Electrocatalytic Oxidation of 4-Aminophenol Molecules at the Surface of an FeS 2 /Carbon Nanotube Modified Glassy Carbon Electrode in Aqueous Medium

Abstract

FeS 2 /carbon nanotube (CNT) nanocomposites were synthesized and immobilized on the surface of a glassy carbon electrode (GCE) in order to investigate the electrocatalytic conversion of 4-aminophenol (4-AP) into p-quinone in an aqueous medium. The reformed electronic properties (in terms of lowering of band-gap energy and charge-transfer resistance), as well as improved surface area, result in an enhanced redox reaction of 4-AP in the presence of FeS 2 -CNT NCs compared to that with FeS 2 alone. The 4-AP molecules undergo coupled two-proton and two-electron transfer quasi-reversible redox reactions with a symmetry factor of 0.55 and standard rate constant (k°) of 0.8 cm s −1 . Here, quinone imine is generated as an intermediate which is later converted into quinone in an irreversible hydrolysis reaction. The best catalytic performance can be obtained at the pH value of 7.0.