Fiber-Optic Plasmonic Sensor Utilizing CTAB-Functionalized ZnO Nanoparticle-Decorated Carbon Nanotubes on Silver Films for the Detection of Catechol in Wastewater

A silver thin-film-based fiber-optic plasmonic sensor for the detection of a phenolic analyte, catechol, is elicited in the present study. The sensor relies on the interaction of catechol with a cetyltrimethylammonium-bromide (CTAB)-functionalized zinc oxide/carbon nanotube (ZnO/CNT) nanocomposite coated over the silver film. A simple sol–gel method is reported for the synthesis of the nanocomposite. The morphological, elemental, and structural characterizations of the nanocomposite are confirmed by various microscopic and spectroscopic techniques. The sensor’s performance is studied for the catechol concentration range of 0–100 μM. The fabricated probe shows efficiency in a very wide pH range depending on the concentration of CTAB utilized in the preparation of the probe. Various operational parameters are adjusted to obtain the optimum sensor performance. Efficiently reproducible and selective performance is obtained after analyzing various possible interferants like dopamine, ascorbic acid, hydrazine, and so on. The approach is found to be feasible for real sample analysis with an efficient recovery percentage. The highest sensitivity of the sensor, 5.46 nm/μM, is obtained at the lowest catechol concentration with a limit of detection of 0.1 μM. The utilization of an optical fiber makes the approach very simple and miniaturized for on-field detection or real-time remote sensing applications. The surface plasmon resonance results of the sensor reveal the excellent performance of the CTAB-functionalized ZnO/CNT nanocomposite in the effective quantification of catechol.