(Invited) Carbon Nanotubes from Synthesis, Assembly to Electrochemical Sensors

Abstract

The unique physical properties of individual Carbon Nanotubes (CNTs) surpass the properties of many advanced materials available today. Due to their large surface area, chemical stability, and electrical conductivity, they are the most promising candidates for a large number of electroanalytical applications. A material for these applications requires high purity CNT assemblies like fibers and films, that have good electrical conductivity, in some case additional insulation coatings. This talk will report the synthesis of catalyst free CNTs, their assembly into ribbons at 15.9 m/s speed, fiber processing and polymer coating into a micro-cable format. CNT micro-cable was used for detection of toxic metals contaminants in H2O, that are considered as the most significant potential threats to human health by ATSDR and EPA. Polystyrene coated CNT fiber was used as the working electrode; bare CNT thread was used as the auxiliary electrode; and a pseudo-reference electrode was fabricated by electroplating CNT fiber with Ag that is subsequently anodized in chloride solution to form a layer of AgCl. The Ag/AgCl coated CNT fiber electrode provides stable potential comparable to the conventional liquid-junction type Ag/AgCl reference electrode, while bare CNT fiber auxiliary electrode provided a stable current comparable to a Pt wire auxiliary electrode. This all-carbon CNT fiber three electrode cell is evaluated for simultaneous detection of trace levels of heavy metal ions by anodic stripping voltammetry (ASV). Hg2+, Cu2+ and Pb2+ in H2O were detected successfully, and the detection limits are 1.05 nM, 0.53 nM and 0.57 nM for Hg2+, Cu2+ and Pb2+, respectively. These electrodes significantly reduce the dimensions of the conventional three electrode electrochemical cell and have the potential to become low cost and disposable sensor.