Structure and chemistry of surface-doped Pt:SnO2 gas sensing materials

Abstract

Surface-doped Pt:SnO₂ was synthesized by impregnation of calcined SnO₂ made by an aqueous sol–gel route. The structure of the introduced Pt-dopant and its behaviour during gas exposure were examined by in situ and operando X-ray absorption spectroscopy. The results reveal that Pt forms a nano-sized PtO₂ phase, which was not found for bulk and surface doped materials, studied previously. In a comparative investigation of undoped and Pt-doped SnO₂ gas sensors the performance and the surface chemistry were investigated, the latter one using operando FT-IR spectroscopy. The results prove the strong influence of the different Pt structures on the surface chemistry of SnO₂, providing the basis for an understanding on the varying sensor performance of differently synthesized Pt:SnO₂ gas sensing materials.