阅读说明：本技术 一种纳米氧化铬的生物模板制备方法及其在气敏传感中的应用 (Preparation method of biological template of nano chromium oxide and application of biological template in gas-sensitive sensing ) 是由 奚亚男 胡淑锦 于 2020-09-29 设计创作，主要内容包括：本发明提供了一种纳米氧化铬的生物模板制备方法及其在气敏传感中的应用。本发明以蛋膜为模板,Cr(NO_3)_3·9H_2O为原料,采用溶剂热法与模板法结合的方法制备氧化铬纳米材料的生物模板,提供了一种氧化铬纳米材料的新制备方法。具体以蛋膜为模板,浸渍优化处理后放入反应釜中反应,得到绿色沉淀和茶色膜。沉淀为粒子堆积的形貌单一的微球,产量较多；而蛋膜经热处理后得到暗绿色粉末,形貌为纤维网状结构,纤维由氧化铬粒子堆积而成,其中氧化铬粒子直径在100nm左右,并具有粒径均匀,分散性好等特点,可应用于气敏传感器。(The invention provides a preparation method of a biological template of nano chromium oxide and application of the biological template in gas-sensitive sensing. The present invention uses egg membrane as template and Cr (NO) 3 ) 3 ·9H 2 O is taken as a raw material, and a biological template of the chromium oxide nano material is prepared by adopting a method combining a solvothermal method and a template method, thereby providing a new preparation method of the chromium oxide nano material. Specifically, the egg membrane is taken as a template, and is placed into a reaction kettle for reaction after dipping optimization treatment, so that green precipitate and a brown membrane are obtained. The sediment is the microsphere with single particle accumulation appearance, and the yield is high; the egg membrane is subjected to heat treatment to obtain dark green powder, the shape of the egg membrane is a fiber mesh structure, the fibers are formed by stacking chromium oxide particles, the diameter of each chromium oxide particle is about 100nm, and the egg membrane has the characteristics of uniform particle size, good dispersibility and the like and can be applied to a gas sensor.)

1. A preparation method of a biological template of nano chromium oxide is characterized by comprising the following steps:

s1, placing fresh eggshells in distilled water for ultrasonic treatment for 1 hour, soaking the eggshells in dilute hydrochloric acid until a large number of bubbles are blown out of the eggshells and the eggshells gradually soften, taking out the eggshells, peeling the eggshells to obtain an eggshell membrane, soaking and washing the eggshell membrane in distilled water, and performing ultrasonic treatment;

s2, weighing Cr (NO)₃)₃·9H₂Dissolving O solid powder in ethanol to obtain Cr (NO)₃)₃Ethanol solution;

s3, placing the egg membrane into Cr (NO)₃)₃Soaking in ethanol solution until it turns green, placing the ethanol solution and the original solution into a reaction kettle, placing the reaction kettle in an oven for reaction, cooling to room temperature after the reaction kettle is finished, wherein the reaction kettle is obviously layered, the upper layer is yellow clear liquid, and the lower layer is precipitate and egg membrane;

s4, placing and treating the sediment prepared in the step S3 and the egg membrane separately, rinsing the sediment on the egg membrane with ethanol, placing the sediment and the sediment obtained in the step S3 together, washing and centrifuging the sediment, and drying the sediment at the temperature of 60 ℃.

2. The method for preparing biological templates of nano-chromium oxide according to claim 1, wherein in step S2, said Cr (NO) is₃)₃The concentration of the ethanol solution is 0.025 mol/L.

3. The method for preparing biological templates of nano-chromium oxide according to claims 1-2, wherein in step S3, the Cr (NO) is added₃)₃The dosage of the ethanol solution is 20-30 mL.

4. The method for preparing biological templates of nano-chromium oxide according to claim 3, wherein in step S3, said Cr (NO) is₃)₃The amount of ethanol solution used is preferably 25 mL.

5. The method for preparing the biological template of nano chromium oxide according to claim 1, wherein in the step S3, the soaking time is 12-36 h.

6. The method for preparing the biological template of nano chromium oxide according to claim 5, wherein in the step S3, the soaking time is preferably 12 h.

7. The method for preparing biological templates of nano chromium oxide according to claim 1, wherein in step S3, the reaction conditions are preferably 220 ℃ for 2 h.

8. The biological template of nano chromium oxide prepared by the method of claim 1, wherein the biological template of nano chromium oxide is applicable to a gas sensor.

9. The biological template of nano chromium oxide according to claim 8, which is particularly used for detecting acetone gas, and the detection limit can reach 1.0 ppm.

Technical Field

The invention belongs to the preparation of a chromium oxide nano material, and particularly relates to a preparation method of a biological template of nano chromium oxide and application of the biological template in gas-sensitive sensing.

Background

Chromium belongs to a first transition series element, and oxides with different valence states exist, wherein chromium oxide (Cr) can exist stably₂O₃) Chromium dioxide (CrO)₂) And chromium trioxide (CrO)₃I.e. chromic anhydride), of which trivalent oxide (Cr) is present₂O₃) Due to its special characteristicsThe performance becomes the hot research of materials science.

The nanometer chromium oxide is an important inorganic pigment, has the characteristics of heat resistance, light resistance, corrosion resistance and the like, has magnetism and high hardness, can be used as an abrasive, a polishing agent, a magnetic material and a magnetic recording material, and can be used for catalytic synthesis of amorphous powder. In addition, chromium oxide also plays an important role in the field of catalytic combustion. Therefore, the chromium oxide nano material has wide prospect in practical application.

The chromium oxide nano material is a very important transition metal oxide material, and has the characteristics of heat resistance, light resistance, corrosion resistance and the like, and has magnetism and high hardness, so that the chromium oxide nano material plays an important role in the fields of grinding agents, polishing agents, magnetic materials, magnetic recording materials, organic synthesis catalysis and catalytic combustion.

Chromium oxide also has certain special properties and applications, such as: when the average particle diameter of the chromium oxide fine particles is less than 200nm, the transparency thereof is significantly increased, and when the average particle diameter is less than 50nm, the chromium oxide fine particles can be used as a transparent pigment; in addition, the material has good fluidity and easy uniform distribution, and has important application in high technology, and in addition, the chromium oxide is an excellent photocatalytic material in theory.

In order to obtain nanomaterials, many new synthetic methods have been proposed, and many conventional methods have been improved to some extent, such as various wet chemical methods, templating methods, physical and chemical vapor deposition, electrochemical deposition, electrospinning techniques, pulsed laser deposition, molecular beam epitaxy methods, and the like.

The hydrothermal method refers to a series of chemical and physical reactions carried out in a high-temperature and high-pressure aqueous solution, and the preparation conditions are harsh, and generally, a soluble salt solution of a required metal element is mixed with an alkaline solution, then, the hydrothermal reaction is carried out under the high-temperature and high-pressure conditions, and then, a sample after the hydrothermal reaction is subjected to heat treatment, so that product powder can be obtained. The solvent thermal synthesis method is a method for preparing powder by using an organic solvent to replace water as a medium and adopting a principle similar to hydrothermal synthesis. In the solvothermal synthesis method, the non-aqueous solvent is used as a medium for transferring pressure and also serves as a mineralized substance. The method has the defects of high requirement on equipment, complex operation, high energy consumption, high cost and the like.

The invention combines a biological template method and a solvothermal method to prepare the chromium oxide nano material, and aims to overcome the defects of a single method, reduce the cost, simplify the operation and ensure that the processing of the chromium oxide nano material is easy to industrialize.

Disclosure of Invention

The invention aims to improve the prior art and provides a method for preparing a chromium oxide nano material by combining a biological template method and a solvothermal method.

The technical scheme of the invention is as follows:

a preparation method of a biological template of nano chromium oxide specifically comprises the following steps:

s1, placing fresh eggshells in distilled water for ultrasonic treatment for 1 hour, soaking the eggshells in dilute hydrochloric acid until a large number of bubbles are blown out of the eggshells and the eggshells gradually soften, taking out the eggshells, peeling the eggshells to obtain an eggshell membrane, soaking and washing the eggshell membrane in distilled water, and performing ultrasonic treatment;

s2, weighing Cr (NO)₃)₃·9H₂Dissolving O solid powder in ethanol to obtain Cr (NO)₃)₃Ethanol solution;

s3, placing the egg membrane into Cr (NO)₃)₃Soaking in ethanol solution until it turns green, placing the ethanol solution and the original solution into a reaction kettle, placing the reaction kettle in an oven for reaction, cooling to room temperature after the reaction kettle is finished, wherein the reaction kettle is obviously layered, the upper layer is yellow clear liquid, and the lower layer is precipitate and egg membrane;

s4, placing and treating the sediment prepared in the step S3 and the egg membrane separately, rinsing the sediment on the egg membrane with ethanol, placing the sediment and the sediment obtained in the step S3 together, washing and centrifuging the sediment, and drying the sediment at 60 ℃.

Further, in the step S2, Cr (NO)₃)₃The concentration of the ethanol solution is 0.025 mol/L.

Further, in the step S3, the Cr (NO) is₃)₃The amount of the ethanol solution is 20-30mL, preferably 25 mL.

Further, in the step S3, the soaking time is 12 to 36 hours, preferably 12 hours.

Further, in the step S3, the reaction condition is preferably at 220 ℃ for 2 h.

As shown in fig. 1, is an SEM electron micrograph of the reacted egg membrane prepared according to the present invention, which is a fibrous lattice structure formed by the adsorption of nano chromium oxide particles on the egg membrane, wherein the nano-tubes of chromium oxide form a lattice.

FIG. 2 shows an SEM image of the final precipitate prepared by the present invention, wherein FIG. 2(a) shows a single-morphology nanoparticle with a diameter of 200-500 nm; FIG. 2(b) shows ultrafine chromium oxide particles having a particle diameter of about 100 nm.

As shown in figure 3, the infrared spectrum of the egg membrane and the sediment of the final product prepared by the invention is shown. As can be seen from the figure, the thickness is 3000-3500 cm^-1Wide absorption band and 1626cm^-1The position is xerogel physically adsorbing water hydroxyl O-H stretching vibration and bending vibration and is 500-650 cm^-1Being a characteristic single peak of the Cr-O bond of the chromium oxide, the pure phase chromium oxide should be essentially bimodal, indicating the presence of organic components in the sample.

The invention also aims to provide application of the biological template of the nano chromium oxide in gas-sensitive sensing.

The chromium oxide nano material prepared by the method can be used for preparing a gas sensor, particularly for measuring acetone gas, and the detection limit of the sensor for detecting acetone is 1.0 ppm.

As shown in fig. 4, the sensitivity values of the gas sensor made of the nano chromium oxide prepared by the invention for detecting five different gases of 100ppm are shown. It can be seen from the figure that the gas sensor prepared from the nano chromium oxide has better sensitivity to acetone and ethanol gas, and can be used for measuring acetone gas.

FIG. 5 is a sensitivity curve of a gas sensor made of the chromium oxide nanomaterial prepared by the present invention for detecting acetone gas. As can be seen from the figure, the sensitivity of the gas sensor increases with the increase of the concentration of the acetone gas, the linear detection range of the gas sensor for detecting the acetone gas is 1-10ppm, and the detection limit is 1.0 ppm.

The present invention uses egg membrane as template and Cr (NO)₃)₃·9H₂O is taken as a raw material, and a biological template of the chromium oxide nano material is prepared by adopting a method combining a solvothermal method and a template method, thereby providing a new preparation method of the chromium oxide nano material. Specifically, the egg membrane is taken as a template, and is placed into a reaction kettle for reaction after dipping optimization treatment, so that green precipitate and a brown membrane are obtained. The sediment is the microsphere with single particle accumulation appearance, and the yield is high; the egg membrane is subjected to heat treatment to obtain dark green powder with a fiber mesh structure, and the fibers are made of Cr₂O₃The particles are stacked.

The invention has the beneficial effects that:

(1) the method for preparing the chromium oxide nano material by combining the solvothermal method and the template method is simple and easy to implement, has lower cost and is suitable for industrialization.

(2) The chromium oxide nano material prepared by the invention has the advantages of uniform particle size, good dispersibility, high uniformity and the like, and can be widely applied to the fields of photocatalysis, functional materials and the like.

(3) The chromium oxide nano material prepared by the method can be prepared into a gas sensor and can be used for measuring gases such as acetone and the like.

Drawings

The invention is further illustrated by means of the attached drawings, but the embodiments in the drawings do not constitute any limitation to the invention, and for a person skilled in the art, other drawings can be obtained on the basis of the following drawings without inventive effort.

FIG. 1 is an SEM image of reacted egg membrane prepared according to the present invention;

FIG. 2 is an SEM image of a final precipitate prepared by the present invention;

FIG. 3 is an infrared spectrum of the egg membrane and sediment of the final product prepared by the present invention;

FIG. 4 shows the sensitivity values of a gas sensor made of the chromium oxide nanomaterial prepared by the present invention for detecting five different gases;

FIG. 5 is a sensitivity curve of a gas sensor made of the chromium oxide nanomaterial prepared by the present invention for detecting acetone gas.

Detailed Description

In order that the objects, aspects and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the following detailed description and the accompanying drawings.

Example 1

Preparing a biological template of the chromium oxide nano material:

s1, placing fresh eggshells in distilled water for ultrasonic treatment for 1 hour, soaking the eggshells in dilute hydrochloric acid until a large number of bubbles are blown out of the eggshells and the eggshells gradually soften, taking out the eggshells, peeling the eggshells to obtain an eggshell membrane, soaking and washing the eggshell membrane in distilled water, and performing ultrasonic treatment;

s2, accurately weighing 1.000g of Cr (NO)₃)₃·9H₂Dissolving O solid powder in ethanol to obtain 0.025mol/L Cr (NO)₃)₃Ethanol solution;

s3, placing the egg membrane into 25mL of the prepared Cr (NO)₃)₃After the egg membrane is soaked in the ethanol solution for 12 hours, putting the egg membrane and the original solution into a reaction kettle, putting the reaction kettle into a drying oven for reaction, setting the temperature at 220 ℃ for 2 hours, after the reaction kettle is cooled to room temperature, opening the reaction kettle, and finding that obvious layering exists in the reaction kettle, the upper layer is yellow clear liquid, the lower layer is a precipitate and an egg membrane, wherein the precipitate is dark green, the membrane is dark brown, the precipitate is mostly attached to the membrane, and a small amount of precipitate also exists on the kettle wall and the kettle bottom;

s4, placing and treating the prepared sediment and the egg membrane separately, rinsing the sediment on the egg membrane with ethanol, placing the sediment and the obtained sediment together, washing and centrifuging the obtained sediment, and drying the sediment at the temperature of 60 ℃.

The morphology of the egg membrane and the precipitate finally obtained as described above was measured by a scanning electron microscope of model S-4800 manufactured by HITACHI, Japan. Setting the test voltage at 5KV and 10KV, ultrasonically dispersing the sample to be tested in ethanol before testing, and dropping the sample on an aluminum foil for testing to obtain the attached figures 1 and 2.

Infrared spectroscopy was carried out using an EQUINOX model 55 from BrukerAnd (4) qualitatively analyzing the finally obtained egg membrane and precipitate by adopting a potassium bromide tabletting method. Test resolution of 0.5cm^-1The scanning range is as follows: 4000-350cm^-1The number of scans was 10, yielding figure 3.

Example 2

Preparing a biological template of the chromium oxide nano material:

s1, placing fresh eggshells in distilled water for ultrasonic treatment for 1 hour, soaking the eggshells in dilute hydrochloric acid until a large number of bubbles are blown out of the eggshells and the eggshells gradually soften, taking out the eggshells, peeling the eggshells to obtain an eggshell membrane, soaking and washing the eggshell membrane in distilled water, and performing ultrasonic treatment;

s2, accurately weighing 1.000g of Cr (NO)₃)₃·9H₂Dissolving O solid powder in ethanol to obtain 0.025mol/L Cr (NO)₃)₃Ethanol solution;

s3, placing the egg membrane into 20mL of the prepared Cr (NO)₃)₃After the egg membrane is soaked in the ethanol solution for 12 hours, putting the egg membrane and the original solution into a reaction kettle, putting the reaction kettle into a drying oven for reaction, setting the temperature at 220 ℃ for 2 hours, after the reaction kettle is cooled to room temperature, opening the reaction kettle, and finding that obvious layering exists in the reaction kettle, the upper layer is yellow clear liquid, the lower layer is a precipitate and an egg membrane, wherein the precipitate is dark green, the membrane is dark brown, the precipitate is mostly attached to the membrane, and a small amount of precipitate also exists on the kettle wall and the kettle bottom;

s4, placing and treating the prepared sediment and the egg membrane separately, rinsing the sediment on the egg membrane with ethanol, placing the sediment and the obtained sediment together, washing and centrifuging the obtained sediment, and drying the sediment at the temperature of 60 ℃.

Example 3

Preparing a biological template of the chromium oxide nano material:

s1, placing fresh eggshells in distilled water for ultrasonic treatment for 1 hour, soaking the eggshells in dilute hydrochloric acid until a large number of bubbles are blown out of the eggshells and the eggshells gradually soften, taking out the eggshells, peeling the eggshells to obtain an eggshell membrane, soaking and washing the eggshell membrane in distilled water, and performing ultrasonic treatment;

s2, accurately weighing 1.000g of Cr (NO)₃)₃·9H₂Dissolving O solid powder in ethanol to obtain 0.025mol/L Cr (NO)₃)₃Ethanol solution;

s3, placing the egg membrane into 30mL of the prepared Cr (NO)₃)₃After the egg membrane is soaked in the ethanol solution for 12 hours, putting the egg membrane and the original solution into a reaction kettle, putting the reaction kettle into a drying oven for reaction, setting the temperature at 220 ℃ for 2 hours, after the reaction kettle is cooled to room temperature, opening the reaction kettle, and finding that obvious layering exists in the reaction kettle, the upper layer is yellow clear liquid, the lower layer is a precipitate and an egg membrane, wherein the precipitate is dark green, the membrane is dark brown, the precipitate is mostly attached to the membrane, and a small amount of precipitate also exists on the kettle wall and the kettle bottom;

s4, placing and treating the prepared sediment and the egg membrane separately, rinsing the sediment on the egg membrane with ethanol, placing the sediment and the obtained sediment together, washing and centrifuging the obtained sediment, and drying the sediment at the temperature of 60 ℃.

Example 4

Preparing a biological template of the chromium oxide nano material:

s1, placing fresh eggshells in distilled water for ultrasonic treatment for 1 hour, soaking the eggshells in dilute hydrochloric acid until a large number of bubbles are blown out of the eggshells and the eggshells gradually soften, taking out the eggshells, peeling the eggshells to obtain an eggshell membrane, soaking and washing the eggshell membrane in distilled water, and performing ultrasonic treatment;

s2, accurately weighing 1.000g of Cr (NO)₃)₃·9H₂Dissolving O solid powder in ethanol to obtain 0.025mol/L Cr (NO)₃)₃Ethanol solution;

s3, placing the egg membrane into 25mL of the prepared Cr (NO)₃)₃After the egg membrane is soaked in the ethanol solution for 24 hours, putting the egg membrane and the original solution into a reaction kettle, putting the reaction kettle into a drying oven for reaction, setting the temperature at 220 ℃ for 2 hours, after the reaction kettle is cooled to room temperature, opening the reaction kettle, and finding that obvious layering exists in the reaction kettle, the upper layer is yellow clear liquid, the lower layer is a precipitate and an egg membrane, wherein the precipitate is dark green, the membrane is dark brown, the precipitate is mostly attached to the membrane, and a small amount of precipitate also exists on the kettle wall and the kettle bottom;

s4, placing and treating the prepared sediment and the egg membrane separately, rinsing the sediment on the egg membrane with ethanol, placing the sediment and the obtained sediment together, washing and centrifuging the obtained sediment, and drying the sediment at the temperature of 60 ℃.

Example 5

Preparing a biological template of the chromium oxide nano material:

s1, placing fresh eggshells in distilled water for ultrasonic treatment for 1 hour, soaking the eggshells in dilute hydrochloric acid until a large number of bubbles are blown out of the eggshells and the eggshells gradually soften, taking out the eggshells, peeling the eggshells to obtain an eggshell membrane, soaking and washing the eggshell membrane in distilled water, and performing ultrasonic treatment;

s2, accurately weighing 1.000g of Cr (NO)₃)₃·9H₂Dissolving O solid powder in ethanol to obtain 0.025mol/L Cr (NO)₃)₃Ethanol solution;

s3, placing the egg membrane into 25mL of the prepared Cr (NO)₃)₃After the egg membrane is soaked in the ethanol solution for 36 hours, putting the egg membrane and the original solution into a reaction kettle, putting the reaction kettle into a drying oven for reaction, setting the temperature at 220 ℃ for 2 hours, after the reaction kettle is cooled to room temperature, opening the reaction kettle, and finding that obvious layering exists in the reaction kettle, the upper layer is yellow clear liquid, the lower layer is a precipitate and an egg membrane, wherein the precipitate is dark green, the membrane is dark brown, the precipitate is mostly attached to the membrane, and a small amount of precipitate also exists on the kettle wall and the kettle bottom;

s4, placing and treating the prepared sediment and the egg membrane separately, rinsing the sediment on the egg membrane with ethanol, placing the sediment and the obtained sediment together, washing and centrifuging the obtained sediment, and drying the sediment at the temperature of 60 ℃.

Example 6

Preparing and testing the gas sensor:

and mixing and pulping the nano chromium oxide prepared in the embodiment 1, coating the mixture on the surface of a ceramic tube, drying, performing heat treatment, and connecting electrodes and leads at two ends of the ceramic tube to prepare the gas sensor.

Measuring stable resistance R of gas sensor_aPlacing the gas sensor in a test box, introducing gas to be tested,record its stable resistance R_gWith R_g/R_aIs calculated for the sensitivity value.

The gas sensor is used for detecting five gases of 100ppm NO, CO, acetone, formaldehyde and ethanol respectively, and the obtained test result is shown in the attached figure 4. The sensitivity value of the gas sensor increases as the concentration of the test gas increases. The sensitivity values were specifically determined as follows:

under the environment of 220 ℃, the sensitivity curve of the gas sensor in acetone gas with different concentrations is detected, and the gas sensor shown in the attached figure 5, which is prepared from the nano chromium oxide prepared in the embodiment 1, can detect the acetone gas, and the detection limit can reach 1.0 ppm.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single technical solution, and such description is for clarity only, and those skilled in the art should take the description as a whole, and the technical solutions in the embodiments may be combined appropriately to form other embodiments that those skilled in the art can understand. The technical details not described in detail in the present invention can be implemented by any of the prior arts in the field. In particular, all technical features of the invention which are not described in detail can be achieved by any prior art.