SnO₂ Nanosheets for Selective Alkene Gas Sensing

SnO2 nanosheets with the (101) crystal face mainly exposed were prepared to investigate their sensing properties. The SnO2 nanosheets were ∼150 nm in size and well-dispersed on the sensor chip. The gas sensing properties of the SnO2 nanosheets were investigated for CH4, C2H4, C2H6, C3H6, C3H8, 1-C4H8, cis-2-C4H8, trans-2-C4H8, iso-C4H8, and n-C4H10 gases. Additionally, the relationship between the sensor signal response of the SnO2 nanosheets and the orbital energy of the target gas molecules was investigated. It was found that the sensor exhibited remarkable selectivity to alkene gases which have high HOMO energies. The presence of partially unoccupied oxygen sites was confirmed from crystal structure analysis. In addition, defects on the surface of the SnO2 nanosheets were certainly identified from the surface analysis. On the basis of these results, it was determined that the gas selectivity for alkene gases of the SnO2 gas sensor was improved by the formation of oxygen vacancy defects. This effect is attributed to the superior oxygen desorption ability of the (101) crystal face of the SnO2 nanosheet.