阅读说明：本技术 一种对丙酮气体敏感的三维放射状四氧化三钴纳米线团簇 (Three-dimensional radial cobaltosic oxide nanowire cluster sensitive to acetone gas ) 是由 薛庆忠 乔煦容 李小芳 熊雅 常晓 李潇 于 2020-05-06 设计创作，主要内容包括：本发明提供了一种可用于检测低浓度丙酮的三维放射状四氧化三钴(Co-(3)O-(4))纳米线团簇制备方法,属于气体敏感材料技术领域。我们首先通过简单的水热合成法了层状氢氧化钴盐(Co-LHMS),随后以Co-LHMS为自模板,在高温下煅烧得到具有相应结构的四氧化三钴(Co-(3)O-(4))。通过调整水热反应时间,我们可以得到具有薄片花状、三维放射状和哑铃放射状三种结构的Co-LHMS前驱体。对比相应结构的Co-(3)O-(4)发现,三维放射状Co-(3)O-(4)在200℃时对低浓度丙酮的敏感性最高,其对100ppb丙酮的响应值可以达到1.15。因此,此方法不仅制备简单,原料成本低,可重复性好,同时能够有效解决一维Co-(3)O-(4)的堆积问题,对低浓度丙酮具有良好的敏感性,具有很好的应用价值和前景。(The invention provides three-dimensional radial cobaltosic oxide (Co) for detecting low-concentration acetone 3 O 4 ) A preparation method of nanowire clusters belongs to the technical field of gas sensitive materials. Firstly, layered cobalt hydroxide salt (Co-LHMS) is synthesized by a simple hydrothermal synthesis method, and then the Co-LHMS is taken as a self-template to be calcined at high temperature to obtain cobaltosic oxide (Co-LHMS) with a corresponding structure 3 O 4 ). By adjusting the hydrothermal reaction time, the Co-LHMS precursor with three structures of thin flower shape, three-dimensional radial shape and dumbbell radial shape can be obtained. Comparison of Co of corresponding structures 3 O 4 It was found that three-dimensionally radial Co 3 O 4 The sensitivity to low-concentration acetone is highest at 200 ℃, and the response value to 100ppb acetone can reach 1.15. Due to the fact thatThe method has the advantages of simple preparation, low raw material cost and good repeatability, and can effectively solve the problem of one-dimensional Co 3 O 4 The problem of accumulation is solved, and the method has good sensitivity to low-concentration acetone and good application value and prospect.)

1. A three-dimensional radial cobaltosic oxide nanowire cluster sensitive to acetone gas and a preparation method thereof are disclosed, wherein the preparation method comprises the following steps:

(1) adding a certain amount of cobalt nitrate hexahydrate into ultrapure water, and stirring for 30 minutes until the cobalt nitrate hexahydrate is fully dissolved;

(2) adding a certain amount of urea into ultrapure water, and stirring for 30 minutes until the urea is fully dissolved;

(3) fully mixing the solutions obtained in the step (1) and the step (2), and stirring for 5 minutes at room temperature;

(4) and (4) transferring the mixed solution obtained in the step (3) into a high-temperature reaction kettle, and carrying out hydrothermal reaction for 4 hours at 105 ℃.

(5) The product obtained in step (4) was washed with deionized water by multiple centrifugation, after which the product was dried in vacuo overnight at 60 ℃.

(6) And (4) moving the completely dried sample obtained in the step (5) into a crucible, placing the crucible into a tube furnace, calcining the sample at 300 ℃ for 2 hours, taking out the sample, coating the final product on a test electrode, placing the test electrode into a clean environment for storage, and waiting for a subsequent acetone sensitivity performance test.

Adjusting the hydrothermal reaction time in the step (4) to 2 hours and 12 hours to respectively obtain Co-LHMS with a flake flower-shaped structure and a dumbbell radial structure, and calcining to obtain Co with a corresponding structure₃O₄。

Technical Field

The present invention belongs to the field of gas sensitive material technologyA three-dimensional radial cobaltosic oxide (Co)₃O₄) Preparation of nanowire clusters and research on gas-sensitive performance of the nanowire clusters to acetone.

Background

Acetone (C)₃H₆O) has wide applications in industry, agriculture and daily life, however acetone gas is a toxic and harmful gas and has many adverse effects on health in an environment containing acetone for a long time. Meanwhile, acetone is used as a biomarker for diagnosing diabetes in the medical field, wherein the concentration of acetone in expired breath of a diabetic patient is higher than 1.8ppm, and the concentration of acetone in expired breath of a healthy person is about 0.3 ppm. Therefore, the detection of trace acetone has important application significance and prospect in the fields of environmental monitoring, diabetes diagnosis and the like. In recent years, Metal Oxide Semiconductors (MOS) have become a hot research point for acetone-sensitive materials due to their advantages of low price, small size, and convenient operation.

Cobaltosic oxide (Co)₃O₄) Is a typical p-type MOS, has good selective catalytic activity on reducing gas, and is expected to be used in the field of acetone sensing. At present, one-dimensional Co₃O₄Has received a great deal of attention due to the effects of having a large specific surface area and radial dimensions. For example, Cao et al synthesized Co with a hierarchical structure₃O₄Nanofibers that respond to 100ppm acetone at a working temperature of 190 ℃ of 9.3(The Journal of Physical Chemistry B,2006,110(32): 15858-15863); wang et al found that at 200 deg.C, the surface was rough and porous rectangular Co₃O₄The nanorods responded to 5ppm acetone (Sensors and activators B: Chemical,297 (2019)). However, commonly used one-dimensional material synthesis methods, such as direct hydrothermal or electrospinning, may result in agglomeration or structural collapse, thereby preventing one-dimensional Co₃O₄Detection of ultra low concentration acetone. Therefore, a new solution to one-dimensional Co is needed₃O₄Disadvantages in the synthesis process.

The three-dimensional radial structure can solve agglomeration and collapse while maintaining the performance of a one-dimensional materialAnd (5) problems are solved. Wherein, the three-dimensional radial layered metal hydroxide salt (LHMS) has a unique layered crystal structure, and the layered cobalt hydroxide salt (Co-LHMS) is used as a self-template by a calcination method, so that the structure can be maintained and simultaneously the layered cobalt hydroxide salt (Co-LHMS) is converted into Co with rough surface and rich pores₃O₄(Journal of Materials Chemistry,2005,15(19): 1938). However, the three-dimensional radial Co-LHMS nanowire cluster (three-dimensional radial Co-LHMS for short, the same applies below) is taken as a self-template to synthesize Co₃O₄The use for acetone detection is rarely reported.

In contrast, the three-dimensional radial Co-LHMS precursor is synthesized by taking cobalt salt as a raw material and adopting a simple direct hydrothermal method. The precursor is pyrolyzed by calcining in a tube furnace to obtain three-dimensional radial Co with a large number of pore passages and a rough surface₃O₄Nanowire cluster (three-dimensional radial Co for short)₃O₄The same applies below). The results show that the material has excellent sensitivity to ultra-low concentration acetone. The method is simple to operate, low in raw material cost and environment-friendly, the sensitivity of the product to the ultra-low concentration acetone is high, a new idea for solving the problem of one-dimensional material agglomeration is provided, and the method has good application value and prospect.

Disclosure of Invention

The invention aims to provide a preparation method of a three-dimensional radial acetone sensitive material. Synthesizing a three-dimensional radial Co-LHMS precursor by a direct hydrothermal method, and preparing the three-dimensional radial Co by a pyrolysis method₃O₄. The preparation method has the characteristics of low cost, convenient operation, simplicity, rapidness and the like.

Cobalt nitrate hexahydrate (Co (NO) is used below₃)₂·6H₂O) is an example to briefly explain the implementation process of the present invention. Firstly, synthesizing a three-dimensional radial Co-LHMS precursor by a hydrothermal method, putting the precursor into a crucible after a product is completely dried, and then putting the crucible into a tubular furnace for heat treatment in an air atmosphere at 300 ℃. And storing the prepared sample in a clean environment, and waiting for a subsequent acetone sensitivity performance test. The three-dimensional radial Co₃O₄The method can be realized by the following specific steps:

(1) adding a certain amount of cobalt nitrate hexahydrate into ultrapure water, and stirring for 30 minutes until the cobalt nitrate hexahydrate is fully dissolved;

(2) adding a certain amount of urea into ultrapure water, and stirring for 30 minutes until the urea is fully dissolved;

(3) fully mixing the solutions obtained in the step (1) and the step (2), and stirring for 5 minutes at room temperature;

(4) and (4) transferring the mixed solution obtained in the step (3) into a high-temperature reaction kettle, and carrying out hydrothermal reaction for 4 hours at 105 ℃.

(5) The product obtained in step (4) was washed with deionized water by multiple centrifugation, after which the product was dried in vacuo overnight at 60 ℃.

(6) And (4) moving the completely dried sample obtained in the step (5) into a crucible, placing the crucible into a tube furnace, calcining the sample at 300 ℃ for 2 hours, taking out the sample, coating the final product on a test electrode, placing the test electrode into a clean environment for storage, and waiting for a subsequent acetone sensitivity performance test.

Adjusting the hydrothermal reaction time in the step (4) to 2 hours and 12 hours to respectively obtain Co-LHMS with a flake flower-shaped structure and a dumbbell radial structure, and calcining to obtain Co with a corresponding structure₃O₄。

Co comparing the above different structures₃O₄Acetone sensitivity can be found. When the working temperature is 200 ℃, three-dimensional radial Co₃O₄The response was best for low concentrations of acetone, which corresponds to a value of 1.15 for 100ppb acetone. Meanwhile, the three-dimensional radial Co₃O₄The acetone gas-sensitive property has good stability.

The invention provides a method for preparing three-dimensional radial Co₃O₄Can maintain one-dimensional Co₃O₄The excellent performance solves the agglomeration problem in the conventional synthesis process. Three-dimensional radial Co obtained by the method₃O₄Sensitivity to low concentrations of acetone. Meanwhile, the method is simple to prepare, low in raw material cost, good in repeatability and good in application value and prospect.

Drawings

FIG. 1 is a scanning electron microscope image of thin flower, three-dimensional radial and dumbbell radial Co-LHMS.

FIG. 2 shows thin flower-like, three-dimensional radial and dumbbell-like Co₃O₄Scanning electron microscopy of (a).

FIG. 3 shows thin flower-like, three-dimensional radial and dumbbell-like Co concentrations at 200 ℃ of 100ppb, 250ppb, 500ppb, 750ppb and 1000ppb for acetone concentration, respectively₃O₄Graph of response values as a function of acetone on/off.

FIG. 4 shows three-dimensional radial Co at 200 deg.C₃O₄The cycle test was responded to 20ppm acetone.

Detailed Description

The present invention is described in detail below with reference to the drawings and examples.

Example 1 2.017 grams of cobalt nitrate hexahydrate was added to 15ml of ultra pure water and stirring was continued for 30 minutes until the inorganic salts were completely dissolved. 0.045 g of urea was dissolved in 15ml of ultrapure water and stirring was continued for 30 minutes. The cobalt nitrate hexahydrate solution was then added to the urea solution, mixed thoroughly and stirred for 5 minutes. The mixed solution was transferred to a high-temperature reaction vessel having a capacity of 50 ml, and reacted at 105 ℃ for 2 hours, 4 hours and 12 hours, respectively. The resulting product was washed with deionized water several times, and then the centrifuged product was dried under vacuum for 12 hours. And after the sample is fully dried, placing the sample in a tubular furnace, calcining the sample for 2 hours at 300 ℃ in an air atmosphere, and taking the sample out, wherein the heating rate is 1 ℃ per minute. And (3) taking a proper amount of sample to disperse in deionized water, then dripping the dispersion on a test electrode, drying at 60 ℃ for 2 hours, and then carrying out an acetone sensitivity performance test.

FIG. 1 shows scanning electron micrographs of Co-LHMS precursors obtained at different hydrothermal reaction times, respectively. From FIG. 1(a), it can be seen that the sample with the hydrothermal reaction time of 2 hours has a flake-like morphology; it can be seen in FIG. 1(b) that the morphology of the sample at 4 hours reaction time is three-dimensional radial with a diameter of about 10 microns; in FIG. 1(c), it can be seen that the morphology of the sample at a reaction time of 12 hours is dumbbell-shaped.

FIG. 2 shows a flower-like three-dimensional arrangement of thin sheetsCo obtained by calcining radial and dumbbell radial Co-LHMS serving as precursor₃O₄It can be seen that Co-LHMS is taken as a self-template to synthesize Co₃O₄The structure of the sample hardly changes.

FIG. 3 shows the Co in the form of flakes, three-dimensional radial and dumbbell in the case of acetone concentrations of 100ppb, 250ppb, 500ppb, 750ppb and 1000ppb, respectively, at 200 ℃₃O₄Graph of response values as a function of acetone on/off. As can be seen from the figure, the three-dimensional radial Co₃O₄The response value to low-concentration acetone is higher than that of thin flower-shaped and dumbbell-shaped radial Co₃O₄. Wherein the three-dimensional radial shape Co₃O₄The value corresponds to 1.15 for 100ppb acetone.

FIG. 4 shows three-dimensional radial Co at 200 deg.C₃O₄Cycle test curves were responded to 20ppm acetone. As can be seen, after undergoing the multi-test cycle test, the three-dimensional radial Co₃O₄The response value of (A) can still be restored to the initial state, and the response value is hardly changed, which shows that the sensitivity of the product to acetone is very stable.

Wherein the response value is calculated by the resistance of the sample under different atmosphere conditions, and the calculation formula is as follows: r ═ S_g/R_a(ii) a Wherein R is_gIs the resistance of the material in an acetone atmosphere, R_aIs the electrical resistance of the material under air.