Hair-based biomass carbon nanotube and preparation method and application thereof

Abstract

The application discloses a hair-based biomass carbon nanotube and a preparation method and application thereof. The hair-based biomass carbon nanotube is prepared by the following method: after washing and drying yak hair, steam flash explosion treatment is carried out to obtain hair-based biomass charcoal; then, the biomass charcoal is mixed with potassium hydroxide and hydrogen peroxide, and under the protection of inert gas, heat preservation reaction is carried out at 600 DEG C to 750 DEG C, and after washing and drying, the hair-based biomass carbon nanotube is obtained. The carbon nanotube has an internal porous structure and a tube diameter of 13 nm to 150 nm. When the carbon nanotube is used as an electrode material of a super capacitor, the specific capacitance can reach 225 F / g at a current density of 0.5 A / g, the energy density is 31.25 Wh / kg, the power density is 250 W / kg, the coulombic efficiency is close to 100%, and the rate performance is good. The application uses the solid waste yak hair in the animal husbandry as a raw material, does not need to add a metal catalyst, has a mild process and low cost, realizes high-value utilization of biomass waste, and has a wide application prospect in the field of electrochemical energy storage.

Description

Technical Field

[0001] This invention belongs to the field of energy materials and electrochemical energy storage technology, specifically relating to a hair-based biomass carbon nanotube, its preparation method, and its application. Background Technology

[0002] Supercapacitors, as a novel energy storage device, possess advantages such as high power density, long cycle life, and fast charge / discharge speed, and have broad application prospects in portable electronic devices, hybrid vehicles, and grid energy storage. Electrode materials are the core determinant of supercapacitor performance, with carbon-based materials attracting significant attention due to their high specific surface area, excellent conductivity, and chemical stability. Currently, commercial supercapacitor electrode materials mainly consist of activated carbon, carbon nanotubes, and graphene. However, the preparation cost of high-performance carbon nanotubes is high, and they often rely on fossil fuel derivatives as precursors, which does not meet the requirements of green and sustainable development.

[0003] Biomass carbon nanotubes are carbon nanotube materials prepared from biomass and its waste through specific processes. Compared with traditional chemical vapor deposition (CVD), the biomass route has advantages such as renewable raw materials, low cost, and environmental friendliness. In existing technologies, the preparation of biomass carbon nanotubes mainly focuses on plant-based biomass (such as lignin, cellulose, and straw). The preparation process typically requires high temperatures (above 1000℃) and the assistance of transition metal catalysts (such as Fe, Co, and Ni), which not only results in high energy consumption and complex processes, but also the potential for environmental pollution and decreased material purity due to the introduction of metal catalysts.

[0004] On the other hand, livestock production generates a large amount of hair-related waste, such as yak hair, wool, and chicken feathers. These hairs are rich in carbon, possess a natural fibrous structure and nitrogen-containing functional groups, making them ideal precursors for carbon materials. However, the resource utilization rate of hair-related waste is currently low, with most being landfilled or incinerated, causing environmental pollution and resource waste. Previous studies have reported the use of hair to prepare activated carbon for water treatment adsorption (e.g., Chinese patent CN119075918B discloses a magnetic cow hair-based biomass activated carbon and its preparation method and application), but these materials are mainly used for adsorbing dyes and antibiotics; there are no reports of converting hair into carbon nanotubes and applying them to supercapacitor electrode materials.

[0005] Therefore, developing a method for preparing biomass carbon nanotubes using hair waste as raw material without the need for external metal catalysts and under low-temperature conditions, and applying it to supercapacitor electrode materials, is of great significance for realizing the high-value utilization of livestock solid waste, reducing the cost of supercapacitor electrode materials, and promoting the development of green energy storage technology. Summary of the Invention

[0006] The purpose of this invention is to provide a hair-based biomass carbon nanotube, its preparation method and application, in order to solve the problems of high preparation temperature, dependence on metal catalysts and low resource utilization rate of hair waste in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A hair-based biomass carbon nanotube, its preparation method, and its application.

[0008] Furthermore, the hair-based biomass carbon nanotubes have a diameter of 13~150 nm and an internal porous structure.

[0009] Furthermore, the hair-based biomass carbon nanotubes are prepared by a method comprising the following steps: (1) Carbonization: The hair raw material is cleaned and dried, and then treated under steam flash explosion conditions to obtain hair-based biochar; (2) Preparation of carbon nanotubes: The hair-based biochar obtained in step (1) is mixed with potassium hydroxide and hydrogen peroxide, and heated to 600℃~750℃ under inert gas protection for heat preservation reaction, and then cooled down; (3) Washing: Wash the product obtained in step (2) until neutral, and dry it to obtain the hair-based biomass carbon nanotubes.

[0010] Furthermore: In step (1), the pressure of the steam flash explosion is 1.5 MPa and the processing time is 150 s.

[0011] In step (1), the hair is yak hair.

[0012] In step (2), the mass ratio of hair-based biochar to KOH is 1:2 to 1:4.

[0013] In step (2), the concentration of hydrogen peroxide is 30%, and the amount used is 300 μL to 900 μL per 1 g of hair-based biochar.

[0014] In step (2), the heating rate is 5°C / min, and the holding time is 1 hour.

[0015] In step (3), 5% hydrochloric acid is used for neutralization and washing, and then ultrapure water is used for rinsing until neutral.

[0016] The application of hair-based biomass carbon nanotubes in the preparation of supercapacitor electrode materials according to the present invention is tested by the following electrochemical performance testing method: the carbon nanotubes are mixed with conductive agent and binder in a certain proportion to form an electrode sheet, and a three-electrode system is used to perform cyclic voltammetry test and constant current charge-discharge test in electrolyte.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes yak hair, a solid waste product from animal husbandry, to successfully prepare carbon nanotubes with a one-dimensional nanostructure. These nanotubes are then applied to supercapacitor electrode materials, filling a technological gap in the application of hair-based biomass in electrochemical energy storage. This invention employs the synergistic effect of KOH and H₂O₂ to induce in-situ growth of carbon nanotubes at a relatively low temperature of 600℃~750℃, eliminating the need for external transition metal catalysts (Fe, Co, Ni, etc.). This avoids the high energy consumption and environmental pollution problems associated with the high temperatures (above 1000℃) and metal catalysts of traditional chemical vapor deposition methods. Yak hair is one of the main solid waste products from animal husbandry in Northwest China, with low or even negative cost, making its transformation into high-value-added carbon nanotube materials a viable solution. The hair-based biomass carbon nanotubes prepared by this invention possess an internal porous structure and a suitable diameter distribution (13~150 nm). When used as a supercapacitor electrode material, they exhibit a specific capacitance of 225 F / g at a current density of 0.5 A / g, an energy density of 31.25 Wh / kg, a power density of 250 W / kg, a coulombic efficiency close to 100%, and excellent rate performance, demonstrating great potential as a high-performance energy storage electrode material. Furthermore, this invention requires only three steps: carbonization, mixing heat treatment, and cleaning. It has low equipment requirements, is simple to operate, and uses mild reaction conditions, making it suitable for large-scale production. Attached Figure Description

[0018] Figure 1 The image shows the energy dispersive X-ray spectrum of the carbonized yak hair product prepared in Example 1.

[0019] Figure 2 The images shown are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the hair-based biomass carbon nanotubes prepared in Example 2.

[0020] Figure 3 This is a scanning electron microscope image of the hair-based biomass carbon nanotubes prepared in Example 3.

[0021] Figure 4 This is a scanning electron microscope image of the hair-based biomass carbon nanotubes prepared in Example 4.

[0022] Figure 5 The images are scanning electron microscope (SEM) images of the different materials prepared in Example 5, where (a) is carbon nanotubes prepared by the synergistic effect of KOH and H2O2, (b) is activated carbon prepared by adding only KOH, and (c) is amorphous carbon prepared by adding only H2O2.

[0023] Figure 6 The images are scanning electron microscope (SEM) images of the material prepared in Example 6; (a) is a low-magnification image (×1.00k), and (b) is a high-magnification image (×40.0k).

[0024] Figure 7 The following are electrochemical performance graphs of the hair-based biomass carbon nanotube electrode sheet prepared in Example 7, where (a) is the cyclic voltammetry curve of carbon nanotubes prepared with different KOH ratios, (b) is the cyclic voltammetry curve of carbon nanotubes at different scan rates with a 1:2 ratio, and (c) is the galvanostatic charge-discharge curve of carbon nanotubes at different current densities with a 1:2 ratio. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0026] Example 1 Yak hair was washed with ultrapure water and dried. 50 g of the dried yak hair was placed in a metal mesh. It was treated under a steam flash explosion pressure of 1.5 MPa for 150 s to obtain a carbonized product. After drying, the carbonized product was characterized by elemental analysis, and the results are as follows: Figure 1 As shown. From Figure 1 It can be seen that the carbonized products of yak hair contain 0.5% Fe element. These naturally occurring iron elements provide favorable conditions for the subsequent growth of carbon nanotubes.

[0027] Example 2 (1) Wash the yak hair with ultrapure water, dry it, and place 50 g of the dried yak hair in a metal mesh. Treat it for 150 s under a steam flash explosion pressure of 1.5 MPa to obtain carbonized products.

[0028] (2) Take 1 g of carbonization product and mix it with KOH at mass ratios of 1:2, 1:3, and 1:4 respectively. Add 300 μL of H2O2 (30%) and mix thoroughly. Under nitrogen protection (200 mL / min), heat the mixture to 600℃ at a rate of 5℃ / min, hold it at that temperature for 1 hour, and then cool it down. Remove the mixture when the temperature drops to about 100℃.

[0029] (3) Neutralize the residual KOH in the previous step with 5% hydrochloric acid until neutral, then wash with ultrapure water to remove residual ions, and dry to obtain hair-based biomass carbon nanotubes.

[0030] Figure 2The images show scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the hair-based biomass carbon nanotubes prepared in Example 2. SEM results show that the diameter of the prepared carbon nanotubes ranges from 26 nm to 113 nm. The highest number of carbon nanotubes was obtained when the ratio of biochar to KOH was 1:2; at a ratio of 1:3, the surface of the carbon nanotubes was not smooth; and at a ratio of 1:4, the size of the carbon nanotubes ranged from 26 to 70 nm, with longer lengths but lower yields. TEM results indicate that the carbon nanotubes prepared under different KOH ratios all possess a porous internal structure.

[0031] Example 3 (1) Wash the yak hair with ultrapure water, dry it, and place 50 g of the dried yak hair in a metal mesh. Treat it for 150 s under a steam flash explosion pressure of 1.5 MPa to obtain carbonized products.

[0032] (2) Take 1 g of carbonization product, mix the carbonization product with KOH at a mass ratio of 1:2, and add 300 μL, 600 μL and 900 μL of H2O2 (30%) respectively, and mix evenly. Under nitrogen protection (200 mL / min), heat to 600℃ at a rate of 5℃ / min, hold for 1 hour and then cool down. Take it out when the temperature drops to about 100℃.

[0033] (3) Neutralize the residual KOH in the previous step with 5% hydrochloric acid until neutral, then wash with ultrapure water to remove residual ions, and dry to obtain hair-based biomass carbon nanotubes.

[0034] Figure 3 The image shown is a scanning electron microscope (SEM) image of the hair-based biomass carbon nanotubes prepared in Example 3. The results show that the diameter of the prepared carbon nanotubes ranges from 13 nm to 136 nm. The number of carbon nanotubes decreases when the volume of H2O2 increases to 900 μL; the highest number of carbon nanotubes is obtained when the volume of H2O2 is 600 μL, meaning that 1 g of carbon material corresponds to 600 μL of H2O2.

[0035] Example 4 (1) Wash the yak hair with ultrapure water, dry it, and place 50 g of the dried yak hair in a metal mesh. Treat it for 150 s under a steam flash explosion pressure of 1.5 MPa to obtain carbonized products.

[0036] (2) Take 1 g of carbonization product, mix the carbonization product with KOH at a mass ratio of 1:2, add 300 μL H2O2 (30%), and mix well. Under nitrogen protection (200 mL / min), heat to 600℃, 650℃, 700℃ and 750℃ respectively at a rate of 5℃ / min, hold for 1 hour and then cool down. Take it out when the temperature drops to about 100℃.

[0037] (3) Neutralize the residual KOH in the previous step with 5% hydrochloric acid until neutral, then wash with ultrapure water to remove residual ions, and dry to obtain hair-based biomass carbon nanotubes.

[0038] Figure 4 The image shown is a scanning electron microscope (SEM) image of the hair-based biomass carbon nanotubes prepared in Example 4. The results show that the diameter of the prepared carbon nanotubes ranges from 20 nm to 147 nm, and the carbon nanotubes prepared at 600 °C have the highest number and a size range of 25–130 nm, indicating that the optimal reaction temperature is 600 °C.

[0039] Example 5 (1) Wash the yak hair with ultrapure water, dry it, and place 50 g of the dried yak hair in a metal mesh. Treat it for 150 s under a steam flash explosion pressure of 1.5 MPa to obtain carbonized products.

[0040] (2) Take 1 g of carbonization product and perform the following three treatments: ① Mix the carbonization product with KOH at a mass ratio of 1:2 and add 600 μL of H2O2 (30%); ② Mix only the carbonization product with KOH at a mass ratio of 1:2 without adding H2O2; ③ Add only 600 μL of H2O2 (30%) without adding KOH. After mixing evenly, under nitrogen protection (200 mL / min), heat to 600℃ at a rate of 5℃ / min, hold for 1 hour, then cool down. Take it out when the temperature drops to about 100℃.

[0041] (3) Neutralize the residual KOH in the previous step with 5% hydrochloric acid until neutral, then wash with ultrapure water to remove residual ions, and dry to obtain the corresponding material.

[0042] Figure 5 The image shown is a scanning electron microscope (SEM) image of the material prepared in Example 5. The results show that, under the synergistic effect of KOH and H₂O₂ ( Figure 5 a) Generate hair-based biomass carbon nanotubes; only add KOH ( Figure 5 b) Generate hair-based biomass activated carbon; add only H2O2 ( Figure 5 c) Formation of amorphous carbon. This indicates that the synergistic effect of KOH and H2O2 is key to the formation of carbon nanotubes.

[0043] Example 6 (1) Take 1 g of commercial activated carbon and mix it with KOH at a mass ratio of 1:2. Add 600 μL of H2O2 (30%) and mix well. Under nitrogen protection (200 mL / min), heat to 600℃ at a rate of 5℃ / min, keep warm for 1 hour and then cool down. Take it out when the temperature drops to about 100℃.

[0044] (2) Neutralize the residual KOH in the previous step with 5% hydrochloric acid until neutral, then wash with ultrapure water to remove residual ions, and dry to obtain the product.

[0045] Figure 6 The scanning electron microscope (SEM) results of the commercial activated carbon in Example 6 under the synergistic effect of KOH and H2O2 showed that the original commercial activated carbon exhibited a very loose structure, but no carbon nanotubes were formed, indicating that the method of the present invention is specific for hair-like biomass.

[0046] Example 7 (1) Take 3 mg of each of the yak hair-based carbon nanotubes prepared in the three different KOH ratios (1:2, 1:3, 1:4) in Example 2, mix them with the conductive agent (acetylene black) and binder (polytetrafluoroethylene) at a mass ratio of 8:1:1, grind them thoroughly, add an appropriate amount of anhydrous ethanol, and stir thoroughly to form a slurry. Coat the slurry evenly on the current collector (foamed nickel), with an effective coating area of ​​1 cm × 1 cm. Place it in an oven to dry, forming an electrode sheet.

[0047] (2) The performance of the electrode sheet was tested using a three-electrode system of an electrochemical workstation: the working electrode was the electrode sheet prepared above, the counter electrode was a platinum wire, the reference electrode was Hg / HgO, and the electrolyte was a 6 M KOH solution.

[0048] Figure 7 The figure shown is an electrochemical performance diagram of the hair-based biomass carbon nanotube electrode sheet prepared in Example 7. Figure 7 (a) Cyclic voltammetry curves of carbon nanotubes prepared with different KOH ratios. The results show that when the ratio of carbon material to KOH is 1:2, the curve area is the largest and the current response is the strongest, indicating that its specific capacitance is the highest. Figure 7 (b) Cyclic voltammetry curves of carbon nanotubes prepared at a ratio of 1:2 at different scan rates. The curves still maintain a good rectangular shape at a rate of 100 mV / s, indicating good rate performance. Figure 7 (c) shows the galvanostatic charge-discharge curves of carbon nanotubes prepared in a 1:2 ratio at different current densities. At a current density of 0.5 A / g, the specific capacitance is 225 F / g, the energy density is 31.25 Wh / kg, the power density is 250 W / kg, and the coulombic efficiency is close to 100%, indicating that the material has excellent electrochemical performance and is very suitable as an electrode material for supercapacitors.

Claims

1. A hair-based biomass carbon nanotube, characterized in that: The hair-based biomass carbon nanotubes have a diameter of 13~150 nm and have an internal porous structure. It is prepared by the following method: the hair raw material is cleaned and dried, and then subjected to steam flash explosion treatment to obtain hair-based biochar; the hair-based biochar is then mixed with potassium hydroxide and hydrogen peroxide, and reacted at 600℃~750℃ under inert gas protection, and then washed and dried to obtain the final product.

2. A method for preparing hair-based biomass carbon nanotubes, characterized in that, Includes the following steps: (1) Carbonization: The hair raw material is cleaned and dried, and then treated under steam flash explosion conditions to obtain hair-based biochar; (2) Preparation of carbon nanotubes: The hair-based biochar obtained in step (1) is mixed with potassium hydroxide and hydrogen peroxide, and heated to 600℃~750℃ under inert gas protection for heat preservation reaction, and then cooled down; (3) Washing: Wash the product obtained in step (2) until neutral, and dry it to obtain the hair-based biomass carbon nanotubes.

3. The preparation method according to claim 2, characterized in that: In step (1), the pressure of the steam flash explosion is 1.5 MPa and the processing time is 150 s.

4. The preparation method according to claim 2, characterized in that: In step (1), the hair is yak hair.

5. The preparation method according to claim 2, characterized in that: In step (2), the mass ratio of hair-based biochar to KOH is 1:2 to 1:

4.

6. The preparation method according to claim 2, characterized in that: In step (2), the concentration of hydrogen peroxide is 30%, and the amount used is 300 μL to 900 μL per 1 g of hair-based biochar.

7. The preparation method according to claim 2, characterized in that: In step (2), the heating rate is 5°C / min, and the holding time is 1 hour.

8. The preparation method according to claim 2, characterized in that: In step (3), 5% hydrochloric acid is used for neutralization and washing, and then ultrapure water is used for rinsing until neutral.

9. The application of the hair-based biomass carbon nanotubes of claim 1 or the hair-based biomass carbon nanotubes prepared by the preparation method of claim 2 in the preparation of supercapacitor electrode materials.

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