A novel co-reactant-free electrogenerated chemiluminescence (ECL) system is developed where Ru(bpy) emission is obtained on boron-doped diamond (BDD) electrodes. The method exploits the unique ability of BDD to operate at very high oxidation potential in aqueous solutions and to promote the conversion of inert SO into the reactive co-reactant SO. This novel procedure is rather straightforward, not requiring any particular electrode geometry, and since the co-reactant is only generated in situ, the interference with biological samples is minimized. The underlying mechanism is similar to that of the Ru(bpy)/SO system; however, the intensity of the emitted signal increases linearly with [SO] up to ∼0.6 M, with possible implications for analytical uses of the proposed procedure.

The electrogenerated chemiluminescence of luminol is a process by which light generation is triggered by adding hydrogen peroxide and then applying a suitable electrode potential. Here, we take this phenomenon one step forward by avoiding the addition of hydrogen peroxide using a smart combination of a boron-doped diamond electrode and a carbonate electrolyte to generate the hydrogen peroxide directly in situ. The reaction occurs because of the carbonate electrochemical oxidation to peroxydicarbonate and the following hydrolysis to hydrogen peroxide, which triggers the emission from luminol. The electrogenerated chemiluminescence emission has been optimized by an investigation of the applied potentials, the carbonate concentration, and the pH. Furthermore, these results have been used to shine a light on the reaction mechanisms. Because this method does not require the addition of hydrogen peroxide, it might find application in efforts to avoid instability of hydrogen peroxide or its interference with the analytes of interest.

An electrogenerated chemiluminescence (ECL) system by in situ coreactant production, where Ru(bpy) 3 2+ 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 3 2− ) into peroxydicarbonate (C 2 O 6 2− ), which further reacts with water to form hydrogen peroxide (H 2 O 2 ), which acts as a coreactant for Ru(bpy) 3 2+ ECL. Investigation of the mechanism reveals that ECL emission is triggered by the reduction of H 2 O 2 to hydroxyl radicals (OH • ), which later react with the reduced Ru(bpy) 3 + molecules to form excited states, followed by light emission. The ECL signal was found to increase with the concentration of CO 3 2− ; therefore, with the concentration of electrogenerated H 2 O 2 , although at the same time, higher concentrations of H 2 O 2 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.

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