Cu / co bimetallic tandem organic-inorganic hybrid eutectic catalyst, and preparation method and application thereof
By constructing a Cu/Co bimetallic tandem organic-inorganic hybrid eutectic catalyst, the selectivity and stability issues of nitrate reduction to ammonia under acidic conditions were solved, achieving efficient nitrate reduction and inhibiting hydrogen evolution reaction, thus improving the stability and yield of the catalyst.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TIANJIN NORMAL UNIVERSITY
- Filing Date
- 2026-03-05
- Publication Date
- 2026-06-02
AI Technical Summary
Existing technologies for electrocatalytic reduction of nitrate to ammonia under acidic conditions exhibit poor selectivity, low yield, and poor catalyst stability. In particular, the Cu/Co bimetallic catalyst is prone to framework collapse in acidic systems, making it difficult to achieve efficient nitrate reduction and suppress hydrogen evolution reaction.
A Cu/Co bimetallic tandem organic-inorganic hybrid eutectic catalyst was constructed. Through the synergistic effect of coordination bonds, ionic bonds and multiple hydrogen bonds, the metal ratio was precisely controlled to form stable Cu/Co bimetallic active sites, which catalyze the reaction process from nitrate to nitrite and from nitrite to ammonia in series.
Ammonia production by nitrate reduction was achieved with high Faraday efficiency and high yield under acidic conditions, while suppressing the hydrogen evolution reaction. The catalyst exhibited ultra-high stability and high selectivity under strong acid conditions.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrocatalysis technology, and relates to a Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst and its preparation method, as well as electrocatalytic reduction of nitrate to ammonia under acidic conditions. Background Technology
[0002] Nitrogen oxides emitted from industrial flue gas, such as fossil fuel combustion, steel smelting, and waste incineration, contribute to acid rain, photochemical smog, and fine particulate matter formation, exacerbating air pollution and harming human health. Therefore, achieving sustained and in-depth reduction and efficient purification of nitrogen oxide emissions is of great significance. Meanwhile, ammonia (NH3) is an important chemical raw material. In agriculture, ammonia is a key component in the synthesis of nitrogen fertilizers, crucial for global food production. In industry, ammonia is used to manufacture explosives, plastics, fibers, and many other products. While the technology of selectively catalytically reducing NOx to nitrogen at a certain temperature using ammonia as a reducing agent has a wide range of applications and high potential, it is difficult to recover and utilize nitrogen resources from flue gas.
[0003] The traditional Haber process for ammonia production requires high temperature and pressure, which are harsh conditions and generate large amounts of carbon dioxide, causing severe environmental pollution. A wet process, which treats nitrogen oxides in flue gas to form nitrates and then uses green ammonia synthesis technology in an aqueous phase to electrocatalytically reduce nitrates into ammonia, is a highly valuable chemical. This process not only efficiently recovers precious nitrogen resources but also achieves comprehensive treatment and resource utilization of nitrogen oxides in flue gas, which is of great significance for promoting nitrogen cycling and sustainable development.
[0004] However, the NO3RR process (NO3 − + 8e − + 9H + → NH3 + 3H2O) involves a complex eight-electron, nine-proton transfer process and readily generates various byproducts (such as NO2). −Nitrate (NO, NH2OH, N2H4, etc.) readily undergoes hydrogen evolution reaction (HEP) under acidic conditions, resulting in poor selectivity and low yield for ammonia. Most reported copper-cobalt single-atom catalysts are based on neutral or alkaline systems, directly avoiding HEP. To challenge the electrocatalytic reduction of nitrate to ammonia in acidic systems, we constructed a copper-cobalt bimetallic catalyst. This catalyst achieves precise copper-cobalt pairing, catalyzing two reaction processes in series. The copper sites adsorb nitrate, promoting its conversion to nitrite, while the cobalt sites promote water splitting to generate active hydrogen, driving the conversion of nitrite to ammonia. The Cu / Co bimetallic catalyst effectively improves the competitiveness of the nitrate-to-ammonia reaction in acidic systems, effectively suppressing HEP and achieving high Faradaic efficiency and high yield. Furthermore, most current Cu / Co bimetallic catalysts used for the electrocatalytic reduction of nitrate to ammonia are metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), typically in neutral or alkaline systems. These materials are prone to framework collapse and poor stability under acidic conditions. Summary of the Invention
[0005] This invention addresses the problems of poor selectivity, low yield, and poor catalyst stability in the electrocatalytic reduction of nitrate to ammonia under acidic conditions. It constructs a Cu / Co bimetallic active site catalyst with ultra-high stability by combining the synergistic effects of coordination bonds, ionic bonds, and multiple hydrogen bonds, achieving highly efficient reduction of nitrate to ammonia under acidic conditions. Since the electrocatalytic reduction of nitrate to ammonia reaction can be divided into two continuous reactions: from NO3... − To NO2 − The slow two-electron reduction process, and from NO2 − The six-electron reduction process to NH3. Therefore, this invention realizes the tandem catalysis of two main reaction processes, in which the Cu site can adsorb nitrate ions and promote their conversion to nitrite ions, and the Co site promotes water splitting to generate active hydrogen to drive the conversion of nitrite ions to ammonia. Thus, under acidic conditions, the competitiveness of nitrate ions in ammonia synthesis is effectively improved, the hydrogen evolution reaction is inhibited, and high Faradaic efficiency and high yield are achieved.
[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: The first aspect of this invention relates to a Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst with electrocatalytic nitrate reduction performance, characterized in that the catalyst is formed by three chemical bonds: coordinate bonds, non-covalent bonds (hydrogen bonds), and ionic bonds, and exhibits strong stability under strongly acidic conditions. Single Cu, single Co, and Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalysts are precisely synthesized by controlling the molar ratio of organic ligand of formula I and metal nitrate; wherein the organic ligand is a compound of formula I.
[0007]
[0008] The second aspect of this invention relates to a method for preparing the organic ligand represented by Formula I as described in the first aspect, comprising the following steps: (1) 1,3-Dibromobenzene, 2,4-dimethoxyphenylboronic acid, or 2,5-dimethoxyphenylboronic acid were mixed in a 1:1 molar ratio and dissolved in dioxane and water. Then, 2 equivalents of potassium carbonate and 10% catalytic amount of Pd(dppf)Cl2 were added, and the mixture was heated and stirred under nitrogen protection for 12 hours. After the reaction was completed, the reaction solution was cooled to room temperature, the solvent was evaporated, and the mixture was extracted three times with dichloromethane and water. The organic phase was mixed with silica gel, and the crude product was separated and purified by column chromatography to obtain compound 1. The solvent ratio of dioxane to water was 5:1.
[0009] (2) Compound 1 and pinacol diborate were mixed in a 1:1 molar ratio and dissolved in dioxane. Then, 10% catalytic amount of Pd(dppf)Cl2 and 2 equivalents of potassium acetate were added. The mixture was heated and stirred under nitrogen protection for 12 hours. After the reaction was complete, the dioxane was removed by rotary evaporation and the product was extracted three times with dichloromethane and water. The crude product was purified by column chromatography to obtain compound 2.
[0010]
[0011] (3) Compound 2 and 6,6'-dibromo-2,2'-bipyridine were mixed in a molar ratio of 2:1 and dissolved in dioxane and water. Then, 4 equivalents of potassium carbonate and 10% catalytic amount of Pd(dppf)Cl2 were added, and the mixture was heated and stirred under nitrogen protection for 12 hours. After the reaction was complete, dioxane was removed by rotary evaporation, and the product was extracted three times with dichloromethane and water. The crude product was purified by column chromatography to obtain organic ligand I; the solvent ratio of dioxane to water was 5:1.
[0012]
[0013] The third aspect of this invention relates to the organic-inorganic hybrid eutectic catalysts of single Cu, single Co, and Cu / Co bimetals in series as described in the first aspect, comprising the following steps: (1) Preparation of single Cu metal-organic-inorganic hybrid eutectic catalyst: Organic ligand I and Cu(NO3)2 were mixed in a 1:1 molar ratio and dissolved in acetonitrile. The mixture was stirred at room temperature for 5 hours. After centrifugation, the mixture was washed five times with dichloromethane and dried at 60 °C overnight to obtain a single Cu metal-organic-inorganic hybrid eutectic catalyst material.
[0014] (2) Preparation of single-Co metal-organic-inorganic hybrid eutectic catalyst: Organic ligand I and Co(NO3)2 were mixed in a 1:1 molar ratio and dissolved in acetonitrile. The mixture was heated to 100 °C and stirred for 5 hours. After cooling to room temperature, the mixture was centrifuged, washed five times with dichloromethane, and dried overnight at 60 °C to obtain a single Co metal-organic-inorganic hybrid eutectic catalyst material.
[0015] (3) Preparation of Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst: Organic ligand I and Cu(NO3)2 were mixed in acetonitrile at a molar ratio of 4:1 and dissolved in acetonitrile, denoted as solution A. The mixture was stirred at room temperature for 5 hours. Then, Co(NO3)2 was dissolved in acetonitrile at a molar ratio of 1, denoted as solution B. Solution B was quickly poured into solution A, stirred at room temperature for 10 hours, centrifuged, washed five times with dichloromethane, and dried at 60 °C overnight to obtain the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst.
[0016] A third aspect of this invention provides a Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst. It is used for the electrocatalytic reduction of nitrate to ammonia, simultaneously achieving contaminant removal and ammonia synthesis under acidic conditions, particularly in the electrocatalytic reduction of nitrate to ammonia under acidic conditions.
[0017] This invention also discloses the catalytic performance of single Cu, single Co, and Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalysts for the electrocatalytic reduction of nitrate to ammonia under acidic conditions. Experimental results show that the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst exhibits high catalytic activity and high selectivity in the electrocatalytic reduction of nitrate to ammonia, achieving a Faradaic efficiency of 94.4% and an ammonia yield of 2.1 mmol / h at -1.6 V. -1 mg -1 Furthermore, due to the effect of multiple hydrogen bonds, the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst exhibits strong stability under strong acid conditions.
[0018] The Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst for nitrate reduction to ammonia disclosed in this invention has the following advantages compared with existing materials: 1. The Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst of this invention can be prepared by precisely controlling the ratio of metal ions. The preparation method is simple, low-cost, and highly reproducible, which greatly improves the uniformity of catalyst sites and achieves precise pairing of copper and cobalt. 2. The catalyst prepared by this invention is assembled by coordination bonds, ionic bonds and hydrogen bonds, and has a stable structure with 34 CH•••O hydrogen bond interactions, exhibiting ultra-high stability in an acidic system with pH=1. 3. The Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst of this invention can electrocatalyze the reduction of nitrate to ammonia. The precise pairing of copper and cobalt catalyzes the two main reaction processes in tandem. The copper sites adsorb nitrate, promoting its conversion to nitrite, while the cobalt sites promote water splitting to generate active hydrogen, driving the reduction of nitrite to ammonia. This enhances the competitiveness of the nitrate-to-ammonia reaction in an acidic system, effectively suppressing side reactions such as hydrogen evolution, and achieving high Faradaic efficiency and high yield. The third aspect of this invention relates to the single Cu, single Co, and Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalysts described in the first aspect, comprising the following steps: (1) Preparation of single Cu metal-organic-inorganic hybrid eutectic catalyst: Organic ligand I and Cu(NO3)2 were mixed in a 1:1 molar ratio and dissolved in acetonitrile. The mixture was stirred at room temperature for 5 hours. After centrifugation, the mixture was washed five times with dichloromethane and dried at 60 °C overnight to obtain a single Cu metal-organic-inorganic hybrid eutectic catalyst material.
[0019] (2) Preparation of single-Co metal-organic-inorganic hybrid eutectic catalyst: Organic ligand I and Co(NO3)2 were mixed in a 1:1 molar ratio and dissolved in acetonitrile. The mixture was heated to 100 °C and stirred for 5 hours. After cooling to room temperature, the mixture was centrifuged, washed five times with dichloromethane, and dried overnight at 60 °C to obtain a single Co metal-organic-inorganic hybrid eutectic catalyst material.
[0020] (3) Preparation of Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst: Organic ligand I and Cu(NO3)2 were mixed in acetonitrile at a molar ratio of 4:1 and dissolved in acetonitrile, denoted as solution A. The mixture was stirred at room temperature for 5 hours. Then, Co(NO3)2 was dissolved in acetonitrile at a molar ratio of 1, denoted as solution B. Solution B was quickly poured into solution A, stirred at room temperature for 10 hours, centrifuged, washed five times with dichloromethane, and dried at 60 °C overnight to obtain the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst.
[0021] A third aspect of this invention provides a Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst. It is used for the electrocatalytic reduction of nitrate to ammonia, simultaneously achieving contaminant removal and ammonia synthesis under acidic conditions, particularly in the electrocatalytic reduction of nitrate to ammonia under acidic conditions.
[0022] This invention also discloses the catalytic performance of single Cu, single Co, and Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalysts for the electrocatalytic reduction of nitrate to ammonia under acidic conditions. Experimental results show that the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst exhibits high catalytic activity and high selectivity in the electrocatalytic reduction of nitrate to ammonia, achieving a Faradaic efficiency of 94.4% and an ammonia yield of 2.1 mmol / h at -1.6 V. -1 mg -1 Furthermore, due to the effect of multiple hydrogen bonds, the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst exhibits strong stability under strong acid conditions.
[0023] The Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst for nitrate reduction to ammonia disclosed in this invention has the following advantages compared with existing materials: 1. The Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst of this invention can be prepared by precisely controlling the ratio of metal ions. The preparation method is simple, low-cost, and highly reproducible, which greatly improves the uniformity of catalyst sites and achieves precise pairing of copper and cobalt. 2. The catalyst prepared by this invention is assembled by coordination bonds, ionic bonds and hydrogen bonds, and has a stable structure with 34 CH•••O hydrogen bond interactions, exhibiting ultra-high stability in an acidic system with pH=1. 3. The Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst of this invention can electrocatalyze the reduction of nitrate to ammonia. The precise pairing of copper and cobalt catalyzes the two main reaction processes in series. The copper sites can adsorb nitrate and promote its conversion to nitrite, while the cobalt sites promote water splitting to generate active hydrogen, which drives the reduction of nitrite to ammonia. Under acidic conditions, this improves the competitiveness of the nitrate to ammonia synthesis reaction, effectively suppresses side reactions such as hydrogen evolution reaction, and achieves high Faraday efficiency and high yield. Attached Figure Description
[0024] Figure 1 The 1H NMR spectrum of organic ligand I prepared in Example 1; Figure 2 Crystal structure diagram of organic ligand I prepared in Example 1; Figure 3 The crystal structure diagram is shown for the single Cu metal-organic-inorganic hybrid eutectic catalyst material prepared in Example 3. Figure 4 The crystal structure diagram is shown for the single-Co metal-organic-inorganic hybrid eutectic catalyst material prepared in Example 3. Figure 5 Crystal structure diagram of the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst prepared in Example 3; Figure 6 The X-ray powder diffraction pattern for the stability test of the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst in Example 4; Figure 7 The linear sweep voltammogram of the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst for the electrocatalytic reduction of nitrate to ammonia in Example 5 is shown. Figure 8 The CA curves (chronoamperometry) of the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst in Example 5 for the electrocatalytic reduction of nitrate to ammonia at different voltages are shown. Figure 9 The figures show the Faraday efficiency and ammonia yield of the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst in Example 5 under different voltages for the electrocatalytic reduction of nitrate to ammonia. Detailed Implementation Plan The present invention will now be described through specific embodiments. Unless otherwise specified, all technical means used in this invention are methods well known to those skilled in the art. Furthermore, the embodiments should be understood as illustrative, not limiting the scope of the invention; the essence and scope of the invention are defined only by the claims. For those skilled in the art, various changes or modifications to the material composition and dosage in these embodiments without departing from the essence and scope of the invention are also within the scope of protection of this invention. All raw materials and reagents used in this invention are commercially available.
[0025] Example 1 Preparation of organic ligand I 10.8 g of compound 2 and 5 g of 6,6'-dibromo-2,2'-bipyridine were weighed and dissolved in 600 mL of dioxane / water (5:1). Then, 8.8 g of potassium carbonate and 1.2 g of Pd(dppf)Cl2 were added, and the mixture was heated and stirred under nitrogen protection under reflux for 12 hours. After the reaction was complete, the reaction solution was cooled to room temperature, and dioxane was removed by rotary evaporation. The mixture was then extracted three times with 300 mL of dichloromethane / water (2:1). The organic phase was stirred with silica gel, and the crude product was purified by column chromatography to obtain 8.1 g of organic ligand I. The results are as follows: Figure 1 , Figure 2 As shown, this indicates that organic ligand I was successfully synthesized.
[0026]
[0027] Example 2 (1) Preparation of single Cu metal-organic-inorganic hybrid eutectic catalyst material: Weigh 1 g of organic ligand I and 0.42 g of Cu(NO3)2 and mix them in 100 mL of acetonitrile. Stir at room temperature for 5 hours. Centrifuge, collect the lower precipitate and wash it five times with dichloromethane. Dry it overnight in a vacuum drying oven at 60 °C and grind it to obtain a single Cu metal-organic-inorganic hybrid eutectic catalyst material.
[0028] (2) Preparation of single-Co metal-organic-inorganic hybrid eutectic catalyst materials: Weigh 1 g of organic ligand I and 0.5 g of Co(NO3)2 and mix them in 100 mL of acetonitrile. Heat at 100 °C and stir for 10 hours. Cool to room temperature, centrifuge, collect the lower precipitate and wash it five times with dichloromethane. Dry it overnight in a vacuum drying oven at 60 °C and grind it to obtain a single Co metal-organic-inorganic hybrid eutectic catalyst material.
[0029] (3) Preparation of Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst: Weigh 1 g of organic ligand I and 0.1 g of Cu(NO3)2 and dissolve them in 100 mL of acetonitrile, which is recorded as solution A. Stir at room temperature for 5 hours. Then weigh 0.13 g of Co(NO3)2 and dissolve it in 20 mL of acetonitrile, which is recorded as solution B. Quickly pour solution B into solution A, stir at room temperature for 10 hours, centrifuge, collect the lower precipitate and wash it five times with dichloromethane. Dry it overnight in a vacuum drying oven at 60 °C and grind it to obtain the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst.
[0030] Example 3 (1) Preparation of single Cu metal-organic-inorganic hybrid eutectic catalyst crystals: Weigh 5 mg of organic ligand I and 2.1 mg of Cu(NO3)2, mix and dissolve in 2 mL of acetonitrile, diffuse in diethyl ether, and a single Cu metal-organic-inorganic hybrid eutectic catalyst material eutectic can be obtained in 1-2 days. It can form 42 C‒H•••O hydrogen bonds, as shown in the results. Figure 3 As shown.
[0031] (2) Preparation of single-Co metal-organic-inorganic hybrid eutectic catalyst crystals: Weigh 200 mg of organic ligand I and 100 mg of Co(NO3)2 and dissolve them in 40 mL of acetonitrile. Heat the mixture at 100 °C under nitrogen protection and stir under reflux for 12 hours. After the reaction is complete, cool to room temperature. Take 2 mL of the reaction solution into a sample vial and diffuse it in diethyl ether. A single-Co metal-organic-inorganic hybrid eutectic catalyst material eutectic can be obtained in 1-2 days. It can form 33 C‒H•••O hydrogen bonds. The results are as follows... Figure 4 As shown.
[0032] (3) Preparation of Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst crystals: Weigh 200 mg of organic ligand I and 20 mg of Cu(NO3)2 and dissolve them in 40 mL of acetonitrile. Stir at room temperature for 1 hour, and record this as solution A. Then weigh 26 mg of Co(NO3)2 and dissolve it in 5 mL of acetonitrile, and record this as solution B. Quickly pour solution B into solution A and stir at room temperature for 1 hour. Take 2 mL of the reaction solution into a sample vial and diffuse it in diethyl ether. After 1-2 days, a Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst eutectic can be obtained, which can form 34-fold C‒H•••O hydrogen bonds. The results are as follows. Figure 5 As shown.
[0033] Example 4 Stability testing of Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalysts The Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst crystals from Example 3 were immersed in an electrolyte at pH=1, and PXRD was measured every three days for a total of nine days. The results showed that the peak shape did not change, indicating that the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst has excellent stability. The results are as follows... Figure 6 As shown.
[0034] Example 5 Application of Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalysts in electrocatalytic nitrate reduction The electrocatalytic performance of the catalyst in the nitrate reduction reaction was tested using a three-electrode system in an H-type electrolytic cell on an electrochemical workstation. The electrolytic cell consisted of a cathode chamber and an anode chamber separated by a Nafion-211 proton exchange membrane. In the three-electrode system, the counter electrode was a Pt sheet electrode, the reference electrode was Hg / Hg₂Cl₂ (saturated KCl), and the working electrode was a platinum-carbon electrode. The electrolyte solution was 0.5 M Na₂SO₄ at pH = 1, and the nitrate source was 0.5 M NaNO₃. The electrolyte solution volumes in the cathode and anode chambers were both 10 mL. The catalyst was a Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst. The reaction time was 1 h. After the electrolysis reaction, the electrolyte composition was analyzed by UV-Vis spectrophotometry.
[0035] Modification of the working electrode: Weigh 9 mg of the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst prepared in Example 2 and 1 mg of conductive carbon black, mix them, add 475 μL of isopropanol and 25 μL of naphthol mixed solution, and sonicate for 30 s to prepare a uniform dispersion. Transfer 2 µL of the dispersion and drop it onto the electrode core, spreading it evenly, and let it air dry. Repeat the above operation twice.
[0036] Electrochemical tests were performed using a CHI760E electrochemical workstation. The catalytic activity of the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst was tested by measuring linear sweep voltammetry (LSV) curves with and without NaNO3 electrolyte solution. The current density in the NaNO3-containing catalytic system was higher than that in the NaNO3-free system, demonstrating that the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst has the effect of catalyzing the reduction of nitrate to ammonia. The results are as follows: Figure 7 As shown.
[0037] The catalytic performance of nitrate reduction to ammonia at different potentials was studied using chronoamperometry (CA), and current density-time curves were plotted. The results showed that the current density in 0.5 M NaNO3 electrolyte solution remained stable from -1.4 V to -1.8 V vs. SCE voltage, demonstrating that the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst possesses good catalytic stability. (See results below.) Figure 8 As shown.
[0038] The electrolytes after the reaction at different potentials were analyzed by ultraviolet spectrophotometry, and then analyzed by NO3. - Standard curve calculations for NH4+ in Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalysts + Yield and Faradaic efficiency. The Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst achieved a peak Faradaic efficiency of 94.4% at -1.6 V vs. SCE voltage, with an ammonia yield of 2.1 mmol / h. -1 mg -1 This indicates that the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst of the present invention exhibits excellent catalytic performance under acidic conditions. The results are as follows... Figure 9 As shown.
[0039] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst, characterized in that, The organic ligand is a compound of formula I as follows: .
2. The synthetic steps of the organic ligand bipyridine derivative shown in claim 1 are as follows: (1) 1,3-dibromobenzene and 2,4-dimethoxyphenylboronic acid were mixed in a molar ratio of 1:1.2 and dissolved in dioxane and water. Then potassium carbonate and Pd(dppf)Cl2 were added. The mixture was heated and stirred under nitrogen protection for 12 hours. After the reaction was complete, dioxane was removed by rotary evaporation. The crude product was extracted with dichloromethane and water and purified by column chromatography to obtain compound 1. ； (2) Compound 1 and pinacol diboronic acid ester were mixed in a molar ratio of 1:1.5 and dissolved in dioxane. Pd(dppf)Cl2 and potassium acetate were then added. The mixture was heated and stirred under nitrogen protection for 12 hours. After TLC monitoring confirmed that compound 1 had reacted completely, dioxane was removed by rotary evaporation and the crude product was extracted three times with dichloromethane and water to obtain compound 2. ； (3) Compound 2 and 6,6'-dibromo-2,2'-bipyridine were mixed in a molar ratio of 2:1 and dissolved in dioxane and water. Then potassium carbonate and Pd(dppf)Cl2 were added. The mixture was heated and stirred under nitrogen protection for 12 hours. After the reaction was complete, dioxane was removed by rotary evaporation. The product was extracted with dichloromethane and water. The crude product was separated and purified by column chromatography to obtain organic ligand I. 。 3. The method for preparing a Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst according to claim 1, characterized in that, This catalyst is assembled by co-coordinating organic ligand I with two metal salts, Cu(NO3)2 and Co(NO3)2, in an organic solvent through precise control of the component ratio. The driving forces are coordinate bonds, ionic bonds, and hydrogen bonds. The specific steps are as follows: (1) Mix organic ligand I and Cu(NO3)2, add acetonitrile to dissolve, and record as solution A. Stir at room temperature for 5 hours; Co(NO3)2 dissolves in acetonitrile, and record as solution B. (2) Quickly pour solution B into solution A, stir at room temperature for 10 hours, centrifuge, wash five times with dichloromethane, and dry at 60 °C overnight to obtain Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst material; The molar ratio of the mixture of organic ligand I, Cu(NO3)2 and Co(NO3)2 is 4:1:1; (3) Mix organic ligand I and Cu(NO3)2 and dissolve them in acetonitrile. Stir at room temperature for 1 hour and record as solution C. Then dissolve Co(NO3)2 in acetonitrile and record as solution D. Pour solution C into solution D and stir at room temperature for 1 hour. Take the reaction solution into a sample bottle and diffuse it in diethyl ether. Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst crystals can be obtained in 1-2 days.
4. The method for preparing the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst according to claim 3, characterized in that, The catalyst is stable for more than 9 days under acidic conditions at pH = 1.
5. The method for preparing a Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst according to claim 3, characterized in that, By introducing a single Co atom next to a single Cu atom, a diatomic catalyst capable of relay catalysis is formed.
6. The application of the Cu / Co bimetallic tandem organic-inorganic hybrid eutectic catalyst of claim 1 in the electrocatalytic reduction of nitrate to ammonia, simultaneously achieving pollutant removal and ammonia synthesis under acidic conditions.