A non-oxygen adsorption mechanism for hydrogen detection of nanostructured SnO_2 based sensors

摘要

Several representative SnO2 nanostructures were synthesized hydrothermally, and their H-2 gas sensing performances in atmosphere were routinely investigated. We were surprised to find that the H-2 gas still induced a sensitive signal in vacuum where there was no or very few medium of adsorbed oxygen for charge transfer. In addition, the gas responses in vacuum were slightly higher than those in atmosphere. Given this, a non-oxygen adsorption model for gas sensing mechanism was proposed to account for this interesting phenomenon, in which H-2 gas could react with SnO2 surface directly in the absence of oxygen. The results showed that H-2 gas molecule was most likely to have a direct interaction with the O-2C atom on SnO2 (1 1 0) surface instead of the adsorbed O and transferred large electrons to SnO2, which would be crucial for future research on enhancing sensing properties of SnO2 based gas sensors.