A non-oxygen adsorption mechanism for hydrogen detection of nanostructured SnO2 based sensors. (January 2019) - Zhu, Ling
Graphical abstract: We report a hydrothermal synthesis of SnO2 solid spheres, nanoneedle-assembled nanourchins and nanosheet-assembled nanoflowers. A non-oxygen adsorption model for gas sensing mechanism was proposed, which was understood via combing experimental observations and first principles calculations. Highlights: Different SnO2 nanostructure was successfully synthesized by hydrothermally. The H2 gas enabled react with the SnO2 surface directly A non oxygen adsorption model was proposed. Abstract: Several representative SnO2 nanostructures were synthesized hydrothermally, and their H2 gas sensing performances in atmosphere were routinely investigated. We were surprised to find that the H2 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 H2 gas could react with SnO2 surface directly in the absence of oxygen. The results showed that H2 gas molecule was most likely to have a direct interaction with the O2C 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.