A WS2/CNF Nanocomposite for Electrochemical Sensing Applications
Authors: Barwa Tara N , Alves Daniele , Luo Yiran , Dempsey Eithne , Breslin Carmel B 
Published: August 2024

Successful environmental monitoring is crucial to safeguarding humans and the natural world. The presence of antibiotics in aquatic environments has become a pressing global concern, posing potential risks to both ecosystems and public health. Extensive use of antibiotics in medical treatment and agriculture has led to their release into water bodies through various pathways, contributing to water contamination. Detecting and monitoring antibiotic residues in water is crucial to understanding the extent of contamination and mitigating its adverse effects. Furthermore, the escalating concern over pharmaceutical contaminants in the environment has prompted significant research efforts towards the development of advanced sensing technologies.

Recently, 2D materials have emerged as promising candidates for environmental sensing, due to their unique properties and potential applications. Transition-metal dichalcogenides or TMDs, are two-dimensional (2D) materials comprising of MX2, with M a transition metal atom e.g. Mo, W etc. and X, a chalcogen atom S, Se or Te1. The M atoms are sandwiched between two layers of X atoms with robust in-plane covalent bonds, and weak van der Waals forces between the planes. Among the TMDs, tungsten disulfide (WS2) exhibits outstanding properties, such as high electronic conductivity, large capacitance, high surface area, and chemical stability. This study explores the promising characteristics of WS2 and its synergistic potential of combining it with carbon materials to develop hybrid structures2. Carbon nanofibers (CNFs) exhibit exceptional properties that make them promising candidates for sensor applications. With their large surface area, and excellent electrical conductivity, CNFs offer a unique platform for the development of sensitive and selective sensors. In addition, CNFs versatility allows for functionalization, enhancing their chemical properties and facilitating tailored interactions with target analytes. Furthermore, owing to these notable properties, carbon nanofibers complement WS2 in the development of innovative sensor structures. Here, WS2 was combined with functionalized carbon nanofibers, to create a composite structure that was employed to detect ornidazole (ORZ), an antibiotic drug.

Ornidazole, belonging to the nitroimidazole class of antibiotics, is commonly employed in the treatment of various genitourinary tract and protozoal infections3. Beyond the immediate therapeutic benefits, antibiotics such as ornidazole can persist in the environment, posing long-term risks. Moreover, excess ORZ in the environment has potential mutagenic & carcinogenic effects, and can lead to the development of antibiotic resistant pathogens. In this study, the WS2 /CNF nanocomposite was synthesized using hydrothermal synthesis and subsequently dispersed in ethanol and water, and then drop casted on a glassy carbon electrode. Prior to synthesis, the CNFs were functionalized using a low cost, environmental friendly method, thus enhancing their chemical properties. Herein, the resulting WS2/CNF composite demonstrates its efficacy in detecting ornidazole (ORZ), and shows excellent potential for the development of electrochemical sensors. Overall, the work here aims to underscore the continuous development of electrochemical sensor technology, emphasizing its pivotal role in addressing the growing challenges associated with drug contamination in the environment.

(1) Manzeli, S.; Ovchinnikov, D.; Pasquier, D.; Yazyev, O. V.; Kis, A. 2D Transition Metal Dichalcogenides. Nature Reviews Materials. 2017. https://doi.org/10.1038/natrevmats.2017.33.

(2) Santos, B. G.; Gonçalves, J. M.; Rocha, D. P.; Higino, G. S.; Yadav, T. P.; Pedrotti, J. J.; Ajayan, P. M.; Angnes, L. Electrochemical Sensor for Isoniazid Detection by Using a WS2/CNTs Nanocomposite. Sensors and Actuators Reports
2022, 4. https://doi.org/10.1016/j.snr.2021.100073.

(3) Koventhan, C.; Vinothkumar, V.; Chen, S. M. Development of an Electrochemical Sensor Based on a Cobalt Oxide/Tin Oxide Composite for Determination of Antibiotic Drug Ornidazole. New Journal of Chemistry
2021, 45 (28). https://doi.org/10.1039/d1nj01345a