Surface state effect on gas sensitivity in nano-hierarchical tin oxide. Issue 17 (1st December 2020) - Wang, Bing-Rong
Abstract: In this work, the mechanism of the effect of the surface state of tin oxide on its reductive gas sensitivity was investigated. A simple strategy was used to synthesize tin oxide samples with various structures. The strategy involved a hydrothermal reaction and calcination to transform the triclinic Sn3 O4 structure to the tetragonal SnO2 structure. A combination of experimental and theoretical results, was used to investigate the reasons for the good reductive gas sensitivity of SnO2 compared with those of other tin oxides. The results show that the origin of the gas sensitivity is surface bonding states that arise because of unoccupied electron orbitals. In contrast, for Sn3 O4, there are surface antibonding states of the terminal Sn atoms with lone pairs and gas adsorption is difficult. The effect of the surface state on the gas sensitivity is also related to the electronegativity of the atoms on the adsorptive surface, and the electronic interactions between a gas molecule and the adsorptive surface. The results provide a feasible strategy for enhancing the gas sensitivity of metallic oxides by modulation of the surface states of the metal oxide.