Electrospun Polyacrylonitrile Nanofibers Mixed with Citric Acid as a Quartz Crystal Microbalance Ammonia Vapor Sensor

Abstract

AbstractThe detection of ammonia vapor in the air is always challenging and in great demand, with the main issues are their low sensitivity. In this contribution, we developed a quartz crystal microbalance (QCM) gas sensor to detect ammonia vapor in the air using electrospun polyacrylonitrile (PAN) nanofiber mixed with citric acid (CA) as its sensing material. The nanostructured morphology of the as‐prepared nanofiber sensors was confirmed using scanning electron microscopy (SEM), while the existence of the CA in the PAN/CA nanofiber confirms using Fourier transform infrared (FTIR) spectroscopy. The average diameter of the PAN and PAN/CA nanofiber sample was found in the range of 260 nm to 307 nm. The highest sensor sensitivity was obtained by the PAN/CA4 nanofiber sensor with the value of 0.28 Hz/ppm, increasing almost 4 times compared to the unmodified PAN nanofiber sensor (0.075 Hz/ppm). Moreover, the sensor also shows good reversibility, fast response/recovery time, and excellent repeatability sensing performance. The addition of CA into the PAN nanofiber structures enhances the sensor sensitivity, probably due to the enrichment of carboxyl group at the sensor surface. This work could become a promising and alternative way to enhance the sensitivity of a QCM gas sensor modified with polymers doped with suitable compounds.