A MXene quantum dot tip heterojunction material with high light-to-heat conversion efficiency and its preparation method

Abstract

The present invention discloses a MXene quantum dot tip heterojunction material with high light-to-heat conversion efficiency, comprising a substrate and a Co3O4 nanoneedle array structure grown in situ on the substrate; the surface of the Co3O4 nanoneedles is loaded with Ti3C2MXene quantum dots, which are fixed to the surface of the Co3O4 nanoneedles through heterogeneous charge interaction forces. The present invention also discloses a method for preparing the above-mentioned MXene quantum dot tip heterojunction material, comprising the following steps: (1) preparing an array of Co3O4 nanoneedle structures on a substrate using a hydrothermal method; and (2) soaking the product of step (1) in a MXene quantum dot solution under ultraviolet light for 6 to 8 hours.

Description

Technical Field

[0001] The present invention relates to a MXene quantum dot tip heterojunction material with high light-to-heat conversion efficiency, and also relates to a method for preparing the material. Background Art

[0002] Photothermal conversion technology converts absorbed light energy into thermal energy, playing an important role in solar energy utilization, photothermal therapy, and thermal catalysis. Within this field, two-dimensional transition metal carbides, nitrides, or carbonitrides (MXenes) have attracted significant attention due to their unique photothermal conversion properties. MXene nanosheets, due to their efficient light absorption, can absorb light energy across a wide spectral range (from the ultraviolet to the near-infrared) and efficiently convert it into thermal energy. Their two-dimensional structure enables photons to reflect multiple times within the nanosheets, improving light absorption efficiency. Compared to MXene nanosheets, MXene quantum dots (MDQs) can further enhance the material's photothermal conversion performance. While the narrow bandgap of MXene quantum dots enhances light absorption, it also easily triggers rapid recombination of photogenerated electron-hole pairs, shortening their lifetime, reducing photothermal conversion efficiency, and making it difficult to maintain high temperatures, particularly under low light intensity conditions or when a sustained thermal effect is required. Summary of the Invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a MXene quantum dot tip heterojunction material with high photothermal conversion efficiency. In this material, Co3O4 nanoneedles and Ti3C2MXene quantum dots form a tip heterojunction structure, and an efficient electron-hole separation interface can be formed at the contact interface between the two, thereby effectively reducing the recombination of photogenerated carriers and improving the photothermal conversion efficiency. Another purpose of the present invention is to provide a preparation method of the above-mentioned Ti3C2MXene quantum dot tip heterojunction material.

[0004] Technical solution: The MXene quantum dot tip heterojunction material with high photothermal conversion efficiency described in the present invention includes a substrate and a Co3O4 nanoneedle array structure grown in situ on the substrate; Ti3C2MXene quantum dots are laid on the surface of the Co3O4 nanoneedles, and the Ti3C2MXene quantum dots are fixed on the surface of the Co3O4 nanoneedles through the interaction force of heterogeneous charges, and the two form a tip heterojunction structure.

[0005] The material of the present invention has an array-type tip heterojunction structure. On the one hand, the tip structure of the material can significantly enhance the local light field and concentrate light energy through the "hotspot" effect, thereby improving the light absorption efficiency; on the other hand, the array-type tip heterojunction structure can cause the incident light to undergo multiple local reflections and scattering in these areas, thereby increasing the residence time and absorption depth of the light; in addition, the tip morphology can also induce a local plasma resonance effect, further enhancing the interaction efficiency between photons and materials, and significantly improving the photothermal conversion performance of the material.

[0006] The substrate is one of foam nickel, foam copper, carbon cloth or carbon paper; and the tip carrier Co3O4 nanoneedles are in-situ grown on the substrate.

[0007] Among them, the mass of Ti3C2MXene quantum dots loaded on the tip carrier Co3O4 nanoneedles is 1 to 10 mg.

[0008] The preparation method of the above material comprises the following steps:

[0009] (1) Co3O4 nanoneedle structures arranged in an array are prepared on a substrate using a hydrothermal method;

[0010] (2) Under irradiation with an ultraviolet lamp of a wavelength of 360 nm, the product of step (1) is placed in a Ti3C2MXene quantum dot solution and soaked for 6 to 8 hours to obtain a Ti3C2MXene quantum dot tip heterojunction material in which MXene quantum dots are loaded on Co3O4 nanoneedles.

[0011] Wherein, in step (1), the temperature of the hydrothermal reaction is 100-120° C., and the hydrothermal time is 6-12 h.

[0012] Among them, a Co3O4 nanoneedle structure arranged in an array is prepared on a nickel foam substrate with a thickness of 1 mm. The specific process is as follows: 0.1-0.2g Co(NO3)2·6H2O, 0.3-0.5g NH4F and 2-3g urea are dissolved in 20-30mL deionized water and stirred to obtain a reaction solution; the nickel foam is placed in 3M HCl to remove surface oxides, and then rinsed with deionized water three times and placed in the reaction solution, and hydrothermaled at 100-120°C for 10-20h; after the hydrothermal reaction is completed, the initial product Co(OH)F is obtained; the initial product is first rinsed with deionized water, then blown dry with nitrogen, and finally calcined in air at 400-500°C for 3-4h to obtain a Co3O4 nanoneedle structure grown in situ on the substrate and arranged in an array.

[0013] Wherein, in step (2), the preparation process of MXene quantum dot solution is as follows: 1-1.2g Ti3AlC2, 12-15mL9M HCl and 1.6-2g LiF are mixed and etched at 40°C for 24-30h; after etching, a few-layer MXene solution is prepared by repeated centrifugal washing and ultrasonic crushing; the pH of the MXene solution is adjusted to 9-10 with ammonia water, and then hydrothermal treatment is performed at 100-120°C for 10-12h; after the hydrothermal treatment, the supernatant is taken and filtered through a 0.2μm pore size filter membrane to obtain a Ti3C2MXene quantum dot solution. Under irradiation with a wavelength of 360nm ultraviolet light, the product of step (1) is placed in the Ti3C2MXene quantum dot solution and soaked for 6-8h.

[0014] Among them, the average particle size of Ti3C2 MXene quantum dots is 1 to 2 nm.

[0015] Wherein, in step (2), the irradiation intensity of the ultraviolet lamp is 5-6W m -2 .

[0016] Wherein, in step (2), in the Ti3C2MXene quantum dot tip heterojunction material, the mass of the Ti3C2MXene quantum dots loaded on the tip carrier Co3O4 nanoneedles is 1 to 10 mg.

[0017] The present invention uses Co3O4 nanoneedles as the base semiconductor, and after uniformly mixing with negatively charged MXene quantum dots, forms a cutting-edge heterojunction under ultraviolet light irradiation, achieving a significant improvement in photothermal conversion performance. Combining Ti3C2MXene quantum dots with Co3O4 nanoneedles to form a cutting-edge heterojunction material helps to build an efficient electron-hole separation interface, reduce the recombination of photogenerated carriers, and improve photothermal conversion efficiency. The heterojunction of Ti3C2MXene quantum dots and Co3O4 nanoneedles also exhibits high infrared emissivity and effectively dissipates heat through infrared radiation. Therefore, in addition to its outstanding performance in photothermal applications, the cutting-edge heterojunction structure of the present invention also has important potential in the field of infrared false targets. Its efficient photothermal conversion and rapid response capabilities can quickly generate strong infrared radiation, simulate the infrared characteristics of real targets, and effectively protect real targets.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The material of the present invention tightly couples Ti3C2MXene quantum dots with two-dimensional structured Co3O4 nanoneedles, which can construct an efficient electron-hole separation interface, thereby reducing the recombination of photogenerated carriers and thus improving the photothermal conversion efficiency; (2) The Ti3C2MXene quantum dot tip heterojunction material of the present invention can effectively reduce the photothermal conversion efficiency under the influence of infrared light (200mW cm -2) Within 5 minutes of irradiation, the surface temperature quickly reached 93.9°C, significantly improving the photothermal conversion performance of MXene quantum dots. (3) The Ti3C2MXene quantum dot tip heterojunction material of the present invention has a full-band infrared emissivity of not less than 0.85 at room temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The transmission electron microscopy image and particle size distribution of MXene quantum dots in Example 1 are shown;

[0020] Figure 2 This is a scanning electron microscope image of the heterojunction between Co3O4 nanoneedles and MXene tips in Example 1;

[0021] Figure 3 This is a physical picture of the MXene quantum dot tip heterojunction material in Example 1;

[0022] Figure 4 This is a transmission electron microscopy image of the tip heterojunction of Co3O4 nanoneedles and MXene quantum dots in Example 1;

[0023] Figure 5 This is the photothermal response diagram of the MXene quantum dot tip heterojunction in Example 1;

[0024] Figure 6 is the infrared emissivity of the MXene quantum dot tip heterojunction in Example 1. DETAILED DESCRIPTION

[0025] Example 1

[0026] The method for preparing a MXene quantum dot tip heterojunction material with high light-to-heat conversion efficiency of the present invention comprises the following steps:

[0027] (1) 0.1 g of Co(NO3)2·6H2O, 0.3 g of NH4F, and 2 g of urea were dissolved in 20 mL of deionized water, stirred for 30 min to obtain a reaction solution, and the reaction solution was transferred to a 50 mL reactor; nickel foam treated with 3 M HCl (the purpose of the treatment was to remove oxides on the surface of the nickel foam) was placed in the reaction solution and hydrothermally heated at 120 ° C for 10 h; after the hydrothermal reaction was completed, the nickel foam was taken out, rinsed with deionized water 5 to 10 times, and blown dry with nitrogen to obtain the initial product Co(OH)F on the nickel foam; finally, the nickel foam was calcined in air at 400 to 500 ° C for 3 to 4 h to obtain a Co3O4 nanoneedle structure in situ grown on the nickel foam substrate and arranged in an array;

[0028] (2) Weigh 1 g of Ti3AlC2 raw material and place it in a 50 mL reactor. Add 12 mL of 9 M HCl and 1.6 g of LiF, and etch at 40 ° C for 30 h. After etching, centrifuge and wash the solution at 3500 rpm for multiple times until the pH of the supernatant is neutral. After the last centrifugation, ultrasonicate the aqueous solution in a N2 atmosphere for 3 h. After the ultrasonication, adjust the pH of the solution to 9-10 with ammonia water and hydrothermally heat it at 120 ° C for 12 h. After the hydrothermal reaction, take the supernatant and filter it through a 0.2 μm pore size filter membrane to obtain a MXene quantum dot solution.

[0029] (3) The Co3O4 nanoneedles prepared in step (1) were irradiated with a UV lamp with a wavelength of 360 nm (the irradiation intensity of the UV lamp was 5 W m -2 ) is placed in the MXene quantum dot solution (concentration of 0.2×10 -3 wt%) and immersed in the solution for 8 h to obtain a MXene quantum dot tip heterojunction material, which was recorded as MXeneQDs1@Co3O4; in the material, the mass of the MXene quantum dots loaded on the Co3O4 nanoneedles was 1 mg.

[0030] Example 2

[0031] The method for preparing a MXene quantum dot tip heterojunction material with high light-to-heat conversion efficiency of the present invention comprises the following steps:

[0032] (1) 0.2 g of Co(NO3)2·6H2O, 0.5 g of NH4F and 3 g of urea were dissolved in 30 mL of deionized water, stirred for 30 min to obtain a reaction solution, and the reaction solution was transferred to a 50 mL reactor; the nickel foam from which the surface oxides were removed by 3 M HCl was placed in the reaction solution and hydrothermaled at 120 ° C for 10 h; after the hydrothermal reaction was completed, the nickel foam was taken out, rinsed with deionized water 5 to 10 times, and blown dry with nitrogen to obtain the initial product Co(OH)F; finally, the nickel foam was calcined in air at 400 to 500 ° C for 3 to 4 h to obtain a Co3O4 nanoneedle structure in situ grown on the nickel foam substrate and arranged in an array;

[0033] (2) Weigh 1 g of Ti3AlC2 raw material and place it in a 50 mL reactor, add 12 mL of 9 M HCl and 1.6 g of LiF, and etch at 40 ° C for 30 h; after etching, centrifuge and wash several times at 3500 rpm until the pH of the supernatant is neutral; after the last washing centrifugation, ultrasonicate the aqueous solution under N2 atmosphere for 3 h; after the ultrasonication, adjust the pH of the solution to 9-10 with ammonia water, and hydrothermally heat at 120 ° C for 10 h; after the hydrothermal reaction, take the supernatant and filter it through a 0.2 μm pore size filter membrane to obtain a MXene quantum dot solution;

[0034] (3) The Co3O4 nanoneedles prepared in step (1) were irradiated with a UV lamp with a wavelength of 360 nm (the irradiation intensity of the UV lamp was 5 W m -2 ) is placed in the MXene quantum dot solution (concentration of 1×10 -3 wt%) and immersed in the solution for 8 h to obtain a MXene quantum dot tip heterojunction material, which was recorded as MXeneQDs2@Co3O4; in the material, the mass of MXene quantum dots loaded on the Co3O4 nanoneedles was 5 mg.

[0035] Example 3

[0036] The present invention provides a method for preparing a MXene quantum dot tip heterojunction material with high light-to-heat conversion efficiency, comprising:

[0037] (1) 0.2 g of Co(NO3)2·6H2O, 0.5 g of NH4F and 3 g of urea were dissolved in 30 mL of deionized water, stirred for 30 min to obtain a reaction solution, and the reaction solution was transferred to a 50 mL reactor; the nickel foam from which the surface oxides were removed by 3 M HCl was placed in the reaction solution and hydrothermaled at 120 ° C for 10 h; after the hydrothermal reaction was completed, the nickel foam was taken out, rinsed with deionized water 5 to 10 times, and blown dry with nitrogen to obtain the initial product Co(OH)F; finally, the initial product was air calcined at 400 to 500 ° C for 3 to 4 h to obtain a Co3O4 nanoneedle structure in situ grown on the nickel foam substrate and arranged in an array;

[0038] (2) Weigh 1 g of Ti3AlC2 raw material and place it in a 50 mL reactor, add 12 mL of 9 M HCl and 1.6 g of LiF, and etch at 40 ° C for 30 h; after etching, centrifuge and wash several times at 3500 rpm until the pH of the supernatant is neutral; after the last washing centrifugation, ultrasonicate the aqueous solution under N2 atmosphere for 3 h; after the ultrasonication, adjust the pH of the solution to 9-10 with ammonia water, and hydrothermally heat at 120 ° C for 10 h; after the hydrothermal reaction, take the supernatant and filter it through a 0.2 μm pore size filter membrane to obtain a MXene quantum dot solution;

[0039] (3) The Co3O4 nanoneedles prepared in step (1) were irradiated with a UV lamp having a wavelength of 360 nm and an irradiation intensity of 5 W m -2 Place the MXene quantum dot solution (concentration of 2×10 -3 wt%) and immersed in the solution for 8 h to obtain a MXene quantum dot tip heterojunction material, which was recorded as MXeneQDs3@Co3O4; in the material, the mass of the MXene quantum dots loaded on the Co3O4 nanoneedles was 10 mg.

[0040] Figure 1 This is a transmission electron microscope image of MXene quantum dots obtained in step (2) of Example 1; Figure 1 It can be seen from a that MXene quantum dots are evenly distributed; Figure 1 From the particle size distribution diagram b, the size of MXene quantum dots is mainly 1.5 nm.

[0041] Figure 2 The scanning electron microscope images of the Co3O4 nanoneedles prepared in step (1) and the MXene quantum dot tip heterojunction formed in step (3) in Example 1; Figure 2 a It can be seen that the Co3O4 nanoneedles are evenly distributed; Figure 2 b It can be seen that the surface of Co3O4 nanoneedles is slightly rough after loading MXene quantum dots.

[0042] Figure 3 This is a physical picture of the MXene quantum dot tip heterojunction material in Example 1, and the material is black.

[0043] Figure 4 This is a transmission electron micrograph of the Co3O4 nanoneedle prepared in step (1) of Example 1 and the MXene quantum dot tip heterojunction formed in step (3); it can be seen from the figure that the nanoneedle morphology is well maintained and the MXene quantum dots are evenly distributed on the nanoneedle.

[0044] Figure 5 This is the photothermal response diagram of the MXene quantum dot tip heterojunction material prepared in Example 1. Figure 5 As can be seen in a, under the irradiation of infrared light (200mW cm -2 ), the surface temperature of the MXene quantum dot tip heterojunction material quickly (5min) reached 93.9℃, while the surface temperatures of the MXene quantum dots prepared in step (2) (in this comparison process, the mass of the MXene quantum dots is the same as the effective mass of the MXene quantum dots in the MXene quantum dot tip heterojunction material) and the Co3O4 nanoneedles prepared in step (1) were 71.6℃ and 65.7℃, respectively. Figure 5 As can be seen in b, under the irradiation of xenon lamp (1kW cm -2 ), the surface temperature of the heterojunction material at the tip of the MXene quantum dots quickly reached 65.2°C, while the surface temperatures of the MXene quantum dots and Co3O4 nanoneedles were 53.1°C and 50.3°C.

[0045] Figure 6 The infrared emissivity of the MXene quantum dot tip heterojunction materials prepared in Example 1, Example 2 and Example 3. It can be seen from the figure that the full-band infrared emissivity of the MXene quantum dot tip heterojunction material of the present invention at room temperature is not less than 0.85.

Claims

1. A MXene quantum dot tip heterojunction material with high light-to-heat conversion efficiency, characterized by: The invention comprises a substrate and a Co3O4 nanoneedle array structure grown in situ on the substrate; the surface of the Co3O4 nanoneedles is loaded with Ti3C2MXene quantum dots, which are fixed to the surface of the Co3O4 nanoneedles through heterogeneous charge interaction forces, forming a tip heterojunction structure; the average particle size of the Ti3C2MXene quantum dots is 1-2 nm; The method for preparing the above-mentioned MXene quantum dot tip heterojunction material comprises the following steps: (1) Co3O4 nanoneedle structures arranged in an array are prepared on a nickel foam substrate using a hydrothermal method; (2) Under ultraviolet light, the product of step (1) is immersed in a Ti3C2MXene quantum dot solution to obtain a Ti3C2MXene quantum dot tip heterojunction material in which Ti3C2MXene quantum dots are loaded on Co3O4 nanoneedles; The preparation process of the MXene quantum dot solution is as follows: 1-1.2 g Ti3AlC2, 12-15 mL 9 M HCl and 1.6-2 g LiF are mixed and etched at 40 ° C for 24-30 hours; after etching, a few-layer MXene solution is prepared by multiple centrifugal washing and ultrasonic crushing; the pH of the MXene solution is adjusted to 9-10 with ammonia water, and then hydrothermal treatment is performed at 100-120 ° C for 10-12 hours; after the hydrothermal treatment, the supernatant is taken and filtered through a 0.2 μm pore size filter membrane to obtain a Ti3C2MXene quantum dot solution.

2. The MXene quantum dot tip heterojunction material with high light-to-heat conversion efficiency according to claim 1, characterized in that: The substrate is one of foam nickel, foam copper, carbon cloth or carbon paper.

3. The MXene quantum dot tip heterojunction material with high light-to-heat conversion efficiency according to claim 1, characterized in that: The mass of Ti3C2MXene quantum dots loaded on Co3O4 nanoneedles is 1~10mg.

4. The MXene quantum dot tip heterojunction material with high light-to-heat conversion efficiency according to claim 1, characterized in that: In step (1), the temperature of the hydrothermal reaction is 100-120° C., and the hydrothermal time is 6-12 h.

5. The MXene quantum dot tip heterojunction material with high light-to-heat conversion efficiency according to claim 1, characterized in that: In step (1), a Co3O4 nanoneedle structure arranged in an array is prepared on a nickel foam substrate. The specific process is as follows: 0.1~0.2g Co(NO3)2·6H2O, 0.3~0.5g NH4F and 2~3g urea are dissolved in 20~30mL deionized water, and stirred to obtain a reaction solution; the substrate is placed in the reaction solution and hydrothermally heated at 100~120℃ for 10~20h; after the hydrothermal reaction is completed, a primary product Co(OH)F is obtained; the primary product is first rinsed with deionized water, then blown dry with nitrogen, and finally calcined in air at 400~500℃ for 3~4h to obtain a Co3O4 nanoneedle structure in situ grown on the substrate and arranged in an array.

6. The MXene quantum dot tip heterojunction material with high light-to-heat conversion efficiency according to claim 1, characterized in that: In step (2), the irradiation intensity of the UV lamp is 5~6W m -2 .

7. The MXene quantum dot tip heterojunction material with high light-to-heat conversion efficiency according to claim 1, characterized in that: In step (2), the soaking time is 6 to 8 hours.

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