At present, the industry is developing rapidly, which results in an increased emission of toxic gases. Therefore, it is of great importance to develop inexpensive and high-performance sensors for real-time monitoring and quantification of these toxic gases in all fields including environmental monitoring, medicine, industrial processing and agriculture. Different types of chemical sensors based on polymers, carbon nanotubes, graphene, zeolites and metal oxide nanomaterials can be used to detect the emission of various toxic gases. Among them, semiconductor gassensors based on metal oxide nanomaterials have attracted a great deal of attention due to their advantages such as excellent fabrication technology, low cost, long lifetime and wide range of target gases. Furthermore, a great interest in them is the integration with complementary metal-oxide semiconductors (CMOS) or microelectromechanical system (MEMS) processes.
Titanium dioxide is an n-type semiconductor with excellent electrical properties, thus finding its wide use in photocatalysis, solar cells and sensors. The surface-to-volume ratio is large for 1D metal oxide semiconductor nanostructures such as nanowires, nanorods, nanobelts and nanofibers. These 1D nanostructures like nanowires and nanorods are widely used for gas sensors. The intrinsic properties of these nanostructures increase the effective surface area of the material by facilitating the interaction with target gas molecules and the diffusion into the material. These nanomaterials are synthesized by hydrothermal method, sol-gel method and electrostatic spinning method to be fabricated by deposition on a substrate.
Some time ago, Pak Jong Sung, a section head at the Faculty of Chemical Engineering, prepared TiO2 nanopaper (long nanowire/nanofiber membranes) similar to the conventional paper in mechanical performance by combining high-temperature hydrothermal nanofiber synthesis and paper preparation, and then characterized its structural properties. This 2D nanomaterial is in disordered arrays of nanowires/nanofibers and of highly porous structure with flexible mechanical strength, and its thickness could be controlled arbitrarily. Thus, this material exhibits intrinsic properties of nanomaterials as sensing materials as well as high chemical, thermal and mechanical stability. However, this material has low selectivity for gas sensing due to the gas sensing properties of semiconductor materials.
To overcome this shortcoming, Ri Son Ho, a student at the same faculty, has prepared a novel gas sensing material with an excellent performance using V2O5-doped TiO2 nanopaper and characterized its SO2 sensing, under the guidance of Pak Jong Sung.
This sensing material exhibited high conversion efficiency of SO2 to SO3 and sensing properties due to its flexible mechanical strength, high porosity, chemical and thermal stability and high catalytic activity of V2O5.
For more information, please refer to his paper “Sulfur dioxide gas sensor based on vanadium oxide doped TiO2 nanopaper” in “Engineering Research Express” (SCI).
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