A carbon-platinum-cobalt composite material and its preparation method

Abstract

This invention relates to a carbon-platinum-cobalt composite material, PtCo-C, and its preparation method. The composite material consists of a carbon framework with a dodecahedral structure and PtCo nanoparticles. A cobalt-based precursor was prepared based on a metal-organic framework (MOF) material. A composite material with PtCo nanoparticles supported on a porous carbon matrix was prepared using a simple chemical reduction method. The cobalt-based precursor has a regular polyhedral structure, and the cobalt nanoparticles are uniformly dispersed in the porous carbon framework. PtCo-C material is prepared without a reducing agent. The uniform dispersion of PtCo particles in the porous carbon matrix prevents the agglomeration of nanoparticles during the reaction process, thereby improving the material's performance. The material preparation process is simple, exhibits good ethylene removal efficiency, and has significant potential for widespread application.

Description

Technical Field

[0001] This invention relates to a carbon-platinum-cobalt composite material PtCo-C, its preparation method, and its application in ethylene removal. Background Technology

[0002] With the continuous development of my country's national economy and the continuous improvement of people's living standards, the consumption of vegetables and fruits has been increasing year by year. This indicates that the supply and consumption of fruits and vegetables will usher in a bumper year, and people's requirements for the quality of fruits and vegetables will become increasingly stringent. During the storage and transportation of harvested fruits and vegetables, the ripening hormone ethylene has a significant impact on their respiration; even a concentration of one part per thousand can induce premature ripening and aging. Measures for further preservation of fruits and vegetables are being improved, and the use of ethylene removal agents is becoming increasingly common, with a growing variety of ethylene removal agents available. Research has found that porous carbon materials composite platinum-based bimetals can adsorb ethylene at room temperature while simultaneously using ultraviolet light under sunlight to convert trace amounts of ethylene into carbon dioxide and water, reducing the impact of ethylene on fruit plants. Summary of the Invention

[0003] The purpose of this invention is to provide a carbon-platinum-cobalt composite material, PtCo-C, which is composed of a carbon skeleton with a dodecahedral structure and PtCo nanoparticles.

[0004] This invention prepares a cobalt-based precursor based on metal-organic framework (MOF) materials, and then uses a simple chemical reduction method to prepare a composite material of PtCo nanoparticles supported on a porous carbon matrix. The cobalt-based precursor has a regular polyhedral structure, with the cobalt nanoparticles uniformly dispersed in the porous carbon framework. This structure ensures that the platinum-based active material particles are uniformly dispersed in the porous carbon matrix after the chemical reduction reaction, preventing the agglomeration of nanoparticles during the reaction process, thereby improving the material's performance.

[0005] The preparation method of the bimetallic phosphide composite material of the present invention is carried out according to the following steps:

[0006] 1) Weigh Co(NO3)2·6H2O and 2-methylimidazole at a mass ratio of 1:1-3, and then dissolve them separately in 100 ml of methanol. After stirring and dissolving, pour the 2-methylimidazole solution into the Co(NO3)2 solution and stir. After stopping stirring, age at room temperature for 24 h. Then, centrifuge the product, wash and dry it to obtain a cobalt-based metal-organic framework compound with a dodecahedral structure.

[0007] 2) The cobalt-based metal-organic framework compound obtained in step 1) is placed in a quartz boat and then placed in a tube furnace. The temperature is raised to 550-900℃ under an argon atmosphere and held for 1-8 hours to obtain a dodecahedral porous carbon composite material Co-C containing cobalt metal.

[0008] 3) Add the Co-C composite material obtained in step 2) to H2PtCl4 solution without adding any reducing agent, perform ultrasonic stirring, and after a certain reaction time, wash and dry to obtain PtCo-C composite material.

[0009] The cleaning and drying process described in step 1) involves washing the product with methanol three times, followed by vacuum drying at 60°C for 8 hours.

[0010] The heating described in step 2) is to raise the temperature to 600°C at a heating rate of 5°C / min and hold it at that temperature for 2 hours.

[0011] The concentration of the H2PtCl4 solution mentioned in step 3) is 0.05 mol / L.

[0012] The method of the present invention has the following characteristics:

[0013] (1) A dodecahedral porous carbon matrix material containing cobalt was obtained by carbonizing a cobalt-based metal-organic framework compound with a dodecahedral structure, and the PtCo active material particles were uniformly dispersed in the porous carbon matrix.

[0014] (2) PtCo-C materials are prepared by spontaneous in-situ reaction without the use of external reducing agents, and the preparation process is simple and has good application value. Attached Figure Description

[0015] Figure 1 The image shows the XRD pattern of the PtCo-C composite material obtained in Example 1.

[0016] Figure 2 The image shows a SEM image of the PtCo-C composite material obtained in Example 1.

[0017] Figure 3 The graph shows a comparison of ethylene changes in a fruit storage box when the PtCo-C material obtained in Example 1 is added, when the Co-C material obtained in Comparative Example 1 is added, and when no material is added.

[0018] Figure 4 The preservation time of bananas in a polyethylene sealed packaging bag was measured by adding PtCo-C material (Example 1), Co-C material (Comparative Example 1), and activated carbon (Comparative Example 2) to a polyethylene sealed packaging bag, and by adding bananas in a simple polyethylene packaging bag. Detailed Implementation

[0019] Example 1

[0020] 1) Weigh 0.498g Co(NO3)2·6H2O and 0.656g 2-methylimidazole, dissolve them separately in 50ml methanol, stir for 10 minutes, and after stirring and dissolving, quickly pour the 2-methylimidazole solution into the Co(NO3)2 solution, continue stirring for 10 minutes, stop stirring and age at room temperature for 24 hours, then centrifuge the product, wash it 3 times with methanol, and finally dry it under vacuum at 60℃ for 8 hours to obtain a cobalt-based metal-organic framework compound with a dodecahedral structure.

[0021] 2) A cobalt-based metal-organic framework compound with a dodecahedral structure was placed in a quartz boat and placed in a tube furnace. The temperature was increased from room temperature to the target temperature of 600℃ at a heating rate of 5℃ / min under an argon atmosphere and held constant for 2 hours to obtain a dodecahedral porous carbon composite material Co-C containing cobalt metal.

[0022] 3) Place 50 mg of the prepared composite material Co-C in 10 ml of deionized water and sonicate until uniform and free of precipitate. Add it to 10 ml of H2PtCl4 solution with a concentration of 0.05 mol / L and stir until uniform. After standing for 12 h, wash with ethanol and deionized water and dry. Collect the particles and vacuum dry at 60 °C for 24 h to obtain PtCo-C powder.

[0023] Example 2

[0024] 1) Synthesis of cobalt-based metal-organic framework compounds with dodecahedral structure: Weigh 1g Co(NO3)2·6H2O and 3g 2-methylimidazole, dissolve them separately in 800ml methanol, stir for 10 minutes, and after stirring and dissolving, quickly pour the 2-methylimidazole solution into the Co(NO3)2 solution, continue stirring for 10 minutes, stop stirring and age at room temperature for 12 hours, then centrifuge the product, wash it 3 times with methanol, and finally dry it under vacuum at 60℃ for 12 hours to obtain cobalt-based metal-organic framework compounds with dodecahedral structure.

[0025] 2) A cobalt-based metal-organic framework compound with a dodecahedral structure was placed in a quartz boat and placed in a tube furnace. The temperature was increased from room temperature to the target temperature of 800℃ at a heating rate of 5℃ / min under an argon atmosphere and held constant for 4h to obtain a dodecahedral porous carbon composite material Co-C containing cobalt metal.

[0026] 3) Place 50 mg of the prepared composite material Co-C in 10 ml of deionized water and sonicate until uniform and free of precipitate. Add it to 10 ml of 0.05 mol / L H2PtCl4 solution and stir until uniform. Add sodium borohydride and let stand for 12 h. Wash with ethanol and deionized water and dry. Collect the particles and vacuum dry at 60 °C for 24 h to obtain the PtCo-C composite material.

[0027] Comparative Example 1

[0028] 1) Weigh 0.498g Co(NO3)2·6H2O and 0.656g 2-methylimidazole, dissolve them separately in 50ml methanol, stir for 10 minutes, and after stirring and dissolving, quickly pour the 2-methylimidazole solution into the Co(NO3)2 solution, continue stirring for 10 minutes, stop stirring and age at room temperature for 24 hours, then centrifuge the product, wash it 3 times with methanol, and finally dry it under vacuum at 60℃ for 8 hours to obtain a cobalt-based metal-organic framework compound with a dodecahedral structure.

[0029] 2) A cobalt-based metal-organic framework compound with a dodecahedral structure was placed in a quartz boat and placed in a tube furnace. The temperature was increased from room temperature to the target temperature of 600℃ at a heating rate of 5℃ / min under an argon atmosphere and held constant for 2 hours to obtain a dodecahedral porous carbon composite material Co-C containing cobalt metal.

[0030] Comparative Example 2

[0031] Commercially available specific surface area ≥850m² 2 / g of powdered activated carbon.

[0032] Performance testing:

[0033] The material obtained in Example 1 was characterized, and its performance was tested compared with that of Comparative Example 1. Powder X-ray diffraction (XRD) patterns were obtained using a Bruker D8 Advance instrument. Scanning electron microscopy (SEM) images were acquired using a Hitachi SU8020. Transmission electron microscopy (TEM) images were acquired using a JEM 1200EX. Bananas of the same variety, from the same batch, with similar size, firmness, color, and maturity were selected as test samples at room temperature. Five bananas were placed in each group, weighing approximately 600g-750g, and placed in a 45*25*35cm transparent sealed box. 15mg of PtCo-C material was placed on a 5*5cm piece of Xuan paper inside the transparent sealed box, and the ethylene change in the sealed environment was detected using an EST-2000 handheld gas detector. Bananas with similar peel condition and color, suitable and similar odor and firmness were selected to ensure consistency in maturity. They also had similar overall shape, weight, and size, and were free from mechanical damage and pests / diseases as experimental materials. Commercially available ordinary polyethylene preservation bags were used to seal and preserve each group of bananas, as well as those from Example 1, Comparative Example 1, and Comparative Example 2, to observe the effect of different materials on the preservation time of bananas at room temperature.

[0034] Figure 1 The image shows the XRD pattern of the PtCo-C composite material obtained in Example 1. The image clearly shows Pt and Co diffraction peaks. Additionally, C diffraction peaks are also present in the image.

[0035] Figure 2The image shows a SEM image of the PtCo-C composite material obtained in Example 1. As can be seen from the image, the PtCo-C composite material obtained from the reaction maintains its dodecahedral structure, without any structural collapse or particle agglomeration.

[0036] Figure 3 The graph shows the changes in ethylene levels in fruit storage boxes containing PtCo-C material, Co-C material, and the control group (without any material). The graph shows that the total ethylene content in the fruit storage box containing PtCo-C ethylene removal agent is lower and decreases more rapidly. In contrast, the total ethylene content in the fruit storage boxes containing Co-C material and the control group is higher, and the decrease is not as rapid as in the PtCo-C material group. This indicates that the added PtCo-C material has a better inhibitory effect on ethylene.

[0037] Figure 4 The preservation time of bananas in Example 1 (PtCo-C material), Comparative Example 1 (Co-C material), and Comparative Example 2 (activated carbon) were compared between PtCo-C material and activated carbon material in polyethylene sealed packaging bags, and bananas in simple polyethylene packaging bags. At room temperature, bananas packaged with PtCo-C material could be preserved for up to 10 days, those packaged with Co-C and activated carbon materials for 6 days, and those packaged in simple polyethylene bags for 5 days.

Claims

1. Use of a carbon-platinum cobalt composite material, characterized in that: This carbon-platinum-cobalt composite material is applied in the field of ethylene removal; The carbon-platinum-cobalt composite material is composed of a carbon framework with a dodecahedral structure and PtCo nanoparticles, and its preparation method is as follows: 1) Synthesis of cobalt-based metal-organic framework compound with dodecahedral structure: Weigh 1g Co(NO3)2·6H2O and 3g 2-methylimidazole, dissolve them in 800ml methanol, stir for 10 minutes, and after stirring and dissolving, quickly pour the 2-methylimidazole solution into the Co(NO3)2 solution, continue stirring for 10 minutes, stop stirring and age at room temperature for 12 hours, then centrifuge the product, wash it 3 times with methanol, and finally dry it under vacuum at 60℃ for 12 hours to obtain cobalt-based metal-organic framework compound with dodecahedral structure; 2) A cobalt-based metal-organic framework compound with a dodecahedral structure was placed in a quartz boat and placed in a tube furnace. The temperature was increased from room temperature to the target temperature of 800℃ at a heating rate of 5℃ / min under an argon atmosphere and held constant for 4h to obtain a dodecahedral porous carbon composite material Co-C containing cobalt metal. 3) Place 50 mg of the prepared composite material Co-C in 10 ml of deionized water and sonicate until uniform and free of precipitate. Add it to 10 ml of 0.05 mol / L H2PtCl4 solution and stir until uniform. Add sodium borohydride and let stand for 12 h. Wash with ethanol and deionized water and dry. Collect the particles and vacuum dry at 60 °C for 24 h to obtain the PtCo-C composite material.

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