A Ta2O5 / rGO heterostructure aerogel, its preparation method and application

Abstract

This invention discloses a Ta₂O₅ / rGO heterostructure aerogel, its preparation method, and its applications. The preparation method involves: uniformly mixing a TaS₂ nanosheet aqueous dispersion, a graphene oxide aqueous dispersion, and ascorbic acid to obtain a mixture; subjecting the resulting mixture to a hydrothermal reaction; and after the hydrothermal reaction, sequentially dialysis, freeze-drying, and freeze-drying the product system to obtain the final product. The Ta₂O₅ / rGO heterostructure aerogel of this invention exhibits superior microwave absorption properties, good thermal stability, and mechanical properties, showing broad potential applications in electronic devices that rely on the characteristics of 2D materials.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials and electromagnetic wave absorption, specifically relating to a Ta2O5 / rGO heterostructure aerogel, its preparation method, and its application. Background Technology

[0002] The rapid development and ever-increasing demand for wireless electronic devices have led to undesirable electromagnetic pollution, which has adversely affected human health and the reliability of electronic devices. Therefore, there is a high demand for efficient microwave absorbers to dissipate unwanted electromagnetic waves. Although existing research has made some progress, existing microwave absorbing materials inevitably suffer from drawbacks such as narrow electromagnetic wave absorption bands, low absorption capacity, instability of the absorbing materials, and complex preparation processes. To date, constructing heterostructure microwave absorbing materials remains an effective strategy. For example, Man et al. (Advanced Functional Materials 2021, 31(19)) improved EMW absorption performance by manipulating the MoS2 phase content and introducing abundant dipoles through a large 2H / 1T heterostructure interface. The metal-semiconductor mixed phase enhanced electron transfer capability. Che et al. (Advanced Functional Materials 2021, 32(6)) found that when the content of 2H phase and 1T phase in NbS2 is close to 1:1, the multiphase structure and good conductivity increase dielectric loss and exhibit better EMW absorption performance. Yan et al. (Chemical Engineering Journal 2021, 41) constructed a two-dimensional SnO / SnO2 heterojunction to achieve enhanced interfacial polarization, which is beneficial for electromagnetic wave absorption. They also established the correlation between work function, charge separation, and interfacial polarization. Che et al. (Chemical Engineering Journal 2020, 383) prepared a core-shell structured Ni@C@ZnO absorbing material. They constructed a Schottky contact at the interface between the conductor Ni@C and the ZnO semiconductor, generating a strong interfacial polarization effect and exhibiting excellent microwave absorption performance. In addition, the heterostructure of the absorbing material is beneficial for impedance matching and multiple internal scattering, further optimizing the EMW absorption performance. Huang et al. (Small 2020, 16(30), e2001686) constructed a MoO2 / C / rGO dielectric absorbing material. As a typical dielectric material, MoO2 has high charge carrier mobility and good oxidation resistance. The uniform MoO2 clusters generate more polarization at the interface and provide reasonable dielectric loss and excellent impedance matching performance, thus significantly enhancing the absorption capability of low-frequency electromagnetic waves.Long et al. (Nanomicro Lett 2023, 15(1), 183) prepared oxygen-vacancy-rich Nb2O5 semiconductors and confined them in carbon nanosheets (ov-Nb2O5 / CNS) to enhance dielectric polarization and achieve high attenuation. The oxygen-vacancy-rich Nb2O5 semiconductors significantly promoted the polarization relaxation, electromagnetic response and impedance matching of ov-Nb2O5 / CNS, thereby achieving extremely high attenuation performance. The abundant Nb2O5-carbon heterostructure interface can enhance interfacial polarization loss, while the presence of oxygen vacancies endows the Nb2O5 semiconductor with abundant charge separation sites to enhance electric dipole polarization.

[0003] Existing microwave absorbing materials inevitably suffer from drawbacks such as narrow electromagnetic wave absorption bands, low absorption capacity, material instability, and complex fabrication processes. Therefore, there is an urgent need to explore novel microwave absorbing materials and their fabrication methods to improve their electromagnetic response capabilities, optimize impedance matching, and expand the electromagnetic wave response range. Summary of the Invention

[0004] To address the shortcomings of existing electromagnetic wave absorbing materials, such as narrow electromagnetic wave absorption bands, low absorption capacity, material instability, and complex preparation processes, this invention provides a Ta₂O₅ / rGO heterostructure aerogel, its preparation method, and its applications. The tantalum pentoxide / reduced graphene oxide (Ta₂O₅ / rGO) heterostructure aerogel material exhibits excellent electromagnetic wave absorption performance. This invention provides a simple and innovative aerogel preparation process.

[0005] The specific technical solution of this invention is as follows:

[0006] This invention provides a method for preparing Ta2O5 / rGO heterostructured aerogel, comprising the following steps:

[0007] (1) Mix TaS2 nanosheet aqueous dispersion, graphene oxide aqueous dispersion and ascorbic acid evenly to obtain a mixture;

[0008] (2) The resulting mixture was subjected to a hydrothermal reaction;

[0009] (3) After the hydrothermal reaction is completed, the product system obtained by the hydrothermal reaction is subjected to dialysis, freezing treatment and freeze drying in sequence to obtain Ta2O5 / rGO heterostructure aerogel.

[0010] Further, in step (1), TaS2 is 0 to 100 parts by mass (not 0), ascorbic acid is 0 to 100 parts by mass, and graphene oxide is 0 to 100 parts by mass (not 0).

[0011] Further, in step (1), TaS2 is 0 to 100 parts by mass (not 0), ascorbic acid is 0 to 100 parts by mass (not 0), and graphene oxide is 0 to 100 parts by mass (not 0).

[0012] Preferably, the amount of TaS2 is 20-80 parts by mass, the amount of ascorbic acid is 20-80 parts by mass, and the amount of graphene oxide is 20-80 parts by mass;

[0013] Preferably, TaS2 is 80 parts by mass, ascorbic acid is 0 parts by mass, and graphene oxide is 20 parts by mass;

[0014] Preferably, TaS2 is 40 parts by mass, ascorbic acid is 60 parts by mass, and graphene oxide is 60 parts by mass.

[0015] Further, in step (1), the concentration of the TaS2 nanosheet aqueous dispersion is 5-20 mg / mL, and the concentration of the graphene oxide aqueous dispersion is 5-20 mg / mL.

[0016] Preferably, the concentration of the TaS2 nanosheet aqueous dispersion is 10 mg / mL, and the concentration of the graphene oxide aqueous dispersion is 10 mg / mL.

[0017] Further, in step (1), the mixing method is ultrasonic dispersion, mechanical stirring, or vortex oscillator stirring;

[0018] Preferably, the ultrasonic dispersion conditions are 500W for 10-30 minutes, the mechanical stirring conditions are 100-500 rpm for 10-30 minutes, and the vortex oscillator stirring time is 10-30 minutes.

[0019] Furthermore, in step (2), the hydrothermal reaction temperature is 65–90°C and the reaction time is 3–5 h;

[0020] Preferably, the hydrothermal reaction conditions are 65°C for 3 hours, followed by 70°C for 1 hour.

[0021] Further, in step (3), the dialysis is performed using an ethanol-water solution, wherein the volume percentage concentration of the ethanol-water solution is 5% to 20%, and the dialysis time is 6 to 24 hours.

[0022] Preferably, the volume percentage concentration of the ethanol-water solution is 10%, and the dialysis time is 6 hours.

[0023] Furthermore, in step (3), the freezing treatment is performed by a low-temperature freezer or liquid nitrogen freezing, and the process is non-directional freezing or directional freezing;

[0024] Preferably, the freezing treatment is non-directional freezing at -25°C for 12 hours.

[0025] In step (3), the freeze drying is performed at -60°C (pressure <10Pa) for 48 hours.

[0026] Another aspect of the present invention provides a Ta2O5 / rGO heterostructure aerogel prepared by the aforementioned preparation method.

[0027] Another aspect of the present invention provides the application of the Ta2O5 / rGO heterostructure aerogel in the preparation of electromagnetic wave absorbing materials.

[0028] The principle of preparing Ta2O5 / rGO heterointerfacial aerogels in this invention is as follows: TaS2 nanosheets and GO have similar hydrophilicity and negative charge, making it easy to form a stable aqueous suspension. Under hydrothermal reaction, TaS2 nanosheets react on the GO surface to generate highly dielectric tantalum pentoxide (Ta2O5) and simultaneously produce SO2. SO2 reacts with water to form HSO3, which has a reducing effect. - Subsequently, two SN2 affinity reactions and a thermal elimination reaction occurred, during which HSO3 was reduced. - Oxidized to SO4 2- As the reduction process occurs, a Ta₂O₅ / rGO heterostructure interface is formed, and the corresponding aerogel is obtained through freeze-drying. Therefore, by adjusting the mass ratio of TaS₂ to GO and the degree of reduction, Ta₂O₅ / rGO heterostructure aerogels with different content ratios can be synthesized. It can be expected that the formation of the Ta₂O₅ / rGO heterostructure interface will greatly promote charge separation and dipole formation and induce polarization, thereby enhancing dielectric polarization loss.

[0029] The beneficial effects of this invention are as follows:

[0030] (1) The present invention adopts a simple, efficient and feasible graphene oxide reduction strategy and constructs an aerogel structure;

[0031] (2) The Ta2O5 / rGO heterostructure aerogel of the present invention exhibits superior microwave absorption performance. The Ta2O5 / rGO heterostructure aerogel prepared by reducing GO with TaS2 nanosheets (Example 4) has a minimum reflection loss (RLmin) of -61.93dB and an effective absorption bandwidth of 6.76GHz (11.24-18.00GHz); the aerogel prepared by reducing GO with ascorbic acid in conjunction with TaS2 (Example 6) achieves an ultra-high effective absorption bandwidth of 8.54GHz (7.80-16.34GHz) and an RLmin of -30.21dB.

[0032] (3) The Ta2O5 / rGO heterostructure aerogel of this invention exhibits good thermal stability and mechanical properties. The aerogel prepared by ascorbic acid-co-assisted TaS2 reduction of GO (Example 6) has a thermal conductivity of only 36 mW / m². -1 K -1 It has excellent thermal insulation and flame retardant properties, can withstand 95% compression deformation without damage, and has a stress of 14.9 kPa under 50% compression.

[0033] (4) The novel Ta2O5 / rGO heterostructure aerogel prepared by this invention has broad potential application prospects in the field of electronic devices that rely on the properties of 2D materials. Attached Figure Description

[0034] Figure 1 Image of aerogel sample;

[0035] Figure 2 SEM images of the aerogel samples prepared in Examples 1-4 are shown.

[0036] Figure 3 SEM images of the aerogel samples prepared in Examples 5-8 are shown.

[0037] Figure 4 SEM images of the prepared aerogel samples from Comparative Examples 1-5 are shown.

[0038] Figure 5 The thermal stability and compressive stress-strain curves of the aerogel sample prepared in Example 6 are shown. Detailed Implementation

[0039] To better understand the present invention, it is now further described with reference to the following embodiments and accompanying drawings. The embodiments are for illustrative purposes only and do not limit the invention in any way. In the embodiments, all original reagents and materials are commercially available, and experimental methods not specifically specified are conventional methods and conditions well known in the art, or according to the conditions recommended by the instrument manufacturer.

[0040] In a specific embodiment of the present invention, the preparation method of Ta2O5 / rGO heterostructure aerogel with excellent electromagnetic wave absorption performance includes the following steps:

[0041] (1) Add an appropriate amount of 10 mg / mL TaS2 nanosheet aqueous dispersion, an appropriate amount of 10 mg / mL graphene oxide aqueous dispersion, and an appropriate amount of ascorbic acid to a 12 mL cylindrical SpeedMixer. TM Place in a PP mixing tank and mechanically stir at 500 rpm for 30 minutes;

[0042] (2) Place the mixing tank containing the raw materials into a polytetrafluoroethylene container, and perform hydrothermal treatment at 65°C for 3 hours and at 70°C for 1 hour.

[0043] (3) After the reaction is complete, the mixing tank is removed and dialyzed in 10 vol% ethanol solvent for 6 h. After dialyzing, the mixing tank containing the raw materials is frozen at -25℃ for 12 h. Finally, it is freeze-dried at -60℃ (pressure <10 Pa) to obtain the aerogel. The obtained aerogel can be cylindrical, rectangular, or other shapes depending on the mixing tank, and the thickness can be adjusted arbitrarily according to the mass fraction and amount of raw materials added.

[0044] The difference between Examples 1-8 and Comparative Examples 1-5 lies in the different amounts of TaS2 nanosheets, graphene oxide, and ascorbic acid used in step (1). The methods in steps (2) and (3) are as described above. Taking Examples 4, 6, and Comparative Example 2 as examples, the amounts of TaS2 nanosheets, graphene oxide, and ascorbic acid used in step (1) are explained.

[0045] Example 4

[0046] Step (1) is as follows: TaS2 nanosheet aqueous dispersion (2.4 mL, 10 mg / mL) and graphene oxide aqueous dispersion (0.6 mL, 10 mg / mL) are added to 12 mL cylindrical SpeedMixer. TM In a PP mixing tank, mechanically stir at 500 rpm for 30 minutes.

[0047] Example 6

[0048] Step (1) is as follows: Add ascorbic acid (18 mg), TaS2 nanosheet aqueous dispersion (1.2 mL, 10 mg / mL) and graphene oxide aqueous dispersion (1.8 mL, 10 mg / mL) to a 12 mL cylindrical SpeedMixer. TM In a PP mixing tank, mechanically stir at 500 rpm for 30 minutes.

[0049] Comparative Example 2

[0050] Step (1) is as follows: Add ascorbic acid (18 mg) and graphene oxide aqueous dispersion (1.8 mL, 10 mg / mL) to a 12 mL cylindrical SpeedMixer. TM In a PP mixing tank, mechanically stir at 500 rpm for 30 minutes.

[0051] The mass fractions of TaS2 nanosheets, graphene oxide, and ascorbic acid in Examples 1-8 and Comparative Examples 1-5 are shown in Table 1. For other examples and comparative examples, refer to Examples 4, 6, and 2. Weigh TaS2 nanosheets, graphene oxide, and ascorbic acid according to the proportions to prepare aerogels.

[0052] Table 1

[0053] Example 1 20 portions by weight 0 parts by weight 80 portions Example 2 40 portions by weight 0 parts by weight 60 portions by weight Example 3 60 portions by weight 0 parts by weight 40 portions by weight Example 4 80 portions 0 parts by weight 20 portions by weight Example 5 20 portions by weight 80 portions 80 portions Example 6 40 portions by weight 60 portions by weight 60 portions by weight Example 7 60 portions by weight 40 portions by weight 40 portions by weight Example 8 80 portions 20 portions by weight 20 portions by weight Comparative Example 1 0 parts by weight 80 portions 80 portions Comparative Example 2 0 parts by weight 60 portions by weight 60 portions by weight Comparative Example 3 0 parts by weight 40 portions by weight 40 portions by weight Comparative Example 4 0 parts by weight 20 portions by weight 20 portions by weight Comparative Example 5 0 parts by weight 80 portions 80 portions

[0054] Figure 1 Images of aerogel samples from Examples 1-8 and Comparative Examples 1-5 are shown. Figure 2 This shows SEM images of the aerogel samples prepared in Examples 1-4. Figure 3 This shows SEM images of the aerogel samples prepared in Examples 5-8. Figure 4 The images show SEM images of the aerogel samples prepared in Comparative Examples 1-5. Figure 5 The thermal stability and compressive stress-strain curves of the aerogel sample prepared in Example 6 are shown in Table 2. The microwave absorption properties of the aerogels from Examples 1-8 and Comparative Examples 1-5 are shown in Table 2.

[0055] The results show that the Ta₂O₅ / rGO heterostructure aerogel prepared in Example 4 has a minimum reflection loss (RLmin) of -61.93 dB and an effective absorption bandwidth of 6.76 GHz (11.24-18.00 GHz). The aerogel prepared in Example 6 by ascorbic acid-assisted TaS₂ reduction of GO achieved an ultra-high effective absorption bandwidth of 8.54 GHz (7.80-16.34 GHz), an RLmin of -30.21 dB, and a thermal conductivity of only 36 mW / m². -1 K -1 It has excellent thermal insulation and flame retardant properties, can withstand 95% compression deformation without damage, and has a stress of 14.9 kPa under 50% compression.

[0056] Table 2

[0057] Example 1 -1.37dB 0GHz Example 2 -3.86dB 0GHz Example 3 -9.73dB 0GHz Example 4 -61.93dB (15.71GHz, 2.6mm) 6.76GHz, 2.8mm Example 5 -11.73dB (16.56GHz, 1.8mm) 5.06GHz, 2.0mm Example 6 -30.21dB (17.92GHz, 2.4mm) 8.54GHz, 3.6mm Example 7 -18.94dB (17.02GHz, 2.0mm) 7.18GHz, 2.2mm Example 8 -20.54dB (11.37GHz, 2.0mm) 6.08GHz, 2.0mm Comparative Example 1 -8.87dB 0GHz Comparative Example 2 -11.26dB (10.82GHz, 2.2mm) 1.28GHz, 2.2mm Comparative Example 3 -13.07dB (17.62GHz, 1.8mm) 2.30GHz, 2.0mm Comparative Example 4 -17.51dB (17.75GHz, 1.8mm) 5.48GHz, 2.2mm Comparative Example 5 -18.81dB (9.16GHz, 4.8mm) 5.41GHz, 3.2mm

[0058] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. The application of a Ta2O5 / rGO heterostructure aerogel in the preparation of electromagnetic wave absorbing materials, characterized in that, The preparation method of the Ta2O5 / rGO heterostructure aerogel includes the following steps: (1) Mix TaS2 nanosheet aqueous dispersion, graphene oxide aqueous dispersion and ascorbic acid evenly to obtain a mixture; (2) The resulting mixture is subjected to a hydrothermal reaction; (3) After the hydrothermal reaction is completed, the product system obtained by the hydrothermal reaction is subjected to dialysis, freezing treatment and freeze drying in sequence to obtain Ta2O5 / rGO heterostructure aerogel. In step (1), TaS2 is 20-80 parts by mass, ascorbic acid is 20-80 parts by mass, and graphene oxide is 20-80 parts by mass; In step (1), the concentration of the TaS2 nanosheet aqueous dispersion is 5-20 mg / mL, and the concentration of the graphene oxide aqueous dispersion is 5-20 mg / mL. In step (2), the hydrothermal reaction temperature is 65-90 °C and the reaction time is 3-5 h.

2. The application according to claim 1, characterized in that, In step (1), TaS2 is 40 parts by mass, ascorbic acid is 60 parts by mass, and graphene oxide is 60 parts by mass.

3. The application according to claim 1, characterized in that, In step (1), the concentration of the TaS2 nanosheet aqueous dispersion is 10 mg / mL, and the concentration of the graphene oxide aqueous dispersion is 10 mg / mL.

4. The application according to claim 1, characterized in that, In step (1), the mixing method is ultrasonic dispersion, mechanical stirring or vortex oscillator stirring.

5. The application according to claim 4, characterized in that, In step (1), the ultrasonic dispersion conditions are 500W for 10~30 min, the mechanical stirring conditions are 100~500 rpm for 10~30 min, and the vortex oscillator stirring time is 10~30 min.

6. The application according to claim 1, characterized in that, In step (2), the hydrothermal reaction conditions are 65 °C for 3 h and then 70 °C for 1 h.

7. The application according to claim 1, characterized in that, In step (3), the dialysis is performed using an ethanol-water solution, the volume percentage concentration of which is 5% to 20%, and the dialysis time is 6 to 24 hours. The freezing process is performed using a low-temperature freezer or liquid nitrogen freezing, and the process is either non-directional freezing or directional freezing. The freeze-drying process was carried out at -60 °C and a pressure of <10 Pa for 48 h.

8. The application according to claim 7, characterized in that, In step (3), the volume percentage concentration of the ethanol aqueous solution is 10%, and the dialysis time is 6 h; The freezing treatment was non-directional freezing at -25 ℃ for 12 h.

Images