Carbon nanotube detectors for microchip CE: Comparative study of single‐wall and multiwall carbon nanotube, and graphite powder films on glassy carbon, gold, and platinum electrode surfaces

Abstract

The performance of microchip electrophoresis/electrochemistry system with carbon nanotube (CNT) film electrodes was studied. Electrocatalytic activities of different carbon materials (single-wall CNT (SWCNT), multiwall CNT (MWCNT), carbon powder) cast on different electrode substrates (glassy carbon (GC), gold, and platinum) were compared in a microfluidic setup and their performance as microchip electrochemical detectors was assessed. An MWCNT film on a GC electrode shows electrocatalytic effect toward oxidation of dopamine (E(1/2) shift of 0.09 V) and catechol (E(1/2) shift of 0.19 V) when compared to a bare GC electrode, while other CNT/carbon powder films on the GC electrode display negligible effects. Modification of a gold electrode by graphite powder results in a strong electrocatalytic effect toward oxidation of dopamine and catechol (E(1/2) shift of 0.14 and 0.11 V, respectively). A significant shift of the half-wave potentials to lower values also provide the MWCNT film (E(1/2) shift of 0.08 and 0.08 V for dopamine and catechol, respectively) and the SWCNT film (E(1/2) shift of 0.10 V for catechol) when compared to a bare gold electrode. A microfluidic device with a CNT film-modified detection electrode displays greatly improved separation resolution (R(s)) by a factor of two compared to a bare electrode, reflecting the electrocatalytic activity of CNT.

Biomimetic Sensors for Rapid Testing of Water Resources

“…In an effort to use an electrode material both more resistant to biofouling and possessing a larger potential range compared to noble metal electrodes [15][16][17], we developed a new method for the fabrication of carbon paste electrodes (CPEs) that optimizes their stability in a flow-based microfluidic device [18]. The greater stability of these CPEs results from exploiting beneficial properties of both soft and rigid composites, which are used as the binder, during CPE fabrication.…”

Nanomaterials as electrochemical detectors in microfluidics and CE: Fundamentals, designs, and applications

“…The underlying bulk electrode is modified with CNT film, usually by the deposition of a suspension of CNTs in solvent (e.g. DMF or aqueous solution of a polymer) and allowing the solvent to evaporate [16,34,35,39,[43][44][45][46][47]. The CNTs consequently create a random CNT films on the surface of the electrodes.…”

“…The effects of the performances of different kinds of CNT, such as MWCNT and single-walled carbon nanotube (SWCNT), were studied by several groups. Using wellestablished probes as catecholamines, Pumera et al [45] demonstrated that a significant shift of the half-wave potentials to lower values is provided to the MWCNT film (E 1/2 shift of 0.08 and 0.08 V for dopamine and catechol, respectively) and the SWCNT film (E 1/2 shift of 0.10 V for catechol) when compared with a bare gold electrode. Crevillén et al [16] used a wide range of complex molecules for evaluating the performance of detectors.…”

“…Higher loadings resulted in increased baseline noise and, therefore, subsequent work employed a CNT loading of 2 mg that offered the most favorable S/N characteristics [34]. Attempts were also made to study the influence of the underlying electrode on the performance of the detector [45]. CNT films cast on different substrate electrodes (glassy carbon (GC), Au, Pt) showed significantly different electrochemical behaviors.…”

Quantification of Quercetin Using Glassy Carbon Electrodes Modified with Multiwalled Carbon Nanotubes Dispersed in Polyethylenimine and Polyacrylic Acid

“…Different strategies have been proposed to disperse CNTs in order to make possible their application for the development of electrochemical sensors [5][6][7][8][9] and electrochemical detectors in CE [10][11][12]. Dispersion in surfactants [13,14], solvents [15] polymers [16][17][18][19][20][21][22][23], mineral oil [24][25][26][27], and ionic liquids [28] have been successfully performed.…”