Electrode Kinetics and Sensitivity of Nanostructured Electrodes from Different Carbon Fiber Precursor Materials

Abstract

Correlation of properties of common carbon fiber precursor materials, polyacrylonitrile (PAN) and pitch, with kinetics and sensitivity of microdisk electrodes, PAN T650, PAN HCB and Pitch P25, nanostructured by an electrochemical etching method was tested. Sensitivity of PAN electrodes is higher but kinetics are slower than at pitch electrodes due to more defects in PAN. Because of more surface oxides at PAN T650 adsorption of dopamine is greater than at PAN HCB electrodes but for uric acid adsorption is greater at PAN HCB. Uric acid sensitivity is related to high conductivity of PAN fibers, with an inverse relationship observed for dopamine.

High Sensitivity and Fast Oxidation of Caffeine in Coffee and Theophylline at Nanostructured Electrodes

“…The high sensitivity in FSV is unique and is not observed in CV (Table S1). In part, sensitivity enhancement in FSV is a result of signal averaging . In addition to signal averaging, adsorption, when present, can enhance sensitivity, especially at high scan rates .…”

“…In this work, catalyzed and fast electrochemical oxidation of CA and TP was realized at low positive potentials in aqueous solutions at nanostructured‐ nanoporous CFE in FSV. The apparent catalysis of the oxidation is a result of the electrode structure and rapid signal acquisition in FSV . As a result, in FSV with signal averaging, high sensitivity was achieved in the measurements of CA and TP in aqueous solutions that is significantly higher than in previously reported determinations.…”

Nanomolar detection of p-nitrophenol via in situ generation of p-aminophenol at nanostructured microelectrodes

“…32 These electrodes were then nanostructured as described previously by an electrochemical etch method to expose the nanofeatures at disk cross-sections of the fibers. 30 The electrochemical etch of the fiber surface exposes the nodules and nanopores that form the carbon fiber nanostructure. Potential window, scan rate, and electrolyte were selected to limit the overoxidation of the electrode surface and to allow reconditioning of the electrode surface for repeated use.…”

“…Nanostructured polyacrylonitrile (PAN) carbon fiber microdisk electrodes were used because of their demonstrated high sensitivity in electrochemical biosensing. 30 Since in practical applications, it is desirable to detect p-AP at micro-to submicromolar concentrations, the large active surface area of the nanostructured microdisk electrodes and rapid rate of mass transport to the microdisks were expected to contribute to the high detection sensitivity. 32 As pointed out above, the interest in the use of p-AP as a reporter molecule in the electrochemical detection of immunoassays stems from high sensitivity and reversibility of its electrode reactions.…”

“…Briefly, a carbon fiber connected to a copper wire was sealed in a micropipette tip and a cross section (microdisk) of the fiber was exposed by touch-polishing on a polishing wheel (Ecomet I, Buehler Ltd., Evanston, IL) using 600-grit SiC paper (Mark V Laboratory, East Granby, CT) and doubly distilled water as the lubricant. 30 Instrumentation A BAS-100 (Bioanalytical Systems Inc., West Lafayette, IN) electrochemical analyzer connected to a home-built amplifier was used for slow scan voltammetry (0.050 V s À1 ) measurements. The instrumental set-up for fast scan voltammetry (FSV) Scheme 1 Detection of p-nitrophenol (p-NP) by electrochemical reduction to p-aminophenol (p-AP) and subsequent measurement of the analytical signal due to p-AP.…”