Generation of anodic and cathodic currents based on photoexcited tris(2,2′-bipyrazine)ruthenium(II) in aqueous solutions

Abstract

Anodic and cathodic currents have been induced at an indium–tin oxide electrode by irradiation of aqueous solutions of tris(2,2′-bipyrazine)ruthenium(II)[Ru(bipyz)₃]²⁺ containing ethylene-diaminetetraacetic acid (H₄edta) and S₂O₈^2–, respectively. The anodic photocurrent is ascribed to reductive quenching of the photoexcited species [*Ru(bipyz)₃]²⁺ due to edta, as with C₂O₄^2–. On the other hand, the cathodic photocurrent is explained in terms of the oxidative quenching of [*Ru(bipyz)₃]²⁺ by S₂O₈^2–. A theoretical analysis is developed to account for the dependences of the photocurrents on applied potential, concentrations of [Ru(bipyz)₃]²⁺, edta and S₂O₈^2–, pH and light intensity.