Hydrothermal Synthesis Of Tin Oxides And The Enhancement Of Their Gas Sensing Properties

Semiconductor metal oxides have attracted a great deal of attention over the past decades largely because it’s widely used as gas sensing materials,solarcells,catalysts,transparent electrodes,photo electronic devices and spintronic.Moreover,they are also of great significance in fundamental science.In particular,as great sensing materials,they exhibit fine and stable recovery.In the meantime,they can be fabricated via simple process.Despite of theses merits,metal oxides based gas sensors still suffer issues,restraining their application as gas sensing materials.Many efforts have been made to tackle these gaps.In this paper,size-controllable method and metallic doping have been taken to improve gas sensing properties accordingly for SnO₂ nanomaterials under hydrothermal conditions.The relevant morphologies and crystal structures of the obtained samples were investigated by X-Ray diffraction（XRD）,field emission scanning electron microscopy（FESEM）,and high resolution transmission electron microscopy（HRTEM）,respectively.Meanwhile,their gas sensing properties were also tested.Firstly,SnO₂ hierarchical microstructures assembled by either nanoneedles or nanosheets were designed and synthesized through hydrothermal method successfully.It’s found that the existence of PVP can tailor the morphologies,and the sizes of the blocking units can be controlled by tuning temperature.Moreover,nanoneedles assembled SnO₂ had higher gas response while nanosheets assembled SnO₂ hierarchical microstructures had quicker response and recovery,and thinner ones generally performed better gas sensing performance.Upon that our work systematically synthesized size-controllable SnO₂ and investigated the relationship between the morphologies and gas sensing properties,which provided abundant inspiration to the development of gas sensing materials.Secondly,pristine and Cu-doped SnO₂ spheres were synthesized using facile hydrothermal method,their microstructures and gas sensing performance were also investigated.It’s demonstrated that Cu doping can significantly enhance the gas sensing properties of SnO₂ towards H₂S compared to pristine SnO₂,Cu-doped SnO₂ showed higher gas response and quick response and recovery.First principles calculations revealed that adsorption energy of H₂S on Cu-doped surface was lower than that on undoped one.And the interaction between adsorbed H₂S and Cu-doped surface was stronger than that between adsorbed H₂S and pristine SnO₂ surface,which consequently improved gas sensing performances of SnO₂ toward H₂S.