CN106830059A - A kind of preparation method of dendritic hierarchy tin ash - Google Patents

Abstract

The invention relates to a preparation method of dendrite-structured tin dioxide used for moisture-sensitive device materials, and belongs to the technical field of preparation technology and application of advanced nanometer functional materials. It is characterized in that tin tetrachloride (pentahydrate) is used as a reaction raw material, urea is used as an alkali source, polyethylene glycol 6000 is used as a surfactant, and deionized water is used as a dispersant, and the product having a dendritic structure is obtained through hydrothermal reaction. Tin oxide nanomaterials. Based on the AC impedance diagrams of the dendritic structure SnO ₂ sensitive element with interdigitated electrodes measured under different relative humidity conditions, it can be seen that with the increase of humidity, the measured impedance value decreases sharply, showing a good performance. humidity sensitivity properties.

Description

A kind of preparation method of dendritic hierarchical structure tin dioxide

technical field

The invention relates to a preparation method of dendrite-structured tin dioxide used for moisture-sensitive device materials, and belongs to the technical field of preparation technology and application of advanced nanometer functional materials.

Background technique

Tin dioxide (SnO ₂ ) is a new wide bandgap n-type semiconductor material with a bandgap width of 3.6eV. It has the advantages of abundant raw materials, low cost, environmental friendliness and no pollution. Due to the special small size effect and surface effect of the hierarchical structure tin oxide, it has broad application prospects in the fields of sensors, quantum size semiconductors, photocatalysis, and solar cells. Hierarchical structure is a morphological structure composed of low-dimensional structural units (such as granular, rod-shaped, flower-shaped, spherical, tubular, array-shaped, etc.). The assembly and arrangement of low-dimensional structural units can be lattice fusion or chemical bond. The effect can also be an orderly arrangement of intermolecular forces, electrostatic or magnetic field interactions. The hierarchical structure characteristics determine that it has high porosity, high specific surface area, better surface adsorption, better surface activity, and a larger contact area with the corresponding reaction medium (gas, light, dye, etc.), making it in the It has excellent potential applications in chemical sensors and photocatalysis. Hierarchical structure SnO ₂ is widely used in various fields as a new type of functional material. At the same time, the special structure of hierarchical structure SnO ₂ is a key factor that significantly affects the performance and application of micro-nano materials, so it has attracted extensive attention from researchers at home and abroad. , the research on the preparation of hierarchical structure SnO ₂ materials and related properties has become a hot spot. The morphology and structure of hierarchical SnO ₂ functional materials are important factors affecting their gas-sensing properties. More and more researchers are working on controlling the synthesis of hierarchical SnO ₂ with special morphology to improve the sensitivity of the material itself. In recent years, there have been many synthetic methods to prepare hierarchical structure SnO ₂ , but many preparation processes still have defects and deficiencies. At present, the methods for preparing tin oxide with hierarchical structure can be mainly divided into solid-phase method, liquid-phase method, gas-phase method, etc. The more commonly used methods include hydrothermal method, sol-gel method, microemulsion method, chemical precipitation method, supercritical fluid method, etc. drying method and microwave method and so on. At present, there are many patents on the preparation method of hierarchical structure tin dioxide, but the existing methods still have problems such as complicated process, high energy consumption, high cost, and the preparation method is not environmentally friendly. For example, Chinese patent CN104891557A discloses a method for preparing tin dioxide nanoflowers with a hollow structure. In this method, tin tetrachloride is used as a tin source and zinc oxide is an auxiliary material. Annealing, then adding nitric acid and standing still to obtain hollow structure nanoflowers, this method has high cost and high energy consumption, and the use of nitric acid in the process has potential safety hazards. Chinese patent CN105152202A discloses a synthesis method of antimony-doped spherical tin dioxide, using stannous chloride as the tin source, doping with antimony trichloride, sodium hydroxide as the precipitating agent, cetyl trimethyl bromide Ammonium chloride is used as a surfactant. After hydrothermal reaction for 16-24 hours, the product is dried at 60°C for 24 hours, and then heat-treated at 500°C for 3 hours to obtain the target product. This synthesis method has a long preparation period and is cumbersome. High temperature calcination, relatively high energy consumption.

In this project, SnO ₂ with dendritic hierarchical structure was synthesized by a simple hydrothermal method, tin tetrachloride pentahydrate was used as tin source, urea was used as precipitant, polyethylene glycol 6000 was used as surfactant, and a certain The process parameters such as reactant concentration, reaction time and reaction temperature can control the morphology and size of the synthesized hierarchical structure tin oxide within a certain range. The advantage of this method is that the cost is low, the synthesis process is simple, no organic solvent or strong acid is used in the process, the process is environmentally friendly and safe, and the dendritic tin dioxide prepared by this method has a special structure, good dispersion, uniform size, and excellent sensitivity. performance.

Contents of the invention

The purpose of the present invention is to overcome the existing shortcoming of the prior art, propose a kind of synthesis process simple, cheap, environmental protection safety, size controllable, the preparation method of dendritic structure _SnO of wide range of application, eliminate traditional preparation method Disadvantages such as high energy consumption, low yield, and single morphology. The synthesis method has the advantages of low production cost, no pollution to the environment, high yield, and can be industrialized. The prepared dendritic SnO ₂ has a special shape, uniform size, and good sensitivity. It can be used to make moisture-sensitive The sensing element can effectively improve the response to humidity. The humidity sensitive performance of the dendritic structure _SnO2 prepared by the present invention is obtained through an AC impedance test.

The technical scheme that realizes the object of the present invention: a kind of dendritic structure _SnO that is used for moisture-sensitive device material Preparation method, it is characterized in that, with tin tetrachloride (pentahydrate) as reaction raw material, urea is as alkali source, with Polyethylene glycol 6000 is used as a surfactant, deionized water is used as a dispersant, and tin oxide nanomaterials with a dendritic structure are obtained through hydrothermal reaction. However, in the prior art, most of them use stannous chloride (SnCl ₂ 2H ₂ O) and sodium hydroxide as raw materials, the disadvantages are as follows: first, because the solubility of tin protochloride in water is small, and the conversion into Sn(OH) requires a sufficiently large pH value; _second , in order to make Sn(OH) ) ₂ into Sn(OH) ₄ , so NaOH is usually used as the alkali source to control the pH value of the solution; thirdly, to fully decompose Sn(OH) ₄ into SnO ₂ , it needs a long enough time and a high enough temperature to carry out hydrothermal reaction. The reaction raw material selected in the present invention is SnCl ₄ ·5H ₂ O, which has high solubility in water, does not need to add strong alkali to increase the pH value, and directly generates Sn(OH) ₄ . In the present invention, the formation mechanism of SnO ₂ dendritic structure is as follows, and SnCl ₄ ·5H ₂ O, PEG6000 and urea play key roles. First, in the solution, SnCl ₄ ·5H ₂ O releases Sn ⁴⁺ through hydrolysis, and urea, as a weak base, can be dissolved in deionized water to provide OH ^- , which reacts with Sn ⁴⁺ ions to produce Sn(OH) ₄ , hydrothermal Under the conditions, Sn(OH) ₄ decomposes into SnO ₂ . Under the assisted conditions of PEG6000, the assembly of micro-nano particles and the formation of dendritic SnO ₂ structures are promoted. After testing, the dendritic tin oxide sensing element based on the interdigitated electrodes has an excellent humidity-sensing response to humidity.

The method adopted in the present invention involves many factors, such as reaction temperature, reaction time and so on. Concrete synthetic steps are as follows:

1. Preparation of Dendritic _SnO2 Hierarchical Structured Materials

(1) Weigh urea and polyethylene glycol 6000, dissolve in deionized water, and stir in a water bath to form a uniform solution.

(2) Weigh tin tetrachloride pentahydrate (SnCl ₄ ·5H ₂ O), and dissolve it into a uniform solution to obtain a mixed solution.

(3) Transfer the mixed solution to a polytetrafluoroethylene-lined stainless steel hydrothermal kettle and seal it.

(4) Put the hydrothermal kettle into an oven for hydrothermal reaction. After the reaction is over, cool it down to room temperature naturally, and obtain the dendritic _SnO2 hierarchical structure material after separation, washing and drying of the white product.

The concentration of urea in the mixed solution is 0.1-0.4 mol/L; the concentration of SnCl ₄ ·5H ₂ O is 0.02-0.06 mol/L.

The addition amount of described polyethylene glycol 6000 is 1g.

The temperature of the water bath is 40°C.

The hydrothermal reaction temperature is 140°C-200°C, and the reaction time is 6-12 hours.

The separation refers to separation with a centrifuge, the washing refers to washing with ethanol and deionized water, and the drying temperature is 80°C.

2. Manufacture of humidity sensor and test of humidity sensor performance

(1) Weigh dendritic SnO ₂ hierarchical structure material powder and mix it with deionized water, the mass ratio of SnO ₂ powder and deionized water is 3:1, fully wet grind in a mortar until a viscous slurry is formed material.

(2) Apply the prepared paste evenly on the interdigitated electrodes by screen printing, the thickness should be just covered with the gold electrodes, and then place the electrode sheets at 60°C to dry to constant weight.

(3) Sinter at 400°C-500°C to make it stable, and the tin oxide humidity sensor can be produced.

(4) Using the two-electrode method, an electrochemical potentiostat is used to perform impedance tests under different humidity, and the frequency range is 0.01-100 kHz.

Use a saturated solution of salt to control the humidity (25°C). The humidity corresponding to the saturated solution of MgCl ₂ , K ₂ CO ₃ , NaBr, NaCl, KCl and H ₂ O is 33%, 43%, 59%, 75%, 85% respectively , 98%.

Description of drawings

Fig. 1 is dendritic structure _SnO that the present invention makes XRD collection of illustrative plates, among the figure 1 characteristic peaks and _SnO The characteristic peaks of powder diffractogram match, illustrate that this preparation method can obtain stable _SnO Structure;

Fig. 2 is the dendritic structure SnO that the present invention makes ₂ low-magnification SEM figure, can find out from the figure that the _SnO that this method prepares presents dendritic structure, and appearance is special;

Fig. 3 is the dendritic structure _SnO that the present invention makes High magnification SEM figure, can find out from the figure that the size of the end of branch is 3 microns;

Fig. 4 is the dendritic structure SnO that the present invention makes ₂ AC impedance diagrams under different relative humidity conditions, as can be seen from the figure, the dendritic structure _SnO that this method prepares has higher sensitivity to humidity response.

FIG. 5 is an enlarged schematic view of the panel in FIG. 4 .

specific implementation

Below in conjunction with accompanying drawing and embodiment, the present invention is described in further detail, and present embodiment is carried out under the premise of technical solution of the present invention, provides multiple specific implementation modes and detailed operation steps, but is not limited in any way scope of the invention.

Example 1

1. Preparation of Dendritic _SnO2 Hierarchical Structured Materials

(1) Weigh a certain amount of urea and 1.0 g of polyethylene glycol 6000 (PEG6000), dissolve them in deionized water, and stir in a water bath at 40°C to form a uniform solution, wherein the concentration of urea is 0.2 mol/L;

(2) Weigh a certain amount of tin tetrachloride pentahydrate (SnCl ₄ 5H ₂ O), dissolve it in the above solution, and control its concentration at 0.035mol/L;

(3) above-mentioned solution is transferred in polytetrafluoroethylene-lined stainless steel hydrothermal kettle, seals;

(4) Put the hydrothermal kettle into the oven, carry out the hydrothermal reaction at a temperature of 160°C, and the reaction time is 6 hours. After the reaction, naturally cool to room temperature, and the white product obtained is separated by a centrifuge and washed with ethanol and deionized water Several times, dry at 80°C.

Example 2

1. Preparation of Dendritic _SnO2 Hierarchical Structured Materials

(1) Weigh a certain amount of urea and 1.0 g of polyethylene glycol 6000 (PEG6000), dissolve them in deionized water, and stir in a water bath at 40°C to form a uniform solution, wherein the concentration of urea is 0.2 mol/L;

(2) Weigh a certain amount of tin tetrachloride pentahydrate (SnCl ₄ 5H ₂ O), dissolve it in the above solution, and control its concentration at 0.04mol/L;

(3) above-mentioned solution is transferred in polytetrafluoroethylene-lined stainless steel hydrothermal kettle, seals;

(4) Put the hydrothermal kettle into the oven, carry out the hydrothermal reaction at 180°C, and the reaction time is 8 hours. After the reaction, cool down to room temperature naturally, and the white product obtained is separated by a centrifuge and washed with ethanol and deionized water. Several times, dry at 80°C.

Example 3

1. Preparation of Dendritic _SnO2 Hierarchical Structured Materials

(1) Weigh a certain amount of urea and 1.0 g of polyethylene glycol 6000 (PEG6000), dissolve in deionized water, and stir in a water bath at 40°C to form a uniform solution, wherein the concentration of urea is 0.25mol/L;

(2) Weigh a certain amount of tin tetrachloride pentahydrate (SnCl ₄ 5H ₂ O), dissolve it in the above solution, and control its concentration at 0.045mol/L;

(3) Transfer the above solution to a 100ml polytetrafluoroethylene-lined stainless steel hydrothermal kettle, and seal it;

(4) Put the hydrothermal kettle into the oven, carry out the hydrothermal reaction at a temperature of 160°C, and the reaction time is 12 hours. After the reaction is completed, it is naturally cooled to room temperature, and the white product obtained is separated by a centrifuge and washed with ethanol and deionized water. Several times, dry at 80°C.

Example 4

1. Preparation of Dendritic _SnO2 Hierarchical Structured Materials

(1) Weigh a certain amount of urea and 1.0 g of polyethylene glycol 6000 (PEG6000), dissolve in deionized water, and stir in a water bath at 40°C to form a uniform solution, wherein the concentration of urea is 0.35mol/L;

(2) Weigh a certain amount of tin tetrachloride pentahydrate (SnCl ₄ 5H ₂ O), dissolve it in the above solution, and control its concentration at 0.05mol/L;

(3) Transfer the above solution to a 100ml polytetrafluoroethylene-lined stainless steel hydrothermal kettle, and seal it;

(4) Put the hydrothermal kettle into the oven, carry out the hydrothermal reaction at 180°C, and the reaction time is 10 hours. After the reaction, naturally cool to room temperature, and the white product obtained is separated by a centrifuge and washed with ethanol and deionized water. Several times, dry at 80°C.

Example 5

1. Preparation of Dendritic _SnO2 Hierarchical Structured Materials

(1) Weigh a certain amount of urea and 1.0 g of polyethylene glycol 6000 (PEG6000), dissolve in deionized water, and stir in a water bath at 40°C to form a uniform solution, wherein the concentration of urea is 0.4 mol/L;

(2) Weigh a certain amount of tin tetrachloride pentahydrate (SnCl ₄ 5H ₂ O), dissolve it in the above solution, and control its concentration at 0.06mol/L;

(3) Transfer the above solution to a 100ml polytetrafluoroethylene-lined stainless steel hydrothermal kettle, and seal it;

(4) Put the hydrothermal kettle into the oven, carry out the hydrothermal reaction at 200°C, and the reaction time is 10 hours. After the reaction, cool down to room temperature naturally, and the white product obtained is separated by a centrifuge and washed with ethanol and deionized water. Several times, dry at 80°C.

Experimental results

Dendritic _SnO prepared in Example 1 The XRD spectrum of the X-ray powder diffraction test obtained through the hierarchical structure, as shown in Figure 1; the low-power and high-power SEM figures taken by a scanning electron microscope, as shown in Figure 2 and Figure 3 Figure 4 shows the AC impedance diagrams of dendritic tin oxide sensitive elements based on interdigitated electrodes measured under different relative humidity conditions.

It can be seen from Fig. 1 that the positions of all diffraction peaks of the XRD spectrum of the sample prepared by the present invention are consistent with the international diffraction data standard card JCPDS Card No.41-1445, the crystallinity is good, and no other impurity peaks appear.

From the low-magnification SEM image in Figure 2, it can be seen that the morphology of the obtained sample is a dendritic structure. The dendritic structure is assembled from a large number of particles, and the shape is regular. The length of the overall _SnO2 skeleton can reach tens of microns. The particle size of the branch end particles is 3 μm; from the high-magnification SEM image of Figure ₃ , it can be seen that the particles at the end of the dendritic structure are obviously larger than those in other regions. growth movement.

Fig. 4 is the AC impedance figure that the dendritic structure _SnO sensitive element based on interdigitated electrode in embodiment 1 records under different relative humidity conditions, as can be seen, along with the increase of humidity, the measured impedance value decreased sharply, exhibiting good humidity sensitivity properties.

Claims (8)

1. a kind of preparation method of dendritic hierarchy tin ash, it is characterised in that comprise the following steps that：

(1) urea and Macrogol 6000 are weighed, is dissolved in deionized water, stirred in water bath forms homogeneous solution；

(2) Tin tetrachloride pentahydrate (SnCl is weighed₄·5H₂O), it is dissolved into homogeneous solution and obtains mixed solution；

(3) mixed solution is transferred in polytetrafluoroethyllining lining stainless steel water heating kettle, is sealed；

(4) water heating kettle is put into baking oven, carries out hydro-thermal reaction, after reaction terminates, naturally cool to room temperature, gained white product warp Dendritic hierarchy SnO is obtained after separation, washing, drying₂。

2. a kind of preparation method of dendritic hierarchy tin ash as claimed in claim 1, it is characterised in that the mixing The concentration of urea is 0.1-0.4mol/L in solution；SnCl₄·5H₂The concentration of O is 0.02-0.06mol/L.

3. a kind of preparation method of dendritic hierarchy tin ash as claimed in claim 1, it is characterised in that the poly- second The addition of glycol 6000 is 1g.

4. a kind of preparation method of dendritic hierarchy tin ash as claimed in claim 1, it is characterised in that the water-bath Temperature is 40 DEG C.

5. a kind of preparation method of dendritic hierarchy tin ash as claimed in claim 1, it is characterised in that the hydro-thermal Reaction temperature is 140 DEG C~200 DEG C, and the reaction time is 6-12 hours.

6. a kind of preparation method of dendritic hierarchy tin ash as claimed in claim 1, it is characterised in that the separation Finger is separated with centrifuge, and washing refers to is washed with ethanol and deionized water, and drying temperature is 80 DEG C.

7. the dendritic hierarchy tin ash that prepared by method as claimed in claim 1 is used to prepare the use of wet sensitive device material On the way.

8. purposes as claimed in claim 7, it is characterised in that preparation method is as follows：

(1) weigh dendritic hierarchy tin dioxide powder to mix with deionized water, the mass ratio of powder and deionized water is 3: 1, the abundant wet-milling in mortar, until forming sticky slurry；

(2) slurry that will have been configured with silk-screen printing is coated uniformly in interdigital electrode, and then electrode slice is placed at 60 DEG C Dry to constant weight；

Sintering consolidates it at (3) 400 DEG C -500 DEG C, you can tin oxide wet sensitive device is obtained.