Morphological features and electrical properties of hollow SnO2 for room temperature CO sensing

This work highlights the synthesis of hollow SnO2 nanostructures by hydrothermal method and investigation of their morphological features, crystal structure, surface area, elemental composition, and change in resistance to gas as the electrical properties. The synthesis of hollow SnO2 nanostructures was accomplished by using a modified hydrothermal method starting with a core@shell SiO2 template, and its nanostructure properties were compared with a SiO2@SnO2 and template-free SnO2. The STEM analysis revealed that the SnO2 nanomaterials had a spherical morphology. The crystallite diameters of the hollow and template-free SnO2 spheres were 3.3, and 4.6 nm, respectively, and their optical bandgap energies were determined to be 4.10, and 3.90 eV, respectively, indicating the influence of quantum confinement effects. The compositions of the SiO2@SnO2 and the hollow SnO2 nanomaterials were ascertained by XPS studies, which confirmed the purity of SnO2. By a simple sensing test, the hollow SnO2 structures were utilized in the sensing of CO at room temperature and the sensor response was found to be six times higher than that of the template-free SnO2 spheres due to their lower domain size and a large number of active sites. This study indicates that the hollow SnO2 obtained from a core@shell SiO2 template has the potential to become a viable sensor material for CO detection at room temperature.