Phosphorus-activated chitosan-derived carbon composite gel, and preparation method and application thereof

Abstract

The application discloses phosphorus-activated chitosan derivative carbon composite gel and a preparation method and application thereof. The composite gel is a three-dimensional network structure formed by cross-linking of phosphorus-activated chitosan derivative carbon and polyvinyl alcohol / zinc chloride electrolyte; wherein the phosphorus-activated chitosan derivative carbon is formed by calcining chitosan and phytic acid in an inert gas atmosphere. The chitosan and the phytic acid are calcined at high temperature to obtain the phosphorus-activated chitosan derivative carbon; and then the phosphorus-activated chitosan derivative carbon is cross-linked with the polyvinyl alcohol / zinc chloride electrolyte to form the composite gel with the phosphorus-activated chitosan derivative carbon as a base material, the polyvinyl alcohol as a connecting medium and the zinc chloride as a conductive medium. The composite gel has excellent mechanical properties, electrochemical properties and sensing properties, and has a wide application prospect in the fields of supercapacitors and sensors.

Description

Technical Field

[0001] This invention belongs to the field of multifunctional composite material technology, specifically relating to a phosphorus-activated chitosan-derived carbon composite gel, its preparation method, and its application. Background Technology

[0002] With the rapid development of the global economy, energy and environmental issues have always been two unavoidable key problems. As a new type of high-efficiency energy storage device, the supercapacitor stores energy through a double-layer interface formed between electrodes and electrolyte. Compared to traditional capacitors, supercapacitors have larger capacity, specific energy, and energy density, a wider operating temperature range, and an extremely long service life; compared to batteries, they have higher specific power and are environmentally friendly. Sensors are devices that receive signals or stimuli and generate a response, converting a measured physical or chemical quantity into a corresponding output. They are the primary link in realizing automatic detection and automatic control. Sensors are characterized by low manufacturing cost, more accurate readings, and rapid response to changes.

[0003] Chitosan and its derivatives are natural, environmentally friendly, and economical biomaterials, while polyvinyl alcohol is a water-soluble polymer. Due to their respective characteristics, both have been widely used in the fields of supercapacitors and sensors, but they still face many challenges. For example, although carbonization can effectively improve the conductivity of chitosan and its derivatives, the flexibility, mechanical strength, and environmental adaptability of the materials are severely affected after carbonization. Polyvinyl alcohol is very sensitive to some substances (such as boric acid and dichromate), which can cause irreversible gelation.

[0004] Therefore, it is of great significance to explore a multifunctional composite material that can be used in both supercapacitors and sensors. Summary of the Invention

[0005] To address the aforementioned shortcomings, the present invention aims to provide a phosphorus-activated chitosan-derived carbon composite gel, its preparation method, and its application, thereby solving the problem that existing materials cannot be simultaneously applied to supercapacitors and sensors.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] On one hand, the present invention provides a phosphorus-activated chitosan-derived carbon composite gel, which is a three-dimensional network structure formed by crosslinking phosphorus-activated chitosan-derived carbon with polyvinyl alcohol / zinc chloride electrolyte; wherein, the phosphorus-activated chitosan-derived carbon is formed by calcining chitosan and phytic acid in an inert gas atmosphere.

[0008] Preferably, the mass ratio of phosphorus-activated chitosan-derived carbon to polyvinyl alcohol / zinc chloride electrolyte is (0.1~0.5):1.

[0009] Preferably, in the polyvinyl alcohol / zinc chloride electrolyte, the mass ratio of polyvinyl alcohol to zinc chloride is 1:(0.1~1). More preferably, it is 1:(0.2~1).

[0010] Preferably, the particle size of phosphorus-activated chitosan-derived carbon is ≤50μm.

[0011] Secondly, the present invention provides a method for preparing a phosphorus-activated chitosan-derived carbon composite gel, comprising the following steps:

[0012] Chitosan was dissolved in phytic acid solution to form a mixture, and the mixture was calcined in an inert gas atmosphere to obtain phosphorus-activated chitosan-derived carbon.

[0013] A polyvinyl alcohol solution and a zinc chloride solution are mechanically mixed at a first temperature to obtain a polyvinyl alcohol / zinc chloride electrolyte.

[0014] Phosphorus-activated chitosan-derived carbon was mechanically mixed with polyvinyl alcohol / zinc chloride electrolyte at a second temperature, followed by rapid freezing and salting out to obtain a phosphorus-activated chitosan-derived carbon composite gel.

[0015] In the above scheme, the polyvinyl alcohol / zinc chloride electrolyte has a large three-dimensional network structure formed by the cross-linking of polyvinyl alcohol and zinc chloride, and there are many nodes in the three-dimensional network, which is conducive to further cross-linking with phosphorus-activated chitosan-derived carbon to form a more stable composite structure.

[0016] Preferably, the phytic acid solution has a mass percentage concentration of 0.01~0.1%, and the mass ratio of chitosan to phytic acid solution is 1:(0.05~0.2).

[0017] Preferably, the calcination temperature is 600~1000℃ and the calcination time is 8~12h.

[0018] Preferably, the method for mechanically mixing a polyvinyl alcohol solution and a zinc chloride solution at a first temperature to obtain a polyvinyl alcohol / zinc chloride electrolyte includes: ultrasonically dispersing polyvinyl alcohol in water, then stirring at a first temperature to obtain a polyvinyl alcohol solution, and then adding a zinc chloride solution to the polyvinyl alcohol solution and stirring thoroughly.

[0019] Preferably, the ultrasonic dispersion time is 10-30 min, the stirring rate during the preparation of the polyvinyl alcohol solution is 800-1200 rpm, and the stirring time is 10-30 min.

[0020] Preferably, the stirring rate after adding the zinc chloride solution is 800~1200 rpm, and the stirring time is 10~30 min.

[0021] Preferably, the method for mechanically mixing phosphorus-activated chitosan-derived carbon and polyvinyl alcohol / zinc chloride electrolyte at the second temperature is stirring, with a stirring rate of 800~1200 rpm and a stirring time of 10~30 min.

[0022] Preferably, the mass percentage concentration of the polyvinyl alcohol solution is 5-20%, and the mass percentage concentration of the zinc chloride solution is 20-50%.

[0023] Preferably, both the first and second temperatures are 80~95℃.

[0024] Preferably, the quick-freezing process is as follows: quick-freezing at -30~-20℃ for 2~8 hours.

[0025] Preferably, the salting-out step is as follows: salting out in a salt solution with a mass fraction of 30-80% for 12-24 hours.

[0026] Preferably, the salt solution is at least one of sodium citrate solution, ammonium sulfate solution, and ammonium chloride solution.

[0027] Thirdly, the present invention provides an application of the phosphorus-activated chitosan-derived carbon composite gel described in the first aspect in a supercapacitor or sensor.

[0028] Preferably, when phosphorus-activated chitosan-derived carbon composite gel is applied to a supercapacitor, the specific application method is as follows: the phosphorus-activated chitosan-derived carbon composite gel is used as an electrode and, together with the electrolyte, is used to make a supercapacitor.

[0029] Preferably, when phosphorus-activated chitosan-derived carbon composite gel is applied to a sensor, the specific application method is as follows: the phosphorus-activated chitosan-derived carbon composite gel is directly used as a sensor, attached to the joint of the human body, and the electrical signal generated during human movement is captured by a multimeter.

[0030] The beneficial effects of this invention are:

[0031] This invention involves high-temperature calcination of chitosan and phytic acid to obtain phosphorus-activated chitosan-derived carbon; subsequently, it is crosslinked with polyvinyl alcohol / zinc chloride electrolyte to form a composite gel with phosphorus-activated chitosan-derived carbon as the base material, polyvinyl alcohol as the connecting medium, and zinc chloride as the conductive medium. This composite gel has excellent mechanical, electrochemical, and sensing properties, and has broad application prospects in the fields of supercapacitors and sensors.

[0032] The preparation method of this invention is simple, energy-efficient, and environmentally friendly. The resulting composite gel not only exhibits good charge-discharge cycle stability and large storage capacity, but also demonstrates excellent tensile properties and high sensitivity, making it suitable for both supercapacitors and sensors. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0034] Figure 1 This is a tensile stress-strain diagram of the phosphorus-activated chitosan-derived carbon composite gel in Example 1 of the present invention;

[0035] Figure 2 This is a compressive stress-strain diagram of the phosphorus-activated chitosan-derived carbon composite gel in Example 1 of the present invention;

[0036] Figure 3 The sensing performance of the phosphorus-activated chitosan-derived carbon composite gel in Example 1 of this invention on the bending of human fingers;

[0037] Figure 4 This is a graph showing the sensing performance of the phosphorus-activated chitosan-derived carbon composite gel in Example 1 of the present invention on the bending of the human wrist.

[0038] Figure 5 This is a graph showing the sensing performance of the phosphorus-activated chitosan-derived carbon composite gel in Example 1 of the present invention on the bending of the human elbow.

[0039] Figure 6 This is a graph showing the sensing performance of the phosphorus-activated chitosan-derived carbon composite gel in Example 1 of the present invention on human knee flexion. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] Example 1

[0042] A phosphorus-activated chitosan-derived carbon composite gel is prepared by the following method:

[0043] (1) Chitosan was dissolved in a phytic acid solution with a mass percentage concentration of 0.05%, wherein the mass ratio of chitosan to phytic acid solution was 1:0.1. After stirring thoroughly for 30 min, the solution was placed in a tube furnace with argon gas and calcined at 800℃ for 11 h. After cooling to room temperature, the solution was taken out and ground for 30 min to obtain phosphorus-activated chitosan-derived carbon with a particle size ≤50 μm.

[0044] (2) Add 5g of polyvinyl alcohol to 45mL of water and ultrasonically disperse for 30min. Under the conditions of 90℃ water bath, first stir at 1200rpm for 30min to obtain a polyvinyl alcohol solution with a mass fraction of 10%, then add a zinc chloride solution with a mass fraction of 20% to make the mass ratio of polyvinyl alcohol to zinc chloride 1:1. Stir at 1200rpm for 30min to obtain polyvinyl alcohol / zinc chloride electrolyte.

[0045] (3) Mix 1g of phosphorus-activated chitosan-derived carbon with 10g of polyvinyl alcohol / zinc chloride electrolyte in a 90℃ water bath at a speed of 1200rpm for 30min until the phosphorus-activated chitosan-derived carbon and polyvinyl alcohol / zinc chloride electrolyte are completely composited. Immediately pour the mixture into a prepared mold and freeze it at -30℃ for 6h. Then, soak it in a 50% sodium citrate solution for 24h to salt out the phosphorus-activated chitosan-derived carbon composite gel.

[0046] Example 2

[0047] A phosphorus-activated chitosan-derived carbon composite gel is prepared by the following method:

[0048] (1) Chitosan was dissolved in a phytic acid solution with a mass percentage concentration of 0.1% and the mass ratio of chitosan to phytic acid solution was 1:0.05. After stirring for 20 min, the solution was placed in a tube furnace with argon gas and calcined at 900℃ for 8 h. After cooling to room temperature, the solution was taken out and ground for 30 min to obtain phosphorus-activated chitosan-derived carbon with a particle size ≤50μm.

[0049] (2) Add 10g of polyvinyl alcohol to 40mL of water and ultrasonically disperse for 20min. Under the condition of 90℃ water bath, first stir at 1000rpm for 30min to obtain a polyvinyl alcohol solution with a mass fraction of 20%, then add a zinc chloride solution with a mass fraction of 30% to make the mass ratio of polyvinyl alcohol to zinc chloride 1:0.5. Stir at 1000rpm for 30min to obtain polyvinyl alcohol / zinc chloride electrolyte.

[0050] (3) Mix 2g of phosphorus-activated chitosan-derived carbon with 4g of polyvinyl alcohol / zinc chloride electrolyte in an 80°C water bath at a speed of 1200rpm for 30min until the phosphorus-activated chitosan-derived carbon and polyvinyl alcohol / zinc chloride electrolyte are completely composited. Immediately pour the mixture into a prepared mold and freeze it at -25°C for 4h. Then, soak it in a 70% ammonium sulfate solution for salting out for 16h to obtain phosphorus-activated chitosan-derived carbon composite gel.

[0051] Example 3

[0052] A phosphorus-activated chitosan-derived carbon composite gel is prepared by the following method:

[0053] (1) Chitosan was dissolved in a phytic acid solution with a mass percentage concentration of 0.01%, wherein the mass ratio of chitosan to phytic acid solution was 1:0.2. After stirring thoroughly for 30 min, the solution was placed in a tube furnace with argon gas and calcined at 700℃ for 10 h. After cooling to room temperature, the solution was taken out and ground for 20 min to obtain phosphorus-activated chitosan-derived carbon with a particle size ≤50 μm.

[0054] (2) Add 5g of polyvinyl alcohol to 45mL of water and ultrasonically disperse for 30min. Under the condition of 95℃ water bath, first stir at 900rpm for 20min to obtain a polyvinyl alcohol solution with a mass fraction of 10%, then add a zinc chloride solution with a mass fraction of 40% to make the mass ratio of polyvinyl alcohol to zinc chloride 1:0.4. Stir at 1200rpm for 30min to obtain polyvinyl alcohol / zinc chloride electrolyte.

[0055] (3) Mix 1g of phosphorus-activated chitosan-derived carbon with 5g of polyvinyl alcohol / zinc chloride electrolyte in a 95°C water bath at 1200 rpm for 30 min until the phosphorus-activated chitosan-derived carbon and polyvinyl alcohol / zinc chloride electrolyte are completely composited. Immediately pour the mixture into a prepared mold and freeze it at -20°C for 5 h. Then, soak it in a 60% ammonium chloride solution for 20 h to salt out the phosphorus-activated chitosan-derived carbon composite gel.

[0056] Example 4

[0057] The only difference from Example 1 is that in step (2), the mass ratio of polyvinyl alcohol to zinc chloride is 1:0.1.

[0058] Comparative Example 1

[0059] The only difference from Example 1 is that in step (1), the chitosan is insoluble in phytic acid solution, i.e., the chitosan is dissolved in water and calcined to obtain chitosan-derived carbon. Finally, a chitosan-derived carbon composite gel is prepared.

[0060] Comparative Example 2

[0061] The only difference from Example 1 is that the specific steps of step (3) are as follows: 10g of polyvinyl alcohol / zinc chloride electrolyte is loaded onto the surface of 1g of phosphorus-activated chitosan-derived carbon by drop coating. After 30min of treatment, all polyvinyl alcohol / zinc chloride electrolyte is fully loaded. Then, it is dried at 60°C to constant weight to obtain a phosphorus-activated chitosan-derived carbon composite gel loaded with polyvinyl alcohol / zinc chloride.

[0062] Comparative Example 3

[0063] The only difference from Example 1 is that salting out is not performed in step (3). Specifically, the mixture is first frozen at -30°C for 6 hours and then thawed at 30°C for 6 hours. This freeze-thaw cycle is repeated 6 times to obtain phosphorus-activated chitosan-derived carbon composite gel.

[0064] The tensile and compressive stresses of the composite gels obtained in Examples 1-4 and Comparative Examples 1-3 were tested respectively, and the results are shown in Table 1. Figure 1 and Figure 2 The tensile stress-strain diagram and compressive stress-strain diagram are respectively of the phosphorus-activated chitosan-derived carbon composite gel in Example 1.

[0065] Table 1

[0066]

[0067] As can be seen from Table 1, the phosphorus-activated chitosan-derived carbon composite gel prepared by this invention exhibits excellent comprehensive mechanical properties.

[0068] Application Example 1

[0069] The composite gels prepared in Examples 1-4 and Comparative Examples 1-3 were applied to supercapacitors. Specifically, the composite gels were connected to conductive copper strips, fixed onto glass slides to form electrode sheets, and a 1 mol / L sulfuric acid solution was used as the electrolyte to fabricate the supercapacitors. Electrochemical tests were performed on the seven resulting supercapacitors at a scan rate of 5 mV / s. The results are shown in Table 2.

[0070] Table 2

[0071]

[0072] The electrochemical test results in Table 2 show that, at a scan rate of 5 mV / s, the supercapacitor prepared using the phosphorus-activated chitosan-derived carbon composite gel obtained in the embodiments of the present invention exhibits a high specific capacitance. In Example 4, compared to Example 1, under the premise that all other conditions are equal, the amount of polyvinyl alcohol monomer affects the effective composite of phosphorus-activated chitosan-derived carbon in the composite gel structure, thus affecting the specific capacitance of the supercapacitor.

[0073] Application Example 2

[0074] The composite gels prepared in Examples 1-4 and Comparative Examples 1-3 were applied to sensors. Specifically, a composite gel with a length of 2cm, a width of 5cm, and a thickness of 2mm was directly used as a sensor and attached to a human joint. The electrical signals generated during human movement were captured by a multimeter.

[0075] The changes in electrical signals under four different human movement conditions—finger flexion, wrist flexion, elbow flexion, and knee flexion—were detected sequentially, and the results are shown in Table 3. Figures 3-6 The graphs show the changes in electrical signals of the phosphorus-activated chitosan-derived carbon composite gel obtained in Example 1 under four different human movement conditions.

[0076] Table 3

[0077]

[0078] As can be seen from Tables 1-3, the phosphorus-activated chitosan-derived carbon composite gel prepared by the method of the present invention exhibits good mechanical properties such as tensile and compressive properties; it can quickly respond to the current signal generated during human movement, and it can generate current signals with different characteristics for detecting the movement of different parts of the human body, showing excellent sensing performance; moreover, it exhibits good specific capacitance in supercapacitors, and can be used in both supercapacitor and sensor fields.

[0079] Compared with Example 1, Comparative Example 1 did not perform phosphorus activation on the chitosan-derived carbon, resulting in a chitosan-derived carbon composite gel with poor performance in supercapacitor and sensor applications.

[0080] Compared with Example 1, the phosphorus-activated chitosan-derived carbon composite gel prepared by the loading method in Comparative Example 2 could not achieve good performance in both supercapacitor and sensor applications.

[0081] Compared with Example 1, Comparative Example 3 shows that, under otherwise identical conditions, the phosphorus-activated chitosan-derived carbon composite gel without freeze-drying treatment exhibits poor mechanical properties. Furthermore, the resulting phosphorus-activated chitosan-derived carbon composite gel cannot simultaneously achieve good performance in both supercapacitor and sensor applications.

[0082] In summary, this invention uses zinc chloride as a conductive medium and accelerates charge transfer and energy transfer through the interaction between zinc chloride, polyvinyl alcohol, and phosphorus-activated chitosan-derived carbon, thereby improving the storage capacity of supercapacitor devices. Through the coordination between zinc ions and various oxygen-rich functional groups of polyvinyl alcohol, a stable three-dimensional network structure is formed, which can protect the composite material from oxidation to a certain extent and significantly improve the electrochemical performance of the resulting composite material. This invention prepares a composite gel by stirring and mixing phosphorus-activated chitosan-derived carbon with polyvinyl alcohol / zinc chloride. This gel exhibits good tensile properties and generates different characteristic current signals when detecting movement in different parts of the human body, demonstrating excellent sensing performance.

[0083] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0084] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A phosphorus-activated chitosan-derived carbon composite gel, characterized in that, The composite gel is a three-dimensional network structure formed by crosslinking phosphorus-activated chitosan-derived carbon with polyvinyl alcohol / zinc chloride electrolyte; wherein, the phosphorus-activated chitosan-derived carbon is formed by calcining chitosan and phytic acid in an inert gas atmosphere; The preparation method of the phosphorus-activated chitosan-derived carbon composite gel includes the following steps: Chitosan was dissolved in phytic acid solution to form a mixture, and the mixture was calcined in an inert gas atmosphere to obtain phosphorus-activated chitosan-derived carbon. A polyvinyl alcohol solution and a zinc chloride solution are mechanically mixed at a first temperature to obtain a polyvinyl alcohol / zinc chloride electrolyte. The phosphorus-activated chitosan-derived carbon was mechanically mixed with the polyvinyl alcohol / zinc chloride electrolyte at a second temperature, and then subjected to rapid freezing. After salting out, the phosphorus-activated chitosan-derived carbon composite gel was obtained. The phytic acid solution has a mass percentage concentration of 0.01~0.1%, and the mass ratio of chitosan to phytic acid solution is 1:(0.05~0.2). The calcination temperature is 600~1000℃, and the calcination time is 8~12h; The mass ratio of the phosphorus-activated chitosan-derived carbon to the polyvinyl alcohol / zinc chloride electrolyte is (0.1~0.5):1; In the polyvinyl alcohol / zinc chloride electrolyte, the mass ratio of polyvinyl alcohol to zinc chloride is 1:(0.4~1); The quick-freezing process is as follows: quick-freeze at -30~-20℃ for 2~8 hours; The salting-out step is as follows: salting out in a salt solution with a mass fraction of 30-80% for 12-24 hours.

2. The phosphorus-activated chitosan-derived carbon composite gel according to claim 1, characterized in that, The particle size of the phosphorus-activated chitosan-derived carbon is ≤50μm.

3. The method for preparing phosphorus-activated chitosan-derived carbon composite gel according to claim 1, characterized in that, The polyvinyl alcohol solution has a mass percentage concentration of 5-20%, and the zinc chloride solution has a mass percentage concentration of 20-50%.

4. The method for preparing phosphorus-activated chitosan-derived carbon composite gel according to claim 1, characterized in that, Both the first temperature and the second temperature are 80~95℃.

5. The application of the phosphorus-activated chitosan-derived carbon composite gel according to any one of claims 1 to 2 in supercapacitors or sensors.

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