Electrochemical Sensing Properties of Ultra Long Aligned Multi-Walled Carbon Nanotube Microelectrodes
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0963-Q21-05
Electrochemical Sensing Properties of Ultra Long Aligned Multi-Walled Carbon Nanotube Microelectrodes Niramol Punbusayakul1,2, Lijie Ci2, Saikat Talapatra2, Werasak Surareungchai1, and Pulickel M. Ajayan2 1 School of Bioresources and Technology, King Mongkut¡¯ s University of Technology Thonburi, 83 Moo 8, Bangkhuntien-Chaitalay Rd, Thakam, Bangkok, 10150, Thailand 2 Material Science and Engineering, Rensselaer Polytechnic Institute, 110 8th St., Troy, NY, 12180
ABSTRACT We report on the electrochemical properties of ultra long aligned multiwalled carbon nanotube (MWNT) bundles synthesized using water-assisted chemical vapor deposition process. Cyclic voltammogram with diffusion-controlled-reversible reaction obtained at MWNT electrodes in 10 mM K3(Fe(CN)6) /0.1 M KCl solution with varying scan rates indicates that radial diffusion mass transport is dominant at these electrodes. We further show that these electrodes can detect very low concentrations of ascorbic acid (AA) and dopamine (DA) (0.7 µM for AA and 1.87 µM for DA ). The excellent electrochemical properties along with nice performance for single species detection suggest that these MWNTs are promising electrode materials for developing high sensitive chemical and/or biological sensors. INTRODUCTION The need for better electrochemical devices has lead to the search for new and faster electrochemical sensing materials. [1-2] Since their discovery, Carbon Nanotubes (CNTs) are envisioned as novel materials for various applications ranging from gas storage to components for nanoelectronic devices. [1-3] Due to their excellent properties such as large specific surface area, high thermal, mechanical and electrochemical stability, superior ability to accumulate analyte and minimum surface fouling effects, [1-3] CNTs hold promise for potential materials for diverse electrochemical applications such as electrochemical sensing. The major demerit of planar electrode in electrochemical sensing is the Ohmic drop, which creates a large double layer capacitance resulting in a distorted voltammogram. The reduction of the electrode to micron size can overcome this demerit and further enhances the electron transfer and mass transport at the working electrode. These provide microelectrode with high sensitivity and reduce signal-to-noise ratio. However microelectrode fabrication involves complication and requires expertise and this holds true even for CNT electrodes. Previously various CNT configurations were used as electrodes in electroanalysis. [4-6] However, one of the most encountered causes for limitation of CNTs applications in electrochemistry other than their hydrophobicity is their short length. Consequently, a great deal of interest in creating long CNT materials for electrochemical applications is under intense investigation. For example, electrodes made from spun fibers of purified CNTs show very good performance for electroanalysis. [7] Similarly, directly synthesizing long CNTs will expand their applications in various fields in nanotechnology as we
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