Activation of a TiO2 Electrode Using Gold Particles for Efficient Electrogenerated Chemiluminescence from a Ruthenium Complex in Aqueous Solution

We report efficient electrogenerated chemiluminescence (ECL) generation from a ruthenium complex, Ru(bpy)(3)(2+), at TiO2 electrodes activated by gold nanoparticles made by electrodeposition and photoreduction methods. TiO2 electrodes made by anodizing a Ti microwire or using a solution-processing technique are used to generate ECL after being coated with gold. The improved stability and efficiency of ECL at gold particle-modified TiO2 are attributed to the large surface area of gold particles and efficient mass transfer of Ru(bpy)(3)(2+) and tripropylamine near the nanostructured gold surface. Stable ECL rings are produced at each of the individual gold particles and compared with their local photoluminescence profile. Future applications of the TiO2/gold substrate include single particle spectroelectrochemistry and ultrasensitive electrochemical ECL sensors.