阅读说明：本技术 一种对氨气具有高响应的铬修饰空心氧化铟的制备方法 (Preparation method of chromium-modified hollow indium oxide with high response to ammonia gas ) 是由 宋鹏 田哲宾 王�琦 梁栋 于 2019-09-29 设计创作，主要内容包括：本发明提供了一种对氨气具有高响应的铬修饰空心氧化铟的制备方法。该制备方法具体包括：以N-N二甲基甲酰胺,对苯二甲酸,硝酸铬水合物和硝酸铟水合物为原料,经油浴反应、煅烧处理,得到六棱空心盒子结构的氧化铟。多孔结构具有较大的表面积,可以有效吸附更多的氧气和目标气体,空心结构可以有效提高材料的利用率,提高传感性能。因此兼备多孔及空心结构将有助于改善性能。本实验不使用昂贵的表面活性剂,成本比较低,对氨气气体具有良好的气敏性能,因此在氨气气体检测方面具有长远的应用前景。(the invention provides a preparation method of chromium-modified hollow indium oxide with high response to ammonia gas. The preparation method specifically comprises the following steps: N-N dimethylformamide, terephthalic acid, chromium nitrate hydrate and indium nitrate hydrate are used as raw materials, and the indium oxide with the hexagonal hollow box structure is obtained through oil bath reaction and calcination treatment. The porous structure has a larger surface area, can effectively adsorb more oxygen and target gas, and the hollow structure can effectively improve the utilization rate of materials and improve the sensing performance. Thus, having both porous and hollow structures will help improve performance. The experiment does not use expensive surfactant, has lower cost and good gas-sensitive performance to ammonia gas, and thus has long-term application prospect in the aspect of ammonia gas detection.)

1. a preparation method of chromium-modified hollow indium oxide with high response to ammonia gas comprises the following specific synthetic steps:

(1) First, 160 mL of DMF was taken in a 1 clean and dry 250 mL beaker (number 1) with a measuring cylinder and placed in a clean magnetic rotor;

(2) 200 mL of DMF was taken from a graduated cylinder and poured into another clean and dry 250 mL beaker (No. 2);

(3) Accurately weighing 200 mg of chromium nitrate hexahydrate by using an electronic analytical balance, and adding the chromium nitrate hexahydrate into a beaker (No. 2);

(4) accurately weighing 0.05-0.08 g of terephthalic acid and 0.05-0.08 g of indium nitrate hydrate by using an electronic analytical balance, pouring into a beaker (No. 1) filled with DMF, putting the beaker on a magnetic stirrer for stirring, and taking 0.175-2.8 mL of solution from the beaker (No. 2) into the beaker (No. 1) by using a liquid-transferring gun;

(5) putting the beaker with the solute completely dissolved into an oil bath pan for oil bath heating, setting the conditions at 120 ℃, and keeping the temperature for 30-50 min after the temperature is raised to 120 ℃;

(6) Immediately taking out the beaker after heating, standing, cooling, and washing the precipitate;

(7) and uniformly dispersing the dried sample in a dry crucible, and then putting the crucible into a box-type muffle furnace for calcination, wherein the temperature rise rate is controlled to be 1 minute and one degree till 400-500 ℃, the temperature is kept for 3 hours, the temperature drop rate is controlled to be 2-3 ℃ per minute, and the calcination is finished, so that a light yellow powdery sample can be obtained.

Technical Field

the invention relates to a preparation method of chromium-modified hollow indium oxide with high response to ammonia gas, belonging to the technical field of advanced nano functional material preparation processes.

background

in daily life, people are seriously damaged by industrial production waste gas, automobile exhaust, PM2.5 and other gases when going out, and are influenced by toxic gases such as ammonia gas, benzene and the like when going home. Therefore, it is very important to research and develop a high-performance gas sensor, whether the gas sensor is needed for detecting environmental pollution gas or for ensuring quality of life and industrial safety. With the increasing attention of people to the environmental protection problem and the strict monitoring of the emission of toxic and harmful gases, various gas inspection and early warning devices with different functions are developed, and further, the industrialization and the commercialization are achieved. The semiconductor gas sensor has the characteristics of high detection sensitivity, quick response recovery, simple circuit, simplicity in operation, small element size, low price and the like, and is widely applied to various gas detection fields.

in2O3 has a large forbidden band width, a band gap close to GaN, and has the advantages of low resistivity, high sensitivity, low working temperature, low absorbance, high infrared reflectivity and the like In a visible light region. The main factor influencing the performance of the In2O3 nanomaterial is the structural morphology, so currently, many researchers are working on research for controlling the generation of the In2O3 crystal morphology so as to improve the performance of various aspects thereof. In recent years, the application of indium oxide nano materials in the field of photoelectric thin films is successively reported in developed countries in Europe and America. At present, researchers prepare one-dimensional, two-dimensional and three-dimensional In2O3 nano materials by a nano material synthesis method of a gas phase method, a solid phase method and a liquid phase method. The specific shapes of the nano-tube/nano-rod composite material comprise a nano-tube, a nano-wire, a nano-rod, a cube, an octahedron and the like, and the nano-tube/nano-rod composite material is widely applied to the fields of optics, magnetics, electronics, medical treatment and the like. In order to improve the recognition function, in addition to selecting a good matrix material and modifying by doping, compounding and surface modification, designing and preparing porous and hollow structure materials with large specific surface area and high active site density are also interesting strategies. The indium oxide prepared by the method has a porous structure and good permeability, can promote gas diffusion, and is beneficial to improving the utilization rate of a sensitive body. In addition, in order to improve the sensitivity of semiconductor gas sensors, a method of increasing the surface area of a material is often used, and nano-sizing is a common method. The nanocrystallization increases the surface area of the material, so that the height and thickness of the potential barrier on the particle surface and the effective resistance of crystal grains are obviously changed, the surface activity is greatly increased, the adsorption, desorption and redox reactions of the material on gas can be carried out at lower temperature, the working temperature is reduced, the response time is shortened, and the concentration range of gas detection is improved. The research on In2O3 nano materials, particularly the structural morphology thereof, is In the initial stage In China, but the preparation method has the defects of complex operation, high production cost and the like, so that the research result is difficult to be put into the actual industrial production In a large range. In addition, due to the restrictions of experimental equipment and production technology, the research on In2O3 nano materials, especially the research on gas-sensitive performance, is not very deep. Researchers are keenly looking at studying the structural morphology and functional property characteristics of In2O3 nanomaterials In a more systematic and comprehensive perspective.

disclosure of Invention

the invention aims to overcome the defects of the prior art and provide a preparation method of a chromium-doped indium oxide hollow box with a hexagonal structure. Has the characteristics of low cost, simple production process, high yield, no environmental pollution and easy industrialized large-scale production. The sensitivity of the obtained indium oxide gas-sensitive material with the porous structure is greatly improved, and the indium oxide gas-sensitive material can be used in the fields of gas sensors and the like. The technical scheme for realizing the purpose of the invention is as follows: a preparation method of a chromium-doped indium oxide hollow box with a hexagonal structure is characterized by comprising the following steps: indium nitrate, chromium nitrate and terephthalic acid are used as raw materials, and the chromium-doped indium oxide box with a hollow box structure is obtained through hydrothermal reaction and calcination treatment. The method has simple production process, does not use expensive surface active agent, has lower cost, and the obtained indium oxide can be used as a gas-sensitive material and has a hollow structure. Has good gas-sensitive performance to ammonia gas, thereby having long-term application prospect in the aspect of ammonia gas detection. The specific synthesis steps are as follows:

(1) First, 160 mL of DMF was taken in a 1 clean and dry 250 mL beaker (number 1) with a measuring cylinder and placed in a clean magnetic rotor;

(2) 200 mL of DMF was taken from a graduated cylinder and poured into another clean and dry 250 mL beaker (No. 2);

(3) Accurately weighing 200 mg of chromium nitrate hexahydrate by using an electronic analytical balance, and adding the chromium nitrate hexahydrate into a beaker (No. 2);

(4) accurately weighing 0.05-0.08 g of terephthalic acid and 0.05-0.08 g of indium nitrate hydrate by using an electronic analytical balance, pouring into a beaker (No. 1) filled with DMF, putting the beaker on a magnetic stirrer for stirring, and taking 0.175-2.8 mL of solution from the beaker (No. 2) into the beaker (No. 1) by using a liquid-transferring gun;

(5) putting the beaker with the solute completely dissolved into an oil bath pan for oil bath heating, setting the conditions at 120 ℃, and keeping the temperature for 30-50 min after the temperature is raised to 120 ℃;

(6) Immediately taking out the beaker after heating, standing, cooling, and washing the precipitate;

(7) And uniformly dispersing the dried sample in a dry crucible, and then putting the crucible into a box-type muffle furnace for calcining. Wherein the temperature rise rate is controlled to be 1 minute to 400 ℃ plus 500 ℃, the temperature is kept for 3 hours, the temperature reduction system is controlled to be 2-3 ℃ per min, and the light yellow powdery sample can be obtained after the calcination is finished.

Drawings

fig. 1 is a low magnification SEM image of a chromium-doped indium oxide hollow box with a hexagonal prism structure.

fig. 2 is a high power SEM image of a chromium doped indium oxide hollow box with a hexagonal prism structure.

fig. 3 is a high power TEM image of a chromium doped indium oxide hollow box with a hexagonal prism structure.

FIG. 4 is a gas sensitivity graph of gas sensitivity performance of chromium-doped indium oxide hollow boxes with hexagonal structures as a function of ammonia concentration (1-50 ppm).

fig. 5 is a diagram showing the gas sensitivity of the chromium-doped indium oxide hollow box with a hexagonal structure to different gases (1 formaldehyde, 2 acetone, 3 ammonia, 4 methanol, 5 ethanol).

Detailed Description

The following is a detailed description of the embodiments of the present invention, which is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.