Gas sensing mechanism and properties of Ce-doped SnO2 sensors for volatile organic compounds

Doping often plays a critical role in governing gas sensing properties of nanomaterials. Different levels of cerium (Ce) doped-tin oxide (SnO2) nanomaterials are synthesized by a hydrothermal method in order to improve its sensor performance. X-ray diffraction and field emission scanning electronic microscopy are employed to examine the chemical composition and microstructures. It is found that Ce4+ doping can suppress the growth of large SnO2 crystallites and assist a uniform growth of large agglomeration spheres. The gas sensing properties is also investigated. By considering a variety of volatile organic compound gas and gas concentration, 2% Ce-doped SnO2 is found to exhibit the best gas sensing properties with excellent response and fast response-recovery even at low gas concentration of 10 ppm. Further comparative studies attribute this to enhanced capability of adsorbing oxygen on the surface. It is proposed that the main oxygen species on the surface of SnO2 is O2−, but O− may play a more important role in improving gas response.