Improved gas sensing of electrospun carbon fibers based on pore structure, conductivity and surface modification

A polyacrylonitrile and carbon black complex was fabricated as a gas sensor using an electrospinning method. The electrospun fibers were thermally treated to obtain carbon fibers, which were then chemically activated to improve the active sites for gas adsorption. The surface of the activated sample was modified by a fluorination treatment. The electrical conductivity was improved by the inclusion of carbon black additives. The activation process improved the porous structure, increasing the specific surface area around 100 times. The gas sensing ability was improved by the developed porous structure and induced functional groups. This treatment improves each of the three steps in the gas sensing mechanism. First, the induced functional groups attracted the target gas to the surface of the gas sensor through induced functional groups. Second, the pore structure significantly increased the amount of adsorbed gas. Third, the electrically conductive carbon black additives resulted in an efficient transfer of the resistive response from the surface of the gas sensor to the electrode. In total, the sensor sensitivity for NO and CO gases was improved about five times based on the effects of chemical activation, carbon black additives, and fluorination treatments.