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Preparation method of ethanol gas sensor element with ultrafast response recovery characteristics

A gas sensor and component technology, applied in nanotechnology, nanotechnology, nanotechnology, etc. for materials and surface science, can solve problems such as unfavorable low-power device research, inability to achieve real-time monitoring, and long response recovery time. Achieving the effect of multiple reactive active sites, reduced response recovery time, and fast response recovery

Inactive Publication Date: 2017-10-24
TAIYUAN UNIV OF TECH
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  • Abstract
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Problems solved by technology

However, based on the previous research work of scientific researchers, it was found that: (1) LaFeO 3 The resistance itself is very large, which is not conducive to practical application. Ca, Sr, Ba, Pb and other divalent elements are often doped to replace the position of trivalent La, or doped with Co, Mg, Ni and other elements to replace the position of trivalent Fe, providing More hole carriers, thereby reducing the resistance of the material; (2) LaFeO with higher sensitivity 3 For ethanol-based gas sensor components, the optimal operating temperature is still high, usually above 200 °C, which is not conducive to the research of low-power devices; LaFeO with an optimal operating temperature below 200 °C 3 The ethanol-based gas sensor element either contains heavy metal elements such as Pb, which is not conducive to environmental protection, or contains rare earth precious metals such as Sm, and the cost is relatively high; (3) the current LaFeO 3 The response time of the base ethanol gas sensor element is usually above 10s, and the recovery time is above 15s. The response recovery time is long, and the purpose of real-time monitoring cannot be achieved.

Method used

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  • Preparation method of ethanol gas sensor element with ultrafast response recovery characteristics
  • Preparation method of ethanol gas sensor element with ultrafast response recovery characteristics
  • Preparation method of ethanol gas sensor element with ultrafast response recovery characteristics

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preparation example Construction

[0029] The preparation method of the ethanol gas sensor element with ultra-fast response recovery characteristics has the following steps:

[0030] (1) Precursor ingredients

[0031] Accurately weigh La(NO 3 ) 3 · 9H 2 O and Fe(NO 3 ) 3 ·6H 2 O;

[0032] (2) Preparation of xerogel

[0033] Dissolve the precursor ingredients in deionized water, add citric acid to form a mixed solution according to the molar ratio of the sum of cations and citric acid at 1:2, and place the mixed solution at 70-80°C (70°C, 72°C, 74°C can be selected , 76°C, 78°C, 80°C) and stir in a water bath, add polyethylene glycol PEG-6000 at a molar ratio of 1:200 to the sum of cations to form a sol, and continue stirring until the dry gel state;

[0034] (3) LaFe x o 3 Preparation of Nanopowder

[0035] Put the dry gel into the crucible to heat to remove the organic matter, put the obtained powder into the muffle furnace after grinding, and sinter at 590-610°C (590°C, 600°C, 610°C can be selected...

Embodiment 1

[0040] (1) Precursor ingredients

[0041] According to the stoichiometric ratio La:Fe=1:0.8, accurately weigh 0.03mol of La(NO 3 ) 3 · 9H 2 O and 0.024mol Fe(NO 3 ) 3 ·6H 2 O;

[0042] (2) Preparation of xerogel

[0043] Dissolve the precursor ingredients in deionized water, add 0.054mol citric acid according to the molar ratio of the sum of cations and citric acid being 1:2, place the mixed solution in a water bath at 80°C, stir and add 2g polyethylene glycol to form a sol, Continue to stir until the dry gel state;

[0044] (3) LaFe 0.8 o 3 Preparation of Nanopowder

[0045] Put the dry gel into the crucible to heat to remove the organic matter, put the obtained powder into the muffle furnace after grinding, and sinter at 590-610°C for 2 hours to obtain the LaFe 0.8 o 3 Powder grain size is about 25nm;

[0046] (4) Preparation of side-heated ceramic tube structure gas sensor element

[0047] Take 0.1g of LaFe 0.8 o 3 Put the powder in an agate mortar, add 0.02...

Embodiment 2

[0050] The difference between this example and Example 1 is that in step (1), the stoichiometric ratio La:Fe=1:0.7 is used for batching, and the obtained nano-scale LaFe 0.7 o 3 The powder grain size is about 20nm, and the LaFe 0.7 o 3 The side-heated ceramic tube gas sensor element has good selectivity to ethanol, the best working temperature and response recovery time remain unchanged, and the sensitivity to 1000ppm ethanol is 95, compared with LaFe 0.8 o 3 Gas sensor elements are somewhat lower, but still better than LaFeO 3 55 high for the gas sensor element.

[0051] The present invention adopts static gas distribution method to measure non-stoichiometric ratio LaFe x o 3 Nanoparticles are the sensitive characteristics of the gas sensor element as the working substance to ethanol gas. The sensitivity of the gas sensor element is defined as S = Rg / Ra, where Rg and Ra represent the resistance value of the element in the gas to be measured and dry air respectively; the...

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Abstract

The invention discloses a method for preparing an ethanol gas sensor element with ultra-fast response and recovery characteristics. The non-stoichiometric ratio LaFexO3 nanoparticles prepared by the sol-gel method are selected as the working material, and the side-heating ceramic tube gas sensor element is prepared. . By reducing the relative element ratio of Fe to La in the precursor, increasing the carrier concentration and reducing the element resistance; choosing an appropriate La / Fe element ratio, reducing the grain size and increasing the ability to absorb oxygen, thereby improving the sensitivity to ethanol , Reduce the working temperature, reduce the response recovery time. Utilize the LaFe0.8O3 side heating type gas sensor element prepared by the present invention under the working temperature of 140 ℃, the sensitivity to 1000ppm ethanol can reach 138, the response and recovery time are respectively 1s and 1.5s, to 1000ppm methane, acetone, carbon dioxide and The sensitivity of glycerol is below 22, and it has high sensitivity, low working temperature, ultra-fast response and recovery characteristics and high selectivity to ethanol, and has the advantages of low cost and environmental friendliness.

Description

technical field [0001] The present invention relates to gas sensors, and in particular to a gas sensor having a non-stoichiometric LaFe x o 3 The invention relates to a method for preparing an ethanol gas sensor element with ultrafast response and recovery characteristics as a working substance. Background technique [0002] With the development of modern society, people pay more and more attention to health and safety issues. Ethanol is the main component of all kinds of alcohol, and it is also a flammable gas. Excessive drinking, drunk driving and leakage of ethanol have great health and safety Therefore, a highly sensitive, highly selective, stable and reliable ethanol gas sensor is of great significance to human health and life safety. Currently, doped semiconductor oxides SnO 2 , ZnO, TiO 2 , Fe 2 o 3 , V 2 o 5 etc. are widely used in the detection of ethanol gas. The principle is to use the oxygen adsorbed on the surface of the semiconductor oxide to react with...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N27/12B82Y30/00B82Y40/00
Inventor 曹恩思张雍家曹康孙礼郝文涛
Owner TAIYUAN UNIV OF TECH
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