Surface Enhanced Electrochemiluminescence of Ru(bpy)32+

Surface enhanced spectroscopy such as surface enhanced Raman spectrum (SERS) and surface enhanced fluorescence have been investigated extensively in the past two decades. Herein, we present experimental evidence to demonstrate the existence of a new surface enhanced spectroscopy, namely, surface enhanced electrochemiluminescence (SEECL). Our investigation indicates that the electrochemiluminescence (ECL) response of the Ru(bpy)(3)(2+)-tri-n-propylamine (TPrA) system could be significantly enhanced when the working electrode is modified with gold nanoparticle-SiO2 core-shell nanocomposites (AuNP@SiO2). It is worth noting that comparing with a working electrode modified with pure SiO2 nanoparticles, the electrochemical responses of the two electrodes were quite similar, but the ECL signal of the AuNP@SiO2 modified electrode was similar to 5 times higher than that of the SiO2 nanoparticles modified electrode. Thus we infer that the localized surface plasmon resonance (LSPR) of the AuNPs could be a major contribution to the ECL enhancement. Our investigations also demonstrate that the ECL enhancement is closely related to the thickness of the SiO2 layer. As much as 10 times ECL enhancement (comparing with the ECL intensity of bare electrode) is observed under the optimal conditions. The possible mechanism of the SEECL phenomenon is also discussed.