Dual Electrocatalytic Behavior of Oxovanadium(IV) Salen Immobilized Carbon Materials Towards Cysteine Oxidation and Cystine Reduction: Graphene Versus Single Walled Carbon Nanotubes

Abstract

Oxovanadium(IV) salen (VO(salen)) (where salen=N,N’‐bis(salicylidene)ethylenediamine) is embedded onto reduced graphene oxide (rGO) and single walled carbon nanotubes (SWCNTs). The resulting materials, VO(salen) embedded rGO (rGO‐VO(salen)) and VO(salen) embedded SWCNTs (SWCNTs‐VO(salen)) show remarkable electrocatalytic activity for cysteine oxidation and cystine (the oxidized product of cysteine) reduction as demonstrated by cyclic voltammetry (CV). The materials, rGO‐VO(salen) and SWCNTs‐VO(salen) are characterized through spectroscopic and microscopic techniques. Transmission electron microscopy exhibits nanocrystalline view of VO(salen) on rGO‐VO(salen) while it appears like aggregated nodules in the SWCNTs‐VO(salen) revealing the nano‐structures excellently. Electrochemical cysteine oxidation is studied using rGO‐VO(salen) coated glassy carbon (GC) electrode (GC/rGO‐VO(salen)) and SWCNTs‐VO(salen) coated GC electrode (GC/SWCNTs‐VO(salen)). The efficiency of the catalytic platforms is compared. Overall number of electrons and electron transfer rate constant are obtained using rotating disc electrode for cysteine oxidation at GC/rGO‐VO(salen) and GC/SWCNTs‐VO(salen). Calibration curves for the determination of cysteine at GC/rGO‐VO(salen) and GC/SWCNTs‐VO(salen) exhibit linear range from 1.0 μM to 5.0 mM and 1.0 μM to 4.0 mM, respectively. GC/rGO‐VO(salen) and GC/SWCNTs‐VO(salen) are successfully applied for the real samples analysis with remarkable recovery.

Sensitive Determination of Acetaminophen in the Presence of Dopamine and Pyridoxine Facilitated by their Extent of Interaction with Single‐walled Carbon Nanotubes

“…In addition to these interactions, depending upon the functional groups of the analytes (phenolic, hydroxyl, amine and −NHCOCH 3 groups) they may have specific interactions to CNTs. Though numerous CNTs based composite materials are described to be beneficial in electrochemical sensing , it should be noted here that the influence of CNTs alone on the electrochemical sensing process is not studied in detail so far . Hence, in this study, a simple, sensitive and cost effective electrochemical route for the efficient quantification of AC, DA and PY based on single‐walled CNTs immobilized glassy carbon electrodes is reported.…”

“…The electrode modification requires only small amount of additional materials and the resulting electrodes can decrease the electrode fouling effects and detect the target analytes at low overpotentials . Recently, carbon based nanomaterials enticed the electrochemists extensively due to efficient promotion of electron transfer events on their surfaces . Carbon nanotubes (CNTs) are attractive nanomaterials which possess several interesting properties from the electroanalytical point of view, including high conductivity, durable mechanical stability and high surface area .…”

“…Recently, carbon based nanomaterials enticed the electrochemists extensively due to efficient promotion of electron transfer events on their surfaces . Carbon nanotubes (CNTs) are attractive nanomaterials which possess several interesting properties from the electroanalytical point of view, including high conductivity, durable mechanical stability and high surface area . These unique properties of CNTs are exploited in electrochemical science and technology to immobilize electrocatalysts and to increase the electrical communication within the immobilized molecules .…”

“…Carbon nanotubes (CNTs) are attractive nanomaterials which possess several interesting properties from the electroanalytical point of view, including high conductivity, durable mechanical stability and high surface area . These unique properties of CNTs are exploited in electrochemical science and technology to immobilize electrocatalysts and to increase the electrical communication within the immobilized molecules . For example, increased oxidation currents are reported for cysteine, glucose, DA, epinephrine, and ascorbic acid detection, thanks to presence of CNTs on electrodes .…”

“…These unique properties of CNTs are exploited in electrochemical science and technology to immobilize electrocatalysts and to increase the electrical communication within the immobilized molecules . For example, increased oxidation currents are reported for cysteine, glucose, DA, epinephrine, and ascorbic acid detection, thanks to presence of CNTs on electrodes . These huge improvements facilitated by the CNTs may be attributed to specific interactions of CNTs with the target analytes through π‐π interaction and/or Van der Waals forces, or the presence of edge‐plane‐like defect sites .…”