Fabrication of a highly efficient solid state electrochemiluminescence sensor using Ru(bpy)₃²⁺ incorporated nanoZnO-MWCNTs-Nafion composite film

A highly sensitive and stable solid state electrochemiluminescence (ECL) sensor for tri-n-propylamine (TPrA, as coreactant) detection was developed using Ru(bpy)₃²⁺ ion-exchanged into the composite film of ZnO nanoparticles decorated multi-walled carbon nanotubes (nanoZnO-MWCNTs) and Nafion. The electrocatalytic activity of nano-ZnO active sites towards Ru(bpy)₃²⁺ redox reaction and also towards TPrA oxidation reaction significantly enhanced the electrochemical and ECL behaviors of Ru(bpy)₃²⁺/TPrA system. Under optimal experimental conditions, the logarithm of ECL signal intensity of the sensor was proportional to the logarithm of TPrA concentration in the range between 5 × 10^-11 M and 4 × 10^-4 M (r = 0.9996). The detection limit (S/N = 3) for TPrA was 1 × 10^-11 M. The relative standard deviation (RSD%) for repetitive measurements (n = 41) of 100 μM TPrA was about 4.2%. The proposed solid state ECL sensor also showed excellent reproducibility (8.1% for n = 5) and outstanding storage stability (83% of its initial ECL signal retained after 10 days).