Improvement And Mechanism Of Gas Sensing Properties Of Hollow Multi-Shell SnO₂

Gas sensors,the gas information sensing layer in the Internet of Things system,play a significant role in air quality monitoring,air pollution prevention and control,clinical diagnostics,and other aspects with the system’s rapid development.However,the slow response time and poor repeatability of oxide-semiconductor sensors are still the main problem at present.This paper combines the current research status and development forms of semiconductor gas sensors.The gas-sensitive performance of SnO₂ sensor was improved by changing morphology and doping with precious metals.The specific research content is as follows:Carbon microsphere templates with uniform size were prepared by hydrothermal method.The prepared templates were immersed in precursor solutions of different concentrations and then three kinds of materials were prepared by temperature-programmed annealing.TEM analysis showed that single-shell SnO₂,double-shell SnO₂ and triple-shell SnO₂ had obvious structure and the number of shells with clear shell resolution.SnO₂ sensitive materials based on the number of double-shell SnO₂ showed a good response to ethanol,and the detection limit of ethanol could reach 1 ppm,showing excellent repeatability.At the same time,the response time of 100 ppm ethanol was tested,in which the response time of the bivalve material was 2 s.The precious metal Au was wrapped in the inner core of the carbon ball template by the similar preparation method in the previous chapter,and then the SnO₂ material containing gold core was obtained by annealing through the same follow-up steps.The SnO₂ material was modified by using the overflow effect and catalytic properties of Au.The agglomerated gold nanoclusters and the gold peaks in XPS were obviously observed by TEM.The results show that the bivalve structure containing gold is sensitive to 100 ppm ethanol up to 29,The SnO₂ material has a very fast response time of 1 s and long-term stability of 21 days.According to the experimental conclusions of the first two chapters.Deep analysis of the structural characterization of the two materials showed that the shrinkage of lattice spacing in the materials during the synthesis of SnO₂ was influenced by manufacturing defects（Au）.Introduce"static"lattice strain.The results show that the influence of the dislocation on the lattice strain is great.Therefore,we propose a promising design and method for high-performance sensors.The effect of SnO₂ nanocrystalline on ethanol properties was induced by strain control of the electronic conductivity of the material in ethanol and adjustment of the carrier concentration in Au doped SnO₂ nanocrystalline atmosphere.