CNT-coated electrodes

CNT-coated electrodes can be constructed easily as long as stable CNT suspensions are obtained. However, one needs to choose a suitable surfactant dispersant for the fabrication of CNT/surfactant-modihed electrodes with high catalytic and good selectivity toward the analytes. 

It has been demonstrated that the presence of CNTs greatly increases the oxidation peak current of 6-benzylaminopurine. The CNT-modified electrode is suitable for the determination of trace amounts of benzylaminopurine and has the advantages of high sensitivity, quick response, and good stability [86], Wang et al. have studied the electro-catalytic oxidation of thymine at a a-cyclodextrin incorporated CNT coated electrode in an alkaline media. A sensitive detection scheme for thymine has been further developed by using differential pulse voltammetry [87], The electrochemical determination... 

In recent years, there are more applications based on the layer-by-layer fabrication techniques for CNT-modified electrodes. This technique clearly provides thinner and more isolated CNTs compared with other methods such as CNT-composite and CNT coated electrodes in which CNTs are in the form of big bundles. This method should help biomolecules such as enzymes and DNA to interact more effectively with CNTs than other methods, and sensors based on this technique are expected to be more sensitive. Important biosensors such as glucose sensors have been developed using this technique, and further development of other sensors based on the layer-by-layer technique is expected. 

The oxidative procednre of CNTs alone may generate a stable CNT suspension which can be used for the preparation of CNT coated electrodes. Other procedures to prepare CNT suspensions are based on non-covalent stabilization of CNTs by using either surfactants or polymers. An excellent review on this subject has been published... 

A major breakthrough was reported in our laboratory in 2009 regarding novel Ni-based CNT-coated electrodes with remarkable electrocatalytic activities for both H2 evolution and uptake [51]. The molecular Ni complex used in this study was efficiently covalently attached to MWCNTs using the diazonium strategy, thanks to a fruitful collaboration with Bruno Jousselme and Serge Palacin in CEA Saclay (France). 

Several sensor configurations are manufactured from randomly oriented CNTs, conductive CNT films, and CNT-coated electrode surfaces to transistor-based sensors. CNT films and composites are well suited for macro- and microscale sensing platforms, such as smart wearable fabrics and lab-on-chip devices, in which concentrations of analytes are above several micromolars. Smaller electrodes, with tips ranging from hundreds of nanometers to hundreds of micrometers, have been coated with CNTs to enhance their sensitivity. 

---