Method for laser one-step preparation of ultra-small beta-FeOOH nanoparticles

Abstract

The invention discloses a method for preparing ultra-small beta-FeOOH nano-particles by laser in one step, and the ultra-small beta-FeOOH nano-particles which are stable in phase and about 3nm in size are obtained by irradiating block beta-FeOOH in a liquid phase system by pulse laser. In the synthesis process, chemical reagents such as surfactants do not need to be added, the process is simple and convenient, the preparation time is short, the method is green and efficient, and the obtained final product is stable and pure. The ultra-small beta-FeOOH nanoparticles with the size of less than 5nm are expected to play a greater application potential in the fields of catalysis, energy, magnetics, environment, electrochemistry, biology and the like. The method provides a new way for obtaining the ultra-small beta-FeOOH nanoparticles, and expands the new application of the liquid-phase laser processing and preparation technology.

Description

Technical Field

[0001] The invention relates to a technology for preparing stable ultra-small beta-FeOOH nanoparticles, and in particular to a method for preparing ultra-small beta-FeOOH nanoparticles in one step using laser. Background Art

[0002] β-FeOOH, i.e. β-phase iron oxyhydroxide, has a powder color ranging from brown to bright yellow. It is an inorganic iron compound with a tetragonal crystal structure, and its unit cell contains 8 FeOOHs. β-FeOOH has a unique "tunnel-type" structure with 1×1 and 2×2 channels along the

[001] direction, which makes β-FeOOH show a variety of properties and application potentials in magnetism, photocatalysis, environmental governance, electrochemistry and pigments.

[0003] In conventional preparation methods, β-FeOOH is usually obtained by hydrolysis of Fe3+ salt solution containing Cl- or F-. However, due to the excessively fast hydrolysis rate, the final β-FeOOH is often spindle-shaped and large in size (≥500 nanometers), which limits its application in various fields. At present, there are two main methods for preparing smaller-sized β-FeOOH nanoparticles: one is to change the surface tension of the solvent to achieve the purpose of controlling the size of the hydrolyzed β-FeOOH. For example, using an alcohol-water mixed solution as a solvent, the solvothermal method (~100°C, >50min) synthesizes β-FeOOH with a long axis size of tens of nanometers (>20nm). The other is to add a surfactant to limit the hydrolysis growth of β-FeOOH. For example, by adding CTAB, in a 50°C water bath, β-FeOOH nanoparticles with a long axis size of 40-50nm were obtained after tens of hours (>24h). However, the synthesis time of these two methods is long, the steps are relatively cumbersome, and a variety of other chemical reagents are introduced to a greater or lesser extent, making the purification of the final product complicated and inconvenient for subsequent applications. In addition, it is still difficult to obtain ultra-small β-FeOOH non-spindle-shaped nanoparticles with an average particle size below 5nm through these two methods, which cannot fully expose the unique "tunnel-type" structural advantages of β-FeOOH, affecting the practical application of β-FeOOH.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing ultra-small β-FeOOH nanoparticles in one step by laser to solve the above technical problems existing in the prior art.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] The method for preparing ultra-small β-FeOOH nanoparticles in one step by laser of the present invention comprises the following steps:

[0008] First, the β-FeOOH bulk was ultrasonically dispersed in deionized water, and the laser parameters were adjusted to visible light wavelength, energy>50mJ, and frequency>2Hz;

[0009] Ultra-small β-FeOOH nanoparticles can be obtained by continuously irradiating the solution while stirring.

[0010] Compared with the prior art, the method for preparing ultra-small β-FeOOH nanoparticles by laser one-step provided by the present invention uses a laser fragmentation mechanism to directly irradiate the bulk β-FeOOH in the liquid phase system with laser, so as to achieve the purpose of reducing the size of the bulk β-FeOOH, and finally obtain ultra-small β-FeOOH nanoparticles (average particle size of about 3nm) with stable physical phase and good dispersibility. In this process, no surfactant needs to be added, the product is pure, the operation is simple, the preparation time is short, the cost is low, and it is green and efficient. When the laser acts on the bulk β-FeOOH, it will experience a process of rapid temperature increase, and the surface of the block becomes unstable, and cracks and deformation begin to occur. As the temperature accumulates, melting and evaporation phenomena begin to appear on the surface of the bulk β-FeOOH, and plasma plumes containing small clusters and small fragments of β-FeOOH are continuously ejected. After rapid cooling of the liquid phase environment, ultra-small-sized β-FeOOH nanoparticles (average particle size of about 3nm) are finally formed. This method provides new ways and insights for the preparation of ultra-small β-FeOOH nanoparticles, and stimulates the application potential of β-FeOOH in the biological field. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of preparing ultra-small β-FeOOH nanoparticles by laser irradiating bulk β-FeOOH in an embodiment of the present invention;

[0012] Figure 2 The XRD patterns of powder X-ray diffraction of the samples before and after laser treatment: (a) bulk β-FeOOH; (b) ultra-small β-FeOOH nanoparticles;

[0013] Figure 3 (a) is the TEM image of ultrasmall β-FeOOH nanoparticles;

[0014] Figure 3 (b) is the HRTEM image of ultrasmall β-FeOOH nanoparticles;

[0015] Figure 3 (c) is the size distribution diagram of ultrasmall β-FeOOH nanoparticles. DETAILED DESCRIPTION

[0016] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0017] The contents not described in detail in the examples of the present invention belong to the prior art known to professionals in the field. If no specific conditions are specified in the examples of the present invention, the conditions are carried out according to the conventional conditions in the field or the conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used in the examples of the present invention, they are all conventional products that can be purchased commercially.

[0018] The method for preparing ultra-small β-FeOOH nanoparticles in one step by laser of the present invention comprises the following steps:

[0019] First, the β-FeOOH bulk was ultrasonically dispersed in deionized water, and the laser parameters were adjusted to visible light wavelength, energy>50mJ, and frequency>2Hz;

[0020] Ultra-small β-FeOOH nanoparticles can be obtained by continuously irradiating the solution while stirring.

[0021] The solution was continuously irradiated for 9 to 11 min to obtain ultrasmall β-FeOOH nanoparticles with an average particle size of 2.9 to 3.1 nm.

[0022] 1-10 mg of bulk β-FeOOH was ultrasonically dispersed in 10 ml of deionized water.

[0023] All synthetic and preparation processes were carried out at room temperature.

[0024] In summary, the method for preparing ultrasmall β-FeOOH nanoparticles by one step of laser in the embodiment of the present invention uses pulsed laser to irradiate bulk β-FeOOH in a liquid phase system to obtain ultrasmall β-FeOOH nanoparticles with stable phase and size of about 3nm. During the synthesis process, there is no need to add any chemical reagents such as surfactants, the process is simple, the preparation time is short, it is green and efficient, and the final product obtained is stable and pure. Such ultrasmall β-FeOOH nanoparticles with a size of less than 5nm are expected to have greater application potential in the fields of catalysis, energy, magnetism, environment, electrochemistry, biology, etc. This method provides a new way to obtain ultrasmall β-FeOOH nanoparticles and expands new applications of liquid phase laser processing and preparation technology.

[0025] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the embodiments of the present invention are described in detail with specific embodiments below.

[0026] The present invention aims to expand a simple method for rapidly preparing ultra-small β-FeOOH nanoparticles by laser without a surface modifier. When the laser acts on the material system in the liquid medium, a non-equilibrium thermodynamic environment of high temperature, high pressure and high density is instantly generated on the surface of the material, which is helpful to obtain metastable nanomaterials of different sizes and shapes. In particular, when the laser pulse energy exceeds the thermal threshold of the material lattice, the material structure in the liquid phase will be forced to disintegrate and quickly form nanoparticles of smaller size. This phenomenon is called liquid phase laser fragmentation. Using this principle, when the laser beam acts on the bulk β-FeOOH, the material undergoes a rapid temperature rise process, making the surface of the bulk material extremely unstable. With the decrease of surface tension and the increase of thermal expansion force, cracks and deformation begin to appear on the surface of the bulk β-FeOOH. With the further increase of temperature, the surface of the bulk β-FeOOH begins to melt and evaporate, and continuously ejects plasma plumes containing small clusters and small fragments. After rapid cooling in the liquid environment, ultra-small β-FeOOH nanoparticles with an average size of about 3nm are finally formed. During the laser fragmentation process, no additional chemical reagents are added, so no complex by-products are produced, and the final product is pure, green, and efficient. The present invention not only broadens the application of laser preparation technology in liquid phase environment in the synthesis of ultra-small size materials, but also provides new ways and insights for the preparation and application of ultra-small β-FeOOH nanoparticles.

[0027] Example 1

[0028] like Figure 1 , Figure 2 , Figure 3 As shown:

[0029] The specific experimental process is as follows Figure 1 As shown:

[0030] First, a certain amount of bulk β-FeOOH was ultrasonically dispersed into 10 ml of deionized water, and the laser parameters were adjusted to the visible light wavelength, appropriate energy (>50 mJ) and frequency (>2 Hz). The solution was continuously irradiated for 10 minutes while stirring to obtain ultra-small β-FeOOH nanoparticles with an average particle size of about 3 nm. All the synthesis and preparation processes were carried out at room temperature, with mild conditions, simple operation, high synthesis efficiency, green environmental protection, and pure products.

[0031] Figure 2Powder X-ray diffraction (XRD) analysis was performed on the samples before and after laser action. The diffraction peaks of ultra-small β-FeOOH (b) and bulk β-FeOOH (a) nanoparticles are consistent, both corresponding to the standard card JCPDS No. 75-1594 of tetragonal β-FeOOH, indicating that the material phase remains stable during the laser action.

[0032] Figure 3 (a) is a TEM image of ultra-small β-FeOOH nanoparticles, which shows that the size is uniform and the dispersion is good. Figure 3 As shown in (c), it is about 3nm. Figure 3 (b) is the high-resolution lattice fringes of ultrasmall β-FeOOH nanoparticles, whose interplanar spacing is 0.25 nm, corresponding to the (211) plane of tetragonal β-FeOOH.

[0033] Figure 3 :(a) TEM image of ultrasmall β-FeOOH nanoparticles;(b) HRTEM image of ultrasmall β-FeOOH nanoparticles;

[0034] (c) Size distribution of ultrasmall β-FeOOH nanoparticles

[0035] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A method for preparing ultra-small β-FeOOH nanoparticles in one step by laser, characterized in that: Includes steps: First, the β-FeOOH bulk was ultrasonically dispersed in deionized water, and the laser parameters were adjusted to visible light wavelength, energy>50mJ, and frequency>2Hz; Ultra-small β-FeOOH nanoparticles can be obtained by continuously irradiating the solution while stirring.

2. The method for preparing ultra-small β-FeOOH nanoparticles by one step of laser according to claim 1, characterized in that: The solution was continuously irradiated for 9 to 11 min to obtain ultrasmall β-FeOOH nanoparticles with an average particle size of 2.9 to 3.1 nm.

3. The method for preparing ultra-small β-FeOOH nanoparticles by one step of laser according to claim 2, characterized in that: 1-10 mg of bulk β-FeOOH was ultrasonically dispersed in 10 ml of deionized water.

4. The method for preparing ultra-small β-FeOOH nanoparticles by one step of laser according to claim 1, 2 or 3, characterized in that: All synthetic and preparation processes were carried out at room temperature.

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