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A method for preparing porous silicon by magnesia thermal reduction

A technology of porous silicon and magnesium heating, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the limitations of large-scale commercial application of porous silicon, the difficulty of mass preparation of porous silicon powder, and the limited thickness of porous silicon films, etc. problem, to achieve the effect of low cost, environmental friendliness and high luminous efficiency

Inactive Publication Date: 2011-11-30
TONGJI UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the thickness of the porous silicon film prepared by this method is limited, the mechanical strength is low, the pore size distribution is uneven, and the cost of raw materials is high, which is harmful to the environment.
In addition, due to the process limitations of this method, the products mostly appear in the form of porous silicon films, and it is often difficult to prepare a large amount of porous silicon powder, thus limiting the large-scale commercial application of porous silicon

Method used

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  • A method for preparing porous silicon by magnesia thermal reduction
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  • A method for preparing porous silicon by magnesia thermal reduction

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Embodiment 1

[0019] (1) At room temperature, SiO powder and magnesium powder were uniformly mixed in a molar ratio of 1:1 under the protection of argon, then placed in a tubular atmosphere furnace, heated to 500°C in an argon flow, and reacted at a constant temperature for 6 hours, and then naturally Cool to room temperature;

[0020] (2) Soak the obtained product in hydrochloric acid with a concentration of 0.1 mol / L for 24 hours, remove magnesium oxide, and obtain a solid product after filtration, then fully wash with deionized water, then fully wash with absolute ethanol, and dry Afterwards, porous silicon powder is obtained. Its specific surface area is about 200 m 2 / g, the porosity is above 90%. Its microstructure and phase analysis are as follows figure 1 with figure 2 shown. from figure 1 It can be seen that the product has a nanoporous structure with a uniform pore size distribution. from figure 2 According to the XRD diffraction spectrum analysis of the material, the pr...

Embodiment 2

[0022] (1) SiO at room temperature 0.5 The powder and magnesium powder are evenly mixed at a molar ratio of 1:0.5 under the protection of argon, then placed in a tube-type atmosphere furnace, heated to 450°C in an argon flow, and reacted at a constant temperature for 12 hours, and then naturally cooled to room temperature;

[0023] (2) Soak the obtained product in an ethanol solution of hydrochloric acid with a concentration of 6 mol / L for 0.5 hours, remove magnesium oxide, and obtain a solid product after filtration, then fully wash it with deionized water, and then fully wash it with anhydrous ethanol Porous silicon powder is obtained after washing and drying. Its specific surface area is about 210 m 2 / g, the porosity is above 90%.

Embodiment 3

[0025] (1) At room temperature, SiO powder and magnesium powder were uniformly mixed at a molar ratio of 1:1.5 under the protection of argon, then placed in a tube-type atmosphere furnace, heated to 600°C in an argon flow, and reacted at a constant temperature for 4 hours, and then naturally Cool to room temperature;

[0026] (2) Soak the obtained product in dilute sulfuric acid with a concentration of 0.1 mol / L for 24 hours, remove magnesium oxide, and obtain a solid product after filtration, then fully wash with deionized water, then fully wash with acetone, and dry Porous silicon powder is obtained. Its specific surface area is about 180 m 2 / g, the porosity is about 80%.

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Abstract

The invention belongs to the synthesis field of porous silicon materials, and particularly relates to a method for preparing porous silicon by magnesiothermic reduction. The method comprises the following steps: carrying out magnesiothermic reduction reaction based on silicon oxide SiOx (x = 0.5-2) as a raw material to generate a mixture of silicon and magnesium oxide; and then selectively dissolving away magnesium oxide with an acid so as to ultimately obtain a self-supported porous silicon material. Compared with the previous conventional electrochemical anodic etching methods, the method provided by the invention has the advantages that the use of expensive monocrystal silicon wafers is avoided, but simple, easily available and low-cost silicon oxide is used as the raw material, thereby not only reducing the cost but also increasing the yield; and the method has the advantages of simple preparation process, environmental friendliness, high preparation efficiency and good repeatability, is more suitable for industrial production, and is expected to be widely applied in the fields of lithium ion secondary batteries, optical materials, biomedical devices, gas-sensitive devices, etc.

Description

technical field [0001] The invention belongs to the field of preparation of inorganic nanoporous materials, in particular to a method for preparing porous silicon by magnesia thermal reduction. Background technique [0002] As early as 1956, A. Uhlir Jr. and I. Uhlir of Bell Laboratories in the United States discovered that porous silicon could be formed by electrochemical corrosion of crystalline silicon in hydrofluoric acid. Until 1990, L. T. Canham of the British National Defense Research Institute further corroded porous silicon in hydrofluoric acid solution, and observed the remarkable visible light photoluminescence phenomenon at room temperature for the first time, which aroused extensive attention of researchers at home and abroad, thus opening up the A new field of research on silicon-based luminescent materials. As a new type of semiconductor material, porous silicon has the advantages of large specific surface area, high biological activity and unique photoelectr...

Claims

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Application Information

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IPC IPC(8): C01B33/023
Inventor 包志豪陈珂
Owner TONGJI UNIV
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