Preparation method and application of carbonized enteromorpha-mxene nanoflower composite sensing material dispersion

Abstract

The application designs a new method for preparing carbonized Enteromorpha-MXene nanoflower composite sensing material dispersion. The single-layer MXene nanosheet is obtained by etching and peeling the precursor MAX phase powder of MXene. In addition, the marine pollutant Enteromorpha is recycled and treated by soaking in an alkaline environment and high-temperature carbonization to obtain an electrode modification material. Then, by controlling the doping ratio of MXene nanosheet and carbonized Enteromorpha and the ultrasonic compounding time, the Enteromorpha-MXene nanoflower composite sensing material dispersion is synthesized. The morphology and performance of the synthesized material are characterized by SEM and cyclic voltammetry scanning characterization means. Due to the nanoflower structure of MXene, the surface area of the material is improved, so that the electrode modified by the carbonized Enteromorpha-MXene nanoflower composite material has a significant improvement in the electrical signal of the electrochemical sensor. The application also has certain application effect on other types of electrochemical sensors.

Description

Technical Field

[0001] This invention belongs to the field of two-dimensional material preparation technology, specifically relating to a method for preparing and applying a dispersion of carbonized seaweed-MXene nanoflower composite sensing material. Background Technology

[0002] Transition metal carbides or nitrides (MXenes), as novel two-dimensional layered materials, possess rich chemical properties, hydrophilic surfaces, and mechanical ceramic properties, and are widely used in photocatalysis, electrocatalysis, sensors, supercapacitors, lithium-ion batteries, and biomedicine. The high biocompatibility and stability of MXenes themselves enable them to produce complementary and synergistic effects when combined with other nanomaterials, effectively improving the sensitivity and selectivity of electrochemical sensors.

[0003] As a type of marine pollution waste, *Ulva prolifera* (seaweed) places enormous pressure on environmental governance every year. Given the shortage of industrial materials, appropriate measures can transform this waste into a valuable resource, which is highly beneficial. Furthermore, high-temperature carbonized *Ulva prolifera* can be used as a conductive material to improve the performance of electrochemical sensors, opening up possibilities for the exploration of novel electrochemical sensors.

[0004] By ultrasonically combining carbonized Ulva prolifera with MXene nanosheets peeled into monolayers, a carbonized Ulva prolifera film surrounded by MXene nanoflowers can be obtained. Characterization with an electrochemical characterization solution shows that the dispersion of this carbonized Ulva prolifera-MXene nanoflower composite sensing material can effectively improve the performance of electrochemical sensors, providing a new direction for the development of novel electrochemical sensors. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a dispersion of carbonized seaweed-MXene nanoflower composite sensing material and its application, thereby improving the response signal of electrochemical sensors during the detection process.

[0006] The technical solution of the present invention includes the following steps:

[0007] (1) Wash the seaweed with 0.2~0.6 M sodium dihydrogen phosphate and deionized water alternately until it is colorless, then soak it in an alkaline solution with a concentration of 4~8 M for 12~48 hours, dry it, and carbonize it by high temperature to obtain carbonized seaweed;

[0008] (2) Disperse the MAX phase powder in a strong acid and stir for 12-48 hours. Centrifuge to separate the precipitate and wash until the pH of the supernatant is 5-7. Redisperse the washed precipitate in water, sonicate for 70-90 minutes under a protective atmosphere, centrifuge to separate the upper suspension, which is the dispersion containing monolayer MXene.

[0009] (3) Grind and disperse the carbonized seaweed in water, mix it with a dispersion containing monolayer MXene, and sonicate for 6-12 hours to obtain a dispersion of carbonized seaweed-MXene nanoflower composite sensing material.

[0010] Preferably, in step (1), the alkaline solution is potassium hydroxide or sodium hydroxide; the high-temperature firing temperature is 600~1000℃, and the firing time is 0.5~1.5 h;

[0011] Preferably, in step (2), the MAX phase powder is one of Ti3AlC2 powder, Nb4AlC3 powder, Ta4AlC3 powder, or V4AlC3 powder, the strong acid is a mixed solution of HCl and LiF, the mass ratio of MAX phase powder to LiF to HCl is 1~3:3:20, and the protective gas is nitrogen or argon.

[0012] Preferably, in step (3), the concentration of the carbonized seaweed dispersion is 0.5~2.0 mg / ml, and the volume ratio of the carbonized seaweed dispersion to the dispersion containing monolayer MXene is 1:1~4.

[0013] The application of the carbonized seaweed-MXene nanoflower composite sensing material dispersion described in this invention is to apply the carbonized seaweed-MXene nanoflower composite sensing material dispersion to an electrochemical sensor.

[0014] The beneficial effects of this invention are as follows:

[0015] 1. The carbonized seaweed-MXene nanoflower composite sensing material dispersion prepared by the method of this invention provides a novel solution for the treatment of seaweed pollutants.

[0016] 2. The carbonized seaweed-MXene nanocomposite sensing material prepared by the method of the present invention has a flower-like thin film structure with a large specific surface area, which can provide more interfaces for electron exchange and provide better electrochemical sensing performance for the electrode.

[0017] 3. The MXene prepared by the method of the present invention is composed of two-dimensional transition metals titanium and carbon, with a large effective surface area. When combined with carbonized seaweed, it can effectively improve the electrochemical sensor performance of carbon ion liquid electrode (CILE).

[0018] 4. In summary, the carbonized *Ulva prolifera*-MXene nanoflower composite sensing material dispersion prepared by the method of this invention shows significant performance in electrochemical sensor applications. In characterization solutions of 0.1 mmol / L potassium ferricyanide and 1.0 mol / L KCl, the current increased by 9.78 μA to 10.38 μA. Attached Figure Description

[0019] Figure 1The image shows a scanning electron microscope (SEM) image of the MXene monolayer nanosheets prepared in Example 1.

[0020] Figure 2 The image shows a scanning electron microscope (SEM) image of the carbonized *Ulva prolifera* prepared in Example 1.

[0021] Figure 3 The image shows a scanning electron microscope (SEM) image of the carbonized Ulva prolifera-MXene nanoflower composite sensing material prepared in Example 1.

[0022] Figure 4 Cyclic voltammetry curves of the bare perfluorosulfonic acid membrane (Nafion) / CILE electrode and the Nafion / carbonized seaweed-MXene / CILE modified electrode prepared in Example 1 in a mixed electrolyte of 0.1 mmol / L K3[Fe(CN)6] and 1.0 mol / L KCl. Detailed Implementation

[0023] The present invention will be further described below with reference to embodiments and accompanying drawings, but the scope of protection of the present invention is not limited thereto. Example 1

[0024] (1) Wash the seaweed with 0.4M sodium dihydrogen phosphate (NaH2PO2) and deionized water alternately until it is colorless, then soak it in 6M potassium hydroxide (KOH) for 24 hours, dry it, and then carbonize the dried seaweed at 800℃ for 1 hour to obtain carbonized seaweed.

[0025] (2) First, slowly add 15g LiF to a plastic beaker containing 100ml of 9M HCl solution and stir for 10min until completely dissolved. Then, slowly add 10g Ti3AlC2 powder over 5min and stir for 24h. Centrifuge and wash the precipitate with water until the pH of the supernatant is about 6. Redisperse the washed precipitate in water, sonicate for 80min under nitrogen protection, centrifuge, and take the upper suspension, which is the Ti3C2T containing monolayer. x The dispersion;

[0026] (3) The carbonized *Ulva prolifera* was ground and dispersed in water to obtain a 1.0 mg / ml dispersion of carbonized *Ulva prolifera*, which was then mixed with a solution containing monolayer Ti3C2T. x The dispersion was mixed with carbonized Ulva prolifera dispersion and containing monolayer Ti3C2T x The dispersion was prepared by volume ratio of 1:2 and sonication for 9 hours to obtain carbonized *Ulva prolifera*-Ti3C2T. x Dispersion of nanoflower composite sensing material.

[0027] The carbonized *Ulva prolifera*-Ti3C2T obtained in this embodiment xA dispersion of nanoflower composite sensing material was drop-coated onto the surface of CILE to obtain carbonized *Ulva prolifera*-Ti3C2T. x / CILE modified electrode, after drying, Nafion solution was added dropwise to its surface to obtain Nafion / carbonized Ulva prolifera-Ti3C2T x A Nafion / CILE modified electrode was prepared using the same method as a control. The electrochemical performance of the Nafion / CILE electrode was tested by cyclic voltammetry. I p The current was 38.78 μA, Nafion / Carbonized Ulva prolifera-Ti3C2T x / CILE modified electrode I p The current was 49.16 μA, an increase of 10.38 μA. Example 2

[0028] (1) Wash the seaweed with 0.2M NaH2PO2 and deionized water alternately until it is colorless, then soak it in 4M sodium hydroxide (NaOH) for 12 hours, dry it, and then carbonize the dried seaweed at 600℃ for 0.5 hours to obtain carbonized seaweed.

[0029] (2) First, slowly add 6g LiF to a plastic beaker containing 40ml of 9M HCl solution and stir for 10min until completely dissolved. Then, slowly add 2g Nb4AlC3 powder over 5min and stir for 12h. Centrifuge and wash the precipitate with water until the pH of the supernatant is about 5. Redisperse the washed precipitate in water, sonicate for 70min under argon protection, centrifuge, and take the upper suspension, which is the Nb4AlC3 monolayer T. x The dispersion;

[0030] (3) The carbonized seaweed was ground and dispersed in water to obtain a 0.5 mg / ml carbonized seaweed dispersion, which was then mixed with a monolayer of Nb4C3T. x The dispersion was mixed with carbonized Ulva prolifera dispersion and contained monolayer Nb4C3T x The dispersion was prepared by volume ratio of 1:1 and sonication for 6 hours to obtain carbonized *Ulva prolifera*-Nb4C3T. x Dispersion of nanoflower composite sensing material.

[0031] The carbonized *Ulva prolifera*-Nb4C3T obtained in this embodiment x A dispersion of nanoflower composite sensing material was drop-coated onto the surface of CILE to obtain carbonized *Ulva prolifera*-Nb4C3T. x / CILE modified electrode, after drying, Nafion solution was added dropwise to its surface to obtain Nafion / carbonized Ulva prolifera-Nb4C3T xA Nafion / CILE modified electrode was prepared using the same method as a control. The electrochemical performance of the Nafion / CILE electrode was tested by cyclic voltammetry. I p The current was 39.52 μA, Nafion / carbonized seaweed-Nb4C3T x / CILE modified electrode I p The current was 49.30μA, an increase of 9.78μA. Example 3

[0032] (1) Wash the seaweed with 0.5M NaH2PO2 and deionized water alternately until it is colorless, then soak it in 7M NaOH for 48 hours, dry it, and then carbonize the dried seaweed at 900℃ for 1.5 hours to obtain carbonized seaweed.

[0033] (2) First, slowly add 15g LiF to a plastic beaker containing 100ml of 9M HCl solution and stir for 10min until completely dissolved. Then, slowly add 10g Ta4AlC3 powder over 5min and stir for 36h. Centrifuge and wash the precipitate with water until the pH of the supernatant is about 6. Redisperse the washed precipitate in water, sonicate for 90min under nitrogen protection, centrifuge, and take the upper suspension, which is the monolayer of Ta4C3T. x The dispersion;

[0034] (3) The carbonized seaweed was ground and dispersed in water to obtain a 1.5 mg / ml carbonized seaweed dispersion, which was then mixed with a monolayer of Ta4C3T. x The dispersion was mixed with carbonized Ulva prolifera dispersion and contained monolayer Ta4C3T x The dispersion was prepared by volume ratio of 1:3 and sonication for 10 hours to obtain carbonized *Ulva prolifera*-Ta4C3T. x Dispersion of nanoflower composite sensing material.

[0035] The carbonized seaweed-Ta4C3T obtained in this embodiment x A dispersion of nanoflower composite sensing material was drop-coated onto the surface of CILE to obtain carbonized Ulva prolifera-Ta4C3T. x / CILE modified electrode, after drying, Nafion solution was added dropwise to its surface to obtain Nafion / carbonized Ulva prolifera-Ta4C3T x A Nafion / CILE modified electrode was prepared using the same method as a control. The electrochemical performance of the Nafion / CILE electrode was tested by cyclic voltammetry. I pThe current was 38.12 μA, Nafion / carbonized seaweed-Ta4C3T x / CILE modified electrode I p The current was 48.01μA, an increase of 9.89μA. Example 4

[0036] (1) Wash the seaweed with 0.6M NaH2PO2 and deionized water alternately until it is colorless, then soak it in 8M KOH for 24 hours, dry it, and then carbonize the dried seaweed at 1000℃ for 1 hour to obtain carbonized seaweed.

[0037] (2) First, slowly add 6g LiF to a plastic beaker containing 40ml of 9M HCl solution and stir for 10min until completely dissolved. Then, slowly add 6g V4AlC3 powder over 5min and stir for 48h. Centrifuge and wash the precipitate with water until the pH of the supernatant is about 7. Redisperse the washed precipitate in water, sonicate for 80min under argon protection, centrifuge, and take the upper suspension, which is the precipitate containing monolayer V4C3T. x The dispersion;

[0038] (3) The carbonized seaweed was ground and dispersed in water to obtain a 2.0 mg / ml carbonized seaweed dispersion, which was then mixed with a monolayer of V4C3T. x The dispersion was mixed with carbonized Ulva prolifera dispersion and contained monolayer V4C3T x The dispersion was prepared by volume ratio of 1:4 and sonication for 12 hours to obtain carbonized Ulva prolifera-V4C3T. x Dispersion of nanoflower composite sensing material.

[0039] The carbonized seaweed-V4C3T obtained in this embodiment x A dispersion of nanoflower composite sensing material was drop-coated onto the surface of CILE to obtain carbonized Ulva prolifera-V4C3T. x / CILE modified electrode, after drying, Nafion solution was added dropwise to its surface to obtain Nafion / carbonized Ulva prolifera-V4C3T x A Nafion / CILE modified electrode was prepared using the same method as a control. The electrochemical performance of the Nafion / CILE electrode was tested by cyclic voltammetry. I p The current was 37.44 μA, Nafion / Carbonized Ulva prolifera-V4C3T x / CILE modified electrode I p The current was 47.59 μA, an increase of 10.15 μA.

[0040]

[0041] Figure 1 The scanning electron microscope image shows the MXene monolayer nanosheets with a scale bar of 1 μm prepared in Example 1. As can be seen from the image, MXene with uniform morphology and monolayer sheet structure has been successfully obtained.

[0042] Figure 2 Scanning electron microscopy characterization of the carbonized Ulva prolifera prepared in Example 1 with a scale bar of 100 nm; it can be seen that the carbonized Ulva prolifera has a porous film-like structure.

[0043] Figure 3 Scanning electron microscopy characterization of the *Ulva prolifera*-MXene nanoflower composite material prepared in Example 1. Figure 3 In the image, A represents a scanning electron microscope (SEM) image of the carbonized *Ulva prolifera*-MXene nanoflower composite material with a scale bar of 1 μm. Figure 3 B in the image is a scanning electron microscope (SEM) image of the carbonized *Ulva prolifera*-MXene nanoflower composite material at a scale bar of 100 nm. The image shows that the thin film structure of the carbonized *Ulva prolifera* remains. After ultrasonication, the MXene nanosheets are aggregated into individual nanoflowers of uniform size, which adhere to the surface of the carbonized *Ulva prolifera* film, forming the carbonized *Ulva prolifera*-MXene nanoflower composite sensing material.

[0044] Figure 4 Cyclic voltammetry curves of the Nafion / CILE bare electrode and the Nafion / carbonized Ulva prolifera-MXene / CILE modified electrode prepared in Example 1 in a mixed electrolyte of 0.1 mmol / L K3[Fe(CN)6] and 1.0 mol / L KCl. It can be seen that the CILE electrode modified with the carbonized Ulva prolifera-MXene nanoflower composite material dispersion shows a significant increase in electrical signal, while the Nafion / CILE electrode shows a significantly increased signal. I p The current was 38.78 μA, while the electrode modified with the carbonized *Ulva prolifera*-MXene nanoflower composite material dispersion... I p The current was 49.16 μA, showing a significant increase. This indicates that the carbonized *Ulva prolifera*-MXene nanoflower composite material dispersion has a significant effect on enhancing the electrochemical signal and improving the performance of the electrochemical sensor.

[0045] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. The application of a carbonized *Ulva prolifera*-MXene nanoflower composite sensing material dispersion, characterized in that, The carbonized *Ulva prolifera*-MXene nanoflower composite sensing material dispersion is applied to an electrochemical sensor. The preparation method of the carbonized *Ulva prolifera*-MXene nanoflower composite sensing material dispersion includes the following steps: (1) Wash the seaweed with 0.2~0.6 M sodium dihydrogen phosphate and deionized water alternately until it is colorless, then soak it in an alkaline solution with a concentration of 4~8 M for 12~48 hours, dry it, and carbonize it by high temperature to obtain carbonized seaweed; (2) Disperse the MAX phase powder in a strong acid and stir for 12-48 hours. Centrifuge to separate the precipitate and wash until the pH of the supernatant is 5-7. Redisperse the washed precipitate in water, sonicate for 70-90 minutes under a protective atmosphere, centrifuge to separate the upper suspension, which is the dispersion containing monolayer MXene. (3) Grind and disperse the carbonized seaweed in water, mix it with a dispersion containing monolayer MXene, and sonicate for 6-12 hours to obtain a dispersion of carbonized seaweed-MXene nanoflower composite sensing material. In step (2), the MAX phase powder is one of Ti3AlC2 powder, Nb4AlC3 powder, Ta4AlC3 powder, or V4AlC3 powder, the strong acid is a mixed solution of HCl and LiF, the mass ratio of MAX phase powder to LiF to HCl is 1~3:3:20, and the protective gas is nitrogen or argon. The carbonized seaweed-MXene nanoflower composite sensing material has a flower-like thin film structure.

2. The application of the carbonized *Ulva prolifera*-MXene nanoflower composite sensing material dispersion according to claim 1, characterized in that, In step (1), the alkaline solution is potassium hydroxide or sodium hydroxide, the high-temperature firing temperature is 600~1000℃, and the firing time is 0.5~1.5 h.

3. The application of the carbonized *Ulva prolifera*-MXene nanoflower composite sensing material dispersion according to claim 1, characterized in that, In step (3), the concentration of the carbonized seaweed dispersion is 0.5~2.0 mg / ml, and the volume ratio of the carbonized seaweed dispersion to the dispersion containing monolayer MXene is 1:1~4.

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