Method for preparing high-sensitivity low working temperature ethanol gas sensor element

Abstract

The invention discloses a method for preparing a high-sensitivity low working temperature ethanol gas sensor element. LaFeO3 nanoparticles prepared through an improved sol gel method are selected as a working substance to prepare an indirectly heated ceramic tube gas sensor element. Through the adding of ethylene glycol (EG) in a precursor, the distribution uniformity of positive ions in a solution and the hole carrier concentration in particles are increased, neither heavy metal nor rare earth precious metal is added, and element resistance is reduced. Through introduction of a secondary sintering process, particle sizes and agglomeration phenomena are reduced, the content of particle surface Fe4+ions and oxygen absorption capability are improved, and thus ethanol sensitivity is improved and the working temperature is lowered. The LaFeO3 indirectly heated gas sensor element prepared through the method can have sensitivity of 46 for 200 ppm of ethanol under a working temperature of 112 DEG C, is high in sensitivity to the ethanol and low in working temperature and has the advantages of being low in cost and environmentally friendly.

Description

technical field [0001] The present invention relates to gas sensors, in particular to LaFeO prepared by an improved sol-gel method 3 The invention relates to a method for preparing an ethanol gas sensor element with high sensitivity and low working temperature 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 the detected...

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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

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