Carbon nanotubes -based electrochemical properties

CNTs have been one of the most actively studied electrode materials in the past few years due to their unique electronic and mechanical properties. From a chemistry point of view, CNTs are expected to exhibit inherent electrochemical properties similar to other carbon electrodes widely used in various electrochemical applications. Unlike other carbon-based nanomaterials such as C60 and C70 [31], CNTs show very different electrochemical properties. The subtle electronic properties suggest that carbon nanotubes will have the ability to mediate electron transfer reactions with electroactive species in solution when used as the electrode material. Up to now, carbon nanotube-based electrodes have been widely used in electrochemical sensing [32-35], CNT-modified electrodes show many advantages which are described in the following paragraphs. 

Gabay T, Ben-David M, Kalifa I (2007) Electrochemical and biological properties of carbon nanotube based multi-electrode arrays. Nanotechnology, vol. 18 035201. 

Electronically conducting polymers (ECPs) such as polyaniline (PANI), polypyrrole (PPy) and po 1 y(3.4-cthy 1 cncdi oxyth iophcnc) (PEDOT) have been applied in supercapacitors, due to their excellent electrochemical properties and lower cost than other ECPs. We demonstrated that multi-walled carbon nanotubes (CNTs) prepared by catalytic decomposition of acetylene in a solid solution are very effective conductivity additives in composite materials based on ECPs. In this paper, we show that a successful application of ECPs in supercapacitor technologies could be possible only in an asymmetric configuration, i.e. with electrodes of different nature. 

Without doubt, the advent of carbon nanotubes has opened up iimovative perspectives for research and development of carbon electrodes. In this chapter, we have attempted to highlight the electrochemical properties of carbon nanotubes by rooting them mainly on their structural, electronic and chemical properties. If chirality of SWNTs could be controlled, it would be possible to probe electrochemically the unique electronic properties of the tubes with their corresponding unique DOS distribution and establish direct correlations between electronic structure and electrochemistry. However, so far, most of their electrochemical applications are based on ensembles of CNTs (MWNTs or SWNTs) in thin films supported on conductive surfaces or composites. Such ensembles, not so well defined from the structural point of view, contain a mixture of tubes with different diameters and DOS... 

Carbon nanotubes, especially SWNTs, with their fascinating electrical properties, dimensional proximity to biomacromolecules (e.g., DNA of 1 nm in size), and high sensitivity to surrounding environments, are ideal components in biosensors not only as electrodes for signal transmission but also as detectors for sensing biomolecules and biospecies. In terms of configuration and detection mechanism, biosensors based on carbon nanotubes may be divided into two categories electrochemical sensors and field effect transistor (FET) sensors. Since a number of recent reviews on the former have been published,6,62,63 our focus here is mostly on FET sensors. 

Another recent topic in detection of OP compounds based on ChE-modified biosensors is to use carbon nanotubes (CNTs) as an electrode modifier. CNTs are known to exhibit excellent electrochemical properties originating from high catalytic activity of edge-plane-like graphite sites at CNT ends and a large effective surface area. Lin et al. (2004) have reported that stable CNT-modified glassy carbon (GC) electrodes can be prepared by coating the surface of GC electrode with a suspension of CNT and can be used for sensitive determination of thiocholine (Liu etal,... 

Jagannathan, S. et al.. Structure and electrochemical properties of activated polyacrylonitrile based carbon fibers containing carbon nanotubes. J. Power Sources. 2008, iS5(2 , 676-684. 

Besides metal NPs, carbon micro and nanoparticles as well as carbon nanotubes are usually used as fillers in composites for electrochemical transducers. The following section focuses on the properties and main issues of carbon-polymer conducting composites based on nonconducting binders and polymers. 

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