Highly sensitive electrogenerated chemiluminescence produced at Ru(bpy)32+ in Eastman-AQ55D-carbon nanotube composite film electrode

The electrochemistry and electrogenerated chemiluminescence (ECL) of tris(2,2′-bipyridyl)ruthenium(II) ion-exchanged in Eastman-AQ-carbon nanotube (CNT) composite films were investigated at a glassy carbon (GC) electrode. Eastman-AQ55D is a poly (ester sulfonic acid) cation exchanger available in a commercial dissolved form. It is much more hydrophilic than Nafion due to its unique structure, so Ru(bpy)32+ does not diffuse into the hydrophobic region where it may lose its electroactivity as that in Nafion. The interfused CNT could act as electronic wires that connect the electrode with Ru(bpy)32+, which made the composite film much more electronically conductive. Besides, the negatively charged CNT could also absorb some Ru(bpy)32+ which finally led to the increasing of Ru(bpy)32+. Moreover, the strong electrostatic interaction between AQ and Ru(bpy)32+ made the composite films much more stable. The combination of AQ and CNT brings excellent sensitivity with the detection limit as low as 3 × 10−11 M for TPA.