A cu pd binary alloy electrocatalyst supported on kish graphite and a preparation method and application thereof

Abstract

The application provides a kind of electrocatalyst of CuPd binary alloy supported on Vulcan carbon and its preparation method and application, and relates to the technical field of electrocatalyst.The CuPd alloy structure is synthesized by one-step solvothermal method, the synergistic catalytic effect of Pd and Cu is realized, the crystal form is controlled by introducing halide, and the CuPd nanocrystal clusters are supported on the surface of Vulcan carbon by ultrasonic technology, so that the high-activity and high-stability electrocatalytic material is obtained, which not only enhances the adsorption and activation of NO3 ‑ , but also improves the supply capacity of H, thereby significantly improving the generation efficiency and selectivity of NH3.The preparation method of the application is simple, controllable in cost, low in energy consumption, mild in conditions, and good in product morphology;The electrocatalyst of CuPd binary alloy supported on Vulcan carbon obtained by the application has good catalytic activity and stability under alkaline conditions, realizes a Faraday efficiency of more than 85%, and the current is stable for more than 10 hours in I-T test under neutral conditions.

Description

Technical Field

[0001] This invention relates to the field of electrocatalyst technology, and in particular to a Ketjen carbon-supported CuPd binary alloy electrocatalyst, its preparation method, and its application. Background Technology

[0002] Nitrate (NO3) - NO3, as a nitrogen-containing pollutant, is widely present in agricultural and industrial wastewater, causing not only eutrophication but also posing a threat to human health. Therefore, utilizing NO3... - Resource utilization of waste not only achieves waste treatment but also enables the green synthesis of NH3, offering dual environmental and economic benefits. Therefore, finding an environmentally friendly and energy-efficient NH3 synthesis technology has become a current research focus, and high-performance electrocatalysts are the core support for the success of this technology.

[0003] In the preparation of electrocatalysts, Cu-based catalysts exhibit excellent adsorption and activation effects, but Cu's adsorption of *H is too weak. Pd-based materials possess excellent hydrogenation activity, but suffer from severe agglomeration and numerous byproducts. Alloying is an effective means to improve their performance; however, existing CuPd alloy catalysts still face many problems: 1. Preparation often employs a two-step method, requiring the addition of strong reducing agents, resulting in complex processes and high costs; 2. There is a lack of efficient crystal form control methods, leading to uneven particle size and prominent agglomeration problems; 3. The binding force between the active component and the support is weak, making it prone to detachment and deactivation during the reaction. Furthermore, existing CuPd-based catalysts exhibit insufficient stability under alkaline conditions, with most having a cycle life of less than 5 hours and a Faraday efficiency that struggles to exceed 80%, failing to meet practical requirements.

[0004] Furthermore, the support has a crucial impact on catalyst performance, requiring a combination of high specific surface area, excellent conductivity, and strong stability. Traditional carbon-based supports (such as carbon nanotubes and reduced graphene oxide) suffer from problems such as high cost, poor dispersion, or unreasonable pore structure. Although Ketjen carbon possesses advantages such as large specific surface area and excellent conductivity, there are currently no reports on its efficient combination with CuPd-based catalysts as nitrate reduction catalysts. Summary of the Invention

[0005] Therefore, this invention proposes a CuPd binary alloy electrocatalyst supported on Ketjen carbon, its preparation method, and its application.

[0006] The technical solution of this invention is implemented as follows: A CuPd binary alloy electrocatalyst supported on Kettich carbon, wherein the electrocatalyst is CuPd binary alloy nanoparticles supported on the surface of Kettich carbon, and the molar ratio of Cu to Pd is 1:0.5-2.

[0007] A method for preparing a Ketjen carbon-supported CuPd binary alloy electrocatalyst, comprising the following steps: (1) Mix copper salt, palladium salt, halide, long-chain alkylamine solvent and polyol dispersant, sonicate, carry out heating alloying reaction, centrifuge, wash, and obtain CuPd alloy nanoparticles. (2) CuPd alloy nanoparticles were added to n-hexane, Ketjen carbon was added, ultrasonic treatment was performed, centrifuged, washed and dried to obtain Ketjen carbon-supported CuPd binary alloy electrocatalyst.

[0008] Furthermore, in step (1), the mass ratio of the copper salt, palladium salt and halide is 10-20:5-10:10-20.

[0009] Furthermore, the copper salt is any one of copper acetylacetonate, copper chloride, and copper nitrate; The palladium salt is any one of sodium tetrachloropalladium, palladium chloride, and palladium nitrate. The halide is any one of potassium bromide, potassium chloride, and potassium iodide.

[0010] Furthermore, in step (1), the volume ratio of the long-chain alkylamine solvent to the polyol dispersant is 1-3:0.1-0.5; The liquid-to-solid ratio of the long-chain alkylamine solvent to the halide is 1-3:10-20 mL / mg.

[0011] Furthermore, the long-chain alkylamine solvent is oleylamine; the polyol dispersant is ethylene glycol.

[0012] Furthermore, in step (1), the ultrasonic treatment is performed at 35-40KHz and 450-500W for 1-2 hours; The heating alloying reaction is carried out at a temperature of 140-160℃, a rotation speed of 300-600 rpm, and a time of 2-3 hours.

[0013] Furthermore, in step (2), the solid-liquid ratio of the CuPd alloy nanoparticles to n-hexane is 2-5:3-7 mg / mL; The mass ratio of the Ketsin carbon to the CuPd alloy nanoparticles is 10-20:2-5; The ultrasonic treatment is performed at 35-40KHz and 450-500W for 1-2 hours.

[0014] Application of the Ketjen carbon-supported CuPd binary alloy electrocatalyst prepared by any of the above methods in electrocatalytic reactions.

[0015] Furthermore, the electrocatalytic reaction is a potassium nitrate electrocatalytic reduction reaction, with 0.1M KOH + 0.1M KNO3 as the electrolyte and the Ketjen carbon-supported CuPd binary alloy electrocatalyst as the catalyst.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves a synergistic catalytic effect between Pd and Cu through a one-step solvothermal synthesis of CuPd alloy structures. Halides are introduced to regulate the crystal structure, and ultrasonic technology is used to immobilize CuPd nanocrystal clusters on the surface of Ketjen carbon, resulting in a highly active and stable electrocatalytic material that enhances the catalytic activity against NO3-. - The adsorption and activation further enhance the supply capacity of *H, thereby significantly improving the generation efficiency and selectivity of NH3.

[0017] The preparation method of this invention is simple, cost-controllable, energy-efficient, and mild, and produces a product with good morphology. The obtained Ketjen carbon-supported CuPd binary alloy electrocatalyst exhibits good catalytic activity and stability under alkaline conditions, achieving a Faraday efficiency of more than 85%, and the current remains stable for more than 10 hours under neutral conditions during IT testing. Attached Figure Description

[0018] Figure 1 This is a transmission electron microscope (TEM) image of the Ketjen carbon-supported CuPd binary alloy electrocatalyst from Example 1.

[0019] Figure 2 The image shows the X-ray diffraction pattern of the Ketjen carbon-supported CuPd binary alloy electrocatalyst of Example 1.

[0020] Figure 3 The image shows the X-ray diffraction pattern of the electrocatalyst material prepared in Example 2.

[0021] Figure 4 The image shows the X-ray diffraction pattern of the electrocatalyst material prepared in Example 3.

[0022] Figure 5 The image shows the X-ray diffraction pattern of the electrocatalyst material prepared in Example 4.

[0023] Figure 6 The image shows the X-ray diffraction pattern of the electrocatalyst material prepared in Comparative Example 1.

[0024] Figure 7 The image shows the X-ray diffraction pattern of the electrocatalyst material prepared in Comparative Example 2.

[0025] Figure 8 The image shows the X-ray diffraction pattern of the electrocatalyst material prepared in Comparative Example 3.

[0026] Figure 9 Transmission electron microscopy (TEM) image of the electrocatalyst material prepared in Comparative Example 4.

[0027] Figure 10 Transmission electron microscopy (TEM) image of the electrocatalyst material prepared in Comparative Example 5.

[0028] Figure 11The graph shows the electrocatalytic ammonia production performance of the electrocatalyst material in Example 1.

[0029] Figure 12 The graph shows the electrocatalytic ammonia production performance of the electrocatalyst material in Comparative Example 4.

[0030] Figure 13 The graph shows the electrocatalytic ammonia production performance of the electrocatalyst material in Comparative Example 5.

[0031] Figure 14 This is a graph showing the long-term stability of the electrocatalyst material in Example 1. Detailed Implementation

[0032] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention.

[0033] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0034] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0035] The Ketjen carbon of this invention is Ketjen carbon EC-300J.

[0036] Example 1 A method for preparing a Ketjen carbon-supported CuPd binary alloy electrocatalyst, comprising the following steps: (1) 6.3 mg copper acetylacetonate, 14.1 mg sodium tetrachloropalladium, 20 mg potassium bromide, 3 mL oleylamine and 0.5 mL ethylene glycol were added to a 25 mL reaction flask and mixed. The mixture was treated at 40 kHz and 500 W for 1 h. The reaction flask was placed in an oil bath and reacted at 160 °C and 450 pm for 2 h. After centrifugation, the solid product was washed with a mixed solvent (1:1 volume ratio of anhydrous ethanol and acetone) and dried to obtain CuPd alloy nanoparticles. (2) 4 mg of CuPd alloy nanoparticles were added to 6 mL of n-hexane, and 20 mg of Ketjen carbon was added. The mixture was ultrasonically treated at 40 kHz and 500 W for 1 h, centrifuged, washed, and vacuum dried to obtain a Ketjen carbon-supported CuPd binary alloy electrocatalyst. The molar ratio of Cu to Pd in ​​the electrocatalyst was 0.9:1.

[0037] result: The Ketjen carbon-supported CuPd binary alloy electrocatalyst prepared in Example 1 was subjected to transmission electron microscopy (TEM) to observe its morphology. (See [reference needed]). Figure 1 The transmission electron microscope (TEM) image shows that the CuPd binary alloy electrocatalyst supported on Ketjen carbon has a nanoparticle structure, with CuPd alloy particles uniformly loaded on the surface of Ketjen carbon.

[0038] The Ketjen carbon-supported CuPd binary alloy electrocatalyst prepared in Example 1 was subjected to X-ray diffraction analysis. (See [link to relevant documentation]). Figure 2 The X-ray diffraction pattern shows that the diffraction peaks of the CuPd alloy are between those of single metals Pd and Cu, and are completely consistent with the X-ray diffraction fitting structure of the CuPd alloy.

[0039] Example 2 Based on Example 1, NiPd@Ketjen carbon binary alloy catalysts with different proportions were prepared by changing the type of metal salt precursor and the ratio.

[0040] The specific steps include: (1) Nickel chloride (4.61 mg, 0.0356 mmol), sodium tetrachloropalladium (10.46 mg, 0.0356 mmol), 20 mg potassium bromide, 3 mL oleylamine and 0.5 mL ethylene glycol were added sequentially to a 25 mL reaction flask and mixed. The mixture was treated at 40 kHz and 500 W for 1 h. The reaction flask was then placed in an oil bath and reacted at 160 °C and 450 pm for 2 h. After centrifugation, the solid product was washed with a mixed solvent (1:1 volume ratio of anhydrous ethanol and acetone) and dried to obtain NiPd alloy nanoparticles. (2) Add 4 mg of NiPd alloy nanoparticles to 6 mL of n-hexane, add 20 mg of Ketjen carbon, sonicate at 40 kHz and 500 W for 1 h, centrifuge, wash, and vacuum dry to obtain Ketjen carbon-supported NiPd binary alloy electrocatalyst.

[0041] In step (1), the total molar amount of Ni and Pd is kept constant at 0.0712 mmol, and the molar ratio of Ni and Pd is changed to 3:1, 2:1, 1:2, and 1:3 respectively.

[0042] Example 3 Based on Example 1, InPd@Ketjen carbon binary alloy catalysts with different ratios were prepared by changing the type of metal salt precursor and the ratio.

[0043] The specific steps include: (1) Indium chloride (5.34 mg, 0.0356 mmol), sodium tetrachloropalladium (10.46 mg, 0.0356 mmol), 20 mg potassium bromide, 3 mL oleylamine and 0.5 mL ethylene glycol were added to a 25 mL reaction flask and mixed. The mixture was treated at 40 kHz and 500 W for 1 h. The reaction flask was then placed in an oil bath and reacted at 160 °C and 450 pm for 2 h. After centrifugation, the solid product was washed with a mixed solvent (1:1 volume ratio of anhydrous ethanol and acetone) and dried to obtain InPd alloy nanoparticles. (2) Add 4 mg of InPd alloy nanoparticles to 6 mL of n-hexane, add 20 mg of Ketjen carbon, sonicate at 40 kHz and 500 W for 1 h, centrifuge, wash, and vacuum dry to obtain Ketjen carbon-supported InPd binary alloy electrocatalyst.

[0044] In step (1), the total molar amount of In and Pd is kept constant at 0.0712 mmol, and the molar ratio of In and Pd is changed to 3:1, 2:1, 1:2, and 1:3 respectively.

[0045] Example 4 Based on Example 1, InCu@Ketjen carbon binary alloy catalysts with different ratios were prepared by changing the type of metal salt precursor and the ratio.

[0046] The specific steps include: (1) Indium chloride (5.34 mg, 0.0356 mmol), copper chloride (9.3 mg, 0.0356 mmol), 20 mg potassium bromide, 3 mL oleylamine and 0.5 mL ethylene glycol were added to a 25 mL reaction flask and mixed. The mixture was treated at 40 kHz and 500 W for 1 h. The reaction flask was placed in an oil bath and reacted at 160 °C and 450 pm for 2 h. After centrifugation, the solid product was washed with a mixed solvent (1:1 volume ratio of anhydrous ethanol and acetone) and dried to obtain InCu alloy nanoparticles. (2) Add 4 mg of InCu alloy nanoparticles to 6 mL of n-hexane, add 20 mg of Ketjen carbon, sonicate at 40 kHz and 500 W for 1 h, centrifuge, wash, and vacuum dry to obtain Ketjen carbon-supported InCu binary alloy electrocatalyst.

[0047] In step (1), the total molar amount of In and Cu is kept constant at 0.0712 mmol, and the molar ratio of In and Cu is changed to 3:1, 2:1, 1:2, and 1:3 respectively.

[0048] result: X-ray diffraction tests were performed on the various binary alloy electrocatalyst materials prepared in Examples 2-4. (See attached diagram.) Figure 3-5 The X-ray diffraction patterns show that the diffraction peaks of NiPd in ​​Example 2, PdIn in Example 3, and CuIn in Example 4 are consistent with the single metal diffraction peaks and have not shifted. In fact, some metals have not been reduced, indicating that the alloyed structure was not formed in Examples 2-4, which is completely different from Example 1.

[0049] Comparative Example 1 The difference from Example 1 is that the potassium bromide in step (1) is replaced with potassium iodide and potassium chloride respectively, while the rest is the same as in Example 1.

[0050] Comparative Example 2 The difference from Example 1 is that the oleylamine in step (1) is replaced with hexadecylamine and heptadecanylamine respectively, while the rest is the same as in Example 1.

[0051] Comparative Example 3 The difference from Example 1 is that the ethylene glycol in step (1) is replaced with neopentyl glycol and 1,4-butanediol, respectively, while the rest is the same as in Example 1.

[0052] result: X-ray diffraction tests were performed on the materials prepared in proportions 1-3. (See attached text.) Figure 6-8 The X-ray diffraction patterns show that in Comparative Example 1, replacing potassium bromide with potassium iodide or potassium chloride resulted in the formation of a CuPd alloy structure, but the diffraction peak intensity was significantly reduced, indicating poor crystallization. In Comparative Example 2, replacing oleylamine with hexadecylamine or heptadecylamine failed to form an alloy structure, and the metal was not even reduced. In Comparative Example 3, replacing ethylene glycol with neopentyl glycol or 1,4-butanediol resulted in the formation of an alloy structure, but the diffraction peaks of single-metal impurities were clearly visible, indicating incomplete reduction and structural instability.

[0053] The X-ray diffraction results of Examples 1-4 and Comparative Examples 1-3 show that the optimal experimental conditions for the solvothermal alloying preparation of the Ketjen carbon-supported CuPd binary alloy electrocatalyst of the present invention are Cu and Pd as the metal source and oleylamine, potassium bromide and ethylene glycol as the reactant conditions.

[0054] Comparative Example 4 The difference from Example 1 is that step (1) lacks copper acetylacetone and only contains 21.1 mg of sodium tetrachloropalladium, which is used to prepare the Ketjen carbon-supported Pd catalyst. The rest is the same as in Example 1.

[0055] Comparative Example 5 The difference from Example 1 is that sodium tetrachloropalladium is missing in step (1), and only 18.9 mg of copper acetylacetone is used to prepare the Ketjen carbon-supported Cu catalyst. The rest is the same as in Example 1.

[0056] result: The materials prepared in Comparative Examples 4-5 were subjected to transmission electron microscopy (TEM) to observe their morphology. (See [reference needed]). Figure 9-10 The transmission electron microscopy (TEM) images show that the Pd catalyst in Comparative Example 4 and the Cu catalyst in Comparative Example 5 both exist as aggregated nanoparticles, non-uniformly loaded on the surface of Ketjen carbon.

[0057] Test case The catalyst materials obtained in Example 1 and Comparative Examples 4-5 were tested for nitrate catalytic activity.

[0058] Experimental Methods: A three-electrode system was used for testing. Carbon paper was clamped between electrode clips as the working electrode, a silver / silver chloride electrode as the reference electrode, and a platinum sheet as the counter electrode. A mixed electrolyte solution of 0.1 M KNO3 + 0.1 M KOH was used, and the reducing activity was measured under Ar gas purging. The applied voltage range was 0.3 volts (reversible hydrogen electrode) to -0.4 volts (reversible hydrogen electrode), and the test duration was 1 hour. The ammonia production performance of the materials prepared in Example 1 and Comparative Examples 4-5 under constant pressure was tested.

[0059] The results are as follows Figure 11-13 It can be seen that the optimal reaction voltage in Example 1 is 0 volts (reversible hydrogen electrode), and when the voltage is 0 volts (reversible hydrogen electrode), the Faraday efficiency of the catalyst material in Example 1 is greater than 85%, which is much greater than the Faraday efficiency of the single metal catalysts in Comparative Examples 4-5.

[0060] The ammonia production performance in the constant potential experiment with the optimal voltage of 0 volts (reversible hydrogen electrode) is shown in Table 1.

[0061] Table 1

[0062] Its stability was tested by performing an IT test at a voltage of -1.2 volts (reversible hydrogen electrode) and in a neutral solution for 10 h.

[0063] The results are as follows Figure 14 As can be seen, the catalyst material of Example 1 of this invention maintained a stable current for more than 10 hours during long-term IT testing. The Ketjen carbon-supported CuPd binary alloy catalyst prepared by this invention exhibits excellent electrocatalytic performance, high efficiency, and good stability.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A CuPd binary alloy electrocatalyst supported on Ketjen carbon, characterized in that, The electrocatalyst is CuPd binary alloy nanoparticles supported on the surface of Ketjen carbon, with a Cu to Pd molar ratio of 1:0.5-2.

2. The method for preparing a Ketjen carbon-supported CuPd binary alloy electrocatalyst according to claim 1, characterized in that, The specific steps include: (1) Mix copper salt, palladium salt, halide, long-chain alkylamine solvent and polyol dispersant, sonicate, carry out heating alloying reaction, centrifuge, wash, and obtain CuPd alloy nanoparticles. (2) CuPd alloy nanoparticles were added to n-hexane, Ketjen carbon was added, ultrasonic treatment was performed, centrifuged, washed and dried to obtain Ketjen carbon-supported CuPd binary alloy electrocatalyst.

3. The method for preparing a Ketjen carbon-supported CuPd binary alloy electrocatalyst as described in claim 2, characterized in that, In step (1), the mass ratio of the copper salt, palladium salt and halide is 10-20:5-10:10-20.

4. The method for preparing a Ketjen carbon-supported CuPd binary alloy electrocatalyst as described in claim 3, characterized in that, The copper salt is any one of copper acetylacetonate, copper chloride, and copper nitrate. The palladium salt is any one of sodium tetrachloropalladium, palladium chloride, and palladium nitrate. The halide is any one of potassium bromide, potassium chloride, and potassium iodide.

5. The method for preparing a Ketjen carbon-supported CuPd binary alloy electrocatalyst as described in claim 2, characterized in that, In step (1), the volume ratio of the long-chain alkylamine solvent to the polyol dispersant is 1-3:0.1-0.5; The liquid-to-solid ratio of the long-chain alkylamine solvent to the halide is 1-3:10-20 mL / mg.

6. The method for preparing a Ketjen carbon-supported CuPd binary alloy electrocatalyst as described in claim 5, characterized in that, The long-chain alkylamine solvent is oleylamine; the polyol dispersant is ethylene glycol.

7. The method for preparing a Ketjen carbon-supported CuPd binary alloy electrocatalyst as described in claim 2, characterized in that, In step (1), the temperature of the heating alloying reaction is 140-160℃, the rotation speed is 300-600rpm, and the time is 2-3h.

8. The method for preparing a Ketjen carbon-supported CuPd binary alloy electrocatalyst as described in claim 2, characterized in that, In step (2), the solid-liquid ratio of the CuPd alloy nanoparticles to n-hexane is 2-5:3-7 mg / mL; The mass ratio of the Ketsin carbon to the CuPd alloy nanoparticles is 10-20:2-5.

9. The application of the Ketjen carbon-supported CuPd binary alloy electrocatalyst prepared by the preparation method according to any one of claims 2-8 in electrocatalytic reactions.

10. The application as described in claim 9, characterized in that, The electrocatalytic reaction is a potassium nitrate electrocatalytic reduction reaction, with 0.1M KOH + 0.1M KNO3 as the electrolyte and the Ketjen carbon-supported CuPd binary alloy electrocatalyst as the catalyst.

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