Gold Nanoparticle-Modified ITO Electrode for Electrogenerated Chemiluminescence: Well-Preserved Transparency and Highly Enhanced Activity

Abstract

Although it is desirable to use transparent indium tin oxide (ITO)-coated glass substrates as working electrodes for electrogenerated chemiluminescence (ECL), their applications in ECL studies of the Ru(bpy)₃²⁺ (bpy, 2,2‘-bipyridine)/tri-n-propylamine (TPrA) system have been limited because of the large overpotential of TPrA oxidation and the instability of the ITO surface at high anodic potentials. Here, we describe a simple method to achieve high ECL activity using ITO electrodes modified with gold nanoparticles (GNPs). The GNPs have been capped with fluorosurfactant ligands (i.e., Zonyl FSO). Much more facile TPrA oxidation was achieved by using the modified electrode, and an intense low-oxidation-potential (LOP) ECL signal was observed at ∼0.88 V versus SCE. The electrode transmittance drop upon modification was generally less than 5% over the visible spectrum when small-sized GNPs (∼4 nm) were employed. The well-preserved transparency and highly enhanced activity make the modified electrode promising for ECL studies.