High-entropy two-dimensional transition metal MXene broadband light absorption material and preparation method thereof

Abstract

The invention relates to a high-entropy two-dimensional transition metal MXene broadband light-absorbing material which is composed of an M-layer element, an A-layer element and graphite powder, an A-layer Al element is etched through a LiF-HCl mixed solution with the mass concentration of 40% to form a two-dimensional layered structure, and the chemical general formula of the material is M3C2; wherein the elements of the M layer are any five metal elements of Ti, Zr, Nb, Mo, Hf and W, and the metal atoms are in an equal molar ratio; and the element of the A layer is Al. Meanwhile, the invention also provides a preparation method of the material. The preparation method is easy, high in repeatability and high in production efficiency and can be used for industrial large-scale production, the solar energy absorption rate of the prepared broadband light absorption material within the waveband range of 0.3-2.5 microns is 0.891-0.910, and the broadband light absorption material can be widely applied to solar photo-thermal conversion materials.

Description

TECHNICAL FIELD

[0001] The application relates to a light-absorbing material, in particular to a high-entropy two-dimensional transition metal MXene wide-band light-absorbing material and a preparation method thereof. BACKGROUND

[0002] With the promotion of the "double carbon" goal and the transformation of global energy structure, the large-scale utilization of solar energy as a clean and renewable energy source has become a key direction. The light-heat conversion technology has become one of the core paths of solar energy utilization because of its high energy storage density and wide application scenarios (such as photo-thermal power generation, seawater desalination, and industrial waste heat recovery). As the "core engine" of the light-heat conversion system, the absorption capacity of the light-absorbing material in the main energy band of solar radiation directly determines the conversion efficiency - 98% of the energy in the solar spectrum is concentrated in the 0.3-0.38 μm ultraviolet region, the 0.38-0.78 μm visible light region, and the 0.78-2.5 μm near-infrared region. Therefore, the wide-band absorption rate (a) of 0.3-2.5 μm needs to reach more than 0.95 to meet the actual needs of efficient light-heat utilization. The essence of light absorption is that the photon energy drives the electron transition, and the electronic structure (such as the band gap width and the electron state density near the Fermi level) of the material is the core factor determining the absorption performance. At present, the main light-absorbing materials are mainly divided into three categories, but all have significant limitations: Traditional metal-based materials (such as Au, Ag nanoparticles, Mo, and W thin films): relying on the localized surface plasmon resonance (LSPR) or d-band transition of metal d electrons to realize light absorption, but the LSPR effect is only concentrated in a specific narrow band (such as the absorption peak of Au nanoparticles is about 520 nm), and the reflectivity of metal thin film is high in the near-infrared region (such as the reflectivity of Mo thin film is >30% at 1.5 μm band), which cannot cover the full solar spectrum; semiconductor-based materials (such as TiO2, Si, and CuInGaSe2): absorbing photons through valence band-conduction band electron transition, but the band gap width is fixed (such as anatase TiO2 has a band gap of 3.2 eV, only absorbing <387 nm ultraviolet light; single crystal silicon has a band gap of 1.12 eV, with an absorption cutoff wavelength of about 1100 nm), and the near-infrared absorption capacity is poor, and most semiconductors are prone to crystal transformation at high temperatures (such as TiO2 is converted into rutile phase above 600 ℃, and the absorption performance decreases by 40%); carbon-based materials (such as graphene, carbon nanotubes, and mesoporous carbon): realizing wide-band absorption by means of conjugated π-electron system, but its chemical stability is poor - it is easy to be oxidized to CO2 in air environment above 200 ℃, and the carbon-based material has weak adhesion with the substrate, which is easy to peel off during thermal cycling, and the service life is usually less than 1000 hours. To break through the limitations of traditional materials, high-entropy materials have become a research hotspot for wide-band light-absorbing materials due to their characteristic of "multi-principal element synergistic regulation of electronic structure". High-entropy materials (such as high-entropy oxides, high-entropy sulfides, and high-entropy MXenes) can achieve continuous distribution of electron state density near the Fermi level through the entropy-increasing effect of multiple metal elements, theoretically covering the electronic transition requirements of the entire solar spectrum. For example, Zhang et al. prepared (CoNiCuZnMn)O x High-entropy oxides (Journal of Materials Chemistry A, 2022, 10: 15243) have an absorption rate of 0.88 in the 0.3-2.5 μm waveband, but the band gap disorder is enlarged due to the chaotic valence state of metal ions, and the near-infrared region (1.5-2.5 μm) absorption efficiency is still less than 60%; Li's team developed (MoNbTaWTi)S2 high-entropy sulfide (ACS Applied Materials & Interfaces, 2023, 15: 28761), which improved visible light absorption through S-p orbital and metal-d orbital hybridization, but sulfides are prone to hydrolysis (absorption rate decreases by 25% within 30 days in a humidity > 60% environment) and decomposition at high temperatures (> 150 ℃) to produce toxic gases, limiting practical applications. Currently, with the development of technology, there is an urgent need for wide-band light-absorbing materials. MXene materials have potential, but traditional single-component materials have problems such as impedance mismatch and single loss mechanism. The high-entropy strategy can adjust the electrical conductivity and polarization loss of the material. Therefore, the preparation of high-entropy MXene wide-band light-absorbing materials is expected to solve existing problems and achieve breakthroughs in the fields of optoelectronics and electromagnetic management. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a high-entropy two-dimensional transition metal MXene wide-band light-absorbing material with good performance.

[0004] Another technical problem to be solved by the present application is to provide a preparation method for the high-entropy two-dimensional transition metal MXene wide-band light-absorbing material.

[0005] To solve the above problems, the high-entropy two-dimensional transition metal MXene wide-band light-absorbing material according to the present application is characterized in that the material is composed of M-layer elements, A-layer elements, and graphite powder, and forms a two-dimensional layered structure by etching the A-layer Al element with a LiF-HCl mixed solution with a mass concentration of 40%, and the chemical formula is M3C2; wherein: the M-layer elements are any five metal elements selected from Ti, Zr, Nb, Mo, Hf, and W, and the metal atoms are in equimolar ratio; the A-layer elements are Al.

[0006] The LiF-HCl mixed solution with a mass concentration of 40% refers to a mixed solution obtained by dissolving LiF powder in concentrated HCl.

[0007] The solar energy absorption rate of the material in the 0.3-2.5 μm wave band range is 0.891-0.910.

[0008] The preparation method of the high-entropy two-dimensional transition metal MXene wide-band light-absorbing material has the characteristics that first, M-layer element powder, Al powder and graphite powder are mixed in a molar ratio of 2-5:1:1, the M-layer element powder refers to any five of Ti, Zr, Nb, Mo, Hf and W, and the metal atoms are in an equimolar ratio; the mixed powder is ground in anhydrous ethanol as a medium at 580 r / min -1 After ball milling for 12-24 hours, a uniformly mixed powder is obtained; then, the mixed powder is transferred to a spark plasma sintering furnace, heated under vacuum, and then ground to obtain a ground powder; the ground powder is etched with a LiF-HCl mixed solution with a mass concentration of 40%, and finally, the ground powder is vacuum dried to a water content of not more than 2.5%, thereby obtaining the high-entropy two-dimensional transition metal MXene wide-band light-absorbing material.

[0009] The average particle size of the M-layer element powder and the Al powder is 300-800 mesh.

[0010] The heating condition is 1400-1600 ℃, and the heating time is 10-15 min.

[0011] The mass ratio of the LiF-HCl mixed solution to the ground powder is 20-25:1.

[0012] The etching Al layer treatment condition is that the temperature is 40-60 ℃, and the time is 60-72 hours.

[0013] Compared with the prior art, the present application has the following advantages: 1. Considering that different metals only exhibit strong interband transitions in a specific spectral range due to their electronic structure, which is not conducive to the absorption of the entire solar spectrum, the present application adopts an equimolar ratio of Ti, Zr, Nb, Mo, Hf and W to form a high-entropy MXene, which fills the d-band distribution near the Fermi level by combining multiple metals, thereby realizing the absorption and utilization of the entire solar spectrum.

[0014] 2. The present application adopts a spark plasma sintering method to prepare a high-entropy MXene layered structure: the spark plasma sintering (SPS) has fast heating, short time consumption, low temperature energy saving, high product purity, excellent performance and controllable process.

[0015] 3. The present application requires simple equipment, has an easy preparation method, strong repeatability, high production efficiency and can be used for industrial large-scale production.

[0016] 4、The wide-band light absorption material prepared by the application has a solar energy absorption rate of 0.891-0.910 in the 0.3-2.5 μm wave band range, and can be widely applied to solar light-heat conversion materials. BRIEF DESCRIPTION OF DRAWINGS

[0017] The specific embodiments of the application will be further described in detail below with reference to the accompanying drawings.

[0018] Figure 1 The XRD spectrum of the (TiZrNbMoHf)3C2 wide-band light absorption material powder of the embodiment 1 of the application.

[0019] Figure 2 The absorption spectrum (0.3-2.5 μm) of the (TiZrNbMoHf)3C2 wide-band light absorption material powder of the embodiment 1 of the application.

[0020] Figure 3 The absorption spectrum (0.3-2.5 μm) of the (TiZrNbMoHf)3C2 wide-band light absorption material powder of the embodiment 1 of the application. DETAILED DESCRIPTION

[0021] A high-entropy two-dimensional transition metal MXene wide-band light absorption material, which is composed of M layer elements, A layer elements and graphite powder, and forms a two-dimensional layered structure by etching the A layer Al element with a 40% mass concentration LiF-HCl mixed solution, and has a chemical general formula of M3C2; wherein: the M layer elements are any five metal elements of Ti, Zr, Nb, Mo, Hf and W, and the metal atoms are in an equimolar ratio; the A layer elements are Al.

[0022] The 40% mass concentration LiF-HCl mixed solution refers to a mixed solution obtained by dissolving LiF powder in concentrated HCl.

[0023] The material has a solar energy absorption rate of 0.891-0.910 in the 0.3-2.5 μm wave band range.

[0024] A preparation method of a high-entropy two-dimensional transition metal MXene wide-band light absorption material: first, mix M layer element powder, Al powder and graphite powder in a molar ratio of 2-5:1:1, wherein the M layer element powder refers to any five of Ti, Zr, Nb, Mo, Hf and W, and the metal atoms are in an equimolar ratio; the average particle size of the M layer element powder and the Al powder is 300-800 mesh; and then, in anhydrous ethanol as a medium, etch the mixed powder at 580 r / min -1The mixture is ball-milled for 12-24 hours to obtain a homogeneous powder. Then, the powder is transferred to a spark plasma sintering furnace and heated at 1400-1600 °C for 10-15 min under vacuum (10 Pa). After grinding, the powder is further ground. The ground powder is then used to etch an Al layer with a 40% LiF-HCl solution at 40-60 °C for 60-72 hours. The mass ratio of the LiF-HCl solution to the ground powder is 20-25:1 (g / g). Finally, the powder is ground and vacuum-dried until the moisture content is no higher than 2.5%.

[0025] Example 1: First, the M-layer element powder, Al powder, and graphite powder were mixed in a 2:1:1 molar ratio. The M-layer element powder refers to Ti, Zr, Nb, Mo, and Hf, with an equimolar ratio of metal atoms. The average particle size of the M-layer element powder and Al powder was 300-800 mesh. The mixture was then heated at 580 r / min using 20 ml of anhydrous ethanol as the medium. -1 The mixture was ball-milled for 12 hours to obtain a homogeneous powder. Then, the powder was transferred to a spark plasma sintering furnace and heated at 1400 °C for 10 min under vacuum. After grinding, the powder was further ground. The ground powder was then used to etch an Al layer at 40 °C for 60 hours with a 40% LiF-HCl solution. The mass ratio of the LiF-HCl solution to the ground powder was 25:1 (g / g). Finally, the mixture was ground and vacuum-dried until the moisture content was no more than 2.5%, yielding the (TiZrNbMoHf)3C2 light-absorbing material.

[0026] X-ray diffraction experiments were performed on the obtained (TiZrNbMoHf)3C2 light-absorbing material, and the results are as follows: Figure 1 As shown in the figure, the synthesized MAX phase has almost the same X-ray diffraction (XRD) mode, indicating that the structural fluctuations caused by the introduction of metal elements are small. The sharp and strong diffraction peak of Ti3AlC2PDF#00-052-0875 is in very good agreement with the reported MAX phase.

[0027] The light absorption properties of the obtained (TiZrNbMoHf)3C2 light-absorbing material were evaluated: Test method: The absorption spectrum in the range of 0.3~2.5 μm was obtained by using a Lambda 950 UV / Vis / NIR spectrophotometer manufactured by PerkinElmer, USA and a Bruker Tensor 27 infrared spectrometer, Germany. The solar energy absorption rate was then obtained according to the national standard GB / T 26974-2011.

[0028] The results are obvious. Figure 2 ,Figure 3 The results show that the solar energy absorption rate of the (TiZrNbMoW)3C2 light-absorbing material in the 0.3-2.5 μm wave band is 0.892-0.910.

[0029] Example 2 First, the M layer element powder, Al powder and graphite powder are mixed in a molar ratio of 3:1:1, the M layer element powder refers to Ti, Zr, Nb, Mo and W, and the metal atoms are in an equal molar ratio; the average particle size of the M layer element powder and the Al powder is 300-800 mesh. 20 ml of anhydrous ethanol is used as a medium to ball mill at 580 r / min -1 After ball milling for 24 hours, a uniformly mixed powder is obtained; then, the mixed powder is transferred to a spark plasma sintering furnace, heated at 1500°C for 13 min under vacuum conditions, and then ground to obtain a ground powder; the ground powder is etched with a 40% LiF-HCl mixed solution at 50°C for 66 hours, and the mass ratio (g / g) of the LiF-HCl mixed solution to the ground powder is 20:1. Finally, the ground powder is vacuum dried to a water content of not more than 2.5%, thereby obtaining a (TiZrNbMoW)3C2 light-absorbing material.

[0030] The light absorption performance of the obtained (TiZrNbMoW)3C2 light-absorbing material is evaluated: The test method and the amount of test sample are the same as in Example 1.

[0031] The results show that the solar energy absorption rate of the (TiZrNbMoW)3C2 light-absorbing material in the 0.3-2.5 μm wave band is 0.892-0.910.

[0032] Example 3 First, the M layer element powder, Al powder and graphite powder are mixed in a molar ratio of 5:1:1, the M layer element powder refers to Ti, Zr, Nb, W and Hf, and the metal atoms are in an equal molar ratio; the average particle size of the M layer element powder and the Al powder is 300-800 mesh. 20 ml of anhydrous ethanol is used as a medium to ball mill at 580 r / min -1 After ball milling for 24 hours, a uniformly mixed powder is obtained; then, the mixed powder is transferred to a spark plasma sintering furnace, heated at 1500°C for 13 min under vacuum conditions, and then ground to obtain a ground powder; the ground powder is etched with a 40% LiF-HCl mixed solution at 50°C for 66 hours, and the mass ratio (g / g) of the LiF-HCl mixed solution to the ground powder is 20:1. Finally, the ground powder is vacuum dried to a water content of not more than 2.5%, thereby obtaining a (TiZrNbMoW)3C2 light-absorbing material.

[0033] The light absorption performance of the obtained (TiZrNbWHf)3C2 light absorption material is evaluated: The test method and the test sample dosage are the same as those in Example 1.

[0034] The results show that the (TiZrNbWHf)3C2 light absorption material has a solar energy absorption rate of 0.891-0.908 in the 0.3-2.5 μm wavelength band.

[0035] The above merely describes specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be encompassed in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A high-entropy two-dimensional transition metal MXene broadband light-absorbing material, characterized in that: The material is composed of M layer elements, A layer elements and graphite powder, and a two-dimensional layered structure is formed by etching the A layer Al element with a LiF-HCl mixed solution with a mass concentration of 40%, and the chemical general formula is M3C2; wherein the M layer elements are any five metal elements selected from Ti, Zr, Nb, Mo, Hf and W, and the metal atoms are in an equimolar ratio; and the A layer elements are Al.

2. The high-entropy two-dimensional transition metal MXene broadband light-absorbing material of claim 1, wherein: The LiF-HCl mixed solution with a mass concentration of 40% refers to a mixed solution obtained by dissolving LiF powder in concentrated HCl.

3. The high-entropy two-dimensional transition metal MXene broadband light-absorbing material of claim 1, wherein: The solar energy absorption rate of the material in the 0.3-2.5 μm wave band range is 0.891-0.

910.

4. The method of any one of claims 1-3, wherein the method comprises: preparing a high-entropy two-dimensional transition metal MXene wide-band light-absorbing material by the following steps: preparing a precursor material; and performing a chemical reaction on the precursor material to obtain the high-entropy two-dimensional transition metal MXene wide-band light-absorbing material. First, M layer element powder, Al powder, graphite powder are mixed according to the molar ratio of 2-5:1:1, M layer element powder refers to any five of Ti, Zr, Nb, Mo, Hf and W, and the metal atoms are in equal molar ratio; anhydrous ethanol is used as medium at 580 r / min -1 Ball milling for 12-24 hours, that is, a uniformly mixed powder is obtained; then, the mixed powder is transferred to a spark plasma sintering furnace, heated under vacuum conditions, and then ground to obtain a ground powder; the ground powder is etched with a LiF-HCl mixed solution with a mass concentration of 40% to etch the Al layer, and finally, the ground powder is vacuum dried to a water content of not more than 2.5%, thereby obtaining the product.

5. The method of claim 4, wherein the method is characterized by: The average particle size of the M layer element powder and the Al powder is 300-800 mesh.

6. The method of claim 4, wherein the high-entropy two-dimensional transition metal MXene broadband light-absorbing material is prepared by the following steps: The heating condition is 1400-1600 ℃, and the heating time is 10-15 min.

7. The method for preparing a high-entropy two-dimensional transition metal MXene broadband light-absorbing material as described in claim 4, characterized in that: The mass ratio of the LiF-HCl mixed solution to the ground powder is 20-25:

1.

8. The method for preparing a high-entropy two-dimensional transition metal MXene broadband light-absorbing material as described in claim 4, characterized in that: The etching Al layer treatment condition is that the temperature is 40-60 ℃, and the time is 60-72 hours.

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