阅读说明：本技术 一种多孔黑硅材料的制备方法、荧光传感器制备方法及其用于检测爆炸物的方法 (Preparation method of porous black silicon material, preparation method of fluorescent sensor and method for detecting explosive by using fluorescent sensor ) 是由 王涛平 傅得锋 孙景志 于 2021-08-09 设计创作，主要内容包括：本发明公开了一种多孔黑硅材料的制备方法、荧光传感器制备方法及其用于检测爆炸物的方法；将异丙醇和去离子水共混,并向混合后的异丙醇溶液中加入可溶性无机碱；取无机硝酸铁溶于去离子水中配置得硝酸铁溶液,再加入氢氟酸,混合均匀后得到酸刻蚀液；将清洁的硅片浸没到碱刻蚀液中,浸没并清洗后得到碱刻蚀硅片；将碱刻蚀硅片浸没到酸刻蚀液中,浸没、洗净后即得到多孔黑硅材料；通过碱性蚀刻液将其刻蚀成尖锥形状,然后经酸液水热蚀刻进行表面改性得到多孔结构的黑硅材料。本发明还制备了以此为基底的多孔黑硅气体荧光传感器!该气体荧光传感器在爆炸物探测器中作为敏感材料检测硝基芳烃爆炸物TNT,TNT的最低检测限量可达到0.1ng水平。(The invention discloses a preparation method of a porous black silicon material, a preparation method of a fluorescent sensor and a method for detecting explosives by using the fluorescent sensor; blending isopropanol and deionized water, and adding soluble inorganic base into the mixed isopropanol solution; dissolving inorganic ferric nitrate in deionized water to prepare ferric nitrate solution, adding hydrofluoric acid, and uniformly mixing to obtain acid etching solution; immersing the cleaned silicon wafer into an alkali etching solution, and immersing and cleaning to obtain an alkali etching silicon wafer; immersing the alkali etching silicon wafer into the acid etching solution, and immersing and cleaning to obtain a porous black silicon material; etching the black silicon material into a pointed cone shape by using alkaline etching solution, and then carrying out surface modification by acid solution hydrothermal etching to obtain the black silicon material with a porous structure. The invention also prepares a porous black silicon gas fluorescence sensor using the material as a substrate! The gas fluorescence sensor is used as a sensitive material in an explosive detector to detect the TNT (nitroaromatic hydrocarbon) explosive, and the minimum detection limit of the TNT can reach a level of 0.1 ng.)

1. A preparation method of a porous black silicon material is characterized by comprising the following steps:

s1, blending isopropanol and deionized water in a volume ratio of 6:1-3:1, adding soluble inorganic alkali into the mixed isopropanol solution, and dissolving to obtain alkali etching solution with the mass concentration of 1-3 wt%;

s2, dissolving inorganic nitrate in deionized water to prepare a ferric nitrate solution with the concentration of 0.1-0.3mol/L, adding hydrofluoric acid with the volume 2-4 times of that of the deionized water, and uniformly mixing to obtain an acid etching solution;

s3, immersing the cleaned silicon wafer into the alkali etching solution obtained in the step 1, wherein the temperature of the solution is maintained at 70-100 ℃, immersing for 20-40min, and cleaning to obtain an alkali etching silicon wafer;

s4, immersing the alkali-etched silicon wafer obtained in the step 3 into the acid etching solution obtained in the step 2, immersing for 20-60min at 80-120 ℃, and cleaning to obtain the porous black silicon material.

2. The method for preparing a porous black silicon material according to claim 1, wherein the soluble inorganic base in step 1 is potassium hydroxide powder.

3. The method for preparing the porous black silicon material according to claim 1, wherein the hydrofluoric acid concentration in the step 2 is 40 wt%.

4. The method for preparing the porous black silicon material according to claim 1, wherein the alkali-etched silicon wafer and the porous black silicon material in the steps 3 and 4 are taken out from the etching solution, and then are sequentially subjected to ultrasonic treatment for 5-10min in beakers of acetone, ethanol and deionized water, wherein the ultrasonic treatment is repeated for about 3 times, and N is used₂And drying to obtain the porous black silicon material.

5. A preparation method of a porous black silicon material gas fluorescence sensor is characterized by comprising the following steps:

s1, dissolving a fluorescent high polymer material in an organic solvent, and uniformly mixing to obtain a high polymer solution with the concentration of 2-4 mg/mL;

s2, coating the polymer solution obtained in the step 1 on a porous black silicon material, drying the porous black silicon material at 80-100 ℃ for 1-5 hours in vacuum, and drying to obtain the porous black silicon material gas fluorescence sensor.

6. The method of claim 5, wherein the solvent is one of toluene, dimethylsulfoxide, or chloroform.

7. The method according to claim 5, wherein the polymer material is poly [ 2-methoxy-5- (2-ethylhexyloxy) -1, 4-phenylacetylene ].

8. A method for detecting aromatic nitro explosive trinitrotoluene by using a porous black silicon material gas sensor is characterized by comprising the following steps:

s1, dissolving TNT in an organic solvent to prepare a TNT solution with the concentration of 1-10 ng/mL;

s2, taking the porous black silicon material coated with the fluorescent polymer solution as a fluorescent substance, preparing a carrier, and putting the carrier into an explosive detector to serve as a sensing material;

s3, adsorbing the TNT solution with different material quantities prepared in the step 1 onto the sensing material prepared in the step 2, detecting the change of the fluorescence intensity of the system along with the TNT content, calculating the detection sensitivity and determining the detection limit, wherein the detection sensitivity and the detection limit are determined by a relation curve of the fluorescence intensity of the system along with the change of the TNT concentration.

9. The method according to claim 8, wherein the organic solvent is one of acetonitrile, methanol, and acetone.

Technical Field

The invention relates to the technical field of preparation of gas fluorescent sensors, in particular to a preparation method of a porous black silicon material, a preparation method of a fluorescent sensor and a method for detecting explosives by using the fluorescent sensor.

Background

The micro trace explosive detection technology mainly comprises various spectrum technologies, chemical sensor technologies, biosensor technologies and the like, the chemical sensor technology based on fluorescence quenching effect is an effective sensing method in the explosive detection field due to the advantages of high sensitivity, good selectivity, high response speed, simplicity in operation, strong portability, low cost and the like, and has wide application prospects in the fields of gas sensing, environmental monitoring and the like, and attracts more and more researchers.

Chemical sensors mainly include three types: at present, in terms of development prospects, electrochemical sensors, optical sensors and mass sensors are classified into homogeneous (solution) fluorescence sensors, thin-film fluorescence sensors, optical fiber fluorescence sensors and the like according to the relationship between the sensors and a sample to be measured, with the fluorescence chemical sensors possibly closer to practical applications. The thin film fluorescent sensor has the advantages of long service life, convenient use, easy device formation and the like, so that the thin film fluorescent sensor is gradually developed into a new explosive detection method with great development prospect, and is highly concerned by researchers. For the constituent materials of the thin film fluorescent sensor, conjugated fluorescent polymer thin films, dye-doped or modified polymer thin films and dye-doped oxide thin films are available.

The thin film fluorescence sensor is based on a fluorescence sensor which is attached to a substrate to form a film, the surface of the substrate does not have a porous structure (a glass sheet, a simple silicon sheet and the like), the smooth surface is simply utilized, and compared with the porous structure of the self material, the specific surface area is small, and the adsorbability is poor. The black silicon material is a novel porous structure, is extremely sensitive to light, has a near-zero reflection rate in a near ultraviolet-infrared band, and has a dramatic improvement compared with common crystalline silicon. Black silicon has a very low reflectance mainly due to light trapping phenomenon caused by its rough surface: when light is incident to the inclined plane with a certain angle, the light can be reflected to the inclined plane with another angle to form secondary or multiple absorption, so that the absorption rate is increased. Therefore, the fluorescent sensor prepared from the porous black silicon material has the advantages of convenience in preparation, simplicity in operation, high detection sensitivity, low preparation cost and the like.

In 1998, black silicon, a new material, was unexpectedly obtained after the surface of a silicon wafer was irradiated with high-energy femtosecond laser pulses in the process of studying the interaction between femtosecond laser and a substance by a professor of Mazur, Harvard university. The surface of the black silicon material is found to have a quasi-regular array of tiny pointed cones similar to a forest pattern through research. In addition, the black silicon material has very high absorptivity (near ultraviolet-infrared light absorptivity is up to more than 90%), and has good luminescence property and field emission property. However, the femtosecond laser has complicated device operation steps, high instrument cost, and ultrahigh pulse power, and the inside of a material substrate is easily damaged during the preparation of a black silicon material.

Disclosure of Invention

The invention provides a preparation method of a porous black silicon material, a preparation method of a fluorescence sensor and a method for detecting explosives by using the fluorescence sensor. The preparation method of the porous black silicon material has the advantages of simple and easy operation, mild reaction conditions, easily obtained raw materials and low cost, and comprises the following specific steps:

a preparation method of a porous black silicon material comprises the following steps:

s1, blending isopropanol and deionized water in a volume ratio of 6:1-3:1, adding soluble inorganic alkali into the mixed isopropanol solution, and dissolving to obtain alkali etching solution with a mass concentration of 1-3 wt%;

s2, dissolving inorganic nitrate in deionized water to prepare an iron nitrate solution with the concentration of 0.1-0.3mol/L, adding hydrofluoric acid with the volume 2-4 times of that of the deionized water, and uniformly mixing to obtain an acid etching solution;

s3, immersing the cleaned silicon wafer into the alkali etching solution obtained in the step 1, wherein the temperature of the solution is maintained at 70-100 ℃, immersing for 20-40min, and cleaning to obtain an alkali etching silicon wafer;

s4, immersing the alkali-etched silicon wafer obtained in the step 3 into the acid etching solution obtained in the step 2, immersing for 20-60min at 80-120 ℃, and cleaning to obtain the porous black silicon material.

Further, the soluble inorganic base in step 1 is potassium hydroxide powder.

Further, the hydrofluoric acid concentration in the step 2 is 40 wt%.

Further, after the alkali etching silicon wafer and the porous black silicon material in the steps 3 and 4 are taken out from the etching solution, ultrasonic treatment is sequentially carried out for 5-10min in a beaker of acetone, ethanol and deionized water, the ultrasonic treatment is repeated for about 3 times, and N is used₂And drying to obtain the porous black silicon material.

The invention also discloses a preparation method of the porous black silicon material gas fluorescence sensor, which comprises the following steps:

s1, dissolving a fluorescent high polymer material in an organic solvent, and uniformly mixing to obtain a high polymer solution with the concentration of 2-4 mg/mL;

s2, coating the polymer solution obtained in the step 1 on a porous black silicon material, drying the porous black silicon material at 80-100 ℃ for 1-5 hours in vacuum, and drying to obtain the porous black silicon material gas fluorescence sensor.

Further, the solvent is one of toluene, dimethyl sulfoxide or chloroform.

Further, the high polymer material is poly [ 2-methoxy-5- (2-ethylhexyloxy) -1, 4-phenylethynyl ].

The invention also discloses a method for detecting aromatic nitro explosive trinitrotoluene (TNT) by using the porous black silicon material gas sensor, which comprises the following steps

S1, dissolving TNT in an organic solvent to prepare a TNT solution with the concentration of 1-10 ng/mL;

s2, taking the porous black silicon material coated with the fluorescent polymer solution as a fluorescent substance, preparing a carrier, and putting the carrier into an explosive detector to serve as a sensing material;

s3, adsorbing the TNT solution with different material quantities prepared in the step 1 onto the sensing material prepared in the step 2, detecting the change of the fluorescence intensity of the system along with the TNT content, calculating the detection sensitivity and determining the detection limit, wherein the detection sensitivity and the detection limit are determined by a relation curve of the change of the fluorescence intensity of the system along with the TNT concentration.

Further, the organic solvent is one of acetonitrile, methanol and acetone.

Compared with the prior art, the fluorescence sensor prepared by the invention has the following advantages:

1. the porous black silicon material prepared by metal-assisted hydrothermal method has excellent photoluminescence effect, very high light absorption rate (about 95% as high as possible); 2. the nano-aperture on the surface of the porous black silicon is controllable and uniform, so that the uniformity of the fluorescent sensor taking the porous black silicon as the substrate is greatly enhanced; 3. the specific surface area of the porous black silicon is large, the performance of high adsorption rate also increases the contact area of the gas fluorescence sensor and the gas to be detected, so that the gas adsorption rate is greatly increased; 4. the process has simple operation, mild reaction conditions and high yield, and is suitable for large-scale production; 5. the material has good stability, long service life and high sensitivity for detecting explosives (such as TNT).

Drawings

FIG. 1 is a scanning electron microscope image of the porous black silicon material prepared in example 1 of the present invention.

FIG. 2 is a scanning electron microscope image of the porous black silicon material prepared in example 2 of the present invention.

FIG. 3 is a scanning electron microscope image of a silicon wafer etched by an alkaline solution in example 3 of the present invention.

FIG. 4 is a scanning electron microscope image of the porous black silicon material prepared in example 3 of the present invention.

FIG. 5 is a scanning electron microscope image of a silicon wafer etched by an alkaline solution in example 5 of the present invention.

FIG. 6 is a comparison of the porous black silicon material obtained in example 3 of the present invention and a silicon wafer without etching.

FIG. 7 is a scanning electron microscope image of the porous black silicon material prepared in example 4 of the present invention.

Fig. 8 is a graph of fluorescence spectra (PL) of the porous black silicon material and the fluorescent gas sensor in application example 1 of the present invention.

FIG. 9 is a graph showing the relationship between the fluorescence intensity of the system and the fluorescence intensity before and after the addition of TNT when the fluorescent gas sensor made of the porous black silicon material in application example 3 of the present invention performs fluorescence detection on TNT.

Detailed Description

In order to further understand the present invention, the following specifically describes the preparation method of a porous black silicon material, the preparation method of a fluorescence sensor and the method for detecting explosives, which are provided by the present invention, with reference to the following examples, but the present invention is not limited to these examples. The non-essential modification and adjustment made by the person skilled in the art guided by the above disclosure of the invention still belong to the protection scope of the invention.

Example 1

At room temperature, 2.4g of potassium hydroxide powder is weighed by an electronic scale and put into a beaker, then 60ml of isopropanol and 180ml of deionized water solution are weighed by a dosing cylinder, wherein the volume ratio of the deionized water to the isopropanol solution is 3:1, and the mixed solution is prepared into KOH solution with the concentration of 1%; then transferring the obtained solution beaker into a constant-temperature water bath kettle, setting the temperature at 80 ℃ and the time at 30 min; completely immersing the cleaned silicon wafer into a beaker for alkali etching when the temperature of the constant-temperature water bath is stable; after the reaction is finished, taking out the silicon chip etched by the alkali, sequentially putting the silicon chip into a beaker filled with acetone, ethanol and deionized water for ultrasonic treatment for 5-10min, repeating the process for about 3 times, and then using N₂Drying for later use; weighing ferric nitrate powder by using an electronic scale, putting the ferric nitrate powder into a beaker, preparing 80ml of ferric nitrate aqueous solution with the concentration of 0.1mol/l, uniformly stirring the ferric nitrate aqueous solution until the ferric nitrate aqueous solution is completely dissolved, transferring the solution into a lining of a 100ml polytetrafluoroethylene reaction kettle, and then measuring hydrofluoric acid with the volume ratio by using a plastic measuring cylinder: pouring deionized water at a ratio of 2.5:1 into the inner liner of the reaction kettle, and shaking up the mixed solution; immersing the silicon wafer subjected to alkali etching in the mixed solution of the inner liner of the reaction kettle, screwing a cover, and transferring to a baking oven for acid etching at the set temperature of 100 ℃ for 20 min; after the reaction is finished, taking out the silicon chip and putting the silicon chip into a reactor filled with acetone, ethanol and deionized water in sequencePerforming ultrasonic treatment in water beaker for 5-10min, repeating the above steps for about 3 times, and adding N₂Drying by blowing to obtain the required porous black silicon material, wherein the porous black silicon structure under a scanning electron microscope is in a sponge porous structure as shown in figure 1; a fluorescence spectrum (PL) diagram of a fluorescence sensor prepared on the basis of the porous black silicon is shown in FIG. 8, wherein a y1 curve is a fluorescence spectrum of the porous black silicon material, and y2 is a fluorescence spectrum of the fluorescence sensor based on the porous black silicon material.

Example 2

At room temperature, 2.4g of potassium hydroxide powder is weighed by an electronic scale and put into a beaker, then 60ml of isopropanol and 180ml of deionized water solution are weighed by a dosing cylinder, wherein the volume ratio of the deionized water to the isopropanol solution is 3:1, and the mixed solution is prepared into KOH solution with the concentration of 1%; then transferring the obtained solution beaker into a constant-temperature water bath kettle, setting the temperature at 80 ℃ and the time at 30 min; completely immersing the cleaned silicon wafer into a beaker for alkali etching when the temperature of the constant-temperature water bath is stable; after the reaction is finished, taking out the silicon chip etched by the alkali, sequentially putting the silicon chip into a beaker filled with acetone, ethanol and deionized water for ultrasonic treatment for 5-10min, repeating the process for about 3 times, and then using N₂Drying for later use; weighing ferric nitrate powder by using an electronic scale, putting the ferric nitrate powder into a beaker, preparing 80ml of ferric nitrate aqueous solution with the concentration of 0.1mol/l, uniformly stirring the ferric nitrate aqueous solution until the ferric nitrate aqueous solution is completely dissolved, transferring the solution into a lining of a 100ml polytetrafluoroethylene reaction kettle, and then measuring hydrofluoric acid with the volume ratio by using a plastic measuring cylinder: pouring deionized water at a ratio of 2.5:1 into the inner liner of the reaction kettle, and shaking up the mixed solution; immersing the silicon wafer subjected to alkali etching in the mixed solution of the inner liner of the reaction kettle, screwing a cover, and transferring to a baking oven for acid etching at the set temperature of 100 ℃ for 30 min; after the reaction is finished, taking out the silicon chip, sequentially putting the silicon chip into a beaker filled with acetone, ethanol and deionized water for ultrasonic treatment for 5-10min, repeating the process for about 3 times, and then using N to treat the silicon chip₂Blow-drying to obtain the required porous black silicon material, and the scanning electron micrograph thereof is shown in figure 2.

Example 3

At room temperature, 2.4g of potassium hydroxide powder was weighed into a beaker using an electronic scale, and thenWeighing 60ml of isopropanol and 180ml of deionized water solution by using a measuring cylinder, wherein the volume ratio of the deionized water to the isopropanol solution is 3:1, and preparing the mixed solution into a KOH solution with the concentration of 1%; then transferring the obtained solution beaker into a constant-temperature water bath kettle, setting the temperature at 80 ℃ and the time at 30 min; completely immersing the cleaned silicon wafer into a beaker for alkali etching when the temperature of the constant-temperature water bath is stable; after the reaction is finished, taking out the silicon chip etched by the alkali, sequentially putting the silicon chip into a beaker filled with acetone, ethanol and deionized water for ultrasonic treatment for 5-10min, repeating the process for about 3 times, and then using N₂Blow-drying for standby (see fig. 3 for an electron microscope image thereof); weighing ferric nitrate powder by an electronic scale, putting the ferric nitrate powder into a beaker, preparing 80ml of ferric nitrate aqueous solution with the concentration of 0.1mol/l, uniformly stirring the ferric nitrate aqueous solution until the ferric nitrate aqueous solution is completely dissolved, transferring the solution into a 100ml inner liner of a polytetrafluoroethylene reaction kettle, and then measuring hydrofluoric acid with the volume ratio by a plastic measuring cylinder: pouring deionized water at a ratio of 2.5:1 into the inner liner of the reaction kettle, and shaking up the mixed solution; immersing the silicon wafer subjected to alkali etching in the mixed solution of the inner liner of the reaction kettle, screwing a cover, and transferring to a baking oven for acid etching at the temperature of 100 ℃ for 40 min; after the reaction is finished, taking out the silicon chip, sequentially putting the silicon chip into a beaker filled with acetone, ethanol and deionized water for ultrasonic treatment for 5-10min, repeating the process for about 3 times, and then using N to treat the silicon chip₂Blow-drying to obtain the required porous black silicon material, and the scanning electron micrograph thereof is shown in figure 4.

The porous black silicon material obtained in example 3 was compared with a pure silicon wafer, and a comparison graph is shown in fig. 6.

Example 4

At room temperature, 7.2g of potassium hydroxide powder is weighed by an electronic scale and put into a beaker, then 60ml of isopropanol and 180ml of deionized water solution are weighed by a dosing cylinder, wherein the volume ratio of the deionized water to the isopropanol solution is 3:1, and the mixed solution is prepared into 3% KOH solution; then transferring the obtained solution beaker into a constant-temperature water bath kettle, setting the temperature at 80 ℃ and the time at 30 min; completely immersing the cleaned silicon wafer into a beaker for alkali etching when the temperature of the constant-temperature water bath is stable; after the reaction is finished, taking out the silicon wafers etched by the alkali and sequentially putting the silicon wafers into the container filled with the silicon waferUltrasonic treating in beaker containing ketone, ethanol and deionized water for 5-10min, repeating for about 3 times, and adding N₂Drying for later use; weighing ferric nitrate powder by using an electronic scale, putting the ferric nitrate powder into a beaker, preparing 80ml of ferric nitrate aqueous solution with the concentration of 0.1mol/l, uniformly stirring the ferric nitrate aqueous solution until the ferric nitrate aqueous solution is completely dissolved, transferring the solution into a lining of a 100ml polytetrafluoroethylene reaction kettle, and then measuring hydrofluoric acid with the volume ratio by using a plastic measuring cylinder: pouring deionized water at a ratio of 2.5:1 into the inner liner of the reaction kettle, and shaking up the mixed solution; immersing the silicon wafer subjected to alkali etching in the mixed solution of the inner liner of the reaction kettle, screwing a cover, and transferring to a baking oven for acid etching at the set temperature of 100 ℃ for 30 min; after the reaction is finished, taking out the silicon chip, sequentially putting the silicon chip into a beaker filled with acetone, ethanol and deionized water for ultrasonic treatment for 5-10min, repeating the process for about 3 times, and then using N to treat the silicon chip₂Blow-drying to obtain the required porous black silicon material, and the scanning electron microscope picture of the porous black silicon material is shown in figure 8.

Example 5

The difference between the embodiment 5 and the embodiment 3 is that after the isopropanol solution is prepared, the soluble inorganic base added is sodium hydroxide, and the scanning electron microscope image of the finally prepared porous black silicon material is shown in fig. 5, and the scanning electron microscope image shows that the silicon wafer etched by the sodium hydroxide and the silicon wafer etched by the potassium hydroxide can achieve the silicon wafer surface appearance which is basically the same.

Example 6

The fluorescence sensor for preparing the porous black silicon material by metal-assisted hydrothermal method can be used for detecting TNT, and the detection steps are as follows:

the sample concentration of the standard substance is diluted to 10 ng/. mu.L by taking acetone as a solvent, and then the sample concentration is respectively diluted to TNT solutions of 1 ng/. mu.L, 2 ng/. mu.L and 5 ng/. mu.L. Taking the porous black silicon material obtained in example 3 as a substrate, cutting a black silicon wafer coated with a fluorescent polymer into small pieces of 4cm × 4cm, placing the pieces of black silicon wafer into an explosive detector as a sensing material, and referring to fig. 9, detecting the relationship between the fluorescence intensity of an explosive and a time curve for the sensor, wherein a region a represents a self-decay curve of the fluorescence intensity of the material with time; region b represents the time-dependent fluorescence intensity profile of the sensor during operation; the point c is the moment when the sensor detects the explosive, the fluorescence intensity is rapidly reduced due to the fluorescence quenching effect, and then the fluorescence intensity enters the section d and is increased; region d represents the time-dependent fluorescence intensity after detection of the explosives by the sensor.

The preparation method of the black silicon material is more and more diversified after more than twenty years of research. Here we have developed a new process of metal assisted acid-base hydrothermal etching, which effectively solves these problems. Firstly, alkali etching is carried out on a silicon wafer, a pyramid-shaped pointed cone structure is formed on the surface of the silicon wafer, the surface of the obtained structure is rough, and metal-assisted acid etching is carried out on the rough surface to modify the rough surface to obtain a porous pointed cone array-shaped structure. The porous black silicon material has the advantages of stable structure, high photoluminescence efficiency, uniform surface pore diameter and the like. The material is coated with fluorescent polymer solution in a spinning way, and the porous black silicon gas fluorescent sensor which can be used for detecting explosives is obtained after vacuum drying.