New Generation of Electrochemical Sensors Based on Multi-Walled Carbon Nanotubes

Multi-walled carbon nanotubes (MWCNT) have provided unprecedented advances in the design of electrochemical sensors. They are composed by sp2 carbon units oriented as multiple concentric tubes of rolled-up graphene, and present remarkable active surface area, chemical inertness, high strength, and low charge-transfer resistance in both aqueous and non-aqueous solutions. MWCNT are very versatile and have been boosting the development of a new generation of electrochemical sensors with application in medicine, pharmacology, food industry, forensic chemistry, and environmental fields. This work highlights the most important synthesis methods and relevant electrochemical properties of MWCNT for the construction of electrochemical sensors, and the numerous configurations and successful applications of these devices. Thousands of studies have been attesting to the exceptional electroanalytical performance of these devices, but there are still questions in MWCNT electrochemistry that deserve more investigation, aiming to provide new outlooks and advances in this field. Additionally, MWCNT-based sensors should be further explored for real industrial applications including for on-line quality control.Simone Morais is grateful for financial support from the European Union (FEDER funds through COMPETE) and National Funds (Fundação para a Ciência e Tecnologia-FCT) through projects UID/QUI/50006/2013 and AAC No. 02/SAICT/2017—project No. 029547 “CECs(Bio)Sensing—(Bio)sensors for assessment of contaminants of emerging concern in fishery commodities”, by FCT/MEC with national funds and co-funded by FEDER. She also thanks financial support by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF): projects Norte-01-0145-FEDER-000011 and Norte-01-0145-FEDER-000024. Acknowledgments: T.M.B.F. Oliveira thanks the Brazilian agencies CNPq, CAPES and FUNCAP for all scientific support to his projects with nanostructured materials.