Solubility and Electrical Response of Single Walled Carbon Nanotubes with Thiolate Mediated Gold Nanoparticle Attachment
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Solubility and Electrical Response of Single Walled Carbon Nanotubes with Thiolate Mediated Gold Nanoparticle Attachment Jingbiao Cui, Charles P. Daghlian1, Ursula J. Gibson Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, U.S.A. 1 Rippel Electron Microscope Facility, Dartmouth College, Hanover NH 03755, U.S.A. ABSTRACT Dodecanethiol-stabilized-Au nanoparticles are successfully attached to the sidewall of asgrown single walled carbon nanotubes (SWCNTs) via a simple approach. This provides a straightforward method to functionalize and dissolve SWCNTs of full length in organic solvents. The modified nanotubes exhibit dramatic increase in tube resistance and strong gate dependence with a memory effect, which is explained in terms of nanotube structure deformation induced by surface thiolation. The mechanism for Au particle attachment is shown to be via dodecanethiol groups.
INTRODUCTION Single walled carbon nanotubes have potential applications in nanoelectronics, chemical sensors, and highly efficient catalysts due to their unique structure and electronic properties [1]. A number of prototype nanodevices based on SWCNTs such as FETs (field effect transistors), RTSETs (room temperature single electron transistors), converters, logic gates, and memory devices have been demonstrated in the laboratory [2-7]. The insolubility of as-grown SWCNTs in common solvents, however, makes it hard to manipulate and process these materials. In recent years, considerable effort has been devoted to modification of SWCNTs with organic and inorganic functional groups to make them soluble in either aqueous solutions or organic solvents [8-11]. These modification processes also introduce new functionalities in the nanotubes, which greatly extend their potential applications. Pre-introduced defects or hydroxyl and carboxyl groups, which are normally created by aggressive or complicated acidic treatment at elevated temperature, are often required in order to make the modification succeed. The strong acidic treatments also considerably shorten the nanotubes. In the paper, we report on a simple route to modify the as-grown SWCNTs with thiolated Au nanoparticles using sonication. The modified nanotubes show complete solubility in organic solvents and the suspensions are stable for at least several months. The Au nanoparticles were found to attach to the tube wall as observed by a high resolution scanning electron microscope. Electrical transport properties are significantly changed after the modification. Metallic nanotubes show large increases in resistance and exhibit a gate dependence with memory effects. These effects are explained in terms of structural changes in the tube wall due to thiolation.
EXPERIMENTAL DETAILS Single walled carbon nanotube raw materials were purchased from Carbolex Inc., Lexington and used as received. No treatment or purification was performed before modification.
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The solvents used to dissolve SWCNTs are mixtures of toluene with dodecanethiol stabilized Au nanoparticles (
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