Tris(2,2'-bipyridyl)ruthenium(ii) electrogenerated chemiluminescence sensor based on platinized carbon nanotube-zirconia-nafion composite films

Mesoporous films of platinized carbon nanotube-zirconia-Nafion composite have been used for the immobilization of tris(2,2'-bipyridyl)ruthenium (II) (Ru(bpy)₃^2{thorn}) on an electrode surface to yield a solid-state electrogenerated chemiluminescence (ECL) sensor. The composite films of Pt-CNT-zirconia-Nafion exhibit much larger pore diameter (3.55 nm) than that of Nafion (2.82 nm) and thus leading to much larger ECL response for tripropylamine (TPA) because of the fast diffusion of the analyte within the films. Due to the conducting and electrocatalytic features of CNTs and Pt nanoparticles, their incorporation into the zirconia - Nafion composite films resulted in the decreased electron transfer resistance within the films. The present ECL sensor based on the Pt - CNT- zirconia - Nafion gave a linear response (R² 1/4 0.999) for TPA concentration from 3.0 nM to 1.0 mM with a remarkable detection limit (S/N 1/4 3) of 1.0 nM, which is much lower compared to those obtained with the ECL sensors based on other types of sol-gel ceramic - Nafion composite films such as silica - Nafion and titania - Nafion.