A hybrid gas-sensing material based on porous carbon fibers and a TiO₂ photocatalyst

The electrode material for a gas sensor was prepared from electrospun carbon fibers. The electrode material was chemically activated to enlarge the gas adsorption sites, and carbon nanotubes (CNTs) were embedded into the polyacrylonitrile-based carbon fibers to enhance their electrical conductivity. TiO₂ was used as an additive to promote NO gas degradation and to improve their response in NO gas sensing. The chemical activation process increased the specific surface area and pore volume of the carbon fibers to values in excess of 2000 m²/g and 1.0 ml/g, respectively. To investigate the photocatalytic effects of the TiO₂ additive, NO gas sensing was conducted in the presence and absence of ultraviolet irradiation. The subsequent results indicate that the response of the sensor was improved due to the TiO₂-photocatalyzed decomposition of NO gas and the subsequent adsorption of HNO₂, NO₂, and HNO₃. The electrical resistance of the sensor was significantly reduced during NO gas sensing due to the electron hopping effect, and highly efficient gas adsorption was observed. In conclusion, a sensitive gas sensor electrode was realized by fabricating a porous material to increase the efficiency of gas adsorption, adding CNTs to improve its electrical conductivity and adding TiO₂ photocatalysts to promote NO decomposition.