Tuning the functional interface of carbon nanotubes by electrochemistry: Toward nanoscale chemical sensors and biosensor
- PDF / 580,091 Bytes
- 12 Pages / 584.957 x 782.986 pts Page_size
- 74 Downloads / 163 Views
The ability to tune the functional interface of single-walled carbon nanotubes in a versatile manner is key to the success of deploying them as an active material in chemical and biological sensors. Here we present an overview of our device strategies demonstrating the use of controlled electrochemical functionalization to tune this interface by bringing in different functionalities ranging from metallic nanoparticles to biomolecules onto the nanotube surface. The extent of such a functionalization is tunable, providing us with a good control over sensitivity, selectivity, and detection limit of the realized sensors. Moreover, the sensor mechanisms have been analyzed. Taken together the methods and results outlined here constitute a general framework for the rational design of nanoscale field-effect-based chemical sensors and biosensors.
I. INTRODUCTION
Carbon nanotubes (CNTs) are an interesting class of materials due to their quasi-one-dimensional structure coupled to novel electronic and mechanical properties.1 They have been proposed as an active material for a number of applications.1,2 In spite of this promise, there are very few applications which have been realized commercially.3 An important step toward this direction is the ability to tune the physical and chemical properties of the nanotube material in a versatile manner. Depending on the application in mind, the functionality presented by the interface between the CNT and its environment needs to be modified in a controlled manner. For example, to realize chemical sensors, it is vital to have the capability to modify the nanotube surface with a range of functional groups that are specific to the analyte to be detected.4,5 The chemistry of CNTs plays a key role in rendering the nanotube surface with such functionalities.6–8 The chemical reactivity of CNTs due to their increased curvature is higher than their layered counterparts such as graphite or graphene.9 Through a range of chemical functionalization routes, the interface of the CNTs can be prepared appropriately for the application in question.10,11 The methods used for functionalizing CNTs can be classified into thermally activated chemistry, photochemistry, and electrochemistry.9 Thermally activated chemistry includes oxidation and addition reactions that are used
a)
Address all correspondence to this author. e-mail: [email protected] This paper has been selected as an Invited Feature Paper. DOI: 10.1557/jmr.2011.410 J. Mater. Res., Vol. 27, No. 2, Jan 28, 2012
to attach functional groups covalently to the sidewalls of the CNTs.6 The ends of the nanotubes are in general more reactive.12 However, for most applications it is necessary to functionalize the sidewalls to obtain a sufficient density of functional groups on the CNT surface. Non-covalent functionalization is mainly achieved by utilizing p–p or hydrophobic interactions of the functional moieties with the CNT surface.13 Photochemistry involves the activation of precursor molecules by light, resulting in the sidewall covalent addition of th
Data Loading...
