A rare earth cerium doped copper / molybdenum dioxide heteromaterial, a preparation method and application thereof
By preparing rare earth cerium-doped copper/molybdenum dioxide heterogeneous materials, the problem of low selectivity of single copper-centered materials in electrochemical nitrate reduction to ammonia synthesis was solved, and the catalytic performance of efficient nitrate reduction to ammonia was improved.
Patent Information
- Application Number
- CN202411962156.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-10-21
- Estimated Expiration
- 2044-12-30
AI Technical Summary
A single copper-centered material is difficult to provide the active adsorbed hydrogen atoms required for the catalytic reaction, resulting in low selectivity for electrochemical nitrate reduction to synthesize ammonia. In the existing technology, rare earth elements are rarely used in copper-based materials.
A metal-organic precursor-mediated strategy was adopted to prepare rare earth cerium-doped copper/molybdenum dioxide heterogeneous materials. Through co-precipitation method and high-temperature calcination under inert atmosphere protection, Ce-Cu/MoO2 nanomaterials with pomegranate seed-like structure were formed. Rare earth cerium was introduced to regulate the electronic state of the copper center and serve as the center of active hydrogen.
Under alkaline conditions, the Ce-Cu/MoO2 material exhibits high ammonia production rate and Faradaic efficiency, improving the catalytic performance.
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Figure CN119771448B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of nanomaterial preparation, and in particular relates to a rare earth cerium-doped copper / molybdenum dioxide heterogeneous material and its preparation and application. Background Art
[0002] The ammonia industry forms the foundation of modern agriculture and human society. Ammonia (NH3) is also considered the future hydrogen storage fuel, with a hydrogen storage capacity of up to 17.6wt%. Currently, ammonia production worldwide is achieved through the traditional Haber-Bosch process, which requires high temperature and high pressure reaction conditions, consumes a lot of energy, and releases large amounts of carbon dioxide. Therefore, using electricity generated by renewable energy sources such as solar, wind, and tidal energy to synthesize ammonia through electrochemical catalysis by reducing nitrates is considered a new technology for future green ammonia synthesis.
[0003] Electrochemical nitrate reduction involves a complex process involving eight electrons and nine protons, with numerous intermediates and products. Therefore, developing high-performance electrocatalytic materials for the efficient and selective reduction of nitrate to ammonia is of great significance. Currently, copper-based materials have garnered significant attention in the field of nitrate reduction to ammonia synthesis. However, the single copper center is unable to provide the active adsorbed hydrogen atoms required for the catalytic reaction, making the active hydrogen-mediated reduction pathway difficult to achieve and resulting in low ammonia selectivity.
[0004] Rare earth elements and their compounds are important strategic resources, widely used in a variety of fields, including aviation, aerospace, information technology, electronics, energy, transportation, and healthcare. The "Rare Earth Management Regulations," which came into effect on October 1, 2024, explicitly encourage and support the research and development and application of new technologies, processes, products, materials, and equipment in the rare earth industry. Cerium oxide, with its abundant reserves, low price, and excellent stability, has been extensively studied in the catalysis field. At present, a large number of studies have introduced cerium oxide or rare earth cerium ions into active materials to regulate the surface microstructure and electronic structure of active centers of active materials, thereby improving their catalytic performance in electrochemical water splitting reactions (Appl. Catal. B: Environ. 2024, 343, 123560, Small 2022, 18, 2106592, Chem. Eng. J. 2023, 460, 141119, Inorg. Chem. 2024, 63, 16824 Adv. Energy Mater. 2024, DOI: 10.1002 / aenm.202402923, Angew. Chem. Int. Ed. 2024, DOI: 10.1002 / anie.202415306).
[0005] Given the difficulty of undergoing an active hydrogen-mediated reduction pathway in single copper-centered materials as described above, most existing research and technologies use transition metal nickel or cobalt centers to optimize the active hydrogen-mediated reduction pathway, which to some extent promotes the catalytic process. It is necessary to introduce new centers to optimize the structure to achieve further improvements in catalytic performance. Currently, there are few studies on the introduction of rare earths into active copper-based materials. Therefore, the present invention adopts a metal-organic precursor-mediated strategy to prepare a rare earth cerium-doped copper / molybdenum dioxide heterogeneous material, which has crucial application value for the electrochemical reduction of nitrates to synthesize ammonia. Summary of the Invention
[0006] The purpose of the present invention is to provide a rare earth cerium-doped copper / molybdenum dioxide heterogeneous material and its preparation method and application. When the material of the present invention is used as a catalyst, it exhibits a high ammonia production rate and Faradaic efficiency for nitrate reduction to synthesize ammonia under alkaline conditions.
[0007] In order to achieve the above object, the present invention adopts the following technical solutions:
[0008] The present invention first provides a method for preparing a rare earth cerium-doped copper / molybdenum dioxide heterogeneous material, comprising:
[0009] Step 1: dissolving rare earth cerium salt, copper salt, molybdenum salt and coordination modulator in water, stirring evenly to obtain a metal salt solution, pouring the organic ligand solution into the metal salt solution, stirring evenly to obtain rare earth cerium doped metal organic precursor nanomaterial;
[0010] Step 2: Under the protection of an inert atmosphere, the rare earth cerium-doped metal organic precursor nanomaterial obtained in step 1 is placed in a tube furnace and calcined to obtain a rare earth cerium-doped copper / molybdenum dioxide heterogeneous material.
[0011] Preferably, the molar ratio of the rare earth cerium salt, copper salt, molybdenum salt and coordination modulator in step 1 is (0.5-5): (40-60): (6-15): (20-40), and the molar ratio of the copper salt to the organic ligand is (40-60): (30-50).
[0012] Preferably, the cerium salt is cerium nitrate, cerium chloride or cerium acetate.
[0013] Preferably, the copper salt is copper nitrate, copper chloride or copper acetate.
[0014] Preferably, the molybdenum salt is ammonium heptamolybdate or phosphomolybdic acid.
[0015] Preferably, the coordination modulator is L-aspartic acid, L-alanine or L-glutamic acid.
[0016] Preferably, the organic ligand is trimesic acid, terephthalic acid or thiophenedicarboxylic acid.
[0017] Preferably, the calcination temperature in step 2 is 600° C. to 900° C., and the calcination time is 1 to 4 hours.
[0018] The present invention also provides a rare earth cerium-doped copper / molybdenum dioxide heterogeneous material obtained by the above preparation method, wherein the material has a pomegranate seed-like structure.
[0019] The present invention also provides the use of the rare earth cerium-doped copper / molybdenum dioxide heterogeneous material as a catalyst in the synthesis of ammonia by nitrate reduction.
[0020] Beneficial effects of the present invention
[0021] The present invention provides a rare earth cerium doped copper / molybdenum dioxide heterogeneous material and its preparation method and application. The material of the present invention is prepared by a coprecipitation method under the regulation of a coordination modulator to prepare a rare earth cerium doped copper molybdenum-based metal organic precursor, and then a high-temperature calcination method under the protection of an inert atmosphere is used to prepare a cerium doped copper / molybdenum dioxide heterogeneous material (Ce-Cu / MoO2). The introduction of rare earth cerium in the present invention can regulate the electronic state of the copper center in the material. At the same time, cerium can serve as a center for water dissociation to produce active hydrogen, thereby forming a dual-center catalytic material and improving the catalytic performance of the material. The Ce-Cu / MoO2 nanomaterial prepared by the present invention has a unique pomegranate seed-like structure. When used as a catalyst, it exhibits a high ammonia production rate and Faraday efficiency for nitrate reduction to synthesize ammonia under alkaline conditions. In addition, the preparation method is simple, the raw materials are easily available, and the practical value is high, which is of great significance for the design, preparation and application of catalysts. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a scanning electron microscope image of the cerium-doped copper-molybdenum-based metal organic precursor prepared in Example 1.
[0023] Figure 2 This is the XRD pattern of Ce-Cu / MoO2 nanomaterial in Example 1.
[0024] Figure 3 These are the polarization curves of Ce-Cu / MoO2 nanomaterials in Example 5 under different electrolytes.
[0025] Figure 4 This is the XPS graph of Cu in Ce-Cu / MoO2 and Cu / MoO2 nanomaterials in Example 6.
[0026] Figure 5 The catalytic performance of Ce-Cu / MoO2 and Cu / MoO2 nanomaterials tested in Example 7. DETAILED DESCRIPTION
[0027] The present invention first provides a method for preparing a rare earth cerium-doped copper / molybdenum dioxide heterogeneous material, comprising:
[0028] Step 1: dissolving a rare earth cerium salt, a copper salt, a molybdenum salt, and a coordination modulator in water, controlling the molar ratio of the four to preferably be 0.5-5:40-60:6-15:20-40, and stirring evenly at room temperature to obtain a metal salt solution; dissolving an organic ligand in a solvent, preferably ethanol, controlling the molar ratio of the copper salt to the organic ligand to preferably be 40-60:30-50, pouring the organic ligand solution into the above-mentioned metal salt solution, stirring evenly, the stirring time is preferably 6-14 hours, and the obtained product is centrifuged and washed with deionized water and ethanol respectively, and then dried, the drying temperature is preferably 50-80°C, the drying time is preferably 8-24 hours, more preferably 8-12 hours, to obtain a rare earth cerium doped metal organic precursor nanomaterial;
[0029] The cerium salt is preferably cerium nitrate, cerium chloride or cerium acetate; the copper salt is preferably copper nitrate, copper chloride or copper acetate; the molybdenum salt is preferably ammonium heptamolybdate or phosphomolybdic acid;
[0030] The coordination modulator is preferably L-aspartic acid, L-alanine or L-glutamic acid. The organic ligand is preferably trimesic acid, terephthalic acid or thiophenedicarboxylic acid.
[0031] Step 2: Place the above-mentioned cerium-doped metal organic precursor nanomaterial in a tubular furnace and calcine it under the protection of an inert atmosphere. The calcination temperature is preferably 600-900°C, more preferably 700-800°C, the calcination time is preferably 1-4h, more preferably 2-3h, and the heating rate is preferably 2-6°C / min to obtain cerium-doped copper / molybdenum dioxide (Ce-Cu / MoO2) heterogeneous nanomaterials.
[0032] The present invention also provides a rare earth cerium-doped copper / molybdenum dioxide heterogeneous material obtained by the above preparation method, wherein the material has a pomegranate seed-like structure.
[0033] The present invention also provides the use of the rare earth cerium-doped copper / molybdenum dioxide heterogeneous material as a catalyst in the synthesis of ammonia by nitrate reduction.
[0034] The specific implementation scheme of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.
[0035] Example 1
[0036] Preparation of Cerium-doped Copper / MoO2 Heterogeneous Nanomaterials
[0037] Cu(CH3COO)2·H2O (285 mg), Ce(CH3COO)3·xH2O (23.8 mg), L-glutamic acid (110 mg), and hydrated phosphomolybdic acid (450 mg) were dissolved in water (60 mL) and stirred at room temperature for 30 minutes to form a metal salt solution. Trimesic acid (211 mg) was dissolved in ethanol (60 mL) and stirred at room temperature for 10 minutes to form an organic ligand solution. The two solutions were then mixed and stirred at room temperature for 14 hours. The resulting product was then centrifuged with H2O and ethanol and dried at 60°C for 12 hours to obtain a cerium-doped copper-molybdenum-based metal organic precursor nanomaterial.
[0038] The above-mentioned cerium-doped copper-molybdenum-based metal organic precursor nanomaterial (200 mg) was placed in a porcelain boat and placed in a tube furnace, and was calcined at high temperature under argon atmosphere at a calcination temperature of 700°C, a heating rate of 2°C / min, and a calcination time of 2h to obtain Ce-Cu / MoO2 nanomaterial.
[0039] The morphology of the prepared cerium-doped copper-molybdenum-based metal organic precursor was characterized by scanning electron microscopy. Figure 1 As shown in the figure, it presents a smooth octahedral morphology with a particle size of about 400nm. At the same time, the interior presents nanoparticles similar to pomegranate seeds.
[0040] The phase of the prepared Ce-Cu / MoO2 was characterized by X-ray diffraction. Figure 2 As shown in FIG, the obtained Ce-Cu / MoO2 nanomaterial has the crystalline phases of Cu element and MoO2.
[0041] Example 2
[0042] Preparation of Cerium-doped Copper / MoO2 Heterogeneous Nanomaterials
[0043] Cu(NO3)2·3H2O (342 mg), Ce(NO3)3·6H2O (26.6 mg), L-aspartic acid (55 mg), and ammonium heptamolybdate (492 mg) were dissolved in water (60 mL) and stirred at room temperature for 30 minutes to form a metal salt solution. Terephthalic acid (166 mg) was dissolved in ethanol (60 mL) and stirred at room temperature for 10 minutes to form an organic ligand solution. The two solutions were then mixed and stirred at room temperature for 8 hours. The resulting product was then centrifuged with H2O and ethanol and dried at 60°C for 8 hours to obtain a cerium-doped copper-molybdenum-based metal organic precursor nanomaterial.
[0044] The above-mentioned cerium-doped copper-molybdenum-based metal organic precursor nanomaterial (180 mg) was placed in a porcelain boat and placed in a tube furnace, and was calcined at high temperature under argon atmosphere at a calcination temperature of 800°C, a heating rate of 5°C / min, and a calcination time of 3 h to obtain Ce-Cu / MoO2 nanomaterial.
[0045] Example 3
[0046] Preparation of Cerium-doped Copper / MoO2 Heterogeneous Nanomaterials
[0047] CuCl2·2H2O (243 mg), CeCl3·7H2O (22.8 mg), L-alanine (100 mg), and hydrated phosphomolybdic acid (600 mg) were dissolved in water (60 mL) and stirred at room temperature for 30 minutes to form a metal salt solution. Terephthalic acid (250 mg) was dissolved in ethanol (60 mL) and stirred at room temperature for 10 minutes to form an organic ligand solution. The two solutions were then mixed and stirred at room temperature for 10 hours. The resulting product was then centrifuged with H2O and ethanol and dried at 70°C for 12 hours to obtain a cerium-doped copper-molybdenum-based metal organic precursor nanomaterial.
[0048] The above-mentioned cerium-doped copper-molybdenum-based metal organic precursor nanomaterial (240 mg) was placed in a porcelain boat and placed in a tube furnace, and was calcined at high temperature under argon atmosphere at a calcination temperature of 900°C, a heating rate of 2°C / min, and a calcination time of 2h to obtain Ce-Cu / MoO2 nanomaterial.
[0049] Example 4
[0050] Preparation of Cerium-doped Copper / MoO2 Heterogeneous Nanomaterials
[0051] Cu(CH3COO)2·H2O (305 mg), Ce(NO3)3·6H2O (29.6 mg), L-aspartic acid (128 mg), and hydrated phosphomolybdic acid (480 mg) were dissolved in water (60 mL) and stirred at room temperature for 30 minutes to form a metal salt solution. Thiophenedicarboxylic acid (220 mg) was dissolved in ethanol (60 mL) and stirred at room temperature for 10 minutes to form an organic ligand solution. The two solutions were then mixed and stirred at room temperature for 14 hours. The resulting product was then centrifuged with H2O and ethanol and dried at 70°C for 12 hours to obtain a cerium-doped copper-molybdenum-based metal organic precursor nanomaterial.
[0052] The above-mentioned cerium-doped copper-molybdenum-based metal organic precursor nanomaterial (160 mg) was placed in a porcelain boat and placed in a tube furnace, and was calcined at high temperature under an argon atmosphere at a calcination temperature of 650°C, a heating rate of 2°C / min, and a calcination time of 4 h to obtain Ce-Cu / MoO2 nanomaterial.
[0053] Comparative Example 1
[0054] Preparation of copper / molybdenum dioxide heterogeneous nanomaterials
[0055] Cu(CH3COO)2·H2O (285 mg), L-glutamic acid (110 mg), and hydrated phosphomolybdic acid (450 mg) were dissolved in water (60 mL) and stirred at room temperature for 30 minutes to form a metal salt solution. Trimesic acid (211 mg) was dissolved in water (60 mL) and stirred at room temperature for 10 minutes to form an organic ligand solution. The two solutions were then mixed and stirred at room temperature for 14 hours. The resulting product was then centrifuged with H2O and ethanol and dried at 60°C for 12 hours to obtain a copper-molybdenum-based metal organic precursor nanomaterial.
[0056] The copper-molybdenum-based metal organic precursor nanomaterial (200 mg) was placed in a porcelain boat and placed in a tube furnace. It was calcined at 700°C, a heating rate of 2°C / min, and a calcination time of 2 hours under an argon atmosphere to obtain a Cu / MoO2 nanomaterial.
[0057] Example 5
[0058] Catalytic performance test of Ce-Cu / MoO2 nanomaterials
[0059] The working electrode preparation process is as follows: weigh 5 mg of the catalyst prepared in Example 1 into a 2 mL centrifuge tube, then add 250 μL each of H2O and isopropanol, and finally add 15 μL of Nafion solution, mix well and ultrasonicate for 30 minutes. Take 10 μL of the prepared ink and evenly apply it on 0.25 cm × 0.25 cm carbon paper and dry it at room temperature. Place the prepared electrode in an electrolytic cell, with the platinum sheet as the counter electrode, the Ag / AgCl electrode as the reference electrode, and 1 M KOH + 0.1 M KNO3 as the electrolyte. Use an electrochemical workstation and use linear sweep voltammetry to test, as shown in Figure 2. Figure 3 As shown in Figure 3, according to the current density of the polarization curves in pure 1M KOH and 1M KOH+0.1M KNO3, it can be seen that the introduction of Ce has obvious catalytic activity for nitrate reduction.
[0060] Example 6
[0061] Chemical structure test of Ce-Cu / MoO2 and Cu / MoO2 nanomaterials
[0062] It was characterized by XPS, such as Figure 4 As shown in the figure, the introduction of Ce changes the electronic structure of the Cu center inside the catalytic material. Therefore, doping rare earth cerium into copper-based materials through this synthesis method is of great significance for regulating the material structure and improving the electrocatalytic performance.
[0063] Example 7
[0064] Catalytic Performance of Ce-Cu / MoO2 and Cu / MoO2 Nanomaterials
[0065] The IT test was performed at a potential of -0.4V and -0.5V (relative to the reversible hydrogen electrode), and the color was developed by the indophenol blue method for quantitative analysis. Figure 5 As shown in Figure 2, the yield and Faradaic efficiency of Ce-Cu / MoO2 nanomaterials for synthesizing ammonia are 20736.33 μg h -1 mg cat. -1 and 94.15%. The catalytic performance of Ce-Cu / MoO2 nanomaterials is significantly higher than that of Cu / MoO2 nanomaterials without cerium doping.
Claims
1. A method for preparing rare earth cerium-doped copper / molybdenum dioxide heterogeneous material, characterized in that: include: Step 1: dissolving rare earth cerium salt, copper salt, molybdenum salt and coordination modulator in water, stirring evenly to obtain a metal salt solution, pouring the organic ligand solution into the metal salt solution, stirring evenly to obtain rare earth cerium doped metal organic precursor nanomaterial; Step 2: Under inert atmosphere, calcining the rare earth cerium-doped metal organic precursor nanomaterial obtained in step 1 in a tube furnace to obtain a rare earth cerium-doped copper / molybdenum dioxide heterogeneous material; The coordination modulator is L-aspartic acid, L-alanine or L-glutamic acid; The organic ligand is trimesic acid, terephthalic acid or thiophenedicarboxylic acid.
2. The method for preparing a rare earth cerium-doped copper / molybdenum dioxide heterogeneous material according to claim 1, characterized in that: The molar ratio of the rare earth cerium salt, copper salt, molybdenum salt, and coordination modulator in step 1 is (0.5-5): (40-60): (6-15): (20-40), and the molar ratio of the copper salt to the organic ligand is (40-60): (30-50).
3. The method for preparing a rare earth cerium-doped copper / molybdenum dioxide heterogeneous material according to claim 1, characterized in that: The cerium salt is cerium nitrate, cerium chloride or cerium acetate.
4. The method for preparing a rare earth cerium-doped copper / molybdenum dioxide heterogeneous material according to claim 1, characterized in that: The copper salt is copper nitrate, copper chloride or copper acetate.
5. The method for preparing a rare earth cerium-doped copper / molybdenum dioxide heterogeneous material according to claim 1, characterized in that: The molybdenum salt is ammonium heptamolybdate or phosphomolybdic acid.
6. The method for preparing a rare earth cerium-doped copper / molybdenum dioxide heterogeneous material according to claim 1, characterized in that: The calcination temperature in step 2 is 600° C. to 900° C., and the calcination time is 1 to 4 hours.
7. The rare earth cerium-doped copper / molybdenum dioxide heterogeneous material obtained by the preparation method according to claim 1, characterized in that: The material has a pomegranate seed-like structure.
8. Use of the rare earth cerium-doped copper / molybdenum dioxide heterogeneous material according to claim 7 as a catalyst in the synthesis of ammonia by reduction of nitrate.