Preparation of Carbon Nanotube Based Device and its Electrochemistry

The purpose of this research is to develop methodologies for the exploitation of carbon nanotube thin films as chemical and electrochemical sensors. In this study we prepared thin films of carbon nanotubes (CNT) by solution casting methods and then used a novel hybrid electrochemical-conductometric method to measure the CNT film electrical conductivity as a function of electrochemical bias and stimulus. The bias between the CNT film and the contacting electrolyte and the bias between the opposite ends of the CNT film (referred to as K1 and K2) were simultaneously controlled - analogous to a transistor with an electrolyte gate. A promising motif for sensing involved a cyclic voltammetric scan of K1 and K2 but with a 10 mVPP, 1 kHz AC signal summed onto the K2 potential, and thus generating a trans-film potential that was exploited, using a lock-in-amplifier detector, to monitor the CNT film conductance during the CV scan. In order to explore the chemical sensitivity of the CNT films in this setting, we examined blank electrolyte, dissolved ferrocene, and ultra-thin films of novel pyrene-modified iron(II)-terpyridine complex (Fe-tp-py) that binds to the CNT surface. Our principal finding is that this measurement method appears to discriminate between the CNT film trans-conductance and the interfacial electrochemical impedance because the iron(II)-iron(III) transition of the Fe-tp-py induced a clear change in the putative CNT film conductance that is distinct from blank or ferrocene control