A preparation method of a catalyst for efficiently electrocatalytically reducing nitrate
Patent Information
- Application Number
- CN202211616284.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-12-15
- Publication Date
- 2026-09-29
- Estimated Expiration
- 2042-12-15
AI Technical Summary
在众多的电催化材料中，铜基催化剂以其无毒无害、原料廉价和研究历史久而备受研究者们的青睐，然而其作为电催化剂在实际应用中仍然存在活性位点少、NO3-逐步去氧加氢过程反应热力学能垒高等问题，使得铜基催化剂的活性以及法拉第效应并没有达到工业化应用的要求
[0016]本发明所述的用于高效电催化还原硝酸根催化剂的制备方法在具体操作时，通过前驱体盐FeCl3·6H2O和CuI采用水热方法合成尺寸为2μm的CuFeO2纳米片，通过原位重构CuFeO2双金属氧化物纳米片，原位重构后吸附在Fe2O3基底上的Cu更加有利于NO3-底物的吸附、活化以及逐步加氢制NH3过程，催化剂的活性以及法拉第效应能够达到工业化应用的要求。需要说明的是，本发明具有原材料廉价、反应条件简单、活性高效以及适合进一步规模化生产的特点，另外，本发明通过电化学原位重构的方法，避免额外的化学还原，实现高效电催化硝酸根催化剂的构建。
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Figure CN116083944B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of energy catalysis technology and relates to a method for preparing a catalyst for the efficient electrocatalytic reduction of nitrate. Background Technology
[0002] In nature, the nitrogen cycle plays a crucial role in sustaining life. Ammonia synthesis is one of the world's largest industrial synthetic chemicals. Currently, ammonia synthesis is widely used in agriculture, chemical industry, medicine, and energy storage due to its high energy density, easy liquefaction, and convenient transportation. However, almost all industrial ammonia is currently synthesized through the Haber-Bosch process, which requires high-temperature and high-pressure reaction conditions, resulting in high energy consumption and large greenhouse gas emissions. Therefore, utilizing green, low-energy-consumption technologies to drive the nitrogen reduction synthesis of ammonia is a promising, clean, efficient, and sustainable ammonia synthesis route. Electrocatalytic reduction of NO3 at room temperature and pressure... - Solution-based ammonia synthesis technology has attracted the interest of researchers. Its principle involves the anode hole, driven by external electrons, to release OH-... - It is oxidized into oxygen and H2O, while NO3... - Hydrogen protons undergo a stepwise deoxygenation and hydrogenation process at the cathode surface, ultimately being reduced to ammonia by electrons. Among numerous electrocatalytic materials, copper-based catalysts are favored by researchers due to their non-toxicity, low cost of raw materials, and long research history. However, their application as electrocatalysts still faces challenges, including a limited number of active sites and NO3- condensation. - The high thermodynamic energy barrier of the stepwise deoxygenation and hydrogenation process prevents the activity and Faraday effect of copper-based catalysts from meeting the requirements for industrial application. Summary of the Invention
[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a catalyst for the high-efficiency electrocatalytic reduction of nitrate. The catalyst obtained by this method has the activity and Faraday effect required for industrial application.
[0004] To achieve the above objectives, the preparation method of the high-efficiency electrocatalytic reduction catalyst for nitrate ions according to the present invention includes the following steps:
[0005] 1) Hexagonal CuFeO2 nanosheet precursors were prepared by hydrothermal method using the precursor salt FeCl3·6H2O and CuI;
[0006] 2) The hexagonal CuFeO2 nanosheet precursor was dispersed in a mixture of Nafion and ethanol, ultrasonically dispersed, and then dropped onto a carbon paper substrate. After drying, an electrode was obtained. The electrode was placed in an H-type reactor for in-situ reconstruction to obtain a catalyst for the efficient electrocatalytic reduction of nitrate.
[0007] The specific operation of step 1) is as follows:
[0008] The precursor salts FeCl3·6H2O and CuI were added to water and stirred until homogeneous. KOH was added and the mixture was cooled to room temperature. The mixture was then transferred to a reaction vessel for hydrothermal reaction. After cooling naturally to room temperature, the mixture was centrifuged and washed to obtain a black precipitate. The black precipitate was then freeze-dried to obtain a hexagonal CuFeO2 nanosheet precursor.
[0009] The molar ratio of the precursor salt FeCl3·6H2O to CuI is 1:1.
[0010] The temperature during the hydrothermal reaction is 100-160℃, and the reaction time is 12-36h.
[0011] Washing is performed using deionized water and ethanol.
[0012] The electrolyte used in the in-situ reconstruction process is a mixture of 0.1M KNO3 and 1M KOH.
[0013] The negative potential during in-situ reconstruction is -0.3 to -0.8 V vs. RHE.
[0014] The in-situ reconstruction time is 20-60 minutes.
[0015] The present invention has the following beneficial effects:
[0016] In the specific operation of the preparation method for the highly efficient electrocatalytic reduction catalyst of nitrate described in this invention, CuFeO2 nanosheets with a size of 2 μm are synthesized by hydrothermal method using the precursor salts FeCl3·6H2O and CuI. The CuFeO2 bimetallic oxide nanosheets are then reconstructed in situ. After in-situ reconstruction, the Cu adsorbed on the Fe2O3 substrate is more conducive to NO3- reduction. - The adsorption, activation, and stepwise hydrogenation of the substrate to NH3 process demonstrate that the catalyst activity and Faraday effect meet the requirements for industrial application. It should be noted that this invention features inexpensive raw materials, simple reaction conditions, high activity, and suitability for further large-scale production. Furthermore, this invention utilizes an electrochemical in-situ reconstruction method to avoid additional chemical reduction, thereby achieving the construction of a highly efficient electrocatalytic nitrate catalyst. Attached Figure Description
[0017] Figure 1 The image shows the transmission electron microscope (TEM) characterization of the in-situ reconstructed CuFeO2 nanosheets in Example 1.
[0018] Figure 2 The images show the SEM characterization of CuFeO2 (ab) and Cu@Fe2O3 (cd) in Example 1.
[0019] Figure 3 The images show the TEM characterization of CuFeO2(a) and Cu@Fe2O3(bcd) in Example 1.
[0020] Figure 4 The Raman characterization diagrams of CuFeO2 (black) and Cu@Fe2O3 (green) in Example 1 are shown.
[0021] Figure 5 The image shows the transmission electron microscope (TEM) characterization of the in-situ reconstructed CuFeO2 nanosheets in Example 2.
[0022] Figure 6 The image shows the transmission electron microscope (TEM) characterization of the in-situ reconstructed CuFeO2 nanosheets in Example 3. Detailed Implementation
[0023] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion regarding the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.
[0024] The accompanying drawings show structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not drawn to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.
[0025] The preparation method of the high-efficiency electrocatalytic reduction catalyst for nitrate ions according to the present invention includes the following steps:
[0026] 1) A hexagonal CuFeO2 nanosheet precursor with a size of 2 μm was prepared by hydrothermal method;
[0027] The specific process is as follows: the precursor salts FeCl3·6H2O and CuI are added to 80mL of water at a molar ratio of 1:1, and the mixture is magnetically stirred for 15min to make it completely homogeneous. Then, 20mM KOH is added, and after cooling to room temperature, it is transferred to a 100mL reactor. The reactor is hydrothermally reacted at 100-160℃ for 12-36h. After naturally cooling to room temperature, the reactor is centrifuged at 10000rpm and washed with deionized water and ethanol to obtain a black precipitate. The black precipitate is then freeze-dried to obtain the hexagonal CuFeO2 nanosheet precursor.
[0028] 2) Preparation of in-situ reconstructed CuFeO2 bimetallic oxide nanosheet catalyst;
[0029] The specific process is as follows: 10 mg of hexagonal CuFeO2 nanosheet precursor is dispersed in a mixture of 50 μL Nafion and 950 μL ethanol, and ultrasonically dispersed for 30 min to obtain a dispersion. 50 μL of the dispersion is taken and dropped onto a 1 cm * 1 cm carbon paper substrate, and dried at 100 °C for 30 min to obtain an electrode. The electrode is placed in an H-type reactor, and in situ reconstruction is performed for 20-60 min at a negative potential of -0.3 to -0.8 V vs. RHE using 0.1 M KNO3 + 1 M KOH as the electrolyte, to obtain a catalyst for efficient electrocatalytic reduction of nitrate. Then, electrocatalytic reduction of NO3 is carried out at room temperature and pressure in a commercially available H-type reactor. - The ammonia production activity was tested using the indophenol blue spectrophotometric method (GB / T 18204.25-2000).
[0030] In this invention, the composition and structural characteristics of the CuFeO2 bimetallic oxide nanosheet precursor provide raw materials and structural support for the in-situ precipitation of Cu nanoparticles and the transformation of CuFeO2 to amorphous Fe2O3 crystalline phase. This allows more Cu nanoparticles to precipitate in situ on the catalyst surface. Furthermore, the formation of a tight heterojunction between Cu nanoparticles and amorphous Fe2O3 promotes charge migration between the two. Through the synergistic effect between Cu nanoparticles and amorphous Fe2O3, NO3 is significantly reduced. - The thermodynamic energy barrier of adsorption, activation, and stepwise hydrogenation to NH3 on the Cu@Fe2O3 surface promotes the breaking of N=O and the formation of NH3. x In addition to improving the hydrogenation process, this invention provides a larger specific surface area and more efficient adsorption and activation through in-situ reconstruction, thereby enhancing the electrocatalytic NO3-reaction process. - The activity of reducing to prepare ammonia.
[0031] Example 1
[0032] The preparation method of the high-efficiency electrocatalytic reduction catalyst for nitrate ions according to the present invention includes the following steps:
[0033] 1) A hexagonal CuFeO2 nanosheet precursor with a size of 2 μm was prepared by hydrothermal method;
[0034] The specific process is as follows: the precursor salts FeCl3·6H2O and CuI are added to 80mL of water at a molar ratio of 1:1, and the mixture is magnetically stirred for 15min to make it completely homogeneous. Then, 20mM KOH is added, and after cooling to room temperature, it is transferred to a 100mL reactor and hydrothermally reacted at 120℃ for 24h. After naturally cooling to room temperature, it is centrifuged at 10000rpm and then washed three times with deionized water and ethanol to obtain a black precipitate. The black precipitate is then freeze-dried to obtain the hexagonal CuFeO2 nanosheet precursor.
[0035] 2) Preparation of in-situ reconstructed CuFeO2 bimetallic oxide nanosheet catalyst;
[0036] The specific process is as follows: 10 mg of hexagonal CuFeO2 nanosheet precursor was dispersed in a mixture of 50 μL Nafion and 950 μL ethanol, and ultrasonically dispersed for 30 min to obtain a dispersion. 50 μL of the dispersion was taken and dropped onto a 1 cm * 1 cm carbon paper substrate, and dried at 100 °C for 30 min to obtain an electrode. The electrode was placed in an H-type reactor, and in-situ reconstruction was performed for 30 min at a negative potential of -0.6 V vs. RHE using 0.1 M KNO3 + 1 M KOH as the electrolyte to obtain a catalyst for the efficient electrocatalytic reduction of nitrate. Then, in a commercially available H-type reactor, a 0.1 M KNO3 + 1 M KOH electrolyte was used with an applied bias voltage of -0.6 V. vs.RHE Electrocatalytic NO3 under ambient temperature and pressure - The ammonia synthesis activity was tested using the indophenol blue spectrophotometric method (GB / T 18204.25-2000), and the ammonia production was quantified, reaching 1643 mmol / g. Cat ·h, Faraday efficiency remains at 99.1%.
[0037] Example 2
[0038] The preparation method of the high-efficiency electrocatalytic reduction catalyst for nitrate ions according to the present invention includes the following steps:
[0039] 1) A hexagonal CuFeO2 nanosheet precursor with a size of 2 μm was prepared by hydrothermal method;
[0040] The specific process is as follows: the precursor salts FeCl3·6H2O and CuI are added to 80mL of water at a molar ratio of 1:1, and the mixture is magnetically stirred for 15min to make it completely homogeneous. Then, 20mM KOH is added, and after cooling to room temperature, it is transferred to a 100mL reactor and hydrothermally reacted at 160℃ for 12h. After naturally cooling to room temperature, it is centrifuged at 10000rpm and then washed three times with deionized water and ethanol to obtain a black precipitate. The black precipitate is then freeze-dried to obtain the hexagonal CuFeO2 nanosheet precursor.
[0041] 2) Preparation of in-situ reconstructed CuFeO2 bimetallic oxide nanosheet catalyst;
[0042] The specific process is as follows: 10 mg of hexagonal CuFeO2 nanosheet precursor was dispersed in a mixture of 50 μL Nafion and 950 μL ethanol, and ultrasonically dispersed for 30 min to obtain a dispersion. 50 μL of the dispersion was taken and dropped onto a 1 cm * 1 cm carbon paper substrate, and dried at 100 °C for 30 min to obtain an electrode. The electrode was placed in an H-type reactor, and in-situ reconstruction was performed for 60 min at a negative potential of -0.3 V vs. RHE using 0.1 M KNO3 + 1 M KOH as the electrolyte to obtain a catalyst for the efficient electrocatalytic reduction of nitrate. Then, in a commercially available H-type reactor, a 0.1 M KNO3 + 1 M KOH electrolyte was used with an applied bias voltage of -0.6 V. vs.RHE Electrocatalytic NO3 under ambient temperature and pressure - The ammonia synthesis activity was tested using the indophenol blue spectrophotometric method (GB / T 18204.25-2000), and the ammonia production was quantified, reaching 1766 mmol / g. Cat ·h, Faraday efficiency remains at 99.5%.
[0043] Example 3
[0044] The preparation method of the high-efficiency electrocatalytic reduction catalyst for nitrate ions according to the present invention includes the following steps:
[0045] 1) A hexagonal CuFeO2 nanosheet precursor with a size of 2 μm was prepared by hydrothermal method;
[0046] The specific process is as follows: the precursor salts FeCl3·6H2O and CuI are added to 80mL of water at a molar ratio of 1:1, and the mixture is magnetically stirred for 15min to make it completely homogeneous. Then, 20mM KOH is added, and after cooling to room temperature, it is transferred to a 100mL reactor and hydrothermally reacted at 100℃ for 36h. After naturally cooling to room temperature, it is centrifuged at 10000rpm and then washed three times with deionized water and ethanol to obtain a black precipitate. The black precipitate is then freeze-dried to obtain the hexagonal CuFeO2 nanosheet precursor.
[0047] 2) Preparation of in-situ reconstructed CuFeO2 bimetallic oxide nanosheet catalyst;
[0048] The specific process is as follows: 10 mg of hexagonal CuFeO2 nanosheet precursor was dispersed in a mixture of 50 μL Nafion and 950 μL ethanol, and ultrasonically dispersed for 30 min to obtain a dispersion. 50 μL of the dispersion was taken and dropped onto a 1 cm*1 cm carbon paper substrate, and dried at 100 °C for 30 min to obtain an electrode. The electrode was placed in an H-type reactor, and in-situ reconstruction was performed for 20 min at a negative potential of -0.7 V vs. RHE using 0.1 M KNO3 + 1 M KOH as the electrolyte to obtain a catalyst for the efficient electrocatalytic reduction of nitrate. Then, in a commercially available H-type reactor, a 0.1 M KNO3 + 1 M KOH electrolyte was used with an applied bias voltage of -0.6 V. vs.RHE Electrocatalytic NO3 under ambient temperature and pressure - The ammonia synthesis activity was tested using the indophenol blue spectrophotometric method (GB / T 18204.25-2000), and the ammonia production was quantified, reaching 1593 mmol / g. Cat ·h, Faraday efficiency remains at 98.9%.
[0049] Example 4
[0050] The preparation method of the high-efficiency electrocatalytic reduction catalyst for nitrate ions according to the present invention includes the following steps:
[0051] 1) A hexagonal CuFeO2 nanosheet precursor with a size of 2 μm was prepared by hydrothermal method;
[0052] The specific process is as follows: the precursor salts FeCl3·6H2O and CuI are added to 80mL of water at a molar ratio of 1:1, and the mixture is magnetically stirred for 15min to make it completely homogeneous. Then, 20mM KOH is added, and after cooling to room temperature, it is transferred to a 100mL reactor and hydrothermally reacted at 100℃ for 12h. After naturally cooling to room temperature, it is centrifuged at 10000rpm and then washed with deionized water and ethanol to obtain a black precipitate. The black precipitate is then freeze-dried to obtain the hexagonal CuFeO2 nanosheet precursor.
[0053] 2) Preparation of in-situ reconstructed CuFeO2 bimetallic oxide nanosheet catalyst;
[0054] The specific process is as follows: 10 mg of hexagonal CuFeO2 nanosheet precursor was dispersed in a mixture of 50 μL Nafion and 950 μL ethanol, and ultrasonically dispersed for 30 min to obtain a dispersion. 50 μL of the dispersion was taken and dropped onto a 1 cm * 1 cm carbon paper substrate, and dried at 100 °C for 30 min to obtain an electrode. The electrode was placed in an H-type reactor, and in situ reconstruction was performed for 20 min at a negative potential of -0.3 V vs. RHE using 0.1 M KNO3 + 1 M KOH as the electrolyte to obtain a catalyst for efficient electrocatalytic reduction of nitrate. Then, electrocatalytic reduction of NO3 was carried out at room temperature and pressure in a commercially available H-type reactor. - The ammonia production activity was tested using the indophenol blue spectrophotometric method according to GB / T18204.25-2000.
[0055] Example 5
[0056] The preparation method of the high-efficiency electrocatalytic reduction catalyst for nitrate ions according to the present invention includes the following steps:
[0057] 1) A hexagonal CuFeO2 nanosheet precursor with a size of 2 μm was prepared by hydrothermal method;
[0058] The specific process is as follows: the precursor salts FeCl3·6H2O and CuI are added to 80mL of water at a molar ratio of 1:1, and the mixture is magnetically stirred for 15min to make it completely homogeneous. Then, 20mM KOH is added, and after cooling to room temperature, it is transferred to a 100mL reactor and hydrothermally reacted at 160℃ for 36h. After naturally cooling to room temperature, it is centrifuged at 10000rpm and then washed with deionized water and ethanol to obtain a black precipitate. The black precipitate is then freeze-dried to obtain the hexagonal CuFeO2 nanosheet precursor.
[0059] 2) Preparation of in-situ reconstructed CuFeO2 bimetallic oxide nanosheet catalyst;
[0060] The specific process is as follows: 10 mg of hexagonal CuFeO2 nanosheet precursor was dispersed in a mixture of 50 μL Nafion and 950 μL ethanol, and ultrasonically dispersed for 30 min to obtain a dispersion. 50 μL of the dispersion was taken and dropped onto a 1 cm * 1 cm carbon paper substrate, and dried at 100 °C for 30 min to obtain an electrode. The electrode was placed in an H-type reactor, and in situ reconstruction was performed for 60 min at a negative potential of -0.8 V vs. RHE using 0.1 M KNO3 + 1 M KOH as the electrolyte to obtain a catalyst for efficient electrocatalytic reduction of nitrate. Then, electrocatalytic reduction of NO3 was carried out at room temperature and pressure in a commercially available H-type reactor. - The ammonia production activity was tested using the indophenol blue spectrophotometric method according to GB / T18204.25-2000.
[0061] Example 6
[0062] The preparation method of the high-efficiency electrocatalytic reduction catalyst for nitrate ions according to the present invention includes the following steps:
[0063] 1) A hexagonal CuFeO2 nanosheet precursor with a size of 2 μm was prepared by hydrothermal method;
[0064] The specific process is as follows: the precursor salts FeCl3·6H2O and CuI are added to 80mL of water at a molar ratio of 1:1, and the mixture is magnetically stirred for 15min to make it completely homogeneous. Then, 20mM KOH is added, and after cooling to room temperature, it is transferred to a 100mL reactor and hydrothermally reacted at 110℃ for 15h. After naturally cooling to room temperature, it is centrifuged at 10000rpm and then washed with deionized water and ethanol to obtain a black precipitate. The black precipitate is then freeze-dried to obtain the hexagonal CuFeO2 nanosheet precursor.
[0065] 2) Preparation of in-situ reconstructed CuFeO2 bimetallic oxide nanosheet catalyst;
[0066] The specific process is as follows: 10 mg of hexagonal CuFeO2 nanosheet precursor was dispersed in a mixture of 50 μL Nafion and 950 μL ethanol, and ultrasonically dispersed for 30 min to obtain a dispersion. 50 μL of the dispersion was taken and dropped onto a 1 cm * 1 cm carbon paper substrate, and dried at 100 °C for 30 min to obtain an electrode. The electrode was placed in an H-type reactor, and in situ reconstruction was performed for 30 min at a negative potential of -0.4 V vs. RHE using 0.1 M KNO3 + 1 M KOH as the electrolyte to obtain a catalyst for the efficient electrocatalytic reduction of nitrate. Then, electrocatalytic reduction of NO3 was carried out at room temperature and pressure in a commercially available H-type reactor. - The ammonia production activity was tested using the indophenol blue spectrophotometric method according to GB / T18204.25-2000.
[0067] Example 7
[0068] The preparation method of the high-efficiency electrocatalytic reduction catalyst for nitrate ions according to the present invention includes the following steps:
[0069] 1) A hexagonal CuFeO2 nanosheet precursor with a size of 2 μm was prepared by hydrothermal method;
[0070] The specific process is as follows: the precursor salts FeCl3·6H2O and CuI are added to 80mL of water at a molar ratio of 1:1, and the mixture is magnetically stirred for 15min to make it completely homogeneous. Then, 20mM KOH is added, and after cooling to room temperature, it is transferred to a 100mL reactor and hydrothermally reacted at 150℃ for 30h. After naturally cooling to room temperature, it is centrifuged at 10000rpm and then washed with deionized water and ethanol to obtain a black precipitate. The black precipitate is then freeze-dried to obtain the hexagonal CuFeO2 nanosheet precursor.
[0071] 2) Preparation of in-situ reconstructed CuFeO2 bimetallic oxide nanosheet catalyst;
[0072] The specific process is as follows: 10 mg of hexagonal CuFeO2 nanosheet precursor was dispersed in a mixture of 50 μL Nafion and 950 μL ethanol, and ultrasonically dispersed for 30 min to obtain a dispersion. 50 μL of the dispersion was taken and dropped onto a 1 cm * 1 cm carbon paper substrate, and dried at 100 °C for 30 min to obtain an electrode. The electrode was placed in an H-type reactor, and in situ reconstruction was performed for 50 min at a negative potential of -0.7 V vs. RHE using 0.1 M KNO3 + 1 M KOH as the electrolyte to obtain a catalyst for the efficient electrocatalytic reduction of nitrate. Then, electrocatalytic reduction of NO3 was carried out at room temperature and pressure in a commercially available H-type reactor. - The ammonia production activity was tested using the indophenol blue spectrophotometric method according to GB / T18204.25-2000.
[0073] Example 8
[0074] The preparation method of the high-efficiency electrocatalytic reduction catalyst for nitrate ions according to the present invention includes the following steps:
[0075] 1) A hexagonal CuFeO2 nanosheet precursor with a size of 2 μm was prepared by hydrothermal method;
[0076] The specific process is as follows: the precursor salts FeCl3·6H2O and CuI are added to 80mL of water at a molar ratio of 1:1, and the mixture is magnetically stirred for 15min to make it completely homogeneous. Then, 20mM KOH is added, and after cooling to room temperature, it is transferred to a 100mL reactor and hydrothermally reacted at 140℃ for 25h. After naturally cooling to room temperature, it is centrifuged at 10000rpm and then washed with deionized water and ethanol to obtain a black precipitate. The black precipitate is then freeze-dried to obtain the hexagonal CuFeO2 nanosheet precursor.
[0077] 2) Preparation of in-situ reconstructed CuFeO2 bimetallic oxide nanosheet catalyst;
[0078] The specific process is as follows: 10 mg of hexagonal CuFeO2 nanosheet precursor was dispersed in a mixture of 50 μL Nafion and 950 μL ethanol, and ultrasonically dispersed for 30 min to obtain a dispersion. 50 μL of the dispersion was taken and dropped onto a 1 cm * 1 cm carbon paper substrate, and dried at 100 °C for 30 min to obtain an electrode. The electrode was placed in an H-type reactor, and in situ reconstruction was performed for 40 min at a negative potential of -0.5 V vs. RHE using 0.1 M KNO3 + 1 M KOH as the electrolyte to obtain a catalyst for efficient electrocatalytic reduction of nitrate. Then, electrocatalytic reduction of NO3 was carried out at room temperature and pressure in a commercially available H-type reactor. - The ammonia production activity was tested using the indophenol blue spectrophotometric method according to GB / T18204.25-2000.
[0079] This invention utilizes in-situ reconstruction of CuFeO2 bimetallic oxide nanosheets, resulting in Cu adsorbed on the Fe2O3 substrate after in-situ reconstruction, which is more conducive to NO3 adsorption. - The adsorption and activation of molecules enable this catalyst to achieve highly efficient electrocatalysis of NO3. - Performance of ammonia reduction. First, CuFeO2 nanosheets were hydrothermally synthesized using the precursor salts FeCl3·6H2O and CuI. During this process, KOH was added to promote crystallization, and the hydrothermal reaction temperature was optimized to control the catalyst morphology and growth. Then, the prepared CuFeO2 nanosheets were in-situ reconstructed in an alkaline electrolyte containing nitrate to construct a highly efficient Cu nanoparticle-supported amorphous Fe2O3 electrocatalyst for nitrate reduction. The prepared catalyst was then subjected to electrocatalytic NO3 reduction at room temperature and pressure in an H-type reactor. - Activity testing for ammonia reduction revealed that the catalyst's design strategy fully leverages the advantages of two-dimensional nanosheets—large specific surface area, numerous catalytic active sites, ease of supporting co-catalysts, and effective reduction of reaction initiation bias—while also utilizing the synergistic effect of Cu nanoparticles and amorphous Fe₂O₃ to effectively increase the proton yield required for nitrate reduction. Specifically, the reconstructed Cu metal sites enhance the reaction with NO₃⁻.- The adsorption, activation, and stepwise hydrogenation of molecules to NH3 significantly improve the ammonia synthesis activity and Faraday efficiency of the catalyst, which can promote the practical application of electrocatalytic ammonia synthesis.
[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.
Claims
1. A method for preparing a highly efficient electrocatalytic reduction catalyst for nitrate, characterized in that, Includes the following steps: 1) Hexagonal CuFeO2 nanosheet precursors were prepared by hydrothermal method using the precursor salt FeCl3·6H2O and CuI; 2) The hexagonal CuFeO2 nanosheet precursor was dispersed in a mixture of Nafion and ethanol, ultrasonically dispersed, and then dropped onto a carbon paper substrate and dried to obtain an electrode. The electrode was then placed in an H-type reactor for in-situ reconstruction to obtain a catalyst for the efficient electrocatalytic reduction of nitrate. The specific operation of step 1) is as follows: The precursor salts FeCl3·6H2O and CuI were added to water and stirred until homogeneous. KOH was added and the mixture was cooled to room temperature. The mixture was then transferred to a reaction vessel for hydrothermal reaction. After cooling to room temperature naturally, the mixture was centrifuged and washed to obtain a black precipitate. The black precipitate was then freeze-dried to obtain a hexagonal CuFeO2 nanosheet precursor. The molar ratio of the precursor salt FeCl3·6H2O to CuI is 1:1; The temperature during the hydrothermal reaction process is 100-160℃, and the hydrothermal reaction time is 12-36h; Wash with deionized water and ethanol; The electrolyte used in the in-situ reconstruction process was a mixture of 0.1 M KNO3 and 1 M KOH; The negative potential during in-situ reconstruction is -0.3 ~ -0.8 V vs. RHE; The in-situ reconstruction time is 20-60 min.