Electrocatalytic Oxidation of NADH Using Alizarin Immobilized Carbon Nanotube Modified Electrode

Abstract

Electrocatalytic oxidation of NADH has been demonstrated using an electrochemically immobilized Alizarin (AZ) on multiwalled carbon nanotube (MWCNT) modified glassy carbon electrode (GCE/AZ@MWCNT) in pH 7 phosphate buffer solution. The GCE/AZ@MWCNT shows three surface-confined redox peaks centered (E 1/2 ) at -0.067, -0.351 and -0.620 V vs Ag/AgCl, due to the 1,2 dihydroxy and anthraquinone (at two different energetic MWCNT) redox sites of the AZ. Calculated respective surface excess values are 59.13, 8.12 and 9.73×10 -10 mol.cm -2 . Amongst the three, the E 1/2 = -0.067 redox peak shows specific NADH electrocatalytic oxidation behavior in a concentration range = 0−7 mM by cyclic voltammetry. Transmission electron microscope characterization reveals immobilization of the AZ both on inner and outer walls of the MWCNT. Investigation on different CNTs viz., impure, purified, functionalized MWCNT, and single-walled carbon nanotube systems, the impure MWCNT shows the highest AZ immobilization and electrocatalytic behavior towards NADH oxidation.