In the 21 century,the fast development of industry in sources exploitation, petrochemistry,aviation and spaceflight,not only has promoted the advancement of the society,but also brought the hidden danger to the safety of human and the environment.With the increase of the people's environmental protection consciousness,the necessity and urgency of the detection of combustible and noxious gases has become the most important thing in recent years.Gas sensors based on metal oxide semiconductors have the ...