SnO

2

nanopowders are synthesized by the sol-gel method and sintered in three atmospheres of air

vacuum and oxygen-rich

respectively

to prepare three different SnO

2

gas sensors.The crystalline phase

micromorphology and composition are characterized by X-ray diffractometer(XRD)

scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS).The gas-sensing characteristics of the three sensors to ethanol gas are tested simultaneously.The results show that for the sensor sintered under vacuum at 200℃

the gas response of SnO

2

sensor to ethanol gas at the optimal operating temperature can reach 26.01

with the response-recovery time shortened to 20s

and it presents good selectivity to ethanol gas.This is because vacuum annealing reduces the grain size of the powder

significantly increases the number of oxygen vacancies on the surface of the material

and further increases the proportion of adsorbed oxygen on the surface

which improves the gas-sensing performance of SnO

2

nanomaterials.This study can provide a reference for the preparation and application of low-cost

simple-process and high-performance resistive gas sensors.