Pd cluster modified In2O3 composite material as well as preparation method and application thereof
The preparation of In2O3 composite materials modified with Pd clusters solved the problem of balancing activation and hydrogenation processes in the nitrate reduction reaction of existing catalysts, achieving highly efficient catalytic activity and stability for the conversion of nitrate to ammonia, and is applicable to the field of electrocatalysts.
Patent Information
- Application Number
- CN202511863367.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-11
- Publication Date
- 2026-02-10
AI Technical Summary
Existing catalysts struggle to simultaneously address nitrate activation and hydrogenation processes in the electrocatalytic nitrate reduction reaction, resulting in low Faraday efficiency and selectivity for ammonia. Traditional materials such as In2O3 exhibit weak hydrogen activation capabilities, while Pd-based materials are prone to initiating hydrogen evolution reactions, leading to electron waste.
By preparing a composite material of In2O3 modified with Pd clusters, an in-situ reduction-heat treatment method was adopted. The palladium species were stabilized by polyvinylpyrrolidone, and the palladium ions were reduced by sodium borohydride to form uniformly distributed Pd clusters. The electronic interactions between the supports were optimized, and bifunctional active sites were constructed.
This study achieved a synergistic promotion of nitrate activation and hydrogenation processes, improving the catalytic activity and stability of electrocatalytic nitrate reduction to ammonia synthesis, and has promising application prospects.
Smart Images
Figure CN121496470A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of electrocatalysts and electrochemical environmental governance, and in particular to a Pd cluster modified In2O3 composite material, a preparation method and application thereof. BACKGROUND
[0002] Nitrate is a common nitrogen pollutant in industrial, agricultural and domestic wastewater, which can easily lead to water eutrophication and threaten human health. Common treatment technologies such as physical adsorption, ion exchange, biological denitrification and chemical reduction have low efficiency, high energy consumption and are prone to secondary pollution, which are difficult to be widely promoted.
[0003] In recent years, electrocatalytic nitrate reduction reaction (NO3RR) has attracted much attention because it can efficiently convert nitrate into high-value-added ammonia at room temperature and atmospheric pressure, while also addressing pollution control and resource recovery. The traditional Haber-Bosch process for ammonia synthesis has high energy consumption and large emissions, so it is of great significance to develop green and low-energy NO3RR technology. However, NO3RR reaction involves multi-electron transfer and proton coupling, with complex pathways and many intermediate products, and is also easily affected by the competition of hydrogen evolution reaction (HER), which reduces the faradic efficiency and selectivity of ammonia. The performance of the catalyst is highly dependent on the supply and utilization efficiency of active hydrogen (H ), and an ideal catalyst needs to balance hydrogen generation and consumption to promote nitrate hydrogenation and inhibit hydrogen evolution. Among existing catalysts, indium oxide (In2O3) can better adsorb and activate nitrate, but its hydrogen activation ability is weak, which limits the hydrogenation step and makes the ammonia selectivity unsatisfactory. Pd-based materials have strong water dissociation and hydrogen adsorption ability and can provide sufficient H , but they are prone to HER, causing electron waste and efficiency loss. Therefore, it is difficult to use In2O3 or Pd alone to balance the activation and hydrogenation processes of nitrate, so it is necessary to design and regulate the structure of the material to construct dual-functional active sites to achieve synergistic promotion of the two processes. SUMMARY
[0004] The purpose of the present application is to provide a Pd cluster modified In2O3 composite material, a preparation method and application thereof. Through material design and structure regulation, the prepared Pd@In2O3 has dual-functional active sites, which can synergistically promote the activation and hydrogenation processes of nitrate in electrocatalytic nitrate reduction reaction, exhibit excellent catalytic activity and stability in electrocatalytic nitrate reduction to synthesize ammonia, and have good application prospects.
[0005] To achieve the above purpose, the present application provides a preparation method of a Pd cluster modified In2O3 composite material, comprising the following steps: S1, dissolve indium salt and terephthalic acid in an organic solvent, stir, and then perform hydrothermal reaction, centrifuge, wash and dry after the reaction is completed to obtain a metal organic framework material; S2. The metal-organic framework material obtained in S1 is heat-treated, then dispersed in water, and then filtered and dried to obtain a solid, denoted as In2O3. S3. Disperse the In2O3 obtained in S2 in water, add a stabilizer and sonicate, then add palladium salt solution and stir, then inject reducing agent solution to react. After the reaction is completed, centrifuge, wash and dry to obtain b-Pd@In2O3. S4. The b-Pd@In2O3 obtained in S3 is heat-treated and then dispersed in water; after filtration and drying, a composite material of Pd cluster modified In2O3 is obtained, denoted as Pd@In2O3.
[0006] Preferably, in S1, the indium salt includes indium nitrate, and the organic solvent includes N,N-dimethylformamide.
[0007] Preferably, in S1, the mass ratio of indium salt to terephthalic acid is 1:1-5, the mass-volume ratio of indium salt to organic solvent is 1g:20-50mL, the stirring time is 15-30min, the hydrothermal reaction temperature is 80-120℃, and the hydrothermal reaction time is 18-24h.
[0008] Preferably, in S2, the heat treatment is carried out in an air atmosphere. The heat treatment process is as follows: first, the temperature is raised to 100-150℃ at a rate of 2-5℃ / min and held for 1-3 hours, and then the temperature is raised to 400-500℃ at a rate of 2-5℃ / min and held for 1-3 hours.
[0009] Preferably, in S3, the stabilizer includes polyvinylpyrrolidone, the palladium salt includes sodium chloropalladium, and the reducing agent includes sodium borohydride.
[0010] Preferably, in S3, the mass-to-volume ratio of water to In2O3 is 0.2-0.3 mL:1 mg, the mass ratio of stabilizer to In2O3 is 0.05-0.1:1, the concentration of palladium salt solution is 50-200 mM, the amount of palladium salt added is such that the theoretical loading of Pd in the final composite material is 0.5-5 wt%, the concentration of reducing agent solution is 0.05-0.1 M, the volume ratio of reducing agent to water is 1-2:20, the reaction time is 2-3 h, and the reaction temperature is 18-25 °C.
[0011] Preferably, in S4, the heat treatment is carried out in an air atmosphere. The heat treatment process is as follows: first, the temperature is raised to 100-150℃ at a rate of 2-5℃ / min and held for 1-3 hours, and then the temperature is raised to 400-500℃ at a rate of 2-5℃ / min and held for 1-3 hours.
[0012] The present invention also provides a composite material of Pd cluster modified In2O3, which is prepared by the above-described method for preparing a composite material of Pd cluster modified In2O3.
[0013] The present invention also provides an application of a Pd cluster-modified In2O3 composite material, which is used as a cathode for electrocatalytic nitrate reduction reaction to synthesize ammonia.
[0014] Therefore, the present invention, employing the above-mentioned Pd cluster-modified In2O3 composite material, its preparation method, and its application, has the following beneficial effects: 1. This invention prepares Pd cluster-modified indium oxide (In2O3) composite materials through a simple in-situ reduction-heat treatment method. This method is not only simple and quick to operate and easy to mass-produce, but also, during the preparation process, polyvinylpyrrolidone (PVP) acts as a stabilizer to effectively inhibit the excessive aggregation of palladium species and ensure that they are uniformly dispersed in the form of sub-nanometer clusters. Sodium borohydride (NaBH4) acts as a strong reducing agent to rapidly reduce palladium ions, and the subsequent heat treatment process optimizes the electronic interaction between the cluster structure and the support.
[0015] 2. In the preparation of Pd cluster-modified indium oxide composite material in this invention, Pd clusters were selected and loaded onto a specific In2O3 support, thereby ensuring that the resulting composite material has excellent catalytic activity and stability.
[0016] 3. The Pd cluster-modified indium oxide composite material prepared by this invention has advantages such as bifunctional active sites and large specific surface area. It exhibits excellent catalytic activity and stability in the electrocatalytic reduction of nitrate to ammonia and has good application prospects.
[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0018] Figure 1 X-ray diffraction (XRD) patterns of Pd@In2O3 prepared in Example 1 and In2O3 prepared in Comparative Example 1 of the present invention; Figure 2 Scanning electron microscope (SEM) images of Pd@In2O3 prepared in Example 1 and In2O3 prepared in Comparative Example 1 of the present invention; Figure 3 Transmission electron microscope (HAADF-STEM) images of Pd@In2O3 prepared in Example 1 and In2O3 prepared in Comparative Example 1 of the present invention. Figure 4This is a comparison chart showing the ammonia yield of electrocatalytic nitrate reduction reactions in Application Example 1 and Application Example 2 of the present invention in 0.5M Na2SO4 and 0.1M KNO3 electrolytes; Figure 5 This is a comparison chart of the Faradaic efficiency (FE) of application examples 1 and 2 of the present invention in the electrocatalytic reduction of nitrate in 0.5M Na2SO4 and 0.1M KNO3 electrolytes; Figure 6 The graph shows the cyclic performance of Application Example 1 of the present invention after 10 cycles at a voltage of -0.5V. Figure 7 The images shown are scanning electron microscope (SEM) and transmission electron microscope (HAADF-STEM) images of Example 1 of the present invention after 10 cycles in 0.5M Na2SO4 and 0.1M KNO3 electrolytes. Figure 8 The X-ray diffraction pattern (XRD) of Example 1 of this invention after 10 cycles in 0.5M Na2SO4 and 0.1M KNO3 electrolytes. Detailed Implementation
[0019] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.
[0020] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.
[0021] In this invention, unless otherwise specified, the test materials and instruments are all conventional test materials in the field and can be purchased through commercial channels.
[0022] Example 1 This invention provides a method for preparing a composite material of In2O3 modified with Pd clusters, comprising the following steps: S1. Dissolve 1g of indium nitrate and 2g of terephthalic acid in 30mL of N,N-dimethylformamide. After stirring for 20min, transfer the solution to a 50mL reactor and carry out a hydrothermal reaction at 100℃ for 24h. After the reaction is completed, centrifuge, wash with ethanol and water, and dry under vacuum at 60℃ to obtain a solid metal-organic framework material, denoted as MIL-68(In). S2. The MIL-68(In) obtained in S1 was calcined in air under programmed temperature rise. First, the temperature was raised to 150°C at a rate of 5°C / min and held for 2 hours. Then, the temperature was raised to 500°C at the same rate and held for 2 hours. Then, it was dispersed in deionized water to remove residual salts. After filtration and vacuum drying at 60°C, a solid was obtained, which was denoted as In2O3. S3. Disperse 100 mg In2O3 obtained in S2 in 20 mL of deionized water, add 8 mg of polyvinylpyrrolidone and sonicate, then add 200 μL of sodium chloropalladium (Na2PdCl4) solution (100 mM), stir at room temperature for 1 h, and then slowly inject 2 mL of sodium borohydride (NaBH4) solution (50 mM) to react. After reacting for 2 h, centrifuge, wash with ethanol and deionized water, and dry under vacuum at 60 °C for 12 h to obtain b-Pd@In2O3; S3. The b-Pd@In2O3 obtained in S3 was calcined in air under programmed temperature rise. First, the temperature was raised to 150℃ at a rate of 5℃ / min and held for 2 hours. Then, the temperature was raised to 500℃ at the same rate and held for 2 hours. Then, it was dispersed in deionized water to remove residual salts. After filtration and vacuum drying at 60℃, a solid was obtained, which was denoted as Pd@In2O3.
[0023] Comparative Example 1 The preparation method of In2O3 includes the following steps: Step 1: Dissolve 1g of indium nitrate and 2g of terephthalic acid in 30mL of N,N-dimethylformamide, stir for 20min, transfer to a 50mL reaction vessel, and carry out hydrothermal reaction at 100℃ for 24h. After the reaction is completed, centrifuge, wash with ethanol and water, and dry under vacuum at 60℃ to obtain a solid metal-organic framework material, denoted as MIL-68(In). Step 2: The MIL-68(In) obtained in Step 1 is subjected to programmed temperature calcination in air atmosphere. First, the temperature is increased to 150℃ at a rate of 5℃ / min and held for 2 hours. Then, the temperature is increased to 500℃ at the same rate and held for 2 hours. Then, it is dispersed in deionized water to remove residual salts. After filtration, it is dried under vacuum at 60℃ to obtain a solid, which is denoted as In2O3.
[0024] Application Example 1 5 mg of Pd@In2O3 prepared in Example 1 was dispersed in a mixture of 1 mL isopropanol and 20 μL of 5 wt% Nafion solution, and sonicated for 2 h to form a uniform catalyst ink. 100 μL of this catalyst ink was uniformly drop-coated onto 1 cm × 1 cm carbon paper (CP), dried at room temperature, and used as the cathode of the working electrode, with a catalyst loading of 0.5 mg·cm⁻¹. -2 Using a Pt sheet as the counter electrode and Ag / AgCl (saturated KCl) as the reference electrode, the electrochemical reaction was carried out in an H-type electrolytic cell (separated by a Nafion 117 proton exchange membrane) in 0.5M Na2SO4 and 0.1M KNO3 electrolyte (pH≈6.8).
[0025] Application Example 2 This application example is operated in the same way as application example 1, except that 5 mg of In2O3 prepared in comparative example 1 is dispersed in the mixed solution.
[0026] The Pd@In2O3 prepared in Example 1 and the In2O3 prepared in Comparative Example 1 were characterized by X-ray diffraction, and the results are as follows: Figure 1 As shown, from Figure 1 As can be seen, the diffraction peaks of In2O3 and Pd@In2O3 correspond perfectly to the In2O standard card (PDF#06-0416).
[0027] The Pd@In2O3 prepared in Example 1 and the In2O3 prepared in Comparative Example 1 were characterized by scanning electron microscopy, and the results are as follows: Figure 2 As shown, where Figure 2 (a) is a scanning electron microscope (SEM) image of In₂O₃, and (b) is a scanning electron microscope (SEM) image of Pd@In₂O₃. Figure 2 It can be seen that In2O3 and Pd@In2O3 have hollow rod-like structures.
[0028] The Pd@In2O3 prepared in Example 1 and the In2O3 prepared in Comparative Example 1 were characterized by transmission electron microscopy, and the results are as follows: Figure 3 As shown, where Figure 3 (a) is a transmission electron microscope (TEM) image of In₂O₃, (b) is a TEM image of Pd@In₂O₃, and (c) is a spherical aberration electron diffraction pattern of Pd@In₂O₃. Figure 3 It can be seen that Pd is distributed in clusters.
[0029] The electrochemical reactions of Application Examples 1 and 2 were subjected to constant potential electrolysis for 1 hour in 50 mL of 0.5 M Na2SO4 and 0.1 M KNO3 electrolytes at different potentials. All potentials were converted to the potential relative to the reversible hydrogen electrode (RHE) according to Equation (1). The electrolyte in the cathode chamber was filtered through a 0.45 μm polytetrafluoroethylene (PTEF) membrane filter to obtain the reaction filtrate. The concentration of ammonia in the product was detected by ultraviolet spectrophotometer. 2 mL of the diluted electrolyte after the electrochemical reaction was mixed with 2 mL of 1.0 M NaOH solution, which contained 5 wt% salicylic acid and 5 wt% sodium citrate. Then, 1 mL of 0.05 M NaClO solution and 0.2 mL (1 wt.%) sodium nitroferricyanide solution were added, and the mixture was thoroughly mixed to ensure homogeneity. The reaction was carried out in the dark for 2 hours. Subsequently, the absorbance of the solution at a wavelength of 662 nm after the reaction was detected by ultraviolet spectrophotometer, and the concentration of NH4 in the electrolyte was calculated. + The yield and Faraday efficiency (FE) results are as follows Figure 4 and Figure 5 As shown, whereFigure 4 For ammonia production, Figure 5 For Faraday efficiency. From Figure 4 As can be seen, within the potential range of -0.3 to -0.7 V vs. RHE, the ammonia yield in the electrocatalytic reduction of nitrate to ammonia synthesis using Pd@In2O3 as the cathode material increases with the application of a higher negative potential. Figure 5 As can be seen, Pd@In2O3 exhibits the best performance at a voltage of -0.5V vs. RHE, with an FE of 95.26% and an ammonia yield of 442.76 μmol·h⁻¹. -1 ·cm -2 However, due to the competitive release of hydrogen, the FE of In2O3 is significantly reduced, indicating that Pd@In2O3 performs better than In2O3.
[0030] E(vs.RHE)=E(vs.Ag / AgCl)+0.197V+0.059×pH (1).
[0031] Stability is another important indicator for evaluating the practical application of electrocatalysts. Application Example 1 underwent 10 cycle tests at a voltage of -0.5V, and the results are as follows: Figure 6 As shown, from Figure 6 As can be seen, the ammonia yield and Faradaic efficiency of Pd@In2O3 as the cathode material remained almost unchanged in the electrocatalytic reduction of nitrate to ammonia, proving that the Pd cluster-modified indium oxide composite material Pd@In2O3 prepared in Example 1 has excellent stability. Subsequently, the electrolyzed samples were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, and the results are as follows: Figure 7 and Figure 8 As shown, where Figure 7 In the image, (a) is a scanning electron microscope image of Pd@In2O3 after the reaction, and (b) is a transmission electron microscope image of Pd@In2O3 after the reaction. Figure 8 The X-ray diffraction pattern of Pd@In2O3 after reaction is shown below. Figure 7 and Figure 8 It can be seen that, with Figures 1-3 In contrast, the morphology and crystal phase of Pd@In2O3 remained unchanged, further demonstrating the excellent stability of Pd@In2O3 material.
[0032] Therefore, this invention employs the aforementioned Pd cluster-modified In2O3 composite material, its preparation method, and its application. Through material design and structural regulation, the prepared Pd@In2O3 possesses bifunctional active sites, achieving synergistic promotion of nitrate activation and hydrogenation processes in the electrocatalytic nitrate reduction reaction. It exhibits excellent catalytic activity and stability in the electrocatalytic nitrate reduction to ammonia synthesis and has promising application prospects.
[0033] 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 them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A method for preparing a composite material of In2O3 modified with Pd clusters, characterized in that: Includes the following steps: S1. Dissolve indium salt and terephthalic acid in an organic solvent, stir and carry out a hydrothermal reaction. After the reaction is completed, centrifuge, wash and dry to obtain metal-organic framework material. S2. The metal-organic framework material obtained in S1 is heat-treated, then dispersed in water, and then filtered and dried to obtain a solid, denoted as In2O3. S3. Disperse the In2O3 obtained in S2 in water, add a stabilizer and sonicate, then add palladium salt solution and stir, then inject reducing agent solution to react. After the reaction is completed, centrifuge, wash and dry to obtain b-Pd@In2O3. S4. The b-Pd@In2O3 obtained in S3 is heat-treated and then dispersed in water; after filtration and drying, a composite material of Pd cluster modified In2O3 is obtained, denoted as Pd@In2O3.
2. The method for preparing a Pd cluster-modified In2O3 composite material according to claim 1, characterized in that: In S1, the indium salt includes indium nitrate, and the organic solvent includes N,N-dimethylformamide.
3. The method for preparing a composite material of Pd cluster modified In2O3 according to claim 1, characterized in that: In S1, the mass ratio of indium salt to terephthalic acid is 1:1-5, the mass-volume ratio of indium salt to organic solvent is 1g:20-50mL, the stirring time is 15-30min, the hydrothermal reaction temperature is 80-120℃, and the hydrothermal reaction time is 18-24h.
4. The method for preparing a composite material of Pd cluster modified In2O3 according to claim 1, characterized in that: In S2, the heat treatment is carried out in an air atmosphere. The heat treatment process is as follows: first, the temperature is raised to 100-150℃ at a rate of 2-5℃ / min and held for 1-3 hours, and then the temperature is raised to 400-500℃ at a rate of 2-5℃ / min and held for 1-3 hours.
5. The method for preparing a composite material of Pd cluster modified In2O3 according to claim 1, characterized in that: In S3, the stabilizer includes polyvinylpyrrolidone, the palladium salt includes sodium chloropalladium, and the reducing agent includes sodium borohydride.
6. The method for preparing a composite material of Pd cluster modified In2O3 according to claim 1, characterized in that: In S3, the mass-to-volume ratio of water to In2O3 is 0.2-0.3 mL:1 mg, the mass ratio of stabilizer to In2O3 is 0.05-0.1:1, the concentration of palladium salt solution is 50-200 mM, the amount of palladium salt added is such that the theoretical Pd loading in the final composite material is 0.5-5 wt%, the concentration of reducing agent solution is 0.05-0.1 M, the volume ratio of reducing agent to water is 1-2:20, the reaction time is 2-3 h, and the reaction temperature is 18-25 °C.
7. The method for preparing a composite material of Pd cluster modified In2O3 according to claim 1, characterized in that: In S4, the heat treatment is carried out in an air atmosphere. The heat treatment process is as follows: first, the temperature is raised to 100-150℃ at a rate of 2-5℃ / min and held for 1-3 hours, and then the temperature is raised to 400-500℃ at a rate of 2-5℃ / min and held for 1-3 hours.
8. A composite material of In2O3 modified with Pd clusters, characterized in that: The composite material of Pd cluster modified In2O3 was prepared using the method described in any one of claims 1-7.
9. An application of a composite material with Pd clusters modified In2O3, characterized in that: The Pd cluster-modified In2O3 composite material of claim 8 is used as a cathode for the electrocatalytic reduction reaction of nitrate to synthesize ammonia.