Optical fiber sensor coated with copper and iron oxide nanoparticles for hydrogen sulfide sensing

摘要

This work presents the manufacture of optical sensors based on plastic optical fiber (POF) in U-shape and metallic nanoparticles for hydrogen sulfide (H2S) sensing. The manufacture of the sensors was divided into two stages, in the first stage the synthesis of oxidized metallic nanoparticles (copper oxide (CuONp) and iron oxide (FeONp)) were carried out with the Pulsed Laser Ablation in liquid. The nanoparticles were characterized to determine their optical properties, stability, morphology, structure, and size. The second stage consisted of the sensors' development and their application in H2S sensing. Two sets of U-shaped POF sensors where manufactured, one with sensors covered with CuONp, and the other with sensors covered with FeONp. The results showed that all sensors were capable of detecting a gaseous mixture containing 200 ppm of H2S, and that the sensors coated with CuONp showed a higher sensitivity than the FeONp-covered sensors. However, the sensors manufactured with CuONp showed a non-reversible chemisorption behavior, while the sensors manufactured with FeONp exhibited reversible physisorption behavior. Comparatively, one of the sensors covered with FeONp was found to have a sensitivity seven times higher than the less sensitive sensor. In addition, that most sensitive sensor also showed a quick recovery time of less than 5 min and a rise time of around 6 min. Finally, the sensor was exposed to other reducing gases such as NH3 and CH4 and the results indicated that the developed sensor demonstrate selectivity to H2S. All sensors were tested at room temperature (25 degrees C).