Tris(2,2′-bipyridyl)ruthenium(II) electrogenerated chemiluminescence sensor based on carbon nantube dispersed in sol–gel-derived titania–Nafion composite films Original Research Article

A highly sensitive and stable tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)32+) electrogenerated chemiluminescence (ECL) sensor was developed based on carbon nanotube (CNT) dispersed in mesoporous composite films of sol–gel titania and perfluorosulfonated ionomer (Nafion). Single-wall (SWCNT) and multi-wall carbon nanotubes (MWCNT) can be easily dispersed in the titania–Nafion composite solution. The hydrophobic CNT in the titania–Nafion composite films coated on a glassy carbon electrode certainly increased the amount of Ru(bpy)32+ immobilized in the ECL sensor by adsorption of Ru(bpy)32+ onto CNT surface, the electrocatalytic activity towards the oxidation of hydrophobic analytes, and the electronic conductivity of the composite films. Therefore, the present ECL sensor based on the CNT–titania–Nafion showed improved ECL sensitivity for tripropylamine (TPA) compared to the ECL sensors based on both titania–Nafion composite films without CNT and pure Nafion films. The present Ru(bpy)32+ ECL sensor based on the MWCNT–titania––Nafion composite gave a linear response (R2 = 0.999) for TPA concentration from 50 nM to 1.0 mM with a remarkable detection limit (S/N = 3) of 10 nM while the ECL sensors based on titania–Nafion composite without MWCNT, pure Nafion films, and MWCNT–Nafion composite gave a detection limit of 0.1 μM, 1 μM, and 50 nM, respectively. The present ECL sensor showed outstanding long-term stability (no signal loss for 4 months).