Electrogenerated Chemiluminescence by in Situ Production of Coreactant Hydrogen Peroxide in Carbonate Aqueous Solution at a Boron-Doped Diamond Electrode.

An electrogenerated chemiluminescence (ECL) system by in situ coreactant production, where Ru(bpy) emission is generated at a boron-doped diamond (BDD) electrode, is presented. The system takes advantage of the unique properties of BDD to promote oxidation of carbonate (CO) into peroxydicarbonate (CO), which further reacts with water to form hydrogen peroxide (HO), which acts as a coreactant for Ru(bpy) ECL. Investigation of the mechanism reveals that ECL emission is triggered by the reduction of HO to hydroxyl radicals (OH), which later react with the reduced Ru(bpy) molecules to form excited states, followed by light emission. The ECL signal was found to increase with the concentration of CO; therefore, with the concentration of electrogenerated HO, although at the same time, higher concentrations of HO can quench the ECL emission, resulting in a decrease in intensity. The carbonate concentration, pH, and oxidation parameters, such as potential and time, were optimized to find the best emission conditions.