electrolysis experiment, the corresponding carbon monoxide current density and Faraday effect are calculated.

[0023] The application of electroreduction of flue gas to produce monoxide; volatile solvents include water, methanol, ethanol, isopropanol or N,N-dimethylformamide; bicarbonate solution includes potassium bicarbonate or sodium bicarbonate, with a concentration of 0.1~1 mol / L.

[0024] The application of electroreduction of flue gas to produce monoxide; the test potential range of the constant potential electrolysis experiment is -0.7~-1.3 V vs SCE.

[0025] The specific explanation is as follows:

[0026] This invention proposes a gold nanoparticle catalyst modified with thiadiazole organic molecules, comprising a thiadiazole organic ligand layer and gold nanoparticles. The thiadiazole organic ligand layer serves as the redox active center, anchoring carbon dioxide in flue gas under electron-gain conditions to achieve electrocapture. Simultaneously, carbon dioxide surrounding the catalyst can be reduced to carbon monoxide under the influence of the gold nanoparticle core, achieving electrochemical conversion of carbon dioxide. The thiadiazole organic ligands include 2-amino-5-mercapto-1,3,4-thiadiazole (NH2-C2HN2S2), 2-mercapto-5-methyl-1,3,4-thiadiazole (CH3-C2HN2S2), and 2,5-mercapto-1,3,4-thiadiazole (SH-C2HN2S2). The gold nanoparticles are used to achieve the electrochemical conversion of CO2 to CO. Based on this, the structure of the catalyst is defined as: R-C2HN2S2-Au, where R = CH3, NH2, SH.

[0027] The present invention relates to the application of the above-mentioned integrated electrocapture and conversion catalyst in the field of electroreduction of flue gas to carbon monoxide. It utilizes the ability of thiadiazole-based organic molecular layers to capture carbon dioxide in a reduced state, achieving local enrichment of carbon dioxide; the enriched carbon dioxide is further reduced to carbon monoxide by gold nanoparticles, thereby achieving the goal of high-efficiency electroreduction of flue gas to carbon monoxide. The concentration of carbon dioxide in the flue gas ranges from 8% to 75%.

[0028] The beneficial effects of this invention are:

[0029] (1) The integrated electrocapture and conversion catalyst provided by this invention combines thiadiazole redox-active amines with gold nanoparticles. The transition state of carbon dioxide formed by redox-active capture of carbon dioxide is pre-activated, and can then be more effectively reduced by the gold nanoparticles. Our catalyst can not only capture carbon dioxide, but also convert carbon dioxide into carbon monoxide, making it a bifunctional material. The catalyst can achieve a carbon monoxide Faraday efficiency of over 50% at a low CO2 concentration of 8%, realizing the capture and utilization of low-concentration CO2, and demonstrating the ability to convert flue gas into high-value-added CO.

[0030] (2) The catalyst provided by the present invention obtained gold nanoparticles modified with thiadiazole organic molecules through a simple wet chemical reduction method. Compared with ordinary nanocatalysts, which require high temperature and high pressure to synthesize, the catalyst has mild preparation conditions (room temperature), simple process and reproducibility.

[0031] (3) The catalyst provided by this invention, in a potassium bicarbonate solution saturated with flue gas, achieves local enrichment of carbon dioxide concentration near the electrochemically active center through the coupling effect of the surface thiadiazole organic ligands on the low concentration of carbon dioxide in the flue gas after electroreduction. This enables the catalyst to exhibit a significant ability to electrochemically reduce carbon dioxide in flue gas even at low overpotentials. At a potential of -1.2 V vs SCE, this catalyst reduces carbon dioxide in flue gas to carbon monoxide, achieving a carbon monoxide faradaic efficiency of over 40%, with a maximum efficiency of 80.4%. Attached Figure Description

[0032] Figure 1 X-ray powder diffraction pattern of the catalyst NH2-C2HN2S2-Au obtained in Example 1.

[0033] Figure 2 : A transmission electron microscope image of the catalyst NH2-C2HN2S2-Au obtained in Example 1.

[0034] Figure 3 Linear scan curve of the catalyst NH2-C2HN2S2-Au obtained in Example 1 in 0.1 mol / L tetrabutylammonium hexafluorophosphate solution / dimethyl sulfoxide solution;

[0035] Figure 4 X-ray powder diffraction pattern of the catalyst CH3-C2HN2S2-Au obtained in Example 2.

[0036] Figure 5 : A transmission electron microscope image of the catalyst CH3-C2HN2S2-Au obtained in Example 2.

[0037] Figure 6 X-ray powder diffraction pattern of the catalyst SH-C2HN2S2-Au obtained in Example 3.

[0038] Figure 7 : A transmission electron microscope image of the catalyst SH-C2HN2S2-Au obtained in Example 3.

[0039] Figure 8 Linear sweep voltammetry curves of the catalyst NH2-C2HN2S2-Au obtained in Example 1 in argon and flue gas: (a) Linear sweep voltammetry curves of NH2-C2HN2S2-Au catalyst in flue gas and argon atmosphere, (b) Linear sweep voltammetry curves of NH2-C2HN2S2-Au and unmodified gold nanoparticle (Naked Au) catalyst in flue gas.

[0040] Figure 9Faraday efficiency diagrams of carbon monoxide obtained from the catalysts in Examples 1, 2, and 3 at different electrode potentials.

[0041] Figure 10 Example 1: Faraday efficiency of the catalyst for carbon monoxide in flue gas with different carbon dioxide concentrations. Detailed Implementation Plan

[0042] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings. These embodiments will enable those skilled in the art to gain a more comprehensive understanding of the present invention, but they are not intended to limit the present invention in any way.

[0043] Example 1

[0044] The preparation process of the catalyst NH2-C2HN2S2-Au includes the following steps:

[0045] (1) Weigh 16 mg of 2-amino-5-mercapto-1,3,4-thiadiazole (NH2-C2HN2S2) and 20 mg of amorphous carbon powder and disperse them in 10 mL of ethylene glycol solvent to form a dispersion (at this time, the concentration of 2-amino-5-mercapto-1,3,4-thiadiazole organic molecules is 1.6 mg / mL); weigh 54 mg of chloroauric acid trihydrate and dissolve it in 10 mL of ethylene glycol solvent to form a precursor solution (at this time, the concentration of chloroauric acid is 5.4 mg / mL, and the molar ratio of 2-amino-5-mercapto-1,3,4-thiadiazole organic molecules to gold precursor is 0.8:1); weigh sodium borohydride and dissolve it in ethylene glycol solvent to form a sodium borohydride solution (the concentration of sodium borohydride is 50 mg / mL).

[0046] (2) Add the dispersion from step (1) dropwise into the precursor solution while stirring, place it in an ice bath, and stir continuously;

[0047] (3) Add the sodium borohydride solution from step (1) to the mixed solution from step (2) (at this time, the mass ratio of chloroauric acid to sodium borohydride is 1:1), and place it in an ice bath and stir continuously;

[0048] (4) After the reaction is completed, the catalyst is centrifuged, washed three times with ultrapure water and ethanol, and dried in a vacuum drying oven to obtain the catalyst NH2-C2HN2S2-Au.

[0049] Figure 1 The image shows the X-ray powder diffraction pattern of the catalyst NH2-C2HN2S2-Au obtained in Example 1. It can be seen from the image that after modification with the 2-amino-5-mercapto-1,3,4-thiadiazole organic molecule, the NH2-C2HN2S2-Au catalyst still exhibits a typical face-centered cubic crystal phase, but the diffraction peak intensities are relatively weakened. The surface 2,5-mercapto-1,3,4-thiadiazole molecular layer affects the peak intensity of the spectrum. Figure 2 The image shows a transmission electron microscope (TEM) image of the catalyst NH2-C2HN2S2-Au obtained in Example 1. As can be seen from the image, the NH2-C2HN2S2-Au catalyst is uniformly distributed on the surface of the amorphous carbon powder with a small particle size of 2-3 nm, without any agglomeration.

[0050] Figure 3 The linear sweep spectroscopy curves of the catalyst NH2-C2HN2S2-Au obtained in Example 1 under argon and flue gas conditions in a 0.1 mol / L tetrabutylammonium hexafluorophosphate / dimethyl sulfoxide solution are used to illustrate the catalyst's ability to electrocapture carbon dioxide in aprotic solutions. Under argon conditions, the catalyst only exhibits a value at -2.3 V vs Ag / Ag. + The potential peak represents the reduction peak of the ligand 2-amino-5-mercapto-1,3,4-thiadiazole itself. In contrast, it exhibits three reduction peaks under flue gas conditions, located at -1.2 V vs Ag / Ag. + -2.3 V vs Ag / Ag + -2.7 V vs Ag / Ag + -1.2 V vs Ag / Ag + The reduction peak at that point is attributed to the reduction of oxygen in the flue gas; -2.3 V vs Ag / Ag + The reduction peak at [location] is attributed to the reduction of the 2-amino-5-mercapto-1,3,4-thiadiazole ligand, which is clearly observed under an argon atmosphere; -2.7 V vs Ag / Ag + The reduction peak at the point represents the reduction of carbon dioxide in the flue gas to the transition state of the combination of carbon dioxide and 2-amino-5-mercapto-1,3,4-thiadiazole ligand. The appearance of this peak proves that the catalyst NH2-C2HN2S2-Au obtained in Example 1 can capture carbon dioxide in the flue gas and achieve local enrichment of carbon dioxide.

[0051] Example 2

[0052] The preparation process of the catalyst CH3-C2HN2S2-Au includes the following steps:

[0053] (1) Weigh 36.0 mg of 2-mercapto-5-methyl-1,3,4-thiadiazole (CH3-C2HN2S2) and 20 mg of amorphous carbon powder and disperse them in 10 mL of ethylene glycol solvent to form a dispersion (at this time, the concentration of 2-mercapto-5-methyl-1,3,4-thiadiazole organic molecules is 3.6 mg / mL); weigh 26.8 mg of chloroauric acid trihydrate and dissolve it in 10 mL of ethylene glycol solvent to form a precursor solution (at this time, the concentration of chloroauric acid is 2.68 mg / mL, and the molar ratio of 2-mercapto-5-methyl-1,3,4-thiadiazole organic molecules to gold precursor is 2:1); weigh sodium borohydride and dissolve it in ethylene glycol solvent to form a sodium borohydride solution (the concentration of sodium borohydride is 20 mg / mL).

[0054] (2) Add the dispersion from step (1) dropwise into the precursor solution while stirring, place it in an ice bath, and stir continuously;

[0055] (3) Add the sodium borohydride solution from step (1) to the mixed solution from step (2) (at this time, the mass ratio of chloroauric acid to sodium borohydride is 1.4:1), place it in an ice bath, and stir continuously;

[0056] (4) After the reaction is completed, the catalyst is separated by centrifugation, washed three times with ultrapure water and ethanol, and dried in a vacuum drying oven to obtain the catalyst CH3-C2HN2S2-Au.

[0057] Figure 4 The image shows the X-ray powder diffraction pattern of the catalyst CH3-C2HN2S2-Au obtained in Example 2. As can be seen from the image, after modification with the 2-mercapto-5-methyl-1,3,4-thiadiazole organic molecule, the CH3-C2HN2S2-Au catalyst still exhibits a typical gold-centered cubic crystal phase, but the diffraction peak intensities are relatively weakened. The surface 2-mercapto-5-methyl-1,3,4-thiadiazole molecular layer affects the peak intensity of the spectrum. Figure 5 The image shows a transmission electron microscope (TEM) image of the catalyst CH3-C2HN2S2-Au obtained in Example 2. As can be seen from the image, the CH3-C2HN2S2-Au catalyst is uniformly distributed on the surface of the amorphous carbon powder with a small particle size of 2-3 nm, without any agglomeration.

[0058] Example 3

[0059] The preparation process of the catalyst SH-C2HN2S2-Au includes the following steps:

[0060] (1) Weigh 10.0 mg of 2,5-mercapto-1,3,4-thiadiazole (SH-C2HN2S2) and 20 mg of amorphous carbon powder and disperse them in 10 mL of ethylene glycol solvent to form a dispersion (at this time, the concentration of 2,5-mercapto-1,3,4-thiadiazole organic molecules is 1.0 mg / mL); weigh 17 mg of chloroauric acid and dissolve it in 10 mL of ethylene glycol solvent to form a precursor solution (at this time, the concentration of chloroauric acid is 1.7 mg / mL, and the molar ratio of 2-mercapto-5-methyl-1,3,4-thiadiazole organic molecules to gold precursor is 1.5:1); weigh sodium borohydride and dissolve it in ethylene glycol solvent to form a sodium borohydride solution (the concentration of sodium borohydride is 40 mg / mL).

[0061] (2) Add the dispersion from step (1) dropwise into the precursor solution while stirring, place it in an ice bath, and stir continuously;

[0062] (3) Add the sodium borohydride solution from step (1) to the mixed solution from step (2) (at this time, the mass ratio of chloroauric acid to sodium borohydride is 0.4:1), place it in an ice bath, and stir continuously;

[0063] (4) After the reaction was completed, the catalyst was centrifuged, washed three times with ultrapure water and ethanol, and dried in a vacuum drying oven to obtain the catalyst SH-C2HN2S2-Au.

[0064] Figure 6 The image shows the X-ray powder diffraction pattern of the catalyst SH-C2HN2S2-Au obtained in Example 3. As can be seen from the image, after modification with the organic molecule 2,5-mercapto-1,3,4-thiadiazole, the SH-C2HN2S2-Au catalyst only exhibits diffraction peaks belonging to amorphous carbon particles, and no diffraction peaks belonging to gold are found. This is because the thiol groups in the 2,5-mercapto-1,3,4-thiadiazole molecule that do not interact with gold form a network through mutual interaction, which affects the diffraction peaks of gold. Figure 7 The image shows a transmission electron microscope (TEM) image of the catalyst SH-C2HN2S2-Au obtained in Example 3. As can be seen from the image, the particle size of the CH3-C2HN2S2-Au catalyst is slightly smaller than that of NH2-C2HN2S2-Au and CH3-C2HN2S2-Au, and it is uniformly distributed on the surface of the amorphous carbon powder without agglomeration.

[0065] Example 4

[0066] The preparation method of the working electrode in electrochemical testing and its application in the electrochemical reduction of carbon dioxide (15%) in flue gas to produce carbon monoxide include the following steps:

[0067] (1) Preparation of working electrode dispersion: Accurately weigh 10 mg of the catalysts NH2-C2HN2S2-Au, CH3-C2HN2S2-Au, SH-C2HN2S2-Au, and Naked-Au from Examples 1 to 3 above, and disperse them in 0.95 mL of ethanol and 0.05 mL of 5 wt% naphthol solution (at this time, the catalyst concentration is 10 mg / mL, and the amount of naphthol reagent is 5% of the total volume of the dispersion). After ultrasonic dispersion, the working electrode dispersion is obtained.

[0068] (2) Preparation of working electrode: Take 5 μL of the dispersion in step (1) (the amount of the dispersion is 0.5% of the total volume) and drop it onto the glassy carbon electrode (3 mm in diameter). After the solvent has completely evaporated, the electrode is dried to obtain the working electrode.

[0069] (3) Using the electrode in step (2) as the working electrode for the electrochemical reduction of carbon dioxide (15%) in flue gas to produce carbon monoxide, with a platinum wire as the counter electrode and a saturated calomel electrode as the reference electrode, the electrode is installed in a small electrochemical reactor to form a three-electrode system connected to an electrochemical workstation. In flue gas containing 15% carbon dioxide and 4% oxygen (the remainder is balanced with nitrogen) and argon-saturated 0.1 mol / mL potassium bicarbonate solution, a linear sweep voltammetry test is performed in the potential range of 0 to -1.0 V vs RHE to obtain the curve of the relationship between current density and electrode potential.

[0070] (4) Using the electrode in step (2) as the working electrode for the electrochemical reduction of carbon dioxide (15%) in flue gas to produce carbon monoxide, with a platinum wire as the counter electrode and a saturated calomel electrode as the reference electrode, the electrode is installed in a small electrochemical reactor to form a three-electrode system connected to an electrochemical workstation. In a 1 mol / mL potassium bicarbonate solution saturated with flue gas containing 15% carbon dioxide and 4% oxygen (the remainder is balanced with nitrogen), a constant potential electrolysis test is performed in the potential range of 0~-1.3V vs SCE to obtain the Faraday efficiency of carbon monoxide.

[0071] Figure 8 This is a curve showing the relationship between current density and voltage for the catalyst under flue gas and argon atmospheres. From... Figure 8 It can be seen that the NH2-C2HN2S2-Au catalyst exhibits a higher current density and a more positive peak potential under flue gas than under argon atmosphere. At a relatively small overpotential, the peak potential begins at approximately -0.15 V vs RHE (-0.7 V vs SCE), proving that the NH2-C2HN2S2-Au catalyst has the ability to reduce flue gas. Figure 8b. At the same electrode potential, the current density of the NH2-C2HN2S2-Au catalyst in flue gas is higher than that of the unmodified gold nanoparticle (Naked Au) catalyst, indicating that it has a better ability to reduce flue gas.

[0072] Figure 9 The figure shows the Faradaic efficiency of the electrocatalytic reduction of carbon dioxide to carbon monoxide from flue gas by NH2-C2HN2S2-Au, CH3-C2HN2S2-Au, SH-C2HN2S2-Au, and unmodified gold nanoparticles (Naked Au) catalysts, illustrating the change in the Faradaic efficiency of carbon monoxide with increasing electrode potential. The figure shows that the unmodified Naked Au catalyst exhibits virtually no ability to electrocatalyze the reduction of carbon monoxide from flue gas; at the optimal potential, the Faradaic efficiency is only 10.5%. The organically modified catalysts NH2-C2HN2S2-Au, CH3-C2HN2S2-Au, and SH-C2HN2S2-Au show significant ability to electrocatalyze the reduction of carbon dioxide to carbon monoxide from flue gas, achieving higher Faradaic efficiencies. As the electrode potential increased from -1.05V vs SCE to -1.35V vs SCE, the carbon monoxide Faradaic efficiency first increased and then decreased. At an electrode potential of -1.2V vs SCE, the carbon monoxide Faradaic efficiencies of the NH2-C2HN2S2-Au, CH3-C2HN2S2-Au, and SH-C2HN2S2-Au catalysts exceeded 40%, with the NH2-C2HN2S2-Au catalyst achieving the highest carbon monoxide Faradaic efficiency of 80.4%, demonstrating that gold nanoparticles modified with thiadiazole organic molecules have the ability to electrochemically capture and convert low-concentration CO2 in flue gas into CO.

[0073] Example 5

[0074] The preparation method of the working electrode in electrochemical testing and its application in the electrochemical reduction of carbon dioxide of different concentrations in flue gas to produce carbon monoxide include the following steps:

[0075] (1) Preparation of working electrode dispersion: Accurately weigh 10 mg of the catalyst NH2-C2HN2S2-Au in Example 1 above, disperse it in 0.95 mL of ethanol and 0.05 mL of 5 wt% naphthol solution (at this time, the catalyst concentration is 10 mg / mL, and the amount of naphthol reagent is 5% of the total volume of the dispersion), and obtain the working electrode dispersion after ultrasonic dispersion.

[0076] (2) Preparation of working electrode: Take 5 μL of the dispersion in step (1) (the amount of the dispersion is 0.5% of the total volume) and drop it onto the glassy carbon electrode (3 mm in diameter). After the solvent has completely evaporated, the electrode is dried to obtain the working electrode.

[0077] (3) Using the electrode in step (2) as the working electrode for the electrochemical reduction of carbon dioxide (8% and 75%) in flue gas to produce carbon monoxide, with platinum wire as the counter electrode and saturated calomel electrode as the reference electrode, the electrode is installed in a small electrochemical reactor to form a three-electrode system connected to an electrochemical workstation. In a 0.5 mol / mL potassium bicarbonate solution saturated with flue gas containing different concentrations of carbon dioxide (the rest is balanced with nitrogen), a constant potential electrolysis test is performed in the potential range of -1.2 V vs SCE to obtain the Faraday efficiency and current density of carbon monoxide.

[0078] Figure 10 This diagram illustrates the Faradaic efficiency of the NH2-C2HN2S2-Au catalyst in the electrocatalytic reduction of carbon dioxide to carbon monoxide from flue gas at different concentrations, depicting the change in the Faradaic efficiency of carbon monoxide with increasing carbon dioxide concentration. In potassium bicarbonate solutions saturated with flue gas of varying carbon dioxide concentrations, the NH2-C2HN2S2-Au catalyst prepared in Example 1 consistently demonstrated the ability to reduce flue gas to carbon monoxide. Even at a low carbon dioxide concentration of 8%, it exhibited a Faradaic efficiency exceeding 50% for carbon monoxide. When the carbon dioxide concentration exceeded 15%, the catalyst prepared in Example 1 achieved a Faradaic efficiency exceeding 80% for carbon monoxide. The Faradaic efficiency of carbon monoxide gradually stabilized with increasing carbon dioxide concentration, indicating that the NH2-C2HN2S2-Au catalyst prepared in Example 1 can enrich carbon dioxide at low concentrations and possesses saturated adsorption sites.

[0079] Therefore, it can be seen that the catalyst prepared in the examples can achieve the purpose of electrochemically capturing and converting carbon dioxide in flue gas to produce carbon monoxide under low carbon dioxide concentration atmosphere and low overpotential. It has excellent performance and has the application prospect of industrial development.

[0080] This invention combines thiadiazole-based redox-active amines with gold nanoparticles, resulting in a substance distinct from traditional thermal traps or electroreduction catalysts. Redox ligands capture carbon dioxide to form a transition state, where the carbon dioxide is pre-activated and can then be more effectively reduced to carbon monoxide by the gold nanoparticles, achieving integrated electrocapture and conversion. This thiadiazole-based organic molecule-modified gold nanoparticle catalyst has the structure defined as R-C2HN2S2-Au, where R = CH3, NH2, SH. This invention obtains a thiadiazole-based organic molecule-modified gold nanoparticle catalyst integrating electrocapture and conversion through a simple, mild, and reproducible wet chemical reduction method, exhibiting excellent performance in the electroreduction of flue gas to carbon monoxide. At the optimal potential, a carbon monoxide Faradaic efficiency exceeding 40% can be achieved in flue gas with different carbon dioxide concentrations (≥8%). Specifically, in flue gas with a 15% carbon dioxide concentration, the highest carbon monoxide Faradaic efficiency of 80.4% can be obtained. The use of this type of catalyst to electroreduce flue gas into carbon monoxide facilitates the direct utilization of industrial waste gas, has potential industrial development prospects, provides a feasible strategy for high-emission enterprises to achieve carbon reduction and negative carbon targets, and helps to promote the realization of the national "dual carbon" target.

[0081] The catalyst and related preparation method for the electrocatalytic reduction of carbon dioxide in flue gas to produce carbon monoxide, disclosed and proposed in this invention, have been described through preferred embodiments. Those skilled in the art can make modifications or appropriate alterations and combinations to the methods described without departing from the content, spirit, and scope of this invention to achieve the technical requirements of this invention. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the spirit, scope, and content of this invention.

Claims

1. The use of an integrated electro-capture and conversion catalyst for the electro-reduction of flue gas to carbon monoxide; characterized in that, The concentration of carbon dioxide gas in flue gas is 8-75%, the test potential interval of potentiostatic electrolysis experiment is-0.7--1.3 V vs SCE, the catalyst is a gold nanoparticle modified by a thiazole organic molecule, and the thiazole organic ligand is 2-amino-5-mercapto-1, 3, 4-thiazole.

2. Use according to claim 1, wherein the compound is ###0002### The preparation method of the integrated catalyst for electrocapture and conversion comprises the following steps: (1) the thiazole organic molecule and amorphous carbon powder are weighed and dispersed in ethylene glycol solvent to form a dispersion liquid; chloroauric acid is weighed and dissolved in ethylene glycol solvent to form a precursor solution; sodium borohydride is weighed and dissolved in ethylene glycol solvent to form a sodium borohydride solution; (2) the dispersion liquid in step (1) is dropped into the precursor solution under stirring, and placed in an ice bath for continuous stirring; (3) the sodium borohydride solution in step (1) is dropped into the mixed solution in step (2) under ice bath condition, and continuously stirred; (4) after the reaction is completed, centrifugal separation, washing and drying in a vacuum drying box are performed.

3. Use according to claim 2, wherein the compound is ###0002### The concentration of the thiazole organic molecule in the dispersion liquid in step (1) is 1.0 mg / mL-3.6 mg / mL.

4. The use according to claim 2, wherein the compound is ###0002### The concentration of chloroauric acid in the precursor solution in step (1) is 1.7-5.4 mg / mL.

5. The use according to claim 2, wherein the compound is ###0002### The concentration of sodium borohydride solution in step (1) is 20-50 mg / mL.

6. The use according to claim 2, wherein the compound is ###0002### The molar ratio of the thiazole organic molecule in the dispersion liquid to chloroauric acid in the precursor solution is 0.8:1-2:

1.

7. The use according to claim 2, wherein the compound is ###0002### The mass ratio of chloroauric acid to sodium borohydride in step (3) is 0.4:1-1.4:1.

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