Grafting of diaminoalkane on glassy carbon surface and its functionalization

Diaminoalkanes (NH2(CH2)nNH2, n=7,10,12) were grafted onto a glassy carbon electrode (GCE) surface by amino cation radical formed during electrooxidation of amino group. The presence of diamine grafted layer at the GCE is demonstrated by Xray photoelectron spectroscopy. The effect of the grafted layer at the GCE surface on the redox responses of Ru(NH3)63+ and Fe(CN)63- redox probes has been investigated. Electrochemical impedance experiments indicate that the kinetics of electron transfer are slowed down when the scan rate taken to modify the GCE is low, and that diaminoalkane with longer alkyl-chain used has higher blocking characteristics. The amine-functionalized GCE is versatile not only to further covalently immobilize ferrocene acetic acid via carbodiimide coupling, but also as a charge-rich substrate to successfully adsorb heteropolyanion P2W18 in acidic solution by electrostatic interaction.