Bark / metal organic framework derived wave-absorbing material and preparation method thereof

Abstract

The invention discloses a bark / metal organic framework derived (TPC / FeCoC) wave-absorbing material and a preparation method thereof, and belongs to the technical field of electromagnetic wave absorbing materials. The TPC / FeCoC wave-absorbing material is composed of tree bark derived porous carbon and metal organic framework Fe-Co-C, the tree bark TPC is in a three-dimensional shape, and FeCoC grows on the surface of the tree bark derived carbon in situ. The TPC / FeCoC has the advantages of high porosity, large specific surface area, small density, light weight, wide absorption frequency band and multiple loss mechanisms.

Description

Technical Field

[0001] The invention relates to a bark / metal organic framework derived absorbing material (TPC / FeCoC) and a preparation method of the material, belonging to the technical field of electromagnetic wave absorbing materials. Background Art

[0002] In recent years, with the rapid development of wireless communication technology, while improving people's quality of life, it has inevitably caused increasingly serious electromagnetic pollution problems. Excessive electromagnetic radiation seriously interferes with the sensitivity of electronic components, endangers human health, and even endangers national security. Therefore, excellent electromagnetic wave absorbing materials with simple manufacturing process, low cost, good impedance matching, and high microwave attenuation loss efficiency are urgently needed. Carbon-based materials have excellent dielectric loss capacity, large specific surface area, light weight, strong corrosion resistance and easy processing. They have been widely studied and applied in the field of electromagnetic wave absorption and are often used to prepare lightweight and high-strength electromagnetic absorbing materials. However, traditional carbon materials such as graphene and carbon fiber have high dielectric constants, poor impedance, complex preparation, high cost and unfriendly to the environment, which limits their application potential in the field of wave absorption. Therefore, it is urgent to develop a new type of carbon material that takes into account low cost, simple preparation process, and meets the development needs of "light, thin, wide and strong" absorbing materials.

[0003] As an electromagnetic wave absorbing material, bark has unique natural microscopic pores, large specific surface area, rich functional groups and heteroatoms, and has great potential in the field of electromagnetic wave absorption. However, the dielectric loss of bark-derived carbon alone cannot meet the requirements of impedance matching, and magnetic materials need to be added to optimize the impedance. Metal organic framework (MOF) is a porous crystalline material that is connected to organic ligands by metal centers. It has the advantages of high specific surface area, controllable structure and high porosity, and is widely popular in the field of electromagnetic wave absorption. Using three-dimensional bark as biomass raw material, the bark is compounded with FeCo-MOF precursor by vacuum impregnation method, and the bark derived porous carbon / FeCo carbon (TPC / FeCoC) composite material obtained by high temperature carbonization is more conducive to obtaining excellent electromagnetic wave absorption ability: on the one hand, the three-dimensional bark derived porous carbon has a large number of pores, which optimizes the impedance matching and prolongs the transmission path of electromagnetic waves; on the other hand, the generated FeCoC is attached to the pores of the porous carbon, which brings a large amount of interface polarization loss and introduces magnetic loss, enriching the loss mechanism of the composite material; at the same time, the defects of the bark derived carbon itself and the nitrogen element bring partial polarization loss, which enhances the composite material's attenuation ability to electromagnetic waves. TPC / FeCoC composite material shows excellent electromagnetic wave absorption ability, has obvious advantages over other carbon-based materials in terms of structural construction and dielectric-magnetic loss synergy, and has broad application prospects in the field of electromagnetic wave absorption.

[0004] Patent CN114568009A discloses a Fe-MOF-derived graphene-based magnetic composite aerogel absorbing material and a preparation method thereof. The main skeleton structure of the composite aerogel absorbing material is a porous aerogel material obtained by in-situ self-assembly of graphene oxide. The Fe-MOF precursor solution is immersed in an ice bath, and then self-assembled, freeze-dried, and carbonized at high temperature to obtain a graphene-based Fe 2 O 3 The cluster magnetic composite aerogel absorber has a minimum reflection loss of -60.31dB and an effective bandwidth of 4.13GHz at a thickness of 4.84mm and a frequency of 8.02GHz. The effective bandwidth at a matching thickness of 3.12mm is 6.76GHz. However, the composite material is relatively thick, and the raw materials such as graphene oxide required for its preparation are expensive. At the same time, the preparation process through freeze-drying technology is cumbersome and difficult to achieve large-scale industrial production.

[0005] Patent CN118108222A discloses a biomass-derived carbon absorbing material using corn silk as raw material and its preparation method. The method washes and dries the raw material corn silk, heat treats it in an argon atmosphere, grinds the product into powder, activates it with a KOH solution, and then heat treats it with argon again to prepare a single-component biomass-derived porous carbon composite material. At a matching thickness of 4.5 mm, the minimum reflection loss at 6.88 GHz is -75 dB. When the thickness is reduced to 2.6 mm, the maximum absorption bandwidth can reach 6.64 GHz. However, the material has a single component, and the dielectric loss it has cannot meet the impedance matching requirements, and it cannot effectively solve the problem of electromagnetic wave pollution.

[0006] Guojuan Ma et al. proposed a BPC-CoFe 2 O 4 / CoFe@ preparation method of multi-level low-frequency microwave absorbing material. The composite material regulates the carrier morphology of celery stem-derived porous carbon through an activation process, presenting a multi-level loose thin-walled microporous morphology. Based on the annealing temperature, the magnetic CoFe 2 O 4 Co-loading and particle size modulation of CoFe. The impedance characteristics of the material are optimized by forming a matching carbon layer on the surface of the CoFe magnetic phase through the carbon thermal diffusion effect. Under the synergistic effect of magnetic resonance, eddy current loss, polarization relaxation and porous scattering effects, the prepared composite material can achieve an electromagnetic absorption intensity of -39.48dB at 1.22GHz, and when the material thickness is only 1.5mm, it reaches a low-frequency effective absorption bandwidth of 2.15GHz. However, the preparation of this composite material requires vacuum calcination, which has extremely high requirements on equipment and cannot be fully met. The preparation process is cumbersome and cannot be achieved in industrial production.

[0007] Jing Deng et al. proposed a method for preparing a nickel / kapok fiber-derived carbon (Ni / C) hollow porous electromagnetic absorbing material in the article "Preparation and Absorption Performance of Nickel / Kapok Fiber-Derived Carbon Composite Materials". The material uses kapok fiber as a precursor, and maintains its original form after alkali treatment, ion recombination and high-temperature carbonization. The rich defect structure on the fiber surface greatly enhances the defect polarization ability of the composite material, giving the composite material better magnetic properties and magnetic loss capacity. The minimum reflection loss value is -52.6dB at 800°C, and the maximum effective bandwidth is 8.32GHz. However, the impedance matching of the material deteriorates with the increase of carbonization temperature, and it cannot meet both good impedance and strong attenuation performance. Therefore, the absorbing performance is not excellent enough, and it is not suitable for applications that pursue high-efficiency absorbing characteristics.

[0008] Ziqi Li et al. proposed a method for preparing Co / C porous chain rod-shaped microwave absorber in the article "Preparation and performance of magnetic metal cobalt / carbon microwave absorber powder". This method uses Co salt and trimesic acid as raw materials and organic ligands, respectively, to prepare Co-based metal organic framework by precipitation method, and synthesizes magnetic metal Co / C composite microwave absorber powder by calcination treatment. The maximum reflection loss and effective absorption bandwidth of this material can reach -35dB and 0.56GHz at a thickness of 4.5mm and a frequency of 13.76GHz, but its electromagnetic absorption performance is weaker than that of existing absorbing materials and cannot meet the requirements of efficient absorption.

[0009] Shun Dong et al. proposed a method for preparing MnOnrs / PBDC flexible porous high-efficiency microwave absorbing materials in the article "Achieving Excellent Electromagnetic Wave Absorption Capabilities by Construction of MnO Nanorods on Porous Carbon Composites Derived from Natural Wood via a Simple Route". This method uses wood as raw material, converts natural wood into porous carbon material by KOH hydrothermal activation and carbonization process, and incorporates MnOnrs into PBDC by hydrothermal method and annealing treatment. The MnOnrs / PBDC composite material has an optimal reflection loss of -51.6dB at a matching thickness of 2.47mm and a frequency of 10.4GHz, and a maximum effective bandwidth of 4.7GHz. However, the content of the composite material in paraffin has reached 30wt%, resulting in a high density in the composite material, which is not suitable for applications that require lightweight characteristics.

[0010] Xuanqi Yang et al. proposed a method for preparing a FeNi / LSC nanosheet array sponge-like electromagnetic wave absorbing material in the article "Customization of FeNi alloy nanosheet arrays insertedwith biomass-derived carbon templates for boosted electromagnetic wave absorption". The composite material uses layered double hydroxide as the precursor of the bimetallic alloy, and combines it with porous biomass-derived carbon materials through simple hydrothermal and carbonization methods to prepare iron-nickel alloy nanosheet array / bacteria spore-derived carbon (FeNi / LSC). FeNi / LSC has ideal electromagnetic wave absorption performance. When the filler content is 20wt%, the minimum reflection loss at a thickness of 1.5mm is -58.3dB, and the effective absorption bandwidth is 4.92GHz. However, during the preparation of this material, the excessively high carbonization temperature can easily lead to the melting and recrystallization of the FeNi alloy nanosheet array, forming large particles, thereby reducing the electromagnetic wave absorption performance of the material. The carbonization temperature needs to be strictly controlled, and the production equipment and process technology are required to be high.

[0011] At present, existing research mainly focuses on the fields of biomass and iron, nickel, and cobalt metal organic framework derivatives, but due to factors such as production process and output, it is impossible to achieve industrial application. At the same time, some biomass-derived carbon materials cannot simultaneously meet good impedance and strong attenuation performance under existing theories, and are not suitable for occasions requiring high-efficiency wave absorption characteristics. Increasing the amount of biomass-derived carbon materials can achieve better wave absorption effects, but it is not suitable for lightweight occasions. Therefore, developing a biomass-derived carbon wave absorbing material with low cost, simple preparation process, green and environmental protection, and meeting the development needs of "light, thin, wide, and strong" is of great significance to solving electromagnetic pollution problems and improving people's happiness index. Summary of the invention

[0012] The purpose of the present invention is to provide a bark / metal organic framework derived electromagnetic absorbing material and a preparation method thereof. The electromagnetic absorbing material has unique natural microscopic pores, large specific surface area, controllable structure, rich loss mechanism, wide absorption frequency band, light weight, low density, and can be produced and applied on a large scale.

[0013] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0014] A bark / metal organic framework derived electromagnetic absorbing material, the electromagnetic absorbing material is composed of bark derived porous carbon and metal organic framework iron cobalt carbon, the bark derived carbon is three-dimensional, and the iron cobalt carbon grows in situ on the surface of the bark derived carbon.

[0015] A method for preparing the above-mentioned bark / metal organic framework derived absorbing material, the method comprising the following steps:

[0016] Step 1: Preparation of pretreated bark-derived carbon: Weigh an appropriate amount of bark, wash off the surface impurities with deionized water and dry it, place the dried bark in a tubular furnace, and pyrolyze it under a nitrogen atmosphere to finally obtain pretreated bark-derived carbon; the purpose of using deionized water is to preliminarily clean the impurities on the surface of the bark so that the impurities can be further removed. The purpose of passing nitrogen is to fluidize the bark and fully contact it with the heating surface, thereby improving the heat transfer efficiency. After pyrolysis in the tubular furnace, impurities in the bark are removed and tiny pores are generated to ensure that there are no impurities attached to the surface of the pores, which is conducive to the injection of the mixed solution.

[0017] Step 2: Preparation of bark / FeCo-MOF precursor: Metal salt Co(NO 3 ) 2 6H 2 O, metal salt Fe(NO 3 ) 3 9H 2 O is dissolved in deionized water to obtain solution A. Then 2-methylimidazole is dissolved in deionized water to obtain solution B. The bark obtained in step 1 is stirred and immersed in solution A and solution B respectively by vacuum impregnation, and after sufficient stirring, a bark / FeCo-MOF precursor is obtained; the purpose of using 2-methylimidazole is to solidify bark-derived carbon as a ligand, and react with metal salts to obtain FeCo-MOF precursor. The purpose of vacuum impregnation and stirring is to fully fill the pores of the bark with the solution, which is conducive to the uniform distribution of metal salts on the surface of the bark.

[0018] Step 3: Preparation of TPC / FeCoC composite material: After drying the bark / FeCo-MOF precursor obtained in step 2, put it into a tubular furnace and carbonize it at high temperature under a nitrogen atmosphere to obtain a TPC / FeCoC composite material.

[0019] Furthermore, in step 1, the mass of the bark is 0.1 to 50 g.

[0020] Furthermore, in step 1, the bark is dried at a temperature of 40 to 100° C. and for a drying time of 1 to 24 hours.

[0021] Furthermore, in step 1, the temperature of the tubular furnace pyrolysis is 200-1000° C., the rising rate is 1-18° C. / min, and the insulation time is 0.1-5 h.

[0022] Furthermore, in step 2, the mass ratio of the bark-derived carbon to the mixed salt solution is 1:0.1 to 1:100.

[0023] Furthermore, in step 2, the metal salt Co(NO3 ) 2 6H 2 O mass is 0.1137~5.2684g, metal salt Fe(NO 3 ) 3 9H 2 The mass of O is 0.1516~7.0245g, and the volume of deionized water is 10~200mL.

[0024] Furthermore, in step 2, the mass of the 2-methylimidazole is 1.8266-10.2401 g, and the volume of deionized water is 10-200 mL.

[0025] Furthermore, in step 2, the bark is stirred in solution A for 1 to 24 hours, and in solution B for 1 to 24 hours.

[0026] Furthermore, in step 3, the drying temperature of the bark precursor is 30 to 100° C., and the drying time is 1 to 24 hours.

[0027] Furthermore, in step 3, the temperature of the tube furnace is 200-1000° C., the rising rate is 0.2-15° C. / min, and the holding time is 0.1-5 h.

[0028] The beneficial effects of the present invention compared to the prior art are:

[0029] (1) The unique pore structure of the TPC / FeCoC composite absorber of the present invention optimizes impedance matching and prolongs the transmission path of electromagnetic waves. The magnetic FeCoC is attached to the pores of the porous carbon, which optimizes the loss mechanism. The bark-derived carbon itself has defects, and the nitrogen element brings partial polarization loss, which makes it have excellent electromagnetic wave absorption performance.

[0030] (2) The TPC / FeCoC composite absorbing material of the present invention has a minimum reflection loss of -61.04 dB and an effective bandwidth of 7.25 GHz in the frequency range of 2-18 GHz when the doping amount is 20% and the thickness is 2.64 mm.

[0031] (3) The TPC / FeCoC composite absorbing material of the present invention has the characteristics of being porous and low-density. The large porosity reduces the density of the absorber, better realizes the preparation and application of lightweight absorbers, and is conducive to the preparation of lightweight high-strength electromagnetic absorbing materials.

[0032] (4) The present invention uses bark widely existing in nature as raw material, obtains bark-derived carbon by pyrolysis, further obtains bark / FeCo-MOF precursor by vacuum impregnation, and prepares TPC / FeCoC composite material by high-temperature carbonization. The composite material has low cost, simple preparation process, and is green and environmentally friendly, meeting the development needs of new carbon materials of "light, thin, wide, and strong". BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 XRD spectrum of the TPC / FeCoC composite absorbing material prepared in Example 1 of the present invention;

[0034] Figure 2 This is a SEM photo of the TPC / FeCoC composite absorbing material prepared in Example 1 of the present invention;

[0035] Figure 3 This is a reflection loss diagram of the TPC / FeCoC composite absorbing material prepared in Example 1 of the present invention;

[0036] Figure 4 This is a SEM photo of the TPC / FeCoC composite absorbing material prepared in Example 2 of the present invention;

[0037] Figure 5 This is a reflection loss diagram of the TPC / FeCoC composite absorbing material prepared in Example 2 of the present invention;

[0038] Figure 6 This is a SEM photo of the TPC / FeCoC composite absorbing material prepared in Example 3 of the present invention;

[0039] Figure 7 This is a reflection loss diagram of the TPC / FeCoC composite absorbing material prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0040] The technical solutions in the present invention will be described clearly and completely in conjunction with the embodiments below. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work belong to the scope of protection of the present invention. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0041] Example 1

[0042] A method for preparing a bark / metal organic framework derived (TPC / FeCoC) absorbing material specifically comprises the following steps:

[0043] Step 1: Weigh an appropriate amount of bark, rinse it with deionized water, dry it at 50°C for 2h, then put it into a tubular furnace for pyrolysis, increase the temperature to 700°C at a rate of 10°C / min under a nitrogen atmosphere, and keep it warm for 1h to obtain pretreated bark-derived carbon.

[0044] Step 2: Weigh 0.873 g of cobalt nitrate hexahydrate (Co(NO 3 ) 2 6H 2 O) and 1.212 g of iron nitrate nonahydrate (Fe(NO 3 ) 3 9H 2 O) was dissolved in 20 mL of deionized water, stirred evenly to form a mixed salt solution. Weigh 2.948 g of 2-methylimidazole and dissolve it in 80 mL of deionized water, stir evenly to form a 2-methylimidazole solution. Take 0.063 g of pretreated bark-derived carbon and immerse it in the mixed salt solution by vacuum impregnation (the mass ratio of bark-derived carbon: mixed salt solution is 1:20), and stir for 12 hours. Then immerse the bark in the 2-methylimidazole solution by vacuum impregnation and stir for 12 hours to obtain the bark / FeCo-MOF precursor.

[0045] Step 3: Dry the bark / FeCo-MOF precursor at 50°C for 2 h, then place it in a tubular furnace, heat it to 700°C at a heating rate of 1°C / min under nitrogen protection, keep it warm for 2 h, and finally carbonize it at high temperature to obtain the TPC / FeCoC composite material.

[0046] Example 2

[0047] A method for preparing a bark / metal organic framework derived (TPC / FeCoC) absorbing material specifically comprises the following steps:

[0048] Step 1: Weigh an appropriate amount of bark, rinse it with deionized water, dry it at 50°C for 2h, then put it into a tubular furnace for pyrolysis, increase the temperature to 700°C at a rate of 10°C / min under a nitrogen atmosphere, and keep it warm for 1h to obtain pretreated bark-derived carbon.

[0049] Step 2: Weigh 0.873 g of cobalt nitrate hexahydrate (Co(NO 3 ) 2 6H 2 O) and 1.212 g of iron nitrate nonahydrate (Fe(NO 3 ) 3 9H 2 O) was dissolved in 20 mL of deionized water, stirred evenly to form a mixed salt solution. Weigh 2.948 g of 2-methylimidazole and dissolve it in 80 mL of deionized water, stir evenly to form a 2-methylimidazole solution. Take 0.038 g of pretreated bark-derived carbon and immerse it in the mixed salt solution by vacuum impregnation (the mass ratio of bark-derived carbon: mixed salt solution is 3:100), and stir for 12 hours. Then immerse the bark in the 2-methylimidazole solution by vacuum impregnation and stir for 12 hours to obtain the bark / FeCo-MOF precursor.

[0050] Step 3: Dry the bark / FeCo-MOF precursor at 50°C for 2 h, then place it in a tubular furnace, heat it to 700°C at a heating rate of 1°C / min under nitrogen protection, keep it warm for 2 h, and finally carbonize it at high temperature to obtain the TPC / FeCoC composite material.

[0051] Example 3

[0052] A method for preparing a bark / metal organic framework derived (TPC / FeCoC) absorbing material specifically comprises the following steps:

[0053] Step 1: Weigh an appropriate amount of bark, rinse it with deionized water, dry it at 50°C for 2h, then put it into a tubular furnace for pyrolysis, increase the temperature to 700°C at a rate of 10°C / min under a nitrogen atmosphere, and keep it warm for 1h to obtain pretreated bark-derived carbon.

[0054] Step 2: Weigh 0.873 g of cobalt nitrate hexahydrate (Co(NO 3 ) 2 6H 2 O) and 1.212 g of iron nitrate nonahydrate (Fe(NO 3 ) 3 9H 2 O) was dissolved in 20 mL of deionized water, stirred evenly to form a mixed salt solution. Weigh 2.948 g of 2-methylimidazole and dissolve it in 80 mL of deionized water, stir evenly to form a 2-methylimidazole solution. Take 0.127 g of pretreated bark-derived carbon and immerse it in the mixed salt solution by vacuum impregnation (the mass ratio of bark-derived carbon: mixed salt solution is 1:10), and stir for 12 hours. Then immerse the bark in the 2-methylimidazole solution by vacuum impregnation and stir for 12 hours to obtain the bark / FeCo-MOF precursor.

[0055] Step 3: Dry the bark / FeCo-MOF precursor at 50°C for 2 h, then place it in a tubular furnace, heat it to 700°C at a heating rate of 1°C / min under nitrogen protection, keep it warm for 2 h, and finally carbonize it at high temperature to obtain the TPC / FeCoC composite material.

[0056] Figure 1 The XRD spectrum of the TPC / FeCoC composite absorbing material prepared in Example 1 is shown in FIG. Figure 1 A broad diffraction peak can be found at 2θ=25°, corresponding to the (002) crystal plane of graphitic carbon. After the introduction of FeCo, a broad diffraction peak at 2θ=111° corresponds to the (111) crystal plane of FeCo, proving that FeCo was successfully grown in situ on the bark-derived carbon surface.

[0057] Figure 2 This is the SEM image of the TPC / FeCoC composite absorbing material prepared in Example 1. Figure 2 It can be observed that the carbonized bark still maintains a tightly arranged parallel cell-like pore wall structure, and the FeCo particles are densely and evenly attached to the cell wall.

[0058] Figure 3 This is the reflection loss diagram of the TPC / FeCoC composite absorbing material prepared in Example 1. When the mass ratio of the composite material of bark-derived carbon: mixed salt solution is 1:20, at a thickness of 2.64 mm, the effective bandwidth is 7.25 GHz (10.19 GHz-17.44 GHz), and the maximum absorption effect of -61.04 dB is achieved at 12.23 GHz.

[0059] Figure 4 This is the SEM image of the TPC / FeCoC composite absorber prepared in Example 2. Figure 4 It can be observed that the carbonized bark still maintains a closely arranged parallel cell-like pore wall structure, but compared with Example 1, the FeCo particles attached to the cell wall surface are sparser.

[0060] Figure 5 This is the reflection loss diagram of the TPC / FeCoC composite absorber prepared in Example 2. Figure 5 It can be seen that when the mass ratio of bark-derived carbon: mixed salt solution is 3:100, the microwave absorption effect of the composite material is poor. At a thickness of 6 mm, the optimal reflection loss is -13.85 dB, and the maximum effective bandwidth at 16.46 GHz is only 3.06 GHz. Its electromagnetic absorption effect is quite different from that of Example 1.

[0061] Figure 6 This is the SEM image of the TPC / FeCoC composite absorber prepared in Example 3. Figure 6 It can be observed that the addition of excess Fe 3+ 、Co 2+ Afterwards, the particles agglomerate in large quantities, blocking the pores on the surface of the material.

[0062] Figure 7 This is the reflection loss diagram of the TPC / FeCoC composite absorber prepared in Example 3. Figure 7 It can be seen that when the mass ratio of bark-derived carbon: mixed salt solution is 1:10, excessive FeCoC agglomerates and blocks the cell pores, resulting in impedance mismatch, with a minimum reflection loss value of only -25.62 dB at a thickness of 2 mm and a maximum effective bandwidth of 3.76 GHz at 17.21 GHz.

[0063] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A bark / metal organic framework derived absorbing material, characterized in that: The electromagnetic wave absorbing material consists of bark-derived porous carbon and metal organic framework iron-cobalt carbon. The bark-derived carbon is three-dimensional, and the iron-cobalt carbon grows in situ on the surface of the bark-derived carbon.

2. A method for preparing the bark / metal organic framework derived absorbing material according to claim 1, characterized in that: The method comprises the following steps: Step 1: preparing pretreated bark-derived carbon: weighing an appropriate amount of bark, washing the surface impurities with deionized water and drying the bark, placing the dried bark in a tubular furnace, and pyrolyzing the bark in a nitrogen atmosphere to finally obtain pretreated bark-derived carbon; Step 2: Preparation of bark / FeCo-MOF precursor: Dissolve metal salt Co(NO3)2·6H2O and metal salt Fe(NO3)3·9H2O in deionized water to obtain solution A. Then dissolve 2-methylimidazole in deionized water to obtain solution B. The bark obtained in step 1 is immersed in solution A and solution B by vacuum impregnation, and after sufficient stirring, a bark / FeCo-MOF precursor is obtained; Step 3: Preparation of TPC / FeCoC composite material: After drying the bark / FeCo-MOF precursor obtained in step 2, put it into a tubular furnace and carbonize it at high temperature under a nitrogen atmosphere to obtain a TPC / FeCoC composite material.

3. The method for preparing the bark / metal organic framework derived absorbing material according to claim 2, characterized in that: In step 1, the mass of the bark is 0.1 to 50 g.

4. The method for preparing the bark / metal organic framework derived absorbing material according to claim 2, characterized in that: In step 1, the bark is dried at a temperature of 40 to 100° C. and for a drying time of 1 to 24 hours.

5. The method for preparing the bark / metal organic framework derived absorbing material according to claim 2, characterized in that: In step 1, the temperature of the tubular furnace pyrolysis is 200-1000° C., the rising rate is 1-18° C. / min, and the insulation time is 0.1-5 h.

6. The method for preparing the bark / metal organic framework derived absorbing material according to claim 2, characterized in that: In step 2, the mass ratio of the bark-derived carbon to the mixed salt solution is 1:0.1 to 1:

100.

7. The method for preparing the bark / metal organic framework derived absorbing material according to claim 2, characterized in that: In step 2, the mass of the metal salt Co(NO3)2·6H2O is 0.1137-5.2684 g, the mass of the metal salt Fe(NO3)3·9H2O is 0.1516-7.0245 g, and the volume of deionized water is 10-200 mL.

8. The method for preparing the bark / metal organic framework derived absorbing material according to claim 2, characterized in that: In step 2, the mass of 2-methylimidazole is 1.8266-10.2401 g, and the volume of deionized water is 10-200 mL.

9. The method for preparing the bark / metal organic framework derived absorbing material according to claim 2, characterized in that: In step 2, the bark is stirred in solution A for 1 to 24 hours, and in solution B for 1 to 24 hours.

10. The method for preparing the bark / metal organic framework derived absorbing material according to claim 2, characterized in that: In step 3, the drying temperature of the bark precursor is 30 to 100° C., and the drying time is 1 to 24 hours.

11. The method for preparing the bark / metal organic framework derived absorbing material according to claim 2, characterized in that: In step 3, the temperature of the tube furnace is 200-1000° C., the rising rate is 0.2-15° C. / min, and the insulation time is 0.1-5 h.

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