High-sensitivity gas sensor using electrically conductive and porosity-developed carbon nanofiber

A polyacrylonitrile/carbon nanotube (CNT) complex was fabricated for use as a gas sensor using an electrospinning method. The surfaces of the multi-walled carbon nanotubes (MWCNTs) were modified by using a fluorination treatment to provide sufficient dispersion within the electrospun fibers. The electrospun fibers were thermally treated to obtain carbon fibers and then chemically activated to increase the number of active sites for efficient gas adsorption. The activation process improved the porous structure by increasing the specific surface area by approximately 115-fold. The gas-sensing ability and response time improved by introducing both the porous structure and the fluorinated MWCNTs. High-performance gas sensing followed a proposed mechanism, which included the effects of the activation and the MWCNT additive. The pore structure that developed as a result of activation significantly increased the amount of adsorbed gas and produced the high sensitivity of the gas sensor, while the MWCNTs led to a quick sensor response time due to the efficient transfer of resistance changes occurring on the surface of the fibers. Overall, due to the effects of chemical activation and fluorinated MWCNT additives, the sensor's sensitivity to NO gas improved by approximately 8 times, the response time decreased by approximately 60%. (C) 2011 Elsevier B.V. All rights reserved.