A novel boron-doped diamond (BDD)-coated platinum mesh electrode for spectroelectrochemistry

A boron-doped diamond (BDD)-coated platinum (Pt) mesh electrode has been fabricated for the first time and applied in thin-layer double-potential-step chronoabsorptometry of two high-potential redox species, Ru(bpy)33+/2+ and Fe(phen)33+/2+, in aqueous solutions. The BDD-coated mesh exhibited its characteristic as a diamond electrode by a low voltammetric background current and well-defined voltammetric responses. Moreover, in double-potential-step chronoabsorptometry with a thin-layer cell, the redox species reached a steady state rapidly and reversibly, to allow the determination of the E0′ value for Ru(bpy)33+/2+ in both alkaline (pH 8) and acidic (pH 5) solutions and for Fe(phen)33+/2+ in alkaline solutions. In contrast, on a bare Pt electrode, the Ru(bpy)33+/2+ and Fe(phen)33+/2+ redox waves are largely buried in that of water oxidation, and spectroelectrochemical responses are highly irreversible, due probably to the attack of O2 or OH radical on the redox species examined. The BDD-coated Pt mesh electrode will thus be an effective tool for measuring high-E0′ components in biosystems.