Role of Sb and Co Doping in SnO₂ Sensing Properties toward Ethanol ^†

The adsorption and desorption of oxygen molecule on the surface of oxide semiconductors are the basis for sensing reactions between the surface oxygen species and the target gases molecules. Combined with experiments and theoretical calculations, we found that antimony impurities were conducive to the promotion of oxygen adsorption and dissociation on the surface of SnO₂. However, the narrow Debye length had an adverse effect on sensing properties of Sb doped SnO₂. On the contrary, the introduction of cobalt dopant will generate more oxygen vacancies and reduce the concentration of electrons and consequently the Debye length will become longer, which makes the transduction more significant. Namely, the same amount of charge transfer between surface and analyte gases can cause a larger change in resistance than pure metal oxide. The aforementioned inferences about doped metal oxides indicate that for optimizing their sensing properties, doped oxides with appropriate dopant and unique structure which can balance the recognition function and transduction function are required.