A TiC material capable of absorbing light across the entire solar spectrum x O 1-x Powders and their preparation methods

Abstract

The application discloses a kind of high-efficiency light-absorbing materials TiC x O 1‑x And preparation method, with Ti element MAX phase powder, by plasma treatment, high-temperature oxidation step under low-oxygen environment is obtained.The high-efficiency light-absorbing materials TiC x O 1‑x In the preparation process, by controlling the oxygen content by regulating gas pressure value, realize the control of TiC x O 1‑x Light-absorbing performance.The TiC x O 1‑x Metal oxide light-absorbing capacity is strong, can satisfy relevant photo-thermal application demand, and preparation method is more existing carbon reduction method production TiC x O 1‑x Efficiency is higher, the oxygen content of product TiC x O 1‑x Can be accurately regulated, and preparation process is environment-friendly, pollution-free.

Description

Technical Field

[0001] This invention relates to the field of light absorption, specifically to a TiC with controllable oxygen content. x O 1-x Preparation methods and applications of powders. Background technology: Due to the surging demand for freshwater from a continuously growing global population, water pollution caused by human industrialization and activities, extreme weather events triggered by global climate change (such as intensified droughts and altered precipitation patterns), and the effects of glacial melting, global freshwater resources are facing scarcity (Reference: Elsaid K et al. [J]. Science of the Total Environment, 2020, 748141528-141528). However, seawater, which accounts for 97% of the Earth's total water, cannot be directly used for drinking, domestic washing, and most industrial production processes due to its high concentration of salt, minerals, and other impurities. Therefore, how to solve the problem of freshwater scarcity through seawater desalination has become one of the most urgent problems facing the world.

[0002] Solar energy, as one of the most promising sustainable energy sources, has attracted widespread attention both domestically and internationally in the thermal desalination process, where solar energy is the sole energy source. This technology, which utilizes solar energy as its primary energy source, is characterized by its pollution-free, energy-efficient, and easy-to-deploy nature. In this desalination technology, solar energy radiates across the entire spectrum in the form of electromagnetic waves, emitting ultraviolet (UV), visible, and infrared (IR) light carrying photons with different vibration frequencies. The process by which these photons are absorbed by specific materials and converted into heat energy is called photothermal conversion (Reference: Sharon H et al. [J]. Renewable and Sustainable Energy Reviews, 2015, 41(Jan.): 1080-1118). Therefore, how to efficiently capture full-spectrum energy is a major challenge in solar photothermal conversion and also one of the important criteria for evaluating the performance of materials in absorbing solar energy and performing photothermal conversion.

[0003] TiO2, a common photothermal material, exhibits excellent light absorption in the ultraviolet band (200nm-400nm). However, its light absorption significantly decreases in the infrared and visible light bands beyond 400nm, which is the main reason limiting its application in practical production. Existing research indicates that Moharana et al. synthesized titanium oxide carbides (TiC) using 3.15% carbon-doped TiO2. x O 1-xBecause carbon introduces a new energy level near the top of the valence band, the band gap of TiO2 is effectively reduced by 0.3 eV, thereby improving its visible light absorption performance (Reference: PK. Moharana et al., J. New Journal of Chemistry, 2025, 49(34): 14638-14645.). However, the preparation of TiC... x O 1-x The main method is carbon reduction. The specific process of carbon reduction is as follows: Titanium dioxide (TiO2, 98.6% by mass) is used as the raw material, and charcoal (C, 89% by mass) is used as the reducing agent. Titanium dioxide and charcoal, mixed in a certain molar ratio, are ground in a planetary ball mill at a speed of 100-400 r / min for 6-10 hours. The mixed powder is then uniaxially pressed into blocks in a hardened steel mold at a pressure of 4-6 MPa. These blocks are then placed in a crucible and placed in a vacuum furnace. At a system pressure of 50 Pa, the raw material is heated to different reaction temperatures at a heating rate of 10 °C / min and maintained for 4 hours. Afterwards, when the product cools to 200 °C, the power to the vacuum furnace is cut off, yielding the reduced product TiC. x O 1-x (Reference: Sen W et al. [J]. International Journal of Refractory Metals and HardMaterials, 2010, 28(5): 628-632). However, using this method to prepare TiC... x O 1-x The yield was low, and there was a high amount of intermediate phase (Ti) during the reduction process. n O 2n-1 (e.g., Ti2O3), making it impossible to precisely control the oxygen content of the product. Summary of the Invention: The purpose of this invention is to provide a method for preparing and applying highly efficient light-absorbing metal oxides. The preparation method of this invention is characterized by a preparation efficiency far exceeding that of the carbon reduction method, and the ability to precisely control the oxygen content of the product.

[0004] The objective of this invention is achieved through the following technical solution: A method for preparing a highly efficient light-absorbing metal oxide includes the following steps: Ti-containing MAX phase powder is subjected to plasma treatment, followed by high-temperature oxidation treatment to create a low-oxygen environment by controlling the gas pressure to obtain oxygen-deficient TiC. x O 1-x The metal oxides are the high-efficiency light-absorbing metal oxides.

[0005] Furthermore, the Ti-containing MAX phase is any one of Ti2AlC, Ti3AlC2, and Ti2AlN.

[0006] Furthermore, the particle size of the Ti-containing MAX phase powder is 15 μm-200 μm, and the purity is higher than 99%.

[0007] Furthermore, the MAX phase powder is subjected to plasma treatment, and the process parameters for the plasma treatment are as follows: Main gas type and flow rate: Ar 50 L / min Auxiliary gas type and flow rate: H2 5-20 L / min, N2 0-5 L / min Current: 420A Voltage: 60V Furthermore, the experimental amount of powder was placed in a closed tube furnace at an experimental safe pressure (80000 Pa), and the pressure was gradually reduced to create a low-oxygen environment. The powder mass was calculated as follows (e.g., Ti). x Al y E z Where E is C or N, and satisfies x = y + z): Decomposition reaction equation: Ti x Al y E z → z TiE+yTiAl The oxidation reaction equation for Ti₂AlC is: 4TiAl + 4TiC + 15O₂ → 8TiO₂ + 2Al₂O₃ + 4CO₂ The oxidation reaction equation for Ti₂AlC is: 8TiC + 4TiAl + 23O₂ → 12TiO₂ + 2Al₂O₃ + 8CO₂ The oxidation reaction equation for Ti₂AlN is: 4TiN + 4TiAl + 11O₂ → 8TiO₂ + 2Al₂O₃ + 2N₂ Number of moles of oxygen:

[0008] The mass of TiC and TiAl completely oxidized: m(TiE, TiAl) = M(TiE, TiAl) × A × n(O2) / C (A and C are the coefficients of TiE and TiAl in the oxidation reaction, and their specific values ​​depend on the oxidation reaction equation.) Pressure range: 100Pa-80000Pa Furthermore, the powder after plasma spraying undergoes high-temperature oxidation treatment. The parameters for this high-temperature oxidation treatment are as follows: Main air type and pressure: 1×10 4 Pa Heating rate: 5℃ / min Upper limit of temperature rise: 900℃-1000℃ Insulation time: 12 hours Cooling method: Natural cooling A TiC with controllable oxygen content x O 1-X The application of powder, namely TiC x O 1-X The powder was prepared by the above-described method.

[0009] The embodiments of the present invention have the following gain effects: The plasma spraying and high-temperature oxidation preparation method proposed in this invention, operating under low oxygen conditions, offers significantly higher preparation efficiency compared to existing carbon reduction methods. Furthermore, it eliminates the intermediate phase and allows for the preparation of TiC products. x O 1-X The oxygen content in the system is precisely controlled. Attached image description: Figure 1 An oxygen-controllable TiC according to Example 1 of the present invention x O 1-X The light absorption diagram, with the gray background representing the solar spectrum; Figure 2 The oxygen content controllable TiC of Example 1 of the present invention x O 1-X XRD; Figure 3 SEM images of the partial dissociation microstructure of Ti2AlC powder under different gas pressures in Example 1 of this invention: (a) 0.1 atm; (b) 0.4 atm Detailed implementation method: To make the objectives, technical solutions, and advantages of the embodiments clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially. The technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings.

[0010] Example 1 A high-efficiency photothermal conversion material TiC x O 1-X The preparation of [the substance] specifically includes the following steps: 1000g of raw Ti2AlC powder was subjected to plasma treatment with the following process parameters: Main gas type and flow rate: Ar 50 L / min Auxiliary gas type and flow rate: H2 5-20 L / min, N2 0-5 L / min Current: 420A Voltage: 60V Furthermore, the experimental powder was placed in a closed tube furnace at an experimental safe pressure (80000 Pa), and the pressure was gradually reduced to create a low-oxygen environment. The mass of the experimental powder was calculated as follows. Decomposition reaction equation: Ti₂AlC → TiC + TiAl Oxidation reaction equation: 4TiAl + 4TiC + 15O2 → 8TiO2 + 2Al2O3 + 4CO2 Quartz tube dimensions: Length 60cm; Diameter 5cm Quartz tube volume: V=πr 2 h≈0.001178m 3 Number of moles of oxygen:

[0011] Number of moles of TiC and TiAl: n(TiC, TiAl) = 4 × n(O2) / 15 = 2.13 × 10 -3 mol Molar amounts of TiC and TiAl: 134.73 g / mol The mass of TiC and TiAl completely oxidized: m(TiC, TiAl) = 134.73 × n(TiC, TiAl) = 0.28 g Furthermore, 0.28g of the plasma-treated powder was placed in a tube furnace for low-oxygen environment treatment. The operation steps were as follows: the tube furnace was evacuated using a vacuum pump. The experiment was divided into 4 groups. The gas pressure inside the furnace was measured to be 0.8atm, 0.4atm, 0.1atm, and 0.01atm respectively using a Pirani standard tube (vacuum gauge). The tube furnace was then sealed.

[0012] Furthermore, the powder undergoes high-temperature oxidation treatment, with the following process parameters: Main air type and pressure: 1×10 4 Pa Heating rate: 5℃ / min Maximum temperature rise: 900℃ Insulation time: 12 hours Cooling method: Natural cooling Finally, TiC with high photothermal performance was obtained. x O 1-X Powder. For example... Figure 1 As shown, the average light absorptivity of the powder obtained after plasma treatment and high-temperature oxidation treatment gradually increases with decreasing air pressure, reaching a maximum of 93.38% (0.1 atm). The calculation method is as follows:

[0013] In the formula —The monochromatic absorption ratio of the object; Solar monochromatic radiance.

[0014] TiC x O 1-X It is an intermediate phase between TiC and TiO2, with the same crystal structure as TiC, but due to the doping of the O element, TiC... x O 1-X The diffraction peaks of TiC are shifted at a small angle relative to TiC, such as... Figure 2 As shown. Furthermore, it is highly sensitive to oxygen content; when the pressure exceeds 0.4 atm, TiC... x O 1-X It will oxidize to TiO2, such as Figure 3 As shown.

[0015] This invention creatively proposes to introduce oxygen vacancies into Ti2AlC powder through high-temperature oxidation by controlling oxygen content, successfully developing a TiC powder with strong light absorption. x O 1-X Metal oxides, and the preparation method is more efficient than the existing carbon reduction method, and has a better effect on the product TiC. x O 1-X The oxygen content can be precisely controlled, and the preparation process is environmentally friendly and pollution-free.

[0016] Finally, it should be noted that although the present invention and its advantages have been described in detail above, it should be understood that various changes, substitutions, and modifications can be made without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the invention is not limited to the specific embodiments of the processes, apparatus, means, methods, and steps described in the specification. Those skilled in the art will readily understand from the disclosure of this invention that existing and future processes, apparatus, means, methods, or steps that perform substantially the same function or obtain substantially the same results as the corresponding embodiments described herein can be used according to the present invention. Therefore, the appended claims are intended to include such processes, apparatus, means, methods, or steps within their scope.

Claims

1. A TiC with controllable oxygen content x O 1-x The method for preparing powder is characterized by, Includes the following steps: (1) Plasma treatment of Ti-containing MAX phase powder; (2) The mass of the plasma-treated MAX phase material was placed in a closed tube furnace with an experimental safety pressure of 80,000 Pa. The mass of the powder was calculated as follows: Decomposition reaction equation: Ti x Al y E z → z TiE+yTiAl The oxidation reaction equation for Ti₂AlC is: 4TiAl + 4TiC + 15O₂ → 8TiO₂ + 2Al₂O₃ + 4CO₂ The oxidation reaction equation for Ti₂AlC is: 8TiC + 4TiAl + 23O₂ → 12TiO₂ + 2Al₂O₃ + 8CO₂ The oxidation reaction equation for Ti₂AlN is: 4TiN + 4TiAl + 11O₂ → 8TiO₂ + 2Al₂O₃ + 2N₂ Number of oxygen moles: n = PV / RT * 0.21 The mass of TiC and TiAl completely oxidized: m = M × A × n / C, where A and C are the coefficient combination of TiE and TiAl in the oxidation reaction, and Ti... x Al y E z In this case, E is either C or N, and satisfies x = y + z, the specific value of which depends on the oxidation reaction equation; (3) Use a vacuum pump to gradually reduce the gas pressure inside the closed tube furnace to 100 Pa, 1000 Pa, 10000 Pa, 40000 Pa, and 80000 Pa to create a low-oxygen environment; (4) High-temperature oxidation treatment is carried out in the low-oxygen environment to obtain TiC with controllable oxygen content. x O 1-x Powder.

2. The preparation method according to claim 1, characterized in that, The Ti-containing MAX phase is either Ti2AlC or Ti3AlC2.

3. The preparation method according to claim 1, characterized in that, The Ti-containing MAX phase powder has a particle size of 15 μm-200 μm and a purity of over 99%.

4. The preparation method according to claim 1, characterized in that, The MAX phase powder is subjected to plasma treatment, and the process parameters of the plasma treatment are as follows: Main gas type and flow rate: Ar 50 L / min Auxiliary gas type and flow rate: H2 5-20 L / min, N2 0-5 L / min Current: 420 A Voltage: 60 V.

5. The preparation method according to claim 1, characterized in that, The process parameters for the high-temperature oxidation treatment are as follows: Main air type and pressure: 1×10 4 Pa Heating rate: 5℃ / min Upper limit of temperature rise: 900℃-1000℃ Insulation time: 12 hours Cooling method: Natural cooling.

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