High-entropy two-dimensional transition metal MXene wide-band light-absorbing material and preparation method thereof

Abstract

The present application relates to a kind of high-entropy two-dimensional transition metal MXene wide-band light-absorbing material, the material is made of M layer element, A layer element and graphite powder, and two-dimensional layered structure is formed by etching A layer Al element with 40% mass concentration LiF-HCl mixed solution, and its chemical general formula is M3C2;Wherein: M layer element is any five kinds of metal elements in Ti, Zr, Nb, Mo, Hf and W, and metal atom is equimolar ratio;A layer element is Al.Meanwhile, the present application also provides the preparation method of the material.The preparation method of the present application is easy, strong repeatability, high production efficiency, can be used for industrial mass production, and the prepared wide-band light-absorbing material has solar energy absorption rate of 0.891~0.910 in 0.3~2.5 μm wave band range, and can be widely applied to solar light-heat conversion material.

Description

Technical Field

[0001] This invention relates to a light-absorbing material, and more particularly to a high-entropy two-dimensional transition metal MXene broadband light-absorbing material and its preparation method. Background Technology

[0002] With the advancement of the "dual carbon" goal and the global energy structure transformation, the large-scale utilization of solar energy as a clean and renewable energy source has become a key direction. Among them, solar thermal conversion technology, due to its high energy storage density and wide range of applications (such as solar thermal power generation, seawater desalination, and industrial waste heat recovery), has become one of the core pathways for solar energy utilization. As the "core engine" of the solar thermal conversion system, the absorption capacity of light-absorbing materials 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 absorptivity (α) in the 0.3~2.5 μm wide band needs to reach above 0.95 to meet the practical requirements of efficient solar thermal utilization. The essence of light absorption is that photon energy drives electron transitions, and the electronic structure of the material (such as band gap width and electronic state density near the Fermi level) is the core factor determining absorption performance. Currently, mainstream light-absorbing materials are mainly divided into three categories, but all have significant limitations:

[0003] Traditional metal-based materials (such as Au, Ag nanoparticles, Mo, and W thin films) achieve light absorption through localized surface plasmon resonance (LSPR) of metal d electrons or d-band transitions. However, the LSPR effect is concentrated in a specific narrow wavelength band (e.g., the absorption peak of Au nanoparticles is around 520 nm), and metal thin films have high reflectivity in the near-infrared region (e.g., the reflectivity of Mo thin films is >30% in the 1.5 μm band), failing to cover the entire solar spectrum. Semiconductor-based materials (such as TiO2, Si, and CuInGaSe2) absorb photons through valence band-conduction band electron transitions, but their band gap width is fixed (e.g., anatase TiO2 has a band gap of 3.2 eV, absorbing only <387 nm ultraviolet light; single-crystal silicon has a band gap of 1.12 eV, with an absorption cutoff wavelength of approximately 1100 nm), resulting in poor absorption capacity in the near-infrared region. Furthermore, most semiconductors are prone to crystal transformation at high temperatures (e.g., TiO2 at 600°C). Above ℃, it transforms into the rutile phase, and its absorption performance decreases by 40%; carbon-based materials (such as graphene, carbon nanotubes, and mesoporous carbon) achieve broadband absorption through their conjugated π-electron system, but they have poor chemical stability—they are easily oxidized to CO2 in air environments above 200℃, and the bonding force between carbon-based materials and the substrate is weak, making them easy to peel off during thermal cycling, and their service life is usually less than 1000 hours.

[0004] To overcome the limitations of traditional materials, high-entropy materials, due to their characteristic of "multi-principal element synergistic regulation of electronic structure," have become a research hotspot in broadband light-absorbing materials. High-entropy materials (such as high-entropy oxides, high-entropy sulfides, and high-entropy MXenes) can achieve a continuous distribution of electronic state density near the Fermi level through the entropy increase effect of multiple metal elements, theoretically covering the electronic transition requirements of the entire solar spectrum. For example, (CoNiCuZnMn)O prepared by Zhang et al. 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 band, but due to the disordered valence state of metal ions leading to the disordered expansion of the band gap, the absorption efficiency in the near-infrared region (1.5–2.5 μm) is still below 60%. The high-entropy sulfide (MoNbTaWTi)S2 developed by Li's team (ACS Applied Materials & Interfaces, 2023, 15: 28761) improves visible light absorption through the hybridization of sp orbitals and metal-d orbitals, but the sulfide is prone to hydrolysis (absorption rate decreases by 25% within 30 days in an environment with humidity > 60%), and it is also prone to decomposition at high temperatures (> 150 °C) to produce toxic gases, which limits its practical application.

[0005] Currently, with the development of science and technology, there is an urgent need for broadband light-absorbing materials. While MXene materials show promise, traditional monocomponents suffer from impedance mismatch and a single loss mechanism. High-entropy strategies, however, can regulate the conductivity and polarization loss of materials. Therefore, the fabrication of high-entropy MXene broadband light-absorbing materials holds promise for solving existing problems and achieving breakthroughs in optoelectronics, electromagnetic management, and other fields. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a high-performance, high-entropy, two-dimensional transition metal MXene broadband light-absorbing material.

[0007] Another technical problem to be solved by the present invention is to provide a method for preparing the high-entropy two-dimensional transition metal MXene broadband light-absorbing material.

[0008] To address the aforementioned problems, the present invention provides 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 the A-layer Al elements are etched with a 40% LiF-HCl mixed solution to form a two-dimensional layered structure, with the general chemical formula 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; the A-layer element is Al.

[0009] The 40% LiF-HCl mixed solution refers to the mixture obtained by dissolving LiF powder in concentrated HCl.

[0010] The material exhibits a solar energy absorption rate of 0.891–0.910 in the 0.3–2.5 μm wavelength range.

[0011] The preparation method of the high-entropy two-dimensional transition metal MXene broadband light-absorbing material described above is characterized by: firstly, mixing 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 equimolar ratio; and then mixing the mixture with anhydrous ethanol as the medium at 580 r / min. -1 The mixture is ball-milled for 12-24 hours to obtain a uniformly mixed powder. Then, the mixed powder is transferred to a spark plasma sintering furnace, heated under vacuum conditions, and then ground to obtain the ground powder. The ground powder is then etched with a 40% LiF-HCl mixed solution to etch the Al layer. Finally, it is ground and vacuum dried until the water content is no more than 2.5%.

[0012] The average particle size of the M-layer element powder and the Al powder is 300~800 mesh.

[0013] The heating conditions are 1400~1600 ℃, and the heating time is 10~15 min.

[0014] The mass ratio of the LiF-HCl mixed solution to the ground powder is 20~25:1.

[0015] The conditions for etching the Al layer are a temperature of 40~60 ℃ and a time of 60~72 hours.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. Considering that different metals exhibit strong interband transitions only in specific spectral ranges due to their electronic structures, which is not conducive to the absorption of the entire solar spectrum, this invention uses an equimolar ratio of Ti, Zr, Nb, Mo, Hf and W to form a high-entropy MXene. By combining multiple metals to fill the d-band distribution near the Fermi level, the absorption and utilization of the entire solar spectrum can be achieved.

[0018] 2. This invention uses spark plasma sintering (SPS) to prepare high-entropy MXene layered structures: spark plasma sintering (SPS) has a fast heating time, low temperature and energy saving, high product purity and excellent performance, and the process is controllable.

[0019] 3. The equipment required for this invention is simple, the preparation method is easy, the repeatability is strong, and the production efficiency is high, so it can be used for large-scale industrial production.

[0020] 4. The broadband light-absorbing material prepared by this invention has a solar energy absorption rate of 0.891~0.910 in the 0.3~2.5 μm wavelength range, and can be widely used in solar thermal conversion materials. Attached Figure Description

[0021] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0022] Figure 1 The image shows the XRD pattern of the (TiZrNbMoHf)3C2 broadband light-absorbing material powder of Example 1 of this invention.

[0023] Figure 2 The absorption spectrum (0.3~2.5 μm) of the (TiZrNbMoHf)3C2 broadband light-absorbing material powder in Example 1 of this invention.

[0024] Figure 3 The absorption spectrum (0.3~2.5 μm) of the (TiZrNbMoHf)3C2 broadband light-absorbing material powder in Example 1 of this invention. Detailed Implementation

[0025] A high-entropy two-dimensional transition metal MXene broadband light-absorbing material is disclosed. The material consists of M-layer elements, A-layer elements, and graphite powder. The A-layer Al element is etched with a 40% LiF-HCl mixed solution to form a two-dimensional layered structure. Its general chemical formula is M3C2. 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. The A-layer element is Al.

[0026] Among them, the LiF-HCl mixed solution with a mass concentration of 40% refers to the mixed solution obtained by dissolving LiF powder in concentrated HCl.

[0027] The material exhibits a solar energy absorption rate of 0.891–0.910 in the 0.3–2.5 μm wavelength range.

[0028] A method for preparing a high-entropy two-dimensional transition metal MXene broadband light-absorbing material: 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, with equimolar ratios of metal atoms. The average particle size of the M-layer element powder and Al powder is 300~800 mesh. The mixture is then heated at 580 rpm using anhydrous ethanol as the medium. -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%.

[0029] Example 1:

[0030] 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.

[0031] 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.

[0032] The light absorption properties of the obtained (TiZrNbMoHf)3C2 light-absorbing material were evaluated:

[0033] 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.

[0034] The results are obvious. Figure 2 , Figure 3 As shown, the (TiZrNbMoHf)3C2 light-absorbing material has a solar energy absorption rate of 0.891~0.909 in the 0.3~2.5μm wavelength range.

[0035] Example 2:

[0036] First, the M-layer element powder, Al powder, and graphite powder were mixed in a 3:1:1 molar ratio. The M-layer element powder refers to Ti, Zr, Nb, Mo, and W, 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 24 hours to obtain a homogeneous powder. Then, the powder was transferred to a spark plasma sintering furnace and heated at 1500℃ for 13 minutes under vacuum. After grinding, the powder was further ground. The ground powder was then used to etch an Al layer with a 40% (w / w) LiF-HCl solution at 50℃ for 66 hours. The mass ratio (g / g) of the LiF-HCl solution to the ground powder was 20:1. Finally, the mixture was ground and vacuum-dried until the moisture content was no more than 2.5%, yielding the (TiZrNbMoW)3C2 light-absorbing material.

[0037] The light absorption properties of the obtained (TiZrNbMoW)3C2 light-absorbing material were evaluated:

[0038] The testing method and the amount of test sample used are the same as in Example 1.

[0039] The results show that the (TiZrNbMoW)3C2 light-absorbing material has a solar energy absorption rate of 0.892~0.910 in the 0.3~2.5μm wavelength range.

[0040] Example 3:

[0041] First, the M-layer element powder, Al powder, and graphite powder were mixed in a 5:1:1 molar ratio. The M-layer element powder refers to Ti, Zr, Nb, W, 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. -1The mixture was ball-milled for 24 hours to obtain a homogeneous powder. Then, the powder was transferred to a spark plasma sintering furnace and heated at 1600 °C for 15 min under vacuum. After grinding, the powder was further ground. The ground powder was then used to etch an Al layer with a 40% (w / w) LiF-HCl solution at 60 °C for 72 hours. The mass ratio (g / g) of the LiF-HCl solution to the ground powder was 22:1. Finally, the mixture was ground and vacuum-dried until the moisture content was no more than 2.5%, yielding the (TiZrNbWHf)3C2 light-absorbing material.

[0042] The light absorption properties of the obtained (TiZrNbWHf)3C2 light-absorbing material were evaluated:

[0043] The testing method and the amount of test sample used are the same as in Example 1.

[0044] The results show that the (TiZrNbWHf)3C2 light-absorbing material has a solar energy absorption rate of 0.891 to 0.908 in the 0.3 to 2.5 μm wavelength range.

[0045] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-entropy two-dimensional transition metal MXene broadband light-absorbing material, characterized in that: This material consists of an M-layer element, an A-layer element, and graphite powder. The A-layer Al element is etched with a 40% LiF-HCl mixed solution to form a two-dimensional layered structure, with the general chemical formula M3C2. The M-layer element is any five metal elements selected from Ti, Zr, Nb, Mo, Hf, and W, with an equimolar ratio of metal atoms. The A-layer element is Al. The 40% LiF-HCl mixed solution refers to a mixture obtained by dissolving LiF powder in concentrated HCl. The solar energy absorption rate of this material in the 0.3–2.5 μm wavelength range is 0.891–0.

910.

2. The method for preparing a high-entropy two-dimensional transition metal MXene broadband light-absorbing material as described in claim 1, characterized in that: First, mix the M-layer element powder, Al powder, and graphite powder 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, with the metal atoms in equimolar proportions. Use anhydrous ethanol as the medium at 580 r / min. -1 The mixture is ball-milled for 12-24 hours to obtain a uniformly mixed powder. Then, the mixed powder is transferred to a spark plasma sintering furnace, heated under vacuum conditions, and then ground to obtain the ground powder. The ground powder is then etched with a 40% LiF-HCl mixed solution to etch the Al layer. Finally, it is ground and vacuum dried until the water content is no more than 2.5%.

3. The method for preparing a high-entropy two-dimensional transition metal MXene broadband light-absorbing material as described in claim 2, characterized in that: The average particle size of the M-layer element powder and the Al powder is 300~800 mesh.

4. The method for preparing a high-entropy two-dimensional transition metal MXene broadband light-absorbing material as described in claim 2, characterized in that: The heating conditions are 1400~1600 ℃, and the heating time is 10~15 min.

5. The method for preparing a high-entropy two-dimensional transition metal MXene broadband light-absorbing material as described in claim 2, characterized in that: The mass ratio of the LiF-HCl mixed solution to the ground powder is 20~25:

1.

6. The method for preparing a high-entropy two-dimensional transition metal MXene broadband light-absorbing material as described in claim 2, characterized in that: The conditions for etching the Al layer are a temperature of 40~60 ℃ and a time of 60~72 hours.

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